SUBSTRATE POLISHING HEAD, METHOD OF POLISHING SUBSTRATE AND MEMBRANE FOR SUBSTRATE POLISHING HEAD

Abstract

Provided is a substrate polishing head including a head part configured to be rotatable, a membrane mounted on the head part and configured to grip a substrate; a retainer ring surrounding the membrane, and a plurality of first electromagnets disposed within the head part and configured to form a magnetic field; wherein the membrane includes a first material having a hardening degree that changes depending on a magnetic field applied to the membrane.

Claims

1. A substrate polishing head comprising: a head part configured to be rotatable; a membrane connected to the head part on a first side of the membrane and configured to be connected to a substrate on a second side of the membrane opposite the first side of the membrane; a retainer ring surrounding the membrane; and a plurality of first electromagnets disposed within the head part and configured to form a first magnetic field; wherein the membrane includes a first material having a hardening degree that changes depending on a magnetic field applied to the membrane, wherein the magnetic field includes the first magnetic field.

2. The substrate polishing head of claim 1, further comprising a second electromagnet disposed within the retainer ring and configured to form a second magnetic field, wherein the magnetic field further includes the second magnetic field.

3. The substrate polishing head of claim 1, wherein the membrane includes a planar part facing the substrate and a plurality of partition walls intersecting the planar part.

4. The substrate polishing head of claim 3, wherein the planar part, the plurality of partition walls, and the head part define a plurality of spaces, and wherein a first particular electromagnet of the plurality of first electromagnets is disposed to overlap at least one space among the plurality of spaces based on a first direction intersecting the planar part.

5. The substrate polishing head of claim 3, wherein each partition wall of the plurality of partition walls is annulus-shaped, and the plurality of partition walls are disposed in a form of concentric circles.

6. The substrate polishing head of claim 3, wherein each partition wall of the plurality of partition walls has a bar shape extending between the planar part and the head part along a first direction intersecting the planar part.

7. The substrate polishing head of claim 3, wherein the planar part includes a first planar part connected to the plurality of partition walls and a second planar part disposed between the first planar part and the substrate.

8. The substrate polishing head of claim 7, wherein the plurality of partition walls and the first planar part include the first material, and wherein the second planar part does not include the first material.

9. The substrate polishing head of claim 7, wherein the first planar part and the second planar part both include the first material, and wherein a first content ratio of the first material within the first planar part and a second content ratio of the first material within the second planar part, are different from each other.

10. The substrate polishing head of claim 3, wherein at least one first electromagnet of the plurality of first electromagnets is disposed to overlap at least one partition wall of the plurality of partition walls, based on a first direction intersecting the planar part.

11. The substrate polishing head of claim 1, wherein a planar shape of each first electromagnet of the plurality of first electromagnets has a uniform size.

12. The substrate polishing head of claim 1, wherein a planar shape of each first electromagnet of the plurality of first electromagnets has a different size depending on a distance of the first electromagnet from a center of the head part.

13. The substrate polishing head of claim 1, wherein the first material includes Fe.sub.3O.sub.4.

14. A method of polishing a substrate, the method comprising: providing a substrate to a substrate polishing head, the substrate polishing head including a membrane including a first material having a hardening degree that changes depending on a magnetic field applied to the membrane, a head part connected to the membrane, and a plurality of first electromagnets disposed within the head part; providing gas to an internal space formed by the membrane and the head part; blocking power to a first set of first electromagnets of the plurality of first electromagnets overlapping the internal space along a first direction intersecting the substrate; and forming a first magnetic field by supplying power to a second set of first electromagnets of the plurality of first electromagnets overlapping the internal space along the first direction.

15. The method of claim 14, wherein the substrate polishing head further includes a retainer ring surrounding the membrane and a second electromagnet disposed within the retainer ring and configured to form a second magnetic field.

16. The method of claim 14, wherein a first polishing amount of a first region of the substrate overlapping in the first direction a first portion of the membrane corresponding to the first set of the first electromagnets of the plurality of first electromagnets to which power is blocked, is different from a second polishing amount of a second region of the substrate overlapping in the first direction a second portion of the membrane corresponding to the second set of the first electromagnets of the plurality of first electromagnets to which power is supplied.

17. The method of claim 16, wherein the first portion of the membrane is pressurized toward the substrate and the second portion is hardened.

18. The method of claim 17, wherein the membrane includes a planar part disposed to be parallel with the head part and a plurality of partition walls intersecting the planar part, and wherein the first portion of the membrane overlaps at least one partition wall of the plurality of partition walls in the first direction.

19. The method of claim 16, wherein an internal space formed by the first portion of the membrane and the head part is connected to an internal space formed by the second portion of the membrane and the head part.

20. A membrane for a substrate polishing head, the membrane comprising: a first planar part disposed to be parallel with a substrate; a plurality of partition walls extending from the first planar part along a first direction intersecting the substrate; and a second planar part disposed between the first planar part and the substrate, wherein at least one of the first planar part, the plurality of partition walls, or the second planar part includes a first material of which a hardening degree changes depending on a magnetic field, and wherein a first content ratio of the first material within the first planar part and a second content ratio of the first material within the second planar part are different from each other.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0014] These and/or other aspects, features, and advantages of the invention will become apparent and more readily appreciated from the following description of example embodiments, taken in conjunction with the accompanying drawings of which:

[0015] FIG. 1 is a schematic top plan view for illustrating process equipment including a substrate polishing device according to some example embodiments;

[0016] FIG. 2 is a schematic perspective view for illustrating a substrate polishing device according to some example embodiments;

[0017] FIG. 3 is an example diagram for illustrating a substrate polishing head of FIG. 2;

[0018] FIG. 4 is an example diagram showing a membrane for a substrate polishing head according to some example embodiments;

[0019] FIG. 5 is an example diagram showing a membrane for a substrate polishing head according to some example embodiments;

[0020] FIG. 6 is an example diagram schematically illustrating a substrate polishing head according to some example embodiments;

[0021] FIG. 7 is an example diagram schematically illustrating a substrate polishing head according to some other example embodiments;

[0022] FIG. 8 is an example diagram schematically illustrating a substrate polishing head according to still other example embodiments;

[0023] FIG. 9 is an example diagram schematically illustrating a substrate polishing head according to yet other example embodiments;

[0024] FIG. 10 is an example diagram schematically illustrating a substrate polishing head according to yet still other example embodiments;

[0025] FIG. 11 is an example diagram schematically illustrating a substrate polishing head according to yet further example embodiments;

[0026] FIGS. 12 and 13 are diagrams for illustrating operation of a substrate polishing head according to some example embodiments;

[0027] FIG. 14 is an example diagram showing a membrane for a substrate polishing head according to some other example embodiments; and

[0028] FIGS. 15 and 16 are example diagrams for illustrating a substrate polishing device according to still other example embodiments.

DETAILED DESCRIPTION

[0029] Before describing example embodiments in detail, the words and terminologies used in the specification and claims are not to be construed as limited to common or dictionary meanings but construed as meanings and conceptions coinciding with the technical spirit of the present disclosure under a principle that the inventor(s) may appropriately define the conception of the terminologies to explain the invention. Therefore, the example embodiments described in the specification and the configurations illustrated in the drawings are exemplary and do not fully cover the spirit of the present disclosure. Accordingly, it should be understood that there may be various equivalents and modifications to the embodiments described herein, within the scope of the present application. In the descriptions herein, a singular expression includes a plural expression unless context indicates otherwise. Thus, the description of a single item that is provided in plural should be understood to be applicable to the remaining plurality of items, unless context indicates otherwise.

[0030] It should be understood that terms such as comprise, include, including, and consist of are intended to indicate that a component has or is formed of only a feature, a number, a step, an operation, an element, a component, or a combination thereof, which are described in the specification, or the feature, number, step, operation, element, component, or group of elements may be combined with additional elements, etc. to form the component, unless the context indicates otherwise. The terms include and including are not intended to exclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items and may be abbreviated as /.

[0031] In addition, although terms such as first, second, etc. may be used to describe various elements, these elements are not limited by the terms herein, and the terms may be used to distinguish one element from another. Within the scope of the present disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0032] In addition, expressions such as upper surface, upper portion, lower surface, lower portion, and side portion, hereinafter are represented based on a direction illustrated in a figure and may be represented otherwise when the direction of a corresponding object changes. Spatially relative terms, such as below, lower, above, upper, side and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as below or beneath other elements or features would then be oriented above the other elements or features. Thus, for example, the term below can encompass both an orientation of above and below. The shape or size of elements in drawings may be exaggerated for clearer description.

[0033] It will be appreciated that planarization, and planar, etc., as used herein refer to elements (e.g., surfaces) that need not be perfectly geometrically planar, but may include acceptable variances that may result from standard manufacturing processes. Additionally, the terms parallel and perpendicular, as used herein encompass identicality or near identicality of parallel and perpendicular, including variations that may occur resulting from conventional manufacturing processes.

[0034] The term substrate may denote a base substrate (e.g., an initial semiconductor substrate forming the base of the wafer in the final wafer product, such as a bulk semiconductor substrate (e.g., formed of crystalline silicon), a silicon on insulator (SOI) substrate, etc.), or a stack structure including such a base substrate and layers formed on the substrate.

[0035] It will be understood that when an element is referred to as being connected to or on another element, it can be directly connected or coupled to or on the other element or intervening elements may be present. In contrast, when an element is referred to as contacting or in contact with another element (or using any form of the word contact), there are no intervening elements present at the point of contact.

[0036] As used herein, the words surround, surrounding and surrounded are intended to mean that an element is outside the other element. The elements may be touching or not. The surrounding element may or may not completely surround an inner element.

[0037] As used herein, the terms overlap and overlapping are intended to mean that an element overlaps another element partially or fully in at least one direction. The elements may be touching or not. There may be intervening elements therebetween.

[0038] Hereinafter, example embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0039] FIG. 1 is a schematic top plan view for illustrating process equipment including a substrate polishing device according to some example embodiments.

[0040] Referring to FIG. 1, the process equipment according to some example embodiments may include a substrate polishing device 1, an index part 2, a transport robot 3, and a cleaning device 4.

[0041] According to some example embodiments, the substrate polishing device 1 may perform a polishing process on a substrate W. The substrate polishing device 1 may include a polishing pad 110 disposed on a lower base 100, a platen 120, a slurry supply part 130, a substrate polishing head 200, and a pad conditioner 160.

[0042] According to some example embodiments, the index part 2 may provide a space where a cassette CS holding the substrate W is placed. The index part 2 may transfer the substrate W out of the cassette CS to the transport robot 3 or transfer the substrate W on which the polishing process is completed into the cassette CS.

[0043] According to some example embodiments, the transport robot 3 may be provided between the substrate polishing device 1 and the index part 2. The transport robot 3 may transport the substrate W between the substrate polishing device 1 and the index part 2. For example, a load cup 105 adjacent to the transport robot 3 may be disposed in the substrate polishing device 1. The load cup 105 may provide a space where the substrate W waits temporarily. In addition, an exchanger 107 may be provided between the transport robot 3 and the load cup 105. The exchanger 107 may transport the substrate W transported from the index part 2 by the transport robot 3 to the load cup 105 or may transport the substrate W disposed on the load cup 105 to the transport robot 3.

[0044] According to some example embodiments, the cleaning device 4 may be provided between the index part 2 and the transport robot 3. The substrate W polished in the substrate polishing device 1 may be disposed on the load cup 105. The substrate W disposed on the load cup 105 may be transported to the cleaning device 4 by the transport robot 3 disposed to be adjacent to the load cup 105. The cleaning device 4 may clean a remaining contaminant on the polished substrate W. The cleaned substrate W may be transported back to the index part 2 and held in the cassette CS. Accordingly, the polishing process on the substrate W may be completed.

[0045] FIG. 2 is a schematic perspective view for illustrating a substrate polishing device according to some example embodiments.

[0046] Referring to FIG. 2, the substrate polishing device according to some example embodiments may include the polishing pad 110, the platen 120, the slurry supply part 130, the substrate polishing head 200, and the pad conditioner 160.

[0047] According to some example embodiments, the polishing pad 110 may be disposed on the platen 120. The polishing pad 110 may be provided as, but is not limited to, a plate form with a predetermined thickness, for example, a circular plate form. The polishing pad 110 may include a polishing surface 110S facing the substrate W. The polishing surface 110S may have predetermined roughness. For example, the polishing surface 110S may have a bump. While the polishing process is performed, the polishing surface 110S may be in contact with the substrate W and polish the substrate W.

[0048] According to some example embodiments, the polishing pad 110 may include a plurality of grooves. The grooves may be formed on the polishing surface 110S of the polishing pad 110. For example, each of the grooves may be introduced and formed from the polishing surface 110S. While the polishing process is performed, the grooves may be provided as a path of slurry S for polishing and may facilitate the flow of the slurry S for polishing.

[0049] According to some example embodiments, the platen 120 may support the polishing pad 110. For example, the polishing pad 110 may be disposed on an upper surface of the platen 120. In addition, the platen 120 may be rotatable. The rotatable platen 120 may rotate the polishing pad 110 disposed on the platen 120. For example, a first drive shaft 122 connected to a lower portion of the platen 120 may receive rotational power transmitted from a first motor 124 and may rotate. The platen 120 may rotate the polishing pad 110 around a rotation axis perpendicular to the upper surface of the platen 120.

[0050] According to some example embodiments, the slurry supply part 130 may be disposed to be adjacent to the polishing pad 110. While the polishing process is performed, the slurry supply part 130 may supply the slurry S for polishing on the polishing surface 110S of the polishing pad 110. The slurry S for polishing may be supplied smoothly between the substrate W and the polishing pad 110 through the grooves formed on the polishing surface 110S.

[0051] In some example embodiments, the slurry S for polishing may include a plurality of polishing particles. For example, the slurry S for polishing may include a reactant with dispersed polishing particles and/or a chemical reaction catalyst. The polishing particles may function as an abrasive. The polishing particles may include, for example, metal oxide, metal oxide coated with organic or inorganic materials, or colloidal metal oxide. For example, the polishing particles may include but are not limited to at least one of silica, alumina, ceria, titania, zirconia, magnesia, germania, mangania, or a combination thereof.

[0052] According to some example embodiments, the substrate polishing head 200 may be disposed to be adjacent to the polishing pad 110. The substrate polishing head 200 may provide the substrate W on the polishing surface 110S of the polishing pad 110. For example, the substrate polishing head 200 may operate to maintain the substrate W on the polishing pad 110.

[0053] In some example embodiments, the substrate polishing head 200 may independently control polishing parameters (for example, pressure) related to the substrate W. For example, the substrate polishing head 200 may include a retainer ring 240 for maintaining the substrate W under a flexible membrane. The substrate polishing head 200 may be defined by the flexible membrane and include a plurality of pressurizable chambers independently controllable. The pressurizable chambers may apply independently controllable pressure to related zones on the flexible membrane or related zones on the substrate W.

[0054] According to some example embodiments, the substrate polishing head 200 may be rotatable. The rotatable substrate polishing head 200 may rotate the substrate W fixed to the substrate polishing head 200. For example, a second drive shaft 152 connected to an upper portion of the substrate polishing head 200 may receive rotational power transmitted from a second motor 154 and may rotate.

[0055] According to some example embodiments, the substrate polishing head 200 may be supported by a support 156. For example, the support 156 may be but is not limited to a carousel or a track. In some example embodiments, the substrate polishing head 200 may translate laterally across an upper surface of the polishing pad 110. For example, the substrate polishing head 200 may vibrate on a slider of the support 156 or by rotational vibration in the support 156.

[0056] In FIG. 2, it is illustrated but merely an example that one substrate polishing head 200 is provided on the polishing pad 110. For another example, to use a surface area of the polishing pad 110 efficiently, a plurality of substrate polishing heads 200 may also be provided on the polishing pad 110. Further, in FIG. 2, it is illustrated but merely an example that a rotational direction of the platen 120 and a rotational direction of the substrate polishing head 200 are identical to each other. The two may also rotate in different rotational directions.

[0057] According to some example embodiments, the pad conditioner 160 may be disposed to be adjacent to the polishing pad 110. The pad conditioner 160 may perform a conditioning process for the polishing surface 110S of the polishing pad 110. Through this, the pad conditioner 160 may maintain the polishing surface 110S of the polishing pad 110 stably so that the substrate W is polished effectively during the polishing process.

[0058] FIG. 3 is an example diagram for illustrating a substrate polishing head of FIG. 2. FIG. 4 is an example diagram showing a membrane for a substrate polishing head according to some example embodiments. FIG. 5 is an example diagram showing a membrane for a substrate polishing head according to some example embodiments.

[0059] Referring to FIGS. 3 to 5, the substrate polishing head 200 may include a head part 201, the retainer ring 240, a membrane 250, a first electromagnet 310, and a second electromagnet 320.

[0060] According to some example embodiments, the head part 201 may be disposed on the membrane 250. The head part 201 may include a housing 210, a base assembly 220, and a clamp 230.

[0061] According to some example embodiments, the housing 210 may be connected to the second drive shaft 152 of FIG. 2 and may be lifted and lowered vertically. The base assembly 220 may be connected to a lower portion of the housing 210 and support the housing 210.

[0062] According to some example embodiments, the housing 210 may be a shape corresponding to a shape of the substrate W to be polished. For example, the substrate W may be a disk shape, and the shape of the housing 210 may be a cylindrical shape corresponding to the shape of the substrate W. However, example embodiments are not limited thereto. The housing 210 may be connected to the second motor 154 of FIG. 2 through the second drive shaft 152 of FIG. 2 and rotated by the second motor 154 of FIG. 2. The housing 210 may be lifted and lowered vertically and bring the substrate W into contact with the polishing pad 110 of FIG. 2.

[0063] According to some example embodiments, the base assembly 220 may be connected to the lower portion of the housing 210 and support the housing 210, and as the housing 210 is lifted and lowered vertically, the base assembly 220 may also be lifted and lowered vertically. The base assembly 220 may also be a cylindrical shape to correspond to the shape of the substrate W, but example embodiments are not limited thereto.

[0064] According to some example embodiments, the clamp 230 may connect the membrane 250 to the base assembly 220. FIG. 3 illustrates that the clamp 230 is disposed throughout the membrane 250 and the retainer ring 240, but example embodiments are not limited thereto. For example, the clamp 230 may cover the membrane 250 alone and not cover the retainer ring 240. In this case, the retainer ring 240 may be connected to a lower portion of the base assembly 220.

[0065] According to some example embodiments, the retainer ring 240 may be connected to the lower portion of the base assembly 220 and disposed to surround the membrane 250 and the substrate W, which may be adhered to the membrane 250. The retainer ring 240 may be an annular shape to surround the substrate W, but example embodiments are not limited thereto. The retainer ring 240 may prevent the substrate W adhering to the membrane 250 from detaching even though the substrate polishing head 200 moves during the polishing process.

[0066] According to some example embodiments, the membrane 250 may be accommodated in the base assembly 220 and connected to the clamp 230. The membrane 250 may be surrounded by the retainer ring 240. The membrane 250 may adhere the substrate W and pressurize the substrate W onto the polishing pad 110 of FIG. 2. The membrane 250 may be mounted on the head part 201 and may grip the substrate W. The membrane 250 may have a shape corresponding to the shape of the substrate W. For example, when the substrate W is disk-shaped, the membrane 250 may also be disk-shaped and may be configured to grip, adhere or pressurize the substrate, but example embodiments are not limited thereto.

[0067] According to some example embodiments, the membrane 250 may include a flexible material. For example, the membrane 250 may include silicon (Si), Ethylene Propylene Diene Monomer (EPDM), and/or polyurethane rubber, but it is not limited to these materials. The membrane 250 may be flexibly expanded or contracted by compressed gas provided to an internal space SP.

[0068] According to some example embodiments, the membrane 250 may include a material (hereinafter referred to as a first material) of which a hardening degree changes depending on a magnetic field applied to the membrane. The membrane 250 may include ferrimagnetic materials as a first material. For example, the membrane 250 may include at least one selected from the group consisting of magnetite such as Fe.sub.3O.sub.4, maghemite such as Fe.sub.2O.sub.3, and ferrites such as MFe.sub.3O.sub.4, NiFe.sub.2O.sub.4, or CoFeO.sub.4 but it is not limited to these materials. The magnetic field may include a first magnetic field (e.g., a first magnetic field component) formed by a first electromagnet 310 and/or a second magnetic field (e.g., a second magnetic field component) formed by a second electromagnet 320. For example, the membrane 250 may include Fe.sub.3O.sub.4 as the first material. The membrane 250 may be partially hardened based on a magnetic field formed by the first electromagnet 310 and the second electromagnet 320. In example embodiments, the two combined magnetic fields (e.g., the first magnetic field or first magnetic field component and the second magnetic field or second magnetic field component) may form a signal combined magnetic field. For example, the magnetic field may include two components.

[0069] According to some example embodiments, the membrane 250 may include a plurality of partition walls 251 and a planar part 255. The plurality of partition walls 251 and the planar part 255 may be connected to the head part 201 and form an internal space SP, where compressed gas may be provided.

[0070] According to some example embodiments, the planar part 255 may be formed to correspond to the shape of the substrate W. For example, the planar part 255 may be disk-shaped to adhere or pressurize the substrate W, but example embodiments are not limited thereto. A lower surface of the planar part 255 may provide a mounting surface to which the substrate W adheres. For example, the planar part 255 may be composed of a vacuum chuck for adhering the substrate W.

[0071] According to some example embodiments, the planar part 255 may include a first planar part 252 and a second planar part 253. The planar part 255 may face the substrate W. The first planar part 252 and the second planar part 253 may be disposed to be parallel with the substrate W. The first planar part 252 may be connected to the plurality of partition walls 251. The first planar part 252 may be disposed on the second planar part 253. The second planar part 253 may be disposed below the first planar part 252. The second planar part 253 may be disposed between the first planar part 252 and the substrate W.

[0072] According to some example embodiments, the plurality of partition walls 251 may intersect the planar part 255. The plurality of partition walls 251 may be formed as a ring shape protruding from the planar part 255 in a first direction D1. The first direction D1 may be a direction intersecting the substrate W or the planar part 255. The plurality of partition walls 251 may extend from the planar part 255 along the first direction D1.

[0073] According to some example embodiments, each partition wall of the plurality of partition walls 251 may be disposed to surround a partial region of the planar part 255. Each partition wall of the plurality of partition walls 251 may be annulus-shaped and the plurality of partition walls may be disposed in the form of concentric circles. Each partition wall of the plurality of partition walls 251 may include a portion extending horizontally. For example, each partition wall of the plurality of partition walls 251 may include a portion extending in a direction toward a center of the planar part 255 and an opposite direction, but example embodiments are not limited thereto.

[0074] According to some example embodiments, the plurality of partition walls 251 and the first planar part 252 may include the first material. For example, a partial region of the plurality of partition walls 251 and the first planar part 252 influenced by a magnetic field formed by the first electromagnet 310 or the second electromagnet 320 may be hardened. When the first electromagnet 310 or the second electromagnet 320 forms no magnetic field, the plurality of partition walls 251 and the first planar part 252 may not be hardened. According to non-limiting examples, the second planar part 253 may not include the first material. The second planar part 253 may have a constant hardening degree irrespective of a magnetic field formed by the first electromagnet 310 or the second electromagnet 320.

[0075] According to some example embodiments, a gas flow path 235 may be in communication with the internal space SP formed between the membrane 250 and the head part 201. FIG. 3 illustrates that the gas flow path 235 penetrates the clamp 230 alone, which is merely an example though, and example embodiments are not limited thereto. The gas flow path 235 may be formed to penetrate the housing 210 and the base assembly 220. The gas flow path 235 may be formed to be plural in number. The compressed gas may enter or exit through the gas flow path 235. The compressed gas may be provided to the internal space SP between the membrane 250 and the clamp 230 and the base assembly 220 through the gas flow path 235. By the compressed gas, the membrane 250 may adhere the substrate W and pressurize the substrate W onto the polishing pad 110 of FIG. 2.

[0076] According to some example embodiments, the first electromagnet 310 may be disposed within the head part 201. For example, the first electromagnet 310 may be disposed within the base assembly 220. However, example embodiments are not limited thereto. The first electromagnet 310 may also be disposed within other elements of the head part 201 on the membrane 250. The first electromagnet 310 may form a magnetic field (or first magnetic field) according to power supplied from outside. There may be a plurality of first electromagnets 310 on the membrane 250. The first electromagnet 310 may form the magnetic field for the membrane 250, or the plurality of first electromagnets 310 may combine to form the magnetic field for the membrane 250.

[0077] According to some example embodiments, the first electromagnet 310 may overlap the membrane 250 in the first direction D1. One internal space SP may overlap the plurality of first electromagnets 310. At least one first electromagnet of the plurality of first electromagnets 310 may overlap at least one partition wall of the plurality of partition walls 251 of the membrane 250 in the first direction D1.

[0078] According to some example embodiments, the second electromagnet 320 may be disposed within the retainer ring 240. However, example embodiments are not limited thereto. The second electromagnet 320 may also be disposed as a separate element between the membrane 250 and the retainer ring 240. The second electromagnet 320 may form a magnetic field (or second magnetic field) according to power supplied from outside. There may be a plurality of second electromagnets 320 at a side portion of the membrane 250. The second electromagnet 320 may form the magnetic field for the membrane 250, or the plurality of second electromagnets 320 may combine to form the magnetic field for the membrane 250.

[0079] FIG. 6 is an example diagram schematically illustrating a substrate polishing head according to some example embodiments.

[0080] Referring to FIG. 6, the plurality of first electromagnets 310 and the plurality of second electromagnets 320 may be connected to a power supply part 330. The power supply part 330 may control power supplied to each first electromagnet of the plurality of first electromagnets 310 and the plurality of second electromagnets 320. For example, the power supply part 330 may supply power to some first electromagnets 310 (first set of the first electromagnets) among the plurality of first electromagnets 310 and block power to the remaining first electromagnets 310 (second set of the first electromagnets). For another example, the power supply part 330 may block power to the plurality of first electromagnets 310 and supply power to each second electromagnet of the plurality of second electromagnets 320.

[0081] The power supply may include one or more of a variety of power supplies known to those skilled in the art.

[0082] According to some example embodiments, the plurality of first electromagnets 310 may be disposed to face the membrane 250 in the first direction D1. More specifically, the plurality of first electromagnets 310 may be disposed to face the planar part 255 of the membrane 250.

[0083] According to some example embodiments, the plurality of partition walls 251 and the first planar part 252 may include the first material. In the plurality of partition walls 251 and the first planar part 252, a partial region influenced by a magnetic field formed by the first electromagnet 310 or the second electromagnet 320 may be hardened. Accordingly, even though gas is provided to the internal space SP, the hardened partial region of the plurality of partition walls 251 and the first planar part 252 may not be altered toward the second planar part 253. The plurality of partition walls 251 and the first planar part 252 may be formed as an integral element. However, example embodiments are not limited thereto. The plurality of partition walls 251 and the first planar part 252 may be formed as separate elements.

[0084] According to some example embodiments, the second planar part 253 may not include the first material. For example, even though the first electromagnet 310 and/or the second electromagnet 320 forms a magnetic field, the second planar part 253 may not be hardened. Therefore, based on an altered degree of the plurality of partition walls 251 and the first planar part 252, the second planar part 253 may also be altered toward the substrate W of FIG. 3 disposed thereunder.

[0085] According to some example embodiments, the membrane 250 may form the internal space SP with the head part 201 of FIG. 3 and the plurality of partition walls 251. The internal space SP may be disposed to be plural in number. According to example embodiments, a planar part 255 (or first planar part 252), plurality of partition walls 251 and the head part 201 define one or more internal spaces SP. One internal space SP among the plurality of internal spaces SP may overlap the plurality of first electromagnets 310 in the first direction D1. A first particular electromagnet of the plurality of first electromagnets 310 may be disposed to overlap at least one space among the plurality of internal spaces SP in the first direction D1 intersecting the planar part.

[0086] According to some example embodiments, at least one first electromagnet 310 among the plurality of first electromagnets 310 may overlap at least some partition walls of the plurality of partition walls 251 in the first direction D1. At least some of the plurality of partition walls 251 may be hardened by a magnetic field formed by the first electromagnet 310 overlapped in the first direction D1. At least some of the plurality of partition walls 251 may not be hardened when the first electromagnet 310 overlapped in the first direction D1 forms no magnetic field and accordingly may be altered by gas provided to the internal space SP. For example, when pressurized by the gas provided to the internal space SP, the plurality of partition walls 251 may be altered to be bent or concave in a second direction D2. The second direction D2 may be a direction intersecting the first direction D1 and being parallel with the planar part 255.

[0087] In example embodiments, the membrane 250 includes a planar part 255 facing the substrate and a plurality of partition walls 251 intersecting the planar part 255. The first portion of the membrane 250 may overlap at least one partition wall of the plurality of partition walls 251 in the first direction D1.

[0088] FIG. 7 is an example diagram schematically illustrating a substrate polishing head according to some other example embodiments. To describe the substrate polishing head according to some other example embodiments, differences from the description with reference to FIG. 6 are mainly described.

[0089] Referring to FIG. 7, the plurality of partition walls 251 and the first planar part 252 may not include the first material. The plurality of partition walls 251 and the first planar part 252 may not change in hardening degrees depending on a magnetic field formed by the first electromagnet 310 or the second electromagnet 320. For example, the plurality of partition walls 251 and the first planar part 252 may not be hardened even though a magnetic field is formed by the first electromagnet 310 or the second electromagnet 320. Accordingly, even though a magnetic field is formed by the first electromagnet 310 and/or the second electromagnet 320, the plurality of partition walls 251 and the first planar part 252 may be altered toward the second planar part 253 and pressurize the second planar part 253 when gas is provided to the internal space SP.

[0090] According to some example embodiments, the second planar part 253 may include the first material. The second planar part 253 may have a change in a hardening degree depending on a magnetic field formed by the first electromagnet 310 or the second electromagnet 320. For example, the second planar part 253 may be hardened by a magnetic field formed by the first electromagnet 310 or the second electromagnet 320. Accordingly, when a magnetic field is formed by the first electromagnet 310 or the second electromagnet 320, the second planar part 253 may not be altered toward the substrate W of FIG. 3 disposed thereunder even though gas is provided to the internal space SP and the plurality of partition walls 251 and the first planar part 252 pressurize the second planar part 253.

[0091] FIG. 8 is an example diagram schematically illustrating a substrate polishing head according to still other example embodiments. To describe the substrate polishing head according to still other example embodiments, differences from the description with reference to FIG. 6 are mainly described.

[0092] Referring to FIG. 8, the membrane 250 may include the plurality of partition walls 251 and the planar part 255. The planar part 255 may be a single-layer. For example, the planar part 255 may not include the first planar part 252 of FIG. 6 and the second planar part 253 of FIG. 6 and include one planar part 255 alone.

[0093] According to some example embodiments, the planar part 255 may be in contact with the substrate W of FIG. 3 disposed below the membrane 250. A partial region of the planar part 255 influenced by a magnetic field formed by some of the first electromagnets 310 or the second electromagnets 320 may be hardened. Another partial region of the planar part 255 not influenced by a magnetic field formed by some of the first electromagnets 310 or the second electromagnets 320 may not be hardened. Therefore, when gas is provided to the internal space SP, the partial region of the planar part 255 that is not hardened may be altered toward the substrate W of FIG. 3 and pressurize the substrate W of FIG. 3, and the hardened partial region of the planar part 255 may not pressurize the substrate W of FIG. 3.

[0094] FIG. 9 is an example diagram schematically illustrating a substrate polishing head according to yet other example embodiments. To describe the substrate polishing head according to yet other example embodiments, differences from the description with reference to FIG. 6 are mainly described.

[0095] Referring to FIG. 9, the plurality of partition walls 251, the first planar part 252, and the second planar part 253 may include the first material. The plurality of partition walls 251 and the first planar part 252 may include the first material with an identical content ratio. Therefore, for magnetic fields of identical intensity, the plurality of partition walls 251 and the first planar part 252 may have a change in hardening degrees by identical magnitudes.

[0096] According to some example embodiments, the second planar part 253 may include the first material with a different content ratio from the plurality of partition walls 251 and the first planar part 252. Therefore, for magnetic fields of identical intensity, the second planar part 253 may have a change in hardening degrees by a magnitude different from the plurality of partition walls 251 and the first planar part 252. For example, when a content ratio of the first material within the second planar part 253 is less than a content ratio of the first material within the plurality of partition walls 251 and the first planar part 252, the second planar part 253 may be hardened less than the plurality of partition walls 251 and the first planar part 252 by a magnetic field formed by the first electromagnet 310 or the second electromagnet 320.

[0097] FIG. 10 is an example diagram schematically illustrating a substrate polishing head according to yet still other example embodiments. To describe the substrate polishing head according to yet still other example embodiments, differences from the description with reference to FIG. 6 are mainly described.

[0098] Referring to FIG. 10, the plurality of partition walls 251 and the second planar part 253 may include the first material, and the first planar part 252 may not include the first material. The plurality of partition walls 251 and the second planar part 253 may change in hardening degrees depending on a magnetic field formed by the first electromagnet 310 and/or the second electromagnet 320. The first planar part 252 may not change in a hardening degree depending on a magnetic field formed by the first electromagnet 310 and/or the second electromagnet 320.

[0099] According to some example embodiments, when a magnetic field is formed by the first electromagnet 310 and/or the second electromagnet 320 and gas is provided to one internal space SP formed by the plurality of partition walls 251, the first planar part 252, the second planar part 253, and the plurality of partition walls 251 may be hardened and not be altered even though gas is provided to the internal space SP. Even though a magnetic field is formed, the first planar part 252 not including the first material may not be hardened and thus may be altered toward the second planar part 253 by the gas provided to the internal space SP, but an altered degree of the first planar part 252 may relatively decrease as the plurality of partition walls 251 connected to the first planar part 252 are hardened. The second planar part 253 including the first material may be hardened when a magnetic field is formed by the first electromagnet 310 and/or the second electromagnet 320. Therefore, a pressurizing degree of the second planar part 253 altered toward the substrate W of FIG. 3 may be less than a degree of the first planar part 252 being altered and pressurizing the second planar part 253.

[0100] FIG. 11 is an example diagram schematically illustrating a substrate polishing head according to yet further example embodiments. To describe the substrate polishing head according to yet further example embodiments, differences from the description with reference to FIG. 9 are mainly described.

[0101] Referring to FIG. 11, the plurality of partition walls 251, the first planar part 252, and the second planar part 253 may include the first material. The first material included in each partition wall of the plurality of partition walls 251, the first planar part 252, and the second planar part 253 may have different content ratios from each other. Therefore, for magnetic fields of identical intensity, the plurality of partition walls 251, the first planar part 252, and the second planar part 253 may have different hardening degrees. For example, when influenced by a magnetic field formed by the first electromagnet 310 and/or the second electromagnet 320, the plurality of partition walls 251 may have a hardening degree greater than the hardening degrees of the first planar part 252 and the second planar part 253. In addition, the second planar part 253 may have a hardening degree less than the hardening degrees of the plurality of partition walls 251 and the first planar part 252. For magnetic fields of identical intensity, the first planar part 252 may have a hardening degree greater than the hardening degree of the second planar part 253 and less than the hardening degree of the plurality of partition walls 251.

[0102] According to some example embodiments, each of the plurality of partition walls 251 and the first planar part 252 may be a separate element. Therefore, the content ratio of the first material included in the plurality of partition walls 251 and the content ratio of the first material included in the first planar part 252 may be different from each other.

[0103] According to some example embodiments, the first planar part 252 and the second planar part 253 may both include the first material, and a first content ratio of the first material within the first planar part and a second content ratio of the first material within the second planar part, are different from each other.

[0104] FIGS. 12 and 13 are diagrams for illustrating operation of a substrate polishing head according to some example embodiments. To describe the operation of the substrate polishing head according to some example embodiments, differences from the description with reference to FIG. 6 are mainly described.

[0105] Referring to FIG. 12, the power supply part 330 may supply power to some first electromagnets of the plurality of first electromagnets 310 (i.e., a second set of first electromagnets) and block power to the remainder of the first electromagnets of the plurality of first electromagnets 310 (i.e., a first set of first electromagnets). For example, power may be blocked to an inactive first electromagnet 310a among the plurality of first electromagnets 310, and power may be supplied to an active first electromagnet 310b among the plurality of first electromagnets 310. The inactive first electromagnet 310a may not form a magnetic field because power is not supplied. The active first electromagnet 310b may form a magnetic field because power is supplied.

[0106] According to some example embodiments, power may be supplied to some of the plurality of first electromagnets 310 overlapping one internal space SP in the first direction D1 from the power supply part 330, and power may be blocked to the remainder. The plurality of first electromagnets 310 overlapping one internal space SP in the first direction D1 may include both the inactive first electromagnet 310a and the active first electromagnet 310b. For example, the plurality of first electromagnets 310 disposed on one internal space SP disposed at a central portion of the membrane 250 may include both the inactive first electromagnet 310a and the active first electromagnet 310b. Similarly, the plurality of first electromagnets 310 disposed on another internal space SP disposed adjacent to one internal space SP disposed at the central portion of the membrane 250 may include both the inactive first electromagnet 310a and the active first electromagnet 310b.

[0107] According to some example embodiments, a magnitude of pressurizing the substrate W may be controlled by changing a hardening degree of the membrane 250 using the inactive first electromagnet 310a and the active first electromagnet 310b even within one internal space SP divided by the plurality of partition walls 251. Generally, because a magnitude of pressurizing a substrate by a membrane may be controlled by controlling the pressure of gas supplied inside one internal space divided by a plurality of partition walls, there is a limitation in controlling a pressurizing magnitude partially for a membrane forming one internal space. In contrast, because the present disclosure may partially adjust the hardening degree of the membrane 250 using the inactive first electromagnet 310a and the active first electromagnet 310b for the membrane 250 forming one internal space SP and partially control the magnitude of pressurizing the substrate W by the membrane 250, a polishing profile may be finely controlled.

[0108] According to some example embodiments, the power supply part 330 may supply power to the second electromagnet 320. The second electromagnet 320 may receive power and form a magnetic field. The plurality of partition walls 251 or the first planar part 252 influenced by the magnetic field formed by the second electromagnet 320 may be hardened. For example, a portion of the plurality of partition walls 251 or the first planar part 252 in an edge portion disposed adjacent to the retainer ring 240 where the second electromagnet 320 is disposed, may be influenced by the magnetic field formed by the second electromagnet 320 (second magnetic field) and hardened. FIG. 12 illustrates that power is supplied to all of the plurality of second electromagnets 320, but example embodiments are not limited thereto. For example, power may be supplied to some of the plurality of second electromagnets 320, and power may be blocked to the remainder. The plurality of partition walls 251 overlapping some of the plurality of second electromagnets 320 to which power is supplied in the second direction D2 may be hardened, and the plurality of partition walls 251 overlapping the remainder of the plurality of second electromagnets 320 to which power is blocked in the second direction D2 may not be hardened.

[0109] According to some example embodiments, a first portion 251a of the plurality of partition walls 251 and a first portion 252a of the first planar part 252 may be a portion not influenced by a magnetic field formed by the active first electromagnet 310b and a magnetic field formed by the second electromagnet 320. The first portions 251a and 252a may be a portion of the plurality of partition walls 251 and the first planar part 252 corresponding to the inactive first electromagnet 310a. For example, the first portions 251a and 252a of the plurality of partition walls 251 and the first planar part 252 may be a portion not overlapping the active first electromagnet 310b in the first direction D1 and overlapping the inactive first electromagnet 310a in the first direction.

[0110] According to some example embodiments, the first portions 251a and 252a and a region where the inactive first electromagnet 310a is disposed may not completely overlap each other in the first direction. For example, even though the first portions 251a and 252a and the region where the inactive first electromagnet 310a is disposed may not completely overlap each other in the first direction as the area of the first portions 251a and 252a is less than the area of the region where the inactive first electromagnet 310a is disposed, a portion of the plurality of partition walls 251 and the first planar part 252 not influenced by the magnetic field formed by the active first electromagnet 310b and the magnetic field formed by the second electromagnet 320 may be the first portions 251a and 252a.

[0111] According to some example embodiments, the first portions 251a and 252a may not be influenced by the magnetic field formed by the active first electromagnet 310b and the magnetic field formed by the second electromagnet 320 and thus not hardened. Therefore, when gas is provided to the internal space SP, the first portions 251a and 252a may be altered toward the second planar part 253. FIG. 12 illustrates that the first portion 252a of the first planar part 252 is altered toward the second planar part 253 and the first portion 251a of the plurality of partition walls 251 is not bent laterally or not altered, but example embodiments are not limited thereto. The first portion 251a of the plurality of partition walls 251 may be pressurized by gas provided to the internal space SP and may also be bent laterally or altered.

[0112] According to some example embodiments, a second portion 251b of the plurality of partition walls 251 and a second portion 252b of the first planar part 252 may be a portion influenced by a magnetic field formed by the active first electromagnet 310b or a magnetic field formed by the second electromagnet 320. The second portions 251b and 252b may be a portion of the plurality of partition walls 251 and the first planar part 252 corresponding to the active first electromagnet 310b. For example, the second portions 251b and 252b of the plurality of partition walls 251 and the first planar part 252 may be a portion overlapping the active first electromagnet 310b in the first direction D1 and not overlapping the inactive first electromagnet 310a in the first direction.

[0113] According to some example embodiments, the second portions 251b and 252b and a region where the active first electromagnet 310b is disposed may not completely overlap each other in the first direction. For example, even though the second portions 251b and 252b and the region where the active first electromagnet 310b is disposed may not completely overlap each other in the first direction as the area of the second portions 251b and 252b is greater than the area of the region where the active first electromagnet 310b is disposed, a portion of the plurality of partition walls 251 and the first planar part 252 influenced by the magnetic field formed by the active first electromagnet 310b or the magnetic field formed by the second electromagnet 320 may be the second portions 251b and 252b.

[0114] According to some example embodiments, the second portions 251b and 252b may be influenced by the magnetic field formed by the active first electromagnet 310b or the magnetic field formed by the second electromagnet 320 and thus be hardened. Therefore, even though gas is provided to the internal space SP, the second portions 251b and 252b may not be altered toward the second planar part 253.

[0115] According to some example embodiments, the second planar part 253 disposed between the first planar part 252 and the substrate W may be altered along an altered profile of the first planar part 252. The second planar part 253 may not include the first material of which a hardening degree changes depending on a magnetic field and thus may be altered toward the substrate W along the altered profile of the first planar part 252. For example, a portion of the second planar part 253 overlapping the first portions 251a and 252a in the first direction D1 may be altered toward the substrate W. A portion of the second planar part 253 overlapping the second portions 251b and 252b in the first direction D1 may not be altered toward the substrate W.

[0116] According to some example embodiments, a first region R1 of the substrate W overlapping the first portions 251a and 252a in the first direction D1 may be altered along an altered shape of the first portions 251a and 252a. The first region R1 of the substrate W may be pressurized toward the polishing pad 110 of FIG. 2 by the altered first portions 251a and 252a. A second region R2 of the substrate W overlapping the second portions 251b and 252b in the first direction D1 may be pressurized toward the polishing pad 110 of FIG. 2 relatively less than the first region R1 by the hardened second portions 251b and 252b.

[0117] According to some example embodiments, because degrees by which the first region R1 and the second region R2 of the substrate W are pressurized by the membrane 250 are different, polishing amounts may differ. For example, the first polishing amount of the first region R1 pressurized relatively more than the second region R2 may be greater than the second polishing amount of the second region R2.

[0118] Referring to FIG. 13, power may be blocked to the second electromagnet 320. The second electromagnet 320 may not form a magnetic field because power is not supplied. A portion of the plurality of partition walls 251 or the first planar part 252 in the edge portion disposed adjacent to the retainer ring 240 where the second electromagnet 320 is disposed may not be influenced by the magnetic field and thus not be hardened. FIG. 13 illustrates that power is blocked to all of the plurality of second electromagnets 320, but example embodiments are not limited thereto. For example, power may be supplied to some of the plurality of second electromagnets 320, and power may be blocked to the remainder.

[0119] According to some example embodiments, the first portions 251a and 252a of the plurality of partition walls 251 and the first planar part 252 may also be formed in a portion adjacent to the retainer ring 240. Because the second electromagnet 320 disposed within the retainer ring 240 forms no magnetic field, the first portions 251a and 252a may be formed in the edge portion adjacent to the retainer ring 240. Therefore, because the first portions 251a and 252a are altered toward the second planar part 253 when gas is provided to the internal space SP, the first region R1 of the substrate W may be pressurized in the edge portion toward the polishing pad 110 of FIG. 2.

[0120] As described with reference to FIGS. 12 and 13, by adjusting the hardening degree of the membrane 250 using magnetic fields formed by the first electromagnet 310 and the second electromagnet 320, a degree by which the substrate W is pressurized toward the polishing pad 110 of FIG. 2 may be adjusted. Even though the internal space SP where gas is provided is separated by the plurality of partition walls 251 of the membrane 250, a pressurizing degree of the membrane 250 for the substrate W may be controlled even within one internal space SP using the first electromagnet 310 and the second electromagnet 320. The plurality of first electromagnets 310 may apply a magnetic field to at least a portion of the planar part 255 partitioned by the plurality of partition walls 251. Accordingly, by controlling a polishing profile of the substrate W, polishing uniformity may be improved.

[0121] According to some example embodiments, the internal space SP formed by the first portions 251a and 252a and the head part 201 of FIG. 3 may be connected to the internal space SP formed by the second portions 251b and 252b and the head part 201 of FIG. 3. For example, one internal space SP disposed at the central portion of the membrane 250 may include a partial space formed by the first portions 251a and 252a and the head part 201 of FIG. 3 and a partial space formed by the second portions 251b and 252b and the head part 201 of FIG. 3. For another example, one internal space SP disposed at the central portion of the membrane 250 may be formed by the first portions 251a and 252a and the head part 201 of FIG. 3, and another internal space SP disposed adjacent to the central portion may be formed by the second portions 251b and 252b and the head part 201 of FIG. 3. In an example, a partition wall of the plurality of partition walls 251 between two internal spaces SP may be formed as a bar shape so that the two internal spaces SP are not separated and in communication with each other.

[0122] FIG. 14 is an example diagram showing a membrane for a substrate polishing head according to some other example embodiments. To describe the membrane for the substrate polishing head according to some other example embodiments, differences from the description with reference to FIG. 5 are mainly described.

[0123] Referring to FIG. 14, the membrane for the substrate polishing head according to some example embodiments may include the plurality of partition walls 251 with a bar shape. each partition wall of the plurality of partition walls 251 may extend in the first direction D1 of FIG. 3 between the planar part 255 of the membrane 250 and the head part 201 of FIG. 3. The plurality of partition walls 251 may be disposed to be distributed throughout the planar part 255 of FIG. 4 of the membrane 250. For example, distances between the plurality of partition walls 251 may be uniform. For another example, distances between the plurality of partition walls 251 may not be uniform. The distances between the plurality of partition walls 251 may decrease as being closer to a center of the planar part 255, and the distances between the plurality of partition walls 251 may increase as being farther from the center.

[0124] FIGS. 15 and 16 are example diagrams for illustrating a substrate polishing device according to still other example embodiments.

[0125] Referring to FIG. 15, planar shapes of the plurality of first electromagnets 310 may have a uniform size. The plurality of first electromagnets 310 with an identical size in a planar shape to each other may be disposed throughout the entire area of the membrane 250 with a uniform distance.

[0126] Referring to FIG. 16, planar shapes of the plurality of first electromagnets 310 may not have a uniform size. The plurality of first electromagnets 310 may change in size across the entire area of the membrane 250. The plurality of first electromagnets 310 may include a first sub-electromagnet 311 and a second sub-electromagnet 312. The size of a planar shape of the first sub-electromagnet 311 may be smaller than the size of a planar shape of the second sub-electromagnet 312. In this case, each of the first sub-electromagnet 311 and the second sub-electromagnet 312 may have an identical number of times of a coil winded.

[0127] For example, the first sub-electromagnet 311 may be disposed to overlap the central portion and the edge portion of the membrane 250. The second sub-electromagnet 312 may be disposed between the first sub-electromagnet 311 disposed at the central portion of the membrane 250 and the first sub-electromagnet 311 disposed at the edge portion of the membrane 250. By adjusting the size of the first electromagnet 310, a region of a magnetic field applied to the membrane 250 may be controlled, and a polishing profile may be controlled more finely.

[0128] Unlike what is shown in FIG. 16, the plurality of first electromagnets 310 with identical sizes may be disposed in an annular shape. For example, the plurality of first electromagnets 310 with a first size may be disposed on the membrane 250 in an annular shape with a first diameter, and the plurality of first electromagnets 310 with a second size different from the first size may be disposed on the membrane 250 in an annular shape with a second diameter different from the first diameter. The planar shape of each first electromagnet of the plurality of first electromagnets 310 may have different sizes depending on a distance from the center of the membrane 250.

[0129] While various example embodiments of the present disclosure are described in detail herein, the scope of the present invention is not limited thereto, and it will be apparent to those of ordinary skill in the art that modifications and variations may be made without departing from the scope of the present disclosure as defined by the appended claims. In addition, the aforementioned example embodiments may be implemented with some elements removed, and each example embodiment may be implemented in combination with each other.