MEMS microphone and method of manufacturing the same
10681472 ยท 2020-06-09
Assignee
Inventors
Cpc classification
B81B3/0051
PERFORMING OPERATIONS; TRANSPORTING
B81C2201/0132
PERFORMING OPERATIONS; TRANSPORTING
B81B2201/0257
PERFORMING OPERATIONS; TRANSPORTING
B81C2201/0109
PERFORMING OPERATIONS; TRANSPORTING
H04R31/00
ELECTRICITY
B81B2203/0127
PERFORMING OPERATIONS; TRANSPORTING
International classification
H04R31/00
ELECTRICITY
B81B3/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A MEMS microphone includes a substrate having a cavity, a back plate disposed over the substrate, the back plate having a plurality of acoustic holes, a diaphragm interposed between the substrate and the back plate, and being spaced apart from the substrate and the back plate, the diaphragm covering the cavity, forming an air gap between the back plate, and sensing an acoustic pressure to generate a displacement, and a plurality of anchors extending from an end portion of the diaphragm and along a circumference of the diaphragm, each of the anchors having a serpentine shape in a plan view and including a bottom portion making contact with an upper surface of the substrate to support the diaphragm from the substrate. Thus, the MEMS microphone may have adjustable area of the slit.
Claims
1. A MEMS microphone comprising: a substrate defining a cavity; a back plate disposed over the substrate, the back plate defining a plurality of acoustic holes; a diaphragm interposed between the substrate and the back plate, the diaphragm spaced apart from the substrate and the back plate, the diaphragm covering the cavity to form an air gap between the back plate and the diaphragm, and configured to sense an acoustic pressure to generate a displacement of the diaphragm; and a plurality of anchors extending from an end portion of the diaphragm, the plurality of anchors being arranged along a circumference of the diaphragm and spaced apart from one another along the circumference of the diaphragm, each of the anchors extending along the circumference of the diaphragm, presenting a serpentine shape in a plan view and including a bottom portion making contact with an upper surface of the substrate to support the diaphragm from the substrate.
2. The MEMS microphone of claim 1, wherein the anchors adjacent to each other define a slit to provide a passage through which acoustic pressure can pass.
3. The MEMS microphone of claim 2, wherein the slit has a length smaller than each of the plurality of anchors.
4. The MEMS microphone of claim 1, wherein the plurality of anchors are spaced apart from each other to surround the cavity.
5. The MEMS microphone of claim 1, wherein each of the plurality of anchors are integrally formed with the diaphragm.
6. The MEMS microphone of claim 1, wherein the diaphragm defines a plurality of vent holes penetrating therethrough, and the vent holes are disposed closer to a center of the diaphragm than the anchors are.
7. The MEMS microphone of claim 1, further comprising: an upper insulation layer disposed on the substrate, the upper insulation layer covering the back plate and holding the back plate to space the back plate from the diaphragm such that the air gap is maintained; and a chamber provided outside of the anchors, the chamber making contact with the lower surface of the substrate to support the upper insulation layer and to space the upper insulation layer from the diaphragm.
8. The MEMS microphone of claim 7, wherein the chamber is spaced apart from the diaphragm, the chamber defining a ring shape to surround the diaphragm.
9. The MEMS microphone of claim 7, wherein the chamber is integrally formed with the upper insulation layer.
10. A MEMS microphone comprising: a substrate being divided into a vibration area, a supporting area surrounding the vibration area, and the peripheral area surrounding the supporting area, the substrate defining a cavity formed in the vibration area; a diaphragm disposed over the substrate to cover the cavity, the diaphragm being spaced apart from the substrate and configured to generate a displacement in the cavity in response to an applied acoustic pressure; a back plate disposed over the diaphragm and in the vibration area, the back plate being spaced apart from the diaphragm to form an air gap between the diaphragm and the back plate; and a plurality of anchors disposed in the supporting area, the anchors extending from an end portion of the diaphragm toward the substrate, the plurality of anchors being arranged along a circumference of the diaphragm and spaced apart from one another along the circumference of the diaphragm to support the diaphragm from the substrate, each of the anchors extending along the circumference of the diaphragm presenting a serpentine shape in a plan view.
11. The MEMS microphone of claim 10, wherein the anchors adjacent to each other define at least slit to provide a passage through which the acoustic pressure moves.
12. The MEMS microphone of claim 11, wherein the slit is arranged one of a plurality of slits of the MEMS microphone, and a total area of the plurality of slits is proportional to the number of the plurality of slits.
13. The MEMS microphone of claim 11, wherein the slit has a length smaller than each of the anchors.
14. The MEMS microphone of claim 11, wherein each of the anchors has an area larger than that of the slit.
15. The MEMS microphone of claim 10, wherein the anchors are spaced apart from each other to surround the cavity.
16. The MEMS microphone of claim 10, further comprising: an upper insulation layer covering the back plate and holding the back plate to space the back plate from the diaphragm such that the air gap is maintained; and a chamber being disposed in the supporting area and extending from an end portion of the upper insulation layer toward the substrate to support the upper insulation layer, the chamber spacing the upper insulation layer from the diaphragm.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Example embodiments can be understood in more detail from the following description taken in conjunction with the accompanying drawings, in which:
(2) Example embodiments can be understood in more detail from the following description taken in conjunction with the accompanying drawings, in which:
(3)
(4)
(5)
(6)
(7)
(8)
(9)
DETAILED DESCRIPTION OF EMBODIMENTS
(10) Hereinafter, specific embodiments will be described in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein.
(11) As an explicit definition used in this application, when a layer, a film, a region or a plate is referred to as being on another one, it can be directly on the other one, or one or more intervening layers, films, regions or plates may also be present. By contrast, it will also be understood that when a layer, a film, a region or a plate is referred to as being directly on another one, it is directly on the other one, and one or more intervening layers, films, regions or plates do not exist. Also, although terms such as a first, a second, and a third are used to describe various components, compositions, regions, films, and layers in various embodiments of the present invention, such elements are not limited to these terms.
(12) Furthermore, and solely for convenience of description, elements may be referred to as above or below one another. It will be understood that such description refers to the orientation shown in the Figure being described, and that in various uses and alternative embodiments these elements could be rotated or transposed in alternative arrangements and configurations.
(13) In the following description, the technical terms are used only for explaining specific embodiments while not limiting the scope of the present invention. Unless otherwise defined herein, all the terms used herein, which include technical or scientific terms, may have the same meaning that is generally understood by those skilled in the art.
(14) The depicted embodiments are described with reference to schematic diagrams of some embodiments of the present invention. Accordingly, changes in the shapes of the diagrams, for example, changes in manufacturing techniques and/or allowable errors, are sufficiently expected. The Figures are not necessarily drawn to scale. Accordingly, embodiments of the present invention are not described as being limited to specific shapes of areas described with diagrams and include deviations in the shapes and also the areas described with drawings are entirely schematic and their shapes do not represent accurate shapes and also do not limit the scope of the present invention.
(15)
(16) Referring to
(17) As shown in
(18) In an example embodiment, the cavity 112 may have a cylindrical shape. Further, the cavity 112 may be formed in the vibration area VA to have a shape and a size corresponding to those of the vibration area VA.
(19) The diaphragm 120 may be disposed over the substrate 110. The diaphragm may generate a displacement which may occur due to the acoustic pressure. The diaphragm 120 may have a membrane structure. The diaphragm 120 may cover the cavity 112. The diaphragm 120 may have a lower surface to be exposed through the cavity 112. The diaphragm 120 is bendable in response to the applied acoustic pressure, and the diaphragm 120 is spaced apart from the substrate 110.
(20) As shown in
(21) In an example embodiment, the diaphragm 120 may have a shape of a circular disc, as shown in
(22) Referring to
(23) As shown in
(24) In an example embodiment of the present invention, the anchor 122 may be integrally formed with the diaphragm 120, as shown in
(25) Further, in an example embodiment, each of the anchors 122 may have an arc shape.
(26) Particularly, as shown in
(27) Also, as shown in
(28) Particularly, since each of the slits 124 is provided as the passage through which the acoustic pressure is discharged, an outlet area where the acoustic pressure move through the slits 124 may be adjusted by adjusting the total area of the slits 124. The outlet area may affect cut-off frequency characteristics of the MEMS microphone 100. Accordingly, the MEMS microphone 100 may reduce the outlet area of the acoustic pressure by adjusting the total area of the slits 124. As a result, the MEMS microphone 100 has improved frequency response characteristics.
(29) The back plate 130 may be disposed over the diaphragm 120. The back plate 130 may be disposed in the vibration area VA to face the diaphragm 120. For example, the back plate 130 may have a circular shape, as shown in
(30) In an example embodiment, the MEMS microphone 100 may further include an upper insulation layer 140 and a chamber 142 for supporting the back plate 130 from the substrate 110.
(31) In particular, the upper insulation layer 140 is positioned over the substrate 110 over which the back plate 130 is positioned. The upper insulation layer 140 may cover the back plate 130 to hold the back plate 130. Thus, the upper insulation layer 140 may space the back plate 130 from the diaphragm 120.
(32) As shown in
(33) A plurality of acoustic holes 132 may be formed through the back plate 130 such that the acoustic wave may flow through the acoustic holes 132. The acoustic holes 132 may be formed through the upper insulation layer 140 and the back plate 130 to communicate with the air gap AG.
(34) Further, the back plate 130 may include a plurality of dimple holes 134. Further, a plurality of dimples 144 may be positioned in the dimple holes 134. The dimple holes 134 may be formed through the back plate 130. The dimples 144 may be positioned to correspond to positions at which the dimple holes 134 are formed.
(35) The dimples 144 may prevent the diaphragm 120 from being coupled to a lower face of the back plate 130. That is, when the acoustic pressure reaches to the diaphragm 120, the diaphragm 120 can be bent in a semicircular shape toward the back plate 130, and then can return to its initial position. A bending degree of the diaphragm 120 may vary depending on a magnitude of the acoustic pressure and may be increased to such an extent that an upper surface of the diaphragm 120 makes contact with the lower surface of the back plate 130. When the diaphragm 120 is bent so much as to contact the back plate 130, the diaphragm 120 may attach to the back plate 130 and may not return to the initial position.
(36) According to example embodiments, the dimples 144 may protrude from the lower surface of the back plate 130 toward the diaphragm 120. Even when the diaphragm 164 is severely bent so much that the diaphragm 120 contacts the back plate 130, the dimples 144 may make the diaphragm 120 and the back plate 130 to be separated from each other so that the diaphragm 120 can return to the initial position.
(37) In the meantime, the chamber 142 may be positioned across a boundary between the peripheral area OA and the supporting area SA. The chamber 142 may support the upper insulation layer 140 to space the upper insulation layer 140 and the back plate 130 from the diaphragm 120. The chamber 142 may have a ring shape to surround the diaphragm 120, as shown in
(38) The chamber 142 may extend from the upper insulation layer 140 toward the substrate 110 to be coupled to the upper surface of the substrate 110, as shown in
(39) The chamber 142 may be spaced apart from the diaphragm 120 and positioned outside the anchor 130, as shown in
(40) In an example embodiment, the MEMS microphone 100 may further include a lower insulation layer pattern 150, a diaphragm pad 126, a sacrificial layer pattern 160, a back plate pad 136, a first pad electrode 172 and a second pad electrode 174.
(41) In particular, the lower insulation layer pattern 150 may be disposed on the upper surface of the substrate 110 and under the upper insulation layer 140.
(42) The diaphragm pad 126 may be formed on an upper surface of the lower insulation layer pattern 150. The diaphragm pad 126 may be located in the peripheral region OA. The diaphragm pad 126 may be electrically connected to the diaphragm 120 and may be doped with impurities. Though not shown in detail in figures, a connection portion may be doped with impurities to electrically connect the doped portion of the diaphragm 120 to the diaphragm pad 126.
(43) The sacrificial layer pattern 160 may be formed on the lower insulation layer pattern 150 on which the diaphragm pad 126 is formed, and may be positioned under the upper insulation layer 140. As shown in
(44) The back plate pad 136 may be formed on an upper face of the sacrificial layer pattern 160. The back plate pad 136 may be located in the peripheral region OA. The back plate pad 136 may be electrically connected to the back plate 130 and may be doped with impurities by in ion implantation process. Though not shown in detail in figures, a connection portion may be doped with impurities to connect the back plate 130 to the back plate pad 136.
(45) The first and second pad electrodes 172 and 174 may be disposed on the upper insulation layer 140 and in the peripheral area OA. The first pad electrode 172 is located on the diaphragm pad 126 to make contact with the diaphragm pad 126. On other hands, the second pad electrode 174 is located on the back plate pad 136 to make contact with the back plate pad 136. As shown in
(46) As described above, the MEMS microphone 100 according to example embodiments of the present invention includes anchors 122 extending along the circumference of the diaphragm 120 to adjust the area of the slits 124. Particularly, since the slits 124 serve as the passages for the acoustic pressure to move out, the MEMS microphone 100 may adjust the total area of the slits 124 such that the outlet area may be decreased. As a result, the pressure where the acoustic pressure flow out through the slits 124 may increase, compared to the prior one, such that the MEMS microphone 100 may have improved the cut-off frequency characteristics remarkably. As a result, the frequency response characteristic of the MEMS microphone 100 is improved and the performance of the MEMS microphone 100 can be improved.
(47) In addition, since each of the anchors 122 is provided in the serpentine structure, the flexibility of the diaphragm 120 can be remarkably improved while maintaining the rigidity of the diaphragm 120 as compared with the conventional one. As a result, the total harmonic distortion of the MEMS microphone 100 may be adjusted so as not to exceed an appropriate level, and the quality of the MEMS microphone may be improved. Further, since the anchors 122 may function to define the moving region of the etchant in the manufacturing process of the MEMS microphone 100, the process margin may be secured as compared with the conventional one, and the lower insulation layer pattern 150 may be prevented from remaining on the inner periphery of the anchors 122. As a result, the MEMS microphone 100 may prevent buckling phenomenon of the diaphragm 120 which might occur due to the residual insulation layer, and smooth movement of the acoustic waves may be achieved.
(48) Hereinafter, a method of manufacturing a MEMS microphone will be described in detail with reference to the drawings.
(49)
(50) Referring to
(51) Then, a diaphragm 120 and a plurality of anchors 122 are formed on the lower insulation layer 150 (step S120).
(52) The step S120 of forming the diaphragm 120 and the anchors 122 will be explained in detail.
(53) As shown in
(54) Referring to
(55) Impurities may be doped into both a portion of the first silicon layer 10 positioned in the vibration region VA and a portion of the first silicon layer 10 to be subsequently transformed into a diaphragm pad 126 through an ion implantation process.
(56) Next, the first silicon layer 10 is patterned to form a diaphragm 120, the anchors 122, and a diaphragm pad 126 is formed in the peripheral area OA. The anchor 122 may be formed in a serpentine shape to correspond to those of the anchor channels 152, respectively.
(57) Referring to
(58) Referring to
(59) The step S140 of forming the back plate 130 will be explained in detail.
(60) In particular, after a second polysilicon layer 20 is formed on an upper surface of the sacrificial layer 160, impurities are doped with the second silicon layer 20 by an ion implantation process. For example, the second silicon layer 20 may be formed using polysilicon.
(61) Next, as shown in
(62) Referring to
(63) The step S150 of forming the upper insulation layer 140 and the chamber 142 will be explained in detail.
(64) As shown in
(65) Next, an insulation layer 40 is formed on the sacrificial layer 160 having the chamber channel 30. Then, as shown in
(66) In an example embodiment, the insulation layer 40 may be formed using a material different from those of the lower insulation layer 150 and the sacrificial layer 160. For example, the insulation layer 40 is formed using silicon nitride or silicon oxynitride, whereas the lower insulation layer 150 and the sacrificial layer 160 are formed using silicon oxide.
(67) Referring to
(68) In particular, a thin film 50 is formed on the upper insulation layer 140 through which the first and the second contact holes CH1 and CH2 are formed, as shown in
(69) Next, the thin film 50 is patterned to form a first pad electrode 172 and a second pad electrode 174, as shown in
(70) Referring to
(71) Referring to
(72) Next, portions of the sacrificial layer 160 and the lower insulation layer 150, corresponding to the vibration area VA and the supporting area SA, are removed through an etching process using the cavity 112 and the acoustic holes 132 (Step S230). Thus, the diaphragm 120 is exposed through the cavity 112, and an air gap AG is formed. Further, portions of the lower insulation layer 150, which are located between the anchors 122, are removed to form a plurality of slits 124 (see
(73) Particularly, in step S230 of removing the sacrificial layer 160 and the lower insulating layer 150 from the vibration area VA and the supporting area SA, the anchors 122 and the chamber 142 may serve as a barrier for preventing the etchant to flow toward the peripheral area OA. Accordingly, an etching amount of the sacrificial layer 160 and the lower insulation layer 150 can be easily controlled, and the etchant may be prevented from remaining inside the anchors 12.
(74) In an example embodiment of the present invention, HF vapor may be used as the etchant for removing the sacrificial layer 160 and the lower insulating layer 150.
(75) As described above, according to some example embodiment of manufacturing the MEMS microphone the anchors 122 are formed to extend along the circumference of the diaphragm 120 without any additional process, and each of the anchors 122 may be formed into the serpentine structure. Accordingly, the MEMS microphone 100 may be manufactured to have improved frequency response characteristics and total harmonic distortion characteristics without increasing process time and manufacturing cost. In addition, since the process margin can be safely secured as compared with the prior one, it is possible to prevent the lower insulation layer 150 from remaining on the inner periphery of the anchors 122. As a result, the MEMS microphone 100 can prevent buckling phenomenon of the diaphragm 120 which might occur due to the residual insulation layer, and smooth movement of acoustic waves can be achieved.
(76) Although the MEM microphone has been described with reference to the specific embodiments, they are not limited thereto. Therefore, it will be readily understood by those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the appended claims.
(77) Various embodiments of systems, devices and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the invention. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, configurations and locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the invention.
(78) Persons of ordinary skill in the relevant arts will recognize that the invention may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the invention may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the invention can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. Moreover, elements described with respect to one embodiment can be implemented in other embodiments even when not described in such embodiments unless otherwise noted. Although a dependent claim may refer in the claims to a specific combination with one or more other claims, other embodiments can also include a combination of the dependent claim with the subject matter of each other dependent claim or a combination of one or more features with other dependent or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended. Furthermore, it is intended also to include features of a claim in any other independent claim even if this claim is not directly made dependent to the independent claim.
(79) Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.
(80) For purposes of interpreting the claims for the present invention, it is expressly intended that the provisions of Section 112(f) of 35 U.S.C. are not to be invoked unless the specific terms means for or step for are recited in a claim.