PHYSICAL VAPOR DEPOSITION APPARATUS

Abstract

A physical vapor deposition (PVD) apparatus includes: a vacuum chamber; a pedestal arranged in the vacuum chamber and configured to support a substrate; a target arranged on the vacuum chamber and including a deposition material; a shield arranged on an inner sidewall of the vacuum chamber toprotect the vacuum chamber from the deposition material; a target power supply applying a target voltage to the target to generate plasma in the vacuum chamber; and a magnet configured to induce the plasma to the target; and a magnetic field formation line connected with the target power supply, wherein the magnetic field formation line surrounds the shield symmetrically with respect to a center of the shield to form a magnetic field in the vacuum chamber.

Claims

1. A physical vapor deposition (PVD) apparatus comprising: a vacuum chamber; a pedestal arranged in the vacuum chamber and configured to support a substrate; a target amanged corm the vacuum chamber and including a deposition material; a shield arranged on an inner sidewall of the vacuum chamber to protect the vacu t. n chamber from the deposition material; a target power supply applying a target voltage to the target to generate plasma in the vacuum chamber; and a magnet configured to induce the plasma to the target; and a magnetic field formation line connected with the target power supply, wherein the magnetic field formation line surrounds the shield symmetrically with respect to a center of the shield to form a magnetic field in the vacuum chamber,

2. The PVD apparatus of claim 1, wherein the magnetic field formatioi line has an annular shape configured to surround the shield.

3. The PVD apparatus of claim 2, wherein the magnetic field formationline is positioned under the target.

4. The PVD apparatus of claim 2, wherein the magnetic field formation line has a radius of about √{square root over (2)}±√{square root over (2)}×20% times a radius of the shield.

5. The PVD apparatus of claim 1, wherein the magnetic field formation line comprises a cable.

6. The PVD apparatus of claim 1, wherein the magnetic field formation line comprises a conductive ring configured to surround the shield.

7. The PVD apparatus of claim 6, wherein the conductive ring makes contact with an outer sidewall of the vacuum chamber.

8. The PVD apparatus of claim 6, wherein the conductive ring is spaced apart from an outer sidewall of the vacuum chamber.

9. The PVD apparatus of claim 1, wherein the magnetic field formation litre comprises a first connection point and a second connection point wherein the first connection point is connected to the target power supply, wherein the second connection point is connected to a ground line, and wherein the first and second connect on points are symmetrical with each other with respect to the center of the shield.

10. The P VD apparatus of claim further comprising a shield power supply configured to apply a shield voltage to the shield.

11. The PVD apparatus of claim 10, wherein the shield power supply is connected to a portion of the magnetic field formation lite that is symmetrical with a first connection point of the magnetic field fonnation line with respect to the center of the shield, wherein the first connection point is connected to the target power .supply.

12. The PVD apparatus of claim 1, further comprising a collimator arranged between the target and the pedestal.

13. A physical vapor deposition (PVD) apparatus comprising: a vacuum chamber; a pedestal arranged in the vacuum chamber and configured to support a substrate; a target arranged on the vacuum chamber and including a deposition material; a shield arranged on an inner sidewall of the vacuum chamber to protect the vacuum chamber from the deposition r material; a target power supply applying a target voltage to the target to generate plasma in the vacuum chamber; and a magnet configured to induce the plasma to the target; a magnetic field formation line having a first connection point connected with the target power supply, wherein the magnetic field formation line has an annular shape configured to surround the shield symmetrically with respect to a center of the shield to form a magnetic field in the vacuum chamber; and a ground line connected to a second connection point of the magnetic field formation line, wherein the second connection point is symmetrical with the first connection point with respect to the center of the shield.

14. The PVD apparatus of claim 13, wherein the magnetic field formation line has a radius of about √{square root over (2)}±√{square root over (2)}×20% times a radius of the

15. The PVD apparatus of claim 13, further comprising a shield power supply configured to apply a shield voltage to the shield.

16. The PVD apparatus of claim 15, wherein the shield power supply is connected to a portion of the magnetic field formation line that is symmetrical with the first connection point of the gnetic field formation lino with respect to the center of the shield.

17. The PVD apparatus of claim 13, further comprising a collimator arranged between the target and the pedestal.

18. A physical vapor deposition (PVD) apparatus comprising: a vacuum chamber; a pedestal arranged m the vacuum chamber and c nfigured to support a substrate; a target arranged on a first surface of the vacuum chamber and including, a deposition material; a shield arranged on an inner sidewall of the vacuum chamber to protect the vacuum chamber from the deposition material; a tarqet power supply applying a target voltage to the target to generate plasma in tlae vacuum chamber; and a magnet configured to induce the plasma to the target; a power line connected to the target power supply and a first portion of the vacuum chamber; and a ground line connected, to a second portion of the vacuum chamber, wherein the second portion is symmetrical with the first portion with respect to a center of the shield.

19. The PVD apparatus of claim 18, further comprising a shield power supply configured to apply a shield voltage to the shield.

20. The PVD apparatus of claim 19, wherein the shield power supply is connected to the second portion of the vacuum chamber that is symmetrical with the first portion of the vacuum chamber, which is connected to the target power supply, with respect to a center of the shield.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other features of the present inventive concept will become more apparent by describing in detail example embodiments thereof, with reference to the accompanying, drawings, in which:

[0010] FIG. 1 is a cross-sectional view illustrating a physical vapor deposition (PVD) apparatus in accordance with an example embodiment of the present inventive concept;

[0011] FIG. 2 is a cross-sectional view taken along a. line A-A′ in FIG. 1 in accordance with an example embodiment of the present inventive concept;

[0012] FIG. 3 is a cross-sectional view illustrating a conventional PVD apparatus in accordance with a comparative example;

[0013] FIG. 4 is a graph showing magnetic field components formed in the conventional PVD apparatus in FIG. 3 in accordance with a comparative example;

[0014] FIG. 5 is a graph showing magnetic field components formed by a magnetic -field formation line of the PVD apparatus in FIG. 1 in accordance with an example embodiment of the present inventive concept;

[0015] FIG. 6 is a graph showing magnetic field components formed in the PVD apparatus in FIG. 1 by the magnetic field components in FIG. 5;

[0016] FIG. 7 is an image showing a magnetic field formed by the conventional PVD apparatus in FIG. 3 in accordance with a comparative example;

[0017] FIG. 8 is an imago showing a magnetic field formed by a. magnetic field formation line of the PVD apparatus in FIG. 1 in accordance with an example embodiment of the present inventive concept;

[0018] FIG. 9 is an image showing a distribution of plasma in the conventional PVD apparatus in FIG. 3;

[0019] FIG. 10 is an image showing a distribution of plasma in the IND apparatus in FIG. 1 accordance with an example embodiment of the present inventive concept;

[0020] FIG. 11 is an image showing a thickness distribution of a layer on a substrate using the conventional PVD apparatus in FIG. 3 in accordance with a comparative example;

[0021] FIG. 12 is an image showing a thickness distribution of a layer on a substrate using the PVD apparatus in FIG. 1 in accordance with an example embodiment of the present inventive concept;

[0022] FIG. 13 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept;

[0023] FIG. 14 is a cross-sectional view taken along a line B-B′ in FIG. 13 in accordance with an example embodiment of the present inventive concem

[0024] FIG. 15 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept;

[0025] FIG. 16 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept;

[0026] FIG. 17 is a cross-sectional view taken along a line C-C′ in FIG: 16 in accordance with an example embodiment of the present inventive concept;

[0027] FIG. 18 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept; and

[0028] FIG. 19 is a cross-sectional view illustrating a PVD apparatus in accordance with example embodiment of the present inventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Hereinafter, example embodiments of the present inventive concept will be described in detail with reference to the accompanying drawings.

[0030] FIG. 1 is a cross-sectional view illustrating a physical vapor deposition (PVD) apparatus in accordance with an example embodiment of the present inventive concept, and FIG. 2 is a cross-sectional view taken along a line A-A′ FIG. 1.

[0031] Referring to FIGS. 1 and 2, a PVD apparatus 100 according to an example embodiment of the present inventive concept may include a vacuum chamber 110, a shield 120, a pedestal 130, a target 140, a magnet 150, a target power supply 160, a shield power supply 170 and a magnetic field formation line 184.

[0032] The vacuum chamber 110 may have an inner space configured to receive a substrate. The substrate rhaay include, for example, a semiconductor substrate, but the present inventive concept is not limited thereto. The inner space of the vacuum chamber 110 may receive vacuum from a vacuum pump. Plasma may be formed in the inner space of the vacuum chamber 110. The vacuum chamber 110 may include a conductive material or a non-conductive material. if the vacuum chamber 110 inchides the conductive material, the vacuum chamber 110 may include a metal, but the present inventive concept is not limited thereto, Further, the vacuum chamber 110 may have a cylindrical shape, but the present inventive concept is not limited thereto

[0033] The shield 120 may be arranged on an inner sidewall of the vacuum chamber 110. The shield 120 may protect the vacuum chamber 110 from a deposition material formed on the semiconductor substrate. For example, the shield 120 may include a conductive material such as a metal. The shield 120 may have an annular shape, but the present inventive concept is not limited thereto.

[0034] The pedestal 130 may be arranged in a lower region of the inner space of the vacuum chamber 110. The semiconductor substrate may be placed on an upper surface of the pedestal 130.

[0035] The target 140 may be arranged on an upper surface of the vacuum chamber 110. The target 140 may include the deposition material. For example, the deposition material may he for deposited on a substrate. An upper end of the shield 120 may be positioned adjacent to an edge portion of the target 140. For example, the shield 120 may be spaced apart from the target 140.

[0036] The magnet 150 may be arranged on the target 140. The magnet 150 may induce the plasma in the inner space of the vacuum chatnber 110 to the target 140 to concentrate the plasma under the target 140. For example, the magnet 150 may include a permanent magnet. The nla gnet 150 nay have a fixed structure. In addition, the magnet 150 may have a rotary structure. In this case, the magnet 150 may be rotated with respect to a center of the target 140. Thus, the plasm may also be rotated with respect to the center of the target 140 by the rotation of the magnet 150.

[0037] The target power supply 160 mays electrically connected to the target 140. The target power supply 160 may apply a target power to the target 140 to generate the plasma in the inner space of the vacuum chamber 110. For example, the target power supply 160 may apply a direct current (DC) voltage of about −600V to the target 140.

[0038] For example, the target power supply 160 may he connected with the target 140 through a first power line 180. A second power line 182 extended from the target power supply 160 may be positioned adjacent to an outer sidewall of the shield 120. For example, the second power line 182 may be connected to an outer sidewall of the vacuum chamber 110. The first power line 180 and the second power line 182 may include cables.

[0039] In an example embodiment of the present inventive concept, the target power supply 160 may be connected to the magnet 150 through the first power line 180.

[0040] The shield power supply 170 may be electrically connected with the shield 120 to apply a shield voltage to the shield 120. The shield power supply 170 may be connected with the shield 120 through a first shield line 190. For example, the first shield line 190 may be connected to the upper end of the shield 120. For example, the shield power supply 170 may apply a DC voltage of about +100V to the shield 120. Additionally, an RF filter 172 may be arranged between the shield power supply 170 and the shield 120. The first shield line 190 may include a cable.

[0041] The magnetic field formation line 184 may be configured to surround an outer sidewail of the vacuum chamber 110. For example, the magnetic field formation line 184 may be configured to surround the outer sidewall. of the shield 120. Thus, the magnetic field formation line 184 may be symmetrical with respect to the center of the shield 1,0 In an example embodiment of the present inventive concept, the nab netic field formation line 184 may include a cable.

[0042] In an example embodiment of the present inventive concept, because the shield 120 may have the annular shape, the magnetic field formation line 184 may also have an annular shape, but the present inventive concept is not limited thereto For example, the shield 120 may have a square frame shape, and thus, the magnetic field formation line 184 may also have a square frame shape. For example, the magnetic field formation line 184 ma have various shapes configured to be symmetrical. with respect to the center of the shield 120

[0043] Further, the magnetic field formation line 184 may be positioned below the target 140 so that the magnetic field formation line 1.84 may be adjacent to the target 140. For example, the magnetic field formation line 184 may surround an upper portion of the outer sidewall of the shield 120. For example, the magnetic field formation line 184 may be positioned at or below the upper end of the outer sidewall of the shield 120. A current provided from the shield power supply 170 may flow through a region under the target 140.

[0044] The magnetic field formation line 184 may have a first connection point 186 and a second connection point 188. The first connection point 186 and the second connection point 188 may be symmetrical with each other with respect to the center of the shield 120. For example, the first connection point 186 and the second connection point 188 may be positioned on one straight line passing through the center of the shield 120, For example, the connection point 186 and the second connection point 188 may be respectively positioned at opposing portions of the shield 120. However, the first connection point 186 and the second connection point 188 might not be positioned on one straight line. For example, the second connection point 188 may be located on a. position shifted from the straight line by a predetermined angle.

[0045] In an example embodiment of the present inventive concept, the first connection point 186 may face and/or be substantially aligned with a portion of the shield 120 to which the first shield line 190 is connected to.

[0046] The magnetic field formation line 184 may be connected with the target power supply J60 through the first connection point 186 For example, the second power line 182 may be connected to the first connection point 186.

[0047] The magnetic field formation line 184 may be connected with the shield power supply 170 through the second connection point 188. A second. shield line 192 extended from the shield power supply 170 may be connected to the second connection point 188. The second shield line 192 may include a cable.

[0048] A ground line 194 may be connected to the second connection point 188 of the magnetic field formation line 184. For example, the ground line 194 may be connected to a lower structure 112 of the vacuum chamber 110. The ground line 194 may include a cable.

[0049] According to an example embodiinent of the present inventive concept, the magnetic. field formation line 184 may be s).fintnetrical with respect to the center of the shield 120 so that a magnetic field generated by the magnetic field formation line 184 may also have a symmetrical shape. Further, a direction of the current flowing through the annular magnetic field formation line 184 may be opposite to a direction of a flow of the shield current so that an asymmetrical magnetic field generated by the shield current mays be offset by the magneticheld generated by the annular magnetic field formation line 184.

[0050] Referring to FIG. 2, when a radius of the shield 120 may be “a”and a radius of the magnetic field formation line 184 may be “b”, a following equation may be established between the “a”and the “b” for showing the magnetic inducement effect and the magnetic field offSet effect by the magnetic field formation line 184 .

b=√{square root over (2)}.sub.a

[0051] Therefore, when the radius of the magnetic field formation line 184 may be about √{square root over (2)} times the radius of the shield 120, the above-mentioned effec may be shown. However, the is magnetic field formation line 184 may show the effects when the radius of the magnetic field formation line 184 may be about √{square root over (2±)}√{square root over (2)}×20% times the radius of the shield 120,

[0052] Comparing a Conventional PVD Apparatus According to a Comparative Example and the PVD Apparatus According to an Example Embodiment of the Present Inventive Concept

[0053] FIG. 3 is a cross-sectional view illustrating a conventional PVD apparatus in accordance with a comparative example.

[0054] The conventional PVD apparatus in FIG. 3 may include elements substantially the same as those of the PVD apparatus in FIG. 1 except for a connection structure between the target power supply and the shield power supply. Thus, the same reference numerals may refer to the same elements and any further illustrations or discussion with respect to the same elements may, be omitted herein for brevity,

[0055] Referring to FIG. 3, the target, power supply 160 may be connected with the target 140 through a first power line 180a. A second power line 182a extended from the target power supply 160 may be grounded to the lower structure 112 of the vacuum chamber 110 by crossing over one sidewall of the vacuum chamber 110. The shield power supply 170 may he connected with the shield 120 through a first shield line I90a. A second shield line 192a extended from the shield power supply 170 may he grounded to the lower structure 112 of the vacuum chamber 110. That is, the conventional PVD apparatus according to a comparative example might not include the annular magnetic field formation line 184 in FIG. 1.

[0056] FIG. 4 is a graph showing magnetic field components formed in the conventional PVD apparatus in FIG. 3 according to a comparative example, In FIG. 4, a line {circle around (1)} may represen components of a magnetic field and a line {circle around (2)} may represent v components of the magnetic field.

[0057] As shown in FIG. 4, it can be noted that an average value of the y components of the magnetic field caused by a shield current in accordance with a rotationof the magnet may be a positive number. Thus, they components of the magnetic field may be deflected in left and right directions so that. the magnetic field may have an asymmetrical shape.

[0058] FIG. 5 is a graph showing, magnetic field components formed by a magi tic field formation line of the PVD apparatus in FIG. 1 according to an example embodiment of the present inventive concept. In FIG. 5, a line {circle around (3)} may represent x components of a magnetic field and a line {circle around (4)} may represent y components of the magnetic field.

[0059] As shown in FIG. 5, it can be noted that the y components of the magnetic field formed by the magnetic field formation line may have a constant value of about zero, and the x components of the magnetic field may have a constant valne of about 1.2.

[0060] FIG. 6 is a graph showing magnetic field components formed in the PVD apparatus in FIG: I by the magnetic field components in FIG. 5. In FIG. 6, a line {circle around (5)} may represent the components of the magnetic field and a line {circle around (6)} may represent the v conA one nts magnetic field.

[0061] As shown in FIG. 6, it can be noted that an average value of the y components of the magnetic field may be about zero. Thus, the magnetic field in FIG. 5 formed by the annular magnetic field formation line may offset the magnetic field in FIG. 4 formed by the shield current. As a result, it can be noted that the annular magnetic field formation line may form the symmetrical magnetic field.

[0062] FIG. 7 is an image showing a magnetic field formed by the conventional PVD apparatus in FIG. 3, and FIG. 8 is an image showing a magnetic field formed by a magnetic field formation line of the PVD apparatus in FIG. 1 according to an example embodiment of the present inventive concept.

[0063] As shown in FIG. 7, it can be. noted that the magnetic field formed by the shield current in accordance with the rotation of the magnet may be deflected to the left.

[0064] In contrast, as shown in FIG. 8 it can the noted that the magnetic field formed by the annular magnetic field formation line may have the symmetrical shape.

[0065] FIG. 9 is an Mage showing a distribution of plasma in the conventional PVD apparatus in FIG. 3 according to a comparative example, and FIG. 10 is an image showing a distribution of plasma in the PVD apparatus in FIG. 1 according to an example embodiment of the present inventive concept.

[0066] As shown in FIG. 9, it can be noted that the magnetic -field formed M the conventional PVD apparatus may he excessively deflected right. Thus, it can also be noted that plasma induced by the asymmetrical magnetic field may also be excessively deflected right.

[0067] In contrast, as shown in FIG. 10, because the annular magnetic field formation line may form the symmetrical magnetic field, it can be noted that the plasma induced by the symmetrical magnetic field may have a substantially uniform distribution.

[0068] FIG. 11 is an image showing a thickness distribution of a layer on a substrate using the conventional PVD apparatus in FIG. 3 according to a comparative example, and FIG. 12 is an image showing a thickness distribution of a layer on a substrate using the PVD apparatus in FIG. 1 according to an example embodiment of the present inventive concept.

[0069] As shown in FIG. 11, it can be noted that a thickness of a portion on the right side of a layer deposited on the semiconductor substrate may he thicker than a thickness of a portion on the left side of the layer dtae to the plasma induced by the asymmetrical magnetic field.

[0070] In contrast, as shown in FIG. 12, it can be noted that a layer deposited on the semiconductor substrate may have a substantially unifbrm thickness due to the plasma induced by the symmetrical magnetic field.

[0071] FIG. 13 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept, and FIG. 14 is a cross-sectional view taken along a line B-B′ in FIG. 13.

[0072] A PVD apparatus 100a according to an example embodiment of the present inventive concept may include elements substantially the same as those of the PVD apparatus 100 in FIG. 1 except for a magnetic field formation fine. Thus, the same reference numerals may refer to the same elements and any further illustrations or discussion with respect to the same elements may be omitted herein for brevity.

[0073] Referring to FIGS. 13 and 14, a magnetic field formation line may include a conductive ring 184a configured to surround the outer sidewall of the vacuum chamber 110. For example, the conductive ring 184a may make contact with the outer sidewall of the vacuum chamber 110. In an example embodiment of the present inventive concept, the conductive ring 184a may include flange integrally formed with the outer sidewall of the vacuum chamber 110. The second power line 182 may be connected to the first connection point I86a of the conductive ring 184a. Thus: the conductive ring 184a may be electrically connected with the target power supply 160. The second shield line 192 extended from the shield power supply 170 may be connected to the second connection point 188a of the conductive ring; 184a. The ground line 194 may be connected to the second connection point 188a of the conductive ring 184a.

[0074] FIG. 15 is a cross-sectional view illustrating, a PVD apparatus in accordance with an example embodiment of the present inventive concept.

[0075] A PVD apparatus 100b of example embodiments may include elements substantially the same as those of the PVD apparatus 100 in FIG. 14 except for a conductive ring. Thus, the same reference numerals may refer to the same elements and any further illustrations or discussion with respect to the same elements may be omitted herein for brevity.

[0076] Referring to FIG. 15, a conductive ring 184b may be spaced apart from the outer sidewall of the vacuum chamber 110. Thus, a space may be formed between the conductive ring 184b and the outer sidewall of the vacuum chamber 110. The conductive ring 184b may be fixed to the lower structure 112 of the vacuum chamber 110.

[0077] FIG. 16 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept, and FIG. 17 is a cross-sectional view taken along a line C-C′ in FIG. 16.

[0078] A PVD apparatus 100c according to an example embodiment of the present inventive concept may include elements substantially the same as those of the PVD apparatus 100 in FIG 1 except for a magnetic field formation line. Thus, the same reference numerals may refer to the same elements and any further illustrations or discussion with respect to the same elements may he omitted herein for brevity.

[0079] Referring to FIGS. 16 and 17, a vacuum chamber 110 may include a conductive material. For example, the vacuum chamber 110 may include a metal.

[0080] The second power line 182 extended from the target power supply 160 may be connected to a fust portion 114 of the outer sidewall of the vacuum chamber 110. The second shield line 192 extended from the shield power supply 170 may he connected to a second portion 116 of the outer sidewall of the tiacuu chamber 110. The first portion 114 and the second portion 116 of the vacuum chamber 110 may he symmetrical with respect to the center of the shield 120. For example, the first portion 114 may be at a position opposing that of the second portio 116.

[0081] Therefore, the annular sidewall of the vacuum chamber 110 including the conductive material may have the functions of the magnetic field formation line 184 in FIG. 1.

[0082] FIG. 18 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept.

[0083] A PVD apparatus 100d according to an example embodiment of the present inventive concept may include elements substantially the same as those of the PVD apparatus 100 in FIG. 1 except for not including a shield power supply. Thus, the same reference numerals may refer to the same elements and any further illustrations or discussion with respect to the same elements may be omitted herein for brevity.

[0084] Referring to FIG. 18, the PVD apparatus 100d according to an example embodiment of the present inventive concept might not include the shield power supply. Thus, the shield voltage might not be applied to the shield 120. Therefore, the PVD apparatus 100d might not include a first shield line, which is connected to the shield power supply 170 and the shield 120, and a second shield line, which is connected to the shield power supply 170 and the second point 188 of the magnetic field formation line 184.

[0085] FIG. 19 is a cross-sectional view illustrating a PVD apparatus in accordance with an example embodiment of the present inventive concept.

[0086] A PVD apparatus I 00e according to an example embodiment of the present inventive concept may include elements substantially the same as those of the PVD apparatus 100 in FIG. 1 and may further include a collimator. Thus, the same reference numerals may refer to the same elements and any further illustrations or discussion with respect to the same elements may be omitted herein for brevity.

[0087] Referring to FIG. 19, a cc llimator 200 may be arranged between the target 140 and the pedestal 130. The collimator 200 may have a substantially uniform thickness. The collimator 200 may have a plurality of passages 202. The deposition material released from the target 140 may partially pass through the passages 202 of the collimator 200 to filter the deposition material.

[0088] In an example embodiment of the present inventive concept, the PVD apparatuses according to an example embodiment of the present inventive concept may further include a magnetic field generation module for controlling the plasma and ions.

[0089] According to an example embodiment of the present inventive concept, the magnetic field formation line may be configured to surround the shield so that the magnetic field formation line may be symmetrical with respect to the center of the shield. Thus, a symmetrical magnetic field may be formed from the symmetrical magnetic field formation line. As a result, the symmetrical magnetic field may distribute the plasma in a substantially unifomi manner to form a layer having a substantially uniform thickness on the substrate.

[0090] It is to be understood that in the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.

[0091] While the present inventive concept has been described with reference to example embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made thereto without departing from the spirit and scope of the present inventive concept.