JP2009050943A - Retainer ring, carrier head and chemical mechanical polishing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retainer ring reducing generation of micro scratches due to cracks of the retainer ring, and also to provide a carrier head and a chemical mechanical polishing apparatus. <P>SOLUTION: The retainer ring 110 is placed around a wafer 10 to be polished on a polishing pad 32 of a CMP apparatus. The retainer ring 110 has a chamfered part 181 having tapered- or curved-chamfered corners of an inner side face 188 extending along the rim of the wafer 10 and a bottom face 182 opposite to the polishing pad 32. The height h<SB>1</SB>of the chamfered part 181 with a plane including the bottom face 182 as reference is 1/4 or less of the thickness of the wafer 10 to be polished. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a retainer ring, a carrier head, and a chemical mechanical polishing apparatus.

  Along with the high integration and high performance of semiconductor devices, the structure of semiconductor devices is miniaturized and multilayered. In order to realize miniaturization and multilayering of semiconductor devices, it is required that the surface of a wafer serving as a substrate of the semiconductor device has high flatness.

  Chemical mechanical polishing (CMP) is one method for increasing the flatness of the wafer surface. An apparatus for performing CMP includes, for example, a polishing pad, a carrier head that holds and presses a wafer, and a slurry supply nozzle. Further, the carrier head is constituted by a retainer ring that surrounds the outer periphery of the wafer and an elastic film that presses the upper surface of the wafer. The retainer ring surrounds the outer periphery of the wafer and prevents the wafer from jumping out.

As such a retainer ring, for example, a metal ring and an engineering plastic ring are superimposed (see, for example, Patent Document 1). In other words, the engineering plastic ring surrounding the outer periphery of the wafer is reinforced with a metal ring to increase the rigidity of the entire retainer ring.
Japanese Patent No. 3431599

  When polishing a wafer with a CMP apparatus, it is required to minimize the generation of fine scratches on the wafer surface, that is, micro scratches. This is because when the number of micro scratches on the wafer surface increases, the yield of semiconductor devices fabricated on the wafer decreases.

  However, when a wafer is polished using the CMP apparatus having the above-described configuration, an excessive number of micro scratches is sometimes observed. Therefore, the present inventor tried to elucidate the mechanism by which micro scratches occur on the wafer surface when the wafer is polished. As a result, the outer edge of the wafer slightly expanded in diameter by the centrifugal force accompanying the rotation of the carrier head is in contact with the retainer ring. When a retainer ring made of a material such as engineer plastic is used, the inner surface of the retainer ring It was found that a part of the retainer ring was sharpened and lost after sharpening, resulting in a piece, which caused microscratching.

  FIGS. 7A to 7D are diagrams conceptually showing a process in which a retainer ring fragment is generated. Initially, as shown in FIG. 7A, the inner side surface 201 of the retainer ring 200 that is flat along the thickness direction of the wafer W is used when the wafer W is polished as shown in FIG. The outer edge portion of the wafer W comes into contact and wears, and a dent H is gradually formed. When the depth of the recess H reaches a certain level after repeated use of the CMP apparatus (FIG. 7C), the lower end portion 202 of the retainer ring 200 sharpened with the formation of the recess H is missing. Eventually (FIG. 7 (d)), the fragments are mixed into the slurry. Then, microscratches are generated when this piece damages the wafer W. In addition, since the thickness of the wafer is generally about 0.8 [mm], the actual dent and defect mark of the retainer ring 200 are as fine as several hundred micrometers and cannot be confirmed with the naked eye. The problem described above has been found by continuously observing changes in the inner surface of the retainer ring using a microscope.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a retainer ring, a carrier head, and a chemical mechanical polishing apparatus that can reduce the generation of microscratches due to a retainer ring fragment.

  In order to solve the above-described problems, a retainer ring according to the present invention is a retainer ring disposed around a wafer to be polished on a polishing pad of a chemical mechanical polishing apparatus, and an inner surface along an outer edge of the wafer. And a bottom surface facing the polishing pad has a chamfered portion chamfered in a tapered shape or a curved surface.

  As shown in FIGS. 7C and 7D, the retainer ring piece is generated by sharpening the corners of the inner surface and the bottom surface of the retainer ring. The present inventor has found that if this corner is chamfered in a tapered shape or a curved surface in advance, sharpening can be prevented and generation of fragments can be reduced. That is, according to the above-described retainer ring, it is possible to effectively reduce the generation of micro scratches due to the retainer ring piece.

  The retainer ring may be characterized in that the height of the chamfered portion based on a plane including the bottom surface is ¼ or less of the thickness of the wafer to be polished. Since the retainer ring surrounds the outer periphery of the wafer and prevents the wafer from jumping out, if the height from the bottom surface of the chamfered portion is excessive, the wafer is likely to jump out of the retainer ring. As a result of trial and error by the present inventors, it has been found that if the height of the chamfered portion based on the plane including the bottom surface is ¼ or less of the thickness of the wafer, the protrusion of the wafer can be suitably prevented. That is, according to this retainer ring, it is possible to effectively reduce the occurrence of microscratches due to retainer ring fragments without impairing the original function of preventing the wafer from popping out.

  Further, when CMP is performed on a wafer, in order to make the wafer surface as flat as possible, it is general to adjust the polishing conditions such as the components of the slurry and the rotation speed to be optimum conditions. If the inner diameter of the retainer ring changes, it is necessary to readjust the polishing conditions. Since the height of the chamfered portion is ¼ or less of the thickness of the wafer as in the retainer ring described above, the occurrence of micro scratches can be reduced without substantially changing the inner diameter of the retainer ring with respect to the wafer. Adjustment work can also be reduced.

  Further, the retainer ring may be characterized in that the height of the chamfered portion is 0.2 [mm] or less. The thickness of the wafer to be polished is generally 0.8 [mm]. In this case, when the height of the chamfered portion is 0.2 [mm] or less, the wafer can be protruded from the retainer ring. It can prevent suitably.

  The retainer ring may be characterized in that the height of the chamfered portion is 1/8 of the thickness of the object to be polished. As a result, it is possible to more effectively reduce the occurrence of micro scratches due to retainer ring fragments while preventing the wafer from popping out more reliably.

  The carrier head according to the present invention has any of the above-described retainer rings, and rotates while holding the wafer to be polished on the polishing pad of the chemical mechanical polishing apparatus inside the retainer ring and pressing the wafer against the polishing pad. It is characterized by that. According to this carrier head, by having any one of the above-described retainer rings, it is possible to effectively reduce the generation of micro scratches due to the retainer ring pieces.

  A chemical mechanical polishing apparatus according to the present invention is a chemical mechanical polishing apparatus for performing chemical mechanical polishing on a wafer, and includes a polishing pad and any one of the above-described retainer rings, and the wafer is disposed inside the retainer ring. And a carrier head that rotates while being pressed against the polishing pad. According to this chemical mechanical polishing apparatus, by having any one of the above-described retainer rings, it is possible to effectively reduce the occurrence of micro scratches due to the retainer ring pieces.

  According to the retainer ring, the carrier head, and the chemical mechanical polishing apparatus according to the present invention, it is possible to reduce the occurrence of micro scratches due to the retainer ring piece.

  Hereinafter, embodiments of a retainer ring, a carrier head, and a chemical mechanical polishing (CMP) apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

<Embodiment>
FIG. 1 is an exploded perspective view showing a configuration of an embodiment of a CMP apparatus according to the present invention. In the CMP apparatus 20 of this embodiment, CMP is performed on one or more disk-shaped wafers 10. The CMP apparatus 20 has a lower machine base 22, and the lower machine base 22 has a flat table 23. On the table 23, a plurality of polishing units 25 a, 25 b and 25 c and a transport unit 27 for transporting the wafer 10 are provided.

  Each of the polishing units 25 a to 25 c has a circular rotary platen 30, and a polishing pad 32 is installed on each rotary platen 30. If the diameter of the wafer 10 is 8 inches (203 [mm]) or 12 inches (305 [mm]), the diameters of the rotating surface plate 30 and the polishing pad 32 are about 20 inches (508 [mm]) or 30 respectively. Inch (762 [mm]). The rotary platen 30 is connected to a rotary plate drive motor (not shown) disposed in the lower machine base 22. The turntable drive motor rotates the rotating platen 30 at a speed of, for example, 30 to 200 revolutions per minute, but may be slower or faster. Each of the polishing units 25 a to 25 c may further include a corresponding pad conditioner device 40 in order to maintain the polishing conditions of the polishing pad 32.

  The slurry (abrasive) 50 is supplied to the surface of the polishing pad 32 by the slurry supply arm 52. The slurry 50 includes a reactant (eg, deionized water) and a chemical reaction catalyst (eg, potassium hydroxide). The slurry 50 may further include abrasive particles (for example, silicon dioxide). A sufficient amount of the slurry 50 is supplied so as to spread throughout the polishing pad 32. The slurry supply arm 52 has several spray nozzles (not shown) for supplying a cleaning liquid to the polishing pad 32 when the polishing operation is completed.

  The multi-head carousel 60 is installed above the lower machine base 22. The multi-head carousel 60 has a carrier head support portion 66 and a cover 68, and the carrier head support portion 66 is rotatably supported by a rotating shaft 62. The rotation shaft 62 is connected to a motor disposed in the lower machine base 22, and the carrier head support portion 66 rotates around the central axis 64. The multi-head carousel 60 has four carrier head devices 70 a, 70 b, 70 c and 70 d arranged at equal angles around the central axis 64. The carrier head devices 70 a to 70 d move with the rotation of the carrier head support portion 66. The carrier head devices 70 a to 70 d first receive the wafer 10 from the transport unit 27. Then, the wafer 10 is polished by pressing the wafer 10 against the polishing pad 32 of the polishing units 25 a to 25 c while holding the wafer 10. After the polishing operation is completed, the wafer 10 is sent to the transport unit 27.

  Each of the carrier head devices 70 a to 70 d has a carrier head 100. Each carrier head 100 rotates independently around the central axis of the carrier head 100 and is independent along a slot 72 formed in the carrier head support portion 66 with the direction intersecting the central axis 64 as the longitudinal direction. Then go back and forth in the horizontal direction. A carrier driving shaft 74 that supports and rotates the carrier head 100 is attached to the carrier head 100. The carrier drive shaft 74 extends through the slot 72 and is connected to the carrier head rotation motor 76. The carrier drive shaft 74 and the carrier head rotation motor 76 are placed on a slider (not shown) that is linearly driven along the slot 72 by the radial drive motor to reciprocate the carrier head 100 horizontally. It may be supported.

  When performing the polishing operation, each carrier head 100 lowers the wafer 10 to contact the polishing pad 32. In general, the carrier head 100 holds the wafer 10 at a predetermined position with respect to the polishing pad 32 and distributes the pressing force over the entire back surface of the wafer 10. The carrier head 100 also transmits torque from the carrier drive shaft 74 to the wafer 10.

  FIG. 2 is a side sectional view showing the structure of the carrier head 100. As shown in FIG. 2, the carrier head 100 includes a housing 102, a base 104, a gimbal mechanism 106, a loading chamber 108, a retainer ring 110, and a wafer backing assembly 112.

  The housing 102 is connected to a carrier drive shaft 74 (see FIG. 1) so as to be rotatable around a rotation axis 107 that is substantially perpendicular to the surface of the polishing pad 32 (see FIG. 1). The loading chamber 108 is disposed between the housing 102 and the base 104 so as to apply downward pressure to the base 104. The vertical position of the base 104 with respect to the polishing pad 32 is also controlled by the loading chamber 108. A cylindrical bushing 122 is inserted through a guide hole 124 formed in the housing 102.

  The wafer backing assembly 112 includes a perforated disk-like support structure 114, a flexible diaphragm 116 that connects a frame portion of the support structure 114 to the base 104, and an elastic film 118 that is attached to cover the lower surface of the support structure 114. And have. A chamber 190 is provided between the base 104 and the wafer backing assembly 112. When the chamber 190 is pressurized, the elastic film 118 is pressed downward and the wafer 10 in contact with the elastic film 118 (FIG. 1). Is pressed against the polishing pad 32.

  The housing 102 is formed in a substantially disc shape so as to correspond to the circular contour of the wafer 10 to be polished. Two flow paths 126 and 128 are formed in the housing 102 for air control of the carrier head 100. The base 104 is an annular member located below the housing 102. The base 104 may be constructed of a rigid material such as aluminum, stainless steel or plastic reinforced with fibers. A flow path 130 is formed inside the base 104, and the flow path 128 and the flow path 130 are connected to each other by piping (not shown) attached to the fixtures 132 and 134. An elastic membrane 140 is attached to one end of the flow path 130 on the lower surface of the base 104 via a clamp ring 142. The elastic membrane 140 forms a bag-like portion (bladder) 144, and the downward pressure on the support structure 114 and the elastic membrane 118 is controlled by adjusting the amount of gas supplied to the bag-like portion 144. .

  The gimbal mechanism 106 is a member that supports the base 104. The gimbal mechanism 106 pivotally supports the base 104 relative to the housing 102 such that the base 104 is substantially parallel to the surface of the polishing pad 32 (FIG. 1). The gimbal mechanism 106 includes a cylindrical gimbal shaft 150 and a disc-shaped bending ring 152. One end of the gimbal shaft 150 is connected to the flow path 154, and the other end is fixed to the center portion of the bending ring 152. The base 104 is fixed to the outer peripheral portion of the bending ring 152. The gimbal shaft 150 can slide vertically to allow the base 104 to move vertically and also fixes the lateral position of the base 104 relative to the housing 102.

  A gap between the housing 102 and the base 104 is sealed with an annular diaphragm 160. Specifically, the inner edge of the diaphragm 160 is clamped to the housing 102 by the clamp ring 162, and the outer edge of the diaphragm 160 is clamped to the base 104 by the clamp ring 164. Thereby, the loading chamber 108 is configured to be airtight. The diaphragm 160 is made of, for example, an annular silicon thin plate.

  The support structure 114 of the wafer backing assembly 112 is disposed below the base 104. The support structure 114 includes a support plate 170, a lower annular clamp 172, and an upper annular clamp 174. The support plate 170 is a disc-shaped rigid member having a plurality of through holes 176. The support plate 170 may further have a lip 178 projecting downward at its outer edge. Further, the bending diaphragm 116 of the wafer backing assembly 112 is a member formed in an annular shape using a flexible material. The outer edge of the flexible diaphragm 116 is clamped between the base 104 and the retainer ring 110, and the inner edge of the flexible diaphragm 116 is clamped between the lower clamp 172 and the upper clamp 174. The flexible diaphragm 116 is made of a composite material such as rubber, such as neoprene, or a fabric coated with an elastomer such as nylon (registered trademark) or Nomex (registered trademark), plastic, or glass fiber.

  The elastic film 118 is a circular thin plate formed of a flexible and elastic material such as chloroprene or ethylene / propylene / rubber. A portion of the elastic membrane 118 extends around the edge of the support plate 170 so as to be clamped between the support plate 170 and the lower clamp 172. The chamber 190 is hermetically sealed by the elastic film 118, the support structure 114, the flexure diaphragm 116, the base 104, and the gimbal mechanism 106.

  The retainer ring 110 is an annular member that is disposed around the wafer 10 on the polishing pad 32 and surrounds the outer periphery of the wafer 10 to prevent the wafer 10 from jumping out. The retainer ring 110 is fixed to the outer edge of the base 104 by bolts 194, for example. As fluid is pumped into the loading chamber 108 and the base 104 is pushed down, the retainer ring 110 is also pushed down to load the polishing pad 32. The inner side surface 188 of the retainer ring 110 and the surface 120 of the elastic film 118 constitute a recess for accommodating the wafer. The retainer ring 110 prevents the wafer 10 from jumping out of the recess.

  FIG. 3A is a side cross-sectional view showing an enlarged configuration near the retainer ring 110. FIG. 3B is a side sectional view showing the contact portion between the retainer ring 110 and the wafer 10 further enlarged. As shown in FIG. 3A, the retainer ring 110 has an annular first portion 180, an annular shape that is concentric and the same diameter as the first portion 180, and is stacked and fixed on the first portion 180. Second portion 184 formed. The first portion 180 has a bottom surface 182 that contacts the polishing pad 32 during a polishing operation, and an inner surface 188 along the outer edge of the wafer 10. Further, the second portion 184 is fixed to the base 104. The first portion 180 may be bonded to the second portion 184 via an adhesive layer 186, for example.

  The first portion 180 is composed of a material that is chemically inert to the slurry used in the CMP process. Further, the first portion 180 is required to have an appropriate hardness in order to obtain a certain degree of wear resistance. On the other hand, the first portion 180 is not damaged when the wafer 10 contacts the retainer ring 110. The first portion 180 is required to be softer than the wafer 10. Specifically, as the material of the first portion 180, for example, polyphenylene sulfide (PPS) such as Tektron (registered trademark) manufactured by DSM Engineering Plastics, Inc. can be used. In addition, Delrin (registered trademark), polyethylene terephthalate (PET), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), or DuPont ZYMAXX (registered trademark) manufactured by DuPont, USA. Other plastic materials such as composites are also suitable. The first portion 180 is produced by cutting out a predetermined shape from the lump of plastic material.

The thickness T ₁ of the first portion 180 is formed to be thicker than the thickness T _S of the wafer 10 such that the wafer 10 does not touch the adhesive layer 186. The bottom surface 182 of the first portion 180 may be substantially flat or has a groove that extends from the outer surface to the inner surface to facilitate transfer of the slurry from the outside to the inside of the retainer ring 110. May be.

The second portion 184 is made of metal. As a constituent material of the second portion 184, for example, a rigid material such as stainless steel, molybdenum, aluminum, ceramics, or alumina is suitable. The thickness T ₂ of the second portion 184 is preferably formed to be thicker than the thickness T ₁ of the first portion 180.

  Here, as shown in an enlarged view in FIG. 3B, the first portion 180 has a chamfered portion 181 in which the angle between the inner surface 188 and the bottom surface 182 is chamfered in a tapered shape (slope shape). ing. The chamfered portion 181 is formed by cutting the corner portion of the first portion 180, for example. An angle (inclination angle) formed by the bottom surface 182 and the chamfered portion 181 is, for example, 45 °. In addition, this inclination angle may be set to an arbitrary angle within a range of 30 ° to 60 °, for example.

The height h ₁ of the chamfered portion 181 with respect to the plane including the bottom surface 182 is ¼ or less of the thickness T _S of the wafer 10, and more preferably ８ of the thickness T _S. Since the thickness T _S of the wafer 10 is generally 0.8 [mm], the height h ₁ of the chamfered portion 181 is 0.2 [mm] or less, preferably 0.1 [mm]. Further, the chamfered portion 181 is formed by significantly cutting the corners of the inner side surface 188 and the bottom surface 182 as described above, and the shape caused by the tolerance when the retainer ring is formed is Different. That is, the shape similar to the chamfered portion 181 that is caused by processing tolerance is a very small height from the bottom surface 182 of less than 0.01 [mm]. The chamfered portion 181 has a height h ₁ from the bottom surface 182 of 0.01 [mm] or more (preferably 0.05 [mm] or more), and is clearly distinguished from such a shape.

  According to the retainer ring 110 having such a configuration, the following effects can be obtained. As shown in FIGS. 7C and 7D, the retainer ring piece tends to be generated by sharpening the corners of the inner surface and the bottom surface of the retainer ring. Therefore, the present inventor has thought that by chamfering the corners in a tapered shape, sharpening can be prevented and generation of fragments can be reduced. That is, when the chamfered portion 181 is formed at the corner between the inner surface 188 and the bottom surface 182 of the retainer ring 110 as shown in FIG. 4A, the outer edge of the wafer contacts the inner surface 188 when the wafer is polished. By doing so, a recess H is formed adjacent to the chamfered portion 181. The recess H gradually increases as the use of the CMP apparatus 20 is repeated (FIG. 4C), but the sharpened portion has already been chamfered and removed, so that the fragment as shown in FIG. 202 does not occur. Therefore, according to the retainer ring 110 of the present embodiment, the generation of fragments can be prevented and the generation of micro scratches can be effectively reduced.

FIG. 5 shows three wafers A1 to A3 actually subjected to CMP using the retainer ring 110 having the chamfered portion 181 and 10 sheets subjected to CMP using the retainer ring without the chamfered portion for comparison. 4 is a graph showing the number of micro scratches after CMP in each of wafers B1 to B10. In the wafers A1 to A3, the height h ₁ of the chamfered portion 181 is set to 1/8 of the thickness T _S of the wafer 10. Further, PPS was used as the material of the first portion 180 of the retainer ring 110. As wafers A1 to A3 and B1 to B10, wafers having a copper film formed thereon were used. As shown in FIG. 5, when the retainer ring without a chamfered portion was used (wafers B1 to B10), a large number of micro scratches per wafer exceeding 500 appeared. In addition, some of the micro scratches (wafer B6, etc.) existed because the retainer ring was still new and the deep recess H as shown in FIG. 7C was not formed. Conceivable. On the other hand, when the retainer ring 110 formed with the chamfered portion 181 is used (wafers A1 to A3), the number of micro scratches per wafer is 300 in spite of having passed a sufficient number of times. The effect mentioned above by the chamfered part 181 appears well.

Since the retainer ring 110 surrounds the outer periphery of the wafer 10 and prevents the wafer 10 from jumping out, if the height h ₁ of the chamfered portion 181 is excessive, the wafer 10 is likely to jump out of the retainer ring 110. . In this regard, the present inventor has a retainer ring height h ₁ has a chamfer which is 3/8 of the thickness T _S of the wafer 10, which is 1/4 of the height h ₁ is the thickness T _S chamfered A retainer ring having a portion was made as a prototype and subjected to CMP. As a result, when the height h ₁ is 3/8 of the thickness T _S , the wafer sometimes jumps out, but when the height h ₁ is 1/4 of the thickness T _S , the wafer is I didn't jump out at all. Thus, it has been found that if the height h ₁ of the chamfered portion 181 is ¼ or less of the thickness of the wafer 10, the protrusion of the wafer 10 can be suitably prevented. That is, according to the retainer ring 110 of the present embodiment, the height h ₁ of the chamfered portion 181 is ¼ or less of the thickness of the wafer 10, thereby impairing the original function of preventing the wafer 10 from popping out. In addition, it is possible to effectively reduce the generation of micro scratches due to the fragments of the retainer ring 110.

According to the inventor's experience, the height h ₁ of the chamfered portion 181 is preferably approximately 1/8 of the thickness T _S of the wafer 10. In this case, it is possible to effectively reduce the occurrence of microscratches due to the fragments of the retainer ring 110 while more reliably preventing the wafer 10 from jumping out.

Further, when CMP is performed on the wafer 10, in order to make the surface of the wafer 10 as flat as possible, the polishing conditions such as the slurry components and the rotation speed are generally adjusted to be optimum conditions. Then, when the inner diameter of the retainer ring 110 changes, it is necessary to readjust the polishing conditions. In the retainer ring 110 of this embodiment, the height h ₁ of the chamfered portion 181 is ¼ or less of the thickness T _S of the wafer 10, and the inner diameter of the retainer ring 110 viewed from the wafer 10 is not substantially changed. Generation of micro scratches can be reduced. Therefore, the labor for readjustment can also be reduced.

  Note that the effects of the retainer ring 110 described above are the same in the carrier head 100 on which the retainer ring 110 is mounted and the CMP apparatus 20 including the carrier head.

<Modification>
FIG. 6 is a side sectional view showing another example of the chamfered portion formed on the retainer ring 110. As shown in FIG. 6, the chamfered portion 183 according to this modification is formed by chamfering the corners of the inner surface 188 and the bottom surface 182 of the first portion 180 into a curved surface. The chamfered portion 183 is formed by cutting the corner portion of the first portion 180, for example. The shape of the chamfered portion 183 in the cross section including the central axis of the retainer ring 110 is a curved shape that protrudes obliquely downward, and its radius of curvature is arbitrary. Further, the height h ₂ of the chamfered portion 183 based on the plane including the bottom surface 182 of the first portion 180 is ¼ or less of the thickness T _S of the wafer 10, more preferably 1 of the thickness T _S. / 8. Since the thickness T _S of the wafer 10 is generally 0.8 [mm], the height h ₂ of the chamfered portion 183 is 0.2 [mm] or less, preferably 0.1 [mm]. Further, like the chamfered portion 181 shown in FIG. 3B, the chamfered portion 183 is formed by significantly cutting the corner portions of the inner side surface 188 and the bottom surface 182 and forms a retainer ring. It differs from the shape produced by the tolerance. The chamfered portion 183 has a height h ₂ from the bottom surface 182 of 0.01 [mm] or more (preferably 0.05 [mm] or more), and is clearly distinguished from such a shape.

  The chamfered portion of the retainer ring is not limited to the tapered shape as shown in FIG. 3B, and may be formed in a curved shape as in this modification. Thereby, the effect mentioned above by a chamfering part can be obtained similarly.

  The retainer ring, the carrier head, and the chemical mechanical polishing apparatus according to the present invention are not limited to the above-described embodiments, and various other modifications are possible. For example, in the above embodiment, the example in which the present invention is applied to the retainer ring including the first portion made of plastic and the second portion made of metal has been described. However, the present invention is not limited to the retainer ring having such a configuration. It can also be applied to a retainer ring constituted by a single part or three or more parts. Further, the constituent material of the retainer ring in which the chamfered portion is formed is not limited to plastic, but may be other materials.

1 is an exploded perspective view showing a configuration of an embodiment of a CMP apparatus according to the present invention. It is side surface sectional drawing which shows the structure of a carrier head. (A) It is side surface sectional drawing which expands and shows the structure of a retainer ring vicinity. (B) It is side surface sectional drawing which expands further and shows the contact part of a retainer ring and a wafer. (A)-(c) It is a figure for demonstrating the effect by the chamfering part formed in the retainer ring. Three wafers A1 to A3 actually subjected to CMP using the retainer ring formed with the chamfered portion, and ten wafers B1 to B10 subjected to CMP using the retainer ring without the chamfered portion for comparison. It is a graph showing the number of micro scratches after CMP in each. It is side surface sectional drawing which shows the other example of the chamfering part formed in a retainer ring. (A)-(d) It is a figure which shows the mechanism in which the fragment | piece which causes a micro scratch in the conventional retainer ring generate | occur | produces.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Wafer, 20 ... Chemical mechanical polishing apparatus, 25a-25c ... Polishing part, 27 ... Conveyance part, 30 ... Rotary platen, 32 ... Polishing pad, 40 ... Pad conditioner apparatus, 50 ... Slurry, 60 ... Multiple head carousel, 70a to 70d ... carrier head device, 100 ... carrier head, 102 ... housing, 104 ... base, 106 ... gimbal mechanism, 110 ... retainer ring, 180 ... first part, 181, 183 ... chamfered part, 182 ... bottom face, 184 ... 2nd part, 186 ... adhesive layer, 188 ... inner surface.

Claims (6)

A retainer ring disposed around a wafer to be polished on a polishing pad of a chemical mechanical polishing apparatus,
A retainer ring comprising a chamfered portion having a chamfered or curved surface between an inner side surface along an outer edge of the wafer and a bottom surface facing the polishing pad.   The retainer ring according to claim 1, wherein a height of the chamfered portion with respect to a plane including the bottom surface is ¼ or less of a thickness of the wafer to be polished.   The retainer ring according to claim 1, wherein a height of the chamfered portion is 0.2 [mm] or less.   The retainer ring according to claim 1, wherein a height of the chamfered portion is 1/8 of a thickness of the object to be polished.   5. The retainer ring according to claim 1, wherein the wafer to be polished is held inside the retainer ring on the polishing pad of the chemical mechanical polishing apparatus and is rotated while being pressed against the polishing pad. A carrier head, characterized by: A chemical mechanical polishing apparatus for performing chemical mechanical polishing on a wafer,
A polishing pad;
A retainer ring according to any one of claims 1 to 4, and a carrier head that rotates while holding the wafer inside the retainer ring and pressing the wafer against the polishing pad. Chemical mechanical polishing equipment.

Images