Chemical mechanical polishing apparatus

Abstract

The application provides a chemical mechanical polishing device, which belongs to the polishing technical field and comprises a polishing head carrier, an elastic film structure and a compression ring structure. In the polishing process, the air chamber structure on the elastic film is increased in air pressure, the air chamber structure exerts a certain pressure on the substrate, the abutting portion on the compression ring structure abuts against the air chamber structure and limits the expansion of the air chamber structure in the direction away from the substrate during the pressure increasing process, the air chamber structure at the edge can be limited to expand in the direction away from the substrate through the arranged compression ring structure, the pressure distribution of the air chamber structure on the substrate is more uniform, and the polishing effect of the substrate is improved.

Description

Technical Field

[0001] This invention relates to the field of polishing technology, and more specifically to a chemical mechanical polishing apparatus. Background Technology

[0002] With increasing requirements for semiconductor substrate flatness and decreasing edge margins, the demands for high flatness, uniformity, and consistency of substrate edges are becoming increasingly stringent in chemical mechanical polishing (CMP) processes. Current polishing equipment achieves substrate polishing by pressurizing the gas chambers within an elastic membrane.

[0003] However, one problem faced by existing CMP equipment is the edge effect of the wafer. During the polishing process, the gas chambers located at the edge expand not only towards the wafer side but also towards the side away from the wafer. The pressure distribution of the gas chambers is uneven, resulting in poor polishing effect at the edge of the substrate.

[0004] The edge gas chamber expands not only towards the wafer side, but also towards the side away from the wafer. As the volume of the edge gas chamber increases, the pressure of the edge gas chamber on the edge substrate decreases, resulting in unevenness at the edge of the substrate. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of low polishing efficiency in the prior art, thereby providing a chemical mechanical polishing device.

[0006] This invention provides a chemical mechanical polishing apparatus, comprising:

[0007] The polishing head carrier has a groove at the bottom; the groove forms an installation space.

[0008] An elastic membrane structure is provided, with one side adapted to be disposed within the mounting space; the other side of the elastic membrane structure is adapted to be connected to a substrate; the elastic membrane structure is provided with a plurality of air chamber structures, and the gripping action of the substrate is achieved by adjusting the air pressure in the air chamber structures.

[0009] A pressure ring structure is provided between the air chamber and the polishing head carrier. The pressure ring structure includes a pressure ring body and an abutment portion disposed on the outer periphery of the pressure ring body. The abutment portion abuts against the air chamber structure and prevents the air chamber structure from expanding away from the substrate during expansion.

[0010] As a preferred embodiment, the elastic membrane structure is provided with a plurality of skirt structures, and an air chamber structure is formed between two adjacent skirt structures; the air chamber structure includes an edge air chamber and an inner air chamber; the edge air chamber is located at the edge of the elastic membrane structure; the inner air chamber is located inside the edge air chamber.

[0011] As a preferred embodiment, the abutting portion is an extension structure, which is disposed at one end of the pressure ring body near the air chamber structure; the extension structure extends away from the pressure ring body.

[0012] As a preferred embodiment, the cross-section of the extended structure is rectangular.

[0013] As a preferred embodiment, the cross-section of the extended structure is triangular.

[0014] As a preferred embodiment, the chemical mechanical polishing apparatus further includes:

[0015] A support assembly is connected to the air chamber structure; the support assembly is adapted to support the shape of the air chamber structure.

[0016] As a preferred embodiment, the chemical mechanical polishing apparatus further includes:

[0017] An elastic membrane carrier is adapted to be connected to the top of the inner air chamber; the elastic membrane carrier constrains the inner air chamber to deform in a direction away from the substrate.

[0018] As a preferred embodiment, the chemical mechanical polishing apparatus further includes:

[0019] An elastic membrane top cover is disposed between the elastic membrane carrier and the polishing head carrier.

[0020] As a preferred embodiment, the chemical mechanical polishing apparatus further includes:

[0021] A retaining ring is disposed at an extension structure at the bottom edge of the polishing head carrier; the retaining ring extends away from the polishing head carrier; the retaining ring is adapted to restrict the horizontal movement of the substrate.

[0022] As a preferred embodiment, the inner wall of the retaining ring contracts inward, and the inner wall of the retaining ring just contacts the substrate.

[0023] The technical solution of this invention has the following advantages:

[0024] 1. The present invention provides a chemical mechanical polishing apparatus, comprising a polishing head carrier, an elastic membrane structure, and a pressure ring structure. During the polishing process, the air pressure in the air chamber structure on the elastic membrane increases, and the air chamber structure applies a certain pressure to the substrate. At the same time, the abutting part on the pressure ring structure abuts against the air chamber structure and restricts the air chamber structure from expanding away from the substrate during the pressurization process. By setting the pressure ring structure, the expansion of the edge air chamber structure away from the substrate can be restricted, making the pressure distribution of the air chamber structure on the substrate more uniform and increasing the polishing effect of the substrate.

[0025] 2. The chemical mechanical polishing apparatus provided by the present invention, in order to limit the expansion volume of the gas chamber structure to the maximum extent, has an extension structure disposed at one end of the pressure ring body near the gas chamber structure; the extension structure extends away from the pressure ring body, wherein the cross-section of the extension structure is rectangular and can completely cover the gas chamber structure.

[0026] 3. The chemical mechanical polishing device provided by the present invention, in order to prevent polishing liquid from remaining on the extension structure and thus affecting the cleanliness of the pressure ring structure, sets the cross section of the extension structure as triangular. The triangular cross section of the extension structure facilitates the flow of polishing liquid along the inclined surface of the extension structure, thereby ensuring that no polishing liquid remains on the pressure ring structure.

[0027] 4. The chemical mechanical polishing device provided by the present invention is further provided with a support component, an elastic membrane carrier and an elastic membrane top plate, all of which restrict the elastic membrane structure and keep the elastic membrane structure in a stable state. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall structure of a chemical mechanical polishing device provided by the present invention.

[0030] Figure 2 The schematic diagram shows a triangular cross-section of the pressure ring structure of a chemical mechanical polishing device provided by the present invention.

[0031] Figure 3 This is a schematic diagram of the skirt structure of a chemical mechanical polishing device provided by the present invention.

[0032] Figure 4 This is a schematic diagram of the structure in the prior art.

[0033] Figure 5 This is a schematic diagram of the pressure ring structure of a chemical mechanical polishing device provided by the present invention.

[0034] Figure 6 This is a schematic diagram of a polishing head carrier for a chemical mechanical polishing device provided by the present invention.

[0035] Figure 7 This is a schematic diagram of the abutting portion on the pressure ring structure of a chemical mechanical polishing apparatus provided by the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Polishing head carrier; 11. Installation space; 2. Elastic membrane structure; 21. Air chamber structure; 211. Edge air chamber; 212. Inner air chamber; 22. Skirt structure; 221. Edge skirt; 2211. First skirt; 2212. Second skirt; 222. Inner skirt; 23. Surrounding structure; 3. Pressure ring structure; 31. Pressure ring body; 32. Abutting part; 4. Support assembly; 41. Inner support ring; 42. Outer support ring; 43. Inner ring; 44. Outer ring; 5. Elastic membrane carrier; 6. Elastic membrane top cover; 7. Retaining ring; 8. Substrate. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] like Figure 1 As shown, this embodiment provides a chemical mechanical polishing apparatus, including a polishing head carrier 1, an elastic membrane structure 2, and a pressure ring structure 3. The polishing head carrier 1 has a groove at its bottom, as shown... Figure 6As shown, the groove forms an installation space 11. One side of the elastic membrane structure 2 is adapted to be placed within the installation space 11, and the other side of the elastic membrane structure 2 is adapted to be connected to the substrate 8. Several air chamber structures 21 are provided on the elastic membrane structure 2. The gripping action of the substrate 8 is achieved by adjusting the air pressure in the air chamber structure 21. The pressure ring structure 3 is disposed between the air chamber structure 21 and the polishing head carrier 1. The pressure ring structure 3 includes a pressure ring body 31 and an abutment portion 32 disposed on the outer periphery of the pressure ring body 31. The abutment portion 32 abuts against the air chamber structure 21 and is adapted to prevent the air chamber structure 21 from expanding away from the substrate 8 during the expansion process. During the polishing process, the air pressure of the air chamber structure 21 on the elastic membrane increases, and the air chamber structure 21 applies a certain pressure to the substrate 8. At the same time, the abutting part 32 on the pressure ring structure 3 abuts against the air chamber structure 21 and restricts the expansion of the air chamber structure 21 away from the substrate 8 during the pressurization process, thus limiting the size of the expansion volume of the air chamber structure 21. By setting the pressure ring structure 3, the expansion of the edge air chamber structure 21 away from the substrate 8 can be restricted, making the pressure distribution of the air chamber structure 21 on the substrate 8 more uniform and increasing the polishing effect of the substrate 8.

[0043] It should be noted that during the gripping process, the polishing head carrier 1 is also connected to a transfer mechanism such as a robotic arm. The polishing head carrier 1 moves the elastic membrane structure 2 above the substrate 8 and brings the elastic membrane structure 2 into contact with the substrate 8. Negative pressure is introduced into the air chamber structure 21, which has a tendency to contract. Since the elastic membrane structure 2 is in contact with the substrate 8, the elastic membrane structure 2 has a certain adsorption force on the substrate 8. The substrate 8 is transferred to the polishing equipment by the adsorption force. Subsequently, positive pressure is introduced into the air chamber structure 21, which has a tendency to expand. The elastic membrane structure 2 applies a certain pressure to the substrate 8.

[0044] It should be noted that edge margin refers to a certain amount of space left by designers in the edge area of ​​a chip during the semiconductor manufacturing process to ensure chip quality and stability. This space can be used to accommodate errors during the manufacturing process.

[0045] It should be noted that substrate 8 refers to "a flat, rigid, and sturdy basic circular plate".

[0046] It should be noted that during the polishing process, polishing fluid needs to be added between the substrate 8 and the polishing equipment. The polishing fluid provides abrasive, softens the wafer, and assists in polishing.

[0047] Furthermore, the air chamber structure 21 includes an edge air chamber 211 and an inner air chamber 212. The edge air chamber 211 is located at the edge of the elastic membrane structure 2, and the inner air chamber 212 is located inside the edge air chamber 211.

[0048] It should be noted that the elastic membrane structure 2 is provided with several skirt structures 22, and an air chamber structure 21 is formed between two adjacent skirt structures 22. Specifically, the elastic membrane structure 2 is composed of skirt structures 22 and an elastic membrane located at the bottom of the skirt structures 22, and the skirt structures 22 and the elastic membrane are integrally formed. In this embodiment, the cavities separated by the skirt structures 22 all belong to the air chamber structure 21. Specifically, the skirt structure 22 includes an edge skirt 221 and an inner skirt 222. A surrounding structure 23 is provided on the edge of the elastic membrane structure 2 in a direction away from the substrate 8, wherein the edge skirt 221 is provided on the top of the surrounding structure 23. In this embodiment, the edge skirt 221 includes a first skirt 2211 and a second skirt 2212. The first skirt 2211 is "L"-shaped, one side wall of the first skirt 2211 is fixedly connected to the surrounding structure 23, and the other side wall of the first skirt 2211 is provided in the direction of the inner side of the elastic membrane structure 2. The second skirt edge 2212 is positioned towards the inside of the elastic membrane structure 2.

[0049] It should be noted that the elastic membrane at the bottom of the elastic membrane structure 2 is in direct contact with the substrate 8.

[0050] Specifically, the first skirt 2211 and the second skirt 2212 form an edge air chamber 211. During the process of introducing positive pressure into the edge air chamber 211, the other side wall of the first skirt 2211 undergoes major deformation, and the abutment portion 32 on the pressure ring structure 3 mainly abuts against the first side wall of the first skirt 2211. There are at least two inner skirts 222, which are in the shape of a "7" and are arranged opposite to each other.

[0051] In this embodiment, the inner skirt 222 has two pairs of opposing inner skirts 222 and one innermost inner skirt 222 facing outward; in this embodiment, the inner air chamber 212 has four chambers, which are formed by the cavity between every two inner skirts 222 in the direction from the inside out.

[0052] Furthermore, the abutment portion 32 is an extended structure. It should be noted that the extended structure can be positioned at any location on the outer periphery of the pressure ring body 31. To ensure the restraining effect of the abutment portion 32 on the edge air chamber 211, the extended structure is positioned at the end of the pressure ring body 31 near the air chamber structure 21. The extended structure extends away from the pressure ring body 31, such as... Figure 1 The extension structure extends to completely cover the edge air chamber 211. For example... Figure 7 As shown, the extension length of the extension structure can generally be controlled to 2 / 3 of the length of the edge air chamber 211, or it can be controlled to 1 / 2, 1 / 3, or other lengths of the edge air chamber 211.

[0053] In this embodiment, the abutting portion 32 of the pressure ring structure 3 directly abuts against the top of the first skirt 2211, increasing the downward pressure on the edge air chamber 211 by restricting the upward expansion of the first skirt 2211. It should be noted that, as... Figure 4 As shown, if the abutment part 32 is not provided, the expansion direction of the edge air chamber 211 is uncontrollable each time. Generally, the edge air chamber 211 will expand in the direction where it is not restrained. Figure 4 The upward expansion of the edge air chamber 211 leads to increased deformation, which, with prolonged and repeated use, affects its lifespan and slows down the reaction speed, thus impacting the polishing effect. This embodiment addresses this by limiting the additional expansion of the edge air chamber 211, thereby enabling a faster reaction and improving the polishing effect.

[0054] To further explain, reducing the deformation of the gas chamber increases its reaction rate: Without considering the coefficients of volume expansion and compressibility, according to the ideal gas law PV = NRT (where P is pressure, V is volume, N is amount of substance, R is the molar gas constant, and T is temperature), Among them, inflation speed If temperature T is a fixed value and R is a constant, then the right side of the formula is a constant. Therefore, when the expansion volume V decreases, the rate of pressure change is... Increased pressure means a faster response rate to reach the desired air pressure. At the same inflation pressure, a decrease in the expandable space of the air chamber increases the downward pressure exerted by the air chamber on the inner ring 43. The effect of the inflation pressure is twofold: one part is the force exerted by the air chamber on the surrounding space (the downward pressure exerted by the edge air chamber 211 on the substrate 8 originates from this), and the other part is the force used to counteract the elastic deformation caused by the expansion of the air chamber. According to the deformation formula of the elastic membrane: (Where ΔL is the length change of the elastic membrane after being subjected to an external force, L is the original length of the elastic membrane, F is the force of the elastic membrane expansion, A is the cross-sectional area of ​​the elastic membrane, and E is the elastic modulus.) The original length L and cross-sectional area A of the air chamber are fixed values, and the elastic modulus E is a constant. Therefore, the deformation ΔL of the air chamber is linearly related to the force F applied to the air chamber during inflation. The reduction in expansion space reduces the external force required for the air chamber to expand. Therefore, under the same inflation pressure, the force applied to the surrounding space will increase, and the downward pressure of the edge air chamber 211 on the substrate 8 will also increase. This achieves the effect of greater downward pressure under the same inflation pressure.

[0055] like Figure 5 As shown, in this embodiment, the cross-section of the extension structure is rectangular, and the specific extension structure is annular.

[0056] like Figure 2As shown, as an alternative implementation, the cross section of the extension structure can also be set as a triangle, specifically a frustum shape. In order to prevent polishing liquid from remaining on the extension structure and thus affecting the cleanliness of the pressure ring structure 3, the triangular cross section of the extension structure facilitates the flow of polishing liquid along the inclined surface of the extension structure, thereby ensuring that no polishing liquid remains on the pressure ring structure 3.

[0057] Furthermore, this embodiment also includes a support component 4, which is connected to the air chamber structure 21 and is adapted to support the shape of the air chamber structure 21.

[0058] The specific support component 4 includes an inner support ring 41, an outer support ring 42, an inner ring 43, and an outer ring 44.

[0059] The inner support ring 41 and the outer support ring 42 are respectively disposed between two oppositely disposed inner skirts 222. The inner support ring 41 and the outer support ring 42 form two inner air chambers 212 with the two oppositely disposed inner skirts 222. The inner support ring 41 and the outer support ring 42 are circular rings with a "T" shaped cross section. The horizontal sidewalls of the inner support ring 41 and the outer support ring 42 abut against the inner top of the inner skirt 222. The vertical sidewalls of the inner support ring 41 and the outer support ring 42 are fixedly connected to the polishing head carrier 1. It should be noted that the end of each skirt structure 22 is constrained by the inner support ring 41 and the outer support ring 42 and the elastic membrane carrier 5. By constraining the end of the skirt structure 22, the skirt structure 22 as a whole will not move during operation.

[0060] like Figure 3 As shown, an annular groove is provided on the outer periphery of the edge structure 23, and the outer ring 44 is completely set within the annular groove, providing support for the edge structure 23. The top and bottom of the inner ring 43 are respectively engaged with the inner side of the edge structure 23, also providing support for the edge structure 23. It should be noted that during operation, the edge air chamber 211 expands, applying a certain pressure to the outer ring 44 below. The outer ring 44 and inner ring 43 then transmit the pressure downwards, providing edge pressure to the substrate 8 through the elastic membrane structure 2. In this design, the outer ring 44 and inner ring 43 serve to transmit pressure.

[0061] Furthermore, the chemical mechanical polishing apparatus also includes an elastic membrane carrier 5, which is connected to the top of the inner gas chamber 212. The elastic membrane carrier 5 abuts against the tops of two opposing inner skirts 222. The elastic membrane carrier 5 can constrain the deformation of the inner gas chamber 212 in a direction away from the substrate 8. The elastic membrane carrier 5 is fixedly connected to the inner support ring 41 and the outer support ring 42 by adhesive bonding or screws. The elastic membrane carrier 5 provides support for the inner support ring 41 and the outer support ring 42. In this embodiment, the elastic membrane carrier 5 is also annular.

[0062] Furthermore, an elastic membrane top cover 6 is provided, which is disposed between the elastic membrane carrier 5 and the polishing head carrier 1. The elastic membrane top cover 6 is suitable for accommodating the elastic membrane carrier 5 in the middle, and the two sides of the elastic membrane top cover 6 extend towards the substrate 8, respectively abutting the end of the second skirt 2212 and the end of the innermost skirt 222 facing outward. By providing the elastic membrane top cover 6, the shape of the inner air chamber 212 and the edge air chamber 211 is further restricted to prevent deformation during polishing. Specifically, the elastic membrane top cover 6 is fixedly connected to the polishing head carrier 1 and the elastic membrane carrier 5 by means of adhesive or screws. It should be noted that the inner support ring 41 and the outer support ring 42, as well as the elastic membrane carrier 5 and the elastic membrane top cover 6 and the skirt structure 22, enclose the cavity between the skirt structure 22 to form a sealed air chamber structure 21. It should be noted that the elastic membrane top cover 6, together with the second skirt 2212 and the first skirt 2211, forms a sealed space, which is the edge air chamber 211.

[0063] Furthermore, a retaining ring 7 is provided, which is located at the extension structure at the bottom edge of the polishing head carrier 1. The retaining ring 7 extends away from the polishing head carrier 1 and is adapted to restrict the horizontal movement of the substrate 8. Specifically, the inner wall of the retaining ring 7 tapers inward, and the inner wall of the retaining ring 7 just contacts the substrate 8. The retaining ring 7 is engaged with the outer periphery of the substrate 8, and the retaining ring 7 prevents the position of the substrate 8 from changing during the polishing process. Specifically, the retaining ring 7 is fixedly connected to the polishing head carrier 1 by means of adhesive or screws.

[0064] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A chemical mechanical polishing apparatus characterized by comprising: The polishing head carrier (1) is provided with a groove in the bottom; the groove forms a mounting space (11); The elastic film structure (2) is suitable to be arranged in the mounting space (11) on one side; the other side of the elastic film structure (2) is suitable to be connected with the substrate (8); a plurality of air chamber structures (21) are arranged on the elastic film structure (2); the polishing action on the substrate (8) is realized by adjusting the air pressure in the air chamber structure (21); The pressure ring structure (3) is arranged between the air chamber and the polishing head carrier (1); the pressure ring structure (3) comprises a pressure ring body (31) and an abutting portion (32) arranged on the outer periphery of the pressure ring body (31); the abutting portion (32) abuts against the air chamber structure (21); the abutting portion (32) prevents the air chamber structure (21) from expanding in the direction away from the substrate (8) during the expansion process; A plurality of skirt structures (22) are arranged on the elastic film structure (2); the air chamber structure (21) is surrounded by two adjacent skirt structures (22); the air chamber structure (21) comprises an edge air chamber (211) and an inner side air chamber (212); the edge air chamber (211) is located at the edge of the elastic film structure (2); the inner side air chamber (212) is located at the inner side of the edge air chamber (211); a surrounding edge structure (23) is arranged at the edge of the elastic film structure (2) in the direction away from the substrate (8); The abutting portion (32) is an extension structure; the extension structure is arranged at one end of the pressure ring body (31) close to the air chamber structure (21); the extension structure is arranged in the direction away from the pressure ring body (31); The skirt structure (22) comprises an edge skirt (221); the edge skirt (221) is arranged at the top of the surrounding edge structure (23); the edge skirt (221) comprises a first skirt (2211) and a second skirt (2212); one side wall of the first skirt (2211) is fixedly connected with the surrounding edge structure (23); the first skirt (2211) and the second skirt (2212) surround the edge air chamber (211); the abutting portion (32) mainly abuts against the first side wall of the first skirt (2211). The cross section of the extension structure is rectangular.

2. The chemical mechanical polishing apparatus of claim 1, wherein The cross section of the extension structure is triangular.

3. The chemical mechanical polishing apparatus of claim 1, wherein The chemical mechanical polishing device further comprises:

4. The chemical mechanical polishing apparatus of claim 1, wherein A support assembly (4) connected with the air chamber structure (21); the support assembly (4) is suitable to support the shape of the air chamber structure (21). The chemical mechanical polishing device further comprises:

5. The chemical mechanical polishing apparatus of claim 1, wherein An elastic film carrier (5) suitable to be connected with the top of the inner side air chamber (212); the elastic film carrier (5) restricts the deformation of the inner side air chamber (212) in the direction away from the substrate (8). The chemical mechanical polishing device further comprises:

6. The chemical mechanical polishing apparatus of claim 5, wherein An elastic film top cover (6) arranged between the elastic film carrier (5) and the polishing head carrier (1). The chemical mechanical polishing device further comprises:

7. The chemical mechanical polishing apparatus of claim 6, wherein ​ A holding ring (7) is arranged at the extension structure of the bottom edge of the polishing head carrier (1); the holding ring (7) is arranged extending towards the direction away from the polishing head carrier (1); the holding ring (7) is adapted to limit the movement of the substrate (8) in the horizontal direction.

8. The chemical mechanical polishing apparatus of claim 7, wherein The inner wall of the holding ring (7) is contracted towards the inside, and the inner wall of the holding ring (7) just contacts the substrate (8).

Images