Polishing apparatus and polishing method

Abstract

The invention provides a polishing apparatus and a polishing method. The polishing equipment comprises a platform, a polishing pad and a polishing head, the polishing pad is laid on the surface of the platform, the polishing head is in contact with the polishing pad, a polished wafer is arranged between the polishing head and the polishing pad, and a hard film with a concave center is further arranged between the polished wafer and the polishing head. The shape of the hard film is changed, and the shape design that the center thickness is smaller than the edge thickness is adopted, so that the removal amount is distributed more uniformly in the polishing process, and the flatness of the surface of the wafer is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor equipment, and in particular to a polishing device and a polishing method. Background Art

[0002] Chemical mechanical grinding, also known as chemical mechanical polishing, is a processing technology that combines chemical corrosion and mechanical removal. It is a technology in semiconductor processing technology that can achieve global surface flattening.

[0003] Chemical mechanical polishing technology combines the advantages of chemical polishing and mechanical polishing. Pure chemical polishing has high surface accuracy, low damage, good integrity, and is not prone to surface / subsurface damage, but the polishing rate is slow, the material removal efficiency is low, the surface profile accuracy cannot be corrected, and the polishing consistency is relatively poor; pure mechanical polishing has good polishing consistency, high surface flatness, and high polishing efficiency, but it is prone to surface layer / subsurface layer damage and the surface roughness value is relatively low. Chemical mechanical polishing absorbs the advantages of both, and can obtain a more perfect surface while ensuring material removal efficiency. The flatness obtained is 1-2 orders of magnitude higher than that of using these two types of polishing alone, and can achieve surface roughness from nanometer level to atomic level.

[0004] Therefore, in the polishing process, how to ensure the flatness of the polished wafer is obviously a problem that needs to be solved in the prior art. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a polishing device and a polishing method, which can improve the flatness of a polished wafer.

[0006] In order to solve the above problems, the present invention provides a polishing device, including a platform, a polishing pad and a polishing head, the polishing pad is laid on the surface of the platform, the polishing head is in contact with the polishing pad, the wafer to be polished is placed between the polishing head and the polishing pad, and a hard film with a central concave shape is also included between the polished wafer and the polishing head.

[0007] Optionally, the material of the hard film is stainless steel.

[0008] Optionally, the hard film is a continuous thin film, and the center thickness is smaller than the edge thickness.

[0009] Optionally, the hard film is formed by splicing a plurality of concentric rings, and the thickness of the concentric rings close to the center is smaller than the thickness at the edge.

[0010] Optionally, a retaining ring is fastened to the periphery of the polished wafer, and the hard film is placed inside the retaining ring.

[0011] In order to solve the above problems, the present invention provides a polishing method, comprising: polishing a wafer and setting a hard film with a central concave shape between the polished wafer and the polishing head; detecting the thickness difference between the center and edge of the polished wafer; and adjusting the degree of the central concave of the hard film according to the detection result.

[0012] Optionally, the material of the hard film is stainless steel.

[0013] Optionally, the hard film is a continuous thin film, and the center thickness is smaller than the edge thickness.

[0014] Optionally, the hard film is formed by splicing a plurality of concentric rings, and the thickness of the concentric rings close to the center is smaller than the thickness at the edge.

[0015] The present invention changes the shape of the hard film and adopts a shape design in which the center thickness is smaller than the edge thickness, so that the removal amount is more evenly distributed during the polishing process, thereby improving the flatness of the wafer surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attached Figure 1 Shown is a schematic structural diagram of a polishing device according to a specific embodiment of the present invention.

[0017] Attached Figure 2 Shown is a schematic structural diagram of a polishing device according to a specific embodiment of the present invention.

[0018] Attached Figure 3 Shown is a schematic structural diagram of a polishing method according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0019] The specific implementation modes of the polishing equipment and the polishing method provided by the present invention are described in detail below with reference to the accompanying drawings.

[0020] Attached Figure 1 The figure is a schematic structural diagram of a polishing device according to a specific embodiment of the present invention, comprising a platform 10, a polishing pad 11 and a polishing head 12, wherein a wafer 14 to be polished is placed between the polishing head 12 and the polishing pad 11. The wafer 14 may be a wafer of any common semiconductor material including silicon, germanium, silicon carbide, GaAs, and GaN.

[0021] A hard film 13 with a concave center is also included between the polished wafer 14 and the polishing head 12. A retaining ring 15 is fastened to the periphery of the polished wafer 14, and the hard film 13 is placed in the retaining ring 15. The material of the hard film is preferably stainless steel, and can also be other materials such as polytetrafluoroethylene, polyurethane, etc.

[0022] In this specific embodiment, the polishing pad 11 is laid on the surface of the platform 10, and the polishing head 12 contacts the polishing pad 11 and applies a certain pressure to polish the wafer 14. It is found in the experiment that during the polishing process of the wafer 14, the linear speed at the edge of the wafer is greater than that at the center, resulting in a greater amount of removal at the periphery than at the center. The current common method is to use a retaining ring 15 to protect the periphery of the wafer 14, but this will cause the amount of removal at the periphery to be lower than that at the center. Therefore, this specific embodiment changes the shape of the hard film 13, and the hard film 13 is a continuous thin film with a center thickness less than an edge thickness, so that the removal amount is more evenly distributed during the polishing process, thereby improving the flatness of the surface of the wafer 14.

[0023] Attached Figure 2 The figure shows a schematic diagram of the structure of the polishing equipment according to another specific embodiment of the present invention, which includes a platform 10, a polishing pad 11 and a polishing head 12, and the wafer 14 to be polished is placed between the polishing head 12 and the polishing pad 11. A hard film 23 with a central concave shape is also included between the polished wafer 14 and the polishing head 12. A retaining ring 15 is fastened to the periphery of the polished wafer 14, and the hard film 23 is placed in the retaining ring 15. The material of the hard film is. In this specific embodiment, the hard film 23 is composed of a plurality of concentric rings, and the thickness of the concentric rings close to the center is less than the thickness of the edge, so that the center thickness is less than the edge thickness, so that the removal amount is more evenly distributed during the polishing process, thereby improving the flatness of the surface of the wafer 14.

[0024] Attached Figure 3 The figure is a schematic diagram of the implementation steps of the polishing method according to a specific embodiment of the present invention, including: step S10, polishing a wafer, and setting a hard film with a central concave shape between the polished wafer and the polishing head; step S11, detecting the difference in thickness between the center and edge of the polished wafer; step S12, adjusting the degree of the central concave of the hard film according to the detection result.

[0025] In step S10, the wafer may be a wafer made of any common semiconductor material such as silicon, germanium, silicon carbide, GaAs, and GaN.

[0026] Although a hard film with a concave center shape is used in step S10 to adjust the thickness difference of the wafer, it cannot be guaranteed that the shape of the hard film can compensate for the process deviation, which may lead to over-compensation or under-compensation. Therefore, the subsequent steps S11 and S12 should be implemented to adjust the compensation degree of the hard film to obtain a flat wafer.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A polishing device, comprising a platform, a polishing pad and a polishing head, wherein the polishing pad is laid on the surface of the platform, the polishing head is in contact with the polishing pad, and a wafer to be polished is placed between the polishing head and the polishing pad, characterized in that: A hard film with a central concave shape is also included between the polished wafer and the polishing head.

2. The polishing device according to claim 1, characterized in that: The material of the hard film is stainless steel.

3. The polishing device according to claim 1, characterized in that: The hard film is a continuous thin film, and the thickness at the center is smaller than the thickness at the edge.

4. The polishing device according to claim 1, characterized in that: The hard film is formed by splicing a plurality of concentric rings, and the thickness of the concentric rings close to the center is less than the thickness at the edge.

5. The polishing device according to claim 1, characterized in that: A retaining ring is fastened to the periphery of the polished wafer, and the hard film is placed inside the retaining ring.

6. A polishing method, characterized in that: include: Polishing a wafer and providing a hard film with a central concave shape between the polished wafer and the polishing head; Detect the difference in thickness between the center and edge of the polished wafer; The degree of the center depression of the hard film is adjusted according to the test results.

7. The polishing method according to claim 6, characterized in that: The material of the hard film is stainless steel.

8. The polishing method according to claim 6, characterized in that: The hard film is a continuous thin film, and the thickness at the center is smaller than the thickness at the edge.

9. The polishing method according to claim 6, characterized in that: The hard film is formed by splicing a plurality of concentric rings, and the thickness of the concentric rings close to the center is less than the thickness at the edge.

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