Polishing head and polishing equipment for square silicon wafer

Abstract

The polishing head comprises a shell, a carrier, a retaining ring and an elastic film assembly, the shell is used for being connected to the lower portion of a rotary driving part, the carrier is connected to the lower portion of the shell and provided with a containing cavity with a downward opening, the retaining ring is connected to the lower end face of the carrier, and the elastic film assembly is connected to the lower end face of the carrier. The elastic membrane assembly is arranged in the containing cavity, a buffering cushion ring is arranged at the bottom of the elastic membrane assembly, and the buffering cushion ring is arranged close to the outer ring of the elastic membrane assembly. According to the polishing head for the square silicon wafer, the incircle area of the square silicon wafer is ground through the middle area of the elastic film assembly, meanwhile, the buffering cushion ring close to the outer ring of the elastic film assembly abuts against the upper portion of the corner area of the square silicon wafer, effective buffering on the corner area is formed, and the polishing effect is improved. The problem that stress concentration is generated in the corner area in the grinding process is avoided, the grinding structure of the corner area is optimized, synchronous grinding of the inscribed circle area and the corner area is achieved, and the grinding quality of the square silicon wafer is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of square silicon wafer polishing, and more specifically, relates to a polishing head and polishing equipment for square silicon wafers. Background Art

[0002] Chemical mechanical polishing (CMP) is a global flattening ultra-precision surface processing technology that combines chemical reaction and mechanical friction. The chemical substances in the CMP liquid solution react with the material on the surface to be polished to form a layer of oxide or nitrate film that can be grinded. Subsequently, the high parts of the polished surface are cut or flattened by mechanical friction using a rotating polishing disc and abrasives to make the surface smoother.

[0003] At present, in order to improve production efficiency, the method of increasing the wafer area is often used. When the area of ​​the chip to be processed is certain, using a larger wafer can effectively improve the wafer utilization rate. For example, when producing chips of the same size on a 12-inch wafer and an 8-inch wafer, the number of wafers available on a 12-inch wafer is more than 50% more than that on an 8-inch wafer. In the above method, although a larger wafer area can improve the utilization rate of the wafer to a certain extent, it still cannot solve the problem of low edge utilization at the root.

[0004] Therefore, a method of using square silicon wafers to produce chips has emerged. This method produces a large number of chips, which can effectively save wasted area, improve the utilization rate of silicon wafers, and at the same time improve production efficiency and reduce the cost of a single chip. However, due to the sharp corners of square silicon wafers, edge stress is easily generated during the chemical grinding process, which can easily cause wafer damage and affect the overall yield of the product. Summary of the invention

[0005] The object of the present invention is to provide a polishing head and a polishing device for square silicon wafers, which can effectively avoid stress concentration during the processing of square silicon wafers and improve the processing efficiency of square silicon wafers.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a polishing head for square silicon wafers, including a shell, a carrier, a retaining ring and an elastic membrane assembly, the shell is used to be connected to the bottom of a rotating driving member, the carrier is connected to the bottom of the shell, the carrier has a accommodating cavity opening downward, the retaining ring is connected to the lower end surface of the carrier, the elastic membrane assembly is arranged in the accommodating cavity, and a buffer gasket ring is provided at the bottom of the elastic membrane assembly, the buffer gasket ring is arranged close to the outer ring of the elastic membrane assembly, and is used to press against the top surface of the corner area of ​​the square silicon wafer.

[0007] In one possible implementation, the elastic membrane assembly has a central chamber and a peripheral chamber. The peripheral chamber is located on the periphery of the central chamber and is used to adsorb or press the corner area of ​​the square silicon wafer. The central chamber is used to adsorb or press the inscribed circular area of ​​the square silicon wafer. The buffer ring is arranged correspondingly to the peripheral chamber above and below.

[0008] In some embodiments, during the polishing process of the square silicon wafer, the pressure of the central chamber on the inscribed circular area of ​​the square silicon wafer is greater than the pressure of the peripheral chamber on the corner area of ​​the square silicon wafer.

[0009] In a possible implementation, the central chamber includes a first chamber and a second chamber, the second chamber is located at the periphery of the first chamber, and both the first chamber and the second chamber are used to absorb or press the inscribed circular area of ​​the square silicon wafer.

[0010] In some embodiments, during the polishing process of the square silicon wafer, the pressure of the first chamber on the square silicon wafer is equal to the pressure of the second chamber on the square silicon wafer.

[0011] In one possible implementation, the peripheral chamber includes a third chamber and a fourth chamber, the third chamber is located at the periphery of the second chamber, and the fourth chamber is located at the periphery of the third chamber, and both the third chamber and the fourth chamber are used to adsorb or press the corner area of ​​the square silicon wafer.

[0012] In some embodiments, during the polishing process of the square silicon wafer, the pressure of the third chamber on the square silicon wafer is greater than the pressure of the fourth chamber on the square silicon wafer.

[0013] In a possible implementation, a plurality of adsorption holes are provided through the buffer gasket ring, and the plurality of adsorption holes are arranged at intervals along the circumference of the buffer gasket ring and are arranged close to the inner ring of the buffer gasket ring.

[0014] In a possible implementation, the thickness of the buffer ring gradually increases from the inner ring to the outer ring.

[0015] Compared with the prior art, the solution shown in the embodiment of the present application utilizes the middle area of ​​the elastic membrane assembly to grind the inscribed circle area of ​​the square silicon wafer, and at the same time utilizes the buffer ring close to the outer ring of the elastic membrane assembly to press against the corner area of ​​the square silicon wafer, thereby forming an effective buffer for the corner area, avoiding the problem of stress concentration in the corner area during the grinding process, optimizing the grinding structure of the corner area, realizing the synchronous grinding of the inscribed circle area and the corner area, ensuring the grinding quality of the square silicon wafer, and improving the production efficiency of the chip.

[0016] The present invention also provides a square silicon wafer polishing device, which includes a polishing head for a square silicon wafer. The square silicon wafer polishing device uses the middle area of ​​the elastic membrane assembly to grind the inscribed circle area of ​​the square silicon wafer, and uses the buffer ring close to the outer ring of the elastic membrane assembly to press against the corner area of ​​the square silicon wafer to form an effective buffer for the corner area, avoid the problem of stress concentration in the corner area during the grinding process, optimize the grinding structure of the corner area, realize the synchronous grinding of the inscribed circle area and the corner area, ensure the grinding quality of the square silicon wafer, and improve the production efficiency of the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 A schematic diagram of the front cross-sectional structure of a polishing head for square silicon wafers provided by an embodiment of the present invention in use; Figure 2 For the embodiment of the present invention Figure 1 The partially enlarged structural diagram of middle Ⅰ; Figure 3 For the embodiment of the present invention Figure 1 A schematic diagram of the structure of a polishing head for square silicon wafers in a bottom-up view in use; Figure 4 For the embodiment of the present invention Figure 3 A schematic diagram of the relative position structure of the square silicon wafer and the first chamber, the second chamber, the third chamber and the fourth chamber; Figure 5 For the embodiment of the present invention Figure 1 A schematic diagram of the structure of the middle buffer ring when viewed from above; Figure 6 It is a schematic diagram of the structure of a square silicon wafer applicable to an embodiment of the present invention.

[0019] Among them, the reference numerals in the figure are: 1. Shell; 2. Carrier; 21. Accommodating cavity; 3. Retaining ring; 4. Elastic membrane assembly; 5. Buffer ring; 51. Adsorption hole; 6. Central chamber; 61. First chamber; 62. Second chamber; 7. Peripheral chamber; 71. Third chamber; 72. Fourth chamber; 8. Square silicon wafer; 81. Inscribed circle area; 82. Corner area. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on another element or indirectly on another element. It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "back", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0022] Please also read Figures 1 to 5 , the polishing head and polishing equipment for square silicon wafers provided by the present invention are now described. The polishing head for square silicon wafers includes a shell 1, a carrier 2, a retaining ring 3 and an elastic membrane assembly 4, the shell 1 is used to be connected to the bottom of the rotating driving member, the carrier 2 is connected to the bottom of the shell 1, the carrier 2 has a receiving cavity 21 with an opening facing downward, the retaining ring 3 is connected to the lower end surface of the carrier 2, the elastic membrane assembly 4 is arranged in the receiving cavity 21, and a buffer ring 5 is provided at the bottom of the elastic membrane assembly 4, and the buffer ring 5 is arranged close to the outer ring of the elastic membrane assembly 4, and is used to press against the top surface of the corner area 82 of the square silicon wafer 8.

[0023] Compared with the prior art, the polishing head for square silicon wafers provided in the present embodiment utilizes the middle area of ​​the elastic membrane assembly 4 to grind the inscribed circular area 81 of the square silicon wafer 8, and at the same time utilizes the buffer pad ring 5 close to the outer ring of the elastic membrane assembly 4 to press against the corner area 82 of the square silicon wafer 8, thereby forming an effective buffer for the corner area 82, avoiding the problem of stress concentration in the corner area 82 during the grinding process, optimizing the grinding structure of the corner area 82, realizing the synchronous grinding of the inscribed circular area 81 and the corner area 82, ensuring the grinding quality of the square silicon wafer 8, and improving the production efficiency of the chip.

[0024] In this embodiment, when the square silicon wafer 8 is adsorbed by the polishing head for grinding, it can be divided into an inscribed circle area 81 near the center and a corner area 82 near the corner according to the different stress conditions of each area of ​​the square silicon wafer 8. Specifically, the inscribed circle area 81 is formed by drawing an inscribed circle on the square silicon wafer 8, and the area inside the inscribed circle is the inscribed circle area 81, and the other areas outside the inscribed circle are defined as the corner area 82.

[0025] The inscribed circle area 81 and the corner area 82 are subjected to different forces during the grinding process. The inscribed circle area 81 is continuous in the circumferential direction and is subjected to relatively uniform forces during the grinding process. The corner area 82 is not continuous in the circumferential direction and is subjected to uneven forces at certain positions in the corner area 82 during the grinding process, which easily leads to stress concentration problems at the corner points.

[0026] When polishing the square silicon wafer 8 , the square silicon wafer 8 is adsorbed under the elastic membrane assembly 4 , the top surface of the inscribed circular area 81 directly contacts the elastic membrane assembly 4 , and the top surface of the corner area 82 of the square silicon wafer 8 effectively contacts the bottom surface of the buffer ring 5 .

[0027] During grinding, when the polishing head drives the square silicon wafer 8 to move down and press against the polishing pad, the polishing head and the polishing pad rotate in the same direction, and the polishing liquid is supplied between the polishing pad and the square silicon wafer 8. The buffer pad ring 5 can effectively alleviate the pressure on the corner area 82, avoid stress concentration in the corner area 82, and cause poor processing or damage, so that different areas of the entire square silicon wafer 8 are subjected to different pressures, which meets the effect of synchronous grinding processing in different areas, ensures the molding quality of the square silicon wafer 8, meets the effective cutting of subsequent chips, and improves the overall utilization rate of the square silicon wafer 8.

[0028] In one possible implementation, see Figures 1 to 5 The elastic membrane assembly 4 has a central chamber 6 and a peripheral chamber 7. The peripheral chamber 7 is located on the periphery of the central chamber 6 and is used to adsorb or press the corner area 82 of the square silicon wafer 8. The central chamber 6 is used to adsorb or press the inscribed circular area 81 of the square silicon wafer 8. The buffer ring 5 and the peripheral chamber 7 are arranged correspondingly up and down.

[0029] In this embodiment, the elastic membrane assembly 4 is in the form of a combination of a central chamber 6 and a peripheral chamber 7, wherein the central chamber 6 corresponds to the inscribed circular area 81 of the square silicon wafer 8, and the peripheral chamber 7 corresponds to the corner area 82 of the square silicon wafer 8. By applying different pressures to the central chamber 6 and the peripheral chamber 7, pressure control at different positions of the inscribed circular area 81 and the corner area 82 of the square silicon wafer 8 is achieved, and by providing the buffer ring 5 and applying pressure in different areas, effective protection of the corner area 82 is achieved, thereby avoiding the problem of stress concentration and achieving a good grinding effect.

[0030] For some examples, see Figures 1 to 5 During the polishing process of the square silicon wafer 8 , the pressure of the central chamber 6 on the inscribed circular area 81 of the square silicon wafer 8 is greater than the pressure of the peripheral chamber 7 on the corner area 82 of the square silicon wafer 8 .

[0031] In the present embodiment, by controlling the pressure of the central chamber 6 to be greater than the pressure of the peripheral chamber 7, the pressure applied to the inscribed circular area 81 of the square silicon wafer 8 is greater than the pressure applied to the corner area 82. The inscribed circular area 81 is able to withstand a larger pressure, while the corner area 82 on the periphery is subjected to a smaller pressure, thereby forming special protection for the corner area 82, avoiding stress concentration, and achieving synchronous grinding of different areas of the square silicon wafer 8.

[0032] In one possible implementation, see Figures 1 to 5 The central chamber 6 includes a first chamber 61 and a second chamber 62 . The second chamber 62 is located at the periphery of the first chamber 61 . The first chamber 61 and the second chamber 62 are both used to absorb or press the inscribed circular area 81 of the square silicon wafer 8 .

[0033] In this embodiment, the central chamber 6 is a combination of a first chamber 61 and a second chamber 62. The first chamber 61 can correspond to the center position of the inscribed circular area 81, and the second chamber 62 can correspond to the position of the inscribed circular area 81 close to the outer circle, so as to realize the zoned pressure control of different positions of the inscribed circular area 81.

[0034] During the polishing process of the square silicon wafer 8, the pressure of the first chamber 61 on the square silicon wafer 8 is equal to the pressure of the second chamber 62 on the square silicon wafer 8. The first chamber 61 and the second chamber 62 are used to apply pressure to different positions of the inscribed circle area 81 respectively. Since the areas where the square silicon wafer 8 contacts the first chamber 61 and the second chamber 62 are both the inscribed circle area 81, that is, the area within the inscribed circle of the square silicon wafer 8, this area does not involve corner problems. Therefore, the first chamber 61 and the second chamber 62 can use the same pressure to act on the inscribed circle area 81, which helps to improve grinding efficiency, ensure grinding quality, and improve grinding accuracy.

[0035] In one possible implementation, see Figures 1 to 5 The peripheral chamber 7 includes a third chamber 71 and a fourth chamber 72. The third chamber 71 is located at the periphery of the second chamber 62, and the fourth chamber 72 is located at the periphery of the third chamber 71. The third chamber 71 and the fourth chamber 72 are both used to absorb or press the corner area 82 of the square silicon wafer 8.

[0036] In this embodiment, the arrangement of the third chamber 71 and the fourth chamber 72 is similar to that of the first chamber 61 and the second chamber 62. The peripheral chamber 7 is divided into the third chamber 71 and the fourth chamber 72. The third chamber 71 can correspond to the center position of the corner area 82, and the fourth chamber 72 can correspond to the position of the corner area 82 close to the corner point, thereby realizing zoned pressure control of different positions of the corner area 82.

[0037] Specifically, during the polishing process of the square silicon wafer 8, the pressure of the third chamber 71 on the square silicon wafer 8 is greater than the pressure of the fourth chamber 72 on the square silicon wafer 8. Since the position of the corner area 82 close to the corner point is most likely to have stress concentration, it is necessary to further reduce the pressure at this position to form a good protective effect. The pressure of the third chamber 71 should be less than the pressure of the second chamber 62, and the pressure of the third chamber 71 is greater than the pressure of the fourth chamber 72 at the same time, forming a trend of gradually decreasing pressure from the center to the corner of the square silicon wafer 8, avoiding stress concentration at the corner point, ensuring the effective removal of materials in different areas of the square silicon wafer 8, and forming a good grinding effect.

[0038] In one possible implementation, see Figures 1 to 5 The buffer ring 5 is provided with a plurality of adsorption holes 51 , which are arranged at intervals along the circumference of the buffer ring 5 and are arranged close to the inner circle of the buffer ring 5 .

[0039] In this embodiment, a plurality of adsorption holes 51 are provided on the buffer ring 5, and the adsorption holes 51 connect the upper and lower sides of the buffer ring 5 to each other, thereby meeting the adsorption requirements of the elastic membrane assembly 4 on the corner area 82 of the square silicon wafer 8, and ensuring the effective adsorption and rotation driving effect of the polishing head on various areas of the square silicon wafer 8.

[0040] Specifically, the adsorption holes 51 are arranged close to the inner circle of the buffer ring 5 so that they can correspond to the larger area of ​​the corner region 82 and meet the adsorption performance requirements of the corner region 82 .

[0041] In one possible implementation, see Figures 1 to 5 The thickness of the buffer ring 5 gradually increases from the inner circle to the outer circle. The thickness of the buffer ring 5 is greater near the outer circle. The thicker the buffer ring 5 is, the more obvious the buffering effect is, which is convenient for more targeted reduction of stress concentration in the corner area 82 of the square silicon wafer 8, forming buffer protection for different positions of the corner area 82, and ensuring the grinding quality of the position.

[0042] Based on the same inventive concept, the embodiment of the present application also provides a square silicon wafer polishing device, which includes a polishing head for a square silicon wafer. The square silicon wafer polishing device uses the middle area of ​​the elastic membrane assembly 4 to grind the inscribed circular area 81 of the square silicon wafer 8, and at the same time uses the buffer ring 5 close to the outer ring of the elastic membrane assembly 4 to press against the corner area 82 of the square silicon wafer 8, forming an effective buffer for the corner area 82, avoiding the problem of stress concentration in the corner area 82 during the grinding process, optimizing the grinding structure of the corner area 82, realizing the synchronous grinding of the inscribed circular area 81 and the corner area 82, ensuring the grinding quality of the square silicon wafer 8, and improving the production efficiency of the chip.

[0043] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polishing head for square silicon wafers, characterized in that: The invention comprises a shell (1), a carrier (2), a retaining ring (3) and an elastic membrane assembly (4), wherein the shell (1) is used to be connected to the bottom of a rotating driving member, the carrier (2) is connected to the bottom of the shell (1), the carrier (2) has a accommodating cavity (21) opening downward, the retaining ring (3) is connected to the lower end surface of the carrier (2), the elastic membrane assembly (4) is arranged in the accommodating cavity (21), and a buffer ring (5) is provided at the bottom of the elastic membrane assembly (4), and the buffer ring (5) is arranged close to the outer ring of the elastic membrane assembly (4) and is used to press against the top surface of the corner area (82) of the square silicon wafer (8).

2. The polishing head for square silicon wafers according to claim 1, characterized in that: The elastic membrane assembly (4) has a central chamber (6) and a peripheral chamber (7); the peripheral chamber (7) is located on the periphery of the central chamber (6) and is used to absorb or press the corner area (82) of the square silicon wafer (8); the central chamber (6) is used to absorb or press the inscribed circle area (81) of the square silicon wafer (8); and the buffer ring (5) is arranged correspondingly to the peripheral chamber (7) above and below.

3. The polishing head for square silicon wafers according to claim 2, characterized in that: During the polishing process of the square silicon wafer (8), the pressure exerted by the central chamber (6) on the inscribed circular area (81) of the square silicon wafer (8) is greater than the pressure exerted by the peripheral chamber (7) on the corner area (82) of the square silicon wafer (8).

4. The polishing head for square silicon wafers according to claim 2, characterized in that: The central chamber (6) comprises a first chamber (61) and a second chamber (62), wherein the second chamber (62) is located at the periphery of the first chamber (61), and the first chamber (61) and the second chamber (62) are both used to absorb or press the inscribed circular area (81) of the square silicon wafer (8).

5. The polishing head for square silicon wafers according to claim 4, characterized in that: During the polishing process of the square silicon wafer (8), the pressure of the first chamber (61) on the square silicon wafer (8) is equal to the pressure of the second chamber (62) on the square silicon wafer (8).

6. The polishing head for square silicon wafers according to claim 4, characterized in that: The peripheral chamber (7) comprises a third chamber (71) and a fourth chamber (72), wherein the third chamber (71) is located at the periphery of the second chamber (62), and the fourth chamber (72) is located at the periphery of the third chamber (71), and both the third chamber (71) and the fourth chamber (72) are used to absorb or press the corner area (82) of the square silicon wafer (8).

7. The polishing head for square silicon wafers according to claim 6, characterized in that: During the polishing process of the square silicon wafer (8), the pressure exerted by the third chamber (71) on the square silicon wafer (8) is greater than the pressure exerted by the fourth chamber (72) on the square silicon wafer (8).

8. The polishing head for square silicon wafers according to any one of claims 1 to 7, characterized in that: The buffer gasket ring (5) is provided with a plurality of adsorption holes (51) extending therethrough. The plurality of adsorption holes (51) are arranged at intervals along the circumference of the buffer gasket ring (5) and are arranged close to the inner ring of the buffer gasket ring (5).

9. The polishing head for square silicon wafers according to any one of claims 1 to 7, characterized in that: The thickness of the buffer ring (5) gradually increases from the inner ring to the outer ring.

10. Square silicon wafer polishing equipment, characterized in that: A polishing head for square silicon wafers comprising any one of claims 1-9.

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