Grinding head and polishing equipment

Abstract

The invention provides a grinding head and polishing equipment, the grinding head comprises a retaining ring and a wear-resistant and corrosion-resistant structure, the retaining ring is used for fixing a wafer therein, and one axial end surface of the retaining ring is a grinding surface; the multiple abrasion-resistant and corrosion-resistant structures are sequentially arranged on the grinding face at intervals in the circumferential direction of the retaining ring. When the retaining ring clamps the wafer to grind on the polishing pad of the polishing equipment, the plurality of wear-resistant and corrosion-resistant structures are sequentially arranged on the retaining ring, so that each area of the polishing pad through which the wafer passes can be ground, and byproducts generated in the grinding process can be taken away. By arranging a plurality of wear-resistant and corrosion-resistant structures on the retaining ring, the grinding head has the function of a trimmer, so that when a wafer is ground, an additional trimmer is not needed to grind a polishing pad, and the grinding efficiency is improved. The condition that the diamond particles on the trimmer fall on the polishing pad or the polishing pad is greatly scratched by the diamond particles when the grinding stress is large is avoided, and the rejection rate of wafers is reduced.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing equipment technology, and particularly to a retaining ring and polishing equipment. Background Technology

[0002] As technology nodes continue to advance, chemical mechanical polishing (CMP) requires more stable and efficient polishing rates and better intra-wafer uniformity. In the polishing process, the retaining ring of the polishing head is the most important mechanical component, and its polishing method directly affects the polishing rate of various areas of the wafer, especially the extreme edge of the wafer. Therefore, how to improve the polishing efficiency of the retaining ring has become a key engineering challenge.

[0003] The retaining ring of the polishing head is mainly used to fix the wafer during the CMP (Chemical Mechanical Polishing) process. The polishing slurry can be delivered to the interface between the polishing pad and the wafer through multiple grooves on the contact surface between the retaining ring and the polishing pad, improving the uniformity of material removal on the wafer surface. The polishing pad usually also has a dresser, which operates on various areas of the polishing pad through its own oscillation. The dresser itself is embedded with high-hardness diamond particles, which can effectively remove polishing byproducts from the polishing pad and, through a certain pressure, maintain a stable roughness on the polishing pad, thus maintaining a stable polishing rate. The materials of the retaining ring and the dresser have high wear and corrosion resistance, good mechanical properties, high machining accuracy, and dimensional stability.

[0004] Figure 1 This is a schematic diagram of polishing equipment in the prior art. Figure 2 This is a front view of a polishing apparatus in the prior art (dresser 50 is not shown). For details, see [link to relevant documentation]. Figure 1 and Figure 2In the prior art, polishing equipment used in CMP processes includes a grinding head, a polishing table 21, a polishing pad 22, and a dresser 50. The grinding head includes a mounting stage 13, a retaining ring 11, and a backing film 12. The polishing pad 22 is disposed on the polishing table 21. The retaining ring 11 and the backing film 12 are mounted on the mounting stage 13, with the backing film 12 located between the mounting stage 13 and the retaining ring 11. The wafer 30 is held within the retaining ring 11. The backing film 12 adsorbs and fixes the wafer 30. The rotation of the mounting stage 13 drives the retaining ring 11 to rotate, thereby driving the wafer 30 to rotate. The retaining ring 11 presses the wafer 30 against the surface of the polishing pad 22 for grinding. The way the retaining ring 11 holds the wafer 30 ensures that the wafer 30 is horizontally fixed and remains in a non-vibrational state during the polishing process. The polishing slurry 60, supplied continuously to the surface of the polishing pad 22, erodes and softens the surface of the wafer 30. Simultaneously, the polishing pad 22 continuously grinds and removes the softened portion of the wafer 30. During this process, the polishing table 21 drives the polishing pad 22 to rotate synchronously. Generally, the rotation direction of the polishing pad 22 is the same as the rotation direction of the retaining ring 11. The polishing slurry 60 contains abrasives and other chemical components. The abrasives are squeezed and rolled by the polishing pad 22 to scrape and grind the softened portion of the wafer 30 surface, obtaining a highly flattened wafer 30 surface. The polishing slurry containing abrasives drips from above the polishing pad 22 onto its surface. Under the rotation of the polishing pad 22 and the sweeping motion of the adjusting disk 40, it spreads across the entire surface of the polishing pad 22. The polishing slurry 60 enters the contact gap between the wafer 30 and the polishing pad 22 through the grooves on the retaining ring 11, performing the grinding work and improving the uniformity of material removal on the surface of the wafer 30. The sweeping method of the adjustment disc 40 is, for example, horizontal movement, so as to spread the polishing liquid evenly. The material of the adjustment disc 40 is a flexible material.

[0005] See Figure 3 The polishing pad 22 rotates, and the retaining ring 11 clamps the wafer, causing it to rotate. The retaining ring 11 also drives the wafer to move horizontally relative to the polishing pad 11 (e.g., by swinging back and forth). Byproducts generated during wafer polishing fall into the grooves on the surface of the polishing pad 22. The dresser 50 acts on various areas of the polishing pad 22 through its own oscillation (reciprocating movement on the polishing pad 22). The diamond particles embedded in the dresser 50 have high hardness and can penetrate into the grooves of the polishing pad 22. The oscillation of the dresser 50 effectively removes the grinding byproducts from the grooves of the polishing pad 22. Furthermore, the dresser 50 applies a certain downward pressure to the polishing pad 22 during the oscillation process. Thus, the oscillation of the dresser 50 and the rotation of the polishing pad 22 result in a stable surface roughness for the polishing pad 22, maintaining a stable polishing rate. The materials of the retaining ring 11 and the dresser 50 have high wear and corrosion resistance, good mechanical properties, high machining accuracy, and dimensional stability.

[0006] Therefore, the existing technical solution is to use a separately operating dresser 50 to polish the polishing pad 22, maintaining the activation level and polishing rate of the polishing pad 22 surface, while removing polishing byproducts. However, the dresser 50 requires a long polishing time and path, and its coverage is greatly affected by the setting of the movement path. If the setting is not appropriate, the polishing may be incomplete, resulting in an unstable polishing rate. Because the dresser 50 is coated with diamond particles, if the bonding is not strong enough or the polishing stress is high, it is easy to cause large scratches on the polishing pad 22, affecting the polishing state of the wafer 30 and causing a loss of wafer 30 yield. Summary of the Invention

[0007] The purpose of this invention is to provide a grinding head and polishing equipment to solve the problem in the prior art that polishing equipment using a dresser to grind the polishing pad is prone to causing large scratches on the polishing pad due to diamond particles on the dresser, which affects the yield of the wafer.

[0008] To address the aforementioned technical problems, based on one aspect of the present invention, a grinding head is provided, comprising:

[0009] A retaining ring is used to hold the wafer in place, and one axial end face of the retaining ring is a ground surface;

[0010] A wear-resistant and corrosion-resistant structure, wherein multiple wear-resistant and corrosion-resistant structures are arranged sequentially and at intervals along the circumference of the retaining ring on the grinding surface.

[0011] Optionally, the grinding surface is provided with grooves that penetrate the radial inner side and radial outer side of the retaining ring, and a plurality of grooves are arranged sequentially at intervals along the circumference of the retaining ring.

[0012] Optionally, a wear-resistant and corrosion-resistant structure is provided on the grinding surface between each pair of adjacent grooves.

[0013] Optionally, the groove is located at one end radially outside the retaining ring as a liquid inlet, the groove is straight, and the angle between the retaining ring at the liquid inlet and the extension direction of the groove is acute; or, the groove is arc-shaped, and the angle between the retaining ring at the liquid inlet and the groove at the liquid inlet is acute.

[0014] Optionally, the wear-resistant and corrosion-resistant structure includes an array structure and a wear-resistant and corrosion-resistant coating. The array structure is fixed on the grinding surface, and the wear-resistant and corrosion-resistant coating is disposed on the array structure.

[0015] Optionally, the material of the wear-resistant and corrosion-resistant coating includes silicon carbide and silicon nitride.

[0016] Optionally, the array structure includes multiple structural units arranged in an array, the structural units being protruding, and the protrusion direction of the structural units being away from the grinding surface along the axial direction of the retaining ring.

[0017] According to another aspect of the present invention, a polishing apparatus is also provided, comprising:

[0018] A polishing assembly having a polishing surface, the polishing assembly being rotatable about the central vertical line of the polishing surface;

[0019] As described above, the grinding head has a retaining ring for pressing the wafer against the polishing surface, and the grinding surface of the retaining ring is in contact with the polishing surface. The retaining ring can rotate about its own axis and can move on the polishing surface.

[0020] Optionally, the grinding head further includes a back film disposed on the other axial end face of the retaining ring, the back film being used to adsorb the wafer.

[0021] Optionally, the polishing assembly includes a polishing table and a polishing pad, the polishing pad being disposed on the polishing table, the surface of the polishing pad being configured as the polishing surface, and the polishing table being rotatable to drive the polishing pad to rotate.

[0022] As shown above, when the retaining ring holds the wafer and grinds it on the polishing pad of the polishing equipment, the multiple wear-resistant and corrosion-resistant structures sequentially arranged on the retaining ring can polish each area of ​​the polishing pad that the wafer passes through, and remove the by-products generated during the grinding process. This invention, by setting multiple wear-resistant and corrosion-resistant structures on the retaining ring, allows the grinding head to also function as a dresser. Therefore, when grinding the wafer, there is no need for an additional dresser to polish the polishing pad, nor is it necessary to consider the design of the dresser's movement path. This avoids the situation where diamond particles from the dresser fall onto the polishing pad or cause significant scratches to the polishing pad when the grinding stress is high, thus reducing the wafer scrap rate.

[0023] It should be noted that since the polishing equipment includes the retaining ring, it also has the technical effects brought by the retaining ring, which will not be repeated here. Attached Figure Description

[0024] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0025] Figure 1 This is a schematic diagram of polishing equipment in the prior art;

[0026] Figure 2This is a front view of a polishing device in the prior art (the dresser is not shown).

[0027] Figure 3 This is a top view of a polishing device in the prior art;

[0028] Figure 4 This is a schematic diagram of a wear-resistant and corrosion-resistant structure disposed on a retaining ring according to an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of an array structure according to an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0031] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. “One end” and “the other end,” as well as “proximal end” and “distal end,” generally refer to two corresponding parts, including not only endpoints. The terms “installed,” “connected,” and “joined” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral part; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements or an interaction between two elements. Furthermore, as used in this invention, the phrase "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] Figure 4 This is a schematic diagram of a grinding head according to an embodiment of the present invention, see reference. Figure 4 The polishing head of the present invention includes a retaining ring 11 and wear-resistant and corrosion-resistant structures 14. The retaining ring 11 is used to fix the wafer 30 inside it. One axial end face of the retaining ring 11 is a polishing surface 110, which is used to contact the surface of the polishing pad 22. A plurality of wear-resistant and corrosion-resistant structures 14 are sequentially and spaced apart on the polishing surface 110 along the circumference of the retaining ring 11. Understandably, the material of the contact surface between the wear-resistant and corrosion-resistant structure 14 and the surface of the polishing pad 22 is a material with high wear resistance and corrosion resistance. The polishing head also includes a mounting stage and a backing film. For details about the mounting stage and backing film, please refer to the foregoing description, which will not be described again here.

[0033] Thus, when the retaining ring 11 holds the wafer 30 and grinds it on the surface of the polishing pad 22, based on the rotation of the retaining ring 11 and its oscillation on the surface of the polishing pad 22 (e.g., left-right and back-forward oscillation), the multiple wear-resistant and corrosion-resistant structures 14 sequentially arranged on the retaining ring 11 can grind each area of ​​the polishing pad 22 through which the wafer 30 passes, and remove the grinding byproducts that fall into the grooves on the surface of the polishing pad 22 during the grinding process. Furthermore, since the retaining ring 11 always covers the wafer 30, the wear-resistant and corrosion-resistant structures 14 provide a better grinding effect on each area of ​​the polishing pad 22 through which the wafer 30 passes compared to the dresser 50. By setting multiple wear-resistant and corrosion-resistant structures 14 on the retaining ring 11, the present invention enables the grinding head to also function as a dresser 50. Therefore, when grinding the wafer 30, there is no need for an additional dresser 50 to grind the polishing pad 22, nor is it necessary to consider the design of the movement path of the dresser 50. This avoids the situation where diamond particles on the dresser 50 fall onto the polishing pad 22 or cause significant scratches to the polishing pad 22 when the grinding stress is high, thereby reducing the scrap rate of the wafer 30.

[0034] Continue reading Figure 4 The grinding surface 110 is provided with grooves 111, which penetrate the radial inner side and radial outer side of the retaining ring 11. Multiple grooves 111 are arranged sequentially at intervals along the circumference of the retaining ring 11. The polishing fluid enters the contact gap between the wafer and the polishing pad through the grooves 111 to perform the grinding work.

[0035] In one embodiment, the end of the groove 111 located radially outward of the retaining ring 11 is the liquid inlet. The groove 111 is straight, and the angle α formed by the tangential direction of the retaining ring 11 at the liquid inlet and the extending direction of the groove 111 is an acute angle. This configuration, after determining the rotation direction of the retaining ring 11, allows the grinding fluid to more smoothly pass through the groove 111 and enter the interior of the retaining ring 11 during rotation. It should be noted that the rotation direction of the retaining ring 11 must satisfy the following condition: the liquid inlet of the groove 11 is located in front of the end of the groove 11 located radially inward of the retaining ring 11 in the direction of rotation. For example, Figure 4 The demonstrated retaining ring 11 rotates clockwise, with the inlet located at the radially inner end of the groove 11 relative to the retaining ring 11, in front of it in the clockwise direction. Alternatively, the groove 111 can be arc-shaped, with an acute angle formed between the tangent of the retaining ring 11 at the inlet and the tangent of the groove 111 at the inlet. The arc-shaped groove 111 can also achieve the same function as the straight groove 111.

[0036] Continue reading Figure 4 A wear-resistant and corrosion-resistant structure 14 is provided on the grinding surface 110 between each two adjacent grooves 111. This can avoid the mutual interference between the grooves 111 and the wear-resistant and corrosion-resistant structure 14 during the grinding process, and ensure that the wear-resistant and corrosion-resistant structure 14 polishes the polishing pad 22 without affecting the polishing liquid 60 from the grooves 111 into the contact gap between the wafer 30 and the polishing pad 22.

[0037] Furthermore, the wear-resistant and corrosion-resistant structure 14 includes an array structure 140 and a wear-resistant and corrosion-resistant coating (not shown). The array structure 140 is fixed on the grinding surface 110, and the wear-resistant and corrosion-resistant coating is disposed on the array structure 140. The materials of the wear-resistant and corrosion-resistant coating include silicon carbide and silicon nitride.

[0038] Figure 5 This is a schematic diagram of an array structure according to an embodiment of the present invention. (See attached diagram.) Figure 5 The arrayed structural component 140 includes multiple structural units 141 arranged in an array. The structural units 141 are protruding, and the protrusion direction of the structural units 141 is away from the grinding surface 110 along the axial direction of the retaining ring 11. In this way, the protrusion of the structural units 141 can increase the surface roughness of the wear-resistant and corrosion-resistant structure 14, and improve the polishing effect on the polishing pad 22 under the action of the wear-resistant and corrosion-resistant coating.

[0039] Based on the aforementioned grinding head, an embodiment of the present invention also provides a polishing apparatus. The polishing apparatus includes a grinding head and a polishing assembly as described above. The polishing assembly has a polishing surface 220 and is rotatable about the central vertical line of the polishing surface 220. A retaining ring 11 of the grinding head is used to press a wafer 30 onto the polishing surface 220, and the grinding surface 110 of the retaining ring 11 contacts the polishing surface 220. The retaining ring 11 is rotatable about its own axis and can move on the polishing surface 220. The polishing assembly includes a polishing table 21 and a polishing pad 22. The polishing pad 22 is disposed on the polishing table 21, and its surface is configured as the polishing surface 220. The polishing table 21 is rotatable to drive the polishing pad 22 to rotate. For details regarding the polishing apparatus of the present invention, please refer to the foregoing description. Figure 1 and Figure 2 The descriptions of the corresponding components will be further explained here, and will not be elaborated upon further.

[0040] While the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A grinding head, characterized in that, include: A retaining ring is used to hold the wafer in place, and one axial end face of the retaining ring is a ground surface; Multiple wear-resistant and corrosion-resistant structures are arranged sequentially and at intervals along the circumference of the retaining ring on the grinding surface.

2. The grinding head according to claim 1, characterized in that, The grinding surface is provided with grooves that penetrate the radial inner side and radial outer side of the retaining ring, and a plurality of grooves are arranged sequentially at intervals along the circumference of the retaining ring.

3. The grinding head according to claim 2, characterized in that, A wear-resistant and corrosion-resistant structure is provided on the grinding surface between each pair of adjacent grooves.

4. The grinding head according to claim 2, characterized in that, The groove is located at one end radially outside the retaining ring as the liquid inlet. The groove is straight, and the angle between the retaining ring at the liquid inlet and the extension direction of the groove is acute. Alternatively, the groove is arc-shaped, and the angle between the retaining ring at the liquid inlet and the groove at the liquid inlet is acute.

5. The grinding head according to claim 1, characterized in that, The wear-resistant and corrosion-resistant structure includes an array structure and a wear-resistant and corrosion-resistant coating. The array structure is fixed on the grinding surface, and the wear-resistant and corrosion-resistant coating is disposed on the array structure.

6. The grinding head according to claim 5, characterized in that, The materials of the wear-resistant and corrosion-resistant coating include silicon carbide and silicon nitride.

7. The grinding head according to claim 5, characterized in that, The array structure includes multiple structural units arranged in an array. The structural units are protruding, and the protrusion direction of the structural units is away from the grinding surface along the axial direction of the retaining ring.

8. A polishing device, characterized in that, include: A polishing assembly having a polishing surface, the polishing assembly being rotatable about the central vertical line of the polishing surface; The grinding head according to any one of claims 1-7, wherein the retaining ring is used to press the wafer against the polishing surface, and the grinding surface of the retaining ring is in contact with the polishing surface, the retaining ring is rotatable about its own axis, and the retaining ring is movable on the polishing surface.

9. The polishing equipment according to claim 8, characterized in that, The grinding head also includes a back film disposed on the other axial end face of the retaining ring, and the back film is used to adsorb the wafer.

10. The polishing equipment according to claim 8, characterized in that, The polishing assembly includes a polishing table and a polishing pad. The polishing pad is disposed on the polishing table, and the surface of the polishing pad is configured as the polishing surface. The polishing table is rotatable to drive the polishing pad to rotate.

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