Wafer fixing ring

Abstract

The utility model provides a wafer fixing ring. The wafer fixing ring is arranged at the end, close to the grinding pad, of the grinding head and used for fixing a wafer in the wafer fixing ring in the wafer grinding process. Comprising an annular body which is provided with a first surface and a second surface which are oppositely distributed; the multiple grinding parts protrude out of the first surface of the annular body and are arranged along the first surface of the annular body, the grinding parts comprise the first grinding part and the second grinding part, the inner wall of the first grinding part is flush with the inner wall of the annular body, a first distance is formed between the inner wall of the second grinding part and the inner wall of the annular body, and a second distance is formed between the inner wall of the second grinding part and the inner wall of the annular body; the inner wall of the second grinding part and the surface of the annular body jointly form a groove, and the two side walls, close to each other, of every two adjacent grinding parts and the first surface of the annular body jointly form a groove. According to the technical scheme, the groove is formed in the inner side of the second grinding part, so that more grinding liquid can reach the edge of the wafer, and the effective grinding of the edge of the wafer is realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of semiconductor, especially a wafer fixing ring. BACKGROUND

[0002] With the semiconductor device size decreasing, the wafer surface fluctuation caused by the multilayer interconnection or the deposition process with large filling depth is too large, which causes the difficulty of focusing in the photoetch process, weakens the control ability of line width, and reduces the consistency of line width on the whole wafer. Therefore, the industry introduces chemical mechanical polishing (CMP) to planarize the wafer surface. After the semiconductor manufacturing process enters the sub-micron field, chemical mechanical polishing has become an indispensable manufacturing process technology. In the chemical mechanical polishing process, the chemical mechanical polishing device has become one of the important equipment in the semiconductor process.

[0003] Chemical mechanical polishing is a planarization process for silicon wafers or other substrate materials in the processing process by using chemical corrosion and mechanical force. In the modern semiconductor production chemical mechanical polishing process, the wafer fixing ring on the polishing head is used to fix the wafer in the ring in the semiconductor wafer manufacturing polishing process to polish the single side of the wafer.

[0004] Please refer to Figures 1-2 , wherein, Figure 1 is a structural schematic view of an embodiment of a chemical mechanical polishing machine, Figure 2 is a structural schematic view of an embodiment of a wafer fixing ring. As Figure 1 shown, the chemical mechanical polishing machine includes a polishing head 11 and a polishing pad 12. The polishing head 11 is provided with a wafer fixing ring 13, which is used to fix the wafer 19 in the ring in the semiconductor wafer manufacturing polishing process to polish the single side of the wafer 19; wherein the arrow shows the rotation direction of the corresponding component. As Figure 2 shown, a fixed number and size of straight grooves 21 are arranged on the wafer fixing ring 13, and the grooves 21 allow a certain amount of polishing liquid to enter the wafer 19 fixed in the ring (refer to Figure 1The grinding by-product after the grinding is discharged through the groove 21. However, the by-product after the grinding is deposited in the groove 21, and the residue in the groove 21 is increased with the continuous grinding of the grinding pad 12. The surface of the wafer fixing ring 13 is also thinned due to the long-term grinding, and the wafer fixing ring 13 is a consumable material with a single life. The wafer 19 is surrounded by the wafer fixing ring 13. Due to the small flow of the grinding liquid on the surface of the wafer 19 and the small contact area between the wafer 19 and the grinding liquid, the wafer 19 is not fully ground, which affects the uniformity of the product and causes residues on the surface of the wafer 19.

[0005] Therefore, how to reduce the grinding by-product, improve the wafer edge grinding efficiency, and increase the life of the wafer fixing ring is a problem to be solved. SUMMARY

[0006] The technical problem to be solved by the utility model is how to reduce the grinding by-product, improve the wafer edge grinding efficiency, and increase the life of the wafer fixing ring, and a wafer fixing ring is provided.

[0007] In order to solve the above problems, the utility model provides a wafer fixing ring, which is arranged at one end of a grinding head close to a grinding pad, and is used for fixing a wafer in the wafer fixing ring in a wafer grinding process.

[0008] The technical scheme is characterized in that the inner wall of the second grinding part has a first interval with the inner wall of the annular body, the length of the groove is shortened, fresh grinding liquid can smoothly enter the wafer surface in the wafer fixing ring, and grinding by-products can be effectively discharged in time, so that the wafer surface is not damaged and the product yield is improved. The groove is formed in the inner side of the second grinding part, so that more grinding liquid can reach the edge of the wafer to effectively grind the edge of the wafer. Due to the existence of the groove, the contact area of the wafer fixing ring surface and the grinding pad is reduced, the grinding efficiency is improved, and the service life of the wafer fixing ring and the grinding pad is effectively prolonged. In addition, the groove can accommodate the by-products generated during grinding to some extent, so that the by-products remaining on the wafer surface are reduced. These by-products will cause product defects to a certain extent in different processes, produce various residues, and to a certain extent, reducing by-products is equivalent to improving the entire grinding environment, thereby reducing product defects and effectively ensuring the process yield stability of chemical mechanical grinding.

[0009] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. Techniques, methods and devices known to those skilled in the related art can not be discussed in detail, but should be considered as part of the authorization description under appropriate circumstances. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical scheme in the specific embodiment of the present application, the drawings needed in the description of the specific embodiment will be briefly introduced. Obviously, the drawings in the following description are only some specific embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creating labor.

[0011] Figure 1 The structure schematic diagram of an embodiment of a chemical mechanical polishing machine.

[0012] Figure 2 The structure schematic diagram of an embodiment of a wafer fixing ring.

[0013] Figure 3 The three-dimensional structure schematic diagram of an embodiment of the wafer fixing ring according to the present application.

[0014] Figure 4 The structure schematic diagram of an embodiment of the wafer fixing ring according to the present application. Figure 3 The enlarged view of part A in the figure.

[0015] Figure 5 The top view of an embodiment of the wafer fixing ring according to the present application.

[0016] BRIEF DESCRIPTION OF DRAWINGS

[0017] 30 annular body

[0018] 31 first grinding portion

[0019] 32 second grinding portion

[0020] 33 recess

[0021] 34 groove

[0022] 301 inner wall of annular body

[0023] 311 inner wall of first grinding portion

[0024] 321 inner wall of second grinding portion

[0025] L length of first spacing

[0026] W width of inner wall of second grinding portion

[0027] H height of second grinding portion

[0028] S1 first surface

[0029] S2 second surface DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0031] Please refer to Figures 3-5 , wherein, Figure 3 is a perspective structural schematic view of an embodiment of the wafer fixing ring of the present application; Figure 4 is Figure 3 is an enlarged view of part A in FIG. 1; Figure 5 is a top view of an embodiment of the wafer fixing ring of the present application. The wafer fixing ring is arranged at one end of the grinding head close to the grinding pad, and is used to fix the wafer in the wafer fixing ring in the wafer grinding process. As shown in FIG. 3, Figures 3-4As shown, the wafer fixing ring comprises a ring body 30 and a plurality of grinding portions. The ring body 30 has a first surface S1 and a second surface S2 oppositely distributed. The plurality of grinding portions protrude from the first surface S1 of the ring body 30 and are arranged along the first surface S1 of the ring body 30. The grinding portions include a first grinding portion 31 and a second grinding portion 32. An inner wall 311 of the first grinding portion 31 is flush with an inner wall 301 of the ring body 30. An inner wall 321 of the second grinding portion 32 has a first spacing L with the inner wall 301 of the ring body 30. The inner wall 321 of the second grinding portion 32 and the first surface of the ring body 30 jointly form a groove 33. Two side edge surfaces of two adjacent grinding portions 32 that are close to each other and the first surface of the ring body 30 jointly form a trench 34.

[0032] The first surface S1 of the ring body 30 is a surface of the ring body 30 close to the grinding pad. The second surface S2 of the ring body 30 is a surface of the ring body 30 close to the grinding head.

[0033] The above technical solution has the following advantages. The inner wall of the second grinding portion and the inner wall of the ring body have a first spacing, so that the length of the trench is shortened, the fresh grinding liquid can smoothly enter the wafer surface in the wafer fixing ring, the grinding by-products can be effectively discharged in time, the wafer surface is prevented from being damaged, and the product yield is improved. The groove formed in the inner side of the second grinding portion can make more grinding liquid reach the edge of the wafer, so as to effectively grind the edge of the wafer. Due to the existence of the groove, the contact area of the wafer fixing ring surface and the grinding pad is reduced, the grinding efficiency is improved, and the service life of the wafer fixing ring and the grinding pad is effectively prolonged. In addition, the groove can accommodate the by-products generated in the grinding to a certain extent, so that the by-products remaining on the wafer surface are reduced. These by-products will cause product defects to a certain extent in different processes, produce various residues, and to a certain extent, reducing the by-products is equivalent to improving the entire grinding environment, thereby reducing product defects and effectively ensuring the process yield stability of chemical mechanical grinding.

[0034] In some embodiments, the first grinding portion 31 and the second grinding portion 32 are alternately arranged, so as to avoid that the number of the second grinding portion 32 is too large or the distribution is too dense, thereby affecting the stability of the wafer fixing ring in fixing the wafer, so that the wafer fixing ring can stably grind and mechanically rotate, and does not affect the normal operation of the grinding head.

[0035] In some embodiments, the number of the grinding portions ranges from 18 to 22.

[0036] In some embodiments, the outer wall of the grinding portion has a width greater than the inner wall of the grinding portion; the outer wall of the grinding portion has a width ranging from 2.8 cm to 3.4 cm; and / or the inner wall of the grinding portion has a width ranging from 2.6 cm to 3.2 cm; and / or the side surface of the grinding portion has a width ranging from 1.8 cm to 2.2 cm; and / or the first interval has a length ranging from 0.2 cm to 0.5 cm.

[0037] In different process scenarios, the first interval can be further set according to the size of the target grinding rate to adjust the cross-sectional area S of the groove 33, as follows:

[0038] In some embodiments, when the target grinding rate is less than a first preset threshold, the length L of the first interval ranges from 0.2 cm to 0.28 cm. The length of the groove 33 is the length L of the first interval, and the width of the groove 33 is the width W of the second grinding portion. The cross-sectional area S of the groove is L*W, i.e., the cross-sectional area S of the groove ranges from (0.2 cm to 0.28 cm)*(2.6 cm to 3.2 cm). When the surface profile requirement of the wafer edge is low, i.e., under the condition that the required grinding rate of the process is low, the cross-sectional area S of the groove 33 can be set to be small, and under the premise of meeting the required flow of the grinding liquid for the wafer edge grinding, the surface area of the grinding portion 22 is increased, and the stability of the wafer fixing ring for fixing the wafer is improved.

[0039] In other embodiments, when the target grinding rate is greater than a second preset threshold, the length L of the first interval ranges from 0.26 cm to 0.38 cm, i.e., the cross-sectional area S of the groove ranges from (0.26 cm to 0.38 cm)*(2.6 cm to 3.2 cm). The second preset threshold is greater than the first preset threshold. When the surface profile requirement of the wafer edge is high, i.e., under the condition that the required grinding rate of the process is high, the cross-sectional area S of the groove 33 can be set to be large, so that more grinding liquid is gathered at the wafer edge, and the grinding effect on the wafer edge is improved.

[0040] In some embodiments, the height of the grinding portion 32 protruding from the first surface S1 of the annular body 30 ranges from 0.25 cm to 0.32 cm.

[0041] In different process scenarios, the height of the grinding portion 32 protruding from the first surface S1 of the annular body 30 can also be further set according to the size of the target grinding rate to adjust the volume V of the groove 33, as follows:

[0042] In some embodiments, when the target polishing rate is less than a first preset threshold, the length L of the first interval is in the range of 0.2 cm to 0.28 cm, and the height of the polishing portion protruding from the first surface S1 of the annular body 30 is in the range of 0.25 cm to 0.28 cm. The length L of the first interval is the length of the groove 33, the width W of the second polishing portion is the width of the groove 33, the height H of the second polishing portion is the depth of the groove, and the volume V of the groove is L*W*H, i.e., the volume of the groove is in the range of (0.2 cm to 0.28 cm)*(2.6 cm to 3.2 cm)*(0.25 cm to 0.28 cm). When the surface profile requirement of the wafer edge is low, i.e., under the condition that the polishing rate required by the process is low, the volume V of the groove 33 can be set to be small, and under the premise of meeting the polishing liquid flow required by the wafer edge polishing, the surface area of the polishing portion 22 is increased, and the stability of the wafer fixing ring in fixing the wafer is improved.

[0043] In other embodiments, when the target polishing rate is greater than a second preset threshold, the length L of the first interval is in the range of 0.26 cm to 0.38 cm, and the height of the polishing portion protruding from the first surface S1 of the annular body 30 is in the range of 0.28 cm to 0.32 cm. That is, the volume of the groove is in the range of (0.26 cm to 0.38 cm)*(2.6 cm to 3.2 cm)*(0.28 cm to 0.32 cm). The second preset threshold is greater than the first preset threshold. When the surface profile requirement of the wafer edge is high, i.e., under the condition that the polishing rate required by the process is high, the volume V of the groove 33 can be set to be large, so that more polishing liquid is gathered at the wafer edge, and the polishing effect on the wafer edge is improved.

[0044] In some embodiments, the annular body 30 is a circular ring. In other embodiments, the annular body 30 can also be a square ring or other ring shape.

[0045] In some embodiments, the outer wall of the polishing portion is flush with the outer wall of the annular body 30.

[0046] In some embodiments, the shape of the inner wall 321 of the second polishing portion 32 is adapted to the shape of the inner wall 301 of the annular body 30. In this embodiment, the shape of the inner wall 321 of the second polishing portion 32 is an arc-shaped curved surface. In other embodiments, the shape of the inner wall 321 of the second polishing portion 32 can also be a flat surface or a folded surface composed of two intersecting flat surfaces.

[0047] In some embodiments, the grooves 34 are straight grooves. In other embodiments, the grooves 34 can also be arc-shaped grooves, which make the groove direction more suitable for the flow path of the slurry into the retaining ring and the slurry byproducts out of the retaining ring, reduce the liquid flow obstruction and the accumulation of liquid in the grooves, improve the wafer polishing environment and thus improve the wafer polishing quality.

[0048] In some embodiments, the widths of the grooves 34 are equal. In other embodiments, the grooves 34 can also be arranged such that the width near the outer wall side of the polishing portion is greater than the width near the inner wall side of the polishing portion, i.e., the outer width is narrower than the inner width, which can make the slurry flow in smoothly, and at the same time, can make the slurry byproducts be thrown outwards under the action of centrifugal force, reducing the deposition of byproducts in the grooves.

[0049] It should be noted that reference to "one embodiment", "an embodiment", "example embodiment", "some embodiments", etc., in the specification indicates that a described embodiment can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of those skilled in the relevant art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0050] Generally, terms can be understood to be contextually used. For example, the term "one or more", as used in this document, can be used to describe any feature, structure, or characteristic in the singular or can be used to describe combinations of features, structures, or characteristics in the plural, depending on the context in which the term is used. Similarly, terms such as "a", "an", or "the" also can be understood to express a singular usage or to express a plural usage, depending on the context in which the terms are used. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but instead can also allow for existence of other factors not necessarily expressly described, again, depending on the context in which the term is used. It also should be noted in the description that "connected" or "coupled" can be used to indicate either a direct coupling or an indirect coupling between entities, and can include use of intermediate entities.

[0051] It should be noted that the terms "comprising" and "having" and their variants involved in the file of the present application are intended to cover non-exclusive inclusion. The terms "first", "second" and the like are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, unless the context clearly indicates otherwise, and it should be understood that such data used in this way can be interchanged under appropriate circumstances. In addition, the embodiments and features in the embodiments in the present application can be combined with each other without conflict. Furthermore, in the above description, the description of known components and technologies is omitted to avoid unnecessary confusion of the concept of the present application. In the above embodiments, each embodiment focuses on the difference from other embodiments, and the same / similar parts between the embodiments can be referred to each other.

[0052] The above is only the preferred embodiment of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A wafer retaining ring, disposed at one end of a grinding head near a grinding pad, for fixing a wafer within the wafer retaining ring during a wafer grinding process, characterized in that, include: The annular body has a first surface and a second surface that are relatively distributed. Multiple grinding portions protrude from the first surface of the annular body and are arranged along the first surface of the annular body. Each grinding portion includes a first grinding portion and a second grinding portion. The inner wall of the first grinding portion is flush with the inner wall of the annular body. The inner wall of the second grinding portion has a first distance from the inner wall of the annular body. The inner wall of the second grinding portion and the first surface of the annular body together form a groove. The side walls of two adjacent grinding portions that are close to each other together form a trench with the first surface of the annular body.

2. The wafer retaining ring according to claim 1, characterized in that, The first grinding section and the second grinding section are arranged alternately.

3. The wafer retaining ring according to claim 1, characterized in that, The number of grinding sections ranges from 18 to 22.

4. The wafer retaining ring according to claim 1, characterized in that, The width of the outer wall of the grinding part is greater than the width of the inner wall of the grinding part; The width of the outer wall of the grinding part ranges from 2.8cm to 3.4cm; and / or The width of the inner wall of the grinding part ranges from 2.6cm to 3.2cm; and / or The width of the sidewall of the grinding part ranges from 1.8cm to 2.2cm; and / or The length of the first spacing ranges from 0.2cm to 0.5cm.

5. The wafer retaining ring according to claim 4, characterized in that, When the target grinding rate is less than a first preset threshold, the length of the first spacing ranges from 0.2cm to 0.28cm.

6. The wafer retaining ring according to claim 4, characterized in that, When the target grinding rate is greater than a second preset threshold, the length of the first spacing ranges from 0.26cm to 0.38cm.

7. The wafer retaining ring according to claim 4, characterized in that, The height of the grinding part protruding from the first surface of the annular body ranges from 0.25cm to 0.32cm.

8. The wafer retaining ring according to claim 7, characterized in that, When the target grinding rate is less than a first preset threshold, the length of the first spacing ranges from 0.2cm to 0.28cm, and the height of the grinding part protruding from the first surface of the annular body ranges from 0.25cm to 0.28cm.

9. The wafer retaining ring according to claim 7, characterized in that, When the target grinding rate is greater than a second preset threshold, the length of the first spacing ranges from 0.26cm to 0.38cm, and the height of the grinding part protruding from the first surface of the annular body ranges from 0.28cm to 0.32cm.

10. The wafer retaining ring according to claim 1, characterized in that, The outer wall of the grinding part is flush with the outer wall of the annular body.

Images