CN114425743A

CN114425743A - Polishing pad and chemical mechanical polishing equipment

Info

Publication number: CN114425743A
Application number: CN202011173862.6A
Authority: CN
Inventors: 具滋贤; 张月; 杨涛; 卢一泓; 刘青
Original assignee: Institute of Microelectronics of CAS; Zhenxin Beijing Semiconductor Co Ltd
Current assignee: Institute of Microelectronics of CAS; Zhenxin Beijing Semiconductor Co Ltd
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2022-05-03

Abstract

The invention discloses a polishing pad and chemical mechanical polishing equipment, relates to the technical field of chemical mechanical polishing, and aims to reduce the frequency of replacing the polishing pad and improve the polishing efficiency under the condition of prolonging the service life of the polishing pad. The polishing pad includes a polishing layer. The polishing layer includes at least two polishing portions having different heights. The invention also provides chemical mechanical polishing equipment applied to the polishing pad.

Description

Polishing pad and chemical mechanical polishing equipment

Technical Field

The invention relates to the technical field of chemical mechanical polishing, in particular to a polishing pad and chemical mechanical polishing equipment.

Background

Chemical Mechanical Polishing (CMP) is a technique for global planarization of surfaces.

Polishing pads are one of the important components for achieving chemical mechanical polishing. There are instances where the polishing pad wears during use. If the worn polishing pad is continuously used, polishing efficiency and polishing quality are deteriorated. If the polishing pad is frequently replaced, the polishing efficiency is also lowered because the replacement of the polishing pad requires suspension of the chemical mechanical polishing operation.

Disclosure of Invention

The invention aims to provide a polishing pad and a chemical mechanical polishing device, which can reduce the frequency of replacing the polishing pad and improve the polishing efficiency under the condition of prolonging the service life of the polishing pad.

In order to achieve the above object, the present invention provides a polishing pad including a polishing layer. The polishing layer includes at least two polishing portions having different heights.

Compared with the prior art, the polishing pad provided by the invention comprises the polishing layer with at least two polishing parts with different heights, namely, the height difference is formed between the different polishing parts, and the height difference is more than 0. When the polishing pad provided by the invention is applied to wafer polishing, the surface of a wafer to be polished is firstly contacted with a higher polishing part and is not contacted with other polishing parts below the higher polishing part. At this time, only the higher polishing section participates in the polishing of the wafer, and the other polishing sections located below the higher polishing section do not participate in the polishing of the wafer. The height of the higher polishing portion participating in the wafer polishing is reduced as the higher polishing portion wears down as the polishing proceeds. When the height of the higher polishing section is lowered to coincide with the height of the polishing section having the smallest height difference therefrom, another polishing section located below the higher polishing section comes into contact with the surface of the wafer, and at this time, polishing of the wafer is mainly involved by the above-mentioned another polishing section. Therefore, after a certain polishing part included in the polishing pad provided by the invention is worn, another polishing part with the minimum height difference can continue to participate in the polishing of the wafer, and at the moment, the worn polishing pad is replaced without temporary polishing operation. Therefore, the frequency of replacing the polishing pad can be reduced, the polishing time of the polishing pad can be prolonged, and the polishing efficiency can be improved.

The invention also provides chemical mechanical polishing equipment, and the chemical mechanical polishing equipment is used for polishing the wafer. The chemical mechanical polishing device comprises a turntable, a grinding head, a polishing liquid conveying device and a polishing pad. The polishing pad is arranged on the bearing surface of the turntable. The grinding head is used for bearing the wafer. The polishing solution conveying device is used for conveying polishing solution to the polishing pad. The polishing pad is provided in any one of the implementations of the invention.

Compared with the prior art, the chemical mechanical polishing equipment provided by the invention has the same beneficial effects as the polishing pad in the technical scheme, and the detailed description is omitted.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural view of a chemical mechanical polishing apparatus provided in the related art;

FIG. 2 is a schematic diagram of a polishing pad according to an embodiment of the present invention;

FIG. 3 is a schematic top view of a polishing pad provided by an embodiment of the invention;

FIG. 4 is a schematic view showing a structure of a polishing section provided in a polishing pad according to an embodiment of the present invention;

FIG. 5 is a schematic view of another embodiment of a polishing pad provided in accordance with the present invention;

FIG. 6 is a schematic view showing a structure of a polishing section provided in a polishing pad according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a chemical mechanical polishing apparatus according to an embodiment of the present invention.

Wherein:

10-a turntable, 11-a grinding assembly, 12-a polishing solution conveying device;

13-polishing pad, 14-wafer, 15-polishing liquid;

2-polishing pad, 20-polishing layer, 200-polishing part;

200-1-higher polishing section, 200-2 lower polishing section;

2000-polishing column, 21-adhesion layer, 200 a-first polishing section;

200 b-a second polishing section, 200 c-a third polishing section, 2000 a-a first polishing column;

2000 b-second polishing column, 2000 c-third polishing column, c 1-first concentric circle;

c 2-second concentric circle, c 3-third concentric circle, cn-Nth concentric circle.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Various schematic diagrams of embodiments of the invention are shown in the drawings, which are not drawn to scale. Wherein certain details are exaggerated and possibly omitted for clarity of understanding. The shapes of various regions, layers, and relative sizes and positional relationships therebetween shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, as actually required.

In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

In addition, in the present invention, directional terms such as "upper" and "lower" are defined with respect to a schematically placed orientation of components in the drawings, and it is to be understood that these directional terms are relative concepts, which are used for relative description and clarification, and may be changed accordingly according to the change of the orientation in which the components are placed in the drawings.

In the present invention, unless expressly stated or limited otherwise, the term "coupled" is to be interpreted broadly, e.g., "coupled" may be fixedly coupled, detachably coupled, or integrally formed; may be directly connected or indirectly connected through an intermediate.

Chemical mechanical polishing is a surface planarization technique, which utilizes chemical mechanical polishing equipment to achieve the purpose of wafer surface planarization. Fig. 1 shows a schematic structural diagram of a chemical mechanical polishing apparatus provided in the related art. As shown in fig. 1, the chemical mechanical polishing apparatus may include a turntable 10, an abrasive assembly 11, a slurry delivery device 12, and a polishing pad 13.

The polishing pad 13 may be disposed on the carrying surface of the turntable 10 by means of adhesion. The polishing assembly 11 may support the wafer 14 by vacuum suction. The polishing liquid supply device 12 supplies the polishing liquid 15 to the polishing pad during the planarization process.

In actual use, the polishing assembly 11 carrying the wafer 14 may be pressed with a certain pressure against the rotating polishing pad 13 driven by the turntable 10. At this time, the polishing liquid supply device 12 continuously supplies the polishing liquid 15 to the polishing pad 13. The polishing liquid 15 is uniformly distributed on the surface of the polishing pad 13 by the centrifugal force of the polishing pad 13. A thin film of liquid is formed between the wafer 14 and the polishing pad 13, and the chemical components in the slurry 15 react with the wafer 14 to convert insoluble materials into readily soluble materials. The easily soluble substances are removed from the surface of the wafer 14 by micro-mechanical friction of particles and flow out of the polishing pad along with the polishing solution 15, so as to achieve the purpose of planarizing the surface of the wafer 14.

Referring to FIG. 1, prior art polishing pad 13 is a generally planar polishing pad. Local wear of the planar polishing pad occurs during use. If the flat polishing pad, which is locally worn, is continuously used, not only the polishing quality (e.g., flatness of the wafer) is affected, but also the polishing efficiency is lowered. When the polishing operation is suspended when the flat polishing pad is partially worn, the replacement of the polishing pad 13 will not only increase the polishing cost due to frequent replacement of the polishing pad 13, but also further decrease the polishing efficiency.

In view of the above technical problems, embodiments of the present invention provide a polishing pad. FIG. 2 is a schematic diagram illustrating a polishing pad according to an embodiment of the present invention. As shown in fig. 2, the polishing pad 2 according to the embodiment of the present invention includes a polishing layer 20, and the polishing layer 20 includes at least two polishing sections 200 having different heights. That is, there is a height difference between the different polishing portions 200, and the height difference is greater than 0.

The polishing layer 20 may include opposing upper and lower surfaces, and in practice, the upper surface of the polishing layer 20 is in contact with the wafer to effect polishing of the wafer. The lower surface of the polishing layer 20 can be adhesively attached to the carrying surface of a turntable of a chemical mechanical polishing apparatus. Alternatively, an adhesive layer 21 may be disposed on the lower surface of the polishing layer 20, and the adhesive layer 21 is adhered to the carrying surface of the turntable of the chemical mechanical polishing apparatus. The adhesive layer 21 may be provided on the lower surface of the polishing layer by means of adhesion. The adhesive layer 21 and the polishing layer 20 can also be formed into the polishing pad 2 provided by the embodiment of the invention by integral molding.

Referring to fig. 2, the outer edge profile of the polishing layer 20 may conform to the outer edge profile of the turntable, and is not particularly limited herein. For example, when the outer edge profile of the turntable is circular, the outer edge profile of the polishing layer 20 can also be circular. When the adhesive layer 21 is further disposed under the polishing layer 20, the outer edge profile of the adhesive layer 21 may also be rounded.

Referring to fig. 2, the material of the polishing layer 20 may be selected according to practical situations, and is not particularly limited, for example, the material of the polishing layer 20 may be polyurethane, etc.

Referring to fig. 2, the polishing layer 20 may be processed to form a plurality of polishing sections 200 of different heights. For example, when there are two polishing sections 200, one of the polishing sections 200 has a height value of H1, the other polishing section 200 has a height value of H2, and the difference between H1 and H2 is greater than 0.

Referring to fig. 4, for another example, when there are three polishing sections 200 (200 a, 200b, and 200c, respectively), each polishing section 200 has a height value, which may be H1, H2, and H3, respectively, wherein H1> H2> H3. At this time, the difference between H1 and H2 may be the same as or different from the difference between H2 and H3.

Referring to fig. 7, one of the two polishing portions shown in fig. 7 is defined as a higher polishing portion 200-1 and the other is defined as a lower polishing portion 200-2 for convenience of description. When the polishing pad 2 according to the embodiment of the present invention is applied to polishing a wafer 14, the surface of the wafer 14 to be polished is first in contact with the upper polishing section 200-1 and is not in contact with the lower polishing section 200-2 located below the upper polishing section 200-1. At this time, only the upper polishing section 200-1 participates in the polishing of the wafer 14, and the lower polishing section 200-2 does not participate in the polishing of the wafer 14. After the higher polishing portion 200-1 participating in the polishing of the wafer 14 is worn away as the polishing proceeds, the height of the higher polishing portion 200-1 is reduced. When the height of the upper polishing section 200-1 is lowered to coincide with the height of the lower polishing section 200-2, the lower polishing section 200-2 comes into contact with the surface of the wafer 14, and at this time, polishing of the wafer 14 is mainly involved by the lower polishing section 200-21. Based on this, after the higher polishing part 200-1 included in the polishing pad 2 provided by the embodiment of the present invention is worn, the lower polishing part 200-2 can continue to participate in the polishing of the wafer 14, and at this time, the worn polishing pad 2 is replaced without suspending the polishing operation. Therefore, the frequency of replacement of the polishing pad 2 can be reduced, the polishing time period of the polishing pad 2 can be prolonged, and the polishing efficiency can be improved.

The specific structure of the polishing section 200 is various, and the structure of the polishing section 200 will be described in detail below by taking the case where the polishing layer 20 includes three polishing sections 200 as an example, with reference to the accompanying drawings, it being understood that the following description is given by way of illustration only and not by way of limitation.

Referring to fig. 3 and 4, the polishing layer 20 includes a first polishing section 200a, a second polishing section 200b, and a third polishing section 200 c. The first polishing section 200a includes a plurality of first polishing columns 2000a, the second polishing section 200b includes a plurality of second polishing columns 2000b, and the third polishing section 200c includes a plurality of third polishing columns 2000 c.

Referring to fig. 3 and 4, the plurality of first polishing columns 2000a each have the same height value H1, and the plurality of first polishing columns 2000a have top surfaces that are flush. The plurality of second polishing columns 2000b have the same height value H2, and the plurality of second polishing columns 2000b have top surfaces that are flush. The plurality of third polishing columns 2000c have the same height value H3, and the plurality of third polishing columns 2000c have top surfaces that are flush. In the case of H1> H2> H3, the difference between H1 and H2 and the difference between H2 and H3 may be equal or unequal.

Referring to fig. 3 and 4, the polishing sections 200 may be formed of a plurality of first, second, and

third polishing columns

2000a, 2000b, and 2000c in an array, as viewed in a distributed manner. The outer edge profile of the polishing section 200 may be circular or square. A specific distribution form of the plurality of polishing columns (including the first polishing column 2000a, the second polishing column 2000b, and the third polishing column 2000c) included in the above-described polishing section 200 (including the first polishing section 200a, the second polishing section 200b, and the third polishing section 200c) can be explained by taking an example in which the outer edge profile of the array is circular. It is to be understood that the following examples are illustrative only and not limiting.

Referring to fig. 3 and 4, the circular profiles corresponding to the arrays may be concentric circles. For convenience of explanation, concentric circles from the outside to the inside may be defined as a first concentric circle c1, a second concentric circle c2, a third concentric circle c3, a … …, an nth concentric circle cn (N is a positive integer greater than 3), in this order.

Wherein, a plurality of first, second and

third polishing columns

2000a, 2000b and 2000c are uniformly distributed on each concentric circle (including the first concentric circle c1, the second concentric circle c2, the third concentric circle c3, … …, the nth concentric circle cn). A plurality of polishing pillars located on the same concentric circle are sequentially distributed in the order of the first polishing pillar 2000a, the second polishing pillar 2000b, and the third polishing pillar 2000 c.

Referring to fig. 3 and 4, as an example, a plurality of polishing rods distributed on the same concentric circle have a space therebetween. Moreover, there are also spaces between the polishing posts distributed on different concentric circles.

Referring to fig. 3 and 4, the space can be used as a space for storing polishing slurry, and more polishing slurry can be stored compared with the conventional planar polishing pad, thereby improving polishing efficiency and polishing quality. Moreover, the above-mentioned gap can also serve as a delivery passage for the polishing liquid as the polishing liquid circulates on the polishing pad 2, and the polishing liquid involved in the polishing can be sequentially discharged from the polishing pad 2 along the above-mentioned gap.

Referring to fig. 3 and 4, in the case where there are also spaces between the polishing posts located on the first concentric circle and between the polishing posts distributed on different concentric circles, the intervals between the adjacent polishing posts may be equal or may not be equal. When the intervals between the adjacent polishing columns are equal, the spaces formed by the intervals between the adjacent polishing columns can accommodate substantially the same amount of polishing liquid. In this case, the uniformity of the polishing of the wafer in different areas of the polishing layer can be improved, so as to optimize the polishing effect of the wafer.

Referring to fig. 3 and 4, each polishing rod may have a diameter greater than, equal to, or less than the spacing between adjacent polishing rods. It should be understood that the diameter of the polishing column herein is a diameter in a broad sense, for example, when the polishing column is a cylindrical polishing column, the diameter of the polishing column refers to the diameter of the bottom surface or the top surface of the cylindrical polishing column. When the polishing column is a square polishing column, the diameter of the polishing column refers to the length of the long side of the bottom surface or the top surface of the square polishing column. When the polishing column is a truncated cone-shaped polishing column, the diameter of the polishing column refers to the diameter of the bottom surface of the truncated cone-shaped polishing column. When the polishing column is an inverted-cone-frustum-shaped polishing column, the diameter of the polishing column refers to the diameter of the top surface of the inverted-cone-frustum-shaped polishing column. When the polishing column is the special-shaped polishing column, the diameter of the polishing column refers to the diameter corresponding to the maximum cross section of the special-shaped polishing column. The special-shaped polishing column can be a polishing column with different cross section shapes from bottom to top. When each of the polishing columns (including the first polishing column 2000a, the second polishing column 2000b, and the third polishing column 2000c) has a diameter larger than a pitch between adjacent polishing columns, the polishing columns may be distributed as much as possible on the polishing layer having the same area, and at this time, the area of a portion participating in wafer polishing is relatively large. Based on this, the polishing efficiency of the wafer can be improved.

As another example, referring to fig. 5 and 6, a plurality of polishing columns distributed on the same concentric circle abut against each other, and polishing columns distributed on different concentric circles may abut against each other or have a space.

Under the condition of adopting the technical scheme, because the polishing columns included by different polishing parts have height difference, and spaces are arranged among different polishing columns, when the polishing pad provided by the technical scheme is used for polishing a wafer, the spaces can contain polishing liquid. At this time, the amount of contained polishing liquid increases relative to the planar polishing pad provided in the related art, and based on this, polishing efficiency and polishing quality can be improved. Moreover, since the polishing columns included in different polishing portions may abut against each other, more polishing columns may be distributed on the same area of the polishing layer 200. At this time, the area of the polishing layer 200 actually participating in polishing can be increased. Based on this, polishing efficiency can be improved.

Referring to fig. 7, an embodiment of the present invention further provides a chemical mechanical polishing apparatus for polishing a wafer 14. The chemical mechanical polishing device comprises a turntable 10, a grinding head 11, a polishing liquid conveying device 12 and a polishing pad 2. The polishing pad 2 is disposed on a carrying surface provided on the turntable 10. The polishing head 11 is used for carrying a wafer 14. The polishing liquid delivery device 12 is used to deliver the polishing liquid 15 to the polishing pad 2. The polishing pad 2 is the polishing pad 2 provided by the embodiment of the present invention.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus embodiment, since it is substantially similar to the method embodiment, it is relatively simple to describe, and reference may be made to some descriptions of the method embodiment for relevant points.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A polishing pad, wherein the polishing pad comprises a polishing layer; the polishing layer includes at least two polishing portions having different heights.

2. The polishing pad according to claim 1, wherein the polishing layer comprises at least three polishing portions having different heights, the polishing portions being arranged in order of height; the height difference between adjacent polishing portions is the same or different.

3. The polishing pad according to claim 2, wherein each of the polishing portions comprises a plurality of polishing columns; the heights of a plurality of polishing columns of the same polishing part are the same, and the heights of the polishing columns of different polishing parts are different.

4. The polishing pad according to claim 3, wherein adjacent polishing portions have a space therebetween, or wherein adjacent polishing portions abut against each other.

5. The polishing pad according to claim 3, wherein a plurality of the polishing columns of the same polishing section have a space therebetween, or a plurality of the polishing columns of the same polishing section abut against each other.

6. The polishing pad according to claim 4 or 5, wherein adjacent polishing sections have a space therebetween, a plurality of polishing columns of the same polishing section have a space therebetween, and the spaces between adjacent polishing columns are the same or different.

7. The polishing pad of claim 3, wherein the polishing posts have a diameter greater than a spacing between adjacent polishing posts.

8. The polishing pad according to claim 3, wherein the polishing column is a cylindrical polishing column, a square polishing column, a truncated cone-shaped polishing column, an inverted truncated cone-shaped polishing column, or a shaped polishing column.

9. The polishing pad of claim 1, further comprising an adhesive layer disposed on a bottom surface of the polishing layer.

10. A chemical mechanical polishing apparatus, wherein the chemical mechanical polishing apparatus is used for polishing a wafer; the chemical mechanical polishing equipment comprises a turntable, a grinding head, a polishing solution conveying device and a polishing pad; the polishing pad is arranged on a bearing surface of the rotary disc; the grinding head is used for bearing the wafer; the polishing solution conveying device is used for conveying polishing solution to the polishing pad;

the polishing pad according to any one of claims 1 to 9.