A polishing pad having grooves on the surface

Abstract

The present invention relates to the technical field of chemical mechanical polishing, and discloses a polishing pad with grooves on the surface, which comprises a circular polishing layer, on which a first groove, a second groove and a third groove are arranged; the first groove is located on the surface of the polishing layer, and the first groove is spirally extended to the edge of the polishing layer with the center of the polishing layer as the starting point; the second groove is located on the surface of the polishing layer, and the second groove is radially extended to the edge of the polishing layer with the center of the polishing layer as the starting point; the third groove is located on the surface of the polishing layer, and the third groove is extended to the edge of the polishing layer with a certain point on the second groove as the starting point. The polishing pad of the embodiment of the present invention can control the tangential acceleration of the polishing liquid through the first groove extending in a spiral shape, realize the uniform distribution of the polishing liquid, and improve the removal rate, and can adjust the radial acceleration of the polishing liquid through the second groove extending in a radial direction and the third groove bifurcated with the second groove, delay the change of the polishing liquid speed, and improve the residence time of the polishing liquid.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, in particular to a polishing pad with grooves on the surface. Background Art

[0002] With the development of silicon integrated circuit technology industry, the size of silicon wafers used has increased due to cost, the integration of electronic components on them has increased, and the feature size of devices has continued to shrink. In order to ensure the quality of lithography during the preparation of silicon wafers, the surface flatness of silicon wafers must reach the nanometer level. Chemical mechanical polishing is currently the only method that can achieve global flattening of silicon wafers. Polishing pads are important consumables in the chemical mechanical polishing process. They undertake the functions of physical polishing and transporting polishing liquid, and their quality directly affects the polishing effect.

[0003] The grooves on the polishing pad surface play an important role in improving pressure distribution, heat transfer, increasing liquid carrying capacity, polishing efficiency, etc. The width, depth, shape, etc. of the surface grooves all affect the polishing effect of the polishing pad, among which the groove shape has the greatest impact, and its design is particularly important. At present, common groove shapes include grid type, ring type, spiral type, involute type, radial type, and combinations of the above shapes.

[0004] Existing polishing pads have the following problems: due to the circular motion of the polishing pad, the polishing liquid will inevitably accelerate when moving from the center to the outside. The higher polishing liquid movement speed will not only cause the problem of low polishing liquid utilization, but also cause over-polishing at the edge, affecting the polishing quality. Summary of the invention

[0005] The object of the present invention is to provide a polishing pad having grooves on its surface, which can adjust the acceleration of the flow of the polishing liquid and delay the change of the polishing liquid speed, so as to overcome the problems in the background technology.

[0006] In order to achieve the above object, the present invention provides a polishing pad having grooves on its surface, comprising:

[0007] A polishing layer, wherein the polishing layer is circular;

[0008] A first groove is located on the surface of the polishing layer, and the first groove takes the center of the polishing layer as a starting point and extends spirally to the edge of the polishing layer;

[0009] A second groove is located on the surface of the polishing layer, and the second groove takes the center of the polishing layer as a starting point and extends radially to the edge of the polishing layer;

[0010] The third groove is located on the surface of the polishing layer, and the third groove takes a certain point on the second groove as a starting point and extends to the edge of the polishing layer.

[0011] Furthermore, the first groove is a centrally symmetrical double-spiral structure.

[0012] Furthermore, the radial spacing of the first grooves is L1. Wherein 1≤a≤15, θ is the angle between a straight line connecting any point of the first groove to the center of the circle and the horizontal direction, 0≤θ≤nΠ, and n is an integer.

[0013] Furthermore, the width of the first groove is D1, 1mm≤D1≤3mm; the depth of the first groove is H1, 0.5mm≤H1≤2mm.

[0014] Furthermore, the width of the second groove is D2, D2=D1; the depth of the second groove is H2, H2≥H1.

[0015] Furthermore, the width of the third groove is D3, D3=D2; the depth of the third groove is H3, H3=H2.

[0016] Furthermore, there are a plurality of the second grooves, and the plurality of the second grooves are evenly distributed along the circumference of the polishing layer.

[0017] Furthermore, there are a plurality of the third grooves, and the plurality of the third grooves are evenly distributed along the second groove.

[0018] Furthermore, the second groove and the third groove are both straight-line or curved.

[0019] Furthermore, the shape of the middle area of ​​the second groove and / or the third groove is a sinusoidal function shape.

[0020] The polishing pad with grooves on the surface provided by the above technical solution has the following beneficial effects compared with the prior art: by arranging a first groove extending in a spiral shape on the polishing layer, the tangential acceleration of the polishing liquid can be regulated, thereby improving the liquid storage capacity of the polishing pad; by the second groove extending radially and the third groove forked from the second groove, the radial acceleration of the polishing liquid can be adjusted, the change in the speed of the polishing liquid can be delayed, the polishing uniformity can be improved, and then the edge over-polishing can be prevented, the utilization rate of the polishing liquid can be improved, and the polishing quality can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a polishing pad according to a first embodiment of the present invention;

[0022] Figure 2a is a schematic structural diagram of a polishing pad according to a second embodiment of the present invention;

[0023] Figure 2b yes Figure 2a Sectional view along section A-A;

[0024] Figure 2c yes Figure 2a Sectional view along section B-B;

[0025] Figure 3 is a schematic structural diagram of a polishing pad according to a third embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of the structure of the polishing pad of the fourth embodiment of the present invention.

[0027] Among them, 1 is polishing layer, 2 is second grinding area, 3 is first groove, 4 is second groove, 5 is third groove, 6 is first grinding area, and 7 is third grinding area. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used in the present invention to indicate the orientation or position relationship is based on the orientation or position relationship shown in the drawings, and 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 operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Combination Figures 1 to 4As shown, the present invention provides a polishing pad with grooves on the surface, which includes a circular polishing layer 1, on which a first groove 3, a second groove 4 and a third groove 5 are arranged; the first groove 3 is located on the surface of the polishing layer 1, and the first groove 3 takes the center of the polishing layer 1 as a starting point and extends spirally to the edge of the polishing layer 1; the second groove 4 is located on the surface of the polishing layer 1, and the second groove 4 takes the center of the polishing layer 1 as a starting point and extends radially to the edge of the polishing layer 1; the third groove 5 is located on the surface of the polishing layer 1, and the third groove 5 takes a certain point on the second groove 4 as a starting point and extends to the edge of the polishing layer 1.

[0032] Based on the above scheme, by setting a first groove 3 extending in a spiral shape on the polishing layer 1, the tangential acceleration of the polishing liquid can be regulated and the liquid storage capacity of the polishing pad can be improved; by the radially extending second groove 4 and the third groove 5 forked with the second groove 4, the radial acceleration of the polishing liquid can be adjusted, the change of the polishing liquid speed can be delayed, the polishing uniformity can be improved, and then the edge over-polishing can be prevented, the utilization rate of the polishing liquid can be improved, and the polishing quality can be guaranteed.

[0033] Specifically, the first grooves 3 can improve the liquid storage capacity of the polishing pad, so that the polishing liquid is evenly distributed in the circumferential direction; the spacing and the inclination angle of the first grooves 3 are controllable, and by adjusting the spacing and the inclination angle of the first grooves 3, the tangential acceleration of the flow of the polishing liquid is adjusted, the polishing uniformity is improved, and the edge over-polishing is prevented;

[0034] The second groove 4 can improve the polishing ability of the polishing pad, so that the polishing liquid flows radially toward the edge to prevent debris from being deposited;

[0035] The third grooves 5 can extend the residence path of the polishing liquid, increase the residence time of the polishing liquid, and save the amount of polishing liquid. The number and inclination angle of the third grooves 5 are adjustable. By controlling the number and inclination angle of the third grooves 5, the radial acceleration of the polishing liquid flow is adjusted, the polishing uniformity is improved, and edge over-polishing is prevented.

[0036] Furthermore, the first groove 3 is a centrally symmetrical double spiral structure, and the first groove 3 of the double spiral structure has no end with a breakpoint at the center of the polishing layer 1, but remains connected, which facilitates the flow of the polishing liquid and ensures its uniformity.

[0037] In order to better understand and implement the present invention, the specific implementation of the polishing pad of the present invention is described in detail below through different embodiments.

[0038] Embodiment 1

[0039] like Figure 1As shown, the polishing pad provided in this embodiment includes a substrate layer (not shown in the figure) and a polishing layer 1, and the surface of the polishing layer 1 is provided with a first groove 3, a second groove 4 and a third groove 5. The first groove 3 is a double spiral starting from the center of the circle, and the width of the first groove 3 is D1, 1mm≤D1≤3mm, for example, it can be 1mm, 1.5mm, 1.7mm, 2.1mm, 2.4mm, 3mm, etc. The depth of the first groove 3 is H1, 0.5mm≤H1≤2mm, for example, it can be 0.5mm, 0.7mm, 1.2mm, 1.8mm, 2mm, etc. The radial spacing of the first groove 3 is Wherein, a is a parameter, 1≤a≤15, θ is the angle between a straight line connecting any point of the first groove 3 to the center of the circle and the horizontal direction, 0≤θ≤nΠ, and n is an integer. Wherein, the radial spacing of the first grooves 3 is the same.

[0040] Please continue reading Figure 1 , the second groove 4 is distributed along the radial direction, and its width D2=D1, depth H2=H1+c, 0.51mm≤c≤0.21mm, H2 can be 0.52mm, 0.72mm, 1.22mm, 1.82mm, 2.02mm, etc. The width D3=D2 of the third groove 5, the depth H3=H2, the acute angle between the third groove 5 and the second groove 4 is α, preferably α is one of 30°, 45°, 60°. The second grooves 4 are evenly distributed on the polishing pad, the number is 2J, 1≤J≤8. The third grooves 5 are distributed along the second grooves 4, the number is K, K=nJ, 1≤n≤5. The third grooves 5 are evenly distributed on the odd number of second grooves 4.

[0041] It should be noted that the length, width, height, spacing and α of the grooves in this embodiment can be referred to Figure 2a - Figure 2c The meanings of the figure marks in this embodiment and in the second embodiment are the same.

[0042] Assuming that the polishing pad rotates clockwise in the same direction as the wafer in the CMP process, under the action of centrifugal force, the polishing liquid flows from the center to the edge along the first groove 3 and is evenly distributed on the polishing pad; by adjusting the spacing of the first groove 3, the tangential acceleration of the polishing liquid can be effectively regulated, thereby improving the polishing quality. The second groove 4 transports the polishing liquid in the radial direction, accelerates the flow of the polishing liquid, and takes away the debris generated during the polishing process; the groove depth of the second groove 4 is greater than the groove depth of the first groove 3, which prevents the debris from being deposited at the groove interface and reduces scratches on the wafer surface. The third groove 5 is distributed on the polishing pad at different angles along the second groove 4, effectively diverting the polishing liquid transported by the second groove 4. By adjusting the number and inclination angle of the third groove 5, the radial acceleration of the flow of the polishing liquid can be regulated, the pressure distribution can be improved, and the polishing quality can be improved. This embodiment also effectively improves the polishing efficiency by increasing the transportation path of the polishing liquid.

[0043] Embodiment 2

[0044] like Figure 2a - Figure 2c As shown, the polishing pad provided in this embodiment is different from that in the first embodiment only in that the spacing between the first grooves 3 gradually decreases in the radial direction from the center of the polishing layer 1 .

[0045] Specifically, when the spacing of the first grooves 3 is equal, the speed of the polishing liquid will gradually increase when it moves toward the edge, which will cause a certain degree of uneven polishing. After the spacing of the first grooves 3 is adjusted to decrease in the radial direction in this embodiment, the change in the tangential speed of the polishing liquid flowing along the grooves is effectively delayed, which effectively improves the tangential speed distribution of the polishing liquid and reduces the uneven polishing phenomenon.

[0046] The other parts of this embodiment are the same as those of the first embodiment and will not be described in detail.

[0047] Embodiment 3

[0048] like Figure 3 As shown, the polishing pad provided in this embodiment is different from that in the second embodiment only in that the shape of the middle area of ​​the second groove 4 is a sinusoidal function shape.

[0049] Specifically, the area at the center of the surface of the polishing layer 1 can be set as the first polishing area 6, the area at the edge can be set as the third polishing area 7, the area between the first polishing area 6 and the third polishing area 7 can be set as the second polishing area 2, and the middle area of ​​the second groove 4 is basically located in the second polishing area 2. The polishing liquid flows outward from the center of the circle along the second groove 4 in a straight line in the first polishing area 6, which effectively improves the problem of uneven pressure distribution in the central area; the polishing liquid flows outward along the sinusoidal trajectory of the second groove 4 in the second polishing area 2, which effectively increases the contact time between the polishing liquid and the wafer and improves the utilization rate of the polishing liquid; the polishing liquid flows outward along a straight line in the third polishing area 7, which effectively removes the polishing liquid after processing and prevents debris deposition.

[0050] The other parts of this embodiment are the same as those of the second embodiment and will not be described in detail.

[0051] Embodiment 4

[0052] like Figure 4 As shown, the polishing pad provided in this embodiment is different from that in the second embodiment only in that the second groove 4 and the third groove 5 are both curved.

[0053] Specifically, the second groove 4 is an involute type, and the rectangular coordinates of the second groove 4 are defined as (R*(cos(t)+t.*sin(t)), R*(sin(t)-t.*cos(t)), where 10mm≤R≤30mm, for example, R can be one or more of 15mm, 21mm, 25mm, 28mm; 0≤t≤Π, for example, it can be one or more of Π / 5, Π / 4, Π / 3, Π / 2. The second grooves 4 are evenly distributed on the polishing pad, with a number of 2M and 1≤M≤8.

[0054] The third grooves 5 are also involute-shaped and are distributed along the second grooves 4 . The number of the third grooves 5 is N, where N=nM, 1≤n≤5. The third grooves 5 are evenly distributed on the odd-numbered second grooves 4 .

[0055] The involute second groove 4 and the third groove 5 further increase the flow path of the polishing liquid and improve the utilization rate of the polishing liquid. In addition, the above-mentioned design of the second groove 4 and the third groove 5 slows down the linear velocity change rate of the polishing liquid along the axial direction, further ensures the uniform flow of the polishing liquid and improves the polishing effect.

[0056] In summary, the embodiments of the present invention provide a polishing pad having grooves on its surface, which regulates the tangential acceleration of the polishing pad through the centrally symmetrical double spiral grooves, and regulates the radial acceleration of the polishing pad through the radial forked grooves, thereby delaying the change in polishing liquid speed and improving polishing uniformity.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A polishing pad having grooves on its surface, characterized in that: include: A polishing layer, wherein the polishing layer is circular; a first groove, located on the surface of the polishing layer, the first groove extending in a spiral shape from the center of the polishing layer to the edge of the polishing layer, the first groove being a centrally symmetrical double spiral structure, the width of the first groove being D1, 1 mm < D1 ≤ 3 mm, and the depth of the first groove being H1, 1 mm ≤ H1 ≤ 2 mm; A second groove is located on the surface of the polishing layer, the second groove radially extends from the center of the polishing layer to the edge of the polishing layer, the width of the second groove is D2, D2=D1, and the depth of the second groove is H2, H2=H1+c, 0.51mm≤c≤0.21mm; A third groove is located on the surface of the polishing layer. The third groove extends from a point on the second groove to the edge of the polishing layer. The width of the third groove is D3, D3=D2. The depth of the third groove is H3, H3=H2. The acute angle between the third groove and the second groove is α, and α is 30°, 45° or 60°.

2. The polishing pad according to claim 1, characterized in that The radial spacing of the first grooves is L1. Wherein 1≤a≤15, θ is the angle between a straight line connecting any point of the first groove to the center of the circle and the horizontal direction, 0≤θ≤nΠ, and n is an integer.

3. The polishing pad according to claim 1, characterized in that There are a plurality of the second grooves, and the plurality of the second grooves are evenly distributed along the circumference of the polishing layer.

4. The polishing pad according to claim 1, characterized in that There are a plurality of the third grooves, and the plurality of the third grooves are evenly distributed along the second groove.

5. The polishing pad according to claim 1, characterized in that The second groove and the third groove are both in a straight line shape or in a curved line shape.

6. The polishing pad according to claim 1, characterized in that The shape of the middle area of ​​the second groove and / or the third groove is a sine function shape.

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