CN115056137A

CN115056137A - Polishing pad with grinding consistency end point detection window and application thereof

Info

Publication number: CN115056137A
Application number: CN202210696735.7A
Authority: CN
Inventors: 谢毓; 王凯
Original assignee: Wanhua Chemical Group Electronic Materials Co ltd
Current assignee: Wanhua Chemical Group Electronic Materials Co ltd
Priority date: 2022-06-20
Filing date: 2022-06-20
Publication date: 2022-09-16

Abstract

The invention discloses a polishing pad with a grinding consistency end point detection window and application thereof, wherein the polishing pad comprises a polishing layer with a polishing surface, the surface of the polishing layer is provided with the end point detection window and three different forms of groove structures, and a first groove is a concentric circular circumferential groove on the surface of the polishing layer; the second groove is a closed ring-shaped groove surrounding the window; the third trench is a discontinuous trench distributed between the end-point detection window and the second trench. The polishing pad can avoid the grinding inconsistency caused by the detection window in the polishing process, and greatly reduce the scratch and the non-uniformity ratio.

Description

Polishing pad with grinding consistency end point detection window and application thereof

Technical Field

The invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a chemical mechanical polishing pad with an end point detection window and a special groove form.

Background

Chemical Mechanical Polishing (CMP) is the only ultra-precision processing technology capable of realizing nanoscale global Planarization in the processing and sealing process of semiconductors and micro-electro-Mechanical systems at present, is an enabling process of advanced lithography technology and copper wire technology, is a key step in the manufacturing of integrated circuits such as chips, has very important influence on the performance and power consumption of the chips, and is an essential process link for realizing advanced processing.

During polishing, the polishing endpoint is often detected in situ using an endpoint detection system to determine when a desired degree of planarization is achieved. The in-situ detection method involves a polishing pad having a transparent endpoint detection window that provides access to allow inspection of the wafer surface by a laser during polishing. However, since the inconsistency between the endpoint detection window and the polishing layer often leads to the problem of window protrusion during polishing, those skilled in the art have made many studies to ensure the consistency of polishing performance.

CN201110024951.9 discloses a creep-resistant polishing pad window, which improves the degree of system cross-linking by adjusting the type selection of prepolymer raw materials in the formula, thereby changing the creep resistance of the window, and the strain changing along with time can enable the window to be used in the polishing process without causing excessive deformation.

CN201810343549.9 discloses an aliphatic polyurethane optical end-point detection window, the end-point detection window material of the present invention has a well defined glass transition temperature (Tg) such that it can be cut, cut or shaped just above or at said Tg without deforming the end-point detection window material.

CN200880102761.0 discloses a polishing pad having a surface with a plurality of grooves of measurable depth and a barrier region without grooves; and a transparent window disposed within and surrounded by the barrier region. The presence of a barrier region that does not have a groove and surrounds the transparent window will reduce the amount of polishing composition remaining on or in the transparent window.

Since the chemical composition of the endpoint detection window and the polishing layer are not exactly the same, differences in polishing rate and polishing planarity will tend to occur during polishing. The conventional solution is to adjust the formula of the detection window to match the polishing performance of the polishing layer as much as possible, but it is also a question to be studied whether the transmittance of the detection window will be affected by the change of the formula of the detection window.

Disclosure of Invention

An object of the present invention is to provide a chemical mechanical polishing pad with an end-point detection window and a specific groove structure, which can ensure similar polishing performance between a polishing layer and the window and higher consistency of a polished product during a polishing process using the polishing pad.

It is another object of the present invention to provide the use of such a high polishing uniformity chemical mechanical polishing pad with an endpoint detection window.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

a polishing pad with a grinding consistency end point detection window comprises a polishing layer with a polishing surface, wherein the surface of the polishing layer comprises the end point detection window and grooves in three different forms, wherein the first groove is a concentric circumferential groove positioned on the surface of the polishing layer; the second groove is a closed ring-shaped groove surrounding the periphery of the endpoint detection window; the third trench is a discontinuous trench distributed between the end-point detection window and the second trench.

In a specific embodiment, the first trench and the second trench intersect at the periphery of the endpoint detection window, and the second trench and the third trench do not intersect with each other.

In a specific embodiment, the depths of the grooves of the three different forms are constant, wherein the depths of the first groove and the second groove are the same, and the depth of the third groove is greater than or equal to the depths of the first groove and the second groove.

In a specific embodiment, the first trench has a shape of concentric circles, concentric squares, concentric polygons, preferably concentric circles.

In a specific embodiment, the second trench shape is the same shape as the end-point detection window but is scaled up equally.

In a specific embodiment, the endpoint detection window has a width W1 and a length L1, and the second trench closed loop has a width W2 and a length L2; wherein the value range of W1 is 15-25 mm, preferably 18-23 mm, and the value range of L1 is 20-50 mm, preferably 25-45 mm; w2 is more than W1 and less than or equal to 3W 1; l1 is more than L2 and less than or equal to 1.5L 1.

In a specific embodiment, the second groove and the end point detection window covered by the second groove are symmetrically distributed along the length direction and the width direction.

In a specific embodiment, the third trenches are separated from each other and the third trenches are not in communication with the second trenches, the endpoint detection window; preferably, the third grooves are a plurality of uniformly distributed holes with a circular, elliptical or polygonal shape, preferably circular holes or regular polygonal holes; more preferably, the pore size of the third trenches is uniform with a maximum value less than min { (W2-W1)/2, (L1-L2)/2 }.

In a specific embodiment, the endpoint detection window is an integral or plug-in endpoint detection window.

On the other hand, the polishing pad is preferably used for chemical mechanical planarization of copper wafers, sapphire wafers, silicon wafers and wafers.

Compared with the prior art, the polishing pad with the end point detection window has the following beneficial effects:

in order to ensure uniformity of polishing, it is generally required that the end-point detection window and the surface of the polishing layer have substantially the same polishing performance. However, the endpoint detection window and polishing layer formulation and process nuances make them unable to achieve consistent polishing performance. The end-point detection window has little porosity, resulting in a window with a slightly lower compressibility, a slightly higher hardness than the polishing layer, and a surface with little ability to store slurry due to its little porosity.

The polishing pad of the invention is provided with a conventional first groove on the surface of a polishing layer, and is also provided with a closed ring-shaped second groove on the periphery of an end point detection window, so that the polishing liquid flowing through the area near the end point detection window is partially cut off in the second groove, the flow of the polishing liquid on the surface of the detection window is reduced and is lower than that of the polishing layer area without the detection window, thus the chemical and mechanical polishing effects of the two areas can be balanced, and the grinding performance of the two areas is consistent to the maximum extent; meanwhile, the third groove is configured, the content of the polishing solution is increased in the detection window area, the necessary polishing solution can be obtained in the detection window area, and the possibility that the scratch is increased due to overlarge mechanical action in the polishing process caused by the flowing of the polishing solution in the detection window area due to the overlarge obstruction of the second groove is avoided.

Drawings

FIG. 1 is a schematic top view of a polishing pad of the invention.

FIG. 2 is a schematic view of a second trench and an endpoint detection window enclosed by the second trench according to the present invention.

Wherein, 1 is a polishing layer of the polishing pad, 2 is an end point detection window, 3 is a first groove, 4 is a second groove, and 5 is a third groove.

Detailed Description

The following examples will further illustrate the method provided by the present invention in order to better understand the technical solution of the present invention, but the present invention is not limited to the listed examples, and should also include any other known modifications within the scope of the claims of the present invention.

As shown in FIG. 1, the chemical mechanical polishing pad with an endpoint detection window of grinding consistency of the invention at least comprises a polishing layer 1 with a polishing surface, wherein the surface of the polishing layer 1 is provided with an endpoint detection window 2 and grooves with three different forms. Wherein, the first groove 3 is a concentric circumferential groove on the surface of the polishing layer; the second groove 4 is a closed ring-shaped groove surrounding the periphery of the end point detection window 2; the third trench 5 is a discontinuous trench distributed between the end point detection window and the second trench.

The polishing layer of the polishing pad of the present invention may be made of any material commonly used in the art, without any limitation, and for example, the material of the polishing layer is at least one selected from a segmented block copolymer and a polyurethane elastomer, and preferably is a polyurethane elastomer. In particular, the polishing layer can be prepared by methods known in the art and well known to those skilled in the art. The polishing layer can be, for example, one or more layers of a structure without limitation. The polishing pad may also include, for example, an intermediate layer, an adhesive layer, as is also well known to those skilled in the art.

The first groove and the second groove are intersected at the periphery of the end point detection window, and the second groove and the third groove are not in contact with each other. The depth of the three types of grooves is constant, wherein the depth of the first groove is the same as that of the second groove, and the depth of the grooves is selected from 0.6-1.4 mm, preferably 0.7-1.2 mm. The depth of the third groove is greater than or equal to the depth of the first and second grooves, and the third groove is preferably a through hole structure penetrating through the polishing layer.

Specifically, the first groove is circumferentially concentric, and can be selected from a concentric circle shape and a concentric regular polygon shape, and is preferably a concentric circle shape. The first trench intersecting the second trench is cut at the intersection with the second trench, and does not penetrate through the detection window, as shown in fig. 1; and the portion of the first groove that does not intersect the second groove has a concentric circular shape.

The second groove is a complete closed loop and covers the end point detection window, the overall shape of the second groove is the same as that of the end point detection window and is amplified in equal proportion, and the second groove and the end point detection window covered by the second groove are in a symmetrical pattern along the length direction and the width direction. As shown in FIG. 2, the end point detection window has a width W1 and a length L1. The value range of W1 is 15-25 mm, preferably 18-23 mm, and the value range of L1 is 20-50 mm, preferably 25-45 mm. The second trench closed loop has a width W2 and a length L2. Wherein W2 is more than W1 and less than or equal to 3W 1; l1 is more than L2 and less than or equal to 1.5L 1.

The third grooves are discontinuously distributed between the end point detection windows and the second grooves, the third grooves are separated from each other, and the third grooves are not contacted with the second grooves and the end point detection windows. In particular, the third groove may be a hole of any shape, preferably a circular, regular polygonal hole, which is evenly distributed between the end point detection window and the second groove and does not communicate with each other. The pore size of the third grooves is uniform, and the maximum value is less than min { (W2-W1)/2, (L1-L2)/2 }.

The endpoint detection window of the present invention can be any symmetrical pattern such as, but not limited to, rectangular, oval, polygonal, preferably rectangular.

The endpoint detection window may be an inset window or a monolithic window or disposed within the polishing pad by any means known in the art.

It is understood that the polishing pad surface of the present invention may be provided with any of the above-mentioned three grooves, and the grooves may have any of the shapes of the grooves such as the form of superimposed perforations, radial shapes, etc., which is also within the scope of the present invention.

The polishing pad having an endpoint detection window of the present invention can be used for polishing at least one of a magnetic substrate, an optical substrate and a semiconductor substrate. The specific polishing method adopts the polishing pad with the grinding consistency endpoint detection window, and other polishing processes and polishing solutions can refer to the prior art, and the invention has no limitation.

The invention is further illustrated, but not limited, by the following more specific examples.

Not specifically described, the polishing pads of the examples and comparative examples of the present invention were prepared by the following methods:

and mixing the prepolymer (Chemtura, LGF 740D) and a curing agent 4, 4' -methylene-di-o-chloroaniline (alatin), stirring for reaction, and pouring to obtain a polyurethane block. A hole was punched in the block and a window block obtained by reacting a prepolymer (Chemtura, LGF 740D) with a curing agent 4, 4' -methylene-bis- (3-chloro-2, 6-diethylaniline) (alatin) was bonded into the block hole using Primer94 glue (3M). The obtained block was sliced to obtain a polishing layer sheet. And (4) attaching the polishing pad with SUBA IV (DOW) to obtain the polishing pad.

The obtained polishing pad was grooved according to the groove data of the examples and comparative examples to obtain a final surface grooved polishing pad.

The main raw materials used in the examples and comparative examples of the present invention were as follows:

equipment: mirra ^TM CMP polisher.

And (3) planarization testing: before and after each polishing experiment, the substrate was polished using a Four-point probe (Four Dimensions, Inc,

) The tester measures the thicknesses of 81 test points at the same position on the sheet, and calculates the removal rate RR from the thickness difference. The removal rate calculation formula is as follows:

wherein the content of the first and second substances,

the average of the thicknesses of 81 test points before polishing,

the average value of the thicknesses of 81 test points after polishing, delta T _avg The average value of the thickness difference before and after polishing was obtained for each of the 81 points before and after polishing. The standard deviation of the removal rate was calculated to give a non-uniformity ratio (% NUR). The smaller the non-uniformity ratio, the higher the polishing planarization degree over the entire polishing surface.

The polishing method comprises the following steps: a Cu target was polished using an ILD3225 polishing slurry (DOW) at a head pressure of 1.5psi (10.3 kPa). Polished for one minute and diamond conditioner dressed for one minute. The platen speed was 93rpm and the wafer holder head speed was 87rpm during polishing.

Scratch test: scratching of the target during polishing was expressed by the number of scratches with a target surface length of more than 5 μm.

Example 1

The polishing pad groove structure of the invention has the following specific information:

the first groove is in a concentric circle shape;

the detection window is rectangular, W1 is 18mm, and L1 is 30 mm;

the depth of the first groove and the second groove is 0.7mm, and the depth of the third groove is 1.2 mm;

the second groove W2 is 22mm, and L1 is 36.7 mm;

the third groove is circular in shape, and the aperture is 0.8 mm.

Example 2

the first groove is in a concentric circle shape;

the detection window is rectangular, wherein W1 is 20mm, and L1 is 35 mm;

the depth of the first groove and the second groove is 0.9mm, the depth of the third groove is 2.0mm, and the third groove is a through hole;

the second groove W2 is 30mm, and L1 is 52 mm;

the third groove is circular in shape, and the aperture is 1.2 mm.

Example 3

the first groove is in a concentric regular octagon shape;

the detection window is rectangular, W1 is 23mm, and L1 is 45 mm;

the depth of the first groove and the second groove is 1.1mm, the depth of the third groove is 2.0mm, and the third groove is a through hole;

the second groove W2 is 43mm, and L1 is 84 mm;

the third groove is triangular, and the aperture is 1.2 mm.

Comparative example 1

the first groove is in a concentric circle shape;

the detection window is rectangular, W1 is 18mm, and L1 is 30 mm;

the depth of the first groove and the second groove is 0.7 mm;

the second groove W2 is 22mm, and L1 is 36.7 mm;

in comparison with embodiment 1, the present comparative example does not have the third trench.

Comparative example 2

the first groove is in a concentric circle shape;

the detection window is rectangular, W1 is 18mm, L1 is 30 mm;

the depth of the first groove is 0.7mm, and the depth of the third groove is 1.2 mm;

the third groove is in a circular shape, and the aperture is 0.8 mm;

in comparison with embodiment 1, the present comparative example does not have the second groove.

Comparative example 3

the first groove is in a concentric circle shape;

the detection window is rectangular, W1 is 18mm, L1 is 30 mm;

the second groove W2 is 60mm, and L1 is 100 mm;

the third groove is circular in shape, and the aperture is 0.8 mm.

Table 1 shows scratch test data obtained by the test of examples and comparative examples.

TABLE 1 polishing test results data sheet

As can be seen from Table 1, the polishing pads constructed according to the present invention have significant advantages in polishing test pieces, both in terms of the number of scratches and the non-uniform ratio, during the polishing process of the examples.

In comparative example 1, the third groove is not provided, so that the detection window area has no good polishing solution distribution, and the scratch carding is increased; in comparative example 2, the absence of the second grooves results in a small difference in the flow rates of the polishing liquid flowing through the detection window region and the polishing layer region without the detection window, resulting in a decrease in the non-uniform ratio; the second trench-closed detection window area in comparative example 3 is too large, resulting in a large area of the polishing layer area not being able to contact sufficient polishing liquid, resulting in poor performance of both scratch performance and non-uniformity ratio.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.

Claims

1. A polishing pad with a grinding consistency end point detection window comprises a polishing layer with a polishing surface, and is characterized in that the surface of the polishing layer comprises the end point detection window and grooves in three different forms, wherein a first groove is a concentric circumferential groove positioned on the surface of the polishing layer; the second groove is a closed ring-shaped groove surrounding the periphery of the endpoint detection window; the third trench is a discontinuous trench distributed between the end-point detection window and the second trench.

2. The polishing pad of claim 1, wherein the first groove intersects the second groove at a periphery of the endpoint detection window, the second groove and the third groove not intersecting each other.

3. The polishing pad according to claim 1 or 2, wherein the depth of the grooves of the three different forms is constant, wherein the depth of the first grooves is the same as that of the second grooves, and the depth of the grooves is selected from 0.6 to 1.4mm, preferably 0.7 to 1.2 mm; the depth of the third groove is larger than or equal to the depth of the first groove and the second groove.

4. The polishing pad according to claim 1 or 2, wherein the first grooves have a shape of concentric circles, concentric squares, concentric polygons, preferably concentric circles.

5. The polishing pad of claim 1 or 2, wherein the second groove shape is the same shape as the endpoint detection window but is enlarged on an equal scale.

6. The polishing pad of claim 1 or 2, wherein the endpoint detection window has a width W1 and a length L1, and the second closed trench loop has a width W2 and a length L2; wherein the value range of W1 is 15-25 mm, preferably 18-23 mm, and the value range of L1 is 20-50 mm, preferably 25-45 mm. W2 is more than W1 and less than or equal to 3W 1; l1 is more than L2 and less than or equal to 1.5L 1.

7. The polishing pad of claim 1 or 2, wherein the second grooves and the end-point detection window covered by the second grooves are symmetrically distributed along the length and width directions.

8. The polishing pad of claim 1 or 2, wherein the third grooves are separated from each other and the third grooves are not in communication with the second grooves and the endpoint detection window; preferably, the third grooves are a plurality of uniformly distributed holes with a circular, elliptical or polygonal shape, preferably circular holes or regular polygonal holes; more preferably, the third trench pore size is uniform with a maximum less than min { (W2-W1)/2, (L1-L2)/2 }.

9. The polishing pad of claim 1 or 2, wherein the endpoint detection window is an integral or inset endpoint detection window.

10. Use of the polishing pad of any one of claims 1-9 for chemical mechanical planarization, preferably for chemical mechanical polishing of copper wafers, sapphire wafers, silicon wafers, wafers.