CN116749076A - Detection window, polishing pad and polishing system - Google Patents

Abstract

The present application relates to a detection window, a chemical mechanical polishing pad, and a polishing system. The detection window comprises a polyurethane substrate with a certain pore structure, the detection window is used for detecting a polishing end point when being applied to planarization treatment of a wafer in chemical mechanical polishing, and the filler can enable the light transmittance of the detection window to be stable in the whole service life, so that false grabbing caused by fluctuation of the light transmittance is effectively avoided, the service life of a polishing pad is effectively prolonged, and the defect number is reduced.

Description

Detection window, polishing pad and polishing system

Technical Field

The application relates to the technical field of polishing of chemical mechanical planarization treatment, in particular to a detection window, a chemical mechanical polishing pad and a polishing system.

Background

In a typical CMP process, the wafer is mounted upside down on a carrier (carrier) of a CMP tool, with the force pushing the carrier and wafer downward toward the polishing pad. The carrier and wafer rotate over a rotating polishing pad on a CMP tool polishing table, the wafer and polishing pad can rotate in the same direction or in opposite directions, and the layers of material to be removed are abraded. One commonly used method for determining the polishing endpoint is a laser detection method, and the working principle of the method is to emit a laser to a polished layer of a wafer; the wafer reflects the laser; determining whether a polishing endpoint is reached by analyzing a change in a light intensity signal of reflected light reflected by the wafer; the method requires the existence of a light-transmitting detection window on the polishing pad. In the practical application process, the reflected light intensity can be influenced by the light intensity absorbed by the detection window and the reflected light intensity of the detection window; since one wafer consumes a very small amount of the detection window, the light intensity absorbed by the detection window itself is basically unchanged in the process of grinding the same wafer. Therefore, ensuring that the detection window obtains stable reflected light intensity is one of the main schemes for ensuring accurate grasping of the grinding endpoint.

Aiming at the problems, the method commonly used in the prior art is to set a correction parameter through a system, and eliminate the influence of the change of the reflected light intensity of the detection window through the correction parameter; however, the method is mainly based on empirical adjustment, and when any grinding condition changes, correction parameters need to be reset, so that uncertainty exists; when specific conditions occur, the wafer is easy to discard; for example, when the trimmer is passivated in the later period of life, the trimmer cannot trim the detection window well, and the reflected light of the detection window suddenly decreases, which is easy to cause misjudgment of the polishing end point.

Disclosure of Invention

In order to solve the problem that the change of window reflection light intensity is continuously changed along with the grinding time and the grinding condition in the existing polishing technology. Compared with the method in the prior art, the filler is added into the polishing pad detection window substrate, and the addition of the filler is controlled to maintain the stable rough structure of the surface of the detection window in the grinding process, stabilize the reflection light intensity of the window, maintain a certain intensity transmittance of the window and ensure stable grabbing of the grinding end point.

The first aspect of the present application provides a detection window, which is disposed in a polishing layer, the detection window comprising a polymer substrate having a pore structure, the pore structure being obtained by introducing a filler into the polymer substrate, the filler being uniformly dispersed in the polymer substrate, the filler comprising one or more combinations of air or a hollow substance or a substance that is liable to form pores during polishing, the light transmittance of the detection window being between 20% and 100%, the initial roughness of the detection window being between 1 μm and 5 μm;

further, the ratio of the volume of the filler to the volume of the polymer substrate is between 0.005% and 0.78%;

preferably, the ratio of the volume of the filler to the volume of the polymer substrate is between 0.01% and 0.46%;

further, the diameter of the filler is between 0.01 and 200 mu m;

preferably, the diameter of the filler is between 0.01 and 100 mu m;

further, the roughness of the detection window is changed between 0.8 and 2.5 mu m in the polishing process;

preferably, the roughness of the detection window is between 0.8 and 2.4 mu m in the polishing process;

further, the polymer substrate comprises one or more of polyurethane, polyester, nylon, acryl, epoxy, silicone, polycarbonate;

further, the polymer substrate is polyurethane, and the polyurethane is obtained by reacting polyfunctional isocyanate, polyalcohol and curing agent;

further, the polyfunctional isocyanate comprises one or more combinations of 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 2 '-diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, 4 '-diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, ethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 1, 6-hexamethylene diisocyanate, 1, 4-cyclohexane diisocyanate, 4' -dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate;

further, the polyol comprises one or more combinations of polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol, ethylene glycol, 1, 3-butanediol, 1, 4-butanediol, diethylene glycol, neopentyl glycol, 2-methyl-1, 3-propanediol, hexanediol, 3-methyl-1, 5-pentanediol, 1, 4-cyclohexanedimethanol.

In a second aspect, the application provides a chemical mechanical polishing pad comprising the detection window described above.

A third aspect of the present application provides a polishing system comprising the chemical mechanical polishing pad described above, the polishing system further comprising a platen and a detection device, the polishing system being for polishing a wafer.

Advantageous effects

Compared with the prior art, the application has the following beneficial effects: the detection window provided by the application contains a certain amount of filler, so that the surface of the detection window has certain initial roughness and initial light transmittance, the surface roughness of the detection window is maintained to be stable in the grinding process, the reflected light intensity of the detection window is stabilized, the detection window is maintained to have certain intensity transmittance, and the stable grabbing of the grinding end point is ensured.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view showing a polishing operation performed on a polishing pad according to an embodiment of the present application;

1-a material to be polished; 2-a polishing pad; 3-a polishing machine table; 4-a bracket; 5-polishing solution.

Detailed Description

Embodiments of the present application will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

< detection Window >

The embodiment of the application provides a detection window in an arranged polishing pad, wherein the detection window comprises a polymer substrate with a certain pore structure, the pore structure is obtained by introducing a filler into the polymer substrate, wherein the filler is uniformly dispersed in the polymer substrate, and the filler comprises one or more of air or hollow substances or substances which are easy to form pores in the polishing process.

The polymer substrate in the embodiment of the application is one or a combination of more of polyurethane, polyester, nylon, acrylic, epoxy resin, silicone and polycarbonate.

Preferably, the polymeric substrate in embodiments of the present application is selected from polyurethanes.

The polyurethane used in the examples of the present application is not particularly limited, and commercially available polyurethane materials known in the art may be selected, or synthetic methods known in the art may be selected for synthesis, and as examples of synthetic methods, a prepolymer method and a one-step synthesis method may be selected; for the comprehensive performance of the window, the prepolymer method is preferably selected as the synthesis method; the prepolymer method is a common method for producing polyurethane by reacting a prepolymer with a curing agent, and for the selection of the prepolymer, polyfunctional isocyanate may be used, and the polyol may be obtained by reacting, or a commercially available prepolymer may be selected.

The polyfunctional isocyanate in the embodiments of the present application is not particularly limited, and compounds known in the art including but not limited to aromatic isocyanates and/or aliphatic isocyanates may be used, and as examples of the aromatic isocyanates, one or more of 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 2' -diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, 4' -diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate may be selected; as examples of aliphatic isocyanates, one or more combinations of ethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 1, 6-hexamethylene diisocyanate, 1, 4-cyclohexane diisocyanate, 4' -dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate may be selected.

The polyol in the embodiments of the present application is not particularly limited, and may be selected from compounds known in the art, including but not limited to one or more combinations of high molecular weight polyols or small molecular weight polyols, and as examples of high molecular weight and/or small molecular weight polyols, one or more combinations of polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol, ethylene glycol, 1, 3-butanediol, 1, 4-butanediol, diethylene glycol, neopentyl glycol, 2-methyl-1, 3-propanediol, hexanediol, 3-methyl-1, 5-pentanediol, 1, 4-cyclohexanedimethanol may be selected.

For the prepolymer in the embodiments of the present application, a commercially available prepolymer may also be selected, and preferably, one or more combinations of L325, LF750 and LF700D of Adiprene may be selected for the prepolymer.

The curing agent in the embodiments of the present application is not particularly limited and may be selected from compounds known in the art including, but not limited to, one or more of polyols, polyamines, or alcohol amines, wherein the polyamines are diamines and other polyfunctional amines. Preferably, the curing agent comprises one or more combinations of 4,4 '-methylene-bis-o-chloroaniline, 4' -methylenebis (3-chloro-2, 6-diethylaniline), dimethylthiotoluenediamine, 1, 3-propanediol di-p-aminobenzoate, diethyltoluenediamine, 5-t-amyl-2, 4-and 3-t-amyl-2, 6-toluenediamine and chlorotoluenediamine, and more preferably, the curing agent comprises one or a combination of two of 4,4 '-methylene-bis-o-chloroaniline or 4,4' -methylenebis (3-chloro-2, 6-diethylaniline).

The filler in the embodiment of the application comprises one or more of air or hollow substances or substances which are easy to form pores in the polishing process.

The pore structure of the detection window in the embodiment of the application can be realized by introducing air into the polyurethane substrate as a filler, and the method for introducing air can be selected from methods known in the art, and as an example, a method for introducing air by using a mechanical stirring method can be used.

In the embodiment of the application, after a certain amount of prepolymer, a certain amount of foaming agent and a certain amount of curing agent are dissolved, air is introduced into the mixed liquid in a mechanical stirring mode, the quantity and the size of bubbles are adjusted by controlling the addition amount of the foaming agent and the rotating speed of mechanical stirring, after the mixture is mixed for a certain time, the mixed liquid is introduced into a mold for curing process before being viscous, and then the mixed liquid is cut into a window shape which is conventional in the field, so that a detection window with a pore structure can be obtained.

On the other hand, the pore structure of the detection window in the embodiment of the present application may be achieved by introducing a hollow substance as a filler into the polyurethane substrate, and the hollow substance may be a hollow substance known in the art, and as an example of the hollow substance, a hollow microsphere polymer may be selected, wherein the hollow microsphere polymer is an expandable hollow polymer microsphere, and may be moderately expanded by a temperature increase caused by exothermic reaction during the curing process.

The adjustment of the performance of the detection window can be realized by adjusting the distribution mode and the content of the hollow microsphere polymer in the polyurethane substrate; wherein the hollow microsphere polymer comprises, but is not limited to, a capsule structure with outer walls of polyacrylonitrile and polyacrylonitrile copolymer, and can be selected from microspheres or microbeads of any one of Achilles 'oil pharmaceutical Co., ltd., preferably, the hollow microsphere polymer can be selected from Expancel series microspheres or Sorbon F series microspheres of Achilles' oil pharmaceutical Co., akzo Nobel;

alternatively, embodiments of the present application preferably use microsphere fractionation techniques to obtain hollow microsphere polymers of different particle size distributions.

On the other hand, the pore structure of the detection window in the embodiment of the present application may be achieved by introducing a substance that is easy to form pores into the polyurethane substrate as a filler, and as an example of the substance that is easy to form pores, a substance that can react with water quickly or can dissolve in water quickly during polishing to form pores, including but not limited to one or more combinations of polyacrylamide, polyglycolic acid, and polycaprolactone, preferably, one or two combinations of polyacrylamide and polyvinyl alcohol are selected.

As a method for introducing the hollow substance and/or the substance which is liable to form the pores into the polyurethane substrate in the embodiment of the present application, a method known in the art may be selected for implementation, and as an example of the method: and mixing a certain amount of prepolymer, hollow substances and/or substances easy to form pores and a curing agent for a certain time, introducing the mixture into a grinding tool for curing before the mixture is viscous, and cutting into a window shape conventional in the field to obtain the detection window with a pore structure.

In the embodiment of the application, the light transmittance of the detection window is between 20 and 100 percent, the initial roughness of the detection window is between 1 and 5 mu m, and in consideration of the sufficient light passing through the detection window and the roughness stabilizing amount, the light transmittance of the detection window is between 20 and 30 percent, and the initial roughness of the detection window is between 1 and 4 mu m.

The pore structure contained in the detection window is introduced by the filler, so that the volume of the pore structure can be modulated by controlling the volume of the filler, the detection window has lower light transmittance due to excessive pore structure (the pore structure in the polishing layer generally accounts for about 5-60% of the volume of the polishing layer in the field), and the detection window cannot show proper roughness due to excessive pore structure; the ratio of the volume of the filler to the volume of the polymer substrate is between 0.005% and 0.78%, preferably between 0.01% and 0.46%, in view of the roughness of the detection window, the light transmittance and the overall performance of the detection window.

In the embodiment of the application, the diameter of the filling material is between 0.01 and 200 mu m, and preferably between 0.01 and 100 mu m, in order to obtain the detection window with proper density and roughness.

In the embodiment of the application, in order to maintain the surface roughness stability of the detection window and the reflection light intensity stability of the detection window in the grinding process, the roughness change of the detection window in the polishing process is between 0.8 and 2.5 mu m, and preferably, the roughness change of the detection window in the polishing process is between 0.8 and 2.4 mu m.

< polishing pad >

In the embodiment of the application, the polishing pad comprises a polishing layer and a buffer layer, wherein the polishing layer can be made of materials conventionally used in the field, for example, polyurethane, and the polyurethane can obtain better polishing effect. Preferably, the polyurethane is prepared by reacting a prepolymer obtained by reacting an isocyanate with a polyol with a mixture of a curing agent and a hollow microsphere polymer.

The isocyanate, polyol, curing agent and hollow microsphere polymer involved in polyurethane in the polishing layer in the embodiment of the application are the same as or different from the above-mentioned raw materials involved in the detection window.

The buffer layer in the embodiment of the application can be one of coating gum dipping or foaming resin of non-woven fabrics which are known in the art.

The application provides a preparation method of a polishing pad, which comprises the following steps:

s1: uniformly mixing the prepolymer, filler and curing agent for preparing the detection window, and pouring, gelling, curing and cooling to obtain a detection window curing block;

s2: and uniformly mixing the prepolymer for preparing the polishing layer, the curing agent and the hollow microsphere polymer, pouring the mixture into a grinding tool containing a curing block with a detection window, obtaining the curing block of the polishing layer containing the curing block with the detection window after gelling, curing and cooling, and demolding, slicing and grooving the curing block of the polishing layer to obtain the polishing layer containing the detection window.

S3: and (3) attaching the polishing layer in the step S2 to the buffer layer to obtain the polishing pad.

The polishing pad of the present application can be used in conventional semiconductor manufacturing processes, such as, but not limited to: STI process, oxide process, W process, al process, coppers process, poly process.

< polishing System >

The polishing system of the present application: the polishing is performed using a polishing apparatus or the like as shown in fig. 1, which has a polishing table 3 supporting a polishing pad 2, a backing material for uniformly pressurizing a carrier 4 supporting a material to be polished, a semiconductor wafer 1 and the wafer, and a supply mechanism of a polishing liquid 5. The polishing pad 2 is mounted to the polishing machine table 3, for example, by adhesive backing layer. The polishing table 3 and the holder 4 are disposed so that the polishing pad 2 and the semiconductor wafer 1 supported by each are opposed to each other, and each have a rotation axis. In addition, a pressing mechanism for pressing the semiconductor wafer 1 against the polishing pad 2 is provided on the carrier 4 side. In polishing, the polishing table 3 and the holder 4 are rotated, and the semiconductor wafer 1 is pressed against the polishing pad 2, and polished while supplying slurry. The flow rate of the slurry, the polishing load, the rotation speed of the polisher table and the rotation speed of the wafer are not particularly limited, and can be appropriately adjusted.

Examples

For the convenience of understanding the present application, examples are set forth below, which should be construed as merely aiding in the understanding of the present application and are not to be construed as a particular limitation of the present application, as will be apparent to those skilled in the art.

The reference numerals in the examples are defined as follows:

TDI:2, 4-toluene diisocyanate;

PTMEG: polytetramethylene ether glycol;

MOCA:4,4' -methylene-bis- (2-chloroaniline);

the hollow microsphere polymer may be selected from:551DE40d42、461DE20d70、461DE40d60。

the raw materials are all from commercial bulk industrial products, and manufacturers comprise Basoff, korsche, wanhua chemistry, suzhou Xiangyuan, hezhou Tianci, mitsui chemistry, mitsubishi chemistry and the like.

Example 1

S1: preparation of detection window solidified block

Step (1): 100 parts by mass of an isocyanate-terminated prepolymer (the mass percent of unreacted NCO groups is 8.75-9.05%) obtained by the reaction of TDI and PTMEG was heated to 80℃and degassed under vacuum (-0.095 MPa) for 2 hours; then 0.003 mass parts of hollow microsphere polymer was added551DE40d42 as filler (hollow microsphere polymers with different particle diameters can be obtained by microsphere fractionation), uniformly dispersing the filler in the prepolymer under stirring, then degassing again under vacuum (-0.095 MPa) for 2 hours respectively, and then cooling to 50 ℃ to obtain the prepolymer containing the filler.

Step (2): adding 20 parts by mass of curing agent to cure the prepolymer obtained in the step (1); the specific operation is as follows: the prepolymer and MOCA are mixed under high-speed shearing, then casting blocks with the thickness of 12 cm are respectively formed, the blocks are gelled for 15 minutes at 70 ℃, then the blocks are heated to 100 ℃ within 30 minutes, the blocks are cured for 16 hours, the blocks are automatically cooled to room temperature in an oven after the curing is finished, a detection window curing block is obtained, and the detection window curing block is fixed in a casting mold after being demoulded.

S2: preparation of cured polishing layer blocks

Step (3): 100 parts by mass of an isocyanate-terminated prepolymer (the mass percent of unreacted NCO groups is 8.75-9.05%) obtained by the reaction of TDI and PTMEG was heated to 80℃and degassed under vacuum (-0.095 MPa) for 2 hours; then, 0.45 parts by mass of a hollow microsphere polymer was added551DE40d42, uniformly dispersing the hollow microsphere polymer in the prepolymer under stirring, then degassing again under vacuum (-0.095 MPa) for 2 hours, respectively, and then cooling to 50℃to obtain the prepolymer.

Step (4): adding 20 parts by mass of curing agent to cure the prepolymer; the specific operation is as follows: and mixing the prepolymer with MOCA under high-speed shearing, then respectively pouring the mixture into a mould containing a detection window curing block to form a detection window-containing pouring block with the thickness of 12 cm, enabling the pouring block to gel at 70 ℃ for 15 minutes, then heating the pouring block to 100 ℃ within 30 minutes, curing the pouring block for 16 hours, and automatically cooling the pouring block to room temperature in an oven after curing is completed to obtain the polishing layer curing block.

Step (5): demolding, slicing, slotting and fixing the polishing layer solidified block to prepare a polishing layer; the specific operation is as follows: the resulting cured polishing layer block was separated from the mold, cut into 2 mm thick sheets (60 sheets total), numbered sequentially from top to bottom in the range of 1 to 60, and grooved to give the polishing layer corresponding to example 1.

Example 2 the preparation process was the same as in example 1 except that step (1) was different from example 1.

The preparation method of the step (1) in the embodiment 2 comprises the following steps: 100 parts by mass of an isocyanate terminated prepolymer (the mass percent of unreacted NCO groups is 8.75-9.05%) obtained by reacting toluene diisocyanate and polytetrahydrofuran is heated to 80 ℃ and degassed under vacuum (-0.095 MPa) for 2 hours; 0.43 parts by mass of surfactant SH-192 was added, the stirrer was mounted and the rotational speed was set at 2600rpm, and after stirring for 10 minutes, the stirrer was slowly fished out.

The preparation methods of example 3 and example 4 differ in that the filler was selected from polyacrylamide and polyglycolic acid, the specific formulation is shown in table 1, and all other things are the same as in example 1.

The preparation method of comparative example 1 was different in that no filler was added, the specific formulation is shown in Table 1, and the other components were the same as in example 1.

The preparation method of comparative example 2 was different in that the particle size of the filler was different, the specific formulation is shown in Table 1, and the other components were the same as in example 1.

TABLE 1

Evaluation test method: polishing conditions for examples 1-4 and comparative examples 1-2: the polished wafer is Oxide 10K wafer, the polishing solution is polishing solution D2000E of silicon Oxide abrasive, the flow rate is 120ml/min, the trimmer is a C4 diamond disc of Saeseol, the pressure is 5lbf, the polishing head pressure is 4.5psi, the platen speed is 102rpm, the carrier speed is 108rpm, and the polishing time is 60s; specific evaluation data are shown in Table 2 and Table 3.

TABLE 2

TABLE 3 Table 3

In examples 1 to 4 and comparative examples 1 to 2, the polishing removal rate did not change much, but in comparative examples 1 to 2, the window roughness changed much in the later stage of polishing, and after polishing for a while, with passivation of the dresser, erroneous judgment of the polishing end point occurred in the detection window.

It is to be understood that variations and modifications of the above embodiments may be made by those skilled in the art in light of the above description. Therefore, the application is not limited to the specific embodiments disclosed and described above, but equivalent modifications and variations of the application should be made within the scope of the claims of the present application. Furthermore, although specific terms are used herein, such terms are used for convenience in description and are not intended to limit the application in any way.

Claims (10)

1. A detection window arranged in a polishing layer, wherein the detection window comprises a polymer substrate with a certain pore structure, the pore structure is obtained by introducing a filler into the polymer substrate, the filler is uniformly dispersed in the polymer substrate, the filler comprises one or more of air or hollow substances or substances which are easy to form pores in the polishing process, the light transmittance of the detection window is between 20 and 100 percent, and the initial roughness of the detection window is between 1 and 5 mu m.

2. The detection window according to claim 1, characterized in that the ratio of the volume of the filler to the volume of the polymer substrate is between 0.005% and 0.78%, preferably the ratio of the volume of the filler to the volume of the polymer substrate is between 0.01% and 0.46%.

3. The detection window according to claim 1, characterized in that the diameter of the filling is between 0.01 μm and 200 μm, preferably the diameter of the filling is between 0.01 μm and 100 μm.

4. The inspection window according to claim 1, characterized in that the inspection window has a roughness during polishing of between 0.8 μm and 2.5 μm, preferably between 0.8 μm and 2.4 μm.

5. The detection window of claim 1, wherein the polymeric substrate comprises one or more of polyurethane, polyester, nylon, acrylic, epoxy, silicone, polycarbonate, or a combination thereof.

6. The detection window of any one of claims 1 or 5, wherein the polymeric substrate is a polyurethane comprising a reaction of a polyfunctional isocyanate, a polyol, and a curing agent.

7. The detection window of claim 6, wherein the polyfunctional isocyanate comprises one or more of 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 2 '-diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, 4 '-diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, ethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 1, 6-hexamethylene diisocyanate, 1, 4-cyclohexane diisocyanate, 4' -dicyclohexylmethane diisocyanate, isophorone diisocyanate, and norbornane diisocyanate.

8. The detection window of claim 6, wherein the polyol comprises one or more combinations of polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol, ethylene glycol, 1, 3-butanediol, 1, 4-butanediol, diethylene glycol, neopentyl glycol, 2-methyl-1, 3-propanediol, hexanediol, 3-methyl-1, 5-pentanediol, 1, 4-cyclohexanedimethanol.

9. A chemical mechanical polishing pad comprising the detection window of any one of claims 1 to 8.

10. A polishing system comprising the chemical mechanical polishing pad of claim 9, the polishing system further comprising a platen and a detection device, the polishing system being for use in polishing a wafer.