A polishing pad endpoint inspection window and method of making and use

Abstract

The application belongs to the technical field of polishing pads, and particularly relates to a polishing pad end point inspection window and a preparation method and application thereof. The preparation method comprises the following steps: reacting aliphatic isocyanate and polyester polyol to prepare a prepolymer, mixing the prepolymer with a curing agent, vacuum defoaming, and vulcanization. The polyester polyol is polycaprolactone diol obtained by taking polycarbonate diol as a starter and modifying caprolactone. The molecular weight of the polycarbonate diol is 200-400, and the molecular weight of the polyester polyol is 1000-3000. The curing agent comprises dihydric alcohol and alicyclic polyamine. The alicyclic polyamine has a branched chain with a carbon atom number of less than or equal to 4, and the functionality of the alicyclic polyamine is greater than or equal to 2. The polishing pad end point inspection window prepared by the preparation method has high light transmittance, and the light transmittance and hardness attenuation are reduced.

Description

Technical Field

[0001] This invention belongs to the field of polishing pad technology, specifically relating to a polishing pad endpoint inspection window, its preparation method, and its application. Background Technology

[0002] In the manufacturing of integrated circuits or other electronic devices, multiple layers of conductive dielectrics, semiconductors, and dielectric materials are deposited on the wafer surface to form a thin layer. Deposition methods include physical vapor deposition (also known as sputtering, PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and electrochemical deposition (ECD). The thin layer needs to be partially or selectively removed from the wafer surface; common removal methods include wet etching and dry etching. As the stacked material layers on the wafer are deposited and removed sequentially, the top surface of the wafer becomes uneven. Since subsequent semiconductor processing (e.g., photolithography, metallization, etc.) requires a flat wafer surface, wafer planarization is necessary.

[0003] Planarization can remove unwanted surface morphologies and defects, such as rough surfaces, agglomerates, lattice damage, scratches, and contamination layers. Furthermore, in damascene processes, deposited material fills recessed areas created by patterned etching; however, the filling process cannot be perfectly precise, leading to overfilling. Therefore, it is necessary to remove material outside the recessed areas.

[0004] Chemical mechanical polishing (CMP) is commonly used in the manufacture of high-density integrated circuits to smooth the material layers deposited on the substrate and achieve global planarization. Traditional CMP technology achieves high planarization by peeling material layer by layer from the wafer surface through relative movement between the wafer and the polishing pad under pressure and in the presence of a polishing slurry. To determine when polishing is complete and to terminate the process in a timely manner, avoiding over-polishing or incomplete polishing, it is necessary to monitor the polishing endpoint during the wafer polishing process. Optical in-situ monitoring of the wafer polishing endpoint is commonly used. This technique involves a light beam passing through a window on the polishing pad to the wafer surface. After reflection, the beam passes through the window again to a detector, which analyzes the reflected beam to determine whether polishing has ended. The sensitivity and accuracy of optical in-situ monitoring depend primarily on the transmittance of the window. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to improve the light transmittance of the polishing pad window and reduce the light transmittance attenuation during the polishing process. In addition, the polishing pad window causes diffuse reflection of light due to a large number of scratches during the polishing process, which accelerates the attenuation. Controlling the hardness attenuation of the window at different temperatures can reduce the attenuation. In order to improve the light transmittance and reduce the light transmittance attenuation and hardness attenuation during the polishing process, the present invention provides a polishing pad end-point inspection window, its preparation method and application.

[0006] To this end, the present invention provides the following technical solution.

[0007] The first aspect of the present invention provides a method for preparing a polishing pad endpoint inspection window, comprising reacting aliphatic isocyanate and polyester polyol to form a prepolymer, wherein the prepolymer is mixed with a curing agent, vacuum degassing, and vulcanization;

[0008] The polyester polyol is polycaprolactone diol obtained by modifying polycarbonate diol with caprolactone; the molecular weight of the polycarbonate diol is 200-400, and the molecular weight of the polyester polyol is 1000-3000.

[0009] The curing agent comprises a diol and an alicyclic polyamine, wherein the alicyclic polyamine has branches with ≤4 carbon atoms and a functionality ≥2.

[0010] In this invention, the alicyclic polyamine has branches with ≤4 carbon atoms, including cases where the alicyclic polyamine does not have branches. For example, the branched carbon atoms of the alicyclic polyamine are 0, 1, 2, 3, or 4; the functionality of the alicyclic polyamine is 2, 3, or 4; the molecular weight of the polyester polyol is 1000, 1200, 1500, 1800, 2000, 2500, 2800, or 3000; and the molecular weight of the polycarbonate diol is 200, 240, 280, 300, 320, 340, 360, 380, or 400.

[0011] The present invention provides a polishing pad end-point inspection window with good light transmittance. During the polishing process, the light transmittance and hardness attenuation are both small, which helps to reduce scratches and diffuse reflection caused by scratches during the polishing process. The polishing pad end-point inspection window has high light transmittance, good wear resistance, and long polishing life.

[0012] In one optional embodiment, based on 100wt% of the total mass of the polishing pad endpoint inspection window, the amount of the added diol is 5-15wt%, and the amount of the added alicyclic polyamine is 10-30wt%; for example, the amount of added diol is 5wt%, 8wt%, 12wt%, 15wt%, etc.; and the amount of added alicyclic polyamine is 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, etc.

[0013] In one optional embodiment, the mass ratio of the aliphatic isocyanate to the polyester polyol is (40-55):(45-60). Exemplary examples include mass ratios of 40:60, 44:56, 50:50, and 55:45.

[0014] In one optional embodiment, the ratio of the amount of the added diol to the amount of the added alicyclic polyamine is (0.2-0.45):1. For example, the ratio of the amount of the added diol to the amount of the added alicyclic polyamine is 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, etc.

[0015] In one alternative embodiment, the alicyclic polyamine has a secondary amine component;

[0016] In one alternative embodiment, the branch is attached to a carbon atom adjacent to the secondary amine group; the branch attached to the carbon atom adjacent to the secondary amine group can provide steric hindrance, reduce reactivity, and prevent the reaction from being too fast and affecting product performance.

[0017] In one optional embodiment, the alicyclic polyamine is a diamine;

[0018] In one alternative embodiment, the diamine comprises at least one of 4,4'-methylenebis(N-sec-butylcyclohexylamine), N'-cyclohexylethane-1,2-diamine, and 4,4-bis(sec-butylamino)-dicyclohexylmethane;

[0019] In this invention, 4,4-bis(sec-butylamino)-dicyclohexylmethane (CAS No.: 15429-60-4) is a hydrogenation product of 4',4-bis-sec-butylaminodiphenylmethane with a functionality of 2; 4'-methylenebis(N-sec-butylcyclohexylamine) and N'-cyclohexylethane-1,2-diamine both have a functionality of 2.

[0020] In one optional embodiment, the diol comprises at least one selected from 1,4-butanediol, ethylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, methylpropanediol, diethylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, butyl ethylpropanediol, diethylpentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanol, neopentanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0021] In one optional embodiment, the chain extension coefficient of the curing agent is 0.9-0.98.

[0022] In one optional embodiment, the NCO content in the prepolymer is 10-18 wt%; for example, the NCO content in the prepolymer is 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, etc.

[0023] In one alternative embodiment, the aliphatic isocyanate includes at least one of 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexanedimethyl diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

[0024] In one optional embodiment, the aliphatic isocyanate is 4,4'-dicyclohexylmethane diisocyanate, the diol is 1,4-butanediol, and the diamine is 4,4'-methylenedi(N-sec-butylcyclohexylamine). Using 4'-dicyclohexylmethane diisocyanate as the aliphatic isocyanate, 1,4-butanediol as the diol, and 4,4'-methylenedi(N-sec-butylcyclohexylamine) as the diamine, the diamine possesses a secondary amine component, and the carbon atom adjacent to the secondary amine has a branched -CH3 group. This facilitates the control of the reaction rate, resulting in a window with minimal attenuation of transmittance and hardness, exhibiting optimal performance.

[0025] A second aspect of the present invention provides an endpoint inspection window for a polishing pad prepared by the above-described preparation method.

[0026] In one optional embodiment, the hardness attenuation at the end of the polishing pad inspection window is ≤10% at 65°C; for example, the hardness attenuation is 1%, 3%, 5%, 7%, 8%, etc.

[0027] In one alternative implementation, the polishing pad endpoint inspection window is applicable to a wavelength range of γ of 250-1000 nm.

[0028] In one optional embodiment, the transmittance attenuation of the polishing pad endpoint inspection window is ≤20% at wavelength γ: 400nm < γ ≤ 1000nm; for example, the transmittance attenuation is 8%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, etc.

[0029] In one optional embodiment, the transmittance attenuation of the polishing pad endpoint inspection window is ≤40% at a wavelength γ of 250nm ≤ γ ≤ 400nm. Exemplary transmittance attenuations are 20%, 28%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, etc.

[0030] A third aspect of the present invention provides a polishing pad, comprising a polishing pad top layer and a buffer layer stacked together, wherein the polishing pad end-point inspection window prepared by the above preparation method penetrates the polishing pad top layer and the buffer layer, and the total thickness h1 of the polishing pad and the thickness h2 of the polishing pad end-point inspection window satisfy: 0.2mm≤h1-h2≤0.4mm.

[0031] The technical solution of this invention has the following advantages:

[0032] 1. The present invention provides a method for preparing an endpoint inspection window for a polishing pad. This method includes reacting an aliphatic isocyanate and a polyester polyol to form a prepolymer, mixing the prepolymer with a curing agent, vacuum degassing, and vulcanization. The polyester polyol is polycaprolactone diol modified with polycarbonate diol as an initiator; the molecular weight of the polycarbonate diol is 200-400, and the molecular weight of the polyester polyol is 1000-3000. The curing agent includes a diol and an alicyclic polyamine, wherein the alicyclic polyamine has branches with ≤4 carbon atoms and a functionality ≥2. The polishing pad endpoint inspection window prepared by this method has high light transmittance and minimal light transmittance and hardness decay. The present invention uses aliphatic isocyanate as a raw material, which is more stable than existing aromatic isocyanates. The synthesized polyurethane is less prone to oxidative yellowing under ultraviolet radiation, which is beneficial for improving the light transmittance of the endpoint inspection window. This invention uses polycaprolactone diol modified with polycarbonate diol (PCDL) as an initiator. The molecular weight of PCDL is 1000-3000, which has good water resistance and abrasion resistance. This is beneficial to the stability of the polishing pad's end-point inspection window during the polishing process and to improving the polishing life of the end-point inspection window. In particular, using PCDL with a molecular weight of 200-400 as an initiator helps to impart excellent abrasion resistance and low-temperature operability to the end-point inspection window of the polishing pad. Compared with PCDL, PCDL has lower polarity. When PCDL is used as an initiator, the PCDL-modified PCDL diol is less prone to phase separation when used in combination with a curing agent, which helps to improve light transmittance. Alicyclic polyamines are beneficial for improving the light transmittance and yellowing resistance of the polishing pad's endpoint inspection window. However, due to the electron-donating effect of alicyclic polyamines, the reactivity of the amine groups is significantly affected, leading to excessively fast reaction rates and production difficulties. This invention selects alicyclic polyamines with branches containing ≤4 carbon atoms, which have suitable reactivity. Combined with a diol curing agent, this facilitates controllable exothermic reaction, longer operating time, better flexibility and elongation at break of the polishing pad's endpoint inspection window, and no obvious yellowing or other color differentiation. It also avoids the technical effects of reduced light transmittance in specific wavelengths caused by the color of the polishing pad's endpoint inspection window. The specific polyester polyol combined with the compound curing agent in this invention helps reduce light transmittance attenuation during polishing, improves wear resistance, reduces hardness attenuation, reduces scratches and diffuse reflection caused by scratches during polishing, and further reduces light transmittance attenuation.

[0033] 2. The method for preparing the polishing pad endpoint inspection window provided by the present invention, wherein the ratio of the amount of diol and alicyclic polyamine added is (0.2-0.45):1, and the chain extension coefficient of the curing agent is 0.9-0.98, which enables the polishing pad endpoint inspection window to have better light transmittance and better hardness attenuation in the range of 25-65℃. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is a front view of the polishing pad provided in an application example of the present invention;

[0036] Figure 2 This is a top view of the polishing pad provided in an application example of the present invention;

[0037] Figure label:

[0038] 1- Polishing pad top layer; 2- Buffer layer; 3- Polishing pad end point inspection window; 4- First adhesive layer; 5- Second adhesive layer; 6- Groove. Detailed Implementation

[0039] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0040] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0041] This invention provides a method for preparing a polishing pad endpoint inspection window using a prepolymer method, specifically including the following steps:

[0042] Aliphatic isocyanate and polyester polyol are reacted to form a prepolymer. The prepolymer is mixed with a curing agent, degassed under vacuum at room temperature, and cured at room temperature for 0.5-5 hours. It is then aged at 105-120℃ for 16-24 hours, sliced, and punched to obtain polyurethane, which is the end-point inspection window of the polishing pad.

[0043] Example 1

[0044] This embodiment provides a method for preparing a polishing pad endpoint inspection window, including the following steps:

[0045] 4,4'-Dicyclohexylmethane diisocyanate and polycaprolactone diol (using PCDL with a molecular weight of 320 as the initiator, modified with caprolactone, and polycaprolactone diol with a molecular weight of 1000) were mixed at a mass ratio of 45.5:54.5 to obtain a prepolymer with an NCO content of 10%. Using a polishing pad with an endpoint inspection window totaling 100 wt%, 1,4-butanediol (5.16 wt%), and 4,4'-methylenebis(N-sec-butylcyclohexylamine) (15.03 wt%), and a compound curing agent with a chain extension coefficient of 0.95, the prepolymer was mixed with the curing agent and then poured into a mold with sides of 36 cm and a height of 10 cm. After pouring, degassing was completed within 5 minutes, and the mixture was cured at room temperature for 2 hours before being transferred to a 110℃ oven for drying for 18 hours for further curing. After the curing process is complete, remove the slices, discard any unfinished slices on the surface, and then perform a 57×19mm R2 chamfering cut.

[0046] The thickness of the polishing pad end-point inspection window prepared in this embodiment is 3.3±0.05mm, the length is 57mm, and the width is 19mm.

[0047] Example 2

[0048] This embodiment provides a method for preparing a polishing pad endpoint inspection window, including the following steps:

[0049] Isophorone diisocyanate and polycaprolactone diol (using PCDL with a molecular weight of 260 as the initiator, modified with caprolactone, and polycaprolactone diol with a molecular weight of 2000) were mixed at a mass ratio of 40.9:59.1 to obtain a prepolymer with an NCO mass ratio of 13%. Using a polishing pad endpoint inspection window with a total mass of 100 wt%, 1,3-butanediol was added at 5.6 wt%, 4,4-bis(sec-butylamino)-dicyclohexylmethane at 16.8 wt%, and the curing agent had a chain extension coefficient of 0.98. The prepolymer and curing agent were mixed and then poured into a mold with sides of 36 cm and a height of 10 cm. After pouring, degassing was completed within 5 minutes, and the mixture was cured at room temperature for 2 hours before being transferred to a 110℃ oven for 18 hours of curing. After curing, the mixture was removed, sliced, and thin slices with incomplete surface layers were discarded. A 57×19 mm R2 chamfered cut was then performed. The dimensions of the polishing pad endpoint inspection window in this embodiment are the same as in Embodiment 1.

[0050] Example 3

[0051] This embodiment provides a method for preparing a polishing pad endpoint inspection window, including the following steps:

[0052] 1,4-Cyclohexanedimethyl diisocyanate and polycaprolactone diol (using PCDL with a molecular weight of 320 as the initiator, modified with caprolactone, and polycaprolactone diol with a molecular weight of 3000) were mixed at a mass ratio of 40.8:59.2 to obtain a prepolymer with an NCO mass ratio of 16%. Using a polishing pad endpoint inspection window totaling 100 wt%, 1,5-pentanediol added at 6.16 wt%, N'-cyclohexylethane-1,2-diamine added at 18.38 wt%, and a curing agent with a chain extension coefficient of 0.90, the prepolymer and curing agent were mixed and then poured into a mold with sides of 36 cm and a height of 10 cm. After pouring, degassing was completed at room temperature within 5 minutes. After curing at room temperature for 2 hours, the mixture was transferred to a 110℃ oven for drying for 18 hours for further maturation. After curing is complete, remove the product, slice it, discard any incomplete surface slices during slicing, and complete a 57×19mm R2 chamfering cut. The dimensions of the polishing pad endpoint inspection window in this embodiment are the same as in Embodiment 1.

[0053] Example 4

[0054] This embodiment provides a method for preparing a polishing pad endpoint inspection window, which is basically the same as that in Embodiment 2, except that the mass ratio of isophorone diisocyanate to polycaprolactone diol is adjusted to 52:48. The size of the polishing pad endpoint inspection window in this embodiment is the same as that in Embodiment 1.

[0055] Example 5

[0056] This embodiment provides a method for preparing a polishing pad endpoint inspection window, which is basically the same as that in Embodiment 3, except that: the total mass of the polishing pad endpoint inspection window is 100wt%, the amount of 1,5-pentanediol added is 5wt%, and the amount of N'-cyclohexylethane-1,2-diamine added is 13.78wt%. The size of the polishing pad endpoint inspection window in this embodiment is the same as that in Embodiment 1.

[0057] Comparative Example 1

[0058] This comparative example provides a method for preparing a polishing pad endpoint inspection window, which is basically the same as Example 1, except that: diethylene glycol (DEG) is used as the initiator, and polycaprolactone diol with a molecular weight of 1000 obtained by modifying caprolactone is used instead of the polycaprolactone diol in Example 1.

[0059] Comparative Example 2

[0060] This comparative example provides a method for preparing a polishing pad endpoint inspection window, which is basically the same as that in Example 1, except that the molecular weight of the polyester polyol in this comparative example is 500.

[0061] Comparative Example 3

[0062] This comparative example provides a method for preparing a polishing pad endpoint inspection window, which is basically the same as Example 1, except that the diol in the curing agent is removed.

[0063] Comparative Example 4

[0064] This comparative example provides a method for preparing a polishing pad endpoint inspection window, which is basically the same as Example 1, except that the alicyclic polyamine in the curing agent is removed.

[0065] Application examples

[0066] An application example provides a polishing pad, such as Figure 1-2 As shown, the polishing pad includes a top layer 1, a first adhesive layer 4, a buffer layer 2, and a second adhesive layer 5 stacked in sequence. The polishing pad end point inspection window 3 passes through the polishing pad top layer 1, the first adhesive layer 4, the buffer layer 2, and the second adhesive layer 5 in sequence. The total thickness h1 of the polishing pad and the thickness h2 of the polishing pad end point inspection window satisfy the following conditions: h1 = 3.7 mm, h2 = 3.3 mm.

[0067] Methods for preparing polishing pads include:

[0068] (1) Preparation of the polishing pad top layer: isocyanate prepolymer (using Lanxess) LF 750D (unreacted isocyanate NCO content 8.75-9.05 wt%), curing agent 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), and microspheres (Nouryon 461DE20d70) were prepared. The microspheres and isocyanate prepolymer were mixed and dispersed to form a dispersion. The curing agent was mixed with the dispersion at the casting machine head to form a mixture. The molar ratio of amine groups in the curing agent to unreacted NCO in the isocyanate prepolymer was 0.87. After casting, the mixture was allowed to cure on the surface and become non-flowable before being transferred to a 106°C oven for 16 hours. After curing, it was cooled to room temperature and cut into 80 mil thick slices, which became the top layer of the polishing pad.

[0069] (2) The top layer of the polishing pad is sanded and grooved to create a surface pattern in the form of concentric circles, forming several grooves 6 with a common geometric center. The gap between adjacent grooves is uniform, with a groove width of 0.5 mm and a depth of 0.7 mm. After grooving, it is bonded to the buffer layer 2 (model: SUBAIV(DOW)). A first adhesive layer 4 is provided between the top layer 1 of the polishing pad and the buffer layer 2. The buffer layer 2 is bonded to a second adhesive layer 5, which includes a PET film and a base adhesive coated on the surface of the PET film. Then, a region that penetrates the top layer and buffer layer of the polishing pad and matches the polishing pad endpoint inspection window is punched out. The polishing pad endpoint inspection window is placed in the matching region, and finally, a polishing pad with a diameter of 30.5 inches is punched out. The polishing pad endpoint inspection windows of each embodiment and comparative example are made into polishing pads according to the above method, and the polishing performance is tested.

[0070] Test case

[0071] This test case provides the performance and performance testing methods for the polishing pad endpoint inspection window prepared in each embodiment and comparative example, as detailed below:

[0072] (1) Test method for light transmittance: Refer to GB2410 2008 "Test method for light transmittance and haze of transparent plastics".

[0073] (2) Test method for hardness decay: Hardness was tested at 25℃ and 65℃ respectively, and recorded as D1 and D2 respectively. Decay variable = (D1-D2) / D1.

[0074] (3) Polishing test: Polishing object: Copper-clad monocrystalline silicon wafers were used as polishing wafers; the polishing machine was an F-REX300X 300mm chemical mechanical planarization system. The polishing slurry was CeO2 polishing slurry, the polishing pad dresser was a diamond dresser, the polishing head pressure during the initial dressing process was 210 / 215 / 219 / 226 / 229 / 226 / 259 / 281 hPa, the polishing time was 60s, the polishing disc speed was 87 rpm, the polishing head speed was 93 rpm, the polishing slurry flow rate was 300 ml / min, and the drop point was set at 36 mm.

[0075] After finishing, the polishing pad is flatly attached to the polishing disc for polishing. The polishing process is set to Ex-situ Condition, with the following parameters: polishing disc speed 70 rpm, polishing head speed 80 rpm, and polishing time 50 seconds. The window transmittance is checked at different wavelengths before and during polishing. Wavelength γ includes two bands: 250nm ≤ γ ≤ 400nm and 400nm < γ ≤ 1000nm. The maximum transmittance attenuation is calculated for each band. The maximum transmittance attenuation is the maximum value obtained at different wavelengths. Transmittance attenuation = (transmittance before polishing - transmittance after polishing) / transmittance before polishing. The transmittance before and after polishing is obtained at the same wavelength. The maximum light intensity is recorded simultaneously with the transmittance measurement.

[0076] The number of scratches on the polished surface is counted. Scratches are defined as lines with a maximum width greater than 0.5μm. The acceptable requirement is that the number of scratches is less than 10 within a 12-inch wafer.

[0077] Count the particles on the wafer surface: count the number of particles <0.1μm, particles with a diameter of 0.1-0.5μm, and particles >0.5μm respectively; acceptance requirements: the number of particles <0.1μm ≤100, the number of particles 0.1-0.5μm ≤10, and no particles >0.5μm. The number of particles on the wafer surface is obtained automatically by scanning using the integrated particulate module inside the polishing machine.

[0078] The test results are shown in the table below.

[0079] Table 1. Endpoint inspection window and performance results of the polishing pads obtained in each embodiment and comparative example.

[0080]

[0081] A polishing pad with a hardness of 60-71D is considered suitable. Too low a hardness can lead to particle residue, while too high a hardness results in a lack of toughness, causing significant residue and scratches during polishing. Comparative Examples 1-2 demonstrate that this invention uses PCDL with a molecular weight of 200-400 as an initiator, modifying it with caprolactone to obtain polycaprolactone diol with a molecular weight of 1000-3000, which can reduce hardness decay and light transmittance decay, and improve wear resistance. Comparative Examples 3-4 show that the compounded curing agent system used in this invention helps reduce light transmittance decay, improve wear resistance, and reduce scratches and diffuse reflection during polishing.

[0082] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a polishing pad endpoint inspection window, characterized in that, A prepolymer is prepared by reacting aliphatic isocyanates and polyester polyols. The prepolymer is then mixed with a curing agent, vacuum degassed, and vulcanized. The NCO content in the prepolymer is 10-18 wt%. The polyester polyol is polycaprolactone diol obtained by modifying polycarbonate diol with caprolactone; the molecular weight of the polycarbonate diol is 200-400, and the molecular weight of the polyester polyol is 1000-3000. The curing agent comprises a diol and an alicyclic polyamine, wherein the alicyclic polyamine has branches with ≤4 carbon atoms, the functionality of the alicyclic polyamine is ≥2, the alicyclic polyamine has a secondary amine group, and the branches are attached to carbon atoms adjacent to the secondary amine group. The chain extension coefficient of the curing agent is 0.9-0.

98.

2. The preparation method according to claim 1, characterized in that, Based on 100wt% of the total mass of the polishing pad endpoint inspection window, the amount of the added diol is 5-15wt%, and the amount of the added alicyclic polyamine is 10-30wt%. And / or, the mass ratio of the aliphatic isocyanate to the polyester polyol is (40-55):(45-60).

3. The preparation method according to claim 2, characterized in that, The ratio of the amount of the added diol to the amount of the added alicyclic polyamine is (0.2-0.45):

1.

4. The preparation method according to claim 1, characterized in that, The alicyclic polyamine is a diamine; And / or, the diol comprises at least one selected from 1,4-butanediol, ethylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, methylpropanediol, diethylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, butyl ethylpropanediol, diethylpentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanol, neopentanediol, 1,5-pentanediol, and 1,6-hexanediol.

5. The preparation method according to claim 4, characterized in that, The diamine includes at least one of 4,4'-methylenebis(N-sec-butylcyclohexylamine) and 4,4-bis(sec-butylamino)-dicyclohexylmethane.

6. The preparation method according to claim 1, characterized in that, The aliphatic isocyanate includes at least one of 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexanedimethyl diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

7. The preparation method according to any one of claims 1-6, characterized in that, The aliphatic isocyanate is 4,4'-dicyclohexylmethane diisocyanate, the diol is 1,4-butanediol, and the alicyclic polyamine is 4,4'-methylenedi(N-sec-butylcyclohexylamine).

8. The endpoint inspection window of the polishing pad prepared by the preparation method according to any one of claims 1-7.

9. The polishing pad endpoint inspection window according to claim 8, characterized in that, The hardness at the end-point inspection window of the polishing pad is ≤10% at 65℃; And / or, the polishing pad endpoint inspection window is applicable to a wavelength range of γ of 250-1000nm.

10. The polishing pad endpoint inspection window according to claim 9, characterized in that, The transmittance at the end-point inspection window of the polishing pad satisfies the following condition at wavelength γ: 400nm < γ ≤ 1000nm; And / or, the transmittance attenuation of the polishing pad endpoint inspection window is ≤40% at wavelength γ, where 250nm≤γ≤400nm.

11. A polishing pad, characterized in that, The polishing pad includes a top layer and a buffer layer stacked together. The polishing pad end-point inspection window prepared by the preparation method according to any one of claims 1-7 penetrates the top layer and the buffer layer of the polishing pad. The total thickness h1 of the polishing pad and the thickness h2 of the polishing pad end-point inspection window satisfy the following condition: 0.2mm≤h1-h2≤0.4mm.

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