TWI633971B - Polishing pad and preparation method thereof - Google Patents

Abstract

The invention relates to a polishing pad and a preparation method thereof, comprising two or more grooves, a polyurethane substrate, a polyurethane fiber substrate, a polyurethane rubber PSA-A layer and a polyurethane vinyl PSA-B layer, and a surface of the polyurethane substrate The groove is evenly arranged on the other surface, and the other surface is bonded to one surface of the polyurethane fiber substrate by a polyurethane rubber PSA-A layer, and the other surface of the polyurethane fiber substrate is connected to the polyurethane rubber PSA-B layer. Ultra-short polyester fiber or ultra-short aramid fiber is added to the polyurethane substrate of the invention. Polyester is an important variety in synthetic fiber and is the trade name of polyester fiber. Polyester fiber has high strength, good elasticity, good wear resistance, acid and alkali resistance, moisture absorption, and deformation, which are suitable for chemical mechanical polishing pad.

Description

Polishing pad and preparation method thereof

The invention relates to a polishing pad and a preparation method thereof, in particular to a polishing pad with a fiber-filled solid polyurethane and a preparation method thereof, and belongs to the field of precision polishing of semiconductor wafers, polishing of LED substrates, and polishing of sapphire.

The semiconductor industry is at the heart of the modern electronics industry, and the semiconductor industry is based on the materials industry. Although a variety of new semiconductor materials continue to emerge, more than 90% of semiconductor devices and circuits, especially ultra-large integrated circuits (ULSI), are fabricated on high-purity, high-quality germanium single crystal polishing wafers and epitaxial wafers. At present, ultra-large integrated circuit manufacturing technology has been developed to the 0.25nm and 300mm era. With the further miniaturization of the characteristic line width, higher requirements are placed on the degree of planarization of the surface of the cymbal. CMP is recognized as the best material global planarization method in the ULSI stage, which can obtain a perfect surface. Moreover, a higher polishing rate can be obtained, which has basically replaced the conventional heat flow method, the rotary glass method, the etch back method, the electron surround resonance method and the like.

The chemical mechanical polishing pad plays an important role in the whole polishing process. In addition to the effective uniform distribution of the polishing liquid, it can also provide a new supplementary polishing liquid, and can smoothly carry out the polishing liquid and product after the reaction. discharge. Hardness is an important parameter to characterize the performance of the polishing pad. A hard polishing pad can be used to obtain better overall and local flatness, while a soft polishing pad can achieve better surface quality and activity. The porosity and surface roughness of the polishing pad are important parameters affecting the transmission efficiency of the polishing liquid. As the use time increases, the surface of the polishing pad will become smooth, the pores will be blocked and reduced, and the polishing speed will decrease. Correct it to make it as it is. At the same time, chemical machine The effect of pressure and other mechanical forces in mechanical polishing, after polishing for a certain period of time, the polishing pad is mechanically twisted and deformed, the effect of the polishing effect caused by the problem and the shortening of the service life of the polishing pad, Rohm and Haas Company in 2000 The chemical mechanical polishing pad invented at the beginning of the year relies on the addition of other chemicals to alleviate the negative effects caused by polishing distortion. Because the chemical is elastic, the pressure resistance is above 30 MPa, it has good mechanical strength, and it has mechanical distortion. Highly resilient. However, the substance is extremely light in weight. Once the package is opened, it is easy to fly in the process of adding. When operating, it is necessary to wear protective glasses, protective tools such as hand protection and protective mask, and it is not easy to stir. In addition, the substance manufacturer is single and must rely on foreign imports. In order to solve this problem, mass production is facilitated, and the service life and mechanical properties of the polishing pad are improved.

The technical problem to be solved by the present invention is to provide a polishing pad which can be mass-produced, has improved service life and mechanical properties, and a preparation method thereof.

The technical means for solving the above technical problems are as follows: a polishing pad comprising two or more grooves, a polyurethane substrate, a polyurethane fiber substrate, a polyurethane rubber PSA-A layer, and a polyurethane vinyl PSA-B layer, a polyurethane substrate One surface is evenly arranged with grooves, and the other surface is bonded to one surface of the polyurethane fiber substrate by a urethane vinyl PSA-A layer, and the other surface of the polyurethane fiber substrate is bonded to the urethane vinyl PSA-B layer.

The beneficial effects of the invention are: the groove serves to transport the new polishing liquid, discharge the old polishing liquid and the debris generated after the grinding; the polyurethane substrate acts as a polishing; the polyurethane fiber substrate mainly serves as a buffering and heat dissipating effect; the polyurethane ethylene Glue PSA-A layer, which is used for the bonding of the upper substrate and the substrate; the PSA-B layer of the polyurethane vinyl adhesive acts as a bonding between the polishing pad and the polishing platform.

Based on the above technical means, the present invention can also be improved as follows.

Further, the shape of the polyurethane substrate, the polyurethane fiber substrate, the urethane vinyl PSA-A layer and the urethane vinyl PSA-B layer are all circular, the radius of the polyurethane substrate is smaller than the radius of the polyurethane fiber substrate, and the central region is formed without grooves. The grooved region, the grooveless region has a circular shape and has the same center as the polyurethane fiber substrate.

Further, the diameter of the polyurethane fiber substrate is from 350 mm to 1100 mm.

Further, the groove-free area is provided with a coded mark area, and the groove-free area has a diameter of 10 mm to 60 mm, and the coded mark area and the groove-free area have the same center, and the diameter thereof is 2 mm to 20 mm.

Further, the groove has a depth of 0.5 mm to 1.5 mm and a width of 0.2 mm to 1.0 mm.

Further, the thickness of the polyurethane substrate is 1.1 mm to 3.0 mm; the thickness of the polyurethane fiber substrate is 0.8 mm to 2.2 mm; the thickness of the PSA-A layer of the polyurethane rubber is 0.8 mm to 2.0 mm; and the PSA-B layer of the polyurethane rubber adhesive The thickness is from 0.8 mm to 2.0 mm.

Another technical means for solving the above technical problems is as follows: a method for preparing a polishing pad, comprising the steps of: 1) heating the prepolymer reactant to 75 ° C, heating the MOCA to 115 ° C, and then at 75 ° C to 115 The gel is carried out at a temperature of °C for a gel time of about 5 to 15 minutes, wherein the weight ratio of the prepolymer reactant to the MOCA is 3.58:1; 2) the ultrashort polyester having a weight percentage of 1% to 8% The fiber or ultrashort aramid fiber is added to the prepolymer reactant, and the prepolymer reactant is thoroughly stirred and mixed with MOCA at a rotation speed of 1500 rpm to 3500 rpm to obtain a mixture A; 3) the mixture A is placed High temperature gelation in a centrifuge at 92 ° C to 110 ° C, gel for 30 minutes to 90 minutes to obtain a gelled polyurethane sheet; 4) Transfer the gelled polyurethane sheet obtained in step 3) to a vulcanization oven Curing at a temperature of 100 ° C to 120 ° C for 10 to 17 hours to obtain a vulcanized polyurethane sheet; 5) using the vulcanized polyurethane sheet obtained in the step 4) as a polyurethane substrate, and forming the polyurethane fiber into a polyurethane fiber Substrate, by polyurethane ethylene PSA-A as glued together with adhesive, then Then, a layer of polyurethane vinyl PSA-B is further coated on the other surface of the polyurethane fiber substrate, and then stamped and formed. After molding, more than two grooves are dug on the surface of the polyurethane substrate to obtain a polishing pad.

Further, the preparation steps of the ultra-short polyester fiber or the ultra-short aramid fiber are as follows: the esterification or transesterification reaction and the polycondensation reaction are carried out by using terephthalic acid or dimethyl terephthalate and ethylene glycol as raw materials to obtain a poly Ethylene terephthalate, which is then spun and post-treated to form ultra-short polyester fiber or ultra-short aramid fiber; among them, ultra-short polyester fiber or ultra-short aramid fiber is arranged in a diameter of 0.1 μm to 15 μm. Uniform, non-polymerized powdered fiber.

Further, the prepolymer reactant is an isocyanate-terminated reaction product formed by the reaction of a prepolymer polyol and a polyfunctional aromatic isocyanate, and the isocyanate-terminated reaction product contains 7.5% to 9.9% by weight of unreacted NCO.

Further, the prepolymer polyol includes any one of polytetramethylene ether glycol, polypropylene ether glycol, ethylenedipicate or butylene glycol diacrylate.

Among them, polytetramethylene ether glycol (PTMEG) is commercially available from DuPont Terathane 2900, 2000, 1800, 1400, 1600, 650, 250 series.

Polypropylene ether glycol (PPG) is commercially available from BASF's PolyTHF 650, 1000, 1800, 2000 series and Lyondell's Polymeg 2000, 1000, 1500, 650 series.

The polyfunctional aromatic isocyanate has one or more aromatic rings and one or more isocyanate groups attached directly or indirectly to one or a different aromatic ring.

Including 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4'4-diphenylmethane diisocyanate, benzene-1,5-diisocyanate, dimethylamine diisocyanate, p-phenylene diisocyanate or Any one of xylene diisocyanate and the like.

Ultra-short polyester fiber or ultra-short aramid fiber is added to the polyurethane substrate of the invention. Polyester is an important variety in synthetic fiber and is the trade name of polyester fiber. Polyester fiber has high strength, good elasticity, good wear resistance, acid and alkali resistance, moisture absorption, and deformation, which are suitable for chemical mechanical polishing pad. The melting point of polyester fiber is usually 255 ° C to 260 ° C. Since the isocyanate-terminated polyurethane prepolymer has a temperature below 150 ° C in the whole process of synthesizing chemical mechanical polishing pad, it can be used safely in production.

Polyester fiber not only has unique physical and chemical properties, but also has a suitable specific gravity, which is easy to operate and add. It has no adverse effects on people and the surrounding environment during operation. At the same time, by studying the plasticity of polyurethane materials, adding polyurethane with proper proportion of polyester fiber can greatly increase the elasticity of polyurethane itself. The improvement of elasticity enhances the polishing pad itself resisting the deformation ability caused by mechanical extrusion, and the self-repair of the material. Ability to enhance. The polishing data proves that the global flatness of the polishing pad with ultra-short polyester fiber added in chemical mechanical polishing is significantly enhanced compared with the flatness flatness of the polishing pad without polyester.

Polyurethane polishing pad with polyester fiber added, because it has no expansion during casting process, can also be called solid hard polyurethane polishing pad, which makes the chemical mechanical polishing pad have the hardness and elasticity and mechanical properties required for trial and semiconductor wafer polishing in semiconductor wafers. The polishing of the tungsten wire layer, the polishing of the oxide layer, and the polishing of the copper show good polishing rate and flatness, resulting in higher quality surface flatness and cleanliness.

Due to the high strength and high wear resistance of polyester fiber itself, the polyurethane polishing pad with polyester fiber has a significantly longer service life than the polyurethane polishing pad without fiber. The test data shows that the polyurethane polishing with polyester fiber is added. The life of the pad is up to 70 to 75 hours in the oxide layer, which is 1.7 times the service life of the Dow IC1010 polishing pad, which is now on the market; Polyester fiber polyurethane polishing pad has a service life of up to 40 to 45 hours in the metal layer, which is 2.2 times the service life of the Dow IC1000 polishing pad.

The polishing process parameters are as follows:

1‧‧‧Polyurethane substrate

2‧‧‧Polyurethane fiber substrate

3‧‧‧ Polyurethane vinyl adhesive PSA-A layer

4‧‧‧ Polyurethane vinyl PSA-B layer

5‧‧‧ trench

6‧‧‧No groove area

7‧‧‧ Coded identification area

Figure 1 is a plan top view of a polishing pad of the present invention.

Figure 2 is a half cross-sectional view of the polishing pad of the present invention.

Figure 3 is a graph showing the service life of the polishing pad of the present invention on the 8-layer wafer oxide layer.

Figure 4 is a graph showing the service life of the polishing pad of the present invention on the 8-inch wafer metal tungsten wire layer.

The principles and features of the present invention are described below in conjunction with the drawings, which are intended to illustrate the invention and not to limit the scope of the invention.

A polishing pad, as shown in Figures 1 and 2, comprising two or more grooves 5, a polyurethane substrate 1, a polyurethane fiber substrate 2, a polyurethane rubber PSA-A layer 3, and a polyurethane vinyl PSA-B layer 4, The surface of the polyurethane substrate 1 is uniformly arranged with a groove 5 on one surface, and the other surface is bonded to a surface of the polyurethane fiber substrate 2 by a polyurethane rubber PSA-A layer 3, and the other surface of the polyurethane fiber substrate 2 is made of polyurethane ethylene. The glue PSA-B layer 4 is connected.

Polyurethane substrate 1, polyurethane fiber substrate 2, polyurethane vinyl adhesive PSA-A layer 3 and polyurethane vinyl adhesive PSA-B layer 4 have a circular shape, and the radius of the polyurethane substrate 1 is smaller than the radius of the polyurethane fiber substrate 2, and the center thereof The region forms a groove-free region 6, which has a circular shape and has the same center as the polyurethane fiber substrate 2.

The polyurethane fiber substrate 2 has a diameter of 350 mm to 1100 mm. The grooveless area 6 is provided with a coded mark area 7 having a diameter of 10 mm to 60 mm, and the coded mark area 7 has the same center as the grooveless area 6, and has a diameter of 2 mm to 20 mm.

The groove 5 has a depth of 0.5 mm to 1.5 mm and a width of 0.2 mm to 1.0 mm. The polyurethane substrate 1 has a thickness of 1.1 mm to 3.0 mm; the polyurethane fiber substrate 2 has a thickness of 0.8 mm to 2.2 mm; the polyurethane vinyl PSA-A layer 3 has a thickness of 0.8 mm to 2.0 mm; and the polyurethane vinyl PSA-B layer The thickness of 4 is from 0.8 mm to 2.0 mm.

A method for preparing a polishing pad, comprising the steps of: 1) heating the prepolymer reactant to 75 ° C, heating the MOCA to 115 ° C, and then performing the gel at a temperature of 75 ° C to 115 ° C, and the gel time is about 5 to 15 minutes, wherein the weight ratio of prepolymer reactant to MOCA is 3.58:1; 2) adding 1% to 8% by weight of ultrashort polyester fiber or ultrashort aramid fiber to the prepolymer reaction The prepolymer reactant is thoroughly stirred and mixed with MOCA at a rotational speed of 1500 rpm to 3500 rpm to obtain a mixture A; 3) the mixture A is placed in a centrifuge at 92 ° C to 110 ° C for high temperature gelation. , gel for 30 minutes to 90 minutes, to obtain a polyurethane sheet after gelation; 4) transfer the gelled polyurethane sheet obtained in step 3) to a vulcanization oven, and vulcanize at a temperature of 100 ° C to 120 ° C for 10~ 17 hours to obtain a vulcanized polyurethane sheet; 5) The vulcanized polyurethane sheet obtained in the step 4) is used as a polyurethane substrate, and the polyurethane fiber is made into a polyurethane fiber substrate, which is bonded together by a polyurethane rubber PSA-A as a backing phase, and then on a polyurethane fiber substrate. The other surface is further coated with a layer of polyurethane vinyl PSA-B, which is then stamped and formed. After molding, more than two grooves are dug on the surface of the polyurethane substrate to obtain a polishing pad.

The preparation steps of ultra-short polyester fiber or ultra-short aramid fiber are as follows: esterification or transesterification reaction and polycondensation reaction using terephthalic acid or dimethyl terephthalate and ethylene glycol as raw materials to obtain polyparaphenylene Ethylene glycol dicarboxylate, which is then spun and post-treated to form ultra-short polyester fiber or ultra-short aramid fiber; wherein ultra-short polyester fiber or ultra-short aramid fiber has a diameter of 0.1 μm to 15 μm, and the arrangement is uniform. Polymerized powdered fiber.

The prepolymer reactant is an isocyanate-terminated reaction product formed by the reaction of a prepolymer polyol and a polyfunctional aromatic isocyanate, the isocyanate-terminated reaction product comprising 7.5% to 9.9% by weight of unreacted NCO.

The prepolymer polyol includes any one of polytetramethylene ether glycol, polypropylene ether glycol, ethylene glycol diacetate or butylene glycol diacrylate; and the polyfunctional aromatic isocyanate includes 2,4- Toluene diisocyanate, 2,6-toluene diisocyanate, 4'4-diphenylmethane diisocyanate, benzene-1,5-diisocyanate, dimethylamine diisocyanate, p-phenylene diisocyanate or xylene diisocyanate Any of them.

Example 1 Test data and results of oxide polishing

1. Polishing mechanical parameter setting

Polishing results:

Polishing rate and polishing flatness:

From the above test results and Figure 3, the overall polishing rate of the polyester-polished polyurethane polishing pad can be improved by fine-tuning the polishing pressure, and the polishing flatness rate is very stable at about 2%. This flatness ratio is generally recognized on the market. A flatness value of 7% or less is greatly reduced. In chemical mechanical polishing, the lower the global polishing flatness, the better the overall polishing effect and the higher the yield of the wafer.

Example 2 Test Data and Results of Metal Layer Polishing

Polishing results:

Polishing rate and polishing flatness:

It can be seen from the above test results and Fig. 4 that no matter how the polishing test parameters are adjusted, the polishing pad is added or lowered with the change of the polishing parameters, and the polyurethane polishing pad with 0.5% to 7% of the polyester fiber powder is always added. It exhibits excellent and very smooth global flatness (NU%). And the polishing life is greatly increased.

Example 3 AF test results for polishing surface flatness:

The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalents, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims (10)

A polishing pad comprising two or more grooves, a polyurethane substrate, a polyurethane fiber substrate, a urethane vinyl PSA-A layer and a urethane vinyl PSA-B layer, the groove being evenly arranged on one surface of the polyurethane substrate The other surface of the groove is bonded to a surface of the polyurethane fiber substrate by the polyurethane vinyl PSA-A layer, and the other surface of the polyurethane fiber substrate is connected to the polyurethane vinyl PSA-B layer. The polishing pad according to claim 1, wherein the polyurethane substrate, the polyurethane fiber substrate, the urethane vinyl PSA-A layer and the urethane vinyl PSA-B layer are all round in shape, and the polyurethane The radius of the substrate is smaller than the radius of the polyurethane fiber substrate, and the central portion thereof forms a groove-free region having a circular shape and having the same center as the polyurethane fiber substrate. The polishing pad of claim 2, wherein the polyurethane fiber substrate has a diameter of from 350 mm to 1100 mm. The polishing pad of claim 3, wherein the groove-free area is provided with a coded mark area having a diameter of 10 mm to 60 mm, and the coded mark area has the same same as the groove-free area. The center of the circle, and its diameter is 2mm to 20mm. The polishing pad according to any one of claims 1 to 4, wherein the groove has a depth of 0.5 mm to 1.5 mm and a width of 0.2 mm to 1.0 mm. The polishing pad according to any one of claims 1 to 4, wherein the polyurethane substrate has a thickness of 1.1 mm to 3.0 mm; the polyurethane fiber substrate has a thickness of 0.8 mm to 2.2 mm; The thickness of the adhesive PSA-A layer is 0.8 mm to 2.0 mm; the thickness of the polyurethane vinyl adhesive PSA-B layer is 0.8 mm To 2.0mm. A method for preparing a polishing pad, comprising the steps of: 1) heating the prepolymer reactant to 75 ° C, heating the MOCA to 115 ° C, and then performing the gel at a temperature of 75 ° C to 115 ° C for a gel time of 5 to 15 minutes, wherein the weight ratio of the prepolymer reactant to the MOCA is 3.58:1; 2) adding 1% to 8% by weight of ultrashort polyester fiber or ultrashort aramid fiber to the pre- In the polymer reactant, the prepolymer reactant is thoroughly stirred and mixed with the MOCA at a rotation speed of 1500 rpm to 3500 rpm to obtain a mixture A; 3) the mixture A is placed in a centrifuge of 92 ° C to 110 ° C Performing a high temperature gel, gel for 30 minutes to 90 minutes to obtain a gelled polyurethane sheet; 4) transferring the gelled polyurethane sheet obtained in step 3) to a vulcanization oven at a temperature of 100 ° C to 120 ° Vulcanization at °C for 10 to 17 hours to obtain a vulcanized polyurethane sheet; and 5) using the vulcanized polyurethane sheet obtained in the step 4) as a polyurethane substrate, and forming the polyurethane fiber into a polyurethane fiber substrate by using a polyurethane rubber PSA-A is glued together as a backing phase, Then, a layer of polyurethane vinyl PSA-B is further coated on the other surface of the polyurethane fiber substrate, and then stamped and formed. After molding, two or more grooves are dug on the surface of the polyurethane substrate to obtain the polishing pad. The method for preparing a polishing pad according to claim 7, wherein the preparation steps of the ultra-short polyester fiber or the ultra-short aramid fiber are as follows: The terephthalic acid and ethylene glycol are used as raw materials to obtain polyethylene terephthalate by esterification reaction and polycondensation reaction, and then the ultrashort polyester fiber or the ultrashort granule is prepared by spinning and post-treatment. Polyester fiber; or transesterification reaction and polycondensation reaction using dimethyl terephthalate and ethylene glycol as raw materials to obtain polyethylene terephthalate, and then spinning and post-processing to make the ultra-short An aramid fiber or the ultrashort aramid fiber; wherein the ultrashort polyester fiber or the ultrashort aramid fiber is a powdery fiber having a diameter of 0.1 μm to 15 μm and uniformly arranged without polymerization. The method for preparing a polishing pad according to claim 7 or 8, wherein the prepolymer reactant is an isocyanate-terminated reaction product formed by reacting a prepolymer polyol and a polyfunctional aromatic isocyanate, the isocyanate terminated reaction The product contained 7.5% to 9.9% by weight of unreacted NCO. The method for preparing a polishing pad according to claim 9, wherein the prepolymer polyol comprises polytetramethylene ether glycol, polypropylene ether glycol, ethylene glycol diacetate or diacetyl adipate. Any one of diols; the polyfunctional aromatic isocyanate comprises 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, benzene-1,5-diisocyanate, Any one of methylamine diisocyanate, p-phenylene diisocyanate or xylene diisocyanate.