CN1314517C - Manufacturing method of integrally formed PU polishing pad - Google Patents

Abstract

The invention utilizes the polyalcohol resin, polyamine resin, polythiol resin containing active hydrogen functional machine and isocyanate resin containing-NCO functional machine, and utilizes the assistance of adding auxiliary gas to quickly and uniformly distribute the mixture in the mould under the condition of high pressure and low temperature and in the Reaction injection molding mode so as to obtain the integrally-formed flexible PU foaming grinding pad with the characteristics of quick demoulding and excellent grinding characteristics. The invention is used together with the grinding fluid, and can be widely applied to the grinding in the fields of wafers, optical glass and the like.

Description

Manufacturing method of integrally formed PU polishing pad

technical field

The present invention relates to the method for manufacturing the PU foaming polishing pad that can grind wafers (wafers) and optical lenses (TFT-LCD, ...) and other related products, and the integrally formed foaming pad obtained by the method PU abrasive pad products.

Background technique

During the development of semiconductor memory (Memory) and logic devices (Logic device), in order to increase the density of electronic components and reduce production costs, there is a tendency to increase the aspect ratio (Aspect ratio) and increase the number of wire layers in the component manufacturing process. However, when forming such a multi-layer wire structure, as the number of stacked layers increases, the surface height difference and twist of the chip will also increase. Therefore, in order to form more layers of wire structure and ensure its yield, it is possible to In the manufacturing process, the technology of eliminating the fine unevenness of the surface and achieving the so-called global planarity has become the focus of attention. The first to propose this method was the IBM Corporation of the United States. IBM has not only developed a chemical mechanical polishing (CMP, Chemical Mechnical Polishing) precision grinding method, but also proposed a metal damascene method (Damascene) that uses chemical mechanical polishing to make embedded wires. Basically, chemical mechanical polishing is planarized by means of the relative movement between the slurry of suspended fine particles and the polishing pad with elasticity and appropriate hardness, acting on the surface of the chip. When the polishing pad moves on the surface of the chip, the particles at the contact point are pressed against the surface of the chip, and the friction and sliding between the surface of the chip and the particles has the effect of abrasion. The softness, hardness, roughness and other physical properties of the polishing pad will affect the interaction of the abrasive particles in the polishing liquid, and the irregular relationship between the horizontal direction and the vertical direction will appear. Under a certain pressure, the force exerted in the horizontal direction of the polishing pad is an important factor in determining whether the planarization is good or bad. In the chemical mechanical polishing process, the polishing pad needs to withstand the pressure from the polishing head and transmit it to the surface to be polished to maintain the flatness during polishing, and the uniform dispersion of the polishing liquid particles is an important factor affecting the uniformity of the surface after polishing. Therefore, the grinding pad must have enough hardness to provide grinding effect and micropores enough to hold the grinding liquid. Generally speaking, the larger the micropores, the more uniformly dispersed the fine particles in the grinding liquid can be. At the same time, it is more able to accommodate the residue removed by grinding and the invalid grinding slurry, but the excessively large micropores cannot maintain a consistent grinding pressure. , resulting in a decrease in the flatness of the polished surface.

After the polishing pad has been used for a period of time, since the grinding residue and abrasive particles are accumulated in the micropores of the polishing pad, it is necessary to scrape or brush the polishing pad for conditioning to remove the deposits on the polishing pad. However, when the polishing pad is vitrified, the polishing function cannot be restored through the adjustment steps, that is, the polishing pad has reached the end of its service life. Therefore, based on the consideration of cost reduction and productivity improvement, improving the service life of the polishing pad is highly anticipated by the industry.

Porous materials such as those described in US Pat. No. 3,284,274 have been used as abrasive materials in the past.

Subsequently, US Patent No. 4,841,680 disclosed a wet PU polishing pad with upside-down micropores. The polishing pad is made by the known solvent/non-solvent polymer coagulation technology (polymercoagulation technology). The manufacturing process is to first react polyalcohols and isocyanates at 80°C, and then dissolve them in dimethylformamide ( DMF) to form a polymer solution. After coating the polymer solution on the substrate, immerse it in a water bath to completely/fully coagulate the polymer, and then replace the original solvent (such as DMF) with another solvent (such as water) , and then rely on high temperature, drying and volatilization of the residual solvent in the polymer to form irregularly shaped holes. US Patent No. 6,095,902 uses copolymerized polyether polyol and polyester polyol, or uses polyols containing more than three kinds, to produce a porous elastic wet PU polishing pad. Both of these two patents use another method of solvent replacement or high temperature to volatilize the residual solvent to form a polymer with uneven micropores inside, and then use a blade or rotating grinding cylinder to remove the surface layer of the polymer to make the pores below it Exposed, and then laminated with the backing substrate to make a polishing pad, or foam the polymer in a mold to form a cake, cut into single pieces, and then stick it to the substrate to make a polishing pad . Since the polishing pad obtained by the above method has to be completed by forming PU foam polymer, removing the surface layer/cutting into single pieces and bonding, the manufacturing process is very labor-intensive, and it is not easy to remove the surface layer/cut into single pieces. Control, resulting in uneven fineness of micropores, small surface openings, increased hole wall ratio in the working surface, and surface opening diameters smaller than bottom diameters, which are not conducive to grinding stability (such as unpredictable service life, abrasive particles and ground The problem of uneven surface contact) is prone to occur.

In addition, U.S. Patent No. 5,578,362 discloses a polishing pad comprising a polymeric matrix impregnated with a plurality of hollow, flexible, organic polymeric microelements, the polishing pad having a working surface and a surface close to the working surface. subsurface. A portion of the polymeric microunits on the working surface is exposed to the working environment and contains the slurry, while another portion of the polymeric microunits buried in the subsurface is not exposed to the working environment. Since a portion of the polymeric microunits on the working surface is exposed to the working environment, the working surface is made relatively softer than the subsurface. As the pad wears and the polymeric microunits are exposed to the working environment, the subsurface becomes a relatively soft working surface, thereby self-regenerating a new working surface with consistent abrasive properties. However, the method of this patent needs to go through the steps of mixing the polymer matrix, blending the hollow elastic polymer microspheres, feeding the mixture into a mold, aging the mixture at a temperature relatively higher than normal temperature, cooling and surface treatment or modification to complete the polishing pad. The production is not only time-consuming but also difficult to maintain stable operating conditions, thus greatly reducing the industrial applicability of the method. U.S. Patent No. 6,022,268 discloses a polishing pad composed of a hydrophilic abrasive layer that itself does not have the ability to absorb or transport many slurry particles. Surface shape and large texture. This patent does not cut the polishing pad from larger materials, but uses solidification to make the polishing layer, and does not cut or chip the polishing surface, but at least a part of the large texture is applied to the polishing surface. From the embodiments of this patent, it can be seen that except for utilizing injection molding to have the final size and groove design of the required abrasive pad, the other formulations and molding conditions are the same as those of U.S. Patent No. 5,578,362. Therefore, although this patent Effectively improve the large defects (macro-defcts) and grinding performance caused by cutting on the grinding surface, but there are still disadvantages such as time-consuming production. U.S. Patent No. 6,239,188 discloses adding expanded microballoons (microballons) with two sizes of 10 to 50 μm and 80 to 100 μm in a specific range of weight ratios to polyurea ester prepolymers terminated with isocyanate and active hydrogen-containing compound, and aging the mixture to obtain a polyurethane molded product for polishing pads with better polishing flatness and better polishing rate. Although this patent can improve the flatness of the ground material that cannot be obtained by using only one kind of microballoon in the known art, but like the US Patent No. 5,578,362 and the US Patent No. 6,022,268, this patent also needs to be higher than normal temperature. Heating temperature and long curing time are unfavorable for industrial application.

Therefore, there is still an urgent need in the industry to provide a polishing pad with stable and excellent polishing properties that can be manufactured quickly.

Contents of the invention

The object of the present invention is to provide a rapid manufacturing method for obtaining a highly flat, uniform microporous integrated PU polishing pad by means of reaction injection molding under high pressure.

Another object of the present invention is to provide a PU grinding pad that can be used for grinding high-precision objects such as semiconductor wafers, metallurgical samples, storage disk surfaces, optical elements, lenses or wafer masks.

In order to achieve the above-mentioned purpose, the present invention adds the auxiliary gas amount of specific range volume ratio in the resin containing active hydrogen functional group, and by virtue of inorganic or organic chemical or physical blowing agent mixed with the specific composition of the resin containing -NCO functional group, Under normal temperature and high pressure, the above mixture is formed by reaction injection molding to obtain an integrally formed PU polishing pad with excellent flatness and uniform micropores.

Description of drawings

Fig. 1 shows the continuity and uniformity of bubbles in Example 2 when magnified by a scanning electron microscope (SEM) at 100 times.

Figure 2 shows the continuity and uniformity of bubbles observed in Example 3 when magnified by a scanning electron microscope (SEM) at 100 times.

Detailed ways

The manufacture method of the present invention uses the resin containing active hydrogen functional groups (selected from polyalcohol resins containing -OH functional groups, polyamine resins containing -NH functional groups, polythiol resins containing -SH functional groups) ; add additives (selected from chain extenders, blowing agents, foam regulators, catalysts) and auxiliary gases (selected from air, nitrogen, inert gases); and add resins containing -NCO functional groups (selected from aliphatic isocyanates Acid resin, aromatic isocyanate resin), mix the above ingredients evenly. Then pour it into the mold to form a microporous foamed PU polishing pad.

With the help of the auxiliary gas, the reactants can be quickly and evenly distributed in the mold by the above method, and the prepared PU polishing pad has the characteristics of rapid demoulding. And it has appropriate strength and flexibility. After foaming, the size of the holes in the effective grinding part is evenly distributed. After surface processing, most of the holes are open cells, which is beneficial to the dispersion and transmission of the grinding liquid.

In the preferred embodiment of the production method of the present invention, the reaction procedure first adds 5 to 30% by weight of a chain extender (preferably 10 to 20% by weight), 0.1 10% by weight of blowing agent, 0.1 to 10% by weight of foam stabilizer, 0.1 to 1.0% by weight of additives such as catalysts, the aforementioned weight % is based on the resin (such as polyalcohol resin) containing -OH functional group and Calculate based on the total weight of the chain extender; and add 5 to 30% by volume (preferably 10 to 15% by volume) of auxiliary gas to be mixed, and this auxiliary gas is selected from air, nitrogen and inert gas; and add - The resin of NCO functional machine, such as the isocyanate resin of pre-polymerization type; And adjust the resin content that contains-NCO functional machine and the resin content that contains-OH functional machine so that the ratio (index) of -NCO and -OH is at 0.6 to 1.5, relatively Preferably between 0.95 and 1.1; then at a temperature of 20 to 100°C, preferably 20 to 60°C, and under a pressure of 2 to 20Mpa, preferably 5 to 20MPa, the reaction mixture of the above steps is injected out of the mold Inner, and rapidly foamed to form a PU polishing pad with a polyurethane structure. The grinding pad manufactured by the present invention can be demoulded within 3 to 5 minutes through repeated verification.

In the method of the present invention, the structure and formula of the polyalcohol resin can be adjusted according to the needs of the product, and then flexible PU polishing pads with uniform and continuous open pores of different hardness, density, elongation and strength can be obtained. In addition, by virtue of the design of the mold and the change of the polyalcohol resin formula, the method of the present invention can also produce monolithic symmetrical integral molding (that is, the surface layer close to the mold does not foam, and the surface layer away from the surface layer gradually Symmetrical formation of fine continuous holes) PU microcellular foaming products. The above-mentioned one-piece symmetrical PU microcellular foamed product can be cut symmetrically in the middle to obtain two pieces with a double-layer structure (that is, a harder surface layer and a softer buffer layer below the surface layer) . The surface layer of the foamed product of the present invention has a higher hardness, similar to the harder layer of a double-layer polishing pad, which can maintain a better planarity when grinding wafers. In addition, by virtue of foaming agent and auxiliary gas With the help of the softer layer of the grinding pad, it can provide better uniformity (umiformity) when grinding.

In the method of the present invention, the single-piece integrated PU polishing pad obtained by high pressure and reaction injection molding is subjected to fine treatment on the surface, and then a single-layer type (PU foam product+pressure-sensitive adhesive tape) is obtained. The surface of this type of polishing pad has appropriate rigidity (hardness), which can ensure better planarization and higher quality. In addition, the surface of the polishing pad can also be deformed with the ups and downs of the surface pattern of the chip, thus obtaining better uniformity.

Suitable polyisocyanate prepolymers of the present invention include aliphatic and aromatic isocyanate resin monomers and 4, 4' and 2', 4 polycyanate resins with different mixing ratios and different functional groups, the above-mentioned Specific examples of isocyanate monomers include toluene diisocyanate (toluene diisocyanate), triphenylmethane-4, 4', 4"-triisocyanate (triphenylmethane-4, 4', 4"-triisocyanate), benzene-1 , 3,5-triisocyanate (benzene-1,3,5-trisocyanate), hexamethylene diisocyanate (hexamethylene diisocyanate), xylene dimethyl diisocyanate (xylene diisocyanate), chlorophenylene diisocyanate (chlorophenylene diisocyanate), di Cyclohexylmethane 4,4'diisocyanate (dicyclohexylmethane 4,4'diisocyanate) and methylenebisdiphenyl diisocyanate (methylenebisdiphenyl diisocyanate).

Suitable polyalcohol resins in the present invention are selected from polyether alcohols, polyester alcohols, polycaprolactone series, polyamine resins, polythiol resins and combinations thereof, and its specific examples can be exemplified by polyoxypropylene ether Polyol (PPG), polymer polyol (copolymer of polystyrene and acrylonitrile), polyolefin polyol (synthesized from polybutadiene), copolyether polyol, polyether polyamine and polytetrahydrofuran polyol ( PTMEG).

Specific examples of chain extenders suitable for the present invention include 1,4-butanediol, ethylene glycol, propylene glycol, glycerol, 4,4'-methylenebis(3-chloro-2,6-ethylaniline), triethanolamine , Triisopropanolamine and aromatic and aliphatic polyamines. The added amount of the above-mentioned chain extender is usually 5 to 30% by weight, preferably 10 to 20% by weight.

Suitable blowing agents of the present invention include inorganic blowing agents and organic blowing agents. The specific examples of inorganic blowing agents are water and carbon dioxide; the specific examples of organic blowing agents can be exemplified by propane, butane, pentane, acetone, Dichloromethane, hydrogenated chlorofluorocarbons (such as HCFC-22, HCFC-141b, etc.) or hydrogenated fluorocarbons (such as HFC-134a, HFC-365mfc, HFC-227ea, and HFC-245fa), etc.

Foam stabilizers suitable for the present invention include silicone compounds, oxiraneated polyalcohols or mixtures thereof, specific examples of which may be exemplified by oxiraneated polypolyols, siloxanated oxirane , Co-grafted compounds of propane.

The present invention will be further illustrated with the following examples, but the scope of the present invention should not be limited thereto.

Example 1 formula weight% Polymer polyol (Mw=6000) 79 1,4 Butanediol twenty one Organic amine catalyst 0.46 water 0.2 Silicone foam stabilizer 1.0 MDI isocyanate prepolymer (NCO=23%) 50

The use temperature of the raw materials in Example 1 is 32° C., the mixing amount of air is 8 volume %, the mold temperature is 50° C., and the use pressure of the reaction injection molding machine is 15 MPa. With the above formula and conditions, the measured physical properties are as follows: Tensile strength (Mpa) 15 Elongation(%) 120 Hardness (shore-D) 55 Density (g/cm ³ ) 0.78 Compression ratio(%) 1.02

Example 2 formula weight% Polyester polyol (Mw=1000) 84 Ethylene glycol 16 Organic amine catalyst 1.0 water 0.2 Silicone foam stabilizer 1.0 MDI isocyanate prepolymer (NCO=29.5%) 100

The use temperature of the raw materials in Example 2 is 55°C, the mixing amount of air is 12% by volume, the mold temperature is 60°C, and the use pressure of the reaction injection molding machine is 15MPa. Observation with a scanning electron microscope (SEM) shows that the continuity and uniformity of the bubbles are good, as shown in FIG. 1 . With the above formula and conditions, the measured physical properties are as follows: Tensile strength (Mpa) 19 Elongation(%) 180 Hardness (shore-D) 60 Density (g/cm ³ ) 0.7 Compression ratio(%) 0.98

Example 3 formula weight% Polycaprolactate (Mw=1000) 84 Ethylene glycol 16 Organic amine catalyst 0.45 Pentane 6 Silicone foam stabilizer 1.0 MDI isocyanate prepolymer (NCO=28%) 100

The use temperature of the raw materials in Example 3 is 50° C., the mold temperature is 60° C., and the use pressure of the reaction injection molding machine is also 15 MPa. The continuity and uniformity of the bubbles are shown in Figure 2. With the above formula and conditions, the measured physical properties are as follows:

Tensile strength (Mpa) 17.8 Elongation(%) 156 Hardness (shore-D) 58 Density (g/cm ³ ) 0.7 Compression ratio(%) 1.01

In the above-mentioned embodiments, the adjustment of the density is mainly based on different chain extenders, foaming doses and injection volumes injected into the metal mold to obtain different densities and hardness values and to further change and adjust the PU polishing pad various physical properties and parameters.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of protection of the invention should be defined by the claims.

Claims (28)

1, a kind of manufacture method of PU grinding pad is characterized in that: comprising:

(a) in the resin that contains the reactive hydrogen functional group, add additive and assist gas, and add contain-NCO functional group's resin mixed;

(b) mixture with step (a) injects in the mould, forms the PU grinding pad of tool microporous foam.

2, manufacture method as claimed in claim 1 is characterized in that: this resin that contains the reactive hydrogen functional group is selected from polyalcohols resin, polyamine resinoid and polymercaptan resinoid.

3, manufacture method as claimed in claim 1 is characterized in that: this additive is selected from chain elongation agent, blowing agent, surfactant and catalyst.

4, manufacture method as claimed in claim 1 is characterized in that: this assist gas is selected from air, nitrogen and inert gas.

5, manufacture method as claimed in claim 1 is characterized in that: and this contains-and NCO functional group's resin is selected from aliphatic isocyanate resin and aromatic series isocyanate resin.

6, a kind of manufacture method of PU grinding pad is characterized in that: comprising:

(a) containing-add additive, assist gas in OH functional group's the resin and contain-NCO functional group's resin, adjust this to contain-NCO functional group's resin and this contain-OH functional group's resin content makes it-NCO and-ratio of OH is between 0.6 to 1.5;

(b) the mixture reaction of step (a) is penetrated in mould, foaming forms the PU grinding pad with polyureas ester structure.

7, manufacture method as claimed in claim 6 is characterized in that: and this contains-and OH functional group's resin is the polyalcohols resin.

8, manufacture method as claimed in claim 6, it is characterized in that: this additive comprises: the surfactant of the chain elongation agent of 5 to 30 weight %, the blowing agent of 0.1 to 10 weight %, 0.1 to 10 weight %, the catalyst of 0.1 to 1.0 weight %, with this contain-OH functional group's resin and the gross weight of this chain elongation agent are basic calculation.

9, manufacture method as claimed in claim 6 is characterized in that: this assist gas is selected from air, nitrogen and inert gas.

10, manufacture method as claimed in claim 6 is characterized in that: and this contains-and NCO functional group's resin is selected from aliphatic isocyanate resin and aromatic series isocyanate resin.

11, manufacture method as claimed in claim 6 is characterized in that: should-NCO and-ratio of OH is between 0.95 to 1.1.

12, a kind of manufacture method of PU grinding pad is characterized in that: comprising:

(a) in the polyalcohols resin, add the chain elongation agent of 5 to 30 weight %, the blowing agent of 0.1 to 10 weight %, the surfactant of 0.1 to 10 weight %, the catalyst of 0.1 to 1.0 weight %, gross weight with this polyalcohols resin and this chain elongation agent is a basic calculation, and the assist gas amount of adding 5 to 30 volume %, and the isocyanate resin that adds the pre-polymerization mould assembly mixed, and isocyanate resin, the polyalcohols resin compound of pre-polymerization mould assembly are adjusted it-NCO and-ratio of OH is between 0.6 to 1.5;

(b) 20 to 100 ℃ temperature, under 2 to 20Mpa the blend pressure, the mixture reaction of step (a) is penetrated in mould, foaming forms the PU grinding pad with polyurethane structure.

13, manufacture method as claimed in claim 12 is characterized in that: the assist gas amount of this adding is 10 to 15 volume %.

14, manufacture method as claimed in claim 12 is characterized in that: the amount of this chain elongation agent is 10 to 20 weight %.

15. manufacture method as claimed in claim 12 is characterized in that: this temperature is 20 to 60 ℃.

16. manufacture method as claimed in claim 12 is characterized in that: this pressure is 5 to 20MPa.

17, manufacture method as claimed in claim 12 is characterized in that: this polyalcohols resin is selected from polyethers alcohols, polyester alcohols, polycaprolactone series, polyamine resinoid, polymercaptan resinoid and combination thereof.

18, manufacture method as claimed in claim 12, it is characterized in that: the isocyanate resin of this pre-polymerization mould assembly is selected from aliphatic, aromatic isocyanate resin monomer and 4,4 ' and 2 ', 4 different mixing proportion, sense radix are 2 to 4 pre-polymerization mould assembly isocyanates resin and combination thereof.

19, manufacture method as claimed in claim 12 is characterized in that: this NCO and-ratio of OH is between 0.95 to 1.1.

20, manufacture method as claimed in claim 12 is characterized in that: this blowing agent is an inorganic foaming agent.

21, manufacture method as claimed in claim 20 is characterized in that: this inorganic foaming agent is water or carbon dioxide.

22, manufacture method as claimed in claim 12 is characterized in that: this blowing agent is an organic foaming agent.

23, manufacture method as claimed in claim 22 is characterized in that: this organic foaming agent is selected from propane, butane, pentane, acetone, carrene, hydrogenation chloro-fluorocarbon compound and hydrogenation fluorocarbons.

24, manufacture method as claimed in claim 23 is characterized in that: this hydrogenation chloro-fluorocarbon compound is selected from HCFC-22 and HCFC-141b.

25, manufacture method as claimed in claim 23 is characterized in that: this hydrogenation fluorocarbons is selected from HFC-134a, HFC-365mfc, HFC-227ea and HFC-245fa.

26, manufacture method as claimed in claim 12 is characterized in that: this surfactant is selected from the polyalcohols and the combination thereof of siliconization thing, oxiraneization.

27, a kind of one-body molded PU grinding pad is characterized in that: by claim 1, and 6, or the prepared grinding pad of 12 described manufacture methods has following properties: 0.3 to 0.9g/cm ³Global density, the hardness of 30 to 80Shore D, the micropore size of 5 to 80 μ m.

28, one-body molded PU grinding pad as claimed in claim 27, it is characterized in that: this grinding pad is used to grind the object that is selected from semiconductor crystal wafer, metallurgical samples, storage disks surface, optical element, eyeglass and wafer cohort that light shield becomes.

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