JP2002192457A - Abrasive composition and abrasive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive composition and an abrasive sheet that have a small variation in concentration and hardness and a small difference in polishing efficiency and in polished surface flatness throughout a lot of abrasive blocks for the abrasive sheet. SOLUTION: The abrasive composition comprises a reacting mixture of an isocyanate-terminated prepolymer (a), a diamine compound b and unexpanded or expanded microbodies c, wherein the compound b is a diamine compound having 4,4'-methylene-bis[2-chloroaniline] as the principal component and a pH of 7 to 9. The abrasive sheet is formed when the abrasive composition is cut into a given thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing sheet which is made by slicing a polishing material block and is capable of flattening a wiring forming surface on a semiconductor substrate efficiently and with high precision. The present invention relates to a polishing composition and a polishing sheet having less variation in the block.

[0002]

2. Description of the Related Art With the rapid development of the information industry in recent years, the demand for LSIs used in personal computers and the like has been rapidly increasing, and large capacity, multilayer wiring and high speed LSIs have been demanded. Thus, advanced LSI planarization technology is indispensable, but conventional planarization technology such as etching is insufficient, and a chemical mechanical polishing method called a CMP (Chemical Mechanical Polishing) method has already been widely used in the United States. Is being applied to

As an abrasive used for the CMP method, polyurethane resin having excellent mechanical strength and elasticity is considered to be promising. In Japanese Unexamined Patent Publication (Kokai) No. Hei 8-500622, an isocyanate-terminated prepolymer and a diamine compound composed of 4,4′-methylene-bis [2-chloroaniline] are mixed and agitated, and when reaction-curing is performed, expanded microfine particles are formed. A polishing substrate characterized by simultaneously adding and mixing hollow spheres has been proposed.

In Japanese Patent Application Laid-Open No. 11-322877, an isocyanate-terminated prepolymer, a diamine compound of the same chemical species as in the above-mentioned publication, and a microparticle which expands thermally due to heat during the reaction and curing thereof are mixed and stirred. An abrasive characterized by reaction hardening is disclosed. Further, Japanese Patent Application Laid-Open No. 11-322878 discloses an abrasive material using styrene beads which have already expanded as fine particles or styrene beads which expand thermally due to reaction heat when a specific diamine compound is cured by reaction with an isocyanate-terminated prepolymer. Is disclosed.

[0005]

However, even if the isocyanate-terminated prepolymer and the diamine compound disclosed in the above-mentioned publication are used, the resulting abrasive block has a large variation in density and hardness, and the block has a predetermined thickness. There has been a problem that the polishing efficiency and the flatness of the polished surface of the cut polishing sheet vary greatly between the polishing sheets in the block. An object of the present invention is to provide a uniform abrasive composition in an abrasive block, and to provide an abrasive sheet in which the polishing efficiency and the flatness of a polished surface are less varied among the abrasive sheets in the abrasive block. is there.

[0006]

Means for Solving the Problems The present inventors have found that the variation in the density and hardness in the abrasive block is due to the uneven distribution of the dispersed fine particles (c) in the block. A method of reacting and curing an isocyanate-terminated prepolymer and a diamine compound in a uniformly dispersed state was studied.

The present inventors have studied in detail the reaction curing properties of an isocyanate-terminated prepolymer and a diamine compound, particularly a diamine compound containing 4,4'-methylene-bis [2-chloroaniline] as a main component. The present inventors found that the NaOH catalyst remaining after the synthesis of the compound and the pH derived from HCl used to neutralize the NaOH catalyst greatly affected the reaction curability, and used the diamine compound having the pH of 7 to 9. Thus, the present invention has been completed by finding that a polishing composition and a polishing sheet can be produced in which the variation in the density and the height of the polishing material block is small, and the polishing efficiency and the flatness of the polished surface can be made without blurring in the polishing material block. I came to.

That is, in order to stabilize the polishing efficiency and the flatness of the polished surface, it is necessary that the composition of the abrasive block is homogeneous. For this purpose, an isocyanate-terminated prepolymer (a) and a diamine are required. The compound (b) and the fine particles (c) need a sufficient time to be stirred and dispersed uniformly, while the uniformly dispersed fine particles (c) form a liquid ((a)
Due to the specific gravity difference between the polishing composition and the mixed solution of (b), it is necessary to carry out reaction hardening before uneven distribution in the upper layer or lower layer of the polishing composition.

The most suitable diamine compound for reaction curing satisfying the above conditions is 4,4'-methylene-bis [2-
Chloroaniline] and a diamine compound having a pH of 7 to 9 as a main component, and a polishing sheet obtained by cutting the polishing material block obtained by using the diamine compound into a predetermined thickness is obtained from the polishing material composition. A composition having a uniform composition irrespective of position and having less variation in polishing characteristics within the block can be obtained.

[0010] The fluctuation of the pH of 4,4'-methylene-bis [2-chloroaniline] in the present invention is derived from the method for producing the compound. Usually, 4,4′-methylene-bis [2-chloroaniline] is converted to 2
-Synthesized by condensing chloroaniline and formaldehyde, but finally leaving remaining NaOH with HCl
Neutralize with. That is, the pH of 4,4′-methylene-bis [2-chloroaniline] is determined by the remaining amount of NaOH after synthesis and the amount of HCl used for neutralization.

Here, the pH of the diamine compound in the present invention is measured by the following method. 1) 60 ml of a solution obtained by mixing 2-propanol and water in a volume ratio of 10: 6 was stirred with a magnetic stirrer while stirring a 0.01 N HCl aqueous solution or a 0.01 N NaO solution.
An aqueous solution of H is added dropwise to adjust the pH at room temperature one minute after stopping to 7.0. 2) Precisely weigh 0.1 g of the diamine compound, add 2-propanol prepared in 1), stir with a magnetic stirrer for 5 minutes to obtain a uniform solution, and measure the pH at room temperature.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The isocyanate-terminated prepolymer (a) used in the present invention comprises an isocyanate compound and an active hydrogen group-containing compound, and isocyanate group (NCO) and active hydrogen group (H ^* ) equivalent ratio NCO / H ^* is 1.6 ~
It is an NCO-terminated oligomer produced by a heating reaction in the range of 2.6, preferably 1.8 to 2.2.

The isocyanate compound is not particularly restricted but includes 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate,
Aromatic diisocyanate compounds such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate,
Aliphatic diisocyanate compounds such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 1,6-hexamethylene diisocyanate (HDI), hydrogenated 4,4'-diphenylmethane diisocyanate (HMDI, trade name Hylen-W, Hüls) Alicyclic diisocyanate compounds such as 1,4-cyclohexane diisocyanate (CHDI) and norbornane diisocyanate. The above compounds may be used alone or in combination.

In addition to the above diisocyanate compounds, trifunctional or higher polyfunctional polyisocyanate compounds can be used. As polyfunctional isocyanate compounds,
A series of diisocyanate adduct compounds are commercially available as Desmodur-N (Bayer) and trade name duranate (Asahi Kasei Kogyo). Since these trifunctional or higher polyisocyanate compounds are apt to gel during the synthesis of a prepolymer when used alone, it is preferable to use them in addition to a diisocyanate compound.

The active hydrogen group-containing compound is not particularly limited, but is an organic compound having at least two or more active hydrogen atoms, and a compound generally called a polyol compound or a chain extender in the field of polyurethane is used. be able to. An active hydrogen group is a functional group containing hydrogen that reacts with an isocyanate group, and examples include a hydroxyl group, a primary or secondary amino group, and a thiol group (SH).

The polyol compound is an oligomer having a molecular weight of about 500 to 10000 as determined by a terminal group determination method, and includes the following polyether polyols and polyester polyols.

Examples of the polyether polyol include polyoxypropylene obtained by adding propylene oxide to one or more polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, and trimethylolpropane. Polyols, polyoxyethylene polyols obtained by adding ethylene oxide, polyols obtained by adding butylene oxide, styrene oxide, and the like, and obtained by adding tetrahydrofuran to the polyhydric alcohol by ring-opening polymerization. Examples thereof include polyoxytetramethylene polyols. Copolymers using two or more of the above-mentioned cyclic ethers can also be used.

As the polyester polyol, one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, glycerin, trimethylolpropane, pentaerythritol or other low molecular weight polyhydric alcohols are used. Polycondensation with glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, dimer acid, hydrogenated dimer acid or other low molecular dicarboxylic acid or oligomeric acid Examples thereof include polyols such as union, ring-opened polymers of cyclic esters such as propiolactone, caprolactone, and valerolactone. What is a chain extender?
Compounds having a molecular weight of about 500 or less, for example, aliphatic low molecular weight glycols represented by ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, etc., triols, methylenebis-o-chloroaniline ( MOCA), aromatic diamines such as dicyclohexylmethane-4,4′-diamine,
Aromatic diols such as 1,4-bishydroxyethoxybenzene (Cureamine H (manufactured by Ihara Chemical Co.)) and m-xylylenediol (manufactured by Mitsubishi Gas Chemical Company) are exemplified.

Diamine compound (b) used in the present invention
Is 4,4'-methylene-bis [2-chloroaniline]
Is a diamine compound containing as a main component. The reason for using a diamine compound containing 4,4'-methylene-bis [2-chloroaniline] as a main component is that it is suitable for preparing an abrasive composition having a uniform reaction curing property with an isocyanate-terminated prepolymer. is there.

That is, in preparing a uniform abrasive composition, the isocyanate-terminated prepolymer, the diamine compound and the fine particles are stirred and uniformly dispersed, and then the uniformly dispersed fine particles are mixed with the isocyanate-terminated prepolymer and the diamine compound. The two requirements for curing before the mixture is unevenly distributed in the upper layer or the lower layer due to the difference in specific gravity with the mixture with the mixture are necessary. One of the diamine compounds, 4,4′-methylene The diamine compound containing -bis [2-chloroaniline] as a main component, when the reaction curing starts, rapidly proceeds and cures in an extremely short time, so that the above requirements can be satisfied, and a uniform abrasive composition Can be created.

The present inventor has further investigated the reaction hardening characteristics and found that the pH of the diamine compound containing 4,4'-methylene-bis [2-chloroaniline] as a main component was changed by the reaction with the isocyanate-terminated prepolymer. We noticed that it had a great effect on. If the pH exceeds 9, the reaction starts immediately after stirring and mixing, and a sufficient mixing and stirring time for uniformly dispersing the microparticles cannot be secured. On the other hand, if the pH is less than 7, the reaction is totally suppressed, so that sufficient mixing and stirring time for uniform dispersion can be ensured, but rapid reaction hardening after the start of the reaction is impeded, and the stirring is uniform. The fine particles dispersed in the polymer are unevenly distributed in the upper layer of the cured product.

The microparticles used in the present invention are not particularly limited as long as they form microcells in the abrasive composition, and may be those which have been expanded in advance to have a desired cell diameter.
Although it is not expanded at the time of mixing, it may expand by reaction heat at the time of reaction curing and have a desired cell diameter. Specific examples include styrene beads, acrylic beads, and copolymer beads of vinylidene chloride and acrylonitrile, which are already expanded or unexpanded. The particle diameter of (c) after expansion is preferably 150 μm or less in terms of average particle diameter from the viewpoint of uniform polishing performance on the polishing sheet surface. Particularly preferably, it is 100 μm or less.

In the present invention, the isocyanate-terminated urethane prepolymer (a) and the diamine compound (b),
The mixing ratio with 4,4'-methylene-bis [2-chloroaniline] is determined by the molar ratio of the isocyanate group to the amino group contained in each. The ratio is NH
It is preferable that _{2 /} NCO = 0.8 to 1.1. Particularly preferably, it is 0.8 to 1.0.

It is preferable that the added amount of the unexpanded or unexpanded microparticles (c) is 0.1 to 10 parts by weight based on 100 parts by weight of the composition comprising (a) + (b). . Particularly preferably, it is 2 to 5 parts by weight.

In the present invention, (a) + (b) +
For the composition comprising (c), at any time until mixing and curing, if necessary, stabilizers such as antioxidants, lubricants,
Pigments, fillers, antistatic agents and other additives can be added.

[0026]

EXAMPLES Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited to these examples.

(Example 1) Expancel 55 was added to 100 parts by weight of adiprene L-325 (isocyanate-terminated prepolymer, NCO = 9.25%, manufactured by Uniroyal).
A mixture of 3.2 parts by weight of 1DE (pre-expanded microparticles, vinylidene chloride-acrylonitrile copolymer beads, manufactured by Nippon Philite Co., Ltd.) with a dissolver is degassed under reduced pressure. After adjusting the temperature of the prepolymer mixture to 70 ° C., 12
After adding 26 parts by weight of 4,4'-methylene-bis [2-chloroaniline] adjusted to pH 7.2 at a temperature of 0 ° C., stirring and mixing with a dissolver, casting the mixture into a mold, followed by reaction curing. Then, the resultant was cured in an oven at 120 ° C. for 5 hours to obtain an abrasive block. The block was cut to a thickness of 1.3 mm to prepare a polishing sheet. For the 12 polishing sheets, a polishing test of a silicon wafer (wafer load 30
0 g / cm ² , platen rotation speed 60 rpm, polishing time 1
20 seconds). Table 1 shows the results. Here, the in-plane uniformity of each polishing sheet was calculated from the measurement of the wafer film thickness after completion of the polishing test according to the following equation. In-plane uniformity (%)
= (Maximum film thickness-minimum film thickness) / (2 × average film thickness) × 100
Polishing rate is 1240-1340 ° / min (standard deviation:
33.1), the in-plane uniformity was in the range of 3 to 8%.

(Example 2) Except that 4,4'-methylene-bis [2-chloroaniline] having a pH of 8.8 was used,
A polishing composition and a polishing sheet were prepared in the same manner as in Example 1, and a polishing test was performed on a silicon wafer. The polishing rate was 1260-1360 ° / min (standard deviation: 340).
3) The in-plane uniformity was in the range of 5 to 8% (see Table 1).

Comparative Example 1 An abrasive composition was prepared in the same manner as in Example 1 except that 4,4′-methylene-bis [2-chloroaniline] having a pH of 5 was used.
Since the reaction did not proceed sufficiently, a good abrasive composition was not obtained.

Comparative Example 2 An abrasive composition was prepared in the same manner as in Example 1 except that 4,4′-methylene-bis [2-chloroaniline] having a pH of 11 was used. The pot life was short, and sufficient time for pouring into a mold was not obtained, and a good abrasive composition could not be produced.

[0031]

[Table 1]

[0032]

As described above, the isocyanate-terminated prepolymer (a), the diamine compound (b) and the fine particles (c)
In a polishing sheet obtained by slicing an abrasive block obtained by mixing and reacting the above, a (4)-(4) -methylene-bis [2-chloroaniline] as a main component and a pH of 7 or more and 9 or less. By using a diamine compound having the following, a polishing sheet can be provided in which the polishing efficiency and the flatness of the polished surface have less variation in the abrasive material block.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Ono 2-1-1 Katata, Otsu-shi, Shiga Inside Toyobo Co., Ltd. Research Institute (72) Inventor Tetsuo Shimomura 2-1-1 Katata, Otsu-shi, Shiga Inside Toyobo Co., Ltd. Research Laboratory (72) Masahiko Nakamori 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory F-term (reference) 3C058 AA07 AA09 CA01 CB01 CB03 4F071 AA53 AC12 AH19 BC01 BC16 4J034 BA02 CA15 CB03 CC12 CC22 CC26 CC45 CC53 CC61 CC67 DC50 DF01 DF16 DF20 DF22 DG03 DG04 HA01 HA07 HC03 HC12 HC22 HC46 HC52 HC64 HC71 HC73 JA42

Claims (2)

[Claims] 1. An abrasive composition obtained by mixing and reacting an isocyanate-terminated prepolymer (a), a diamine compound (b) and a microparticle (c), wherein (b) is 4,
An abrasive composition comprising a diamine compound containing 4'-methylene-bis [2-chloroaniline] as a main component and having a pH of 7 or more and 9 or less. 2. A diamine compound (b) having an isocyanate-terminated prepolymer (a), having a pH of 7 or more and 9 or less and containing 4,4'-methylene-bis [2-chloroaniline] as a main component, and fine particles ( a) a polishing sheet obtained by cutting an abrasive obtained by mixing and reacting with c) to a predetermined thickness.