JPH09326380A - Method for removing particle from surface of basic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing particles on the surface of a basic material in which the workability of stripping work is enhanced while reducing the residue on the surface of the basic material. SOLUTION: (a) 20-78.9 pts.wt. of radical polymeric monomer, (b) 0.1-10 pts.wt. of a vinyl monomer having a reactive silyl group and copolymerable with the (a) radical polymeric monomer, (c) 1-20 pts.wt. of radical polymeric silicone based macromonomer copolymerable with the (a) radical polymeric monomer, and (d) 20-50 pts.wt. of (meta)acrylonitrile are copolymerized to provide a copolymeric film on the surface of a basic material and then the film is stripped off therefrom. Since the copolymer thus provided exhibits high adhesion to the surface of the basic material and good balance with the toughness of the film, the film can be stripped smoothly and contamination on the surface of the basic material can be suppressed after stripping the film.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for removing particles on a surface of a base material, and more specifically, after a coating of a predetermined copolymer is provided on the surface of the base material, the coating is peeled from the base material. By physically removing the particles on the surface of the substrate. The removal method of the present invention is particularly suitable for the purpose of physically removing particles such as dust adhering to a semiconductor wafer or a glass substrate for a photomask. In the present specification, "(meth) acrylate" means "at least one of acrylate and methacrylate", and "(meth) acrylonitrile" means "at least one of acrylonitrile and methacrylonitrile".

[0002]

2. Description of the Related Art As a typical method for physically removing particles such as dust adhering to a semiconductor wafer or a glass substrate for a photomask, a substrate such as a semiconductor wafer is immersed in water or an organic solvent, and ultrasonic waves are applied. A method of removing particles by vibrating and removing them by vibration (ultrasonic cleaning method), a method of spraying water or an organic solvent onto the surface of the substrate while bringing a brush into contact with the surface of the substrate to remove particles (brushing) There are two cleaning methods). However, according to the ultrasonic cleaning method described above, it is difficult to remove the particles firmly attached to the surface of the substrate. Further, according to the above-mentioned brushing cleaning method, particles removed from the substrate adhere to the brush, and the particles adhere to the substrate to be processed next and contaminate the substrate, so-called mutual contamination is likely to occur. is there.

Therefore, in Japanese Patent Laid-Open No. 7-74137, instead of the above method, a coating liquid is supplied to the substrate surface to form a thin film, and the thin film is peeled off to remove particles on the substrate surface. That is, a method of removing particles from the surface of the substrate is disclosed.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Japanese Patent Laid-Open No. 37 describes that "vinyl acetate-based or polyurethane-based" can be used as the type of coating liquid used for forming a thin film. However, the above publication does not describe the specific composition of the coating liquid satisfying these conditions. In addition, when a film composed of a general vinyl acetate-based or polyurethane-based resin solution is formed on the surface of a semiconductor wafer or a glass substrate for a photomask, the adhesion between the film and the substrate surface is high, so the film is Cannot be easily peeled off.

On the other hand, a so-called strippable paint composition is known as a material for forming a film which can be peeled off from the surface of a substrate. For example, JP-A-3-14037
Japanese Patent Publication No. 3 discloses a peelable coating composition in which a repellent property is improved by incorporating a water repellent agent into the composition. Further, in JP-A-4-310271, a hydrophobic coating as a release agent is formed on the surface of a base material, and a strippable coating is formed on the hydrophobic coating to form a strippable coating / hydrophobic coating. There is disclosed a method for forming a strippable coating film in which the peeling property between the material and the material is improved. However, in the application of removing particles from the substrate surface, when using a conventional strippable paint composition containing a water repellent and a release agent, the peelability of the coating film is improved but these There is a problem that the additive remains on the wafer. Therefore, it is not preferable for use in removing particles attached to a semiconductor wafer, a glass substrate for a photomask, or the like.

Further, in such a particle removing composition, it is necessary to determine the composition in consideration of the strength of the film in addition to the peelability of the film. This is because when the strength of the coating is weaker than the adhesion between the coating and the substrate, the coating stretches during peeling and the workability deteriorates, and furthermore, the coating breaks during peeling and the This is because there arises a problem that only a part can be peeled off. Further, the coating is required to have strength and toughness. This is because, in the case of a film that is high in strength but is brittle, the film may break during peeling and only a part of the film can be peeled off, or fragments of the film may remain on the substrate. That is, as the composition for removing particles on the surface of the substrate, in addition to having good particle removability, a film having a good balance of “peelability”, “strength” and “toughness”, In addition, it is preferable to form a film with less contamination on the surface of the substrate after the film is peeled off.

An object of the present invention is to provide a method for removing particles on the surface of a substrate, which is suitable for the purpose of physically removing particles such as dust, and which uses a composition satisfying each of the above conditions.

[0008]

The present inventors have focused on copolymerizing a silicone macromonomer as a method for improving the peelability of the coating without contaminating the surface of the substrate after the coating is removed. Furthermore, the present invention has been completed by finding that by copolymerizing (meth) acrylonitrile and a vinyl monomer having a reactive silyl group as a cross-linking component, the coating becomes tough and peeling workability becomes good, and the present invention was completed. is there.

That is, the method for removing particles on the surface of a substrate according to the first aspect of the present invention (hereinafter referred to as the "removing method of the present invention" or "the present removing method") is (a) a radical polymerizable monomer 2
0 to 78.9 parts by weight, (b) 0.1 to 10 parts by weight of a vinyl monomer having a reactive silyl group and copolymerizable with the above (a) radically polymerizable monomer, (c) above ( a) Copolymer obtained by copolymerizing 1 to 20 parts by weight of a radical-polymerizable silicone macromonomer copolymerizable with a radical-polymerizable monomer and (d) 20 to 50 parts by weight of (meth) acrylonitrile. After providing a film made of coalesced on the substrate surface,
The coating is peeled off from the substrate.

As the "radical-polymerizable monomer" used for the above-mentioned (a) monomer, methyl (meth) acrylate,
Ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic acid 2
-Ethylhexyl, lauryl (meth) acrylate, alkyl (meth) acrylate such as stearyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylic acid Examples thereof include perfluoroalkyl, glycidyl (meth) acrylate, (meth) acrylic acid esters such as N, N-diethylaminoethyl (meth) acrylate, vinyl acetate, vinyl propionate, styrene, and α-methylstyrene. Only one of these may be used, or two or more thereof may be used in combination. In particular, it is preferable to use at least one selected from (meth) acrylate having an alkyl group having 1 to 12 carbon atoms and styrene from the viewpoint of copolymerizability, film physical properties and the like.

The above-mentioned (a) monomer has a glass transition temperature (Tg) of 0 to 30 ° C. (more preferably, a copolymer of the above-mentioned (a) monomer and the (d) monomer which will be described in detail later. Is 5 to 2
It is preferable that the kind and the use ratio are such that the temperature becomes 5 ° C.). Here, the lower limit of Tg is set to 0 ° C. because Tg is 0.
This is because if the temperature is lower than 0 ° C, the film becomes too soft at room temperature (about 20 to 25 ° C), and the film may be stretched to lower the peeling workability or the film may be torn. Also,
The upper limit of Tg is set to 30 ° C., because if Tg exceeds 30 ° C., the coating becomes too hard at room temperature, and the coating may be broken during peeling or coating debris may remain on the substrate. Is. The “glass transition temperature (T
“G)” refers to Tg as a calculated value obtained from the Tg of a homopolymer of each of the monomers constituting the (a) monomer and the (d) monomer and the copolymerization ratio of each of these monomers. The copolymerization amount of the monomer (a) is 20 to 7
It is 8.9 parts by weight (preferably 35 to 60 parts by weight).
This is because if the copolymerization amount of the (a) monomer is less than 20 parts by weight, Tg tends to be excessively high, so that the film may become too hard, and if the copolymerization amount exceeds 78.9 parts by weight, the film may become too hard. This is because the strength of is likely to be insufficient.

The above-mentioned monomer (b) is used as a cross-linking component, and has the effect of imparting strength to the film made of the copolymers (a) to (d). In addition, since the (b) monomer is cross-linked after the coating on the surface of the base material to form cross-linking points in the resin, the particles are “held” by the polymer chains in the film, This has the effect of improving the particle removal performance. Examples of the reactive silyl group in the monomer (b) include compounds represented by the following chemical formula 1.
The following are mentioned.

[0013]

## STR1 ## _{-Si (OR) 3 ···· (1} ) -Si (OR) n (CH 3) 3-n ···· (2) -SiCl 3 ···· (3) -Si ( OR) _n Cl _3-n (4) (wherein R is an alkyl group and n is 1 or 2)

Of these, compounds having an alkoxysilyl group are preferably used because they can be crosslinked at room temperature. Examples of such compounds include vinylmethyldimethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyl. Diethoxysilane etc. can be mentioned. Only one of these may be used, or two or more thereof may be used in combination.

The copolymerization amount of the above-mentioned (b) monomer is 0.1 to 1
The amount is 0 parts by weight (preferably 0.5 to 5 parts by weight). The lower limit of the copolymerization amount was set to 0.1 part by weight so that the copolymerization amount was 0.
This is because if the amount is less than 1 part by weight, the effect of improving the performance of removing particles is small, and the elongation of the film at the time of peeling becomes large, so that the peeling workability is deteriorated. Further, the upper limit of the amount of copolymerization is set to 10 parts by weight, because when the amount of copolymerization is more than this, the coating becomes hard, and the coating may be broken at the time of peeling or coating fragments may remain on the substrate. Because there is.

The above-mentioned (c) macromonomer is a compound having a siloxane group exhibiting releasability and a radically polymerizable group in one molecule. For example, a methacryloxy-terminated polysiloxane (trade name of Chisso Co., Ltd. Silaplane 0711 ", trade name" Macromonomer AK-32 "," Macromonomer AK-5 "manufactured by Toagosei Co., Ltd.)
Can be used. Here, as the molecular weight of the (c) macromonomer, a number average molecular weight of 1,000 to 20 is used.
000 is preferable. This is because if the number average molecular weight is less than 1000, the siloxane chain is short, and it is difficult to sufficiently obtain the effect of improving the peeling property. On the other hand, when the number average molecular weight exceeds 20,000, the copolymerizability decreases,
Further, the viscosity at the time of copolymerization is also increased, which is not preferable.

The copolymerization amount of the above (c) macromonomer is 1
To 20 parts by weight (preferably 5 to 20 parts by weight). When the copolymerization amount is less than 1 part by weight, the effect of improving the peeling property cannot be sufficiently obtained. On the other hand, if the amount of copolymerization exceeds 20 parts by weight, the strength of the film is lowered, and the film may be stretched to lower the peeling workability or the film may be torn.

The above-mentioned (d) monomer (meta)
Acrylonitrile has a function of strengthening the film by copolymerization. The copolymerization amount of (meth) acrylonitrile is 20 to 50 parts by weight (preferably 30 to 50 parts by weight).
And If the amount of copolymerization is less than 20 parts by weight, the effect of improving the toughness of the film cannot be sufficiently obtained. When the amount of copolymerization exceeds 50 parts by weight, (meth) acrylonitrile having a relatively low polymerization reactivity tends to remain as an unreacted monomer in the obtained polymerization liquid. When a film is formed from such a coating liquid containing a large amount of unreacted (meth) acrylonitrile, there is a problem that the unreacted (meth) acrylonitrile remains after the film is peeled off to contaminate the surface of the substrate. Furthermore, when a film is formed from a solution of this copolymer in an organic solvent, when the copolymerization amount of (meth) acrylonitrile increases, the viscosity increases with respect to the solid content concentration, resulting in a decrease in workability during film formation. Therefore, the copolymerization amount of (meth) acrylonitrile is 50 parts by weight or less.

In order to form a film on the surface of the substrate in the present removing method, an organic solvent solution of a copolymer obtained by copolymerizing the above (a) to (d), for example, the above (a) to (( d)
A polymer solution obtained by copolymerizing the above in an organic solvent may be applied to the surface of the base material, or an emulsion in which this copolymer is dispersed may be applied. In these cases, the releasable film is formed by removing the organic solvent or water after applying the coating liquid on the surface of the base material. During or after the formation of the film, crosslinking is carried out by the reactive silyl group contained in the monomer (b) in the film. Further, the copolymers of (a) to (d) above may be applied as they are, that is, in a state containing no organic solvent or water. However, when it is applied as an emulsion, the surface of the substrate is easily contaminated by the surfactant, and when the copolymer is applied as it is, the viscosity tends to be high, which lowers the workability of application and causes heating during application. It is most preferable to apply as an organic solvent solution because it may be necessary. Furthermore, the coating is not limited to coating, and the coating may be formed on the surface of the substrate by spraying the coating liquid in a mist or by immersing the substrate in the coating liquid.

Further, in this removing method, the above (a)
Polymers having good compatibility with the copolymers (d) to (d), for example, polyvinyl acetate, polystyrene, polyether, polyester when the monomer (a) is an alkyl (meth) acrylate. You may form a film using what blended etc. In this case, (a) above
The amount of the polymer other than the copolymers (d) to (d) used is 20 parts by weight or less (preferably 1 to 15 parts by weight) based on 100 parts by weight of the copolymers (a) to (d). Furthermore,
As long as it does not remain after the film is peeled off, a preservative, a thickener, a defoaming agent, a colorant and the like can be added and used as necessary.

According to the removing method of the present invention, the monomer (b) is copolymerized to have high particle removal performance and strength, and the component (c) is copolymerized to have good releasability. A tough film is obtained by copolymerizing the monomer (d). Since this film has a good balance between the adhesion to the surface of the substrate and the toughness of the film, the work of peeling the film from the substrate can be carried out smoothly. Further, the copolymer used in the present removal method is different from the conventional technique of blending a water repellent or a release agent, etc., and a silicone macromonomer as a release property improving component is chemically bonded to a polymer chain. Therefore, the peelability can be improved without contaminating the surface of the base material.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to Examples and Comparative Examples. According to the following polymerization procedure, Table 1
The monomer shown in 1 was polymerized to obtain a solution of a copolymer in an organic solvent. [Polymerization procedure] 400 g of ethyl acetate was added to a 1000 ml flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel.
And azobisisobutyronitrile (AIBN) 0.5m
ol% was added, and 172 g of the monomer was gradually added dropwise at 75 ° C. in a nitrogen atmosphere over 40 minutes to perform polymerization. After 3 hours from the start of dropping the monomer, the flask was cooled to stop the polymerization.

[0023]

[Table 1]

In Table 1, as the silicone macromonomer 1 *, the product name "Silaplane 0711" (molecular weight 1000) manufactured by Chisso Corporation was used.
As the vinyl monomer 2 * having a silyl group, trimethoxysilylpropyl methacrylate (manufactured by Shin-Etsu Chemical Co., Ltd.,
The product name “KBM503”) was used. In addition, compounding agent 3
* Is a product name “Liquid Silicone KP-322” manufactured by Shin-Etsu Chemical Co., Ltd., and the numerical values in the table are the actual addition amount with respect to 100% by weight of the polymerization liquid.

Next, in Comparative Example 2, a mixture of a polymerization liquid and a compounding agent was used as a coating liquid, and in other Comparative Examples and Examples, the polymerization liquid was used as it was as a coating liquid to form a film on a silicon wafer having a diameter of 8 inches. Formed. Here, on the silicon wafer, in order to evaluate the particle removal performance, about 2000 silicon particles having a diameter of about 0.2 μm were preliminarily adhered substantially uniformly. The method for forming the film is shown below. [Film forming method] At room temperature, 200 rps after dropping an appropriate amount of coating liquid on a silicon wafer having a diameter of 8 inches
The silicon wafer was rotated for 5 seconds to coat and dry the coating liquid to obtain a film having a film thickness of 10 to 11 μm. After that, the coating was crosslinked by leaving it at room temperature for several minutes.

On the film thus obtained, one end of a commercially available adhesive tape was attached, and the other end of this adhesive tape was pulled upward to conduct a peeling test of the film from the wafer surface. From the results of this peeling test, the peeling property of the film, the strength, and the film removing workability when peeling from the wafer were evaluated. Further, three points on the surface of the wafer after peeling the coating film were observed with an optical microscope of 1000 magnifications, and the number of residual particles present in these three visual fields was compared with that before the coating was formed to obtain the particle residual rate. In addition, these three fields of view
Three points were selected at equal intervals on the circumference of a virtual circle having a diameter of 4 inches and having the same center as the silicon wafer.
Furthermore, the presence or absence of organic substances remaining on the wafer surface was examined by measuring the infrared spectrum of the wafer surface. Table 2 shows the evaluation results. The peelability, film strength and film removal workability are ◎: very good, ○: good, △: somewhat poor, △
It was displayed in 5 stages: ~ x: considerably bad, x: bad. Furthermore, the copolymerization ratio of acrylonitrile, butyl acrylate and methyl methacrylate and the Tg of each homopolymer
Table 2 also shows Tg calculated from the above.

[0027]

[Table 2]

As can be seen from Table 2, in all of Examples 1 to 7, the peeling property, the film strength and the film removing workability were good, the particle removing performance was high, and the wafer was not contaminated. On the other hand, in Comparative Example 1 in which only acrylic acid alkyl ester was used as the monomer, the coating could not be peeled off by the above method because the adhesion to the wafer was too high. Therefore, the film strength and the presence or absence of wafer contamination have not been evaluated. In Comparative Example 2 in which silicone oil was added to Comparative Example 1, the peeling property was improved, but the film strength was low, and the film was greatly stretched at the time of peeling, resulting in poor film removal workability. Moreover, the silicon oil remained after the peeling and contaminated the wafer surface.

Further, as can be seen from the comparison of Examples 1 to 3, when the copolymerization amount of acrylonitrile is in the range of 20 to 50% by weight, the film strength increases as the copolymerization amount increases. However, the workability of removing the film of Example 2 was the best because the film became slightly hard. When the copolymerization amount of acrylonitrile is less than 20% by weight (Comparative Example 5), the film strength is low and the film stretches during peeling, resulting in poor film removal workability. On the other hand, when the proportion of acrylonitrile in the monomer exceeded 50% by weight (Comparative Example 6), the polymerization reactivity was low and a large amount of the monomer remained, so that the evaluation was not performed. Further, in Comparative Example 4 in which the silicone-based macromonomer was not used, the film could not be peeled off by the above method because the adhesion to the wafer was too high. Furthermore, Comparative Examples 7 and 8 and Example 4,
As can be seen from the comparison with Nos. 2 and 5, when the copolymerization amount of the silicone macromonomer is less than 1% by weight (Comparative Example 7), the effect of improving the releasability is insufficient, and the copolymerization amount exceeds 20% by weight. (Comparative Example 8) The film strength decreased.

In Comparative Example 3 in which the vinyl monomer having a reactive silyl group was not used, the film strength was low and the film elongation during peeling caused the film removal workability to be somewhat poor. Further, as can be seen from the comparison between Comparative Example 9 and Examples 6, 2, and 7, when the copolymerization amount of the vinyl monomer having a reactive silyl group is less than 0.1% by weight, the effect of improving the film strength is unsatisfactory. Was enough. On the other hand, in Comparative Example 10 in which the copolymerization amount of the vinyl monomer exceeds 10% by weight, although the film strength is improved, the film becomes too hard, so that part of the film breaks during peeling and remains on the wafer. There was a problem in film removal workability. Further, as can be seen from the comparison between Example 6 and Examples 2 and 7, even if the copolymerization amount of this vinyl monomer is 0.1% (Example 6), the particle residual rate is 2% or less, No problem, but 1
By increasing the copolymerization amount in the range of up to 0% by weight (Examples 2 and 7), the particle residual rate could be further reduced. This is because the reactive silyl group of the vinyl monomer has an effect of retaining particles in the film when forming cross-linking points in the resin, so that the retained particles are reliably removed from the wafer surface. It is thought to be because.

The present invention is not limited to the specific embodiments described above, but may be variously modified within the scope of the present invention in accordance with the purpose and application. For example, the removal of particles on a silicon wafer has been described in the above embodiments, but the removal method of the present invention is also useful for the purpose of removing particles from the surface of another inorganic material, resin, metal or the like.

[0032]

According to the removal method of the present invention, "(meth) acrylonitrile" for increasing film strength and "releasability" for "radical polymerizable monomers" such as (meth) acrylic acid alkyl ester are improved. The base material is a film made of "silicone-based macromonomer" and a copolymer obtained by copolymerizing "vinyl monomer having a reactive silyl group" at a predetermined ratio, which enhances film strength and particle removal performance. Particles are removed by providing on the surface and peeling this film from the substrate. Since the film used in the present removal method is composed of the above-mentioned copolymer, it has a good balance between the adhesion to the substrate surface and the toughness of the film, so that the film peeling operation can be carried out smoothly, and the film It has an advantage that the substrate surface is less contaminated after peeling.

Claims (3)

[Claims] 1. A radically polymerizable monomer (a) 20 to 7
8.9 parts by weight, (b) 0.1 to 10 parts by weight of a vinyl monomer having a reactive silyl group and copolymerizable with the (a) radically polymerizable monomer, (c) the above (a) Obtained by copolymerizing 1 to 20 parts by weight of a radical-polymerizable silicone-based macromonomer copolymerizable with a radical-polymerizable monomer, and (d) 20 to 50 parts by weight of at least one of acrylonitrile and methacrylonitrile. A method for removing particles on a surface of a base material, which comprises providing a surface of a base material with a coating film made of a copolymer and then peeling the coating film from the base material. 2. The method for removing particles on the surface of a substrate according to claim 1, wherein the monomer (a) is at least one of acrylate and methacrylate having an alkyl group having 1 to 12 carbon atoms. 3. The type of the (a) monomer and the (d) monomer used to obtain the copolymer and the ratio of use thereof are the same as the (a) monomer and the ( The method for removing particles on the surface of a base material according to claim 1 or 2, wherein the type and the usage ratio thereof are such that the glass transition temperature of the copolymer d) is 0 to 30 ° C.