JP3441836B2 - Adhesive tape for removing foreign matter from precision electronic components - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive tape for removing foreign matter, which is applied to a cleaning step in a manufacturing process of a precision electronic component such as a semiconductor and a liquid crystal display panel. . 2. Description of the Related Art As LSI densities and integrations increase, and liquid crystal display panels increase in density and screen size, foreign substances such as dust and metal impurities existing on semiconductor wafers and glass substrates have been developed. (Particle) has greatly affected product yield and product reliability. For example, foreign matter present on the surface (circuit pattern forming surface) of a semiconductor wafer causes disconnection or short-circuit of a circuit at the time of circuit formation.
Also, the back side of the semiconductor wafer (opposite the circuit pattern side)
The foreign matter present in the wafer causes the focus to be deviated in the exposure step at the time of forming the circuit, and the transfer to the surface of the adjacent wafer causes the disconnection or short circuit of the circuit. For this reason, in the LSI manufacturing process, efforts are being made to increase the level of cleanliness in the manufacturing process and the level of wafer cleaning technology, and various cleaning technologies have been proposed and implemented. In particular, the cleaning process is about 2
It accounts for 0-30%, and is the key to improving yield and reliability.
Is the point. The same can be said for the manufacturing process of the liquid crystal display panel and the manufacturing process of other precision electronic components. However, with the recent technological development, the problem of the conventional cleaning method has become apparent. For example, a wafer cleaning method includes wet cleaning (using ultrapure water, a chemical solution, etc.) and dry cleaning (U.S.A.).
V ozone, O ₂ plasma, etc.), and generally, wet cleaning is frequently applied because of its good balance between versatility and economy. However, a problem in wet cleaning is the re-adhesion of foreign matter removed from the wafer by the cleaning to the wafer. In particular, foreign matter adhering to the back surface of the wafer becomes a significant source of contamination. Further, since the wet cleaning requires a drying step, there is a problem of wafer contamination in the drying step as well. As a cleaning method for compensating for the disadvantages of wet cleaning, dry cleaning methods (UV ozone, O ₂ plasma, etc.) have been promoted, and advantages such as reduction of reattachment of foreign substances and omission of a drying step have been utilized. However, it has been found that dry cleaning does not show a sufficient ability to remove foreign substances and is not suitable for removing a large amount of contaminants. As another attempt, JP-A-48-35771 discloses
And Japanese Patent Application Laid-Open No. 1-135574 disclose a method for removing foreign substances adhering to the surface of a semiconductor wafer, a glass substrate, or the like by using an adhesive tape on a surface of the adhesive layer of the tape. Has been proposed. Since this tape method can be said to be a kind of dry cleaning, the problem of reattachment of foreign substances in wet cleaning and the problem of contamination in a drying process can be avoided. In addition, other methods such as UV ozone and O ₂ plasma can be avoided. It is expected that the ability to remove foreign substances can be further improved as compared with dry cleaning. SUMMARY OF THE INVENTION The present inventors have studied this tape method, and used an adhesive tape, particularly an ultraviolet-curing type, and stuck it on a semiconductor wafer. When the peeling operation is performed after UV curing, the plastic deformation and high adhesiveness of the pressure-sensitive adhesive make it possible to sufficiently conform to foreign substances on the wafer at the time of sticking. It has been found that a smooth peeling operation can be performed without causing inconvenience such as adhesive residue on the top, and a high foreign matter removal rate can be obtained. In the present invention, when such an ultraviolet-curing type adhesive tape is used, the tape structure is further devised so as to remove foreign substances adhering to a semiconductor wafer, a glass substrate or the like at a higher removal rate. It is intended to be eliminated. Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, as a UV-curable adhesive tape, a support film on which an adhesive layer is to be provided is provided. By using a material that has excellent ultraviolet transmittance, the adhesive layer is quickly and efficiently cured by the irradiation of ultraviolet light from the support film side, thereby further improving the peeling workability and improving the semiconductor wafer and the like. The inventor has found that adhering foreign substances are more effectively adsorbed and removed, and have completed the present invention. That is, according to the present invention, a pressure-sensitive adhesive layer having a property of being cured by irradiation with ultraviolet rays to form a three-dimensional molecular structure on a support film is provided on the support film, and the ultraviolet transmittance of the support film is 75%. The present invention relates to an adhesive tape for removing foreign matter from precision electronic components, which is characterized by the above. FIG. 1 shows an example of an adhesive tape for removing foreign matter according to the present invention. 1 is an adhesive tape,
An adhesive layer 12 is provided on a support film 11, and a separator 13 is superposed thereon. The support film 11 has an ultraviolet transmittance of 75% or more determined by the material, thickness, film forming means and the like.
Preferably, those having 90% or more are used. The use of a material exhibiting such an ultraviolet transmittance allows a curing reaction of the pressure-sensitive adhesive layer to be efficiently performed, and good results can be obtained in improving the peeling workability by shortening the irradiation time and further increasing the foreign matter removal rate. As the material of the supporting film, polyethylene, polypropylene, ethylene-propylene copolymer,
Ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate,
Plastics such as polyethersulfone, polyetherketone, polyphenylene sulfide, polymethylpentene, polyetherimide, polyparabanic acid, polyketoneimide, polyamideimide, polyacetal, polycarbonate, polyvinyl chloride, etc. . The thickness of the supporting film is usually 10 to 1,000 μm. The pressure-sensitive adhesive layer 12 has a tackiness under normal conditions, that is, a pressure-sensitive adhesive property, and has a property of being cured by irradiation of ultraviolet rays to form a three-dimensional molecular structure of a molecular structure. Various polymers such as resin, silicone resin, fluorine resin, and rubber (natural rubber, synthetic rubber) are used as base polymer, which contains polymerizable compound and, if necessary, polymerization initiator. Things. The above base
The polymer may have a carbon-carbon double bond in the molecule. The polymerizable compound is a polymerizable monomer or oligomer having two or more, preferably 3 to 6 carbon-carbon double bonds involved in the curing reaction in the molecule and having a molecular weight of usually 10 2,000 or less are preferably used. The amount used is 10 to 1,000 parts by weight, preferably 80 to 100 parts by weight, based on 100 parts by weight of the base polymer.
It can be appropriately selected within the range of 200 parts by weight. Examples of such a polymerizable compound include tetramethylol methanetetraacrylate, pentaerythritol triacrylate, pentaerythritol pentaacrylate, dipentaerythritol monohydroxypentaacrylate. , Dipentaerythritol hexaacrylate, 1,4-butanediol diacrylate,
Examples include polyethylene glycol diacrylate, commercially available oligoester acrylate, urethane acrylate, epoxy acrylate and the like. These polymerizable compounds may be used alone or in combination of two or more. The polymerization initiator may be any one capable of generating a radical upon irradiation with ultraviolet rays. Examples thereof include isopropylbenzoin ether, isobutyl benzoin ether, benzophenone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, and diethylthioxanthone. , Acetophenone diethyl ketal, benzyl dimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethyl phenyl propane, and the like. Of these, those suited to the characteristic wavelength of the ultraviolet light source used Is used. Even if one kind of these polymerization initiators is used,
Two or more kinds may be used in combination. The amount used is preferably in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the polymerizable compound. If necessary, an amine compound such as triethylamine, tetraethylpentamine, or dimethylaminoethanol may be used as a polymerization accelerator together with the polymerization initiator. The pressure-sensitive adhesive layer 12 composed of such a composition
Comprises a pressure-sensitive adhesive composition containing the above-mentioned base polymer and polymerizable compound and, if necessary, a polymerization initiator,
1 and then subjected to a cross-linking treatment by heating or the like, or by adhering the pressure-sensitive adhesive layer formed on the separator 13 in the same manner as described above to the support film 11. The thickness of the pressure-sensitive adhesive layer 12 may be appropriately determined, but is usually 5 to 100 μm. The above-mentioned cross-linking treatment is performed as necessary. For example, in the case of an acrylic resin-based pressure-sensitive adhesive, an acrylic resin having a cross-linkable functional group in a molecule is used as a base polymer. A cross-linking agent comprising a polyfunctional compound having a functional group that reacts with the functional group, for example, a polyisocyanate compound, a polyepoxy compound, or the like may be previously blended in the pressure-sensitive adhesive composition. The adhesive strength of the adhesive layer 12 is JIS Z-0.
18 for a silicon wafer measured according to 237
0 degree peeling adhesive strength (normal temperature, peeling speed 300mm / min)
500g or more / 20mm width, preferably 700 to 2,
000 g / 20 mm width, and the same adhesive strength after curing by irradiating ultraviolet rays is usually 500 g or less /
The width is 20 mm, preferably 1 to 100 g / 20 mm. The separator 13 protects the surface of the pressure-sensitive adhesive layer 12 until it is attached to a semiconductor wafer or the like in order to prevent contamination during storage and distribution of the pressure-sensitive adhesive tape 1. It is peeled and removed at the time of the above-mentioned pasting use.
The separator 13 is usually a flexible thin sheet made of paper (dust-free paper), plastic film, metal foil or the like, and is used if necessary by releasing the surface by a release agent if necessary. In the present invention, the adhesive tape 1 having the above structure is used.
As an example of applying the method to a cleaning step in a manufacturing process of a precision electronic component, for example, a method of adsorbing and removing foreign matter attached to a semiconductor wafer will be described. First, FIG.
As shown in (1), an adhesive tape 1 is stuck on the entire surface 2a and / or the rear surface 2b of the semiconductor wafer 2, and the surface of the adhesive layer is sufficiently adapted to the foreign material 3 on the wafer. This can be done by any method, for example, after pressing by a hand roller and leaving it to stand for several minutes. Here, since the pressure-sensitive adhesive layer 12 has plastic deformation properties and the large adhesive force, the foreign matter 3
Is effectively absorbed and held. After sticking in this manner, the adhesive tape 1
Before the peeling operation, the tape 1 is irradiated with ultraviolet rays from the side of the support film 11 before the peeling operation. UV light generally has a wavelength of 400 nm
In the following, as a light source, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, a xenon lamp, an excimer laser, or the like is used. Here, since the ultraviolet transmittance of the support film 11 is as high as 75% or more and the problem of ultraviolet shielding by the film is small, the pressure-sensitive adhesive layer 12 can be quickly and effectively irradiated by the light source. It hardens, changes its molecular structure into a three-dimensional network, changes its elastic modulus, and becomes hard and exhibits the low adhesive force. Therefore, if the above-mentioned peeling operation is performed in such a state, the peeling can be performed smoothly, and the surface of the wafer and the contamination due to the adhesive residue hardly occur. Agent layer 1
The two surfaces are strongly and surely adsorbed. According to this method, foreign substances on the semiconductor wafer 2 can be adsorbed and removed at a higher removal rate than conventional dry cleaning, wet cleaning, and a method using an already proposed adhesive tape. In particular, a high removal rate that can remove foreign matters having a size of 0.2 μm or more by about 80% or more can be obtained. When the foreign matter on the semiconductor wafer is washed and removed at a high removal rate in this manner, the occurrence of disconnection, short circuit, and exposure failure of the circuit at the time of circuit formation is reduced, and the yield of the finally manufactured semiconductor device is reduced. And reliability is greatly improved. This is the same even when applied to a cleaning step in a manufacturing process of another precision electronic component such as a liquid crystal display panel, and the same effects as in the case of the above-described semiconductor are exerted. Also,
From the point of view of global environmental conservation, by replacing the conventional cleaning method that consumes a large amount of pure water, chemicals, air, electric power, etc., such as wet cleaning and dry cleaning, with the tape method of the present invention described above, It can greatly contribute to environmental conservation. As described above, according to the pressure-sensitive adhesive tape for removing foreign matter of the present invention, a support film having excellent ultraviolet transmittance is used as a support film on which a UV-curable pressure-sensitive adhesive layer is to be provided. This allows the pressure-sensitive adhesive layer to be quickly and efficiently cured when applied to an adherend such as a semiconductor wafer and irradiated with ultraviolet light from the support film side. As a result, the adhesive tape from the adherend is hardened. It is easy to peel off, and can remove foreign substances on the adherend by suction at a high removal rate. The yield of precision electronic components such as semiconductor devices and liquid crystal display panels can be improved.
It can greatly contribute to the improvement of productivity and reliability. Further, compared to other conventional cleaning methods, a contribution effect in terms of global environmental protection can be obtained. Next, an embodiment of the present invention will be described in more detail. Hereinafter, "parts" means parts by weight. The ultraviolet transmittance refers to the transmittance of ultraviolet light having a wavelength of 365 nm measured by an ultraviolet spectrophotometer. Example 1 80 parts of n-butyl acrylate, 15 parts of acrylonitrile and 5 parts of acrylic acid were copolymerized in ethyl acetate by a conventional method to obtain an acrylic copolymer having a number average molecular weight of 850,000. To 100 parts of this copolymer, 3 parts of a crosslinking agent comprising a polyisocyanate compound, and dipentaerythritol hydroxypentaacrylate 100 as a polymerizable oligomer.
, And 5 parts of α-hydroxycyclohexylphenyl ketone as a photopolymerization initiator were added to prepare a solution of an acrylic pressure-sensitive adhesive. A polyethylene terephthalate film having a thickness of 125 μm and an ultraviolet transmittance of 75% was used as a support film, and the above-mentioned solution of the acrylic pressure-sensitive adhesive was applied to the corona-treated surface thereof, followed by heat crosslinking at 120 ° C. for 5 minutes. Thus, an adhesive tape having an adhesive layer having a thickness of 20 μm was prepared. The adhesive strength of the adhesive tape to the silicon wafer (mirror surface) is measured according to JIS Z-0237.
0 degree peeling adhesive strength (normal temperature, peeling speed 300mm / min)
At 980 g / 20 mm width. Also, ultraviolet rays (wavelength 365 nm, 1,000 mJ / cm)
² ) was irradiated, and the adhesive strength was measured in the same manner.
/ 20 mm width. A 5-inch silicon wafer with no foreign matter having a size of 0.2 μm or more (mirror without circuit pattern)
The wafer was passed through a predetermined process (ion implantation process) to attach foreign matter, and then adhered to the mirror surface using a laser surface inspection device (LS-5000 manufactured by Hitachi Electronics Engineering Co., Ltd.). The number of foreign substances having a size of 0.2 μm or more was counted. In order to count foreign substances adhering to the front and back of the wafer, the same inspection was performed in two cases where the mirror surface was turned upside down. As a foreign substance cleaning test, an adhesive tape prepared by the above-described method was applied to a mirror surface of a silicon wafer to which foreign substances were adhered as described above, using a hand roller (rubber elastic roller).
And then left for 3 minutes. Thereafter, ultraviolet light (wavelength 365 nm, 1,000
After irradiation with mJ / cm ² ), the adhesive tape was peeled off and washed. After this cleaning, the number of foreign substances having a size of 0.2 μm or more adhering to the mirror surface was counted again using a laser surface inspection apparatus. From the number of foreign substances after cleaning by the attaching and peeling operations and the number of foreign substances before cleaning, the foreign substance removal rates on both the front and back surfaces of the silicon wafer were calculated. In this foreign substance cleaning test, a series of operations were performed in a class 10 clean room (temperature 23 ° C., humidity 60%). The results were as shown in Table 1. Example 2 A supporting film having a thickness of 50 μm and an ultraviolet transmittance of 81 was used.
% Of a polyethylene terephthalate film, and an adhesive tape having an adhesive layer having a thickness of 20 μm was prepared in the same manner as in Example 1. Using this adhesive tape,
Thereafter, a foreign substance cleaning test (measurement of the foreign substance removal rate) was performed in the same manner as in Example 1. The results were as shown in Table 1. The adhesive strength to a silicon wafer (mirror surface) is measured according to JIS Z-0237.
0 degree peeling adhesive strength (normal temperature, peeling speed 300mm / min)
And a width of 1,020 g / 20 mm and ultraviolet light (wavelength 365 nm, 1,000 mJ / cm) from the support film surface side.
² ) was irradiated, and the adhesive strength was measured in the same manner.
/ 20 mm width. Example 3 A supporting film having a thickness of 50 μm and an ultraviolet transmittance of 95 was used.
% Of a methylpentene copolymer (TPX) film was used in the same manner as in Example 1 to prepare an adhesive tape having an adhesive layer having a thickness of 20 μm. Using this adhesive tape, a foreign substance cleaning test (measurement of the foreign substance removal rate) was performed in the same manner as in Example 1. The results were as shown in Table 1. In addition, silicon wafer (mirror surface)
The adhesive strength to 180 degrees peeling adhesive strength measured at JIS Z-0237 (normal temperature, peeling rate 30
(0 mm / min) and a width of 1,055 g / 20 mm, and ultraviolet rays (wavelength 365 nm, 1,000
mJ / cm ² ), and the adhesive strength was measured in the same manner. The result was 8 g / 20 mm width. COMPARATIVE EXAMPLE 1 A supporting film having a thickness of 50 μm and an ultraviolet transmittance of 1%
An adhesive tape having an adhesive layer having a thickness of 20 μm was prepared in the same manner as in Example 1 except that the polyarylate film was used.
Was prepared. Using this adhesive tape, the following Example 1
A foreign substance cleaning test (measurement of the foreign substance removal rate) was performed in the same manner as described above. The results were as shown in Table 2. In addition,
Adhesion to silicon wafer (mirror surface)
1,040 g in 180 degree peeling adhesive strength (normal temperature, peeling speed 300 mm / min) measured according to Z-0237
/ 20 mm width, and irradiate ultraviolet rays (wavelength 365 nm, 1,000 mJ / cm ² ) from the support film surface side,
When the adhesive strength was measured similarly, it was 820 g / 20 mm width. Comparative Example 2 As a supporting film, a thickness of 50 μm and an ultraviolet transmittance of 15 were used.
%, And an adhesive tape having an adhesive layer having a thickness of 20 μm was produced in the same manner as in Example 1 except that the polyethylene naphthalate film was used. Using this adhesive tape,
Thereafter, a foreign substance cleaning test (measurement of the foreign substance removal rate) was performed in the same manner as in Example 1. The results were as shown in Table 2. The adhesive strength to a silicon wafer (mirror surface) is measured according to JIS Z-0237.
0 degree peeling adhesive strength (normal temperature, peeling speed 300mm / min)
And a width of 1,035 g / 20 mm, and ultraviolet rays (wavelength 365 nm, 1,000 mJ / cm) from the support film surface side.
² ), and the adhesive strength was measured in the same manner.
g / 20 mm width. Comparative Example 3 The thickness of the supporting film was 38 μm, and the ultraviolet transmittance was 45.
%, And an adhesive tape having an adhesive layer having a thickness of 20 μm was produced in the same manner as in Example 1 except that the polyethylene naphthalate film was used. Using this adhesive tape,
Thereafter, a foreign substance cleaning test (measurement of the foreign substance removal rate) was performed in the same manner as in Example 1. The results were as shown in Table 2. The adhesive strength to a silicon wafer (mirror surface) is measured according to JIS Z-0237.
0 degree peeling adhesive strength (normal temperature, peeling speed 300mm / min)
And a width of 1,120 g / 20 mm, and ultraviolet rays (wavelength 365 nm, 1,000 mJ / cm) from the support film surface side.
² ), and the adhesive strength was measured in the same manner.
g / 20 mm width. [Table 1] [Table 2] As is clear from the results shown in Tables 1 and 2, according to the pressure-sensitive adhesive tapes of Examples 1 to 3 of the present invention, about 80% or less of the foreign matter adhered to the front and back surfaces of the silicon wafer. Although it can be adsorbed and removed at a higher removal rate, Comparative Example 1
It can be seen that the adhesive tapes of Nos. 1 to 3 are considerably inferior in the foreign matter removing effect. The pressure-sensitive adhesive tapes of Examples 1 to 3 and Comparative Example 2 of the present invention were applied to a semiconductor wafer manufacturing process including a cleaning step for removing foreign substances. As a result of counting the yield, it was found that the yield was increased by about 5 to 8% in the pressure-sensitive adhesive tapes of Examples 1 to 3 as compared with the pressure-sensitive adhesive tape of Comparative Example 2. Further, apart from this, Examples 1 to 4 of the present invention
When the adhesive tapes of Comparative Example 3 and Comparative Example 2 were applied to a manufacturing process of a liquid crystal display panel including a cleaning step for removing foreign substances, the yield of the finally obtained liquid crystal display panel was counted. It was also confirmed that the adhesive tapes of Nos. 1 to 3 had a higher yield of about 12 to 20% as compared with the adhesive tape of Comparative Example 2.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of an adhesive tape for removing foreign matter according to the present invention. FIG. 2 is a cross-sectional view showing a method for removing foreign matter using the adhesive tape for removing foreign matter of the present invention. [Description of Signs] 1 Adhesive tape 11 Support film 12 Adhesive layer 13 Separator 2 Semiconductor wafer 3 Foreign matter adhered to semiconductor wafer

Continuation of front page (56) References JP-A-7-45557 (JP, A) JP-A-7-29861 (JP, A) JP-A-5-179211 (JP, A) JP-A-7-1993032 (JP) , A) JP-A-63-43987 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/304

Claims (1)

(57) [Claims 1] An adhesive layer having a property of being cured by irradiation of ultraviolet rays and having a molecular structure of three-dimensional network is provided on a support film, and the ultraviolet rays of the support film are provided. An adhesive tape for removing foreign matter from precision electronic components, having a transmittance of 75% or more .