JPH08274059A - Foreign substance removal adhesive tape for precision electronic component - Google Patents

Abstract

PURPOSE: To remove a foreign substance, which adheres to a semiconductor wafer, a glass substrate or the like, at a high removal rate using an ultraviolet cured adhesive tape. CONSTITUTION: As a foreign substance removal adhesive tape 1 for a precision electronic component, an adhesive tape, which is formed by providing an adhesive layer 12, which is cured by ultraviolet irradiation and has a property of changing its molecular structure into a three-dimensional reticulate structure, on a support film 11 and is formed using a support film of an ultraviolet transmittance of 50% or higher as the support film 11, is used.

Description

Detailed Description of the Invention

[0001]

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 the manufacturing process of precision electronic parts such as semiconductors and liquid crystal display panels.

[0002]

2. Description of the Related Art As the density and integration of LSIs increase, and the density and size of liquid crystal display panels increase, the presence of foreign substances such as dust and metal impurities on semiconductor wafers and glass substrates. ) Has come to have a great influence on product yield and product reliability. For example, a foreign substance existing on the surface of a semiconductor wafer (circuit pattern forming surface) causes a disconnection or a short circuit of a circuit when the circuit is formed.
Also, the back surface of the semiconductor wafer (the surface opposite to the circuit pattern surface)
The foreign matter existing in the surface causes the focus to be deviated in the exposure process at the time of forming the circuit, and when transferred to the surface of the adjacent wafer, it causes the disconnection of the circuit and the short.

Therefore, in the LSI manufacturing process, efforts are being made to improve the level of cleanliness in the manufacturing process and the level of wafer cleaning technology, and various cleaning technologies have been proposed and implemented. Especially, the cleaning process is about 2
It accounts for 0 to 30%, and is the key to yield and reliability improvement.
It is a point. The same applies to the manufacturing process of liquid crystal display panels 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, the wafer cleaning method includes wet cleaning (using ultrapure water, chemical solution, etc.) and dry cleaning (U
V ozone, O ₂ plasma, etc.), and in general, wet cleaning is frequently applied because of its good balance of versatility and economy. However, a problem in wet cleaning is re-adhesion of foreign matter removed from the wafer by cleaning to the wafer, and especially foreign matter adhering to the back surface of the wafer becomes a significant pollution source. Also, since wet cleaning requires a drying process, there is a problem of wafer contamination in the drying process as well.

As a cleaning method for compensating the disadvantages of wet cleaning, dry cleaning methods (UV ozone, O ₂ plasma, etc.) are being advanced, and advantages such as reduction of redeposition of foreign matters and omission of a drying step are 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
Japanese Patent Application Laid-Open No. Hei 1-135574, etc., a method of using an adhesive tape to remove foreign matter adhering to the surface of a semiconductor wafer, a glass substrate, etc. by adsorbing it to the adhesive layer surface of the tape. Is proposed. Since this tape method can be said to be a kind of dry cleaning, it is possible to avoid the problem of reattachment of foreign matter in wet cleaning and the problem of contamination in the drying process, and further, it is possible to avoid other problems such as UV ozone and O ₂ plasma. It is expected that the ability to remove foreign matter will be further improved compared to dry cleaning.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have examined this tape construction method and, in particular, use a UV-curable adhesive tape, which is adhered onto a semiconductor wafer and then UV-cured. If the peeling operation is performed later, the adhesive can sufficiently adapt to the foreign matter on the wafer due to the plastic deformability and the high adhesiveness at the time of sticking, and at the time of peeling, the adhesive on the wafer will be low-adhesive by UV curing. It has been found that a smooth peeling operation can be performed without causing any inconvenience such as remaining 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 modified so that foreign substances adhering to a semiconductor wafer or a glass substrate can be removed at a higher removal rate. It is intended to be removed.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, as a UV-curable pressure-sensitive adhesive tape, a supporting film on which a pressure-sensitive adhesive layer is to be provided has excellent UV rays. By using a transparent material, the pressure-sensitive adhesive layer is quickly and efficiently cured by the irradiation of ultraviolet rays from the support film side, which further improves the peeling workability and allows foreign matter to adhere to semiconductor wafers. The present invention has been completed, knowing that is effectively absorbed and removed.

That is, according to the present invention, a pressure-sensitive adhesive layer having a property of being cured by irradiation of ultraviolet rays to have a three-dimensional reticulation of a molecular structure is provided on a supporting film, and the ultraviolet transmittance of the supporting film is 50%. The present invention relates to an adhesive tape for removing foreign matter of precision electronic parts, which is characterized as described above.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a foreign matter removing adhesive tape of the present invention. 1 is adhesive tape,
An adhesive layer 12 is provided on a support film 11, and a separator 13 is superposed on the adhesive layer 12.

The support film 11 has an ultraviolet transmittance of 50% or more, which is determined by the material, thickness, film forming means, etc.
Preferably 60% or more, more preferably 75% or more,
Most preferably, 90% or more is used. When a material having such an ultraviolet transmittance is used, the curing reaction of the pressure-sensitive adhesive layer is efficiently carried out, and good results are obtained in improving the peeling workability by shortening the irradiation time and further increasing the foreign matter removal rate.

The material of the support film is polyethylene, polypropylene, ethylene-propylene copolymer,
Ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate,
Examples include plastics such as polyethersulfone, polyetherketone, polyphenylene sulfide, polymethylpentene, polyetherimide, polyparabanic acid, polyketoneimide, polyamideimide, polyacetate, polycarbonate, polyvinyl chloride and the like. . The thickness of the support film is usually 10 to 1,000 μm.

The pressure-sensitive adhesive layer 12 has an adhesive force under normal conditions, that is, a pressure-sensitive adhesive property, and has a property of being cured by irradiation of ultraviolet rays so that the molecular structure becomes a three-dimensional network. Various polymers such as resin, silicone resin, fluorine resin, rubber (natural rubber and synthetic rubber) are used as base polymers, and a polymerizable compound and, if necessary, a polymerization initiator are added to the composition. It is a thing. The above-mentioned 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 usually has a molecular weight of 10 Those of 1,000 or less are preferably used. The amount used is 10 to 1,000 parts by weight, preferably 80 to 1,000 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 tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol pentaacrylate, dipentaerythritol monohydroxypentaacrylate. , Dipentaerythritol hexaacrylate, 1,4-butanediol diacrylate,
Examples thereof include polyethylene glycol diacrylate, commercially available oligoester acrylate, urethane acrylate, and epoxy acrylate. 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, and examples thereof include isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, chlorothioxanthone, dodecyl thioxanthone, dimethyl thioxanthone and diethyl thioxanthone. , Acetophenone diethyl ketal, benzyl dimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethyl phenyl propane, etc., among which the one that matches the characteristic wavelength of the ultraviolet light source used Is used.

Even if these polymerization initiators are one kind,
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 with respect to 100 parts by weight of the polymerizable compound. If necessary, an amine compound such as triethylamine, tetraethylpentamine, dimethylaminoethanol or the like may be used together with this polymerization initiator as a polymerization accelerator.

A pressure-sensitive adhesive layer 12 having such a composition
Is a pressure-sensitive adhesive composition containing the above base polymer and a polymerizable compound and, if necessary, a polymerization initiator.
It can be formed by applying it on 1 and then performing a crosslinking treatment by heating or the like, or by adhering the pressure-sensitive adhesive layer formed on the separator 13 by the same method as described above on 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 carried out if necessary. For example, in the case of an acrylic resin adhesive, an acrylic resin having a cross-linkable functional group in its molecule is used as a base polymer, A cross-linking agent composed of a polyfunctional compound having a functional group capable of reacting with this functional group, such as a polyisocyanate compound or a polyepoxy compound, may be preliminarily blended in the pressure-sensitive adhesive composition.

The adhesive strength of the adhesive layer 12 is JIS Z-0.
18 for silicon wafers measured according to 237
0 degree peeling adhesive strength (at room temperature, peeling speed 300 mm / min)
Is usually 500 g or more / 20 mm width, preferably 700-2
000 g / 20 mm width, and the same adhesive strength as above after being cured 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 from the viewpoint of preventing contamination during storage or distribution of the pressure-sensitive adhesive tape 1. However, it is peeled off and removed when the above-mentioned pasting is used.
The separator 13 is usually a flexible thin sheet made of paper (dust-free paper), plastic film, metal foil or the like, and if necessary, surface-treated with a release agent to impart releasability.

In the present invention, the adhesive tape 1 having the above structure
As an example of applying the above to the cleaning step in the manufacturing process of the precision electronic component, for example, a method of adsorbing and removing foreign matter adhering to the semiconductor wafer will be described. First, FIG.
As shown in FIG. 3, the adhesive tape 1 is attached to the entire surface 2a and / or the back surface 2b of the semiconductor wafer 2 so that the surface of the adhesive layer is sufficiently adapted to the foreign matter 3 on the wafer. This may be done by any method such as pressing with a hand roller and then leaving it for several minutes. Here, since the pressure-sensitive adhesive layer 12 has plastic deformability and has the large pressure-sensitive adhesive force, the foreign matter 3 on the wafer 3 during the above-mentioned bonding operation.
Effectively adsorb and hold.

After sticking in this way, the adhesive tape 1
A peeling operation of peeling off from the end of the tape 1 is performed. Prior to this peeling operation, ultraviolet rays are irradiated from the side of the support film 11 of the tape 1. Ultraviolet rays generally have a wavelength of 400 nm
In the following, as the 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, etc. are used.

Here, since the ultraviolet transmittance of the supporting film 11 is as high as 50% or more and the problem of ultraviolet shielding by this film is small, the pressure-sensitive adhesive layer 12 can be quickly and effectively exposed by irradiation from the light source. Upon curing, the molecular structure is three-dimensionally reticulated to change the elastic modulus, resulting in being hard and exhibiting the low adhesive strength. Therefore, if the above peeling operation is performed in such a state, the peeling can be performed smoothly, the wafer surface is hardly damaged or the adhesive residue does not cause contamination, and the foreign matter on the semiconductor wafer 2 is adhered by the curing. Agent layer 1
It will be strongly and surely adsorbed on the two surfaces.

By this method, foreign matters on the semiconductor wafer 2 can be adsorbed and removed at a high removal rate as compared with the conventional dry cleaning, as well as the wet cleaning and the method using the already proposed adhesive tape. In particular, it is possible to obtain a high removal rate of about 80% or more for removing foreign matters having a size of 0.2 μm or more.

By cleaning and removing the foreign matter on the semiconductor wafer at a high removal rate in this manner, the occurrence of circuit disconnection, shots, and exposure defects at the time of circuit formation is reduced, and the yield of semiconductor devices finally manufactured is reduced. And reliability is greatly improved. This is the same even when applied to the cleaning step in the manufacturing process of other precision electronic components such as a liquid crystal display panel, and the same effect as in the case of the above semiconductor is obtained. Also,
From the standpoint of global environmental protection, 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, It can also contribute significantly to environmental conservation.

[0028]

As described above, according to the pressure-sensitive adhesive tape for removing foreign matter of the present invention, by using a support film having an excellent UV transparency as the support film on which the UV-curable pressure-sensitive adhesive layer is provided, When it is attached to an adherend such as a semiconductor wafer, and the support film side irradiates it with ultraviolet rays, the adhesive layer cures quickly and efficiently, and as a result, the operation of peeling the adhesive tape from the adherend. Easy, and can adsorb and remove foreign matter on the adherend with a high removal rate, yield of precision electronic parts such as semiconductor devices and liquid crystal display panels,
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 environment conservation can be obtained.

[0029]

EXAMPLES Next, examples of the present invention will be described to more specifically describe. In the following, "parts" means "parts by weight". The ultraviolet transmittance refers to the transmittance of ultraviolet rays 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 cross-linking agent composed of a polyisocyanate compound, and 100 parts of dipentaerythritol hydroxypentaacrylate as a polymerizable oligomer.
Parts, 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 corona-treated surface was coated with the solution of the above-mentioned acrylic pressure-sensitive adhesive and heat-crosslinked at 120 ° C. for 5 minutes. A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 20 μm was produced. The adhesive strength of this adhesive tape to a silicon wafer (mirror surface) is measured according to JIS Z-0237. 18
0 degree peeling adhesive strength (at room temperature, peeling speed 300 mm / min)
The width was 980 g / 20 mm. Also, from the support film surface side, ultraviolet rays (wavelength 365 nm, 1,000 mJ / cm
² ) was irradiated and the adhesive strength was measured in the same manner.
The width was / 20 mm.

A 5-inch silicon wafer with no foreign matter having a size of 0.2 μm or more (a mirror without a circuit pattern)
A wafer is passed through a predetermined process (ion implantation process) to adhere foreign matter, and adhered to the mirror surface using a laser surface inspection device [LS-5000 manufactured by Hitachi Electronics Engineering Co., Ltd.]. The number of foreign matters having a size of 0.2 μm or more was counted. In addition, in order to count the foreign matters adhering to the front and back of the wafer, the same inspection was performed in two cases in which the mirror surfaces were reversed.

As a foreign matter cleaning test, the adhesive tape produced by the above method was applied to the mirror surface of the silicon wafer on which the foreign matter had been adhered as described above by a hand roller (rubber elastic roller).
La) was applied and left for 3 minutes. Then, ultraviolet rays (wavelength 365 nm, 1,000
After irradiating with mJ / cm ² ), the adhesive tape was peeled off and washed. After this cleaning, the number of foreign matters having a size of 0.2 μm or more attached to the mirror surface was counted again using the laser surface inspection device. The foreign matter removal rates on the front and back surfaces of the silicon wafer were calculated from the number of foreign matter after cleaning by the attaching and peeling operations and the number of foreign matter before cleaning. In this foreign matter cleaning test, a series of operations were performed in a class 10 clean room (temperature 23 ° C., humidity 60%). The results are as shown in Table 1.

Example 2 A supporting film having a thickness of 50 μm and an ultraviolet transmittance of 81
%, A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 20 μm was produced in the same manner as in Example 1 except that polyethylene terephthalate film was used. Using this adhesive tape,
Thereafter, a foreign matter cleaning test (measurement of foreign matter removal rate) was performed in the same manner as in Example 1. The results are as shown in Table 1. The adhesive force to the silicon wafer (mirror surface) is measured according to JIS Z-0237.
0 degree peeling adhesive strength (at room temperature, peeling speed 300 mm / min)
And has a width of 1,020 g / 20 mm, and ultraviolet rays (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.
The width was / 20 mm.

Example 3 A supporting film having a thickness of 50 μm and an ultraviolet transmittance of 95
A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 20 μm was produced in the same manner as in Example 1 except that 100% of methyl pentene copolymer (TPX) film was used. Using this adhesive tape, a foreign matter cleaning test (measurement of foreign matter removal rate) was performed in the same manner as in Example 1. The results are as shown in Table 1. Silicon wafer (mirror surface)
The adhesive force for peeling is a 180 degree peeling adhesive force (normal temperature, peeling speed 30 measured according to JIS Z-0237).
It has a width of 055 g / 20 mm at 0 mm / min) and ultraviolet rays (wavelength 365 nm, 1,000) from the support film surface side.
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%
A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 20 μm in the same manner as in Example 1 except that the above polyarylate film was used.
I made a cup. Using this adhesive tape, Example 1 will be described below.
A foreign matter cleaning test (measurement of the foreign matter removal rate) was performed in the same manner as in. The results are as shown in Table 2. In addition,
Adhesive strength to silicon wafer (mirror surface) is JIS
180 degree peeling adhesive strength (normal temperature, peeling speed 300 mm / min) measured according to Z-0237, 1,040 g
/ 20 mm width, and irradiated with ultraviolet rays (wavelength 365 nm, 1,000 mJ / cm ² ) from the support film surface side,
Similarly, the adhesive strength was measured and found to be 820 g / 20 mm width.

Comparative Example 2 A supporting film having a thickness of 50 μm and an ultraviolet transmittance of 15
%, A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 20 μm was produced in the same manner as in Example 1 except that a polyethylene naphthalate film was used. Using this adhesive tape,
Thereafter, a foreign matter cleaning test (measurement of foreign matter removal rate) was performed in the same manner as in Example 1. The results are as shown in Table 2. The adhesive force to the silicon wafer (mirror surface) is measured according to JIS Z-0237.
0 degree peeling adhesive strength (at room temperature, peeling speed 300 mm / min)
And has a width of 1035 g / 20 mm, and ultraviolet rays (wavelength 365 nm, 1,000 mJ / cm from the side of the support film).
² ) was irradiated and the adhesive strength was measured in the same manner.
The width was g / 20 mm.

Comparative Example 3 A supporting film having a thickness of 38 μm and an ultraviolet transmittance of 45 was used.
%, A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 20 μm was produced in the same manner as in Example 1 except that a polyethylene naphthalate film was used. Using this adhesive tape,
Thereafter, a foreign matter cleaning test (measurement of foreign matter removal rate) was performed in the same manner as in Example 1. The results are as shown in Table 2. The adhesive force to the silicon wafer (mirror surface) is measured according to JIS Z-0237.
0 degree peeling adhesive strength (at room temperature, peeling speed 300 mm / min)
The width is 1,120 g / 20 mm, and ultraviolet rays (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.
The width was g / 20 mm.

[0039]

[Table 1]

[0040]

[Table 2]

As is clear from the results of Tables 1 and 2 described above, according to the adhesive tapes of Examples 1 to 3 of the present invention, about 80% to 80% of the foreign matter adhered to the front surface and the back surface of the silicon wafer was detected. It can be adsorbed and removed at a higher removal rate, but Comparative Example 1
It can be seen that the adhesive tapes of to 3 are considerably inferior in the foreign matter removing effect.

The 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 matter, and finally obtained semiconductor devices were manufactured. As a result of collecting the yields, it was found that the adhesive tapes of Examples 1 to 3 had a yield of about 5 to 8% higher than that of the adhesive tape of Comparative Example 2.

Separately from this, Examples 1 to 1 of the present invention
When the adhesive tapes of 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 matters, the yield of the finally obtained liquid crystal display panel was tabulated, and Example 1 was obtained. It was also confirmed that the adhesive tapes of Nos. 3 to 3 have a yield as high as about 12 to 20% as compared with the adhesive tape of Comparative Example 2.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an adhesive tape for removing foreign matter of the present invention.

FIG. 2 is a cross-sectional view showing a method for removing foreign matter by using the foreign matter-removing adhesive tape of the present invention.

[Explanation of symbols]

 1 Adhesive Tape 11 Supporting Film 12 Adhesive Layer 13 Separator 2 Semiconductor Wafer 3 Foreign Material Adhering to Semiconductor Wafer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C09J 7/02 JKF C09J 7/02 JKF JKL JKL JKZ JKZ

Claims (1)

[Claims] 1. A support film is provided with an adhesive layer having a property of being cured by irradiation of ultraviolet rays and having a three-dimensional network structure by being irradiated with ultraviolet rays, and the ultraviolet transmittance of the support film is 50% or more. Adhesive tape for removing foreign matter from precision electronic parts.