JPS6128572A - Pressure-sensitive adhesive sheet and method for using the same - Google Patents

Abstract

PURPOSE:To provide a pressure-sensitive adhesive sheet which is suitable for use in sticking semiconductor wafers and whose adhesion is variable, by forming a layer of a radiation-curable, pressure-sensitive adhesive consisting of a pressure- sensitive adhesive and a radiation-polymerizable oligomer on a substrate. CONSTITUTION:10-90pts.wt. acrylic pressure-sensitive adhesive is mixed with 90-10pts.wt. radiation-polymerizable urethane acrylate oligomer to prepare a radiation-curable, pressure-sensitive adhesive. A layer 2 of the adhesive is formed on a substrae 1 to obtain the desired pressure-sensitive adhesive sheet A. In the use of the sheet A, the sheet is placed in such a manner that the upper side is the adhesive layer 2. A semiconductor wafer B to be processed is sticked on the adhesive layer and is processed. The layer 2 is irradiated with a radiation 4 to polymerize and cure the radiation-polymerizable oligomer, whereby the adhesion of the adhesive layer 2 is reduced, and wafer chips b are picked up.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an adhesive sheet that is used by being attached to semiconductor wafers such as silicon wafers and gallium arsenide wafers, objects to be painted such as automobiles, and the like.

(Prior art) Conventionally, for example, when masking or dicing a semiconductor wafer, acrylic-based adhesive sheets have been used to adhere to a semiconductor wafer on the surface of a base material such as vinyl mide or polypropylene. A pressure-sensitive adhesive sheet is used, which is formed by forming a coating layer of a pressure-sensitive adhesive such as a pressure-sensitive adhesive.

To carry out the series of expanding, picking up, and mounting processes, an adhesive sheet is attached to the semiconductor wafer in advance, and the wafer is diced, expanded, and cleaned while it is still attached.

After each drying process, each chip t of the wafer is
- For the mounting process, chips are picked up from the adhesive sheet, but the picked up chips are often contaminated with adhesive. In order to prevent this contamination, it has been proposed to reduce the amount of adhesive applied to the adhesive sheet by applying it partially rather than over the entire surface, but this reduces the amount of adhesive attached to the total number of chips. However, chips that are fixedly held by an adhesive generally have a lower adhesive force to prevent the adhesive from adhering to the wafer and contaminating it when it is picked up. With the adhesive,
This time, the adhesion holding power for one wafer from dicing to expanding tends to be insufficient, resulting in the problem of wafer chips falling off during these processing steps.

Therefore, when the adhesive sheet is attached to a wafer as an adhesive cocoon, it is desirable to be able to sufficiently hold the wafer with a relatively large adhesive force, while at the same time ensuring that the adhesive does not remain on the chip when it is picked up. It is desirable that there is no strong adhesive force.

In addition, conventional adhesive sheets have been applied to the surfaces of automobiles and other objects to be treated.
When spray painting with an anti-inflammatory agent, adhesive is used as a masking agent on the area to be protected from the paint, and when it is removed after painting, the adhesive often remains on the surface where it was applied. There was an inconvenience that required cleaning treatment.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks of conventional pressure-sensitive adhesive sheets, and in order to satisfy the above-mentioned conflicting demands, the present invention provides a pressure-sensitive adhesive sheet with variable adhesive strength and a conventional pressure-sensitive adhesive sheet for processing objects. The present invention provides a method for using the adhesive without residual contamination.

(Means for Solving the Problems) The adhesive sheet of the present invention is characterized in that a coating layer of a radiation-curable adhesive comprising an adhesive and a radiation-polymerizable oligomer is formed on a base material surface. In addition, the method of using the adhesive sheet of the present invention is to apply a pressure-sensitive adhesive sheet having a coating layer of a radiation-curable adhesive consisting of an adhesive and a linearly polymerizable oligomer formed on the substrate surface to the surface of the object to be treated. After carrying out a predetermined treatment in this state, the adhesive is irradiated with radiation to reduce its adhesive strength. (Embodiment) Next, an embodiment of the present invention will be described.

The shape of the pressure-sensitive adhesive sheet of the present invention is tape-like. No matter the shape, such as a label. The base material is preferably one that has low electrical conductivity, water resistance, and heat resistance, and a synthetic resin film is particularly suitable. As described later, the adhesive sheet of the present invention is used after being irradiated with 1, E, U, V, etc., so in the case of E, E, irradiation, the base material is
Although it does not need to be transparent, if U, V, irradiation is used, the material must be transparent.

In addition, if it is necessary to perform an expanding process after dicing a semiconductor wafer, a synthetic resin film that is stretchable in both the length and width directions, such as vinyl chloride or polypropylene, is used as the base material, as in the past. In the case of semiconductor processing that does not require such an expanding treatment, masking of automobiles, etc., any base material without extensibility can be used.

A feature of the present invention is that the adhesive applied to the above-mentioned substrate surface is a radiation-curable adhesive (hereinafter simply referred to as "curable adhesive" for convenience), which is a composition of an adhesive and a radiation-polymerizable oligomer. The purpose is to form a coating layer.The coating may be applied over the entire surface or in partial dots.

As the adhesive component constituting the hardening adhesive, an acrylic adhesive is preferable, and specifically, an acrylic adhesive selected from homopolymers and copolymers having acrylic ester as the main monomer unit. These include copolymers with other functional monomers, and mixtures of these polymers. For example, as the monomer acrylic ester, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate,
to methacrylic acid-2-: )” o xyxyl, etc.
Also, for example, acrylic acid may be used instead of the above-mentioned methacrylic acid. Examples of radiation polymerizable oligomers include compounds having a carbon-carbon double bond, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate,
N-methylol acrylamide, polyethylene glycol acrylate, etc. and polyvalent isocyanate compounds, such as 2, . 4-) Synthesized from lylene diisocyanate, 2,6-lylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, etc. A urethane group-containing urethane acrylate oligomer is preferred. Therefore, when the compounding ratio of the acrylic adhesive and the urethane acrylate oligomer is 10 to 90 parts by weight of the acrylic adhesive to 9D to 10 parts by weight of the urethane acrylate oligomer, a large initial adhesive force can be obtained. At the same time, the adhesive force after radiation irradiation is significantly reduced, and the effect that there is almost no adhesive force is highly desirable.

Incidentally, when an isocyanate curing agent is mixed into the above compounded composition, the initial adhesive strength can be increased. As the curing agent, polyvalent incyanate compounds such as 2.4-) lylene diisocyanate, 2.6-) lylene diisocyanate, 1j-xylylene diisocyanate, 1,4-xylylene diisocyanate are used. , diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,47-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicycloxylmethane-4,41 -diisocyanate, dicyclohexylmethane-2°4'-diisocyanate, lysine isocyanate, and the like.

Furthermore, in the above formulation, υ, v, and for the irradiation table, υ,
(2) When an initiator is mixed, the predetermined adhesive strength can be lowered by reducing the polymerization curing time by irradiation or the amount of U, V, irradiation.

Examples of the U and V initiators include benzoin, benzoin methyl ether, benzoin ethyl ether,
These include benzoin isopropyl ether, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, cyanatyl, β-chloroanthraquinone, and the like. In the pressure-sensitive adhesive sheet of the present invention thus obtained, the curable pressure-sensitive adhesive coating layer is generally prepared by polymerizing a release sheet treated with an appropriate silicone-based release agent or the like in accordance with a conventional method on the upper surface of the curable pressure-sensitive adhesive coating layer. Product. FIG. 1 shows an example of an adhesive sheet according to the present invention, in which (1) is a transparent synthetic resin sheet base material having extensibility, and (2) is a curable adhesive coated on its upper surface. The layer (3) is a releasable sheet (3) which is temporarily adhered and polymerized on the upper surface of the pressure-sensitive adhesive sheet A of the present invention consisting of these layers (1) +21.
) is shown.

An example of how to use the adhesive sheet shown in the first figure of the present invention is shown in the second figure.
This will be explained with reference to FIGS. 6 to 6. Figures 2 to 4 show an example of the method of using the adhesive sheet of the present invention on a semiconductor wafer, in which the releasable sheet (3) is removed from the adhesive sheet (1) A shown in the figure. As shown in the second diagram, place the curable adhesive coating layer (2) with the entire surface facing upward, and the coating layer +2
A semiconductor wafer B to be diced is polymerized and adhered to the upper surface of 7. In this pasted state, the next step is dicing.

Generally, cleaning, drying, and expanding are performed, but the curable adhesive (2) is sufficiently adhesive and retained by the adhesive it contains, so it is easy to perform predetermined dicing and prevent each chip from falling off. It is possible to carry out predetermined braking by washing, drying, and expanding.

Next, when these wafer chips b, b...0 are picked up one by one and predetermined mounting is performed, U is placed before the picking up.

The curable adhesive coating layer (2) is irradiated with radiation IIt such as V, or I, B, etc., and the radiation contained therein #J! The polymerizable oligomer is polymerized and cured. If so, apply layer (2)
The adhesion of the coating material decreases significantly, resulting in a cured coating layer with only a very small amount of adhesion remaining. FIG. 3 shows v y, or E, E before the big-up process.

The radiation 114+ of is shown transferred from the lower surface of the transparent substrate (1) to the opaque coating layer (2). Next, the chip b'6 is moved to the pick-up station shown in Figure 4, and in the usual manner, the chip b'6 to be picked up is pushed up from the bottom using the push-up needle rod (5), and in this state, it is picked up using, for example, air tweezers (6). Mount it on a predetermined base. During this pick-up process, each wafer chip b has almost its coating layer (
2) Since it is not bonded, it can be easily picked up without any adhesive contamination, resulting in good quality mounting. Of course, the above-mentioned radiation irradiation may be carried out at the pick-up station shown in FIG. The irradiation may be carried out several times; for example, for each wafer chip b to be picked up, irradiation can be performed using a radiation tube that irradiates only the back surface corresponding to the wafer chip b, thereby curing that part. After reducing the adhesive strength of the adhesive only, push up the needle rod.

(5) Push it up and pick it up.
Try to do it sequentially. In the case shown in Fig. 5, a modification of the method of use is shown, in which the push-up needle rod (5) is a hollow needle rod, and the radiation conduction path (5) that connects the inside to the radiation source (
7) is formed to double as a radiation irradiation tube, simplifying the device, and at the same time, using a push-up needle rod (5) to irradiate radiation onto the curable adhesive layer (2) on the bottom surface of the chip b where it is to be picked up. By irradiating the adhesive, the adhesive force of the area was almost reduced and the pick-up operation was shortened by pushing up the area at the same time as the scrap.

In addition, in the processing of the above-mentioned cow conductor wafer, expanding was not performed, but dicing and cleaning were performed.

Pick-up of the chips can be carried out immediately after drying, and in this case, when the adhesive strength of the adhesive coating layer is reduced by irradiation according to the present invention, the predetermined pick-up can be carried out satisfactorily.

Figure 6 shows an example in which the adhesive sheet of the present invention is used for masking in painting, and (8) shows an automobile body or other object to be painted. In this process, the pressure-sensitive adhesive sheet of the present invention (At) of the present invention is pasted in advance on a predetermined surface area (8&) that should not be painted, and coated with sufficient adhesive strength to protect it, and the coating film (9) is heated and dried. Then, radiation (4) is emitted from the outer surface of the adhesive sheet (A). In such a case, the adhesive strength of the curable adhesive coating layer (2) will suddenly and significantly decrease.
If it is peeled off from this state, the surface part (81L) of the article (8)
) had no adhesive residue or contamination.

Next, the effect of significantly reducing the initial adhesive strength when the tread sheet of the present invention is irradiated with radiation will be shown in the following test example.

Test Example 1 50 parts of acrylic adhesive (copolymer of 2-ethylhexyl acrylate and n-butyl acrylate) and urethane acrylate oligomer (trade name: Squid Beamed EX)
A mixture of 50 parts (manufactured by Dainichiseika Chemical Co., Ltd.) was coated on a 38 μm thick polypropylene film, heated and dried to form a 10 μm thick radiation-curable adhesive coating layer, and a release paper was pasted on the top surface of the mixture to form a product. And so. Remove the release paper and cut the diameter 1
A silicon wafer of 00I11 was polymerized and pasted on the top surface of the curable adhesive coating layer, and the adhesive strength was measured based on J Engineering 8-Z-0237, and it was 1350, 9/25. The effective absorbed dose of B is 2 Mr.
After ad irradiation (voltage 150KsV, current 5mA),
The adhesive strength was measured at 58, lit/25 m.
There was a significant decrease in m.

Next, the silicon wafer was peeled off, but no adhesive was observed at all. For comparison, the wafer was immediately peeled off without irradiation of the IC and B described above, but a large amount of adhesive was observed on the back surface.

Test Example 2 A mixture of 65 parts of the same acrylic adhesive as above, 35 parts of the same urethane acrylate oligomer as above, and an isocyanate curing agent (trade name BH8-8515 manufactured by Toyo Ink Co., Ltd.) was applied to a 60 μm thick polypropylene film. A coating layer of 15 μm in thickness was formed by coating and heating and drying. A silicon wafer was polymerized and adhered to the upper surface of the coating layer, and the adhesive force was measured to be 155011/25 mm.

Next, this was irradiated with JB under the same conditions as in Test Example 1, and the adhesive strength was measured after that.
There was a significant decrease in m.

Test Example 3 50 parts of the same acrylic adhesive as above, 50 parts of the same urethane acrylate oligomer as above, and U, V initiator (
A mixture of 5 parts of benzoin) was applied to a transparent vinyl chloride film with a thickness of 50 μm and dried by heating.A silicon wafer was polymerized and adhered to the upper surface of the applied layer, and the adhesive strength was measured. ji1725mm,
This was irradiated with U and V for 6 seconds (high pressure mercury lamp, 80W/
cm). At that time, the adhesive strength was reduced to 521/25 aun.

Test Example 4 Acrylic adhesive (N-butyl acrylate and 2-hydroxyethyl methacrylate) 265 parts of copolymer, urethane acrylate oligomer (trade name, Nitsuso Cure UM-1, manufactured by Shin Nisso Kako Co., Ltd.) 55 parts, isocyanate curing agent (BIB-8515) and U, (i) initiator,
(Irgacuana 651 manufactured by Ciba Geigy) was coated on a transparent polyethylene terephthalate film with a thickness of 58 μm, and a silicon wafer was polymerized and adhered to the top of the coated layer formed by heating and drying.The adhesion force at that time was measured. , il / 25 man, but this was followed by 2 seconds of U, V, irradiation (high pressure mercury lamp, SO
W/cm), the adhesive strength was 12. p/2
It dropped to 5 fights.

(Effects of the Invention) As described above, the present invention is a pressure-sensitive adhesive sheet in which a coating layer of a radiation-curable pressure-sensitive adhesive consisting of a pressure-sensitive adhesive and a radiation-polymerizable oligomer is formed on the base surface of the pressure-sensitive adhesive sheet. 1. While it is possible to adhere to the object to be treated with a relatively high desired initial adhesive force during its use, when necessary, the initial adhesive force can be significantly reduced by irradiating the adhesive sheet with radiation. If this is pasted on the surface of a semiconductor wafer or any other object to be processed, and then irradiated with radiation after the prescribed treatment, no adhesive will remain on the surface to be processed after the label is removed. First, it has the effect of eliminating the drawbacks of conventional adhesive labels and making it possible to work on objects to be processed more smoothly.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an example of the adhesive sheet of the present invention, and FIGS. 2 to 4 are cut side views of an example of how the adhesive sheet of the invention is used for semiconductor wafers. Figure 5 is a sectional view of a portion of a modified example of its usage, and Figure 6 is a 1s cut side view of an example used for masking an article to be coated. ... Radiation curable adhesive (2 types... Cured layer (3)... Peelable sheet A... Adhesive sheet of the present invention) B... Wafer b...
・Wafer chip (4)...Radiation (5)...Pushing needle rod (6)...Air tweezers (7)...
・Radiation conduction path (8)...Object to be painted (8a)...
・Masking surface part (9)...Coating film patent applicant
Fuji Shiko Co., Ltd. Representative Kin Kitamura -', 7゜, / 2 other people Figure 2 Date Figure 4 Figure 6

Claims (1)

[Scope of Claims] 1. A pressure-sensitive adhesive sheet, characterized in that a coating layer of a radiation-curable pressure-sensitive adhesive consisting of a pressure-sensitive adhesive and a radiation-polymerizable oligomer is formed on a base material surface. 2. The radiation curable adhesive is an acrylic adhesive 10~
90 parts by weight vs. 90 to 90 parts by weight of urethane acrylate oligomer
The pressure-sensitive adhesive sheet according to claim (1), comprising 10 parts by weight. 3. A pressure-sensitive adhesive sheet with a coating layer of a radiation-curable pressure-sensitive adhesive consisting of a pressure-sensitive adhesive and a radiation-polymerizable oligomer formed on the surface of the substrate is applied to the surface of the object to be treated in a prescribed manner. A method of using a pressure-sensitive adhesive sheet, which comprises irradiating the pressure-sensitive adhesive with radiation to reduce its adhesive strength after it has worn off.