JPS6279649A - Dicing method for semiconductor - Google Patents

Abstract

PURPOSE:To prevent paste from scattering and adhering to a blade during a dicing process and to weaken its adhesive force for easier pickup of semiconductor elements during a segmenting process by a method wherein a light-curing adhesive tape is used and exposed to optical energy that is projected in two separate steps. CONSTITUTION:For the prevention of an adhesive agent from scattering, a wafer (a) is installed on the adhesive surface of a dicing tape (j) that is a transparent resin sheet (c) with one of its surfaces covered with a UV-curing adhesive agent (b). A masking sheet (d) is pasted to the rear surface of the dicing tape (j), so configured as to allow a portion of the adhesive agent (b) to cure when exposed to a UV beam (k). The UV beam (k) comes in from the side of the masking sheet (d) to travel through a transparent section (e) positioned along a line for the separation of semiconductor elements, and hardens the portion of the adhesive agent (b). A dicing blade (g) is actuated for a cut into a hardened portion (h). The masking sheet (d) is removed and then another step of UV projection is accomplished from the rear surface of the dicing tape (j). The adhesive agent (b) is completely cured in this process, which reduces the force of its adhesion with a wafer and facilitates the semiconductor element pickup process to follow.

Description

[Detailed description of the invention] [Industrial application field] The present invention is to cut the f-conductor into eight parts.

It concerns a method of separation.

[Conventional technology]

Currently, the methods for dividing a conductor wafer into individual elements include fixing the wafer with adhesive tape, etc., and cutting the wafer completely to the back side with a dicing blade, or cutting the wafer leaving several microns to the rA side. .

The method for completely cutting a round surface is to cut the die sink plate down to the adhesive of the adhesive tape. This has the disadvantage that the adhesive adheres to the plate, shortening the life of the plate 7P, and the adhesive fi11 scatters and adheres to the element surface, lowering the yield.

In addition, the method of dicing with several microns left on the back side of the wafer requires the remaining portion to be broken by external stress, which has the disadvantage that the shape of the broken wafer becomes non-uniform and that productivity is poor.

First of all, if the adhesive strength of the adhesive tape is weak, the element r will scatter during die sinking, and if it is strong, the element r will become difficult to pick up, and the initial adhesive strength should be selected according to the size of the element f. [Problems to be solved by the invention] In view of the following problems, the present invention aims to improve the productivity of semi-dedicated elements. To provide a dicing method that does not shorten the life of a dicing blade in a dicing method that cuts to the back surface of a wafer, prevents adhesion of elements due to glue scattering, and facilitates element separation, that is, pick-up performance. be.

[Means for solving problems]

The present inventors used a photocurable adhesive tape in a dicing method that cuts the backside of a wafer and irradiated it with light in two stages to prevent glue from scattering during dicing and from adhering to the blade, and to further prevent element separation. The present invention was completed after discovering that the adhesive strength can be reduced during printing and the pick-up properties can be made easier.

That is, in the present invention, a wafer on which semiconductor elements are formed is fixed on a photocurable adhesive tape, and a dicing blade is used to dice the semiconductor element f.
In the method of completely cutting the back side of the wafer sequentially along the splitter fixed line, the adhesive in the area along the semiconductor element m + fixed line is cured with light, the element r is cut, and then the adhesive is applied to the entire surface. This dicing method is characterized by curing with light and separating the element f.

This method first uses an ultraviolet curing adhesive (b) as shown in Figure 1.
) is coated on one side of a transparent resin sheet (c), and the wafer (a) is attached to the adhesive side of tie sink tape ('').

At this time, the adhesive force must be strong enough to prevent the elements from scattering during dicing, and the resin sheet may be a semi-rigid or rigid film such as PVC, PP, or PET that transmits light. is preferably selected appropriately depending on the working method.

Next, a mask sheet (d) that cures only the adhesive portion along the line where the conductor elements are to be separated is attached to the back side of the die sink tape. Although it is necessary to prepare in advance a transparent part (e) that transmits light and a part (f) that does not transmit light along the fixed line of this mask sheet, it is possible to create it by a conventional method.

As a method of pasting, a method can be selected as appropriate, such as a method of coating a mask sheet or a dicing tape with a transparent temporary adhesive and a method of pasting it, or a method of fixing and sticking the ends using a jig. Next, light is irradiated from the mask sheet side to partially cure the adhesive.

As the light to be irradiated, electron beams and ultraviolet rays can be used. A xenon lamp, a mercury lamp, sunlight, a carphone arc, etc. can be used as the ultraviolet irradiation method.

After partially hardening the outer edge along a fixed line, the partially hardened part (
h) Cut. The hardness of the adhesive in the cured part during dicing must be hardened to such an extent that the adhesive does not adhere to the dicing blade.

Furthermore, as shown in Figure m3, after the mask sheet is peeled off, ultraviolet rays are irradiated from the back of the dicing tape again to harden the adhesive over the entire surface and reduce its adhesion to the cube. After that, it is picked up with tweezers and a semiconductor element is manufactured.

The ultraviolet curable adhesive mentioned here refers to a copolymerizable Qi H1 monomer containing an ethylenic double bond and a functional group.
A photoreactive vinyl compound and a photosensitizer are blended into a copolymer with a photoreactive vinyl compound and a photosensitizer having at least one associative carbon-carbon double bond in the molecule.

Examples of the '111 body having an ethylenic double bond used in the present invention include (1) methyl acrylate, ethyl acrylate, and butyl acrylate.

Alkyl acrylates such as 2-ethylhexyl acrylate and methyl methacrylate, alkyl methacrylates such as n-butyl methacrylate, (2) vinyl esters such as vinyl acetate, (3) acrylonitrile,
rllfi1 selected from acrylamide, styrene, etc.
One type of these may be used, or two or more sleeves may be used in combination.

Copolymerizable monomers having functional groups to be copolymerized with these include (meth)acrylic acid, itaconic acid, maleic acid, 2- and droxyethyl (meth)acrylate, glycidyl methacrylate, N-methylol (meth) One or more types such as acrylamide may be used.

In this invention, the method for introducing at least one polymerizable carbon-carbon double bond into a molecule is to introduce a group capable of reacting with a functional group such as a carboxyl group, a hydroxyl group, or a glycidyl group present in the above-mentioned copolymer. What is necessary is to copolymerize a photoreactive @q substance containing an associative carbon-carbon bond.

The photoreactive vinyl compound used in the present invention is a polyfunctional compound having at least one, preferably two or more, polymerizable carbon-carbon double bonds that undergo a photopolymerization reaction in the molecule. Examples include neobentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

Examples of the photosensitizer used in the present invention include benzoins such as hengein and benzoin methyl ether, and benzophenones such as hensifhenone and P-chlorohensifhenone.

The ultraviolet curable pressure-sensitive adhesive of the present invention containing each of the above components is applied to one side of a transparent resin sheet to a coating thickness of 5 to 1 after drying.
A photocurable pressure-sensitive adhesive tape can be obtained by coating the adhesive so that it has a 0.00 scale coating.

This will be explained in detail in Examples below.

(Reference example) Production of ultraviolet curable adhesive 2-Ethylhexyl acrylate 100 parts Ethyl acrylate 55 parts Methyl acrylate 50 parts Crisidyl methacrylate 10 parts Toluene 215 parts Benzoyl peroxide 0.1 part Replace the above with nitrogen Pour into a flask and stir while stirring.
The reaction was carried out at 5°C for about 10 hours.

To this were added 5 parts of acrylic acid and 4 parts of tetradecyldimethylhenzyl ammonium chloride, and the mixture was reacted at 105° C. for about 6 hours while blowing air to introduce a carbon-carbon double bond.

To 100 parts of this polymerization product, 25 parts of neopentyl glycol diacrylate, 5 parts of benzoin methyl ether
A UV-curable pressure-sensitive adhesive was obtained.

In this example, a UV-curable adhesive layer with a thickness of 20μ was provided on one side of an axially stretched polyolefin sheet with a thickness of 200μ, and the adhesive strength without UV irradiation was 500g/25nm (T peel strength).
The size of the semiconductor element is 10mmx on the dicing tape.
A silicon wafer of lO+nm and a cutting line width of 50 μm was laminated, and a PET resin mask sheet of 10 μm aligned in P was closely attached to the back of the dicing tape using a jig, and irradiated with a mercury lamp for 1 Osec.

Thereafter, cutting was performed along fixed lines with a dicing saw (DISCO DAD-3MI).

After cutting, the mask sheet was peeled off from the dicing tape, and the back side of the dicing tape was irradiated again with a mercury lamp for 20 seconds, and the elements were picked up and separated using vacuum tweezers.

As shown in Table 1, there was no adhesive on the dicing blade, and there was no adhesive on the surface of the element. In addition, in the pick-up separation process using vacuum tweezers, l element f
It could be easily separated without leaving any residue.

Comparative Example-1 The dicing tape used in Example-1 was used, the silicon wafer used in Example-1 was attached, and the adhesive was cured by irradiating the back of the dicing tape with a mercury lamp for 1 osec without using a mask film. I let it happen. Thereafter, it was cut using a dicing saw and picked up and separated using vacuum tweezers.

As shown in Table 1, the adhesive hardened over the entire surface during dicing and the adhesive strength decreased, causing scattering of elementary Y- during dicing.

Comparative Example-2 One side of a soft PVC sheet with a thickness of 80μ was coated with a regular adhesive to a thickness of 20μ. Using a dicing tape with an adhesive force of 500g/25+nm, the silicon wafer used in Example-1 was prepared as described above. It was cut with a dicing saw and picked up and separated with vacuum tweezers.

As shown in Table 1, adhesion of adhesive to the dicing blade and element surface was observed, and the blade was replaced after 100 hours.

Furthermore, the adhesive strength during pickup was strong and elements with <60% could not be picked up.

Comparative Example 3 Using a dicing tape having the same structure as that used in Comparative Example 2 with an adhesive force of 20 g/25 mm, the silicon wafer used in Example 1 was cut with the dicing saw described above, and then the elements were picked up and separated.

As shown in Table 1, the results showed that there was adhesive adhesion to the dicing blade and the element surface, and when die sinking
% of elementary f was scattered.

[Brief explanation of drawings]

Figure 1 shows a case in which a square is fixed to the adhesive side of a dicing tape and light is irradiated through a mask sheet pasted on the back side of the tape, and Figure 2 shows a case in which the cured adhesive part is cut with a dicing blade. FIG. 3 shows a case in which the mask sheet is then peeled off, light is irradiated again from the back side of the dicing tape, and the guide rod tip f is picked up. a: silicon wafer, b = ultraviolet curing adhesive, CIJt
material film, d: mask film, e: light transmitting part,
f: light blocking part, g: dicing blade,
'h: hardened adhesive part, i: vacuum tweezers, j: dicing tape, k: UV light.

Claims (1)

[Claims] In this method, a wafer on which semiconductor elements have been formed is fixed on a photocurable adhesive tape, and a dicing blade is used to completely cut the wafer along the line where the semiconductor elements are to be separated, sequentially to the back side of the wafer. A dicing method characterized by cutting the elements after curing with light, and further curing the adhesive over the entire surface with light to separate the elements.