JP2661951B2 - Radiation curable adhesive tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a semiconductor device which cuts a wafer on which a pattern is formed after each wafer process in a process of manufacturing various semiconductors for each pattern. The present invention relates to an adhesive tape for fixing a semiconductor wafer, which is used when the wafer is divided.

(Prior Art) Conventionally, in performing a dicing process of cutting and separating a semiconductor wafer on which a circuit pattern is formed into element pieces, the semiconductor wafer is previously adhered to an adhesive tape and fixed, and then the semiconductor wafer is elementally rotated by a rotary round blade. Direct pickup that cuts along the shape, slightly widens the gap between elements by radially stretching the adhesive tape for fixing, then pushes up this element piece with a needle etc. and picks up from the adhesive tape with air tweezers etc. The formula was taken.

In the above method, at the time of cutting the semiconductor wafer using the rotary round blade, 2 kg /
Cleaning water under a water pressure of about ² cm ² is discharged onto the rotating round blade and the semiconductor wafer. For this reason, the element fixing adhesive force at the time of dicing processing must be strong enough to withstand the cutting impact force of the rotating round blade and at the same time to withstand the water pressure of the washing water. In this sense, if the element fixing adhesive force is strong, The stronger the better. But,
If the adhesive strength for fixing the element is too strong, it is difficult to pick up the element from the adhesive tape, and the element may be damaged.
That is, the element fixing adhesive force at the time of dicing and at the time of pickup must be controlled in accordance with the size of the element piece. Since the adhesive strength of the adhesive tape does not change during dicing and pick-up, it is necessary to set the adhesive force according to the size of the element piece so that the element does not scatter during dicing and does not damage the element during pick-up. is there. In addition, in the case of LSI elements having a size of 25 mm ² or more, such as LSI elements with an increased degree of integration in recent years, the adhesive strength for fixing each element becomes too large, making it difficult to pick up from an adhesive tape, and the direct pickup described above. There was a problem that was not applicable.

In order to solve this problem, a support that transmits radiation, for example, light such as ultraviolet light, or ionizing radiation such as an electron beam, and an adhesive having a property of being cured by irradiation of radiation applied to the support. With the adhesive tape for fixing the semiconductor wafer consisting of the agent layer, the element fixing adhesive force at the time of dicing is strongly adhered, and after the semiconductor wafer is cut and separated into small pieces, radiation is applied from the support side to form the radiation-curable adhesive layer. By hardening, the adhesive tape for fixing semiconductor wafers, which greatly reduces the adhesive strength for fixing the element and can easily pick up a large element of, for example, 25 mm ² or more, regardless of the size of the element piece, Proposed.

These proposals relate to an adhesive tape for fixing a semiconductor wafer in which a radiation-curable adhesive is coated on a radiation-transmissive support, and the radiation-curable compound contained in the adhesive is cured by irradiation with radiation to form an adhesive. It is based on the principle that the agent is given a three-dimensional network structure and its flowability is significantly reduced. Such an adhesive tape is disclosed in
-1996956, JP-A-60-201642, JP-A-61-28572
And JP-A-62-10180.

(Problems to be Solved by the Invention) However, the surface properties of a semiconductor wafer to be bonded to such a radiation-cured, radiation-curable pressure-sensitive adhesive tape are not limited to those that have been subjected to a mirror-finished or grinding process of silicon alone, or those subjected to an etching process. Absent. In addition to these adherend surfaces, there are specially treated surfaces in which a silicon surface is coated with a metal such as gold, silver, titanium, nickel or the like or a mixture thereof by a vapor deposition method or the like.

With conventional radiation-curable pressure-sensitive adhesive tapes, the adherence of silicon alone is slightly affected by the surface roughness of the adherend, but simply by three-dimensional networking of the adhesive layer after irradiation. The fluidization of the pressure-sensitive adhesive was prevented, and the fixing power of the film could be reduced. However, the three-dimensional networking reaction of the pressure-sensitive adhesive layer after radiation irradiation does not sufficiently occur on the specially treated surface, or the pressure-sensitive adhesive layer adheres to the specially treated surface after radiation irradiation, and the element is completely peeled off (pickup). There is a problem of not being able to do so. The specially treated surface usually has the color of the metal being coated, but may be grayed or black for some reason.

The specially treated surface that has been discolored in this way prevents the radiation-curable pressure-sensitive adhesive itself from absorbing radiation that is sufficient to absorb radiation and cause the radiation-curable pressure-sensitive adhesive tape to sufficiently reduce the element fixing adhesive force. Would. Conventionally, it has been considered that the element fixing adhesive strength is hardly reduced on the special treatment surface due to the above-mentioned reason. As a solution to this problem, it has been proposed to add a silica powder, an alumina powder, or a silica-alumina powder which diffuses radiation to the radiation-curable pressure-sensitive adhesive layer as disclosed in JP-A-62-153375. However, according to the study of the present inventors, even in such a radiation-curable pressure-sensitive adhesive tape, not only does the element-fixing adhesive strength on the specially treated surface not decrease, but also the electric power of the element itself is reduced by the metal powder in the radiation-curable pressure-sensitive adhesive. It has been confirmed that this has an adverse effect on the mechanical properties.

As described above, the element fixing adhesive strength after irradiation is significantly changed depending on the state of the bonding surface of the element pieces, which causes a problem that the workability of the pickup is deteriorated and the productivity of the element is reduced. Become.

The present invention solves the above-mentioned problems while taking advantage of the radiation-curable pressure-sensitive adhesive tape as it is, that is, even if the pressure-sensitive adhesive tape bonding surface is a specially treated surface, the element fixing adhesive force is sufficiently reduced by irradiation. It is an object of the present invention to provide a radiation-curable pressure-sensitive adhesive tape that can be used.

(Means for Solving the Problems) The present inventors have conducted various studies in order to overcome the drawbacks of the conventional radiation-curable pressure-sensitive adhesive tape, and as a result,
Special treatment in which a metal surface such as gold or silver, titanium, nickel or the like or a mixture thereof is coated on the silicon surface by vapor deposition by adding an ion sequestering agent to the radiation-curable acrylic adhesive. It has also been found that the surface is cured by irradiation with radiation to form a three-dimensional network structure and, at the same time, shows a stable drop in the element fixing adhesive force. Based on this finding, the present invention has been completed.

That is, the present invention, on a radiolucent substrate, 100 parts by weight of an acrylic pressure-sensitive adhesive, 5-500 parts by weight of a compound having a carbon-carbon double bond, and 0.01 to 20 parts by weight of a nitrogen-containing heterocyclic thiol compound as an ion-sequestering agent. The present invention provides a radiation-curable pressure-sensitive adhesive tape formed by forming a radiation-curable pressure-sensitive adhesive layer containing a part.

The acrylic pressure-sensitive adhesive used in the present invention is a homopolymer having an acrylic acid or methacrylic acid ester as a main structural unit, or acrylic acid or methacrylic acid or an ester thereof or an acid amide thereof and other copolymerizable comonomers. Or a mixture of these polymers. As its monomers and comonomers, for example, alkyl esters of acrylic acid or methacrylic acid, such as methyl esters, ethyl esters, butyl esters, 2-ethylhexyl esters, octyl esters, glycidyl esters, hydroxymethyl esters,
Examples include 2-hydroxyethyl esters, hydroxypropyl esters, and amides and N-substituted amides of acrylic acid or methacrylic acid, such as N-hydroxymethylacrylamide or methacrylamide. If necessary, a compound containing a crosslinking agent such as a polyisocyanate compound or an alkyl etherified melamine compound can be used.

The compound having a carbon-carbon double bond used in the radiation-curable pressure-sensitive adhesive of the present invention is a radiation-polymerized monomer, oligomer, or polymer, such as acrylate, methacrylate, cyanurate, and isocyanurate. Specific examples include dipentaerythritol hexaacrylate, acrylates such as acrylate oligomers such as urethane acrylate oligomers, methacrylates, and cyanurate or isocyanurate compounds such as tris-2-acryloxyethyl isocyanurate, alone or in combination. It may be a mixture. Furthermore, in order to favorably lower the adhesive strength for fixing the element after irradiation, radiation-curable silicone acrylate or silicone methacrylate may be added to the adhesive.

In the present invention, it is an essential requirement that the radiation-curable pressure-sensitive adhesive layer contains a nitrogen-containing heterocyclic thiol compound as an ion-sequestering agent. Ion sequestering agents react with metal ions. As a preferred example of the nitrogen-containing heterocyclic thiol compound as the ion sequestering agent in the present invention, a triazine thiol compound is used. The nitrogen-containing heterocyclic thiol compound prevents the polymerization initiator and the radiation-curable compound contained in the adhesive of the radiation-curable pressure-sensitive adhesive tape stuck to the specially treated surface from being deteriorated by metal ions from the specially treated surface, Even if the laminated body is left without irradiation for a long period of time without radiation, it exerts an action of causing a polymerization reaction to sufficiently reduce the element fixing adhesive force by irradiation.

The triazine thiol compound has a thiol group, but since this group is bonded to a triazine ring having a high electronegativity, it is much more stable than a general thiol compound, and a small piece of the element due to dissociation of the thiol group. There is no influence such as deterioration of electrical characteristics on the surface.

In the present invention, the amount of the ion sealant added is 0.01 to 20 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the acrylic pressure-sensitive adhesive.

In the present invention, acrylate, methacrylate, cyanurate, isocyanurate and the like are used as the compound having a carbon-carbon double bond. Among them, it is particularly preferable to use a cyanurate compound or an isocyanurate compound. This is because the rate of decrease in adhesive strength after irradiation is particularly large, and an excellent radiation-curable adhesive can be obtained.

The cyanurate or isocyanurate compound is
It is a compound having a triazine ring or an isotriazine ring in the molecule and further having at least two radiation-polymerizable carbon-carbon double bonds, and may be a monomer, an oligomer or a mixture thereof. A compound having a triazine ring or an isotriazine ring can be generally synthesized by a conventional cyclization reaction using a halocyan compound, a dianiline compound, a diisocyanate compound or the like as a raw material. Furthermore, a radiation polymerizable carbon-carbon double bond-containing group such as a vinyl group,
A compound used in the present invention can be obtained by introducing a functional group containing an acryloxy group or a methacryloxy group.

In the present invention, there is no particular limitation on the cyanurate or isocyanurate compound except for the above points, but the carbon-carbon double bond-containing group introduced into the triazine ring or the isotriazine ring has a so-called rigid molecular structure, for example, an aromatic ring heterocyclic compound. Those not containing a node ring group or the like are desirable. The reason for this is that if these compounds impart excessive rigidity to the radiation-polymerizable compound, the pressure-sensitive adhesive of the present invention is excessively embrittled by radiation curing. Accordingly, the bonding group between the carbon-carbon double bond and the triazine ring or isotriazine ring preferably contains a group having a high atomic free rotation. Illustrative of these groups are aliphatic groups such as an alkylene group and an alkylidene group, which include -O-, -OCO-, -COO-, -NH
It may have a CO-, -NHCOO- bond or the like. When this bonding group is bonded to the triazine ring via -O-, at least one of the three alkylene groups, alkylidene groups and the like bonded to -O- preferably has 2 or more carbon atoms.

Specific examples of these cyanurate or isocyanurate compounds include 2-propenyl di-3-butenyl cyanurate, 2-hydroxyethyl bis (2-acryloxyethyl) isocyanurate, tris (acryloxyethyl) isocyanurate and tris (Methacryloxyethyl) isocyanurate, bis (2-acryloxyethyl) 2-{(5-acryloxyhexyl) -oxy} ethyl isocyanurate, tris (1,3-diacryloxyisopropyl-oxycarbonyl-n-hexyl) )
Isocyanurate, tris (1-acryloxy-3-methacryloxyisopropyl-oxycarbonylamino-
n-hexyl) isocyanurate and the like.

The number of radiation-polymerizable carbon-carbon double bonds per repeating unit of the monomer or oligomer of the cyanurate compound or isocyanurate compound used in the present invention is usually preferably at least 2, more preferably 2 to 6. Is good. If the number of these double bonds is less than 2, a sufficient degree of crosslinking to lower the adhesive strength by irradiation is not obtained, and if it exceeds 6, the embrittlement of the adhesive after radiation curing is excessive. Sometimes.

The compounding amount of the cyanurate compound or the isocyanurate compound in the radiation-curable pressure-sensitive adhesive is usually 5 to 500 parts by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive. If the compounding amount is too small, three-dimensional network formation by irradiation of the radiation-curable pressure-sensitive adhesive becomes insufficient, and it is not possible to control the flow inhibition of the acrylic pressure-sensitive adhesive, so that the element can be easily picked up. This is not preferable because the adhesive strength for fixing the element does not decrease to a certain extent. Conversely, if the compounding amount is too large, the plasticizing effect on the acrylic pressure-sensitive adhesive is large, and sufficient element fixing adhesive force can be obtained to withstand the cutting impact force by the rotating round blade during dicing or the water pressure of the washing water. Disappears.

In the present invention, a photoinitiator and a polymerization accelerator may be added to the radiation-curable pressure-sensitive adhesive layer, if necessary, as well as known tackifiers, softeners, antioxidants, pigments, and the like, if necessary.

When the radiation-curable pressure-sensitive adhesive tape of the present invention is cured by ultraviolet irradiation, a photopolymerization initiator, for example, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethyl oxixantone, Benzyl dimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethyl phenyl propane and the like can be used in combination. By adding one or more of these to the pressure-sensitive adhesive layer, the curing reaction can proceed efficiently even if the curing reaction time or the amount of ultraviolet irradiation is small, and the element fixing adhesive strength can be reduced.

The radiation-transmitting substrate used in the present invention is preferably plastic, rubber, or the like, and is not particularly limited as long as it transmits radiation. However, when the radiation-curable pressure-sensitive adhesive is cured by irradiating ultraviolet rays, it is necessary to use a material having good light transmission as the substrate. Examples of polymers that can be used as such a substrate include:
Polyethylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-
Α-olefin homopolymer or copolymer such as vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomer or a mixture thereof , Polyvinyl chloride, vinyl chloride-ethylene copolymer,
Vinyl chloride-vinyl acetate copolymer, vinyl chloride-based polymer or copolymer such as vinyl chloride-ethylene-vinyl acetate copolymer, vinyl fluoride-ethylene copolymer, vinylidene fluoride-ethylene copolymer, Examples include fluorine-based polymers such as FEP and PEA, and engineering plastics such as polyethylene terephthalate, polymer carbonate, and polymethyl methacrylate. The shape of the support is generally a sheet or a film. The thickness of the support is not particularly limited, but is preferably about 10 to 200 μm.

Provided on this sheet or film-like support,
The thickness of the radiation-curable pressure-sensitive adhesive layer is not particularly limited, but usually 2 to 50 μm is appropriate.

(Examples) Hereinafter, the present invention will be described in more detail based on examples.

Example 1 100 parts by weight of an acrylic pressure-sensitive adhesive (copolymer of 2-ethylhexyl acrylate and n-butyl acrylate), 3 parts by weight of a polyisocyanate compound (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.), and tris as an isocyanurate compound 60 parts by weight of 2-acryloxyethyl isocyanurate and 3 parts by weight of Disnet-DB (trade name, manufactured by Sankyo Kasei Co., Ltd.) as a triazine thiol compound, and 1 part by weight of α-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator Was added and mixed to prepare a radiation-curable pressure-sensitive adhesive. This adhesive is coated on one side of a 70 μm-thick polyethylene terephthalate film with an adhesive layer
Coating was performed so as to have a thickness of 20 μm, followed by drying by heating to obtain a radiation-curable pressure-sensitive adhesive tape.

Attach a 5 inch diameter silicon wafer to the above radiation-curable adhesive tape in a dark place not exposed to ultraviolet rays
After standing for 168 hours (one week), the adhesive strength before and after the irradiation of ultraviolet rays was measured based on JIS-Z0237. (90 ° peeling, peeling speed 50mm / min, the following examples and comparative examples are based on this method.) At this time, the surface condition of the wafer to be bonded to the adhesive tape is a special state in which gold is deposited on the silicon surface. Treated surface. The UV lamp used was a high pressure mercury lamp of 80 w / cm, and the irradiation time was 10 seconds.

Comparative Example 1 In Example 1, except that the triazine thiol compound was not added to the radiation-curable pressure-sensitive adhesive composition,
A radiation-curable pressure-sensitive adhesive tape was prepared in the same manner as described above, and the pressure-sensitive adhesive strength before and after the irradiation of the specially-treated lamination surface was measured.

Example 2 A radiation-curable pressure-sensitive adhesive tape was prepared in the same manner as in Example 1, except that 60 parts by weight of dipentaerythritol hexaacrylate was used instead of the isocyanurate compound in the radiation-curable pressure-sensitive adhesive composition. Then, the adhesive strength before and after the irradiation of the ultraviolet rays to the specially processed bonding surface was measured.

Comparative Example 2 In Example 2, a radiation-curable pressure-sensitive adhesive tape was prepared in the same manner as in Example 2 except that the triazine thiol compound was not added to the radiation-curable pressure-sensitive adhesive composition, and before and after ultraviolet irradiation on the specially-processed bonding surface. The adhesion was measured.

The test results of the radiation-curable pressure-sensitive adhesive tapes prepared in the above Examples and Comparative Examples are shown in Table 1 below.

(Effect of the Invention) As is clear from the above test results, the radiation-curable pressure-sensitive adhesive tape of the present invention has a radiation-curable pressure-sensitive adhesive composition, an adhesive and a radiation-curable compound, and a nitrogen-containing heterocyclic thiol compound as an ion-sequestering agent. Is added, so even if the surface condition of the adhesive tape such as a semiconductor wafer is a specially treated surface such as a metal-deposited surface, the radiation-irradiation will sufficiently reduce the element-fixing adhesive strength. In addition, there is an excellent effect that the element pieces can be favorably picked up from the radiation-curable pressure-sensitive adhesive tape without generation of adhesive residue or the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C09J 7/02 JLE C09J 7/02 JLE H01L 21/301 H01L 21/78 M

Claims (1)

(57) [Claims] 1. An acrylic pressure-sensitive adhesive on a radiolucent substrate.
100 parts by weight, a compound having a carbon-carbon double bond 5 to 500
A radiation-curable pressure-sensitive adhesive tape comprising a radiation-curable pressure-sensitive adhesive layer containing 0.01 to 20 parts by weight of a nitrogen-containing heterocyclic thiol compound as an ion-sequestering agent.