JPH04335078A - Radiation-curable self-adhesive tape - Google Patents

Abstract

PURPOSE:To obtain the title tape which causes stable decrease in the element fixing tack after irradiation with radiation, is free from poor pick up of elements, and does not exert any adverse effect on the electrical characteristics of element chips after the dicing of semiconductor wafer even when a support film made of various resins is used as a support of a radiation-curable self-adhesive tape. CONSTITUTION:0.01-10wt.% sequestering agent, for example, nitrogenous heterocyclic thiol compound is incorporated into a resin layer which forms a radiation- transmitting support film for a radiation-curable self-adhesive tape.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a semiconductor wafer fixing device used for cutting a patterned wafer into individual patterns and dividing it into semiconductor elements after the wafer process is completed in the process of manufacturing various semiconductors. Fixing adhesive tapes used to protect patterned surfaces when grinding or etching the back surface of wafers on which patterns are formed to set the thickness according to each application in the process of manufacturing various semiconductors. It is.

0002

[Prior Art] Conventionally, radiation, such as ultraviolet light,
or a support that transmits ionizing radiation such as an electron beam;
An adhesive tape for fixing semiconductor wafers has been developed, which comprises an adhesive layer coated on this support and having a property of being cured by radiation irradiation. This uses the element fixing adhesive force fixed by the adhesive layer during dicing as a strong adhesive force, and after cutting and separating the semiconductor wafer into small element pieces, radiation is irradiated from the support side to harden the radiation-curable adhesive layer. , the adhesive force for fixing the element is significantly reduced. This adhesive tape for fixing semiconductor wafers has been proposed so that it can easily pick up even large devices, for example, 25 mm@2 or more, regardless of the size of the small device pieces.

These proposals involve curing a radiation-curable compound contained in a radiation-curable adhesive coated on a radiation-transparent support by radiation irradiation to give the adhesive a three-dimensional network structure. It is based on the principle of significantly reducing fluidity. This kind of adhesive tape is
JP-A-60-196956, JP-A-60-20164
No. 2, JP-A-61-28572, JP-A-62-101
There are some disclosed in No. 80, etc.

[0004] Also, an adhesive tape for surface protection when grinding the back surface of a semiconductor wafer or the like has been proposed, which utilizes the change in adhesive strength of such a radiation-curable adhesive before and after radiation irradiation. These proposals protect the circuit pattern surface with a strong adhesive force during grinding of a wafer, etc., and reduce the adhesive force when the tape is peeled off by irradiation with radiation. As such an adhesive tape, there is one disclosed in Japanese Patent Application Laid-Open No. 189938/1983.

[0005]

[Problems to be Solved by the Invention] However, such radiation-curable adhesive tapes do not use polyvinyl chloride, polyethylene, ethylene-vinyl acetate copolymer,
A radiation-transparent material such as polypropylene or polyethylene terephthalate, which is obtained by using a film consisting of one or more resin layers of these materials and coating one side with a radiation-curable adhesive layer as described above. It is. However, it has been found that radiation-curable adhesive tapes using these film-like supports have the following problems.

[0006] Although the resin layer used as such a radiation-transparent film-like support does not contain a metal compound in its basic constituent components, it may be used to impart flexibility or stability during processing. , various metal-containing additives may be used as catalysts during polymerization. These metal-containing additives are auxiliary agents when processing the film-like support, and after forming the film-like support, they are usually dispersed in the resin layer rather than forming a cross-linked structure with the resin. It's just that.

However, when such a film-like support made of a resin to which a metal-containing additive is added is used for a radiation-curable adhesive tape, the metal ions of the metal-containing additive in the resin layer diffuse through the resin. Not only do metal ions move through the adhesive over time and cause deterioration of the radiation-curable adhesive layer, but also when this radiation-curable adhesive tape is bonded to a semiconductor wafer, the metal ions may cause damage to the adherend (semiconductor). A problem occurred in that it adhered to the wafer side and diffused, causing abnormalities in the electrical characteristics of the device. Further, such deterioration of the radiation-curable adhesive due to metal ions has an adverse effect on the decrease in the adhesive force for fixing the element after radiation irradiation, and may cause pick-up failure of the element.

[0008] Therefore, an object of the present invention is to stably reduce the adhesive force for fixing an element after radiation irradiation, even if a film-like support made of various resins is used as a support for a radiation-curable adhesive tape, and to prevent the element from being picked up. An object of the present invention is to provide a radiation-curable adhesive tape free from defects. A further object of the present invention is to provide a radiation-curable adhesive tape that does not adversely affect the electrical characteristics of small element pieces after dicing a semiconductor wafer even when a film-like support made of various resins is used for the radiation-curable adhesive tape. It's about doing.

[0009]

[Means for Solving the Problems] As a result of various studies to overcome the drawbacks of conventional radiation-curable adhesive tapes, the present inventors have developed a resin constituting a radiation-transparent film-like support. By adding a predetermined amount of a metal ion sequestering agent to the layer, it is possible to suppress the diffusion and movement of metal ions generated from the metal-containing additives dispersed in the resin layer, and it is possible to suppress the diffusion and movement of metal ions generated from the metal-containing additives dispersed in the resin layer, thereby providing a film-like support for radiation-curable adhesive tapes. We discovered that even when a resin containing such a metal-containing additive is used as a body, it hardens by radiation irradiation to produce a three-dimensional network structure, and at the same time exhibits a stable decrease in the adhesive force for fixing the element. Based on this knowledge, we have completed the present invention.

That is, the present invention provides a radiation-curable adhesive tape having a radiation-curable adhesive layer provided on one side of a radiation-transparent film-like support, in which a metal is included in the resin layer constituting the film-like support. Ion sequestering agent 0.01-1
The object of the present invention is to provide a radiation-curable adhesive tape characterized in that it contains 0% by weight. Note that radiation here refers to light rays such as ultraviolet rays, or ionizing radiation such as electron beams.

[0011] In the present invention, it is an essential requirement that a metal ion sequestering agent be contained in the resin layer constituting the radiation-transparent film-like support. Sequestering agents react with metal ions. As the sequestering agent of the present invention, a nitrogen-containing heterocyclic thiol compound represented by the formula Z-(SH)n (Z represents a nitrogen-containing heterocyclic group, and n represents an integer of 1 to 6) is preferable. . The heterocyclic group represented by Z in the above formula is 3-
Examples include 7-membered nitrogen-containing heterocyclic groups such as triazine, pyrimidine, pyridine, imidazole, triazole, tetrazole, thiazole, oxazole, selenazole, and benzimidazole. Among these, triazine, pyrimidine, and tetrazole are preferred.

Since the metal ion sequestering agent prevents the generation of metal ions in the film-like support, the polymerization initiator and radiation-curable compound contained in the adhesive of the radiation-curable adhesive tape can be used for a long time without deteriorating. Even after the device is held fixed for a period of time or stored on tape, the adhesive layer undergoes a polymerization reaction due to radiation irradiation so that the adhesive force for fixing the device is sufficiently reduced. In addition, by preventing the generation of metal ions in the film-like support using a metal ion sequestering agent, it is possible to eliminate metal ion migration to the adherend (semiconductor wafer), and it can be used as an adhesive tape for protecting element pieces or patterns after dicing. It also exhibits the effect of not causing defects in electrical characteristics of the device during use. This nitrogen-containing heterocyclic thiol compound has a thiol group, but this group is bonded to a nitrogen-containing heterocycle with high electronegativity, so it is much more stable than general thiol compounds, and the thiol group There is no effect such as deterioration of electrical characteristics on the element pieces due to dissociation.

[0013] The resins used in the film-like support used in the present invention include those mentioned above. Further, the film-like support is composed of a single resin layer or a plurality of resin layers. In the case of a plurality of resin layers, the sequestering agent may be contained only in the resin layer adjacent to the adhesive layer, but it can also be contained in all the resin layers.

The thickness of such a film support is usually 30 to 300 μm from the viewpoint of strength and elongation characteristics and radiation transparency.
m is appropriate. The radiation-curable adhesive provided on the film support is not particularly limited, but for example, 100 parts by weight of an acrylic adhesive, 5 to 500 parts by weight of a compound having a carbon-carbon double bond, and a photo-initiated adhesive. Examples include compositions containing additives, polymerization accelerators, and other known tackifiers, softeners, antioxidants, pigments, and the like.

Examples of the acrylic pressure-sensitive adhesive used in the present invention include a homopolymer having an ester of acrylic acid or methacrylic acid as a main constituent unit, acrylic acid or methacrylic acid, an ester thereof, or an acid amide thereof. and copolymers with other copolymerizable comonomers, or mixtures of these polymers. Monomers and comonomers thereof include, for example, alkyl esters of acrylic acid or methacrylic acid, such as methyl ester, ethyl ester, butyl ester, 2-ethylhexyl ester, octyl ester, glycidyl ester, hydroxymethyl ester, 2-hydroxyethyl ester, hydroxypropyl ester. , and amides and N-substituted amides of acrylic acid or methacrylic acid, such as N-hydroxymethylacrylic acid amide or methacrylic acid amide. If necessary, a crosslinking agent such as a polyisocyanate compound or an alkyl etherified melamine compound may be added thereto.

The compound having a carbon-carbon double bond used in the radiation-curable adhesive of the present invention is a radiation-polymerizable monomer, oligomer, or polymer, such as acrylate, methacrylate, cyanurate, isocyanurate, etc. It is. Specific examples include acrylates such as acrylate oligomers such as dipentaerythritol hexaacrylate and urethane acrylate oligomers, methacrylate, and cyanurate or isocyanurate compounds such as tris-2-acryloxyethyl isocyanurate, alone or in mixtures thereof. It may be. Furthermore, radiation-curable silicon acrylate or silicon methacrylate may be added to the adhesive in order to satisfactorily reduce the adhesive force for fixing the element after radiation irradiation.

In the present invention, it is particularly preferable to use a cyanurate compound or an isocyanurate compound as the compound having a carbon-carbon double bond. This is because the rate of decrease in adhesive strength after radiation irradiation is particularly large, and an excellent radiation-curable adhesive can be obtained. This cyanurate or isocyanurate compound is a compound having a triazine ring or isotriazine ring in the molecule and at least two radiation-polymerizable carbon-carbon double bonds, and is a monomer oligomer or a mixture thereof. There is no problem. Compounds having a triazine ring or isotriazine ring can generally be synthesized by a conventional cyclization reaction using a halocyan compound, dianiline compound, diisocyanate compound, etc. as raw materials. Furthermore, the compound synthesized in this way has radiation-polymerizable carbon-
Compounds used in the present invention can be obtained by introducing functional groups containing carbon double bond-containing groups, such as vinyl, acryloxy or methacryloxy groups.

In the present invention, the cyanurate or isocyanurate compound is not particularly limited except for the above points, but the carbon-carbon double bond-containing group introduced into the triazine ring or isotriazine ring has a so-called rigid molecular structure.
For example, those containing no aromatic heterocyclic groups are desirable. The reason for this is that if excessive rigidity is imparted to the radiation-polymerizable compound, the adhesive of the present invention becomes excessively brittle due to radiation curing. Therefore, it is preferable that the bonding group between the carbon-carbon double bond and the triazine ring or isotriazine ring contains a group that has a high degree of free rotation of atoms. Examples of these groups include aliphatic groups such as alkylene groups and alkylidene groups, which include -O-, -OC
It may have O-, -COO-, -NHCO-, -NHCOO- bonds, etc. In addition, when this bonding group is bonded to the triazine ring via -O-, at least one of the three alkylene groups, alkylidene groups, etc. bonded to this -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, tris(methacryloxyethyl)isocyanurate, bis(2-acryloxyethyl) 2- (5-acryloxy)hexyloxyethyl 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 at least 2, more preferably 2. ~6 pieces is good. If the number of double bonds is less than 2, a sufficient degree of crosslinking will not be obtained to reduce the adhesive strength by radiation irradiation, and if it exceeds 6, the adhesive will become too brittle after being cured by radiation. Sometimes.

The amount of the cyanurate compound or isocyanurate compound in the radiation-curable adhesive of the present invention is usually 5 to 50 parts by weight per 100 parts by weight of the acrylic adhesive.
It is 0 parts by weight. If this amount is too small, the three-dimensional reticulation of the radiation-curable adhesive by radiation irradiation will be insufficient, and the flowability of the acrylic adhesive cannot be controlled, making it easy to pick up the device. This is not preferable because the adhesive force for fixing the element does not decrease to a certain degree. On the other hand, if this amount is too large, the plasticizing effect on the acrylic adhesive will be large, and it will not be possible to obtain sufficient element fixing adhesive strength to withstand the cutting impact force caused by the rotating round blade during dicing or the water pressure of washing water. It disappears.

When the radiation-curable 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, diethylthioxanthone, benzyldimethylketanol, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenylpropane, etc. can be used in combination. . By adding one or more of these to the pressure-sensitive adhesive layer, the curing reaction can proceed efficiently with at least the curing reaction time or the amount of ultraviolet irradiation, and the adhesive force for fixing the element can be reduced. The thickness of the radiation-curable adhesive layer provided on this sheet or film-like support is not particularly limited, but is usually suitably 2 to 50 μm.

[0023]

EXAMPLES The present invention will be explained in detail below based on examples.

Example 1 100 parts by weight of an acrylic adhesive (a copolymer of 2-ethylhexyl acrylate and n-butyl acrylate), 3 parts by weight of a polyisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name Coronate L), and isocyanurate. 60 parts by weight of tris-2-acryloxyethyl isocyanurate was added as a compound, and α-
A radiation-curable adhesive was prepared by adding and mixing 1 part by weight of hydroxycyclohexyl phenyl ketone. This adhesive was corona-treated on the surface of a 70 μm thick film-like support made by adding 2% of 2-dibutylamino-4,6-dimercapto-s-triazine as a triazinethiol compound to a high-density polyethylene resin. A radiation-curable pressure-sensitive adhesive tape was obtained by coating this surface to a thickness of 20 μm after drying.

A silicon wafer with a diameter of 5 inches was attached to the radiation-curable adhesive tape and left in a constant temperature and humidity chamber set at a temperature of 60° C. and a humidity of 65% for 168 hours (one week). - Adhesive strength before and after UV irradiation was measured based on Z0237. (90° peeling, peeling speed 5
0 mm/min, and the following examples and comparative examples are based on this method. ). Here, the ultraviolet lamp is a high pressure mercury lamp 80w/
cm, the irradiation time is 10 seconds, and the cumulative light amount is 1000.
mJ/cm2. The results are shown in Table 1.

Furthermore, a silicon wafer having a diameter of 5 inches and having an oxide film (SiO2) formed on its surface was attached to the radiation-curable adhesive tape at a temperature of 60°C and a humidity of 65%.
The tape was left in a constant temperature and humidity bath for 168 hours (one week), and then irradiated with ultraviolet rays to peel off the tape from the silicon wafer. An Al electrode was formed on the surface of this silicon wafer to produce a diode with a MOS structure. For this MOS diode, the amount of mobile charge per unit area (Q0/q) in the diode characteristics is calculated from the IV characteristic curve, and calculated from the MOS diode manufactured from a wafer to which no radiation-curable adhesive tape is attached. When compared with the amount of mobile charge per unit area, almost no difference was observed.

[0027] Here, the measurement of the amount of mobile charge (Q0) is as follows:
Based on the IV characteristic curve obtained by the TVS method, Q0 is determined from the triangular area of the peak portion of the displacement current. The measurement conditions at this time were to hold the sample semiconductor wafer at 250°C.
The probe was fixed on a stage heated to
The displacement current is measured by varying the applied voltage up to (the following examples and comparative examples are based on this method). Next, in order to investigate the metal content contained in the film-like support of this radiation-curable adhesive tape, qualitative analysis was performed using emission spectroscopy. These results are shown in Table 2.

Example 2 As a film-like support for a radiation-curable adhesive tape, 2-dibutylamino-4,6-dimercapto- was used as a triazinethiol compound in a linear low-density polyethylene resin.
A film-like support with a thickness of 100 μm was prepared by adding 5% of s-triazine. The same radiation-curable adhesive was coated onto this film-like support in the same manner as in Example 1 so that the thickness after drying was 20 μm to obtain a radiation-curable adhesive tape.

Comparative Example 1 A radiation-curable adhesive tape was prepared in the same manner as in Example 1 except that the triazinethiol compound was not added to the high-density polyethylene resin of the film-like support.

Comparative Example 2 A radiation-curable adhesive tape was prepared in the same manner as in Example 2, except that no triazinethiol compound was added to the linear low-density polyethylene resin of the film support.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

Effects of the Invention As is clear from the above test results, in the radiation-curable adhesive tape of the present invention, an ion sequestering agent is added to the resin layer constituting the radiation-transparent film-like support. Even if a resin containing 20% is used as a film-like support, it will prevent the generation of metal ions in the film-like support, and prevent the polymerization initiator contained in the adhesive of radiation-curable adhesive tape and radiation-curable Even if the device is fixed and left for a long time without deterioration of the compound, or even if adhesive tape is used after long-term storage, the device fixing adhesive strength is sufficiently reduced by radiation irradiation, and there is no adhesive residue. This has an excellent effect in that small element pieces can be picked up well from the radiation-curable adhesive tape. Furthermore, even when this radiation-curable adhesive tape is used as a tape for protecting the patterned surface of semiconductor wafers, there is no transfer of metal ions to the semiconductor wafer, which is the adherend, and it has the advantage of not causing defects in electrical characteristics of devices. It also has other effects.

Claims (2)

[Claims] Claim 1: A metal ion sequestering agent is contained in a resin layer configured as a radiation-transparent film-like support.
A radiation-curable adhesive tape containing 10% by weight. 2. The radiation-curable adhesive tape according to claim 1, wherein the sequestering agent is a nitrogen-containing heterocyclic thiol compound.