CN1703773B - Laminated body and method and apparatus for producing ultra-thin substrate using the laminated body - Google Patents

Abstract

A laminate is provided which comprises a substrate to be ground and a carrier, the substrate being ground to a small thickness and being separable from the carrier without damaging the substrate. An example of the present invention is a laminate comprising a substrate to be ground, a bonding layer in contact with the substrate to be ground, a photothermal conversion layer containing a light absorbent and a thermally decomposable resin, and a light-transmitting support. After the surface of the substrate opposite to the contact surface of the bonding layer is ground, the laminated body is irradiated through the light-transmitting layer, and the photothermal conversion layer is decomposed to separate the substrate from the light-transmitting support.

Description

Laminated body and method and apparatus for producing ultra-thin substrate using the laminated body

technical field

The present invention relates to a laminate in which a substrate to be ground, such as a silicon wafer, fixed on a carrier can be easily separated from the carrier, the invention also relates to a method and apparatus for manufacturing the laminate, As well as methods and apparatus for fabricating thinned substrates.

Background technique

Reduction of substrate thickness is generally required in various fields. For example, in the field of quartz devices, it is required to reduce the thickness of the quartz wafer to increase the oscillation frequency. Particularly in the semiconductor industry, efforts are being made to further reduce the thickness of semiconductor wafers for the purpose of reducing the thickness of semiconductor packages and high-density assembly by chip lamination technology. On the surface opposite to the surface containing the patterned circuits, the semiconductor wafer is subjected to so-called back grinding to reduce the thickness. In the common technique of grinding the back side or surface of a wafer and transferring the wafer, when the wafer is fixed with only one back grinding protective tape, the thickness of the wafer is reduced due to problems such as uneven thickness of the ground wafer or warping of the wafer with the protective tape after grinding. In practice it can only be reduced to about 150 microns (μm). For example, Japanese Unexamined Patent Publication (Kokai) 6-302569 discloses a method in which a wafer is fixed on a ring-shaped frame with a pressure-sensitive adhesive tape, the back side of the wafer fixed on the frame is ground, and the The wafer is transferred to the next process. However, this method cannot significantly increase the existing wafer thickness level, and at the same time cannot avoid the occurrence of the above-mentioned non-uniformity or warpage problems.

A method of firmly fixing a wafer on a hard carrier by an adhesive while grinding the backside of the wafer and transferring the wafer has also been proposed. Its purpose is to prevent breakage of the wafer during backgrinding and transfer by supporting the wafer with the carrier. According to this method, wafers can be processed to a smaller thickness than the above method, however, ultra-thin wafers cannot be separated from the carrier without damaging the wafers, so this method cannot be practically used as a method for thinning semiconductor wafers. method.

Invention content

Accordingly, it is an object of the present invention to provide a laminate in which a substrate to be ground is fixed on a carrier from which the substrate to be ground can be easily peeled off. Objects of the present invention include providing a method for manufacturing the laminate, and a method and apparatus for manufacturing ultra-thin substrates using the laminate.

In one example of the present invention, a laminate is provided, which includes a substrate to be ground; an adhesive layer in contact with the substrate to be ground; a conversion layer; and a light-transmitting carrier. After grinding the surface of the substrate opposite to the contact surface of the adhesive layer, the laminate is irradiated through the light-transmitting layer to decompose the light-to-heat conversion layer and separate the substrate from the light-transmitting carrier. In this laminate, the substrate ground to a small thickness can be separated from the carrier without damaging the substrate.

In another example of the present invention, a method for manufacturing the above-mentioned laminate is provided, the method comprising: coating a light-transmitting carrier with a solution containing a light absorbing agent and a thermally decomposable resin or as a thermally decomposable resin precursor material The light-to-heat conversion layer precursor of the monomer or oligomer; dry and solidify or cure the light-to-heat conversion layer precursor on the light-transmitting carrier to form the light-to-heat conversion layer; apply on the substrate to be ground or the light-to-heat conversion layer The adhesive is used to form an adhesive layer; the substrate to be polished and the light-to-heat conversion layer are bonded through the adhesive layer under reduced pressure to form a laminated body.

Under reduced pressure, the substrate to be ground and the light-transmitting carrier are bonded through the adhesive layer to prevent the formation of air bubbles and dust contaminants in the laminate, so that a horizontal surface can be formed after grinding and the uniformity of the thickness of the substrate can be maintained.

In another example of the present invention, an apparatus for manufacturing the above-mentioned laminate is provided, in which the light-to-heat conversion layer formed on the light-transmitting carrier is laminated on the surface to be ground through an adhesive layer under reduced pressure. On the substrate, the apparatus includes (1) a vacuum chamber that can be decompressed to a predetermined pressure, (2) a support located in the vacuum chamber on which (i) the substrate to be ground or (ii) the light-transmissive A carrier on which a light-to-heat conversion layer is formed, and (3) a fixing/releasing device located in the vacuum chamber which can move in the vertical direction on the upper part of the support, capable of holding another substrate to be ground or formed on it. The outer edge of the light-transmitting carrier with the light-to-heat conversion layer can also be loosened when the substrate to be ground is very close to the light-to-heat conversion layer.

When using this equipment, since the laminate is manufactured under reduced pressure, it prevents the formation of air bubbles and dust contamination in the laminate, and the fixing/releasing device does not damage the surface to be laminated.

In another example of the present invention, a method for manufacturing a substrate with reduced thickness is provided, the method comprising: preparing the above-mentioned laminate, grinding the substrate to a required thickness, and irradiating the light-to-heat conversion layer through a light-transmitting carrier to make The light-to-heat conversion layer is decomposed to separate the substrate from the light-transmitting carrier after grinding, and the adhesive layer is peeled off from the substrate after grinding. In this method, the substrate may be ground to a desired thickness (e.g., 150 microns or less, preferably 50 microns or less, more preferably 25 microns or less) on a carrier, and after grinding, exposed to The carrier is separated from the substrate by the radiation energy, so that the adhesive layer remaining on the substrate can be easily peeled off from the substrate after grinding.

In another embodiment, the present invention provides an apparatus for manufacturing ground substrates, the apparatus comprising a grinder adapted to grind the laminate substrates described above, the radiant energy source will be described in more detail below, which can pass through the the photocarrier provides enough high radiant energy to the light-to-heat conversion layer to decompose the light-to-heat conversion layer, thereby separating the substrate and the light-transmitting carrier after grinding; and a separator adapted to remove from the The adhesive layer was removed from the substrate.

Description of drawings

Figure 1 is a cross-sectional view of several examples of the present invention.

Fig. 2 is a cross-sectional view of vacuum bonding equipment suitable for use in the present invention.

Figure 3 is a partial sectional view of grinding equipment suitable for use in the method of the present invention.

Figure 4 shows the process of separating the carrier and peeling off the adhesive layer.

Fig. 5 is a cross-sectional view of a laminate fixing device usable in the laser beam irradiation process.

Fig. 6 is a perspective view of a laser irradiation device.

Fig. 7 is a schematic diagram of a picker for separating a wafer from a carrier.

Figure 8 shows a schematic diagram of how to peel off the adhesive layer from the wafer.

Fig. 9 is a schematic diagram of an apparatus for measuring the adhesive strength of an adhesive layer.

Detailed ways

An important structural feature of the laminated body of the present invention is that a light-to-heat conversion layer is arranged between the substrate to be polished and the light-transmitting carrier. When irradiated with radiant energy such as a laser beam, the light-to-heat conversion layer decomposes, allowing the substrate to be separated from the carrier without causing any damage. Therefore, the substrate thickness provided by the present invention cannot be obtained by conventional methods.

Fig. 1 shows some examples of laminates of the present invention. In the laminated body 1 of FIG. 1( a ), the substrate to be polished 2 , the adhesive layer 3 , the light-to-heat conversion layer 4 and the carrier 5 are sequentially laminated. Also, as shown in accompanying drawing 1(b), the adhesive layer 3 may be a double-sided adhesive tape 8 comprising a first intermediate layer (film) 6 having a pressure sensitive adhesive on both surfaces thereof 7. Also, as shown in FIGS. 1( c ) and ( d ), the adhesive layer 3 may be a double-sided adhesive tape 8 which is integrated with the light-to-heat conversion layer 4 . In addition, as shown in FIG. 1(e), the adhesive layer 3 may be a double-sided adhesive tape 8 in which the light-to-heat conversion layer 4 itself includes a light-to-heat conversion layer 4' having pressure-sensitive adhesiveness. As shown in Figure 1(f), it is also possible to arrange a first intermediate layer 6 between the adhesive layer 3 and the light-to-heat conversion layer 4, and to arrange a second intermediate layer 9 between the light-to-heat conversion layer 4 and the carrier 5. , the second intermediate layer 9 and the carrier 5 are bonded by another adhesive layer 3'.

The components constituting the laminated body of the present invention will be described in more detail below.

Substrate

The substrate can be, for example, a brittle material that is difficult to thin by conventional methods. Examples include semiconductor wafers such as silicon and gallium arsenide, quartz wafers, sapphire and glass.

Light-transmitting carrier

The light-transmitting carrier is a material that can transmit radiation energy, such as the laser beam used in the present invention. It is required that the material can keep the grinding body in a flat state and will not break the grinding body during grinding and transmission. There is no limit to the light transmittance of the carrier, as long as it does not affect the transmission of radiant energy at a practical intensity level into the light-to-heat conversion layer and decomposes the light-to-heat conversion layer. However, it is preferable that its transmittance is 50% or higher. Moreover, in order to prevent the grinding body from warping during the grinding process, it is preferred that the light-transmitting carrier has a sufficiently high rigidity, preferably the flexural stiffness of the carrier is 2×10 ^-3 (Pa·cubic meter) or greater, more preferably It is 3×10 ^-2 (Pa·cubic meter) or larger. Examples of useful supports include glass and acrylic sheets. Furthermore, in order to enhance the adhesive strength with the adjacent layer such as the light-to-heat conversion layer, the support may be surface-treated with a silane coupling agent or the like when necessary. When using a UV-curable light-to-heat conversion layer or an adhesive layer, it is preferred that the carrier is transparent to UV radiation.

Sometimes when the light-to-heat conversion layer is irradiated, or when a high temperature is generated due to heat generated by friction during grinding, the carrier is subjected to the heat generated by the light-to-heat conversion layer. Furthermore, in order to form a metal thin film on a substrate, vapor deposition, plating or etching may be applied before separating the ground substrate from the carrier. Particularly in the case of a silicon wafer, sometimes the support is subjected to high temperature treatment to form an oxide film. Therefore, choose a support that has heat resistance, chemical resistance, and a low coefficient of expansion. Examples of support materials with these properties include borosilicate glasses of Pyrex ^™ and Tenpax ^™ , and alkaline earth boroaluminosilicate glasses such as Corning ^™ #1737 and #7059.

In order to obtain the required thickness uniformity after grinding the substrate, it is preferred that the thickness of the support is uniform. For example, in order to grind silicon wafers to 50 microns or less with a uniformity of ±10% or less, the variability in carrier thickness must be reduced to ±2 microns or less. When the carrier is used repeatedly, it is also preferred that the carrier has scratch resistance. In order to reuse the carrier, it is necessary to select a suitable radiant energy wavelength and carrier to suppress the damage of the radiant energy to the carrier. For example, when using Pyrex glass as the carrier and using the third harmonic generation YAG laser (355 nm), the separation of the carrier and the substrate can be carried out, but the carrier exhibits low transmittance at this laser wavelength and can absorb this radiation Yes, as a result, the carrier is thermally damaged and can no longer be used in certain situations.

Light-to-heat conversion layer

The light-to-heat conversion layer contains a light absorbing agent and a thermally decomposable resin. Radiant energy applied to the light-to-heat conversion layer in the form of a laser beam or the like is absorbed by the light absorber, and converted into thermal energy. The generated heat energy causes the temperature of the light-to-heat conversion layer to rise sharply, reaching the thermal decomposition temperature of the thermally decomposable resin (organic component) in the light-to-heat conversion layer, causing the resin to undergo thermal decomposition. It is believed that the gas generated by thermal decomposition forms a void layer (such as an air gap) in the light-to-heat conversion layer and divides the light-to-heat conversion layer into two parts, thereby separating the carrier and the substrate.

Light absorbers are capable of absorbing radiant energy at the wavelength used. The radiant energy is usually a laser beam with a wavelength of 300 to 11000 nm, preferably 300 to 2000 nm, specific examples of which include YAG laser, which emits a laser with a wavelength of 1064 nm; second harmonic generation YAG laser, whose wavelength is 532 nm ; and a semiconductor laser having a wavelength of 780 to 1300 nanometers. Although light absorbers vary depending on the wavelength of the laser beam, examples of suitable light absorbers include carbon black, graphite powder, particulate metal powders such as iron, aluminum, copper, nickel, cobalt, manganese, chromium, zinc and tellurium, metal oxides Powders, such as black titanium oxide, and dyes and pigments, such as aromatic diamino metal complexes, aliphatic diamine metal complexes, aromatic dithiol metal complexes, mercaptophenol-based metal complexes, squarylium-based Compounds, cyanine-based dyes, methine-based dyes, naphthoquinone-based dyes and anthraquinone-based dyes. The light absorber may be in the form of a thin film, including a vapor deposited metal film. Among these light absorbers, carbon black is particularly useful because it significantly reduces the force required to detach the substrate from the support after irradiation and accelerates the detachment process.

The concentration of light absorbing agent in the light-to-heat conversion layer varies depending on the kind of light absorbing agent, particle state (structure) and degree of dispersion, but the concentration of ordinary carbon black having a particle size of about 5 to 500 nm is usually 5 to 70% by volume. If its concentration is less than 5% by volume, the heat generated by the light-to-heat conversion layer may not be enough to decompose the thermally decomposable resin, and if it is more than 70% by volume, the film-forming performance of the light-to-heat conversion layer will deteriorate and may be easily Loss of adhesion to other layers. When a UV-curable adhesive is used as the adhesive for the adhesive layer, if the carbon black content is too high, the UV transmittance for curing the adhesive will decrease. Therefore, when using an ultraviolet curable adhesive as an adhesive layer, the carbon black content should be 60% by volume or less. In order to reduce the force required to remove the carrier after irradiation, thereby preventing the light-to-heat conversion layer from being abraded during grinding (such as the abrasion caused by the abrasive in the washing water), the carbon black content in the light-to-heat conversion layer is preferably 20 to 60% by volume , more preferably 35 to 55% by volume.

Examples of useful thermally decomposable resins include gelatin, cellulose, cellulose esters (e.g., cellulose acetate, nitrocellulose), polyphenols, polyvinyl butyral, polyvinyl acetal, polycarbonate Esters, polyurethanes, polyesters, polyorthoesters, polyacetals, polyvinyl alcohols, polyvinylpyrrolidones, copolymers of vinylidene chloride and acrylonitrile, poly(meth)acrylates, polyvinyl chloride, silicones Resins and block copolymers containing polyurethane units. These resins may be used alone or in combination of two or more. The glass transition temperature (Tg) of the resin is preferably room temperature (20° C.) or higher, so as to prevent the light-to-heat conversion layer from being bonded again once it is separated due to thermal decomposition of the thermally decomposable resin to form a void layer, and more It is preferable that Tg is 100°C or higher in order to prevent rebonding from occurring. When the light-transmitting carrier is glass, in order to increase the adhesion between the glass and the light-to-heat conversion layer, a polar group that can hydrogen bond with the silanol group on the glass surface can be used (eg -COOH, -OH) thermally decomposable resins. Moreover, in applications that require chemical solution treatment such as chemical etching, in order to make the light-to-heat conversion layer chemically resistant, a thermally decomposable resin with a functional group capable of self-crosslinking during heat treatment can be used in the molecule, which can be UV or Visible light crosslinkable thermally decomposable resins or precursors thereof (eg, mixtures of monomers and/or oligomers). In order to form the heat conversion layer as a pressure-sensitive adhesive light-to-heat conversion layer as shown in Fig. 1(e), a pressure-sensitive adhesive polymer formed from poly(meth)acrylate or the like was used as Thermally decomposed resin.

transparent filler

If necessary, the light-to-heat conversion layer may contain a transparent filler. The transparent filler serves to prevent the light-to-heat conversion layer from being bonded again once it is separated due to thermal decomposition of the thermally decomposable resin to form a void layer. Thus, the force required to separate the substrate and carrier after grinding the substrate and subsequent irradiation can be further reduced. Also, since re-adhesion can be prevented, the range of selection of thermally decomposable resins is widened. Examples of transparent fillers include silica, talc and barium sulfate. The use of transparent fillers is particularly advantageous when using UV-curable adhesives as adhesive layers. Currently believed to be due to the following reasons. When particulate light absorbers such as carbon black are used, this light absorber acts to reduce the force required for separation and also acts to interrupt the transmission of UV light. Therefore, when a UV-curable adhesive is used as an adhesive layer, the curing process may not proceed satisfactorily, or may take a very long time. In this case, when transparent fillers are used, the substrate and carrier can be easily separated after irradiation without affecting the curing process of the UV-curable adhesive. When using particulate light absorbing agents such as carbon black, the content of transparent filler can be determined according to the total amount of light absorbing agent. The total amount of particulate light absorbing agent (such as carbon black) and transparent filler in the light-to-heat conversion layer is preferably 5 to 70% by volume of the light-to-heat conversion layer. When the total amount is within this range, the force required to separate the substrate and the carrier can be significantly reduced. However, the force required for separation is also affected by the shape of the particulate light absorber and transparent packing. More specifically, the use of small amounts of filler can sometimes be more effective in reducing the force required for separation when the particle shape is more complex (due to the state of the particle due to the more complex structure) than when the particle shape is simpler, such as near spherical .

Therefore, in some cases, the total amount of particulate light absorber and transparent filler is determined as a "top filler volume concentration" (TFVC). This refers to the filler volume concentration when the mixture of the particulate absorbent and the transparent filler is in a dry state and the thermally decomposable resin is mixed with the filler at a content that only fills the void volume. That is, the TFVC when the thermally decomposed resin is mixed with the filler at a content that only fills the void volume in the mixture of the particulate light absorber and the transparent filler is the highest filler volume concentration of 100%. The total amount of particulate light absorbing agent and transparent filler in the light-to-heat conversion layer is preferably 80% or more of the highest filler volume concentration, more preferably 90% or more. In further clarification, the total volume percent of filler (eg, carbon black and transparent filler) is expressed as "A", and the highest filler volume percent, TFVC (total volume percent of filler and resin filling the void volume of the filler) is expressed as "B", then A/B is preferably greater than about 80% (more preferably A/B > 90%).

The oil absorption can be used to express the void volume of the filler by the amount of liquid required to fill the void volume of the unit weight of the filler. For carbon black, use the measured value from the commercial catalogue, and for transparent fillers (eg, silica) use the typical value for this type of silica (200 g/cm3).

While not being bound by any theory, it is currently believed that the light absorbing agent (such as carbon black) in the light-to-heat conversion layer absorbs laser energy irradiated through the transparent carrier and converts it into thermal energy, decomposing the matrix resin and generating gas or voids. As a result, the void separates the layer into two parts, eg forming two layers, and then allows the semiconductor wafer to be peeled off from the carrier. Surfaces separated by voids only come into contact with surfaces again after a while. The surface has carbon black particles and residual resin whose molecular weight has been reduced due to thermal decomposition. During recontact (eg, rebonding), this residual resin increases adhesion. On the other hand, when both the light-to-heat conversion layer and the adhesive layer are soft, the recontact area will be relatively large, making the adhesion greater and it is difficult to peel the ultra-thin wafer from the carrier without damage or cracking . In the present invention, setting A/B>80%, preferably A/B>90%, can reduce the residual resin on the peeled surface. Thereby, adhesion due to re-contact can be minimized. Moreover, while increasing the amount of carbon black, use transparent fillers to meet the requirements of A/B > 80%, or > 90%, at least to maintain the required thickness of the light-to-heat conversion layer, while maintaining Type required UV transparency.

Therefore, when the total amount is within this range, the carrier can be easily separated after irradiation.

The thickness of the light-to-heat conversion layer is usually about 0.5 microns. If the thickness is too small, the adjacent adhesive layer is partially exposed to the peeling surface, which will improve the adhesion of the peeling surface, especially when the adhesive layer is relatively soft, which will make it difficult to peel off the ultra-thin wafer (unless in case of rupture).

The light-to-heat conversion layer may contain other additives, if necessary. For example, in the case where the layer is formed by coating a thermally decomposable resin in monomer or oligomer form, and then polymerizing or curing the resin, the layer may contain a photopolymerization initiator. Moreover, adding a coupling agent (integral blending approach, i.e., using a coupling agent as an additive in the formulation, rather than as a pre-surface treatment agent) increases the adhesion between the glass and the light-to-heat conversion layer, as well as adding cross-linking Agents improve chemical resistance and can effectively achieve their respective purposes. Furthermore, in order to promote separation due to decomposition of the light-to-heat conversion layer, a low-temperature gas generating agent may be contained. Representative examples of usable low temperature gas generating agents include blowing agents and sublimating agents. Examples of blowing agents include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, zinc carbonate, azodicarbonamide, azobisisobutyronitrile, N,N'-dinitrosopentamethylenetetramine, para -tosylhydrazide and p,p-oxybis(benzenesulfonylhydrazide). Examples of sublimating agents include 2-diazo-5,5-dimethylcyclohexane-1,3-dione, camphor, naphthalene, borneol, butyramide, valeramide, 4-tert-butylphenol, Furan-2-carboxylic acid, succinic anhydride, 1-adamantanol and 2-adamantanone.

The photothermal conversion layer can be formed by mixing a light absorbing agent such as carbon black, a thermally decomposable resin, and a solvent to prepare a precursor coating solution, coating the solution on a carrier, and drying it. Also, a light absorbing agent, a monomer or an oligomer as a precursor material of a thermally decomposable resin, and optional additives such as a photopolymerization initiator, and if necessary, a solvent are mixed to prepare a precursor coating solution, Instead of a thermally decomposable resin solution, the solution is coated on a support, dried and polymerized/cured, and the light-to-heat conversion layer can be formed. For coating, general-purpose coating methods suitable for coating on hard supports, such as spin coating, die coating, and roll coating, can be used. When forming the light-to-heat conversion layer in the double-sided adhesive tape shown in Figure 1 (c) to (e), methods such as die coating, gravure coating, and knife coating can be used to form the light-to-heat conversion layer on the film.

In general, the thickness of the light-to-heat conversion layer is not limited as long as the carrier and the substrate can be separated, but the thickness is usually 0.1 micron or more. If the thickness is less than 0.1 µm, the concentration of the light absorbing agent required for sufficient light absorption becomes high, which makes the film-forming properties inferior and, as a result, adhesion to adjacent layers becomes impossible. On the other hand, if the thickness of the light-to-heat conversion layer is 5 micrometers or more, and the light-absorbent concentration required to thermally decompose and separate the light-to-heat conversion layer is kept constant, the transmittance of the light-to-heat conversion layer (or its precursor) The light rate will be reduced. As a result, when using a light-to-heat conversion layer and an adhesive layer that are photocurable such as ultraviolet curable light, the curing process is sometimes inhibited to the extent that a sufficiently cured product cannot be obtained. Therefore, when the light-to-heat conversion layer is, for example, UV-curable, in order to minimize the force required to separate the substrate from the carrier after irradiation, and to prevent the light-to-heat conversion layer from being worn out during grinding, it is preferable that the light-to-heat conversion layer The thickness is about 0.3 to 3 microns, more preferably about 0.5 to 2.0 microns.

Adhesive layer

The substrate to be polished is fixed on the carrier through the light-to-heat conversion layer with an adhesive layer. After separating the substrate and the carrier by decomposition of the light-to-heat conversion layer, a substrate having an adhesive layer thereon can be obtained. Therefore, the adhesive layer must be easily detachable from the substrate, for example by peeling. Thus, the adhesive layer has an adhesive strength high enough to hold the substrate on the carrier, but sufficiently low to allow separation from the substrate. Examples of adhesives that can be used as the adhesive layer of the present invention include rubber-based adhesives obtained by dissolving rubber, elastomer or the like in a solvent; epoxy-, urethane-based or the like One-component thermosetting adhesives; two-component thermosetting adhesives based on epoxy, urethane, acryl or similar; hot melt adhesives; acryl, epoxy or similar UV or electron beam curable adhesives; and aqueous dispersion type adhesives. Suitable UV-curable adhesives are obtained by adding a photopolymerization initiator and, if necessary, additives to (1) an oligomer having a polymerizable vinyl group such as urethane acrylate , epoxy acrylate or polyester acrylate, and/or (2) acrylic or methacrylic monomers. Examples of additives include thickeners, plasticizers, dispersants, fillers, flame retardants and heat stabilizers.

In particular, silicon wafers to be ground often have a certain roughness, such as a circuit pattern on one side. For an adhesive layer that fills the roughness on the substrate to be ground and makes the thickness of the adhesive layer uniform, it is preferred that the adhesive used for the adhesive layer is in a liquid state during coating and lamination, preferably during coating and layering. The viscosity is less than 10,000 centipoise (cps) at the operating temperature (eg, 25° C.). Among the various methods described below, it is preferable to apply such a liquid adhesive by spin coating. Ultraviolet-curable adhesives and visible-light-curable adhesives are particularly preferable as such adhesives because these adhesives can make the thickness of the adhesive layer uniform and can increase the processing speed for the above reasons.

For solvent-based adhesives, at the application conditions after removal of the adhesive solvent, for curable adhesives, at the application conditions after curing, or for hot-melt adhesives, at It is preferred that the adhesive has a storage modulus of 100 MPa or more at 25°C and a storage modulus of 10 MPa or more at 50°C under application conditions after normal temperature hardening. With this elastic modulus, the substrate to be ground can be prevented from warping or deformed due to stress during grinding, and can be uniformly ground into an ultra-thin substrate. The storage modulus or modulus of elasticity used here can be measured in tension at a frequency of 1 Hz, a strain of 0.04% and a heating rate of 5 °C/min using a sample of the adhesive 22.7 mm x 10 mm x 50 microns in size Take measurements. The storage modulus can be measured using SOLIDS ANALYZER RSA II (trade name) manufactured by Rheometrics, Inc.

Double-sided adhesive tapes shown in Figs. 1(b) to (e) can be used as the adhesive layer. In such double-sided adhesive tapes, there are generally pressure-sensitive adhesive layers on both surfaces of the backing material. Examples of suitable pressure-sensitive adhesives include adhesives mainly containing acryl, urethane, natural rubber or the like, and adhesives additionally containing a crosslinking agent. Among them, an adhesive containing 2-ethylhexyl acrylate or butyl acrylate as a main component is preferable. Use paper or plastic film or similar as backing material. The backing as used herein must be sufficiently flexible to allow release of the adhesive layer from the substrate by peeling.

It has also been found that specific photocurable adhesives are preferred when grinding substrates to ultra-thin thicknesses. When grinding substrates to a thickness of 50 microns or less, problems sometimes arise such as water ingress into the interface between the substrate and the adhesive layer, chipping of the substrate edges, or damage to the central portion of the substrate. To avoid these problems, grinding is generally performed at a slower rate. This extends the grinding time by twice the time required to grind to normal polish thicknesses of 150 microns or greater. For example, by reducing the number of rotations of the grinding wheel, damage can be avoided. In general, after grinding the backside, ultra-thin semiconductor wafers are subjected to a polishing process to remove residual damaged layers (layers damaged by grinding rather than single crystals). In the grinding or polishing process, in order to avoid the problem of water entering the interface between the substrate and the adhesive layer, chipping the edge of the substrate, or damaging the central part of the substrate without sacrificing the grinding speed, the adhesive layer The bond strength (split mode, see FIG. 9 and description below) of the substrate to be abraded is at least about 2.0 (N/3.5 cm2) or greater when measured as described in the Examples below.

When the photocurable adhesive is cured on the substrate to be polished, the bonding area is reduced due to curing shrinkage, and the bonding strength to the substrate is also liable to decrease. In order to ensure the above-mentioned adhesive strength, it is preferable that the photocurable adhesive is an adhesive that recovers adhesive strength when heated above its glass transition temperature (Tg). The adhesive has a minimum storage modulus of 3.0 x 10 ⁷ to 7.0 x 10 ⁷ Pa as measured at 25 to 180°C. If the minimum storage modulus is too high, a sufficiently high adhesive strength cannot be obtained, resulting in water entering into the interface between the substrate and the adhesive layer, chipping of the edge of the substrate or damage to the central portion of the substrate. On the other hand, if the minimum storage modulus is too low, it is difficult to separate the adhesive layer (adhesive layer) after a heating process, such as lamination to a sheet bonding tape.

Moreover, at the highest attainable temperature, the storage modulus of the interface between the substrate and the adhesive layer during grinding (usually 40 to 70°C, such as 50°C) is preferably 9.0×10 ⁷ Pa or higher, more preferably Preferably it is 3.0 x 10 ⁸ Pa or higher. When the storage modulus is within this range, it is possible to prevent the adhesive layer from being locally deformed to the extent that the substrate to be polished (silicon wafer) is damaged due to the pressing of the grinding tool in the vertical direction during grinding.

As an example of a photocurable adhesive satisfying all these conditions, the total amount of difunctional urethane (meth)acrylate oligomers having a molecular weight of 3000 or higher is 40% by weight or more, and the difunctional ( Adhesives having a total amount of meth)acryloyl monomers of 25% by weight or more are known and suitable. However, such an adhesive is not particularly limited as long as it has necessary properties (adhesive strength, functional properties).

The thickness of the adhesive layer is not particularly limited as long as it can ensure the thickness uniformity required for the grinding of the substrate to be ground and the tear strength required for peeling the adhesive layer from the wafer after the carrier is removed from the laminate, and can sufficiently It is enough to cover the roughness on the substrate surface as much as possible. The thickness of the adhesive layer is usually about 10 to 150 microns, preferably about 25 to 100 microns.

Other useful additives

Because the substrate to be ground of the laminate of the present invention may be a wafer on which circuits are formed, the wafer circuits may be damaged by radiant energy such as laser beams passing through the light-transmitting carrier, the light-to-heat conversion layer and the adhesive layer and reaching the wafer. . In order to prevent such circuit damage, any layer constituting the laminate or a layer provided independently between the light-to-heat conversion layer and the wafer may contain a light-absorbing dye or a reflective dye that absorbs light at the wavelength of radiant energy. Reflective light pigment for this light. Examples of light-absorbing dyes include dyes having absorption peaks near the wavelength of the laser beam used (eg, phthalocyanine-based dyes and cyanine-based dyes). Examples of light-reflecting pigments include inorganic white pigments such as titanium oxide.

Additional useful layers

Additional layers other than the substrate to be polished, the adhesive layer in contact with the substrate to be polished, the light-to-heat conversion layer and the light-transmitting carrier may be included in the laminate of the present invention. Examples of additional layers include a first intermediate layer 6 as shown in Figure 1 (f), which is located between the adhesive layer 3 and the light-to-heat conversion layer 4; and/or a second intermediate layer 9, which is located Between layer 4 and carrier 5. Preferably, the second intermediate layer 9 is bonded to the carrier 5 via an adhesive layer 3' (eg, a pressure-sensitive adhesive).

When the first intermediate layer 6 is present, the laminate 1 is separated at the light-to-heat conversion layer 4 after irradiation to obtain a laminate of the first intermediate layer 6 /adhesive layer 3 /substrate 2 . Therefore, the first intermediate layer 6 acts as a backing when separating the adhesive layer 3 from the substrate 2, enabling easy separation of the two. The first intermediate layer 6 is preferably a multilayer optical film. Furthermore, the first intermediate layer 6 is preferably a thin film capable of selectively reflecting radiant energy for separation such as YAG laser light (near-infrared wavelength light). Such films are preferred because while the first interlayer 6 is non-transmissive but reflective of radiant energy, it prevents radiant energy from reaching the surface of the wafer with circuitry, which eliminates the possibility of damaging the circuitry. When a photocurable adhesive is used as the adhesive layer 3, a film having a sufficiently high transmittance of curing light such as ultraviolet light is preferable. Therefore, it is preferred that the multilayer optical film transmits ultraviolet light and selectively reflects near infrared light. A preferred multilayer optical film that transmits ultraviolet light and reflects near infrared light may be 3M ^™ Solar reflective film (3M Company, St. Paul, MN). This first intermediate layer 6 acts as a base sheet for removing the adhesive layer 3 from the base sheet 2 by peeling off, so preferably its thickness is 20 microns or greater, more preferably 30 microns or greater, and the breaking strength is 20 MPa or greater, more preferably 30 MPa or greater, more preferably 50 MPa or greater.

With the above-mentioned second intermediate layer 9, after the laminate 1 is irradiated, a laminate of the second intermediate layer 9/adhesive layer 3'/light-transmitting carrier 5 is obtained. Therefore, the second intermediate layer 9 acts as a backing when separating the adhesive layer 3' and the carrier 5, and can easily separate the two. Therefore, by providing the second intermediate layer, the light-to-heat conversion layer 4 or the adhesive layer 3' (pressure-sensitive adhesive) can be prevented from remaining on the light-transmitting carrier 5, and the carrier 5 can be easily reused. In order to remove the adhesive layer 3' from the carrier 5 by peeling it off after the laser irradiation, it is preferred that the second intermediate layer 9 has a thickness of 20 microns or more, more preferably 30 microns or greater, and its breaking strength is 20 MPa or greater, more preferably 30 MPa or greater, more preferably 50 MPa or greater. In some cases, the resin of the second intermediate layer 9 will penetrate into the light-to-heat conversion layer 4, such as when the second intermediate layer is coated in the form of a photocurable oligomer and monomer mixture and cured with ultraviolet light ( For example, the sheet is manufactured by coating a light-to-heat conversion layer on a film substrate, coating a second intermediate layer on the light-to-heat conversion layer and curing it, and coating an adhesive layer on the second intermediate layer hour). In these cases, in order to prevent rebonding of the separated surfaces due to the formation of voids by laser irradiation, the Tg of the resin (for photocurable resins, the Tg of the cured resin) must be 40°C or higher .

Manufacturing Laminates

When manufacturing a laminate, it is important to prevent undesirable impurities such as air from entering between layers. For example, if air enters between the layers, the thickness of the laminate becomes non-uniform, and the substrate to be ground cannot be ground into a thin substrate. When producing the laminate shown in FIG. 1( a ), the following methods can be considered. Firstly, the coating solution of the precursor of the light-to-heat conversion layer is coated on the carrier by any of the above methods, irradiated with ultraviolet light or similar radiation, dried and cured. Then, an adhesive layer is coated on one or both surfaces of the cured light-to-heat conversion layer and on the non-abrasive surface of the substrate. The light-to-heat conversion layer and the substrate are bonded through an adhesive layer, and then the adhesive layer is cured by ultraviolet light irradiation from the carrier side, thereby forming a laminated body. Such laminates are preferably formed under vacuum to prevent air from entering between the layers. For example, this can be achieved by modifying the vacuum bonding apparatus described in Japanese Unexamined Patent Publication (Kokai) No. 11-283279. When manufacturing a laminate as shown in Fig. 1(b) to (e), the laminate can be conveniently formed by laminating the substrate to be ground and the carrier using a double-sided adhesive tape preformed by a conventional method . This is likewise preferably carried out under vacuum conditions similar to those described above. In the laminate shown in Fig. 1(f), the adhesive layers 3 and 3' are all pressure-sensitive adhesive layers, which can be produced in the same way as in Fig. 1(b) to (e) laminate, that is, in A double-sided coated adhesive tape with a pressure-sensitive adhesive is formed on both surfaces of an intermediate layer/light-to-heat conversion layer/second intermediate layer, and a substrate to be polished and a carrier are laminated thereon. In this case, the second intermediate layer is coated directly on the light-to-heat conversion layer and fixed to the carrier with an adhesive layer 3' (pressure-sensitive adhesive or photocurable adhesive). When the adhesive layers 3 and 3' are photocurable adhesives, the laminated body can be produced in the same manner as the laminated body shown in Fig. 1(a). Vacuum bonding equipment that can be used to form the laminate is described below.

It is preferable that the laminate is designed so that the water used will not enter when the substrate is ground, its interlayer adhesive strength will not cause the substrate to drop, and its wear resistance prevents the light-to-heat conversion layer from being contaminated by particles containing the dust of the ground substrate. Water flow (slurry) abrasion.

Fabricate Thin Substrates

The method for manufacturing a thinned substrate includes: preparing the laminate formed above, grinding the substrate to a required thickness, applying radiant energy to the light-to-heat conversion layer through a light-transmitting carrier, and decomposing the light-to-heat conversion layer, thereby changing from the light-transmitting The ground substrate is separated from the carrier, and the adhesive layer is peeled off from the substrate.

In one aspect, the method of the present invention is described below with reference to the accompanying drawings. Hereinafter, a laser beam is used as a radiation energy source, and a silicon wafer is used as a substrate to be polished, but the present invention is not limited thereto.

Fig. 2 is a sectional view of a vacuum bonding apparatus suitable for manufacturing a laminate in one example of the present invention. Vacuum bonding equipment 20 comprises vacuum chamber 21; Be arranged on the support member 22 in vacuum chamber 21, place a substrate 2 (silicon wafer) or carrier 5 to be ground on the support member; Be arranged on the fixing/relaxing device in vacuum chamber 21 23 , the device can move vertically on the upper part of the supporting part 22 to clamp another carrier 5 or silicon wafer 2 . The vacuum chamber 21 is connected with a decompression device 25 through a pipeline 24, so that the pressure in the vacuum chamber 21 can be reduced. The fixing/releasing device 23 has a shaft 26 movable up and down in the vertical direction, a contact surface part 27 arranged at the end of the shaft 26, a spring piece 28 arranged on the periphery of the contact surface part 27, and protrudes from each spring piece 28. The fixed claw 29. As shown in FIG. 2( a ), when the leaf spring contacts the upper surface of the vacuum chamber 21 , the leaf spring is compressed, and the fixing claws 29 face the vertical direction to clamp the outer edge of the carrier 5 or wafer 2 . On the other hand, as shown in Fig. 2 (b), when the shaft 26 is depressed, the carrier 5 or the wafer 2 is very close to the wafer 2 or the carrier 5 respectively located on the supporting member, the fixing claw 29 is released, and the The spring piece 28 is used to superimpose the carrier 5 and the wafer 2 together.

Using this vacuum bonding apparatus 20, a laminate can be produced as described below. First, as described above, the light-to-heat conversion layer is placed on the carrier 5 . Additionally prepare the wafers to be laminated. An adhesive is applied to one or both of the wafer 2 and the light-to-heat conversion layer of the carrier 5 to form an adhesive layer. The carrier 5 and wafer 2 thus prepared are placed in the vacuum chamber 21 of the vacuum bonding device 20 shown in FIG. 26. Wafers are laminated, and after passing through the air, the adhesive is cured if necessary to obtain a laminate.

Figure 3 is a partial cross-sectional view of a grinding apparatus usable in one example of the present invention. The grinding device 30 includes a base 31 and a grinding wheel 33 rotatably fixed on the bottom end of a spindle 32 . There is a suction port 34 under the base 31 , and the suction port 34 is connected with a decompression device (not shown), thereby sucking the material to be ground and fixing it on the base 31 of the grinding device 30 . A laminated body 1 of the present invention as shown in FIG. 1 was prepared as a material to be ground. The carrier side of the laminate 1 is mounted on the base 31 of the grinding device 30 and fixed by suction using a decompression device. Grinding is then performed by bringing the rotating grinding wheel 33 into contact with the laminate 1 while entering a stream of liquid such as water or any known solution that can be used for wafer grinding. Grinding may be performed to an ultrathin level of 150 microns or less, preferably 50 microns or less, more preferably 25 microns or less.

After grinding until required, the laminated body 1 is taken out and conveyed to the next process in which the wafer and the carrier are separated by irradiation with a laser beam and the adhesive layer is peeled off from the wafer. Figure 4 shows the process of separating the carrier and peeling off the adhesive layer. First, considering the final dicing process, if necessary, a die-bonding tape 41 (FIG. 4(a)) or no die-bonding tape (FIG. 4(a')), followed by placement of dicing tape 42 and dicing frame 43 (Fig. 4(b)). Subsequently, irradiation of a laser beam 44 is performed from the carrier side of the laminate 1 ( FIG. 4( c )). After the laser beam irradiation, the carrier 5 is picked up, and the carrier 5 is separated from the wafer 2 (FIG. 4(d)). Finally, the adhesive layer 3 is peeled off to obtain a thinned silicon wafer 2 ( FIG. 4( e )).

A bevel cut called chamfering is usually performed on semiconductor wafers such as silicon wafers to prevent the edges from being damaged by impact. That is, the corners of the edge portion of the wafer are rounded. When using a liquid adhesive as the adhesive layer and coating by spin coating, the adhesive layer is applied on the edge portion so that the adhesive is exposed on the edge portion of the abrasive surface. As a result, when the dicing tape is applied, not only does the abrasive wafer come into contact with the pressure sensitive adhesive of the dicing tape, but also the exposed adhesive. If the dicing tape used is very adhesive, it is sometimes difficult to separate the adhesive layer. In this case, it is preferable to pre-remove partially exposed adhesive prior to placement of the dicing tape and dicing frame. For removing the exposed adhesive at the edge portion, it is effective to use radiant energy or a CO ₂ laser (wavelength 10.6 micron) that is sufficiently absorbed by the adhesive.

Fig. 5 is a cross-sectional view of a laminate fixing device that can be used in the process using a laser beam or the like in the present invention. The laminated body 1 is mounted on the fixing plate 51 so that the carrier becomes the upper surface opposite to the fixing device 50 . The fixing plate 51 is made of porous metal such as sintered metal or metal with surface roughness. The pressure is reduced from the lower portion of the fixing plate 51 using a vacuum device (not shown), whereby the laminated body 1 is fixed on the fixing plate 51 by suction. The vacuum suction is preferably strong enough not to drop it in the subsequent process of separating the carrier and peeling off the adhesive layer. The laminate fixed in this way is irradiated with a laser beam. In order to emit a laser beam, the output of the selected laser beam source should be high enough to cause the thermally decomposable resin in the light-to-heat conversion layer to decompose at the wavelength of light absorbed by the light-to-heat conversion layer, so that decomposition gas will be generated, which can Separate the carrier and wafer. For example, YAG laser (wavelength is 1064 nm), second harmonic YAG laser (wavelength is 532 nm) and semiconductor laser (wavelength is 780 to 1300 nm) can be used.

A device that can scan the laser beam, form a required pattern on the irradiated surface, and can set the laser output and the moving speed of the laser beam is selected as the laser irradiation device. Furthermore, in order to stabilize the processing quality of the irradiated material (laminate), equipment with a large depth of focus is chosen. The depth of focus varies depending on the dimensional accuracy of device design, and there is no particular limitation on the depth of focus, but it is preferably 30 micrometers or more. Fig. 6 is a perspective view of laser irradiation equipment usable in the present invention. The laser irradiation device 60 of accompanying drawing 6 (a) is equipped with a galvanometer, and its biaxial configuration is composed of an X axis and a Y axis, and its design enables the laser beam oscillating from the laser oscillator 61 to be galvanometered by the Y axis. It is reflected by the X-axis galvanometer 62, further reflected by the X-axis galvanometer 63, and irradiated on the laminate 1 on the fixed plate. The irradiation position is determined according to the orientation of the galvanometers 62 and 63 . The laser irradiation apparatus 60 of FIG. 6(b) is equipped with a uniaxial galvanometer or polygon mirror 64 and a stage 66 movable in a direction orthogonal to scanning. A laser beam emitted from a laser oscillator 61 is reflected by a galvanometer or polygon mirror 64 , further reflected by a fixed mirror 65 , and irradiated onto the laminated body 1 on a movable stage 66 . The irradiation position is determined by the orientation of the galvanometer or polygon mirror 64 and the position of the movable platform 66 . In the apparatus of FIG. 6( c ), a laser oscillator 61 is mounted on a movable platform 66 which moves in the biaxial directions of X and Y, and laser light is irradiated on the entire surface of the laminated body 1 . The device in FIG. 6( d ) includes a fixed laser oscillator 61 and a platform 66 that can move in the X and Y directions. The composition of Fig. 6 (e) equipment is, laser oscillator 61 is installed on the movable platform 66 ', and this platform can move in single-axis direction, laminated body 1 is placed on movable platform 66 ", and this platform Can move in a direction normal to the movable platform 66'.

When there is concern that the wafers of the laminate 1 will be damaged by laser irradiation, it is preferable to form a top hat shape (see Fig. 6(f)) of the radiant energy, which has a steep energy distribution, energy leakage to adjacent areas very low. The laser beam form can be altered by any known method, such as (a) using an acousto-optic device to deflect the energy beam, refraction/diffraction to form the laser beam, or (b) using a pinhole or slit in the The method of truncating the widened part at both edges.

Laser irradiance energy is determined by laser power, laser beam scanning speed and beam diameter. For example, laser powers of 0.3 to 100 watts (W), but not limited to this range, scan speeds of 0.1 to 40 meters per second (m/s), and beam diameters of 5 to 300 microns or greater can be used. To speed up the process, the laser power can be increased, resulting in faster scanning. Since the number of scans can be further reduced as the beam diameter becomes larger, the beam diameter can be increased when the laser power is sufficiently high.

The thermally decomposable resin in the light-to-heat conversion layer decomposes due to laser irradiation, producing a gas that generates cracks in the layer, allowing the light-to-heat conversion layer to separate by itself. If air enters between the cracks, rebonding of the cracks can be avoided. Therefore, it is preferable to scan the laser beam from the edge portion of the laminated body toward the inside of the laminated body in order to facilitate air entry.

As described above, the glass transition temperature (Tg) of the light-to-heat conversion layer is preferably room temperature (20° C.) or higher. This is because cracks that have separated may rebond to each other as the decomposed resin cools, making separation impossible. It is considered that the rebonding occurs due to the cracks of the light-to-heat conversion layer being bonded to each other under the weight of the carrier. Therefore, rebonding can be prevented when the irradiation process is designed so that the weight of the carrier is not applied, for example, laser irradiation in a vertical direction from bottom to top (i.e. laser irradiation in a configuration with the carrier as the bottom surface) Alternatively, a hook is inserted between the wafer and the light-to-heat conversion layer from the edge portion, and the layer is lifted.

To use the laser beam from the edge portion of the laminate, an application method of reciprocating the laser beam in a straight line from the edge portion to the tangential direction of the wafer may be used, or a laser beam may be irradiated spirally from the edge portion to the central portion in a manner similar to playing a record Methods.

After laser irradiation, the carrier is separated from the wafer, and a conventional vacuum picker is used for this operation. The extractor is a cylindrical part connected to a vacuum device with a suction device at the end. Figure 7 is a schematic diagram of the lifter used for the separation of wafer and carrier operations. In FIG. 7( a ), the lifter 70 is located at the center of the carrier 5 and picks up in a vertical direction, thereby peeling off the carrier. In addition, as shown in Fig. 7 (b), pick-up 70 is positioned at the edge portion of carrier 5, blows a stream of compressed air (A) from side while peeling off, makes it enter between wafer 2 and carrier 5, can more The carrier is easily peeled off.

After removing the carrier, the adhesive layer on the wafer is removed. Accompanying drawing 8 is a schematic diagram of how to peel off the adhesive layer. For removing the adhesive layer 3 , it may be preferable to remove the adhesive layer using an adhesive tape 80 capable of producing a stronger bond with the adhesive layer 3 than between the wafer 2 and the adhesive layer 3 . The adhesive tape 80 is placed and bonded on the adhesive layer 3, and then peeled off in the direction indicated by the arrow, so that the adhesive layer 3 can be removed.

What remains is the ground thin wafer secured on dicing tape or a die cut frame, with or without die bonding tape. The wafer is sliced according to a conventional method to complete chips. However, sectioning can be performed prior to laser irradiation. In this case, it is also possible to carry out the dicing process while the wafer and the carrier are still bonded, and then irradiate the laser beam only to the diced area, and separate the carrier only at the diced portion. The present invention is also suitable for performing the slicing process independently without using the dicing tape, and only needs to transfer the grinding wafer to the light-transmitting carrier with the light-to-heat conversion layer thereon through the adhesive layer.

The present invention is effective in the following applications.

1. Laminated CSP (Chip Scale Package) for high-density packaging

The present invention can form a stacked multi-chip package with a device called system-in-package, and accommodate a large number of large-scale integration (LSI) devices and passive components in a single system-in-package, which can realize multi-function or high performance. According to the method of the present invention, wafers of 25 microns or less can be reliably fabricated for these devices with high yield.

2. Straight-through CSP that requires high performance and high speed processing

In this device, chips are connected through through electrodes, which shortens wiring length and improves electrical performance. In order to solve technical problems such as forming via holes for through electrodes and embedding copper in the via holes, it is necessary to further reduce the chip thickness. When sequentially forming a chip with such a structure using the laminate of the present invention, it is necessary to form an insulating film and protrusions (electrodes) on the back of the wafer, and the lamination requires resistance to heat and chemicals. When the above-mentioned support, light-to-heat conversion layer and adhesive layer are selected, the present invention can be effectively applied even in this case.

3. Ultra-thin compound semiconductors (such as GaAs) with improved thermal radiation efficiency, electrical properties, and stability

Compound semiconductors such as gallium arsenide are used in high-performance discrete chips, laser diodes, etc. because of their superior electrical properties (high electron mobility, direct transition band structure) compared to silicon. Using the laminated body of the present invention can reduce the chip thickness, improve its heat dissipation efficiency, and improve its performance. Currently, lapping operations for thickness reduction and electrode formation are performed by bonding a semiconductor wafer to a glass substrate as a carrier using grease or a protective material. Therefore, this bonding material must be able to be dissolved by a solvent to separate the wafer from the glass substrate after processing. The problem with this method is that the separation takes many days and the waste must be disposed of. These problems can be solved when using the laminated body of this invention.

4. Applied to large wafers to increase yield

For large wafers (eg, 12 inch diameter silicon wafers), easy separation of the wafer from the carrier is important. When the laminate of the present invention is used, separation can be easily performed, and therefore, the present invention can also be used in this field.

5. Ultra-thin quartz wafer

In the field of quartz wafers, it is required to reduce the thickness of the wafer to increase the oscillation frequency. When the laminate of the present invention is used, separation can be easily performed, and therefore, the present invention can also be used in this field.

The present invention will be described in more detail below with reference to Examples.

First, using various laser irradiation conditions, optimal conditions for separating the carrier and the wafer were evaluated. Since the nature of the separation depends on the degree of decomposition of the light-to-heat conversion layer when it is irradiated with laser light, a glass substrate is used instead of a ground wafer. A 127 millimeter (mm) x 94 mm x 0.7 mm glass substrate was used as the light-transmitting carrier, and the same glass substrate as above was used instead of the wafer. A 10% solution (in propylene glycol methyl ether acetate solvent) of a light-to-heat conversion layer precursor having the composition shown in Table 1 below was coated on a glass substrate by spin coating.

Table 1: Light-to-heat conversion layer

the Solid content ratio EC600JD 15.91% Solasperse 5000 0.80% Disperbyk 161 12.78% UR8300 39.81% Ebecryl EB629 11.64% TMPTA-N 11.64% Irgacure 369 6.47% Irgacure 184 0.96% Total 100.00%

EC600JD (Ketjen Black International Co.): carbon black, average particle size 30 nanometers; Solsperse 5000 (Zeneca Co., Ltd.): dispersion aid Disperbyk 161 (BYK ChemieJapan Co., Ltd.): dispersant (in butyl acetate 30% in toluene/methyl ethyl ketone); UR8300 (Toyobo Co., Ltd.): urethane-modified polyester resin (30% in toluene/methyl ethyl ketone), MW=30000, Tg=23°C, Breaking strength of 400 kg/cm2, elongation at break of 500%; Ebecryl EB629 (Daicel UCB Co.Ltd.): phenolic resin varnish epoxy acrylate diluted to 33% with monomer (TMPTA), oligomer MW=550.

TMPTA-N (Daicel UCB Co.Ltd.): Trimethylolpropane triacrylate Irgacure 369 (Ciba Specialty Chemicals K.K.): 2-Benzyl-2-N, N-dimethylamino-1-(4-mol and Irgacure 184 (Ciba Specialty Chemicals K.K.): 1-hydroxycyclohexyl phenyl ketone.

Heat (80° C., 2 minutes) to make it dry, and then cure with ultraviolet (UV) radiation to form a light-to-heat conversion layer on the carrier. An adhesive layer precursor having the composition shown in Table 2 below was drop-coated on another glass substrate. These substrates were laminated to each other, subjected to ultraviolet radiation, and the adhesive layer precursor was cured, thereby obtaining a laminated body.

Table 2: Adhesive layers

the Solid content ratio UV-6100B 57.10% HDODA 38.10% Darocure1173 4.80% Total 100.00%

UV-6100B (Nippon Synthetic Chemical Industry Co., Ltd): Acrylated urethane oligomer, MW = 6700, Tg after UV curing is 0°C; HDODA (Daicel UCB): 1,6-hexanediol Diacrylate; Darocure 1173 (Ciba Specialty Chems.): 2-Hydroxy-2-methyl-1-phenylpropan-1-one.

The structure of this laminate is glass substrate/light-to-heat conversion layer/adhesive layer/glass substrate, the thickness of the light-to-heat conversion layer is 0.9 microns, and the thickness of the adhesive layer is 100 microns. This laminate was placed on the fixing plate of the laminate fixing device shown in Fig. 4, the pressure was reduced from the lower side using a vacuum device, and the laminate was fixed on the fixing plate by suction. A YAG laser (with a wavelength of 1064 nm) was used as the laser beam source of radiant energy. The laser output varies from 0.52 to 8.00 watts, the beam diameter and scan line spacing are the same, and varies from 90 to 200 microns, and the laser scanning speed varies from 0.2 to 5 m/s, from the edge part of the laminate The laser beam is applied linearly and reciprocally, and the laser beam is irradiated on the entire surface of the laminate.

A pressure sensitive adhesive tape (SCOTCH ^™ Pressure Sensitive Adhesive Tape, #3305 available from 3M Company, St. Paul, MN) was stuck on the laminate glass substrate thus irradiated with the laser beam, and then picked up.

Through this preliminary test, it was found that when the laser output is 6.0 to 8.0 watts, the beam diameter and scanning line spacing are 100 to 200 microns, and the laser scanning speed is 0.2 to 2.0 m/s, the effect of separating the glass substrate is good.

Example 1:

A glass substrate of 220 mm (diameter) x 1.0 mm (thickness) was used as a light-transmitting carrier, and a silicon wafer of 200 mm (diameter) x 750 microns (thickness) was used as a wafer. A 10% solution (in propylene glycol methyl ether acetate solvent) of a light-to-heat conversion layer precursor having the composition shown in Table 1 above was coated on a glass substrate by spin coating. It is heated and dried, and then cured with ultraviolet (UV) radiation to form a light-to-heat conversion layer on the carrier. Adhesion layer precursors having the compositions shown in Table 2 above were also coated on the wafers by spin coating. The glass substrate and the wafer were laminated together in the vacuum bonding apparatus shown in FIG. 2, and then irradiated with ultraviolet light to cure the adhesive layer precursor, thereby obtaining a laminated body. The structure of the laminate is glass substrate/light-to-heat conversion layer/adhesive layer/silicon wafer, the thickness of the light-to-heat conversion layer is 0.9 microns, the thickness of the adhesive layer is 100 microns, and the adhesive area is 314 square centimeters.

The obtained laminated body was placed in the grinding apparatus shown in Fig. 3, and while a stream of water was input, the rotating grinding wheel was brought into contact with the laminated body to perform grinding. Grind to a wafer thickness of 50 µm. Then place a dicing tape and a dicing frame on the grinding surface of the wafer, transfer the laminate to the fixing plate of the laminate fixing device shown in Figure 5, use a vacuum device to decompress from the lower side, and use suction to make the layer The pressing body is fixed on the fixing plate.

According to the above preliminary test results, YAG laser (wavelength of 1064 nm) was used for laser irradiation, the laser output was 6.0 watts, the beam diameter and scanning line spacing were both 100 μm, and the laser scanning speed was 1.0 m/s. The laminate is irradiated with a linearly reciprocating laser beam from an edge portion of the laminate toward a tangential direction. In this way the entire surface of the laminate is irradiated. The glass plate holding the irradiated laminate is picked up by a suction device equipped with it, and the glass plate can be easily separated from the wafer to produce a wafer with an adhesive layer thereon.

When peeling the adhesive layer from the wafer, stick a pressure-sensitive adhesive tape (SCOTCH ^™ #3305 Wafer De-taping Tape available from 3M) on the surface of the adhesive layer and peel it off in a direction of 180° so as not to damage the wafer. In the case of obtaining a silicon wafer with a thickness of 50 μm.

Example 2

In this example, the test was carried out in the same manner as in Example 1, except that the following changes were made. A 20% solution (in propylene glycol methyl ether acetate) having a solid content ratio composition shown in Table 3 below was used as a light-to-heat conversion layer precursor. Moreover, in order to prevent rebonding due to the weight of the glass substrate during laser irradiation, an L-shaped hook should be inserted at the edge portion of the glass substrate and hung with a spring, thus preventing Rebonding occurs due to the weight of the glass substrate. Similar to Example 1, a silicon wafer having a thickness of 50 micrometers can be obtained without destroying the wafer.

Table 3: Light-to-heat conversion layer

the Solid content ratio Raven 760 27.64% Disperbyk 161 13.82% Ebecryl 8804 50.49% Irgacure 369 7.00% Irgacure 184 1.05% Total 100.00%

Raven 760 (Columbian Carbon Japan Ltd.): carbon black; Disperbyk 161 (BYKChemie): dispersant (30% in butyl acetate); Ebecryl 8804 (Daicel UCB): aliphatic urethane diacrylate, MW =1400 (30% in toluene); Irgacure 369 (Ciba Specialty Chemicals K.K.): 2-benzyl-2-N, N-dimethylamino-1-(4-morpholinophenyl)-1-butane Ketone; Irgacure 184 (also available from Ciba): 1-hydroxycyclohexyl phenyl ketone.

Example 3:

In this example, the test was carried out in the same manner as in Example 2, except that a 10% solution (in propylene glycol methyl ether acetate) having the composition of the solid content ratio shown in Table 4 below was used as the light-to-heat conversion layer precursor. The light-to-heat conversion layer precursor is a polymer solution containing carbon black, so the light-to-heat conversion layer can only be formed by a drying method.

Table 4: Light-to-heat conversion layer

the Solid content ratio Raven 760 30.06% Disperbyk 161 15.03% UR8300 54.91% Total 100.00%

Raven 760 carbon black; Disperbyk 161 dispersant; UR8300 polyurethane polyester.

By the same operation as in the example, a silicon wafer having a thickness of 50 micrometers can be obtained without destroying the wafer.

Comparative example 1:

Carry out the test in the same manner as in Example 1, the difference is that the light-to-heat conversion layer is not used when preparing this laminate composed of silicon wafer/pressure-sensitive adhesive tape/glass substrate, and double-sided pressure-sensitive adhesive is used Tape (SCOTCH ^™ #9415 High Tack/Low Tack) replaced the adhesive layer, allowing the lower tack adhesive to contact the wafer. Silicon wafers cannot be peeled off.

Embodiments 4 to 10:

The following tests were carried out in the same manner as in Examples 1 to 3, changing the composition and thickness of the light-to-heat conversion layer, and using the same composition as the adhesive (high elastic modulus type adhesive) used in Examples 1 to 3 Or an adhesive having the following composition (low elastic modulus type adhesive). The thickness of the adhesive layer was 50 microns. Grind silicon wafers to a thickness of 25 microns. The composition and thickness of the light-to-heat conversion layer and the composition of the adhesive layer in each example are shown in Tables 5 and 6. In Examples 4 to 6, silicon oxide was incorporated as a transparent filler.

Table 5: Light-to-heat conversion layer A (containing silicon oxide)

the weight Volume Black Pearls 130 25.0% 18.6% AEROSIL 380 22.0% 13.8% Disperbyk 161 7.5% 9.4% Joncryl 690 45.5% 58.3% Total 100.0% 100.0%

Light-to-heat conversion layer B (containing silicon oxide)

the weight Volume Black Pearls 130 25.0% 17.9% AEROSIL 380 16.5% 10.0% Disperbyk 161 7.5% 9.0% Joncryl 690 51.0% 63.1% Total 100.0% 100.0%

Light-to-heat conversion layer C (containing silicon oxide)

the weight Volume Black Pearls 130 25.0% 17.3% AEROSIL 380 11.0% 6.4% Disperbyk 161 7.5% 8.7% Joncryl 690 56.5% 67.5% Total 100.0% 100.0%

Light-to-heat conversion layer D

the weight Volume Black Pearls 130 65.0% 52.4% Disperbyk 161 32.5% 26.5% Joncryl 690 2.5% 21.1% Total 100.0% 100.0%

Light-to-heat conversion layer E

the weight Volume Black Pearls 130 45.0% 32.4% Disperbyk 161 22.5% 16.3% Joncryl 690 32.5% 51.3% Total 100.0% 100.0%

Adhesive layer A (low elastic modulus)

the weight UV 6100B 38.1% HDODA 25.4% HOA-MS 31.7% Irgacure 369 4.8% Total 100.0%

Adhesive layer B (high modulus of elasticity)

the weight UV 6100B 57.1% HDODA 38.1% Irgacure 369 4.8% Total 100.0%

Light-to-heat conversion layer material:

Black Pearls 130 (Cabot Corporation) carbon black; EC600JD carbon black; AEROSIL 380 (Nippon Aerosil Co.) silica filler; Joncryl 690 (Johnson Polymer Co.); polyacrylate resin, acid value = 240, MW = 15500, Tg =102°C; Disperbyk 161 (BYK ChemieJapan Co., Ltd): dispersant; Solsperse 5000 (Zeneca Co., Ltd): dispersant.

Adhesive layer material:

UV-6100B (The Nippon Synthetic Chemical Industry Co., Ltd): Acrylated urethane oligomer, MW = 6700, Tg after UV curing is 0 ° C; HDODA (DaicelUCB Company Ltd.): 1,6- Hexylene glycol diacrylate; HOA-MS (Kyoeisha Chemical Co., Ltd) 2-acryloyloxyethyl succinic acid; Irgacure 369 (Ciba Specialty Chemicals K.K.) 2-benzyl-2-N, N-dimethyl amino-1-(4-morpholinophenyl)-1-butanone.

Table 6:

In each example, two samples were prepared, one using a high elastic modulus adhesive as the adhesive layer and the other using a low elastic modulus adhesive as the adhesive layer.

For testing, the wafer and glass substrate were separated according to the procedure described in Example 1. The test results are shown in Table 7 below.

Table 7: Force required to separate laminate from glass

*1: Value measured at a wavelength of 365 nm.

*2: The modulus of elasticity at 25°C is 320 MPa.

*3: The modulus of elasticity at 25°C is 10 MPa.

*4: FVC (Filler Volume Concentration); TFVC (Top Filler Volume Concentration), which can be determined from the void volume of the filler in a dry state, using the amount of liquid (oil absorption) required to fill the voids of the above filler.

*5: The wafer and carrier can be easily separated by preventing re-adhesion.

As can be seen from the above table, when the high elastic modulus type adhesive layer was used, the glass substrate and the 25 micron wafer were all easily separated in Examples 4 to 10. When the low elastic modulus type adhesive layer was used, the glass substrate and the wafer were not easily separated in Examples 6 and 8 to 10, and FVC/TFVC in these Examples was 80% or less. In Example 8, FVC/TFVC was 80% or more, but since the thickness of the light-to-heat conversion layer was small (0.3 micrometers), rebonding would occur because the adhesive layer was partially exposed to the separation surface, requiring a larger big force. In Examples 6 and 8 to 10, in the same manner as in Examples 2 and 3, the same method of preventing rebonding as described in Examples 2 and 3 (hanging it with an L-shaped hook and a spring) is adopted. ) to prepare the test sample again and conduct the test. At this time, the glass substrate and the 25 µm wafer could be easily separated. In Examples 4 and 5, using not only carbon black but also silicon oxide, even if the FVC/TFVC is 80% or more, about 2% of the ultraviolet (365 nm) transmittance can be secured, and the short-term Time-cured adhesive layers using UV-curable adhesives.

Examples 11 to 14 (adhesive layers preferred in certain embodiments)

In these examples, the laminates of the present invention were produced using materials composed of light-to-heat conversion layers and adhesives shown in the table below.

Table 8

Adhesive layer 1

chemical name Product name weight% urethane acrylate UV7000B 28.6% urethane acrylate UV6100B 28.6% 1,6-Hexanediol diacrylate 1,6-HX-1 38.1% photochemical reaction initiator Irgacure 369 4.8% Total the 100.0%

Adhesive layer 2

chemical name Product name weight% urethane acrylate UV7000B 47.6% Dicyclopentyl acrylate FA513A 19.0% 1,6-Hexanediol diacrylate 1,6-HX-A 28.6% photochemical reaction initiator Irgacure 369 4.8% Total the 100.0%

Table 9: Adhesive Layer 3

chemical name Product name weight% urethane acrylate UV6100b 57.1% 1,6-Hexanediol diacrylate 1,6-HX-A 38.1% photochemical reaction initiator Irgacure 369 4.8% Total the 100.0%

Table 10: Light-to-heat conversion layer

chemical name Product name weight% carbon black Sevacarb 25.0% Silica A200 32.5% Dispersant Disperbyk 16 7.5% Acrylic resin Joncryl 690 35.0% Total the 100.0%

Adhesive material:

UV-6100B (The Nippon Synthetic Chemical Industry Co., Ltd.) Acrylated urethane oligomer, MW=6700, Tg after UV curing is 0°C and UV-7000B (also available from Nippon Synthetic Chem.) Acrylated urethane oligomer, MW=3500, Tg after UV curing: 52°C; 1,6-HX-A (Kyoeisha Chemical Co., Ltd.); FA513A (Hitachi Chemical Co., Ltd.) ; HOA-MS (Kyoeisha Chemical Co., Ltd.); DCPA (Kyoeisha Chemical Co., Ltd.); Irgacure 369 (Ciba Specialty Chemicals K.K.).

Light-to-heat conversion layer material:

Sevacarb (Columbian Carbon Japan Ltd.); Aerosil 200 (Nippon Aerosil Co.); Joncryl 690 (Johnson Polymer Co.); Disperbyk 161 (BYK Chemie Japan Co., Ltd.).

When measuring the storage modulus of Adhesives 1 to 3, a sample size of 22.7 mm x 10 mm x 50 μm was used in tension mode at a frequency of 1 Hz, a strain of 0.04%, and a heating rate of 5 °C/min. A SOLIDS ANALYZER RSA II obtained from Rheometrics, Inc. was used. The results are shown in Table 11. The elastic modulus at 50°C is shown in the table, assuming that the highest temperature during grinding is 50°C. Furthermore, the table also shows the minimum elastic modulus measured at 25 to 180°C.

In order to verify the adhesive strength of the adhesive as an adhesive layer, the adhesive strength (cleavage mode) of each adhesive was measured according to the following method. As shown in FIG. 9 , a silicon wafer 92 is fixed on a horizontal support table 91 by strong pressure-sensitive adhesive double-sided coated tape. An adhesive layer (adhesive 1) with an area of 3.5 square centimeters was coated on the silicon wafer 92, dried and photocured to form an adhesive layer 93 with a thickness of 50 microns. An L-shaped measuring jig 94 with a contact area of 3.5 cm2 was bonded on the cured adhesive layer 93 by a pressure-sensitive adhesive double-coated tape. A metal wire is connected to the vertical end of the L-shaped measuring jig 94, a weight 95 is suspended, a tensile force is applied in the horizontal direction, and the weight is moved at a pulling speed of 20 mm/min. The load at break is the adhesive strength (split mode) shown in Table 11. Furthermore, a pre-heat treatment (140°C, 3 minutes) was performed to restore the adhesive strength. The adhesive strength after the previous heat treatment is also shown in Table 11.

Example 11:

The glass substrate coated with the light-to-heat conversion layer was laminated with a silicon wafer through an adhesive 1 with a thickness of 50 micrometers and cured with ultraviolet light. The bonding area was 314 square centimeters. The wafer face of the laminated sample was ground to a wafer thickness of 25 μm with a grinder under the condition of supplying grinding water, and then the damaged layer (approximately 2 μm) was removed using a dry polishing device. Die-bonding tape was used to simulate thermocompression bonding, and the fabricated samples were placed on a hot plate at 180°C for 3 minutes. Also, laser irradiation was performed from the glass side, the glass substrate was removed, and then the adhesive was peeled off. The grinding conditions are as follows.

(1) Grinding equipment: Model DFG850E manufactured by DISCO

(2) Grinding conditions:

the kibble final grinding wafer thickness 750 to 60 microns 60 to 25 microns Wheel number (JIS#) 380 2000 The number of revolutions per minute of the grinding wheel (rev/min) 4800 5500

Example 12:

The test was carried out in the same procedure as in Example 11, except that Adhesive 2 was used, and after lamination, the pre-grinding sample was placed in an oven at 140° C. for 3 minutes as a pre-heat treatment.

Example 13:

The same procedure as in Example 11 was used for the test, except that Adhesive 3 was used and the thickness of the adhesive was changed to 25 microns.

Example 14:

The test was performed using the same procedure as in Example 11, except that Adhesive 3 was used and the ground final thickness of the wafer was changed to 50 microns.

As can be seen from Table 11, even when grinding was carried out under the same conditions as conventional grinding to 150 µm, there was no problem of edge chipping or water entering the interface between the wafer and the adhesive layer during grinding. A sufficiently high adhesive strength can be obtained after the pre-heat treatment, and there is no problem that the adhesive layer cannot be separated from the wafer because the adhesive strength of the adhesive layer increases after the pre-heat treatment. This shows the damage that remains on the wafer after removal (such as chemical etching using chemicals, CMP using slurry for mechanical and chemical polishing, or dry polishing using no chemicals at all). There is also no edge breakage or peeling when the layer is damaged by grinding rather than the single crystal.

Examples 15 and 16 (laminates with additional layers):

In these examples, laminates containing a first intermediate layer and a second intermediate layer were produced.

The following were used as the light-to-heat conversion layer, second intermediate layer, pressure-sensitive adhesive, photocurable adhesive, light-transmitting support (glass substrate) and substrate to be ground.

Table 12: Light-to-heat conversion layer

chemical name Product name weight% carbon black Sevacarb 25.0% Silica A200 32.5% Dispersant Disperbyk 16 7.5% Acrylic resin Joncryl 690 35.0% Total the 100.0%

Table 13: Second Intermediate Layer

chemical name Product name weight% urethane acrylate UV7000B 47.6% Dicyclopentyl acrylate FA513A 47.6% photochemical reaction initiator Irgacure 369 4.8% Total the 100.0%

Table 14: Pressure Sensitive Adhesives

chemical name Product name weight% polyurethane polyester UR8700 25.0% polyurethane polyester UR3200 75.0% Total the 100.0%

Glass substrate: TENPAX heat-resistant glass

Table 15: Photocurable Adhesives

chemical name Product name weight% urethane acrylate UV6100B 57.1% 1,6-Hexanediol diacrylate 1,6-HX-A 38.1% photochemical reaction initiator Irgacure 369 4.8% Total the 100.0%

Material to be ground: silicon wafer with a thickness of 750 microns.

Raw material (precursor):

Sevacarb (Columbian Carbon Japan Ltd.); Aerosil 200 (Nippon Aerosil Co.); Disperbyk 161 (BYK Chemie Japan Co., Ltd.); Joncryl 690 (Johnson Polymer Co.); .); FA513A (Hitachi Chemical Co., Ltd.); 1,6-HX-A (Kyoeisha Chemical Co., Ltd.); Irgacure 369 (Ciba Specialty Chemicals K.K.); UR8700: Urethane-modified polyester Resin, MW=32000, Tg=-22°C. Breaking strength < 100 kg/cm2, elongation at break 1000%; UR3200: urethane modified polyester resin, MW = 40000, Tg = -3 °C, breaking strength < 100 kg/cm2, elongation at break Elongation rate 700% (both obtained from Toyobo Co., Ltd.).

Example 15:

a) Preparation of laminate

On the polyethylene terephthalate (PET) film (TEIJIN O Film, manufactured by Tejin Ltd.) (corresponding to an intermediate layer in Fig. 1 (f)) of 50 micrometers, coat the photothermal conversion layer (1 micron) and dried, on which an intermediate layer (corresponding to the second intermediate layer 9 in Figure 1(f)) (30 microns) was applied and dried. Furthermore, a pressure-sensitive adhesive (10 µm) was coated thereon to make a pressure-sensitive adhesive single-coated tape. Then, the adhesive tape and the glass substrate were laminated using a roller to obtain a glass substrate/pressure-sensitive adhesive layer/second intermediate layer/light-to-heat conversion layer/PET film (first intermediate layer).

Alternatively, a silicon wafer is coated with a photocurable adhesive. Then, the silicon wafer was laminated on the exposed PET film of the glass substrate/pressure sensitive adhesive layer/second interlayer/light-to-heat conversion layer/PET film (first interlayer) fabrication by photocurable adhesive on the surface, and from the glass substrate side, to cure the adhesive with UV light. The bonded area of the laminate was 314 square centimeters.

b) Back grinding

The silicon wafers in the laminate were back ground to 50 microns.

c) Separation of glass substrates

The laminated surface of the lapped wafer was pasted on dicing tape and then fixed on a vacuum chuck table. Then, the entire surface was irradiated from the side of the glass substrate using a YAG laser (output: 7 W, wavelength: 1064 nm) to separate the glass substrate and the pressure-sensitive adhesive/second intermediate from the PET film (first interlayer) layer.

d) Separate the adhesive layer

A pressure sensitive adhesive tape (SCOTCH ^™ #3305, available from 3M) was adhered to the exposed surface of the first interlayer (PET film) and pulled upward to remove the film and adhesive layer from the wafer substrate.

e) Separation of the pressure sensitive adhesive and the second intermediate layer

A pressure sensitive adhesive tape (#3305) was adhered to the exposed surface of the second interlayer and pulled upward to remove the interlayer and pressure sensitive adhesive in its entirety from the glass substrate.

result:

It was demonstrated that the adhesive layer and film could be removed together from the wafer surface without breaking the adhesive layer. No residual glue or the like was observed on the wafer surface.

It has also been demonstrated that the interlayer and pressure sensitive adhesive can be integrally removed from the surface of the glass substrate. The glass substrate can be reused after being washed with ethanol and pure water.

Example 16:

A laminate was produced and tested in the same manner as in Example 15, except that a multilayer optical film (3M ^™ Solar Reflecting Film, available from 3M) was used instead of the PET film.

result:

It was demonstrated that the adhesive layer and film could be removed together from the wafer surface without breaking the adhesive layer. No residual glue or the like was observed on the wafer surface.

It has also been demonstrated that the interlayer and the pressure sensitive adhesive can be entirely removed from the surface of the glass substrate. The glass substrate can be reused after being washed with ethanol and pure water. Moreover, since the multilayer optical film used transmits light required for curing the photocurable adhesive to form an adhesive layer and reflects laser light required for radiant energy treatment, the adhesive layer can be cured without any problem, And at the same time, it can protect the circuit pattern on the chip so that it will not be damaged by laser light.

Using the laminate according to the invention it is possible to detach substrates ground to very thin from the carrier without damaging the substrate. By separating the carrier and the substrate by radiation energy such as a laser beam, the adhesive layer can be easily peeled off from the substrate, and an ultra-thin substrate can be manufactured without damaging the substrate.

Claims (16)

1. A laminate comprising: substrate to be ground; an adhesive layer in contact with the substrate; a light-to-heat conversion layer located below the adhesive layer, which contains a light absorber and a thermally decomposable resin; and a light-transmitting carrier located below the light-to-heat conversion layer; The radiation energy applied to the light-to-heat conversion layer causes thermal decomposition of the thermally decomposable resin, and the gas generated by the thermal decomposition divides the light-to-heat conversion layer into two parts, thereby separating the carrier and the substrate; The thermally decomposable resin is selected from: polyurethane, polyester, polyorthoester, polyvinylpyrrolidone, copolymer of vinylidene chloride and acrylonitrile, silicone resin, block copolymer containing polyurethane unit, or combination. 2. Laminate according to claim 1, characterized in that said substrate is a brittle material. 3. The laminate according to claim 1, wherein said substrate is a silicon wafer. 4. The laminate of claim 1, wherein the light absorbing agent comprises carbon black. 5. The laminated body according to claim 1, characterized in that the light-to-heat conversion layer further contains a transparent filler. 6. The laminate according to claim 5, wherein the transparent filler is silicon oxide. 7. The laminated body according to claim 5, wherein the light absorbing agent is carbon black, and the total amount of the carbon black and the transparent filler in the light-to-heat conversion layer accounts for 5 to 70% of volume. 8. The laminated body according to claim 5, wherein the light absorbing agent is carbon black, and the total amount of the carbon black and the transparent filler in the light-to-heat conversion layer is 80% of the highest filler volume concentration. %Or more. 9. The laminated body according to claim 1, wherein said light-to-heat conversion layer contains carbon black in an amount of 5 to 70% by volume of said light-to-heat conversion layer. 10. The laminate of claim 1, wherein the carrier is glass. 11. The laminate of claim 1, wherein said adhesive layer is a light-curable adhesive. 12. The laminated body of claim 1, further comprising a first intermediate layer between the adhesive layer and the light-to-heat conversion layer. 13. The laminate of claim 12, wherein the first intermediate layer is a multilayer optical film. 14. The laminate according to any one of claims 1 to 13, characterized in that a second intermediate layer is located between the light-to-heat conversion layer and the light-transmitting carrier, and the second intermediate layer and the The light-transmitting carrier is bonded by another adhesive layer. 15. A method of manufacturing a laminate as claimed in any one of claims 1 to 14, said method comprising: Coating a solution containing a light absorbing agent and a thermally decomposable resin or a light-to-heat conversion layer precursor of a monomer or oligomer as a precursor material of the thermally decomposable resin on the light-transmitting carrier; drying, hardening or curing the light-to-heat conversion layer precursor, forming a light-to-heat conversion layer on the light-transmitting carrier; applying an adhesive to the substrate to be polished or the light-to-heat conversion layer to form an adhesive layer; and The substrate to be polished and the light-to-heat conversion layer are bonded through the adhesive layer under reduced pressure to form a laminated body. 16. A method of making a thin substrate comprising: preparing a laminate as claimed in any one of claims 1 to 14; Grinding the substrate to a required thickness; irradiating the light-to-heat conversion layer through the light-transmitting carrier to decompose the light-to-heat conversion layer, thereby separating the substrate and the light-transmitting carrier after grinding; and The adhesive layer is peeled from the substrate after grinding.

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