JP2013072066A - Temporary fixing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temporary fixing material which enables highly precise processing while reducing damages on a substrate and which enables detachment of the substrate from a support substrate after processing at an appropriate heating temperature.SOLUTION: In order to process a semiconductor wafer (substrate) 3, the temporary fixing material is used for temporarily fixing the semiconductor wafer 3 on a support substrate 1 and detaching the semiconductor wafer 3 from the support substrate 1 by heating after processing of the semiconductor wafer 3. The temporary fixing material contains a polycondensate of a polycarboxylic acid and a compound having at least two hydroxy groups, and an activator.

Description

  The present invention relates to a temporary fixing material, and more particularly to a temporary fixing material used for temporarily fixing the base material to a supporting base material when the base material is processed.

In order to perform processing such as polishing and etching on the semiconductor wafer, it is necessary to temporarily fix the semiconductor wafer temporarily on a base material for supporting the semiconductor wafer.
Various methods have been proposed for temporarily fixing a semiconductor wafer on a substrate. For example, at present, a method of fixing a semiconductor wafer on a fixing film in which an adhesive layer is provided on a PET film as a base material is often used.
In this method, when the grinding accuracy (about 1 μm) of a general back grinding machine used for grinding is combined with the thickness accuracy (about 5 μm) of a general back grinding (BG) tape for fixing a semiconductor wafer, There is a problem that the required thickness accuracy is exceeded and the thickness of the ground wafer varies.
In addition, when processing a semiconductor wafer used for through silicon vias, via holes and films are formed with a BG tape attached, and the temperature at that time reaches at least about 150 ° C., This will increase the adhesive strength of the BG tape. Further, the adhesive layer of the BG tape is eroded by the plating chemicals for film formation, and peeling may occur.
In addition, since a fragile semiconductor wafer typified by a compound semiconductor may be damaged by mechanical grinding, it is thinned by etching. In this etching, there is no particular problem as long as the etching amount is for the purpose of removing stress. However, when etching is performed by several μm, the BG tape may be deteriorated by the etching chemical.
On the other hand, a method of fixing a semiconductor wafer to a supporting substrate having a smooth surface via a fixing material has been adopted.
For example, in order to perform etching for the purpose of stress removal, it is necessary to heat to a high temperature, but PET film cannot withstand such a high temperature. In such a case, a method using a supporting substrate Is preferably applied.
As the fixing material to the supporting base material, a fixing material that is softened at a high temperature to facilitate detachment of the semiconductor wafer and a fixing material that is dissolved by a specific chemical solution have been proposed.
However, such materials are poor in handling, and it is necessary to wash the fixing material remaining inside the semiconductor wafer or the apparatus with a chemical solution or the like after detachment.
Further, when the semiconductor wafer is detached from the support base, the thinned semiconductor wafer may not be able to withstand and may be damaged, but this possibility is expected to increase as the semiconductor wafer becomes thinner.
Although the purpose of use is different from that of the present invention, for example, Patent Document 1 and Patent Document 2 disclose polymers relating to the manufacture of semiconductor devices.
When such a polymer is used as a fixing material, the polymer is decomposed by heating to a high temperature, and as a result, the thinned semiconductor wafer can be easily detached from the support substrate.

JP-T-2006-504853 JP-T-2006-503335

  An object of the present invention is to provide a temporary fixing material capable of performing high-precision processing while reducing damage to the base material and capable of detaching the base material from the support base material after processing at an appropriate heating temperature. It is to provide.

Such an object is achieved by the present invention described in the following [1] to [8].
[1] Temporarily fixing the base material to the supporting base material for processing the base material, and temporarily fixing the base material to be detached from the supporting base material by heating after processing the base material A temporary fixing material comprising a polycondensate of a polyvalent carboxylic acid and a compound having at least two hydroxyl groups and an activator as essential components.
[2] The number-average molecular weight of the polycondensate of the polyvalent carboxylic acid and the compound having at least two hydroxyl groups is 1.6 × 10 ^{4 to} 2.5 × 10 ^4. Fixed material.
[3] The temporary fixing material according to [1] or [2], wherein the polycondensate of the polyvalent carboxylic acid and the compound having at least two hydroxyl groups has a glass transition temperature of 50 to 90 ° C.
[4] The temporary fixing material according to any one of [1] to [3], wherein the polycondensation product of a polycarboxylic acid and a compound having at least two hydroxyl groups has a branched branch.
[5] The temporary fixing material according to any one of [1] to [4], wherein the temporary fixing material is detached from the base material without being decomposed by the heating of the temporary fixing material.
[6] The temporary fixing material according to any one of [1] to [5], wherein a 1% weight reduction temperature of the temporary fixing material in a thermal decomposition measurement is 250 ° C. or higher.
[7] The shear strength between the base material and the temporary fixing material after the base material is fixed to the supporting base material by heating using a temporary fixing material is compared with the shear strength after the fixing and irradiation with active energy rays. The temporary fixing material according to any one of [1] to [6], which is high.
[8] After irradiation with active energy rays, the shear strength between the base material and the temporary fixing material after fixing the base material to the supporting base material by heating using a temporary fixing material is 0.1 to 50 kPa. [1] Thru | or the temporary fixing material in any one of [7].

  The temporary fixing material of the present invention can be processed with high accuracy while reducing damage to the base material, and has an effect that it can be detached from the support base material after processing at an appropriate heating temperature.

It is a longitudinal cross-sectional view for demonstrating the process process which processes the semiconductor wafer etc. which are base materials using the temporary fixing material of this invention.

  In the present specification, the support base material is a hard substrate having flatness for supporting the substrate, and examples of the support base material include a glass substrate, a silicon substrate, and a metal substrate.

  The substrate refers to a semiconductor component having a semiconductor circuit or an electric circuit, or an electric / electronic component. Examples of the substrate include a semiconductor wafer, a semiconductor chip, and a capacitor.

In the method for manufacturing a semiconductor device of the present invention, when a semiconductor wafer (substrate) is fixed to a glass substrate (support base material) or a silicon substrate (support base material) and the semiconductor wafer is subjected to back surface processing or TSV processing, It can be used for manufacturing a semiconductor package having a fan-out structure.
Hereinafter, the temporary fixing material of the present invention will be described in detail.

<Temporary fixing material>
The temporary fixing material of the present invention is characterized by comprising a polycondensate of a polyvalent carboxylic acid and a compound having at least two hydroxyl groups and an activator as essential components.
As described above, the temporary fixing material of the present invention is heated to a temperature range of about 90 to 200 ° C. to be in a molten state, and easily does not cause damage such as cracks in the processed substrate. Can be done.
The temporary fixing material of the present invention includes a resin component that generates an acid or a base in the resin composition constituting the temporary fixing material, and a resin component whose shear strength decreases when heated, and the active energy ray. By containing an activator that generates an acid or a base by irradiation, the shear strength can be lowered after irradiation with active energy rays, and the temporary fixing material and the substrate can be easily peeled off.
Hereinafter, each component of the resin composition that can be used for the temporarily fixing material will be sequentially described.

(Polycondensate)
The polycondensate of the polyvalent carboxylic acid and the compound having at least two hydroxyl groups used in the present invention (hereinafter sometimes simply referred to as “polycondensate”) is not particularly limited, but the number average molecular weight is 1 .6 is preferably × a ^{10 4 ~2.5} × ¹⁰ 4.
Thereby, processing with high accuracy is possible, and in addition to appropriately performing cleaning after desorption from the support base material, it has moderate heat resistance.

The polycondensate preferably has a glass transition temperature of 50 to 90 ° C.
As a result, processing with high accuracy is possible while reducing damage to the support substrate, and in addition to appropriately performing detachment from the support substrate after processing, it has moderate heat resistance. .
Moreover, the adhesiveness at the time of temporary fixing increases.
More preferably, it is 55-85 degreeC, More preferably, it is 60-83.
If it is in the said range, a highly accurate process can be performed at a higher level and it is excellent also in adhesiveness.

The polycondensate preferably has a branched branch.
As a result, processing with higher accuracy is possible while reducing damage to the base material, and in addition to further appropriately detaching the base material after processing from the support base material, further optimal heat resistance is achieved. It will have.

The method for producing the polycondensate is not particularly limited. For example, a direct polymerization method or a transesterification method in which a polyvalent carboxylic acid and a compound having at least two hydroxyl groups are directly esterified and polymerized under normal pressure or pressure. And a known method such as a method of adding a small amount of xylene and dehydrating at normal pressure.
As the polymerization catalyst, known catalysts such as a titanium compound such as tetrabutyl titanate shown in this embodiment, a zinc compound, an antimony compound, a tin compound, and a germanium compound are used.

The polyvalent carboxylic acid is not particularly limited, and any polycarboxylic acid having two or more carboxyl groups in the molecule may be used. The polyvalent carboxylic acid may be fumaric acid having two carboxylic acid groups. Butane-1 having three carboxylic acid groups, such as malonic acid, adipic acid, terephthalic acid, isophthalic acid, sebacic acid, dodecanedioic acid, diphenyl ether-4,4'-dicarboxylic acid, pyridine-2,6-dicarboxylic acid , 2,4-tricarboxylic acid, cyclohexane-1,2,3-tricarboxylic acid, benzene-1,2,4-tricarboxylic acid, naphthalene-1,2,4-tricarboxylic acid, etc., butane having four carboxylic acid groups -1,2,3,4-tetracarboxylic acid, cyclobutane-1,2,3,4-tetracarboxylic acid, benzene-1,2,4,5-tetracar Phosphate, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, 3,3', 4,4'-diphenyl ether tetracarboxylic acid and the like, aliphatic carboxylic acids, and unsaturated carboxylic acid.

The polycondensate with the compound having at least two hydroxyl groups is not particularly limited, but diethylene glycol, 1,4-butanediol, propylene glycol, 1,4-cyclohexanedimethanol polyol, glycerin, trimethylolpropane, pentaerythritol, etc. Can be mentioned.

(Active agent)
The temporary fixing material of the present invention contains an activator as an essential component. The temporary fixing material of the present invention includes an activator that generates active species by applying energy by irradiation with active energy rays, and the 50% weight reduction temperature of the resin component described above is lowered in the presence of the active species. Is preferred. Thereby, the damage to a base material can be reduced more reliably.

The activator is not particularly limited, and examples thereof include a photoacid generator and a photobase generator.

The photoacid generator is not particularly limited, and examples thereof include tetrakis (pentafluorophenyl) borate-4-methylphenyl [4- (1-methylethyl) phenyl] iodonium (DPI-TPFPB), tris (4-t- Butylphenyl) sulfonium tetrakis- (pentafluorophenyl) borate (TTBPS-TPFPB), tris (4-t-butylphenyl) sulfonium hexafluorophosphate (TTBPS-HFP), triphenylsulfonium triflate (TPS-Tf), bis ( 4-tert-butylphenyl) iodonium triflate (DTBPI-Tf), triazine (TAZ-101), triphenylsulfonium hexafluoroantimonate (TPS-103), triphenylsulfonium bis (par Fluoromethanesulfonyl) imide (TPS-N1), di- (pt-butyl) phenyliodonium, bis (perfluoromethanesulfonyl) imide (DTBPI-N1), triphenylsulfonium, tris (perfluoromethanesulfonyl) methide ( TPS-C1), di- (pt-butylphenyl) iodonium tris (perfluoromethanesulfonyl) methide (DTBPI-C1), and the like, and one or a combination of two or more of these can be used. . Among these, tetrakis (pentafluorophenyl) borate-4-methylphenyl [4- (1-methylethyl) phenyl] iodonium (DPI), particularly from the viewpoint that the thermal decomposition temperature of the resin component can be efficiently lowered. -TPFPB) is preferred.

The photobase generator is not particularly limited, and examples thereof include 5-benzyl-1,5-diazabicyclo (4.3.0) nonane, 1- (2-nitrobenzoylcarbamoyl) imidazole, and the like. 1 type or 2 types or more can be used in combination. Among these, 5-benzyl-1,5-diazabicyclo (4.3.0) nonane and derivatives thereof are particularly preferable from the viewpoint that the thermal decomposition temperature of the resin component can be efficiently lowered.

The activator is preferably about 0.01 to 50% by weight, more preferably about 0.1 to 30% by weight of the total amount of the temporary fixing material.
By setting it within such a range, it is possible to stably lower the shear strength between the temporary fixing material and the base material within the target range.
By adding such an activator, an active energy ray is irradiated to generate an active species such as an acid or a base, and heating in the presence of this active species, the main chain of the resin component of the temporary fixing material It is presumed that a structure in which the shear strength decreases is formed.
Therefore, in addition to the case where an active species such as an acid or a base is generated, the same effect can be obtained in the case of radical cleavage by irradiation with active energy rays or ion detachment.
As the activator used for radical cleavage, a known compound can be used as long as it can radically cleave the polyester resin. For example, the temporary fixing material may contain a radical polymerization initiator such as benzoyl peroxide. It ’s fine.
As the activator used in the case of ion detachment, a known compound can be used as long as the polyester resin is ion detached. For example, sodium sulfate, sodium sulfite, potassium sulfate, magnesium sulfate can be used as a temporary fixing material. As long as it does not deteriorate the performance.
The temporarily fixed material of the Example shown below becomes low in shear strength of a temporarily fixed material by light irradiation compared with before light irradiation.

(solvent)
Moreover, the temporary fixing material may contain a solvent.
Examples of the solvent include, but are not limited to, hydrocarbons such as mesitylene, decalin, and mineral spirits, alcohols such as anisole, propylene glycol monomethyl ether, dipropylene glycol methyl ether, diethylene glycol monoethyl ether, and diglyme. / Ethers, ethylene carbonate, ethyl acetate, N-butyl acetate, ethyl lactate, ethyl 3-ethoxypropionate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene carbonate, γ-butyrolactone, etc./lactones, Examples include ketones such as cyclopentanone, cyclohexanone, methyl isobutyl ketone, 2-heptanone, and amides / lactams such as N-methyl-2-pyrrolidone. It is, can be used singly or in combination of two or more of them. When the temporarily fixing material contains a solvent, it becomes easy to adjust the viscosity of the temporarily fixing material, and it becomes easy to form a temporarily fixing material layer (thin film) composed of the temporarily fixing material on the support base material.

Although content of the said solvent is not specifically limited, It is preferable that it is 5-98 weight% of the whole quantity of a temporary fixing material, and it is more preferable that it is 10-95 weight%.

(Sensitizer)
Furthermore, the temporary fixing material may contain a sensitizer that is a component having a function of developing or increasing the reactivity of the active agent together with the active agent. Sensitizers can broaden the range of wavelengths where the activator can be activated, and as an optimal sensitizer, it has a maximum extinction coefficient near the light source used, making the absorbed energy efficient It is a compound that can be passed to the photoacid generator. In particular, when the light source has a wavelength such as g-line (435 nm) and i-line (365 nm), the sensitizer is effective for activating the photoacid generator.
Although it does not specifically limit as a sensitizer, When a photoacid initiator is included, for example, 2-isopropyl-9H-thioxanthen-9-one, 4-isopropyl-9H-thioxanthen-9-one 1-chloro-4-propoxythioxanthen-9-one, phenothiazine or a combination thereof.
Such a sensitizer is added in a range that does not directly affect the photothermal reaction of the resin. The content of the sensitizer is preferably 100 parts by weight or less, and more preferably 20 parts by weight or less, with respect to 100 parts by weight of the total amount of activators such as the photoacid generator described above.

(Antioxidant)
Moreover, the temporarily fixing material may contain antioxidant.
This antioxidant has a function of preventing generation of acid in the temporary fixing material and natural oxidation of the resin composition.
The antioxidant is not particularly limited. For example, “Ciba IRGANOX (registered trademark) 1076” and “Ciba IRGAFOS (registered trademark) 168” manufactured by Ciba Fine Chemicals are preferably used.

Other antioxidants include, for example, “Ciba Irganox 129”, “Ciba Irganox 1330”, “Ciba Irganox 1010”, “Ciba Cyanox (registered trademark) 1790”, “Ciba Irganox 3114 C” Can also be used.

The content of the antioxidant is preferably 0.1 to 10 parts by weight and more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the temporary fixing material (resin component) described above. .

(Additive)
In addition, the temporary fixing material may contain an acid scavenger, an acrylic, silicone, fluorine, vinyl or other leveling agent, an additive such as a silane coupling agent or a diluent, if necessary.

The silane coupling agent is not particularly limited. For example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p -Styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxy Silane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltri Ethoxysilane 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxypropyl) Examples thereof include tetrasulfide and 3-isocyanatopropyltriethoxysilane, and among these, one kind or two or more kinds can be used in combination.
By including the silane coupling agent in the temporary fixing material, it is possible to improve the adhesion between the base material and the support base material.

The diluent is not particularly limited, and examples thereof include cycloether compounds such as cyclohexene oxide and α-pinene oxide, aromatic cycloethers such as [methylenebis (4,1-phenyleneoxymethylene)] bisoxirane, 1, Examples thereof include cycloaliphatic vinyl ether compounds such as 4-cyclohexanedimethanol divinyl ether, and one or more of these can be used in combination.
By including the diluent in the temporarily fixing material, the fluidity of the temporarily fixing material can be improved, and in the temporary fixing material layer forming step described later, the wettability of the temporarily fixing material to the supporting base material can be improved. It becomes.

In addition, at the time of heating for desorbing the base material from the supporting base material, from the viewpoint of preventing the diffusion of the temporary fixing material into the atmosphere, that is, the contamination of the atmosphere by the temporary fixing material, The temporary fixing material is preferably present between the base material and the supporting base material without being vaporized in the atmosphere.
Therefore, the 1% weight reduction temperature of the temporarily fixed material after irradiating the temporarily fixed material with active energy rays is preferably 250 ° C. or higher, and more preferably 280 ° C. or higher.
More preferably, it is 310 degreeC or more, Most preferably, it is 330 degreeC or more.
Thereby, the spreading | diffusion of the temporary fixing material in the atmosphere at the time of the said heating can be suppressed or prevented exactly.
In the present specification, the 1% weight loss temperature means that the weight of 1% resin component when the temperature is increased from 30 ° C. to 500 ° C. at a rate of 10 ° C./min under heating in a nitrogen atmosphere is lost. The range of heating temperature until the decomposition of the resin component starts and ends, in other words, the start temperature at which the decomposition of the resin component starts and the end temperature at which the decomposition of the resin component ends (completes) Are measured using a thermogravimetric analysis method (hereinafter sometimes referred to as TG / DTA), and obtained based on the result.
Specifically, first, a resin component dissolved in propylene glycol monomethyl ether acetate is applied onto a silicon substrate using a spin coating method, and then the solvent is evaporated by baking at about 150 ° C. for 10 minutes on a heating plate. . Next, the thin film (sample) composed of the resin component formed on the silicon substrate is analyzed by TG / DTA which is increased from 30 ° C. to 500 ° C. at 10 ° C./min in a nitrogen atmosphere.
And it is possible to obtain _| require the temperature at the time of 1% weight loss of the temporary fixing material (resin composition) measured in this TG / DTA as 1% weight reduction temperature ( _Td50 ).

Moreover, when processing the base material temporarily fixed to the base material with the temporary fixing material, if the shear stress of the temporary fixing material is reduced, the adhesive strength between the temporary fixing material and the supporting base material is reduced, and these A positional shift may occur, which may reduce the yield of the semiconductor device.
Therefore, it is preferable that the higher the shear strength of the temporarily fixing material, the higher the adhesive strength. The shear strength of the base material and the temporary fixing material is preferably 10 to 350 kPa at 175 ° C. More preferably, it is 15-200 kPa. More preferably, it is 20-100 kPa.
If it is in the said range, a base material can be fixed efficiently. Moreover, especially when shear strength is 20-100 kPa, there exists an effect which can peel a support base material easily after that.

<Measurement method of shear strength>
A specific method for measuring the shear strength between the temporary fixing material and the supporting substrate is as follows. It is applied onto a supporting substrate 200 mm diameter glass substrate (Tempax, manufactured by Mito Rika Glass Co., Ltd.), dried at 120 ° C. for 5 minutes on a hot plate in the atmosphere, and 40 μm thick on the glass substrate. A layer of temporary fixing material is formed. On this temporary fixing material layer, a silicon chip having a side of 10.5 mm and a thickness of 725 μm is fixed as a base material at a load of 5 N, 90 ° C., in the atmosphere for 10 seconds. Thereafter, at a temperature of 175 ° C., the shear strength is obtained by pushing the silicon chip so that the silicon chip moves relative to the glass substrate at 600 μm / second.

<Method for Manufacturing Semiconductor Device>
Next, a case where the temporarily fixing material of the present invention is applied to the manufacture of a semiconductor device will be described as an example.
That is, an embodiment applied to the processing of a semiconductor wafer in the method for manufacturing a semiconductor device will be described as an example.
For processing the semiconductor wafer (base material), a step of forming a temporary fixing material layer on the supporting base material using the temporary fixing material of the present invention, and a semiconductor on the supporting base material via the temporary fixing material layer. The step of bonding the wafer, the step of processing the surface of the semiconductor wafer opposite to the support base, and the step of removing the semiconductor wafer from the support base by heating the temporary fixing material layer are included.
FIG. 1 is a longitudinal sectional view for explaining a processing step of processing a semiconductor wafer using the temporarily fixing material of the present invention. In the following description, in FIG. 1, the upper side is “upper” and the lower side is “lower”.
Hereinafter, these steps will be sequentially described.

(Temporary fixing material layer forming process)
First, a support base material 1 is prepared, and a temporary fixing material layer 2 is formed on the support base material (base material) 1 using the temporary fixing material of the present invention (see FIG. 1A).
The temporary fixing material layer 2 can be easily formed by supplying the temporary fixing material of the present invention onto the support substrate 1 and then drying it.
The method for supplying the temporarily fixing material of the present invention onto the support substrate 1 is not particularly limited. For example, spin coating, spraying, printing, film transfer, slit coating, scan coating, etc. These various coating methods can be used. Of these, the spin coating method is particularly preferably used. According to the spin coating method, a more uniform and flat fixing agent layer 2 can be easily formed.
The supporting base material 1 is not particularly limited as long as it has a strength that can support the base material 3, but is preferably a light-transmitting material. Thereby, even if the base material 3 does not have a light transmittance, in an active energy ray irradiation process, an active energy ray is permeate | transmitted from the support base material 1 side, and an active energy ray is made to the temporary fixing material layer 2. Can be reliably irradiated.
As the support substrate 1 having optical transparency, for example, glass materials such as quartz glass and soda glass, and resin materials such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, and polycarbonate are mainly used. The board | substrate comprised as a material is mentioned.

(Lamination process)
Next, the semiconductor wafer (base material) 3 is placed on the surface of the support base material 1 on which the temporary fixing material layer 2 is provided such that the functional surface 31 is on the temporary fixing material layer 2 side. Thus, the semiconductor wafer 3 is bonded to the supporting base material 1 via the temporarily fixing material layer 2 (see FIG. 1B).
This bonding can be easily performed using an apparatus such as a vacuum press or a wafer bonder.

(Processing process)
Next, the surface (back surface) opposite to the functional surface 31 of the semiconductor wafer 3 fixed on the support substrate 1 through the temporarily fixing material layer 2 is processed.
The processing of the semiconductor wafer 3 is not particularly limited. For example, in addition to polishing the back surface of the semiconductor wafer 3 as shown in FIG. 1C, a semiconductor wafer for forming via holes in the semiconductor wafer 3 and for stress release. 3, etching of the back surface, lithography, and coating of a thin film on the back surface of the semiconductor wafer 3, vapor deposition, and the like.
In the processing of the semiconductor wafer in the present embodiment, the temporary fixing material layer forming step uses the temporary fixing material of the present invention, and the temporary fixing material having an excellent accuracy with a uniform film thickness and a smooth surface. Since the layer 2 is formed, the semiconductor wafer 3 can be processed with excellent accuracy.
In such a processing step, the temporary fixing material layer 2 is heated and undergoes a temperature history according to the type of processing as described above, and this temperature history starts the decomposition of the temporary fixing material described above. When the temperature is lower than the temperature, the temporary fixing material of the present invention is selected. In such a case, by selecting the temporarily fixing material of the present invention, the resin component is not less than the starting temperature at which decomposition of the resin component contained in the temporarily fixed material starts. It is possible to reliably prevent the decomposition. As a result, it is possible to process the back surface without causing separation between the semiconductor wafer 3 and the support substrate 1, and therefore, the processing can be performed with excellent dimensional accuracy.

(Active energy ray irradiation / heating process)
Next, as shown in FIG. 1 (d), the temporary fixing material layer 2 is irradiated with active energy rays.
Thereby, energy is provided to the active agent contained in the temporary fixing material (resin composition), and as a result, active species such as acid or base are generated from the active agent.
Moreover, it is although it does not specifically limit as an active energy ray, For example, it is preferable that it is a light ray with a wavelength of about 200-800 nm, and it is more preferable that it is a light ray with a wavelength of about 300-500 nm.
Furthermore, the amount of irradiating the active energy ray is not particularly limited, and is preferably about 1 to 2,000 mJ / cm ^2, more preferably about 10~1000mJ / cm ^2.
By setting the conditions for irradiating the active energy ray as described above, it is possible to reliably generate a sufficient amount of active species from the active agent to reduce the shear strength.
Next, as shown in FIG. 1E, the temporarily fixing material layer 2 is heated to bring the temporarily fixing material layer 2 into a molten state.
As a result, the semiconductor wafer 3 can be reliably detached from the support base material 1 in a desorption process described later.
Here, in the present invention, prior to the heating of the temporary fixing material layer 2, the temporary fixing material layer 2 is irradiated with active energy rays to generate an acid or a base. The shear strength is reduced.
Therefore, the heating temperature for bringing the temporarily fixed material layer 2 into a molten state can be set relatively low. Specifically, the heating temperature can be set to about 130 to 200 ° C. Therefore, it is possible to accurately suppress or prevent the deterioration / deterioration of the semiconductor wafer 3 due to this heating, and it is possible to shorten the time required for bringing the temporarily fixed material layer 2 into a molten state.
Here, the shear strength between the temporary fixing material and the base material after irradiation with active energy rays is not particularly limited as long as it is smaller than that before irradiation with active energy rays. The shear strength is preferably low.
Thereby, it can peel off without giving a damage to a support base material, the semiconductor wafer 3, etc.
The shear strength between the temporary fixing material and the support base material after irradiation with the active energy ray is preferably 0.1 to 50 kPa at 175 ° C. More preferably, it is 0.5-20 kPa. More preferably, it is preferably 1 to 15 kPa at 175 ° C. and 175 ° C.

(Desorption process)
Next, the semiconductor wafer 3 is detached from the support base material 1.
At this time, since the sacrificial layer 2 is in a molten state through the active energy ray irradiation / heating step, the semiconductor wafer 3 can be easily detached from the support base 1.
Here, in this specification, desorption means an operation of peeling the semiconductor wafer 3 from the support substrate 1. For example, this operation is performed in a direction perpendicular to the surface of the support substrate 1. 3, a method of detaching the semiconductor wafer 3 by sliding it horizontally with respect to the surface of the support base 1, or from one end side of the semiconductor wafer 3 as shown in FIG. Examples include a method of detaching the semiconductor wafer 3 by floating it from the support base material 1 (Note that in FIG. 1E, the temporary fixing material is attached to the support base material 1 surface and / or the functional surface 31 of the semiconductor wafer 3. Although the layer 2 remains, the temporary fixing material layer 2 is omitted in FIG.

(Washing process)
Next, the temporarily fixing material layer 2 remaining on the functional surface 31 of the semiconductor wafer 3 is cleaned.
That is, the residue of the temporary fixing material layer 2 remaining on the functional surface 31 is removed.
A method for removing this residue is not particularly limited, and examples thereof include plasma treatment, chemical immersion treatment, polishing treatment, and heat treatment.
In the present embodiment, the temporary fixing material layer 2 is formed on the support base material 1. However, the present invention is not limited to this, and the temporary fixing material layer 2 is formed on both the support base material 1 and the semiconductor wafer 3. Alternatively, the sacrificial layer 2 may be selectively formed on the semiconductor wafer 3 without forming the temporary fixing material layer 2 on the support substrate 1.
As mentioned above, although the temporarily fixed material of this invention was demonstrated based on embodiment of illustration, this invention is not limited to these.
For example, each constituent material included in the temporary fixing material can be replaced with any material that can exhibit the same function, or can be added with any structure.

Next, specific examples of the present invention will be described.
1. Preparation of Temporary Fixing Material First, temporary fixing materials of Examples 1 and 2 and Comparative Example as shown below were prepared.

[Example 1]
<Synthesis of polycondensate (A)>
In a reaction vessel equipped with a stirrer, thermometer, and cooler for outflow, 83 parts of terephthalic acid, 81 parts of isophthalic acid, 77 parts of ethylene glycol and 79 parts of neopentyl glycol are charged and esterified to 230 ° C. over 4 hours. Reaction was performed. Subsequently, the pressure in the system was gradually reduced, the initial polymerization under reduced pressure was carried out to 10 mmHg over 60 minutes, the temperature was raised to 250 ° C., and the latter polymerization was further carried out at 1 mmHg or less for 30 minutes to obtain a weight average molecular weight of 15,000. A condensate (A) was obtained. As a result of composition analysis such as NMR, the obtained polycondensate (A) has an acid component in a molar ratio of terephthalic acid / isosophthalic acid = 50/50, and a glycol component in a molar ratio of ethylene glycol / neopentyl glycol = 50/50. The glass transition temperature of the polycondensate (A) was 63 ° C.

<Preparation of temporary fixing material>
100.0 g of the obtained polycondensate (A) and 2.0 g of GSID26-1 (manufactured by Ciba Japan) as an activator (photoacid generator) were dissolved in 198.0 g of γ-butyrolactone, and the resin component concentration was 33 wt. % Temporary fixing material (1) was prepared.

[Example 2]
<Synthesis of polycondensate>
The polycondensate (B) was synthesized by a method according to the synthesis method of the polycondensate (A). As a result of composition analysis such as NMR, the obtained polyester resin (B) has an acid component in a molar ratio of terephthalic acid / isosophthalic acid = 50/50, and a glycol component in a molar ratio of ethylene glycol / neopentyl glycol = 45 / 55. The number average molecular weight of the polycondensate (B) was 22,000, and the glass transition temperature was 67 ° C.

<Preparation of temporary fixing material>
Example 1 100.0 g of the obtained polycondensate (B) and 2.0 g of GSID26-1 (manufactured by BASF Japan) as an activator (photoacid generator) were dissolved in 198.0 g of γ-butyrolactone to obtain a resin component. A temporary fixing material (2) having a concentration of 33% by weight was prepared.

[Example 3]
<Synthesis of polycondensate>
The polycondensate (C) was synthesized by a method according to the synthesis method of the polycondensate (A). As a result of composition analysis such as NMR, the obtained polycondensate (C) has a molar ratio of terephthalic acid / trimellitic acid / p-hydroxyacetic acid = 92/3/5 and a glycol component of molar ratio. Ethylene glycol / propylene glycol = 25/75. The number average molecular weight of the polycondensate (C) was 17,000, and the glass transition temperature was 82 ° C.

<Preparation of temporary fixing material>
Example 1 100.0 g of the obtained polycondensate (C) and 2.0 g of GSID26-1 (manufactured by BASF Japan) as an activator (photoacid generator) were dissolved in 198.0 g of γ-butyrolactone to obtain a resin component. A temporarily fixing material (3) having a concentration of 33% by weight was prepared.

[Comparative Example 1]
<Synthesis of polycondensate (D)>
Ethyl acetate (430 g), cyclohexane (890 g), and 5-decylnorbornene (223 g, 0.95 mol) were introduced into a well-dried reaction vessel, and dry nitrogen was passed through the system at 40 ° C. for 30 minutes to dissolve. Oxygen was removed. A solution prepared by dissolving 1.33 g (0.275 mmol) of bis (toluene) bis (perfluorophenyl) nickel in 12 g of ethyl acetate was added to the reaction system, and the above system was added at 20 ° C. to 35 ° C. over 15 minutes. Then, the system was stirred for 3 hours while maintaining the temperature.
After cooling the system to room temperature, 26 g of glacial acetic acid was dissolved in about 1500 g of pure water to which 49 g of 30% hydrogen peroxide was added, and this was added to the reaction system, and the reaction system was stirred at 50 ° C. for 5 hours. After that, stirring was stopped and the separated aqueous layer was removed. The remaining organic layer was washed by adding, stirring, and removing a mixture of 220 g of methanol and 220 g of isopropyl alcohol. Furthermore, after adding 510 g of cyclohexane and 290 g of ethyl acetate to the system and dissolving uniformly, another 156 g of methanol and 167 g of isopropyl alcohol are mixed and washed by adding to stirring to removing, Repeated twice.
180 mL of cyclohexane was added to the washed organic layer to uniformly dissolve the system, and 670 g of mesitylene was further added. Then, cyclohexane was removed by evaporation with a rotary evaporator under reduced pressure to obtain a 5-decylnorbornene addition polymer as a polycondensate (D) in a yield of 543 g of a 35% mesitylene solution.

<Preparation of temporary fixing material>
98.0 g of the resulting polycondensate (D) and 2.0 g of GSID26-1 (manufactured by BASF Japan) as an activator (photoacid generator) are dissolved, and a temporary fixing material (4% resin component concentration of 35% by weight) ) Was prepared.

[Reference Example 1]
<Preparation of temporary fixing material>
Polylactic acid PURASORB PDL 45 (manufactured by PURAC) 100.0 g, GSID26-1 (manufactured by BASF Japan) 2.0 g as an activator (photo acid generator) is dissolved in 448.0 g of γ-butyrolactone, and the resin component concentration 18 A weight percent temporary fixing material (5) was prepared.

2. Evaluation methods and evaluation results are shown in Table 1 below.

2-1 <Weight reduction temperature>
For the temporary fixing materials (1) to (5) prepared above, the TG / DTA apparatus (Seiko Instruments Inc., “Model No .: 6200 type”) is used to set the 1% weight reduction temperature of the temporary fixing material. Measurement was performed (atmosphere: nitrogen, heating rate: 10 ° C./min).

2-2 <Shear strength>
The temporary fixing materials 1 to 5 prepared above were each applied onto glass by a spin coating method and soft-baked in the atmosphere at 120 ° C. for 5 minutes. Next, the temporary fixing materials prepared in Examples 1 and 2 and Comparative Example were applied again on the glass under the same conditions, and after soft baking in the atmosphere at 120 ° C. for 5 minutes, further in the atmosphere. Hard baking was performed at 220 ° C. for 5 minutes to obtain a temporarily fixed material layer having a thickness of 50 μm. Thereafter, a semiconductor wafer is placed on the temporary fixing material layer, and the semiconductor wafer and glass are placed at 180 ° C., 5 kN, 2 minutes (Examples 1 to 3, Comparative Example 1) or 200 ° C., 10 kN through the temporary fixing material. , 5 minutes (Comparative Example 2).
Next, the semiconductor wafer was polished, and then the semiconductor wafer / glass laminate was heated in the atmosphere at 230 ° C. for 10 minutes.
The shear strength at 175 ° C. in this state was measured.
The measuring method is as follows.
(1) Shear strength before light irradiation A specific method for measuring the shear strength between the temporary fixing material and the supporting base is as follows. It is applied onto a supporting substrate 200 mm diameter glass substrate (Tempax, manufactured by Mito Rika Glass Co., Ltd.), dried at 120 ° C. for 5 minutes on a hot plate in the atmosphere, and 40 μm thick on the glass substrate. A layer of temporary fixing material is formed. On this temporary fixing material layer, a silicon chip having a side of 10.5 mm and a thickness of 725 μm is fixed as a base material at a load of 5 N, 90 ° C., in the atmosphere for 10 seconds. Thereafter, the shear strength was measured by pressing the silicon chip at 600 um / s with a simple shear measuring device (type 2252, AIKOH Engineering) so that the silicon chip moved relative to the glass substrate at a temperature of 175 ° C.
(2) Shear strength after light irradiation Before pressing the silicon chip, i-line was irradiated from the glass substrate side under the condition of 2000 mj / cm2 (i-line conversion), and then the shear strength at a temperature of 175 ° C. as above. It was measured.

2-3 <Desorption>
In the above, after irradiating the laminated body having a temporary fixing material between the semiconductor wafer and the glass with i-line from the glass side under the condition of 2000 mj / cm2 (i-line conversion), sandwiching with a hot plate of 180 ° C above and below, After vacuum adsorption, the semiconductor wafer was slid at a speed of 2.0 mm / second and detached from the glass. Thereafter, the semiconductor wafer and the glass were immersed in γ-butyrolactone while being swung for 5 minutes, and the residue of the temporary fixing material on the semiconductor wafer and the glass was removed.
As a result, in Example 1, Example 2, and Example 3, the semiconductor wafer can be detached without causing damage to the semiconductor wafer, and the temporary fixing material can be obtained by immersion in γ-butyrolactone. The residue could be removed. However, in Comparative Example 1, the semiconductor wafer could not be detached under these conditions.
The symbols in Table 1 are as follows: ○: When the semiconductor wafer can be detached without causing damage to the semiconductor wafer ×: When the semiconductor wafer cannot be detached

2-4 <Position>
In Example 1 and Reference Example 1, the temporary fixing materials 1 and 5 prepared above were each applied onto glass by a spin coating method and soft-baked in the atmosphere at 120 ° C. for 5 minutes. Next, the temporary fixing material prepared above is applied again on the glass under the same conditions, and after soft baking in the atmosphere at 120 ° C. for 5 minutes, further in the atmosphere at 220 ° C. for 5 minutes. Hard baking was performed to obtain a temporary fixing material layer having a thickness of 50 μm. Thereafter, a semiconductor wafer is set at a predetermined position on the temporarily fixing material layer, and the semiconductor wafer and glass are placed at 180 ° C. and 5 kN for 2 minutes through the temporarily fixing material (under the conditions of Example 1 and Reference Example 1). Fixed.
Next, polishing of the semiconductor wafer was performed to confirm the positional deviation.
Ten samples were prepared for each sample, and the number of samples with no displacement was confirmed.
The results are shown in Table 2.
Other evaluations were performed in the same manner as described above.

From Table 2, it was confirmed that Example 1 was not significantly displaced as compared with Reference Example 1.
This is presumably because Example 1 has higher shear strength before light irradiation than Reference Example 1.
Furthermore, the glass transition temperature is 55 ° C. or higher, and it is considered that the adhesion during temporary fixing has also increased.

DESCRIPTION OF SYMBOLS 1 Support base material 2 Temporary fixing material layer 3 Semiconductor wafer 31 Functional surface

Claims (8)

  A temporary fixing material used for temporarily fixing the base material to a supporting base material in order to process the base material, and releasing the base material from the supporting base material by heating after processing the base material. A temporary fixing material comprising a polycondensate of a polyvalent carboxylic acid and a compound having at least two hydroxyl groups and an activator as essential components. The temporary fixing material according to claim 1, wherein a number average molecular weight of the polycondensate of the polyvalent carboxylic acid and the compound having at least two hydroxyl groups is 1.6 × 10 ^{4 to} 2.5 × 10 ⁴ .   The temporary fixing material according to claim 1 or 2, wherein a glass transition temperature of the polycondensate of the polyvalent carboxylic acid and the compound having at least two hydroxyl groups is 50 to 90 ° C. The temporary fixing material according to any one of claims 1 to 3, wherein the polycondensation product of a polyvalent carboxylic acid and a compound having at least two hydroxyl groups has a branched branch.   The temporary fixing material according to claim 1, wherein the temporary fixing material is detached from the support base material without being decomposed by the heating of the temporary fixing material.   The temporary fixing material according to any one of claims 1 to 5, wherein a 1% weight reduction temperature of the temporary fixing material in pyrolysis measurement is 250 ° C or higher.   The shear strength between the base material and the temporary fixing material after fixing the base material to the supporting base material by heating using a temporary fixing material is higher than the shear strength after the fixing and irradiation with active energy rays. The temporary fixing material according to any one of claims 1 to 6, characterized in that The shear strength of the base material and the temporary fixing material after the base material is fixed to the supporting base material by heating using the temporary fixing material after irradiation with the active energy ray is 0.1 to 50 kPa. The temporarily fixing material in any one.