JP2012126799A - Temporary fixing agent, and method for processing base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temporary fixing agent the use of which can excellently precisely process a base material without generating voids in the temporary fixing agent placed between a support base material and the base material when the base material is temporarily fixed on the support base material; and to provide a method for processing a base material by using the temporary fixing agent.SOLUTION: The temporary fixing agent is used for temporarily fixing a semiconductor wafer (base material) 3 on a support base material 1 in order to process the semiconductor wafer 3, and processing the semiconductor wafer 3, and thereafter separating the semiconductor wafer 3 from the support base material 1 by heating. In the temporary fixing agent before heating, the content having a molecular weight of <5,000 in resin components contained in the temporary fixing agent is ≤4% in the resin components.

Description

  The present invention relates to a method for processing a temporary fixing agent and a substrate, and in particular, a temporary fixing agent used for temporarily fixing the substrate to a supporting substrate when the substrate is processed, and the temporary fixing agent. The present invention relates to a method for processing a substrate.

  In order to perform processing such as polishing and etching on a semiconductor wafer, it is necessary to temporarily fix the semiconductor wafer on a base material for supporting the semiconductor wafer, and various methods have been proposed. 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.

  Also, 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 180 ° 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, in recent years, a method of fixing a semiconductor wafer to a support 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 a material for fixing the base material to the supporting base material, a fixing material that softens at a high temperature and facilitates the removal of the semiconductor wafer (see, for example, Patent Document 1) has been proposed.

  However, in such a fixing material, a void is generated between the semiconductor wafer and the base material due to the fixing material undergoing a thermal history during processing such as polishing and etching on the semiconductor wafer. Therefore, unevenness occurs in the thickness direction of the fixing member made of the fixing material. For example, when the semiconductor wafer is polished, there is a problem that the thickness of the semiconductor wafer varies.

  Such a problem is not limited to the processing of semiconductor wafers, but also occurs in various substrates that are processed in a state of being fixed to a supporting substrate via a fixing member.

Special table 2010-53385 gazette

  It is an object of the present invention to process a temporary fixing agent positioned between the supporting base material and the base material without generating a void when the base material is temporarily fixed on the supporting base material to process the base material. Then, it is providing the temporary fixing agent which can process the base material excellent in the precision, and the processing method of the base material using this temporary fixing agent.

Such an object is achieved by the present invention described in the following (1) to (10).
(1) Temporarily fixing the base material to a supporting base material in order to process the base material, and then temporarily removing the base material from the supporting base material by heating after processing the base material. A fixative,
In the temporary fixing agent before heating, the resin component contained in the temporary fixing agent has a molecular weight of less than 5,000, and the content of the resin component is 4% or less in the resin component. Fixative.

  (2) In the temporary fixing agent before heating, in the resin component, the resin component has a molecular weight of more than 10,000 and less than 500,000 in the resin component (1) The temporary fixative as described in.

  (3) The temporary fixing agent according to (1) or (2), wherein the resin component is melted or vaporized by thermal decomposition and low molecular weight by the heating of the temporary fixing agent.

  (4) In the temporary fixing agent after the resin component is thermally decomposed and reduced in molecular weight, the resin component has a molecular weight of more than 1,000 and less than 10,000 in the resin component. The temporary fixing agent according to the above (3), which is 25% or less.

  (5) The resin component is the temporary fixing agent according to the above (3) or (4), in which the melt viscosity or the temperature at which vaporization is reduced by irradiation of active energy rays to the temporary fixing agent.

  (6) The resin component has a lower melt viscosity or vaporization temperature in the presence of an acid or a base, and the temporary fixative contains an acid or a base by irradiation with the resin component and the active energy ray. The temporary fixing agent according to the above (5), comprising a resin composition containing a generated active agent.

  (7) The temporary fixing agent according to (5) or (6), wherein the resin component is a polycarbonate-based resin.

(8) The resin component is the temporary fixing agent according to the above (3) or (4), in which the melt viscosity or the temperature at which vaporization is not reduced by irradiation of the active energy ray to the temporary fixing agent.
(9) The temporary fixing agent according to (8), wherein the resin component is a norbornene resin.

(10) a first step of forming a thin film composed of the temporary fixing agent according to any one of 1 to 9 on at least one of the substrate and the support substrate;
A second step of bonding the substrate and the support substrate through the thin film;
A third step of processing the surface of the substrate opposite to the supporting substrate;
And a fourth step of desorbing the base material from the support base material by heating and thinning the thin film.

  The temporary fixing agent of the present invention contains 4% or less of a resin component contained in the temporary fixing agent having a molecular weight of less than 5,000. For this reason, when the base material is fixed on the supporting base material using the temporary fixing agent and the base material is processed, the generation of voids in the temporary fixing agent can be accurately suppressed or prevented. As a result, there is an effect that the substrate can be processed with high accuracy.

It is a longitudinal cross-sectional view for demonstrating the process process which processes a semiconductor wafer using the temporary fixing agent of this invention.

Hereinafter, the temporary fixing agent and the processing method of a base material of this invention are demonstrated in detail based on suitable embodiment shown to an accompanying drawing.
First, the temporary fixing agent of this invention is demonstrated.

<Temporary fixative>
The temporary fixing agent of the present invention temporarily fixes the base material to a supporting base material in order to process the base material, and after the processing of the base material, the base material is detached from the supporting base material by heating. In the temporary fixing agent before heating, the resin component contained in the temporary fixing agent has a molecular weight of less than 5,000, and the content of the resin component is 4% or less in the resin component. It is characterized by being.

  Thus, in the temporary fixing agent of this invention, the content of the low molecular weight resin component is low in the temporary fixing agent before heating. Therefore, it is possible to accurately suppress or prevent the generation of voids in the temporary fixing agent when fixing the base material on the supporting base material using the temporary fixing agent and processing the base material. High-precision processing can be performed on the substrate.

  Such a temporary fixing agent of the present invention comprises a resin composition containing the resin component as described above.

Hereinafter, each component which comprises this resin composition is demonstrated one by one.
The resin component has a function of fixing the base material to the supporting base material at the time of temporary fixing, and is further caused by melting or vaporizing by thermal decomposition and low molecular weight by the heating of the temporary fixing agent. Thus, since the bonding strength is lowered, it has a function of allowing the substrate to be detached from the supporting substrate.

  In such a resin component, in the present invention, the content of those having a molecular weight of less than 5,000 is 4% or less in the resin component, but the content of those having a molecular weight of less than 5,000 is The details of the range will be described later.

  The resin component is not particularly limited as long as it has the above-described function, but is not limited to polycarbonate resin, polyester resin, polyamide resin, polyimide resin, polyether resin, polyurethane resin, ( Examples thereof include a (meth) acrylate resin, a norbornene resin, and a polyolefin resin, and one or more of these can be used in combination. Among these, norbornene resins, polycarbonate resins, vinyl resins and (meth) acrylic resins are preferable, and norbornene resins or polycarbonate resins are particularly preferable. These are more suitably selected as the resin component because they exhibit the above functions more remarkably.

  Although it does not restrict | limit especially as a polycarbonate-type resin, Polypropylene carbonate resin, polyethylene carbonate resin, 1, 2- polybutylene carbonate resin, 1, 3- polybutylene carbonate resin, 1, 4- polybutylene carbonate resin, cis-2, 3-polybutylene carbonate resin, trans-2,3-polybutylene carbonate resin, α, β-polyisobutylene carbonate resin, α, γ-polyisobutylene carbonate resin, cis-1,2-polycyclobutylene carbonate resin, trans- 1,2-polycyclobutylene carbonate resin, cis-1,3-polycyclobutylene carbonate resin, trans-1,3-polycyclobutylene carbonate resin, polyhexene carbonate resin, polycyclopropyl Carbonate resin, polycyclohexene carbonate resin, 1,3-polycyclohexane carbonate resin, poly (methylcyclohexene carbonate) resin, poly (vinylcyclohexene carbonate) resin, polydihydronaphthalene carbonate resin, polyhexahydrostyrene carbonate resin, polycyclohexanepropylene Carbonate resin, polystyrene carbonate resin, poly (3-phenylpropylene carbonate) resin, poly (3-trimethylsilyloxypropylene carbonate) resin, poly (3-methacryloyloxypropylene carbonate) resin, polyperfluoropropylene carbonate resin, polynorbornene Carbonate resin, polynorbornane carbonate resin, exo-polynorbornene carbonate tree Fat, endo-polynorbornene carbonate resin, trans-polynorbornene carbonate resin, cis-polynorbornene carbonate resin can be used, and one or more of these can be used in combination.

  Examples of the polycarbonate resin include polypropylene carbonate / polycyclohexene carbonate copolymer, 1,3-polycyclohexane carbonate / polynorbornene carbonate copolymer, poly [(oxycarbonyloxy-1,1,4,4- Tetramethylbutane) -alt- (oxycarbonyloxy-5-norbornene-2-endo-3-endo-dimethane)] resin, poly [(oxycarbonyloxy-1,4-dimethylbutane) -alt- (oxycarbonyloxy -5-norbornene-2-endo-3-endo-dimethane)] resin, poly [(oxycarbonyloxy-1,1,4,4-tetramethylbutane) -alt- (oxycarbonyloxy-p-xylene)] Resin and poly [(oxycal Nyloxy-1,4-dimethylbutane) -alt- (oxycarbonyloxy-p-xylene)] resin, 1,3-polycyclohexane carbonate resin / exo-polynorbornene carbonate resin, 1,3-polycyclohexane carbonate resin / endo -Copolymers, such as polynorbornene carbonate resin, can also be used.

  Furthermore, as the polycarbonate-based resin, in addition to the above, a polycarbonate resin having at least two cyclic bodies in the carbonate constituent unit can also be used.

  The number of cyclic bodies may be two or more in the carbonate structural unit, but is preferably 2 to 5, more preferably 2 or 3, and further preferably 2. By including such a number of cyclic bodies as the carbonate constituent unit, the adhesion between the supporting base material and the base material becomes excellent. Moreover, when the temporary fixing agent is heated, the polycarbonate resin is thermally decomposed to have a low molecular weight, thereby melting.

  In addition, the plurality of cyclic bodies may have a linked polycyclic structure in which the vertices are connected to each other, but a condensed polycyclic structure in which the sides of each ring are connected to each other. It is preferable. Thereby, both heat resistance as a temporary fixing agent and shortening of the thermal decomposition time when this thing melts can be made compatible.

  Furthermore, it is preferable that each of the plurality of cyclic bodies is a 5-membered ring or a 6-membered ring. Thereby, since the planarity of a carbonate structural unit is maintained, the solubility with respect to a solvent can be stabilized more.

  Such a plurality of cyclic bodies are preferably alicyclic compounds. When each cyclic body is an alicyclic compound, the effects as described above are more remarkably exhibited.

  In consideration of these, in the polycarbonate resin, as the carbonate structural unit, for example, a structure represented by the following chemical formula (1X) is a particularly preferable structure.

  In addition, the polycarbonate-type resin which has a carbonate structural unit represented by the said Chemical formula (1X) can be obtained by the polycondensation reaction of decalin diol and carbonic acid diester like diphenyl carbonate.

  In the carbonate structural unit represented by the chemical formula (1X), those derived from the carbon atom linked to the hydroxyl group of decalin diol are each decalin (that is, two cyclic bodies forming a condensed polycyclic structure). It is preferable that three or more atoms intervene between the carbon atoms that are bonded to the carbon atoms constituting and bonded to these hydroxyl groups. Thereby, the decomposability | degradability of polycarbonate-type resin can be controlled, As a result, heat resistance as a temporary fixing agent and shortening of the thermal decomposition time when this thing fuse | melts can be made compatible. Furthermore, the solubility with respect to a solvent can be stabilized more.

  Examples of such a carbonate structural unit include those represented by the following chemical formulas (1A) and (1B).

  Further, the plurality of cyclic bodies may be alicyclic compounds or may be heteroalicyclic compounds. Even when each cyclic body is a heteroalicyclic compound, the effects as described above are more remarkably exhibited.

  In this case, in the polycarbonate resin, as the carbonate structural unit, for example, one represented by the following chemical formula (2X) is a particularly preferable structure.

  In addition, the polycarbonate-type resin which has a carbonate structural unit represented by the said Chemical formula (2X) can be obtained by the polycondensation reaction of ether diol represented by the following Chemical formula (2a), and carbonic acid diester like diphenyl carbonate.

  In the carbonate structural unit represented by the chemical formula (2X), the carbon atom derived from the hydroxyl group of the cyclic ether diol represented by the chemical formula (2a) forms the cyclic ether (that is, a condensed polycyclic structure). It is preferable that three or more atoms are interposed between these carbon atoms and bonded to the carbon atoms constituting the two cyclic bodies. Thereby, both heat resistance as a temporary fixing agent and shortening of the thermal decomposition time when this thing melts can be made compatible. Furthermore, the solubility with respect to a solvent can be stabilized more.

  Examples of such a carbonate structural unit include those of the 1,4: 3,6-dianhydro-D-sorbitol (isosorbide) type represented by the following chemical formula (2A), and those represented by the following chemical formula (2B). 4: 3,6-dianhydro-D-mannitol (isomannide) type.

  The weight-average molecular weight (Mw) of the polycarbonate-based resin is preferably 1,000 to 1,000,000, and more preferably 5,000 to 800,000. By setting the weight average molecular weight to the above lower limit or more, it is possible to obtain the effect of improving the wettability with respect to the support substrate and further improving the film formability. Moreover, by setting it as the said upper limit or less, the effect that the solubility with respect to various solvents and also the fall of the melt viscosity by the heating of a temporary fixing agent are recognized more notably can be acquired.

  In addition, the polymerization method of polycarbonate-type resin is not necessarily limited, For example, well-known polymerization methods, such as the phosgene method (solvent method) or the transesterification method (melting method), can be used.

  Although it does not specifically limit as norbornene-type resin, For example, what contains the structural unit shown by the following general formula (1Y) can be mentioned.

In the formula (1Y), R ^{1 to} R ⁴ are each hydrogen, a linear or branched alkyl group having 1 to 20 carbon atoms, an aromatic group, an alicyclic group, a glycidyl ether group, the following substituent (2Y ) Moreover, m is an integer of 0-4.

In the formula (2Y), R ⁵ is hydrogen, a methyl group, or an ethyl group, and R ⁶ , R ^7, and R ⁸ are each a linear or branched alkyl group having 1 to 20 carbon atoms, linear, or Branched alkoxy group having 1 to 20 carbon atoms, linear or branched alkylcarbonyloxy group having 1 to 20 carbon atoms, linear or branched alkyl peroxy group having 1 to 20 carbon atoms, substituted or unsubstituted It is any of aryloxy groups having 6 to 20 carbon atoms. N is an integer of 0-5.

  The linear or branched alkyl group having 1 to 20 carbon atoms is not particularly limited, but is a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group. , Nonyl group, decyl group and the like.

  Among these, compatibility with various components constituting the temporary fixing agent (resin composition) and solubility in various solvents, and a butyl group having excellent mechanical properties when temporarily fixing the base material and the supporting base material, A decyl group is preferred.

  The aromatic group is not particularly limited, and examples thereof include a phenyl group, a phenethyl group, and a naphthyl group. Among these, the mechanical properties when the substrate and the supporting substrate are temporarily fixed are excellent. A phenethyl group and a naphthyl group are preferred.

  The alicyclic group is not particularly limited, but is a cyclohexyl group, norbornenyl group, dihydrodicyclopentadiethyl group, tetracyclododecyl group, methyltetracyclododecyl group, tetracyclododecadiethyl group, dimethyltetracyclododecyl group. And alicyclic groups such as trimer of ethyl group, ethyltetracyclododecyl group, ethylidenyltetracyclododecyl group, phenyltetracyclododecyl group, and cyclopentadiethyl group.

  Among these, a cyclohexyl group and a norbornenyl group, which are excellent in mechanical properties when the base material and the supporting base material are temporarily fixed, and further excellent in thermal decomposability when the temporary fixing agent is heated, are preferable.

R ⁵ in the substituent (2Y) is not particularly limited as long as it is hydrogen, a methyl group, or an ethyl group, but a hydrogen atom that is excellent in thermal decomposability during heating of the temporary fixing agent is preferable.

R ⁶ , R ⁷ and R ⁸ in the substituent (2Y) are each a linear or branched alkyl group having 1 to 20 carbon atoms, a linear or branched alkoxy group having 1 to 20 carbon atoms, Either a linear or branched alkylcarbonyloxy group having 1 to 20 carbon atoms, a linear or branched alkylperoxy group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms If so, there is no particular limitation.

  Examples of such substituents include methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, acetoxy group, propoxy group, butoxy group, methylperoxy group, isopropylperoxy group, t-butylperoxy group, phenoxy group. , A hydroxyphenoxy group, a naphthyloxy group, a phenoxy group, a hydroxyphenoxy group, a naphthyloxy group, and the like. An ethoxy group and a propoxy group are preferable.

  M in the general formula (1Y) is an integer of 0 to 4, and is not particularly limited, but 0 or 1 is preferable. When m is 0 or 1, the structural unit represented by the general formula (1Y) can be represented by the following general formula (3Y) or (4Y).

In the formulas (3Y) and (4Y), R ^{1 to} R ⁴ are each hydrogen, a linear or branched alkyl group having 1 to 20 carbon atoms, an aromatic group, an alicyclic group, a glycidyl ether group, One of the substituents (2Y).

  N in the substituent (2Y) is an integer of 0 to 5, and is not particularly limited, but n is preferably 0. When n is 0, the silyl group is directly bonded to the polycyclic ring via a silicon-carbon bond, so that both the thermal decomposability of the temporary fixing agent and the mechanical properties during processing of the substrate can be achieved.

  The structural unit represented by the general formula (1Y) is not particularly limited, but norbornene, 5-methylnorbornene, 5-ethylnorbornene, 5-propylnorbornene, 5-butylnorbornene, 5-pentylnorbornene, 5 -Hexyl norbornene, 5-heptyl norbornene, 5-octyl norbornene, 5-nonyl norbornene, 5-decyl norbornene, 5-phenethyl norbornene, 5-triethoxysilyl norbornene, 5-trimethylsilyl norbornene, 5-trimethoxysilyl norbornene, 5 It can be obtained by polymerizing norbornene-based monomers such as methyldimethoxysisilylnorbornene, 5-dimethylmethoxynorbornene, and 5-glycidyloxymethylnorbornene.

  When the norbornene monomer is polymerized, it may be polymerized with a single norbornene monomer or a plurality of norbornene monomers. Among these norbornene-based monomers, 5-butylnorbornene, 5-decylnorbornene, 5-phenethylnorbornene, 5-triethoxysilylnorbornene, and 5-glycidyloxy are excellent in mechanical properties when the substrate and the supporting substrate are temporarily fixed. Methylnorbornene is preferred.

  The norbornene-based resin is not particularly limited, and may be formed of a single structural unit represented by the general formula (1Y) or may be formed of a plurality of structural units.

  More specifically, the norbornene-based resin is polynorbornene, polymethylnorbornene, polyethylnorbornene, polypropylnorbornene, polybutylnorbornene, polypentylnorbornene, polyhexylnorbornene, polyheptylnorbornene, polyoctylnorbornene, polynonyl. Single polymer such as norbornene, polydecyl norbornene, polyphenethyl norbornene, polytriethoxysilyl norbornene, polytrimethylsilyl norbornene, polytrimethoxysilyl norbornene, polymethyldimethoxysisilyl norbornene, polydimethylmethoxynorbornene, polyglycidyloxymethyl norbornene, norbornene -Triethoxysilyl norbornene copolymer, norbornene-glycidyloxymethyl ester Borene copolymer, butylnorbornene-triethoxysilylnorbornene copolymer, decylnorbornene-triethoxysilylnorbornene copolymer, butylnorbornene-glycidyloxymethylnorbornene copolymer, decylnorbornene-glycidyloxymethylnorbornene copolymer, decyl Examples thereof include copolymers such as norbornene-butylnorbornene-phenethylnorbornene-glycidyloxymethylnorbornene copolymer.

  Among these, polybutylnorbornene, polydecylnorbornene, polytriethoxysilylnorbornene, polyglycidyloxymethylnorbornene-butylnorbornene-triethoxysilylnorbornene copolymer having excellent mechanical properties when the substrate and the supporting substrate are temporarily fixed Polymer, decylnorbornene-triethoxysilylnorbornene copolymer, butylnorbornene-glycidyloxymethylnorbornene copolymer, decylnorbornene-glycidyloxymethylnorbornene copolymer, decylnorbornene-butylnorbornene-phenethylnorbornene-glycidyloxymethylnorbornene copolymer Coalescence is preferred.

  The norbornene-based resin having the structural unit represented by the general formula (1Y) is not particularly limited, but ring-opening metathesis polymerization (hereinafter also referred to as ROMP), a combination of ROMP and hydrogenation reaction. It can be synthesized by polymerization with radicals or cations.

  More specifically, the norbornene-based resin having the structural unit represented by the general formula (1Y) is obtained by using, for example, a catalyst containing a palladium ion source, a catalyst containing nickel and platinum, a radical initiator, or the like. Can be synthesized.

  Moreover, it is preferable to mix | blend the resin component in the ratio of 10 weight%-100 weight% of the whole quantity which comprises a resin composition (when a solvent is included, the whole quantity except a solvent). More preferably, it is preferably blended at a ratio of 50% by weight or more, particularly 80% by weight to 100% by weight. By setting it to 10 weight% or more, especially 80 weight% or more, there exists an effect that the residue after thermally decomposing a temporary fixative can be reduced. Moreover, there exists an effect that a temporary fixing agent can be thermally decomposed in a short time by increasing the resin component in a resin composition.

  The resin components as described above are classified into those in which the melt viscosity or vaporization temperature is lowered in the presence of an acid or base and those in which the melt viscosity or vaporization temperature is not lowered.

  Specifically, in the presence of an acid or a base, as a resin component whose melt viscosity or vaporization temperature decreases, for example, a polycarbonate resin, a polyester resin, a polyamide resin, a polyether resin, a polyurethane resin, (Meth) acrylate resins and the like can be mentioned, and one or more of these can be used in combination. Among these, it is preferable to use a polycarbonate-based resin from the viewpoint that the melt viscosity or the vaporization temperature is more remarkably reduced. In particular, polypropylene carbonate, 1,4-polybutylene carbonate, 1,3-polycyclohexane carbonate / A polynorbornene carbonate copolymer is preferred.

  Furthermore, examples of the resin component that does not decrease the melt viscosity or vaporization temperature in the presence of an acid or a base include norbornene-based resins and polyolefin-based resins, and one or more of these are combined. Can be used.

  Therefore, when the resin component is selected such that the melt viscosity or the vaporization temperature is reduced in the presence of an acid or base, the acid or base is irradiated in the resin composition by irradiation with active energy rays. By setting it as the structure containing the active agent to generate | occur | produce, a melt viscosity or the temperature which vaporizes a resin component by irradiation of the active energy ray to a temporary fixative can be lowered | hung.

  Therefore, the temporary fixing agent (resin composition) contains a resin component whose melt viscosity or vaporizing temperature is reduced, and an active agent that generates an acid or a base by irradiation of active energy rays to the temporary fixing agent. As a result, the melt viscosity of the resin component or the temperature at which the resin component evaporates is reduced by irradiation with active energy rays. The effect that it can be performed is obtained.

  When the resin component is selected so that the melt viscosity or the vaporization temperature does not decrease in the presence of an acid or a base, the resin composition is subjected to irradiation with active energy rays to the temporary fixing agent. Even if an activator that generates a base is added, naturally, the melt viscosity of the resin component or the vaporizing temperature does not change even when the temporary fixing agent is irradiated with active energy rays.

  Hereinafter, the activator contained in the resin composition will be described when the resin component is selected to reduce the melt viscosity or vaporization temperature in the presence of an acid or a base.

(Active agent)
As described above, the activator generates an active species such as an acid or a base when energy is applied by irradiation with an active energy ray, and the action of the active species causes the melt viscosity of the resin component. Or it has the function to reduce the temperature to evaporate.

  The activator is not particularly limited, and examples thereof include a photoacid generator that generates an acid upon irradiation with active energy rays, and a photobase generator that generates a base upon irradiation with active energy rays.

  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 melt viscosity 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 melt viscosity of the resin component can be efficiently lowered.

  The activator is preferably about 0.01 to 50% by weight, and more preferably about 0.1 to 30% by weight, based on the total amount of the resin composition (temporary fixing agent). By setting it within such a range, it becomes possible to stably lower the melt viscosity of the resin component within the target range.

  By irradiating active energy rays by adding such an activator, an active species such as an acid or a base is generated, and the action of the active species lowers the thermal decomposition temperature of the main chain of the resin component. It is presumed that a structure is formed, and as a result, the melt viscosity or the vaporizing temperature of the resin component is lowered.

Here, the mechanism by which the thermal decomposition temperature is lowered when a polypropylene carbonate resin, which is a polycarbonate resin, is used as the resin component and a photoacid generator is used as the activator will be described. As shown by the following formula (1Z), first, H ⁺ derived from the photoacid generator protonates the carbonyl oxygen of the polypropylene carbonate resin, and further transitions the polar transition state to an unstable tautomeric intermediate [A ] And [B]. Next, the thermal decomposition temperature of the intermediate [A] is lowered because fragmentation as acetone and CO ₂ occurs. Further, the intermediate [B] generates propylene carbonate, and propylene carbonate forms a thermal ring-closing structure that is fragmented as CO ₂ and propylene oxide, so that the thermal decomposition temperature is lowered.

(Sensitizer)
Further, when the temporary fixing agent contains an active agent, it may contain a sensitizer that is a component having a function of expressing or increasing the reactivity of the active agent with respect to an active energy ray of a specific wavelength together with the active agent. good.

  The sensitizer is not particularly limited. For example, anthracene, phenanthrene, chrysene, benzpyrene, fluoranthene, rubrene, pyrene, xanthone, indanthrene, thioxanthen-9-one, 2-isopropyl-9H- Examples include thioxanthen-9-one, 4-isopropyl-9H-thioxanthen-9-one, 1-chloro-4-propoxythioxanthone, and mixtures thereof.

  The content of such a sensitizer is preferably 100 parts by weight or less with respect to 100 parts by weight of the total amount of the activator such as the photoacid generator and the photo radical initiator, and is 20 parts by weight or less. More preferably.

  In the resin composition as described above, in the presence of an acid or a base, the resin component is any of those having a reduced melt viscosity or vaporizing temperature and those having a melt viscosity or a vaporizing temperature that does not decrease. Alternatively, other components as shown below may be included.

(Antioxidant)
That is, the resin composition (temporary fixing agent) may contain an antioxidant.

  This antioxidant has a function of preventing acid generation and natural oxidation in the resin composition (temporary fixing agent).

  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 resin component described above.

(Additive)
Moreover, the resin composition (temporary fixing agent) may contain additives such as acid scavengers, acrylic, silicone, fluorine, and vinyl leveling agents, silane coupling agents, and diluents as 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 a silane coupling agent in the resin composition (temporary fixing agent), 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.

  When the resin composition (temporary fixing agent) contains a diluent, the fluidity of the temporary fixing agent can be improved, and the wettability of the temporary fixing agent with respect to the support base material is improved in the sacrificial layer forming step described later. It becomes possible.

(solvent)
Moreover, the resin composition (temporary fixing agent) 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 temporary fixing agent contains a solvent, it becomes easy to adjust the viscosity of the temporary fixing agent, and it becomes easy to form a sacrificial layer (thin film) composed of the temporary fixing agent 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 resin composition (temporary fixing agent), and it is more preferable that it is 10-95 weight%.

<Method for Manufacturing Semiconductor Device>
The temporary fixing agent of the present invention as described above is applied to a method for manufacturing a semiconductor device, for example.

  That is, the substrate processing method of the present invention is applied to the processing of a semiconductor wafer in the semiconductor device manufacturing method.

Hereinafter, an example of the embodiment of the processing method of the substrate of the present invention will be described.
For processing the semiconductor wafer (base material), a first step of forming a sacrificial layer (thin film) composed of the temporary fixing agent of the present invention on at least one of the base material and the support base material, A second step of bonding the support base and the semiconductor wafer through the sacrificial layer, a third step of processing the surface of the semiconductor wafer opposite to the support base, and thermal decomposition by heating the sacrificial layer And a fourth step of detaching the semiconductor wafer from the support base.

  FIG. 1 is a longitudinal sectional view for explaining a processing step of processing a semiconductor wafer using the temporary fixing agent of the present invention. In the following description, in FIG. 1, the upper side is “upper” and the lower side is “lower”.

Hereinafter, each of these steps will be described sequentially.
(Sacrificial layer formation process)
First, a support base material 1 is prepared, and a sacrificial layer 2 is formed on the support base material (base material) 1 using the temporary fixing agent of the present invention as shown in FIG. Step 1).

  The sacrificial layer 2 can be easily formed by supplying the temporary fixing agent of the present invention onto the support substrate 1 and then drying it.

  In addition, the method for supplying the temporary fixing agent of the present invention onto the support substrate 1 is not particularly limited, and examples thereof include a spin coating method, a spray method, a printing method, a film transfer method, a slit coating method, a scan coating method, and the like. 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 sacrificial layer 2 can be easily formed.

  Further, the supporting substrate 1 is not particularly limited as long as it has a strength that can support the semiconductor wafer 3, but it is preferable that the supporting substrate 1 has optical transparency. As a result, when a resin component whose melt viscosity or vaporization temperature is lowered by irradiation with active energy rays is used as the resin component, the active energy rays are transmitted from the support substrate 1 side to the sacrificial layer 2. It becomes possible to reliably irradiate the line.

  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, as shown in FIG. 1B, the semiconductor wafer (base material) 3 is placed on the surface on which the sacrificial layer 2 is provided on the support base material 1 so that the functional surface 31 is on the sacrificial layer 2 side. Thus, the semiconductor wafer 3 is bonded to the support base material 1 via the sacrificial layer 2 (second step).

  This bonding can be easily performed using an apparatus such as a vacuum press or a wafer bonder.

(Processing process)
Next, a surface (back surface) opposite to the functional surface 31 of the semiconductor wafer 3 fixed on the support substrate 1 through the sacrificial layer 2 is processed (third step).

  The processing of the semiconductor wafer 3 is not particularly limited. For example, in addition to grinding and polishing the back surface of the semiconductor wafer 3 as shown in FIG. 1C, for forming a via hole in the semiconductor wafer 3 and for stress release. Etching of the back surface of the semiconductor wafer 3, lithography, coating of a thin film on the back surface of the semiconductor wafer 3, vapor deposition, and the like can be given.

  When the semiconductor wafer 3 is processed on the surface opposite to the functional surface 31 as described above, the semiconductor wafer 3 undergoes a thermal history associated with this processing. Therefore, not only the semiconductor wafer 3 but also the sacrificial layer 2 is heated. As a result, a void is generated in the sacrificial layer 2 between the semiconductor wafer 3 and the support base 1. Therefore, for example, when the surface (back surface) opposite to the functional surface 31 is ground and polished in a state where such a void is generated, the thickness of the sacrificial layer 2 caused by the generation of the void is generated. There is a problem that the thickness of the semiconductor wafer 3 varies due to the presence of unevenness in the direction.

  As a result of intensive studies in view of such problems, the present inventors have found that the occurrence of voids due to heating of the sacrificial layer 2 is a low molecular weight among the resin components contained in the resin composition constituting the sacrificial layer 2. It has been found to be closely related to the content of food.

  And as a result of further studies, the present inventor has found that the generation of the voids can be effectively suppressed by setting the content of those having a molecular weight of less than 5,000 with respect to the entire resin component. . Specifically, in the resin component contained in the sacrificial layer 2, the above problem can be solved by setting the content of the resin component having a molecular weight of less than 5,000 to 4% or less in the resin component. As a result, the present invention has been completed.

  The content of the resin component having a molecular weight of less than 5,000 can be calculated by calculating an integral analysis value by GPC (gel permeation chromatogram) using THF as a solvent.

  In the resin component, the content of those having a molecular weight of less than 5,000 may be set to 4% or less, preferably 3.5% or less, more preferably 3% or less. Thereby, suppression of generation | occurrence | production of a void and heat resistance of the temporary fixing agent at the time of base-material processing can be made compatible.

  Further, in the resin component, the content of those having a molecular weight of more than 10,000 and less than 500,000 is preferably set to 70% or more, more preferably 75% or more, and further preferably 80% or more.

  As a result, the semiconductor wafer 3 is firmly fixed to the support base 1 via the sacrificial layer 2, and the semiconductor wafer 3 is accurately prevented or prevented from being separated or displaced during backside processing of the semiconductor wafer 3. can do.

(Desorption process)
Next, as shown in FIG. 1 (d), the sacrificial layer 2 is heated to thermally decompose the resin component to lower the molecular weight, so that the sacrificial layer 2 is melted or vaporized, and then the semiconductor wafer 3. Is detached from the support substrate 1 (fourth step).

  Although the temperature which heats the sacrificial layer 2 is suitably set according to the kind etc. of a resin component, it is preferable that it is about 100-500 degreeC, and it is more preferable that it is about 120-450 degreeC. As a result, the resin component can be surely thermally decomposed to have a low molecular weight, and alteration or deterioration of the semiconductor wafer 3 due to the semiconductor wafer 3 undergoing a thermal history can be suppressed or prevented accurately.

  In addition, when the sacrificial layer 2 is heated as described above, the content of the resin component having a molecular weight of more than 1,000 and less than 10,000 is preferably 25% or less, and 5 to 20 It is more preferable that it is about%. Thereby, the desorption / detachment of the semiconductor wafer 3 from the support base 1 in this step can be performed in a short time without causing the semiconductor wafer 3 to be damaged such as a crack.

  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. For example, a method of detaching the semiconductor wafer 3 by lifting it from the support substrate 1 may be used.

  In addition, when the sacrificial layer 2 is vaporized through the heating step, the sacrificial layer 2 is removed from between the semiconductor wafer 3 and the support base 1, so that the sacrificial layer 2 is removed from the support base 1. The semiconductor wafer 3 can be detached more easily.

(Washing process)
Next, in the desorption step, if the sacrificial layer 2 is in a molten state by heating the sacrificial layer 2 or if a part of the vaporized sacrificial layer 2 remains, as necessary. Thus, the sacrificial layer 2 remaining on the functional surface 31 of the semiconductor wafer 3 is cleaned.
That is, the residue of the sacrificial 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 sacrificial layer 2 is formed on the support substrate 1 in the sacrificial layer formation step. However, the present invention is not limited to this, and the sacrificial layer 2 is formed on both the support substrate 1 and the semiconductor wafer 3. Alternatively, the sacrificial layer 2 may be selectively formed on the semiconductor wafer 3 without forming the sacrificial layer 2 on the support substrate 1.
As described above, the back surface of the semiconductor wafer 3 is processed.

  In the case where the resin component contained in the sacrificial layer (resin composition) 2 is such that the melt viscosity or the vaporization temperature is lowered by irradiation with active energy rays, the sacrificial layer 2 is heated in the desorption step. Prior to this, the following active energy ray irradiation step may be performed.

(Active energy ray irradiation process)
In this step, the sacrificial layer 2 is irradiated with active energy rays.

  Here, when the resin component is one whose melt viscosity or vaporization temperature is lowered by irradiation with active energy rays, the resin composition melts or vaporizes in the presence of an acid or a base. A resin component that decreases in temperature and an activator that generates an acid or a base upon irradiation with an active energy ray on the temporary fixing agent are included. Therefore, when energy is imparted to the active agent contained in the temporary fixing agent (resin composition), active species such as acid or base are generated from the active agent. The melt viscosity or vaporization temperature decreases.

  Therefore, prior to the heating of the sacrificial layer 2, the sacrificial layer 2 is irradiated with the active energy rays, whereby the heating temperature, the heating time, etc. when heating the sacrificial layer 2 can be reduced or shortened. Therefore, this heating can be performed under more relaxed conditions. As a result, alteration / deterioration due to heating of the semiconductor wafer 3 can be suppressed or prevented more accurately.

  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.

Further, the irradiation amount of the active energy ray is not particularly limited, but is preferably ^{10mJ / cm 2 ~20000mJ / cm 2} , and more preferably ^{20mJ / cm 2 ~10000mJ / cm 2} .

  In this embodiment, the case where the semiconductor wafer 3 is used as the base material has been described as an example. However, the present invention is not limited to this, and for example, a wiring board, a circuit board, or the like can be used.

  As mentioned above, although the temporary fixing agent and the processing method of the base material of this invention were demonstrated based on embodiment of illustration, this invention is not limited to these.

For example, each constituent material contained in the temporary fixing agent can be replaced with an arbitrary material that can exhibit the same function, or an arbitrary material can be added.
Moreover, the arbitrary process may be added to the processing method of the base material of this invention as needed.

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

[Example 1A]
<Synthesis of 1,4-polybutylene carbonate>
1,4-butanediol (168.0 g, 1.864 mol) and diethyl carbonate (264.2 g, 2.236 mol) were added to a three-necked flask equipped with a stirrer, a raw material charging port, and a nitrogen gas inlet, and nitrogen was added. Heated at 90-100 ° C. under atmosphere to dissolve the mixture.

  Then, after adding a 20% sodium ethoxide ethanol solution (80 ml, 0.186 mol), the mixture was stirred at 90 to 100 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, the inside of the reaction vessel was depressurized by about 30 kPa, followed by 90 to 100 ° C. for 1 hour and 120 ° C. for 1 hour. Thereafter, the mixture was further stirred at 150 ° C. for 1 hour and at 180 ° C. for 2 hours under a vacuum of 0.1 kPa.

  The reaction product obtained above was dissolved in tetrahydrofuran (2 L), filtered, and the catalyst residue was removed. Thereafter, the filtrate was poured into a solution (20 L) of distilled water / methanol = 1/9, and the precipitate was recovered, further washed sufficiently with a solution (10 L) of distilled water / methanol = 1/9, and dried under reduced pressure. After that, 125 g of 1,4-polybutylene carbonate (yield 48%) was obtained.

  When the weight average molecular weight of the synthesized 1,4-polybutylene carbonate was measured by GPC, it was 35,000, the content of those having a molecular weight of less than 5,000 was 2.9%, and the molecular weight was The content of those exceeding 10,000 and less than 500,000 was 83.9%.

<Preparation of temporary fixative>
100 g of the obtained 1,4-polybutylene carbonate, Rhodolsil Photoinitiator 2074 (FABA) (Rhodia Japan Co., Ltd., Rhodorsil Photoinitiator 2074) as an activator, 1-chloro-4-propoxythioxanthone (manufactured by Lambson, UK) as a sensitizer 1.5 g of SPEEDCURE CPTX (trade name) was dissolved in 958.5 g of anisole (solvent) to prepare a temporary fixing agent having a resin concentration of 10%.

[Example 2A]
<Synthesis of isosorbide-type polycarbonate>
102.01 g (0.698 mol) of isosorbide, 149.53 g (0.698 mol) of diphenyl carbonate, and 0.0023 g (6.98 × 10 ⁻⁶ mol) of cesium carbonate were weighed, and then these were put into a reaction vessel. I put it in. As the first step of the reaction, the reaction vessel was immersed in a heating tank heated to 120 ° C. under a nitrogen atmosphere, stirred, the raw materials were dissolved, and stirring was continued for 2 hours. Next, as the second step of the reaction, the pressure inside the reaction vessel was reduced to 10 kPa, and stirring was continued at 120 ° C. for 1 hour. Next, as the third step of the reaction, the pressure inside the reaction vessel was reduced to 0.5 kPa or less, and stirring was continued at 120 ° C. for 1.5 hours. Next, as the fourth step of the reaction, the temperature of the heating tank is raised to 180 ° C. over about 30 minutes while reducing the pressure inside the reaction vessel to 0.5 kPa or less, and then stirred at 180 ° C. for 1.5 hours. Continued. The phenol produced in the second to fourth steps of the reaction was distilled out of the reaction vessel.

  After returning the pressure in the reaction vessel to normal pressure, 1.2 L of γ-butyrolactone was added to the reaction product obtained above to dissolve the product. Next, in a state where 12 L of a mixed solution of isopropanol / water = 9/1 (v / v) was stirred, a solution in which the product was dissolved was dropped. Next, the deposited precipitate was collected by suction filtration. The collected precipitate was washed with 4 L of a mixed solution of isopropanol / water = 9/1 (v / v), and then collected by suction filtration. The collected precipitate was dried with a vacuum dryer at 80 ° C. for 18 hours to obtain 123.15 g (yield 100%) of an isosorbide-type polycarbonate powder represented by the above chemical formula (2A).

  When the weight average molecular weight of the synthesized isosorbide-type polycarbonate was measured by GPC, it was 45,000, the content of those having a molecular weight of less than 5,000 was 2.2%, and the molecular weight was more than 10,000. The content of those less than 500,000 was 85.2%.

<Preparation of temporary fixative>
100.0 g of the obtained isosorbide polycarbonate 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 temporarily fixed with a resin component concentration of 33% by weight. An agent was prepared.

[Comparative Example 1A]
<Synthesis of 1,4-polybutylene carbonate>
1,4-butanediol (168.0 g, 1.864 mol) and diethyl carbonate (220.2 g, 1.864 mol) were added to a three-necked flask equipped with a stirrer, a raw material charging port, and a nitrogen gas inlet, and nitrogen was added. Heated at 90-100 ° C. under atmosphere to dissolve the mixture.

  Then, after adding a 20% sodium ethoxide ethanol solution (80 ml, 0.186 mol), the mixture was stirred at 90 to 100 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, the inside of the reaction vessel was depressurized by about 30 kPa, followed by 90 to 100 ° C. for 1 hour and 120 ° C. for 1 hour. Thereafter, the mixture was further stirred at 150 ° C. for 1 hour and at 180 ° C. for 2 hours under a vacuum of 0.1 kPa.

  The reaction product obtained above was dissolved in tetrahydrofuran (2 L), filtered, and the catalyst residue was removed. Thereafter, the filtrate was poured into a solution (20 L) of distilled water / methanol = 1/9, and the precipitate was recovered, further washed sufficiently with a solution (10 L) of distilled water / methanol = 1/9, and dried under reduced pressure. After that, 117 g of 1,4-polybutylene carbonate (45% yield) was obtained.

  When the weight average molecular weight of the synthesized 1,4-polybutylene carbonate was measured by GPC, it was 12,000, the content of those having a molecular weight of less than 5,000 was 16.0%, and the molecular weight was The content of more than 10,000 and less than 500,000 was 56.8%.

[Comparative Example 2A]
<Synthesis of isosorbide-type polycarbonate>
102.30 g (0.700 mol) of isosorbide, 155.95 g (0.728 mol) of diphenyl carbonate, and 0.0023 g (6.98 × 10 ⁻⁶ mol) of cesium carbonate were weighed, and then these were put into a reaction vessel. I put it in. As the first step of the reaction, the reaction vessel was immersed in a heating tank heated to 120 ° C. under a nitrogen atmosphere, stirred, the raw materials were dissolved, and stirring was continued for 2 hours. Next, as the second step of the reaction, the pressure inside the reaction vessel was reduced to 10 kPa, and stirring was continued at 120 ° C. for 1 hour. Next, as the third step of the reaction, the pressure inside the reaction vessel was reduced to 0.5 kPa or less, and stirring was continued at 120 ° C. for 1.5 hours. Next, as the fourth step of the reaction, the temperature of the heating tank is raised to 180 ° C. over about 30 minutes while reducing the pressure inside the reaction vessel to 0.5 kPa or less, and then stirred at 180 ° C. for 1.5 hours. Continued. The phenol produced in the second to fourth steps of the reaction was distilled out of the reaction vessel.

  After returning the pressure in the reaction vessel to normal pressure, 1.2 L of γ-butyrolactone was added to the reaction product obtained above to dissolve the product. Next, in a state where 12 L of a mixed solution of isopropanol / water = 9/1 (v / v) was stirred, a solution in which the product was dissolved was dropped. Next, the deposited precipitate was collected by suction filtration. The collected precipitate was washed with 4 L of a mixed solution of isopropanol / water = 9/1 (v / v), and then collected by suction filtration. The recovered precipitate was dried with a vacuum dryer at 80 ° C. for 18 hours to obtain 119.30 g (99% yield) of an isosorbide-type polycarbonate powder represented by the above chemical formula (2A).

  When the weight average molecular weight of the synthesized isosorbide-type polycarbonate was measured by GPC, it was 16,700, the content of those having a molecular weight of less than 5,000 was 14.8%, and more than 10,000, 500 The content of less than 6,000 was 66.2%.

<Preparation of temporary fixative>
100.0 g of isosorbide polycarbonate and 2.0 g of GSID26-1 (manufactured by Ciba Japan) as an activator (photoacid generator) are dissolved in 198.0 g of γ-butyrolactone to prepare a temporary fixing agent having a resin component concentration of 33% by weight. did.

[Example 1B]
<Synthesis of 5-decylnorbornene polymer>
Into a sufficiently dried reaction vessel, 430 g of ethyl acetate, 890 g of cyclohexane, and 223 g of 5-decylnorbornene (0.95 mol) were introduced. Dry nitrogen was passed through the system at 40 ° C. for 30 minutes to remove dissolved oxygen. Thereafter, 1.33 g (2.75 × 10 ⁻⁴ mol) of bis (toluene) bis (perfluorophenyl) nickel dissolved in 12 g of ethyl acetate was added to the reaction system. The above system was heated from 40 ° C. to 55 ° C. over 15 minutes, and the system was stirred for 3 hours while maintaining the temperature.

  A solution obtained by dissolving 26 g of glacial acetic acid in about 1500 g of pure water to which 49 g of 30% hydrogen peroxide water was added was added to the obtained solution, and the mixture was stirred at 50 ° C. for 5 hours. Removed.

  The remaining organic layer was washed by adding, stirring, and removing a mixture of 220 g of methanol and 200 g of isopropyl alcohol. Further, after adding 510 g of cyclohexane and 290 g of ethyl acetate to the washed organic layer and uniformly dissolving the system, a mixture of 156 g of methanol and 167 g of isopropyl alcohol was washed by adding to stirring to removing (2 Repeated times).

  180 ml of cyclohexane was added to the washed organic layer to dissolve the system uniformly, and 670 g of trimethylbenzene was further added. Then, 543 g (35% mesitylene solution) of 5-decylnorbornene polymer was obtained by evaporating and removing cyclohexane with a rotary evaporator under reduced pressure.

  When the weight average molecular weight of the synthesized 5-decylnorbornene polymer was measured by GPC, it was 75,200, and the content of those having a weight average molecular weight of less than 5,000 was 1.2%. The content of those having an average molecular weight of more than 10,000 and less than 500,000 was 90.6%.

<Preparation of temporary fixative>
300 g of a 35% mesitylene solution of the obtained 5-decylnorbornene polymer was diluted with 50 g of mesitylene (solvent) to prepare a temporary fixing agent having a resin concentration of 30%.

[Comparative Example 1B]
<Synthesis of 5-decylnorbornene polymer>
Into a sufficiently dried reaction vessel, 430 g of ethyl acetate, 890 g of cyclohexane, and 223 g of 5-decylnorbornene (0.95 mol) were introduced. Dry nitrogen was passed through the system at 40 ° C. for 30 minutes to remove dissolved oxygen. Thereafter, 2.66 g (5.50 × 10 ⁻⁴ mol) of bis (toluene) bis (perfluorophenyl) nickel dissolved in 12 g of ethyl acetate was added to the reaction system. The above system was heated from 40 ° C. to 55 ° C. over 15 minutes, and the system was stirred for 3 hours while maintaining the temperature.

  A solution obtained by dissolving 26 g of glacial acetic acid in about 1500 g of pure water to which 49 g of 30% hydrogen peroxide water was added was added to the obtained solution, and the mixture was stirred at 50 ° C. for 5 hours. Removed.

  The remaining organic layer was washed by adding, stirring, and removing a mixture of 220 g of methanol and 200 g of isopropyl alcohol. Further, after adding 510 g of cyclohexane and 290 g of ethyl acetate to the washed organic layer and uniformly dissolving the system, a mixture of 156 g of methanol and 167 g of isopropyl alcohol was washed by adding to stirring to removing (2 Repeated times).

  180 ml of cyclohexane was added to the washed organic layer to dissolve the system uniformly, and 670 g of trimethylbenzene was further added. Then, 540 g of a 5-decylnorbornene polymer (35% mesitylene solution) was obtained by evaporating and removing cyclohexane with a rotary evaporator under reduced pressure.

  When the weight average molecular weight of the synthesized 5-decylnorbornene polymer was measured by GPC, it was 30,200, and the content of those having a weight average molecular weight of less than 5,000 was 4.2%. The content of those having an average molecular weight of more than 10,000 and less than 500,000 was 77.8%.

<Preparation of temporary fixative>
300 g of a 35% mesitylene solution of the obtained 5-decylnorbornene polymer was diluted with 50 g of mesitylene (solvent) to prepare a temporary fixing agent having a resin concentration of 30%.

2. Next, the back surface of the semiconductor wafer was processed using the temporary fixing agent of each example and each comparative example.

<1> First, using a spin coater, the temporary fixing agent of each example and each comparative example was applied to 8-inch transparent glass (rotation speed: 1,200 rpm, time: 30 seconds), and then on a hot plate. Pre-baking was performed at 120 ° C. for 5 minutes to form a thin film made of a temporary fixing agent having a thickness of 5 μm.

<2> Next, using a substrate bonder (model number SB-8e, manufactured by SUSS Microtec Co., Ltd.), an 8-inch silicon wafer (725 μm thickness) is temporarily attached to an 8-inch transparent glass through a thin film made of a temporary fixing agent. Fixed (atmosphere: 10 ⁻² mbar, temperature: 160 ° C., load: 10 kN, time: 1 minute).

<3> Next, with respect to the silicon wafer temporarily fixed to the transparent glass, the lower surface (back surface) of the semiconductor wafer is ground using a grinding device (“DFG8540” manufactured by DISCO), and the thickness of the semiconductor wafer is determined. It processed so that it might be set to 50 micrometers.

<4> Next, a sample in which an 8-inch silicon wafer was temporarily fixed on an 8-inch transparent glass was put into an oven, heat treatment was performed at a predetermined temperature and time, and the temporary fixing agent was thermally decomposed.

For the temporary fixing agents of Examples 1A to 2A and Comparative Examples 1A to 2A, irradiation with ultraviolet rays (active energy rays) having a wavelength of 365 nm at a wavelength of 2,000 mJ / cm ² prior to the heat treatment, The temperature at which the fixative thermally decomposes was lowered.

  Moreover, the temporary fixing agent of Examples 1A-2A and Comparative Examples 1A-2A was thermally decomposed by a heat treatment at 320 ° C. for 30 minutes. Furthermore, the temporary fixing agents of Example 1B and Comparative Example 1B were thermally decomposed by heat treatment at 450 ° C. for 120 minutes.

<5> Next, the pyrolyzed sample was taken out of the oven, tweezers were put in the gap between the 8-inch transparent glass and the 8-inch silicon wafer, and the 8-inch silicon wafer was detached.

3. Evaluation 3-1. Measurement of Wafer Thickness 10 points at intervals of 20 mm from the outer periphery of the 8-inch silicon wafer obtained in <5> above to the outer periphery of the diagonal line, and 10 points at intervals of 20 mm on the orthogonal outer periphery straight line. The thickness of 20 silicon wafers was measured with a non-contact film thickness meter, and judged according to the following criteria.

○: Variation of 20 measurement points is less than 5 μm ×: Variation of 20 measurement points is 5 μm or more

3-2. Confirmation of the presence or absence of voids After the step <3> above, the voids of the temporary fixing agent were visually observed from the transparent glass side, and judged according to the following criteria.

○: No void occurred △: Partial void generated ×: Void generated on the entire surface

3-3. Detachment of silicon wafer The 8-inch silicon wafer was removed with the tweezers in <5> above so that the silicon wafer was not cracked, and the time until the silicon wafer was completely detached from the transparent glass was measured. According to the time, the determination was made according to the following criteria.

○: Time until desorption is less than 10 minutes ×: Time until desorption is 10 minutes or more

  Table 1 shows the evaluation results of Examples 1A, 2A, Example 1B and Comparative Examples 1A, 2A, and Comparative Example 1B.

  As shown in Table 1, in each example, grinding of the lower surface of the silicon wafer with the thickness of the resin component before heating and the molecular weight of the resin component before heating is set within an appropriate range. In addition to being able to be performed without variation, the silicon wafer could be detached without causing cracks in a short time.

  On the other hand, in each comparative example, since the molecular weight of the resin component before heating and before heating was not set within an appropriate range, voids were generated, and as a result, the lower surface of the semiconductor wafer was ground. In this case, the thickness varies, and it takes a long time to remove the silicon wafer without cracking.

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

Claims (10)

Temporary fixing agent used for temporarily fixing the base material to a supporting base material in order to process the base material, and for releasing the base material from the supporting base material by heating after processing the base material. There,
In the temporary fixing agent before heating, the resin component contained in the temporary fixing agent has a molecular weight of less than 5,000, and the content of the resin component is 4% or less in the resin component. Fixative.   2. The temporary fixing agent according to claim 1, wherein in the temporary fixing agent before heating, the resin component has a molecular weight of more than 10,000 and less than 500,000 in the resin component. Fixative.   The temporary fixing agent according to claim 1 or 2, wherein the resin component is melted or vaporized by thermal decomposition and low molecular weight by the heating of the temporary fixing agent.   In the temporary fixing agent after the resin component is thermally decomposed and reduced in molecular weight, the resin component has a molecular weight of more than 1,000 and less than 10,000 in the resin component with a content of 25%. The temporary fixing agent according to claim 3, wherein:   The temporary fixing agent according to claim 3 or 4, wherein the resin component has a melt viscosity or a temperature at which the vaporization temperature is lowered by irradiation of the temporary fixing agent with active energy rays.   The resin component has a lower melt viscosity or vaporization temperature in the presence of an acid or base, and the temporary fixing agent has an activity of generating an acid or a base by irradiation with the resin component and the active energy ray. The temporary fixing agent according to claim 5, comprising a resin composition containing an agent.   The temporary fixing agent according to claim 5 or 6, wherein the resin component is a polycarbonate-based resin.   The temporary fixing agent according to claim 3 or 4, wherein the resin component does not decrease in melt viscosity or vaporizing temperature by irradiation of the temporary fixing agent with active energy rays.   The temporary fixing agent according to claim 8, wherein the resin component is a norbornene-based resin. A first step of forming a thin film composed of the temporary fixing agent according to any one of claims 1 to 9 on at least one of the substrate and the support substrate;
A second step of bonding the substrate and the support substrate through the thin film;
A third step of processing the surface of the substrate opposite to the supporting substrate;
And a fourth step of desorbing the base material from the support base material by heating and thinning the thin film.

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