U.S. patent application number 13/570306 was filed with the patent office on 2012-11-29 for energy ray-curable polymer, an energy ray-curable adhesive composition, an adhesive sheet and a processing method of a semiconductor wafer.
This patent application is currently assigned to LINTEC Corporation. Invention is credited to Jun Maeda, Keiko Tanaka.
Application Number | 20120302041 13/570306 |
Document ID | / |
Family ID | 41135264 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120302041 |
Kind Code |
A1 |
Maeda; Jun ; et al. |
November 29, 2012 |
Energy Ray-Curable Polymer, an Energy Ray-Curable Adhesive
Composition, an Adhesive Sheet and a Processing Method of a
Semiconductor Wafer
Abstract
In a pressure-sensitive adhesive composition or a
pressure-sensitive adhesive sheet containing an energy ray-curable
polymer, problems associated with the volatilization of a low
molecular weight compound contained in the composition are
overcome. An energy ray-curable polymer characterized by comprising
a radical generating group, which is capable of initiating a
polymerization reaction upon excitation with an energy ray, and an
energy ray-polymerizable group bonded together in the main or side
chain.
Inventors: |
Maeda; Jun; (Munich, DE)
; Tanaka; Keiko; (Gunma, JP) |
Assignee: |
LINTEC Corporation
Tokyo
JP
|
Family ID: |
41135264 |
Appl. No.: |
13/570306 |
Filed: |
August 9, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12935677 |
Dec 6, 2010 |
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PCT/JP2009/054742 |
Mar 12, 2009 |
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13570306 |
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Current U.S.
Class: |
438/464 ;
257/E21.238; 428/355AC; 524/555 |
Current CPC
Class: |
C08F 220/14 20130101;
Y10T 428/2852 20150115; Y10T 428/2891 20150115; H01L 2221/68327
20130101; H01L 2221/6834 20130101; H01L 21/6836 20130101; C09J
2301/416 20200801; C08F 220/30 20130101; C08F 220/26 20130101; C08F
220/18 20130101; H01L 21/6835 20130101; C09J 7/20 20180101; C09J
2203/326 20130101 |
Class at
Publication: |
438/464 ;
428/355.AC; 524/555; 257/E21.238 |
International
Class: |
H01L 21/304 20060101
H01L021/304; C09J 139/00 20060101 C09J139/00; C09J 7/02 20060101
C09J007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2008 |
JP |
2008-093897 |
Claims
1. An energy ray-curable acrylic polymer having a radical
generating group capable of initiating polymerization reaction
under the excitation by an energy ray, and an energy
ray-polymerizable group bonded to a main chain or a side chain of
the polymer.
2. The energy ray-curable acrylic polymer as set forth in claim 1
wherein said radical generating group includes a phenyl carbonyl
group which may comprise a substituent group in an aromatic
ring.
3. The energy ray-curable acrylic polymer as set forth in claim 2
wherein said radical generating group is derived from a monomer
obtained by adding a compound comprising a polymerizable double
bond to a hydroxyl group of a photo polymerization initiator
comprising hydroxyl group.
4. The energy ray-curable acrylic polymer as set forth claim 3
having a weight average molecular weight of 300,000 to
1,600,000.
5. An energy ray-curable adhesive composition comprising the energy
ray-curable acrylic polymer as set forth in claim 4.
6. An adhesive sheet comprising a substrate and an energy
ray-curable adhesive layer formed thereon, and said energy
ray-curable adhesive layer comprising the energy ray-curable
adhesive composition as set forth in claim 5.
7. The adhesive sheet as set forth in claim 6 used for a
semiconductor wafer processing.
8. A processing method of a semiconductor wafer comprising the step
of adhering the energy ray-curable adhesive layer of the adhesive
sheet as set forth in claim 7 to a circuit surface of the
semiconductor wafer formed with the circuit on the front surface,
and performing the backside processing of the wafer.
9. The processing method of the semiconductor wafer as set forth in
claim 8 wherein said backside processing of the semiconductor wafer
is the backside grinding.
10. The processing method of the semiconductor wafer comprising the
step of adhering the energy ray-curable adhesive layer of the
adhesive sheet as set forth in claim 7 to the backside of the
semiconductor wafer formed with the circuit on the front surface,
and performing dicing of the wafer.
11. The processing method of the semiconductor wafer as set forth
in claim 10 further comprising the step involving a heat
application or a heat generation.
12. An energy ray-curable adhesive composition comprising: an
energy ray-curable polymer having a radical generating group
capable of initiating polymerization reaction under the excitation
by an energy ray, and an energy ray-polymerizable group bonded to a
main chain or a side chain of the polymer.
13. The energy ray-curable adhesive composition as set forth in
claim 12 wherein said radical generating group includes a phenyl
carbonyl group which may comprise a substituent group in an
aromatic ring.
14. The energy ray-curable adhesive composition as set forth in
claim 13 wherein said radical generating group is derived from a
monomer obtained by adding a compound comprising a polymerizable
double bond to a hydroxyl group of a photo polymerization initiator
comprising hydroxyl group.
15. The energy ray-curable adhesive composition as set forth in
claim 14 having a weight average molecular weight of 300,000 to
1,600,000.
16. An adhesive sheet comprising a substrate and an energy
ray-curable adhesive layer formed thereon comprising the energy
ray-curable adhesive composition as set forth in claim 12, wherein
an adhesive force against a mirror surface of the semiconductor
wafer is 2000 to 1500 mN/25 mm before the energy ray irradiation
and after the energy ray irradiation the adhesive force is 1 to 50%
of that before the irradiation.
17. The adhesive sheet as set forth in claim 16 used for a
semiconductor wafer processing.
18. A processing method of a semiconductor wafer comprising the
step of adhering the energy ray-curable adhesive layer of the
adhesive sheet as set forth in claim 17 to a circuit surface of the
semiconductor wafer formed with the circuit on the front surface,
and performing the backside processing of the wafer.
19. The processing method of the semiconductor wafer as set forth
in claim 18 wherein said backside processing of the semiconductor
wafer is the backside grinding.
20. The processing method of the semiconductor wafer comprising the
step of adhering the energy ray-curable adhesive layer of the
adhesive sheet as set forth in claim 17 to the backside of the
semiconductor wafer formed with the circuit on the front surface,
and performing dicing of the wafer.
21. The processing method of the semiconductor wafer as set forth
in claim 20 further comprising the step involving a heat
application or a heat generation.
Description
[0001] This application is a Continuation Application of U.S. Ser.
No. 12/935,677, filed on Dec. 6, 2010, which is a U.S. national
stage application of PCT/JP2009/054742 filed on Mar. 12, 2009,
which claims priority of Japanese patent document 2008-093897 filed
on Mar. 31, 2008 in Japan, the entireties of which are incorporated
herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to an energy ray-curable
polymer, an adhesive composition and the adhesive sheet using
thereof. Also, the present invention relates to the processing
method of the semiconductor wafer, and in particular the present
invention relates to a backside processing of the semiconductor
wafer and the dicing processing of the semiconductor wafer.
BACKGROUND OF THE INVENTION
[0003] After a circuit is formed on the surface of the
semiconductor wafer, a grinding processing is performed to the
backside of the wafer, the backside grinding step which controls
the thickness of the wafer and the dicing step which separate the
wafer into predetermined chip size are carried out. Also, followed
by the backside grinding step, the processing treatment which
involves a heat generation such as an etching treatment is further
performed to the backside.
[0004] During the etching of the backside grinding, the adhesive
sheet so called backgrind tape is stuck to the circuit surface of
the wafer in order to protect the circuit. Also, during the dicing
of the wafer, the adhesive sheet so called a dicing tape is stuck
to the backside of the wafer in order to prevent the scattering of
the chips which are formed by dicing (hereinafter, such adhesive
sheet in total may be described as "a semiconductor wafer
processing adhesive sheet" or "a wafer processing adhesive
sheet".
[0005] As for these wafer processing adhesive sheet, in particular
as for the backgrind tape, it is required, [0006] to prevent the
damage to the circuit and the wafer body, [0007] to have no residue
of the adhesive agent (glue residue) of the adhesive agent on the
circuit after the releasing, [0008] to prevent the penetration of
the grinding water to the circuit surface which washes out the
grinding debris generated during the backside grinding and removes
the heat generated during the grinding, and [0009] to sufficiently
maintain the precision of the wafer thickness after the
grinding.
[0010] Further, when performing the processing treatment involving
a generation of the heat or a heat application to the backside, it
is required that the volatile component is not generated from the
adhesive layer.
[0011] Also, as for the dicing tape, it is required, [0012] to hold
the wafer with a sufficient adhesive force during the dicing,
[0013] to release the chip easily from the dicing tape during the
pickup of the chip, [0014] to have no reside of the adhesice agent
on the backside of the chip which is picked up, and [0015] that the
low molecular weight composition which is included in the adhesive
layer does not flow out due to the dicing water during the
dicing.
[0016] As for such wafer processing adhesive sheet, the adhesive
sheet is widely used which is provided with the energy ray-curable
adhesive layer, which cures by the energy ray such as ultraviolet
ray, on the substrate consisting of the resin film. According to
the adhesive sheet of the energy ray-curable type, during the
backside grinding or dicing of the wafer, the wafer is held by
strong adhesive force; therefore the grinding water is prevented
from penetrating into the circuit surface and the chip is prevented
from scattering. Also, after finishing the backside grinding or the
dicing, the adhesive force is reduced since the adhesive layer
cures by irradiating the energy ray thereto, hence the wafer (chip)
is released from the adhesive sheet without the glue residue.
[0017] As for the energy ray-curable adhesive agent, the adhesive
agent formed by blending the energy ray-curable resin having
relatively low molecular weight and the photo polymerization
initiator to the acrylic adhesive polymer, is well known. However,
as for such adhesive agent, because it includes the low molecular
weight substances each component is not necessarily mixed
uniformly, and when the energy ray curing is carried out, an
insufficient curing of the adhesive agent occurred in some cases,
or the low molecular weight substances remained unreacted in some
cases. Therefore, the adhesive agent remained on the wafer (chip)
in some cases, or the wafer (chip) was contaminated by the low
molecular weight substances in some cases.
[0018] In order to resolve such problems, the wafer processing
adhesive sheet is proposed which comprises the energy ray-curable
adhesive layer comprising the photo polymerization initiator and
the energy ray-polymerizable adhesive polymer (hereinafter, it may
be described as "polymerizable group adduct type adhesive agent")
introducing the energy ray-polymerizable group in the molecule of
the adhesive polymer by reacting the acrylic adhesive polymer to
the compound including the energy ray-polymerizable group (Patent
document 1). According to such polymerizable adduct type adhesive
agent, the polymerizalbe group is uniformly dispersed in the
adhesive layer, and the contamination due to the insufficient
curing or the low molecular weight substances is reduced since the
low molecular weight substances low.
[0019] Similarly, the polymer is proposed which binds the group
forming the free radical which initiates the polymerization
reaction under the excitation by the energy ray to the adhesive
polymer (Patent document 2), or the polymer binding the photo
polymerization initiator to the adhesive polymer is proposed
(Patent document 3) in order to prevent the insufficient curing of
the adhesive agent after the energy ray irradiation (hereinafter,
these may be described as "radical generating group adduct type
adhesive agent"). These radical generating group adduct type
adhesive agent does not have polymerizing property by itself,
therefore it is used together with the energy ray-curable resin
having relatively low molecular weight substances as described in
the above. [0020] Patent document 1: JP-A-H09-298173 [0021] Patent
document 2: JP-A-H08-333555 [0022] Patent document 3:
JP-A-H09-111200
DISCLOSURE OF THE INVENTION
Technical Problems to be Solved by the Invention
[0023] As for the energy ray-curable adhesive agent using the
polymerizable group adduct type adhesive agent described in the
above, the photo polymerization initiator is blended together with
the polymerizable group adduct type adhesive agent. Also, the
radical generating group adduct type adhesive agent of the patent
document 2 and 3 is used together with the energy ray-curable
resin. Both the photo polymerization initiator and the energy
ray-curable resin are compounds having relatively low molecular
weight.
[0024] The energy ray-curable adhesive layer is obtained by
diluting the above mentioned solvent followed by applying to the
substrate or the release film then drying. However, in case the low
molecular weight compound is included in the energy ray-curable
adhesive agent, the low molecular weight compound volatilizes
during the drying; hence the adhesive agent having the composition
as designed couldn't be obtained in some cases.
[0025] For example, when using the photo polymerization initiator
having low molecular weight, the photo polymerization initiator is
volatilizing during the drying. If this happens excessively, then
curing of the adhesive agent by the energy ray irradiation becomes
insufficient; thereby there are problems that it causes the
adhesive force after the curing to rise and also causes the glue
residue against the adherend.
[0026] Also, when performing the wafer processing by using the
wafer processing adhesive sheet, in case of performing the heat
treatment to the semiconductor wafer or in case of carrying out the
processing involving the heat application or heat generation as dry
etching, the processing may be carried out under reduced pressure
or in vacuo. Here, the low molecular weight compound remained in
the adhesive layer after the curing volatilizes and causes similar
problem as mentioned in above or it may contaminate the
semiconductor apparatus due to the volatile gas component
generated.
[0027] Furthermore, when using for the wafer processing, the water
is sprayed in order to remove the heat and the cutting debris
generated during the wafer backside grinding or the dicing. Here,
the low molecular weight compound included in the adhesive layer
may flow out.
[0028] Therefore, in regards with the energy ray-curable adhesive
composition used in the wafer processing adhesive sheet, the
present invention aims to solve the various problems accompanied
with volatilization of the low molecular weight compound included
in the composition.
Means for Solving the Problems
[0029] The objectives of the present invention aiming to solve such
problems are as follows.
[0030] (1) An energy ray-curable polymer having a radical
generating group capable of initiating polymerization reaction
under the excitation by an energy ray, and an energy
ray-polymerizable group bonded to a main chain or a side chain of
the polymer.
[0031] (2) The energy ray-curable polymer as set forth in (1)
wherein said radical generating group includes a phenyl carbonyl
group which may comprise a substituent group in an aromatic
ring.
[0032] (3) The energy ray-curable polymer as set forth in (1) or
(2) wherein said radical generating group is derived from a monomer
obtained by adding a compound comprising a polymerizable double
bond to a hydroxyl group of a photo polymerization initiator
comprising hydroxyl group.
[0033] (4) The energy ray-curable polymer as set forth in any one
of (1) to (3) having a weight average molecular weight of 300,000
to 1,600,000.
[0034] (5) An energy ray-curable adhesive composition comprising
the energy ray-curable polymer as set forth in any one of (1) to
(4).
[0035] (6) An adhesive sheet comprising a substrate and an energy
ray-curable adhesive layer formed thereon, and said energy
ray-curable adhesive layer comprising the energy ray-curable
adhesive composition as set forth in (5).
[0036] (7) The adhesive sheet as set forth in (6) used for a
semiconductor wafer processing.
[0037] (8) A processing method of a semiconductor wafer comprising
the step of adhering the energy ray-curable adhesive layer of the
adhesive sheet as set forth in (7) to a circuit surface of the
semiconductor wafer formed with the circuit on the front surface,
and performing the backside processing of the wafer.
[0038] (9) The processing method of the semiconductor wafer as set
forth in (8) wherein said backside processing of the semiconductor
wafer is the backside grinding.
[0039] (10) The processing method of the semiconductor wafer
comprising the step of adhering the energy ray-curable adhesive
layer of the adhesive sheet as set forth in (7) to the backside of
the semiconductor wafer formed with the circuit on the front
surface, and performing the dicing of the wafer.
[0040] (11) The processing method of the semiconductor wafer as set
forth in any one of (8) to (10) further comprising the step of
applying or generating a heat.
Effect of the Invention
[0041] According to the present invention, in the adhesive sheet,
the low molecular weight compound amount included in the adhesive
agent before and after the curing by the energy ray is
significantly reduced, hence the various problems such as the
compositional changes along with the volatilization of the low
molecular weight compound and the generation of the volatile gas or
so can be solved. Furthermore, when using as for the semiconductor
wafer processing, though the water is sprayed in order to remove
the heat and the debris generated during the backside grinding and
the dicing of the wafer, there is no composition change of the
adhesive layer due to the flow out of the low molecular weight
compound, since the amount of the low molecular weight compound
included in the adhesive agent is significantly lowered.
BEST MODE FOR CARRYING OUT THE INVENTION
[0042] Hereinafter, the preferable embodiment of the present
invention will be described in detail including the embodiment of
the best mode.
[0043] The energy ray-curable polymer (A) of the present invention
is the energy ray-curable polymer having the radical generation
group capable of initiating the polymerization reaction under the
excitation of the energy ray and the energy ray polymerization
group bonded to the main chain or the side chain. As for the
preferable embodiment, it is obtained by reacting the radical
generating group containing polymer (a1) comprising the radical
generating group containing monomer unit, the functional group
containing monomer unit and other monomers depending on the needs,
and the energy ray-polymerizing group containing compound (a2)
comprising the substituent group reacting with said functional
group.
[The Radical Generating Group containing Monomer]
[0044] The radical generating group containing monomer used in the
present invention becomes the monomer which derives the radical
generating group of the energy ray-curable polymer of the present
invention. Said monomer comprises the polymerizable double bond,
and the group generating the free radical group (radical) which
initiates the polymerization reaction under the excitation by the
energy ray. As for the radical generating group, for example, the
group including the phenyl carbonyl group which may comprise the
substituent group in the aromatic ring; as shown in the following
general formula.
##STR00001##
[0045] (R1 may be hydrogen atom or a carbohydrate group having
carbon atoms of 1 to 12, and ether bond and hydroxyl group my be
present with in R1)
[0046] Such radical generating group containing monomer is for
example obtained by the addition reaction of the compound
comprising the radical generating group and the compound comprising
the polymerizable double bond.
[0047] As for the compound comprising the radical generating group,
for example, photo polymerization initiator comprising the hydroxyl
group may be mentioned. Specifically,
##STR00002##
may be mentioned.
[0048] The monomer obtained by the addition reaction of such
compound comprising the radical generating group and the compound
comprising the polymerizable double bond, is preferable as the
radical generating group containing monomer.
[0049] As for the compound comprising the polymerizable double
bond, the compound comprising the polymerizble double bond having
the functional group which react with the hydroxyl group is
preferable; and for example, methacryloyloxyethyl isocyanate,
meth-isopropenyl-.alpha.,.alpha.-dimethylbenzyl isocyanate,
methacryloyl isocyanate, allyl isocyanate; glycidyl(meth)acrylate
and; (meth)acrylic acid may be mentioned. Also, acryloyl
monoisocyanate compound obtained by reacting a diisocyanate or
polyisocyanate compound with hydroxyethyl(meth)acrylate; and
acryloyl monoisocyanate compound obtained by reaction of
diisocyanate or polyisocyanate compound, a polyol compounds and
hydroxyethyl(meth)acrylate may be mentioned.
[0050] By reacting said compound comprising the hydroxyl group and
the radical generating group, with said compound comprising the
polymerizable double bond (for example, methacryloyloxyethyl
isocyanate); the hydroxyl group of the compound comprising the
radical generating group and the functional group (for example,
isocyanate group) of the compound comprising the polymerizable
double bond reacts; thereby the radical generating group containing
monomer having the polymerizable double bond can be obtained.
[0051] As for the specific example of other monomers,
o-acryloylbenzophenone, p-acryloylbenzophenone,
o-methacryloylbenzophenone, p-methacryloylbenzophenone,
p-(meth)acryloylethoxybenzophenone, monohydroxyalkylacrylate having
2 to 12 methylene groups derived from the benzophenone carbonic
acid shown in the following general formula, or bezophenone
carbonate ester of the monohydroxymethacrylate.
##STR00003##
(R.sub.1 and R.sub.2 may be hydrogen atom or alkyl group having 1
to 4 of carbon atoms respectively, R.sub.3 may be hydrogen or a
methyl group and m is an integer from 2 to 12), and compound in the
following general formula,
##STR00004##
(R.sub.1 and R.sub.2 may be hydrogen atom or alkyl group having 1
to 4 of carbon atoms respectively, and R.sub.3 and R.sub.4 includes
hydrogen or methyl group respectively.) may be mentioned. (The
Radical Generating Group containing Polymer(a1))
[0052] The radical generating group containing polymer (a1) is
formed by polymerizing the radical generating group containing
monomer, the functional group containing monomer for introducing
the energy ray-polymerizable group, and other monomers if
needed.
(The Functional Group containing Monomer)
[0053] The functional group containing monomer constituting the
radical generating group containing polymer (a1) is a monomer for
introducing the energy ray-polymerizable group to the energy
ray-curable polymer of the present invention. It is a monomer
comprising the polymerizable double bond, and the functional group,
such as the hydroxyl group, the carboxyl group, the amino group,
the substituted amino group, the epoxy group or so in the molecule,
and preferably an unsaturated compound containing the hydroxyl
group or an unsaturated compound containing the carboxyl group are
used.
[0054] As specific examples of such functional group containing
monomer, an acrylate containing hydroxyl group such as
2-hydroxyehtyl acrylate, 2-hydroxyethyl methacrylate,
2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate,
2-hydroxybutyl acrylate and 2-hydroxybutyl methacrylate; and
compounds containing carboxyl group such as acrylic acid,
methacrylic acid, and itaconic acid or so, may be mentioned. The
above mentioned functional group containing monomer may be used
alone or in combination of two or more thereof.
[Other Monomers]
[0055] Other monomers constituting the radical generating group
containing polymer (a1) are not particularly limited, however, for
example, as the polymer, an acrylic copolymer mainly using the
acrylic monomer, and the olefin copolymer mainly using the olefin
monomer may be mentioned. If the energy ray-curable polymer of the
present invention is used as the adhesive agent, various acrylic
copolymer which is relatively easy to control the adhesive force is
preferable, and various acrylic monomer is used as the constitution
unit.
[0056] As for the acrylic monomer, an (meth)acrylic acid alkyl
ester having 1 to 18 carbon atoms of alkyl group is used. As the
derivative of (meth)acrylic acid alkyl ester, methyl acrylate,
metyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl
acrylate, propyl methacrylate, isopropyl acrylate, isopropyl
methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl
acrylate, isobutyl methacrylate, n-hexyl methacrylate, 2-ethyl
hexyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl acrylate,
lauryl methacrylate, dimethyl acrylamide or so may be
mentioned.
[0057] Furthermore, a vinyl monomer copolymerizable with the above
mentioned ester monomer may be copolymerized. As for the
copolymerizable vinyl monomer, styrene, .alpha.-methyl styrene,
vinyl toluene, vinyl formate, vinyl acetate, acrylonitrile,
glycidyl acrylate, glycidyl methacrylate or so may be
mentioned.
(The Formation of the Radical Generating Group containing Polymer
(a1))
[0058] The radical generating group containing polymer (a1) is
formed by polymerizing the above mentioned radical generating group
containing monomer, the functional group containing monomer, and
other monomers if need.
[0059] The radical generating group containing polymer (a1)
contains the structural units derived from the above radical
generating group containing monomer usually in an ratio of 0.1 to
30 weight %, preferably 0.5 to 10 weight %, and more preferably 1
to 5 weight %. The radical generating group containing polymer (a1)
contains the structural units derived from the above functional
group containing monomer usually in an ratio of 1 to 70 weight %,
preferably 5 to 40 weight %, and more preferably 10 to 30 weight %.
The radical generating group containing polymer (a1) contains the
structural units derived from above other monomers usually in an
ratio of 0 to 99 weight %, preferably 35 to 90 weight %, and more
preferably 50 to 80 weight %.
[0060] The radical generating group containing polymer (a1) is
obtained by copolymerizing the above mentioned radical generating
group containing monomer, the functional group containing monomer,
and other monomers by a usual method; however, the production
method of the radical generating group containing polymer (a1) is
not particularly limited, and for example, it may be produced by
using the solution polymerization under the presence of the
solvent, the chain transfer agent, and the polymerization initiator
or so; or by the aqueous emulsion polymerization under the presence
of the emulsifier, the chain transfer agent, the polymerization
initiator, and the dispersing agent, or so.
[0061] Note that, the monomer concentration during the
polymerization is usually 30 to 70 weight %, preferably 40 to 60
weight % or so. As for the polymerization initiator used for the
polymerization, a persulfate such as potassium persulfate, ammonium
persulfate or so, an azo compound such as
2,2-`azobisisobutylonitrile, 2,2'-azobis(2,4-dimethylvaleronitrile)
or so, called an peroxide such as hydrogen peroxide, benzoyl
peroxide, lauryl peroxide or so, and a redox polymerization
initiator comprising the combination of ammonium persulfate, with
sodium sulfite or acid sodium sulfite or so may be mentioned. The
amount of the polymerization initiator mentioned in the above is
controlled within the range of 0.2 to 2 weight %, and preferably
within the range of 0.3 to 1 weight % with respect to the whole
amount of the monomer used in the polymerization.
[0062] Further, as for the chain transfer agent added during the
copolymerization; alkyl mercaptans such as octyl mercaptan, nonyl
mercaptan, decyl mercaptan, dodecyl mercaptan or so; thioglycolates
such as octyl thioglycolate, nonyl thioglycolate, 2-ethyl hexyl
thioglycolate, 2-ethyl hexyl .beta.-mercaptopropionate or so;
2,4-diphenyl-4-methyl-1-pentene,
1-methyl-4-isopropylidine-1-cyclohexene or so may be mentioned.
Particularly, when using the thioglycolates,
2,4-diphenyl-4-methyl-1-pentene, and
1-methyl-4-isopropylidine-1-cyclohexene, it is preferable since the
obtained copolymer has low odor. Note that, the amount of chain
transfer agent is controlled within the range of 0.001 to 3 weight
% or so with respect to the whole monomer to be polymerized. Also,
usually, the polymerization reaction is performed under 60 to
100.degree. C. for 2 to 8 hours. Further, a viscosity improver, a
wetting agent, a leveling agent, and an anti-foaming agent may be
added accordingly.
[The Energy Ray-Curable Polymer (A)]
[0063] The energy ray-curable polymer (A) of the present invention
is obtained by reacting the functional group derived from the
functional group containing monomer of above mentioned radical
generating group containing polymer (a1) with the energy
ray-polymerizable group containing compound (a2).
[The Energy Ray-Polymerizable Group containing Compound (a2)]
[0064] The energy ray-polymerizable group containing compound (a2)
includes, the substituent group which can react with the functional
group. This substituent group varies depending on the type of said
functional group. For example, when the functional group is a
hydroxyl or carboxyl group, the substituent group is preferably an
isocyanate or epoxy group. When the functional group is a carboxyl
group, then the substituent group is preferably an isocyanate or
epoxy group. When the functional group is an amino or a substituted
amino group, the substituent group is preferably an isocyanate or
the like. When the functional group is epoxy group, the substituent
group is preferred to be a carboxyl group. One substituent group is
contained in every molecule of the energy ray-polymerizable group
containing compound (a2).
[0065] Further, 1 to 5, and preferably 1 to 2 carbon-carbon double
bond of the energy ray-polymerizable group, is contained in the
energy ray-polymerizable group containing compound (a2). As
specific examples of the energy ray-polymerizable group containing
compound (a2); methacryloyloxyethyl isocyanate,
meth-isopropenyl-.alpha., .alpha.-dimethylbenzyl isocianate,
methacryloyl isocyanate, allyl isocyanate, glycidyl(meth)acrylate
and (meth)acrylic acid or so may be mentioned. Also, acryloyl
monoisocyanate compound obtained by reaction of a diisocyanate or
polyisocyanate compound with hydroxyethyl(meth)acrylate; acryloyl
monoisocyanate compound obtained by reaction of a mixture of a
diisocyanate or polyisocyanate compound, a polyol compound and
hydroxyethyl(meth)acrylate may be mentioned as well.
[0066] As for the energy ray-polymerizable group containing
compound (a2), an energy ray-polymerizable group containing
polyalkyleneoxy compound, as described in the following, can be
used as well.
##STR00005##
[0067] In the above formula, R.sup.1 is hydrogen atom or methyl
group, and preferably methyl group. R.sup.2 to R.sup.5 are each
independently hydrogen or alkyl group having 1 to 4 carbon atoms,
and preferably hydrogen. Further, n is an integer of 2 or higher,
and preferably 2 to 4. That is, since n is 2 or higher, in the
above energy ray-polymerizable group containing polyalkyleneoxy
compound includes 2 or more R.sup.2. In here, R.sup.2 which exists
2 or more, may be same or different from each other. This can be
said to R.sup.3 to R.sup.5 as well. NCO in the chemical formula 5
indicates isocyanate group.
[Synthesis of the Energy Ray-Curable Polymer (A)]
[0068] The energy ray-curable polymer (A) of the present invention
is obtained by reacting the radical generating group containing
polymer (a1) and the energy ray-polymerizable group containing
compound (a2) having a substituent group which reacts with the
functional group of said radical generating group containing
polymer (a1). Hereinafter, the production method of the energy
ray-curable polymer (A) of the present invention will be described,
particularly the example of using the acrylic copolymer as a main
skelton will be described. However, the energy ray-curable polymer
(A) of the present invention is not limited to those obtained by
the method of production described hereinafter.
[0069] When manufacturing the energy ray-curable polymer (A), the
energy ray-polymerizable group containing compound (a2) is used in
an amount of 100 to 5 equivalent amounts, preferably 70 to 10
equivalent amounts, and more preferably 40 to 15 equivalent
amounts, per 100 equivalent amounts of the functional group
containing monomer of the radical generating group containing
polymer (a1).
[0070] The reaction between the radical generating group containing
polymer (a1) and the energy ray-polymerizable group containing
compound (a2) is usually performed at room temperature and at
atmospheric pressure for 24 hours. It is preferable that this
reaction is carried out in a solution, for example, an ethyl
acetate solution in the presence of a catalyst such as dibutyltin
laurate.
[0071] As a result, the functional group present in the side chain
of the radical generating group containing polymer (a1) and the
substituent group in the energy ray-polymerizable group containing
compound (a2) reacts, and the energy ray-polymerizable group is
introduced into the radical generating group (a1); thereby the
acrylic energy ray-curable polymer (A) is obtained. In this
reaction the reactivity between the functional group and the
substituent group is usually 70% or more, preferably 80% or more,
and it is preferable that the non reacting functional group does
not remain in the energy ray-curable polymer (A).
[0072] When using the energy ray-polymerizable group containing
polyalkyleneoxy compound, the acrylic energy ray-curable polymer
(A) binding the energy ray-polymerizable group via the
polyalkyleneoxy compound is obtained.
[0073] The weight average molecular weight of the energy
ray-curable polymer (A) bonded with the energy ray-polymerizable
group and the radical generating group is preferably 300,000 to
1,600,000, and further preferably 400,000 to 900,000. Also, usually
1.times.10.sup.21 to 1.times.10.sup.24, preferably
5.times.10.sup.21 to 8.times.10.sup.23, and more preferably
1.times.10.sup.22 to 5.times.10.sup.23 of polymerizable groups are
contained per 100 g of the energy ray-curable polymer (A). Further,
usually 1.times.10.sup.20 to 1.times.10.sup.24, preferably
2.times.10.sup.20 to 5.times.10.sup.23, and more preferably
5.times.10.sup.20 to 2.times.10.sup.23 of the radical generating
groups are contained per 100 g of the energy ray-curable polymer
(A).
[The Energy Ray-Curable Adhesive Composition]
[0074] The adhesive composition of the energy ray-curable type is
obtained by blending the appropriate additives depending on the
needs to the energy ray-curable polymer of the present
invention.
[0075] As the additives, for example, the crosslinkers (B),
tackifier, pigment, dye, filler or so may be mentioned; however,
the adhesive composition may be the energy ray-curable polymer
alone and without the blending thereof.
[The Crosslinkers (B)]
[0076] As for the crosslinkers (B), for example, an organic
polyvalent isocyanate compound, an organic polyvalent epoxy
compound and an organic polyvalent imine compound or so may be
mentioned.
[0077] As for the above mentioned organic polyvalent isocyanate
compound, an aromatic polyvalent isocyanate compound, an aliphatic
polyvalent isocyanate, and an alicyclic polyvalent isocyanate
compound may be mentioned. As for further specific examples of the
organic polyvalent isocyanate compound; 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene
diisocyanate, diphenylmethane-4,4'-diisocyanate,
diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane
diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate,
dicyclohexylmethane-4,4'-diisocyanate,
dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate or so
may be mentioned. A trimer of these polyvalent isocyanate compounds
or an isocyanate terminated urethane prepolymer obtained by
reacting these polyvalent isocyanate compounds with a polyol
compound may be used as well.
[0078] As for specific examples of the above organic polyvalent
epoxy compound, for example, a bisphenol A epoxy compound, a
bisphenol F epoxy compound,
1,3-bis(N,N-diglycidylaminomethyl)benzene,
1,3-bis(N,N-diglycidylaminomethyl)toluene,
N,N,N'N'-tetraglycidyl-4,4-diaminodiphenylmethane or so may be
mentioned.
[0079] As specific examples of the above organic polyvalent imine
compound, a N,N'-diphenylmethane-4,4'-bis(1-azridinecarboxyamide),
trimethylolpropane-tri-.beta.-aziridinyl propionate,
tetramethylolmethane-tri-.beta.-aziridinyl propionate
N,N'-toluene-2,4-bis(1-aziridinecarboxyaminde)triethylenemelamine
or so may be mentioned.
[The Formation of the Energy Ray-Curable Adhesive Composition]
[0080] The used amount of above mentioned crosslinkers (B) is
preferably 0.01 to 20 parts by weight and particularly preferably
0.1 to 10 parts by weight, with respect to 100 parts by weight of
the energy ray-curable polymer (A).
[0081] As for the energy ray-curable adhesive composition formed as
such, there is no need to further add the photo polymerization
initiator or the low molecular weight compound such as the energy
ray-polymerizable compound to the energy ray-curable polymer (A),
since the energy ray-curable polymer (A) its self comprises the
function as the photo polymerization initiator and the function as
the energy ray polymerization compound. Therefore, according to the
energy ray-curable adhesive composition of the present invention,
the amount of the low molecular weight included in the adhesive
composition is significantly reduced, thus can solve various
problems such as the compositional change along with the
volatilization of the low molecular weight, and the generation of
the volatile gas or so.
[0082] However, the photo polymerization initiator, the energy
ray-polymerizable low molecular weight compound, pigment, dye,
filler or so may be included in said adhesive agent as far as it
does not compromise the object of the present invention. Among
these, the low molecular weight compound having a molecular weight
of 1000 or less may be included at a ratio of 3 weight % or less in
the adhesive agent.
[The Adhesive Sheet]
[0083] The adhesive sheet of the present invention is obtained by
adhering the adhesive layer obtained from the adhesive composition
of the present invention to the substrate. Also, depending on the
needs, the release film may be used in order to protect the
adhesive layer.
[The Substrate]
[0084] The substrate used in the adhesive sheet of the present
invention is not particularly limited, and a polyethylene film, a
polypropylene film, a polybutene film, a polybutadiene film, a
polymethylpentene film, a polyvinyl chloride film, a vinyl chloride
copolymer film, a polyethylene terephthalate film, a polybutylene
terephthalate film, a polyurethane film, an ethylene/vinyl acetate
copolymer film, an ionomer resin film, an ethylene/(meth)acrylic
acid copolymer film, an ethylene/(meth)acrylic acid ester copolymer
film, a polystyrene film, a polycarbonate film, a fluoro resin
film, a low density polyethylene (LDPE) film, a linear low density
polyethylene (LLDPE) film, or hydrogenated and modified film
thereof may be used. Also, the crosslinking film thereof may be
used as well. The above mentioned substrate may be alone, or it may
be a composite film combining two or more thereof.
[0085] The thickness of the substrate varies depending on the use,
however, it is usually 20 to 500 .mu.m, and preferably 50 to 300
.mu.m or so.
[0086] For example as described hereinafter, when the ultraviolet
ray is used as the energy ray applied to cure the adhesive, among
the above mentioned substrates, the one which is transparent to the
ultraviolet ray is preferable. Also, when the electron beam is used
as the energy ray, the substrates do not have to be transparent;
hence addition to the films mentioned in the above, the opaque film
by coloring them may be used.
[The Release Film]
[0087] As the release film, various films having the surface of a
release property are used. As specific examples of such release
film, a polyethylene film, a polypropylene film, a polybutene film,
a polybutadiene film, a polymethylpentene film, a polyvinyl
chloride film, a vinyl chloride copolymer film, a polyethylene
terephthalate film, a polybutylene terephthalate film, a
polyurethane film, an ethylene/vinyl acetate film, an ionomer resin
film, an ethylene/(meth)acrylic acid copolymer film, an
ethylene/(meth)acrylic acid ester copolymer film, a polystyrene
film, a polycarbonate film, a fluorocarbon resin film, a low
density polyethylene (LDPE) film, a linear low density polyethylene
(LLDPE) film, and hydrogenated and modified substrate thereof may
be used. Also, the crosslinking film thereof may be used as well.
The above mentioned film may be alone, or it may be a composite
film combining two or more thereof.
[0088] As the release film, the film in which the release treatment
is performed on to the one of the surface of above mentioned film
is preferable. A release agent used for the release treatment is
not particularly limited; however, a silicone type, a fluorine
type, an alkyd type, an unsaturated polyester type, a polyolefin
type, a wax type or so may be used. Particularly, the silicone
release agent is preferable since it can attain low releasing
force. If the film used as the release film has weak surface
tension by itself, and has low releasing force to the adhesive
layer, such as the polyolefin film, then there is no need for the
release treatment.
[0089] As the method of the release treatment, the release agent is
coated using a gravure coater, a meyer-bar coater, an air knife
coater, or a roll coater or so to said film without the solvent, or
by solvent diluting or emulsifying. Then, the release agent is
heated, or irradiated with the ultraviolet ray or the electron beam
for curing, thereby the release layer is formed.
[0090] The thickness of the above release film is preferably 12
.mu.m or thicker, more preferably 15 to 1000 .mu.m, and
particularly preferably 50 to 200 .mu.m. When the release film is
too thin, the dimensional stability of the adhesive sheet itself
becomes insufficient, against the stress accumulating during the
steps of stacking each layer constituting the adhesive sheet and
the step of winding the adhesive sheet. If the release layer is too
thick, the whole thickness of the adhesive sheet becomes too thick,
hence it becomes difficult to handle.
[The Manufacturing of the Adhesive Sheet]
[0091] The adhesive sheet of the present invention comprises the
above mentioned energy ray-curable adhesive composition and the
substrate. The adhesive sheet of the present invention is obtained
by coating the energy ray-curable adhesive agent with the
appropriate thickness on various substrates in accordance with the
generally known methods such as a roll knife coater, a comma
coater, a gravure coater, a die coater, a reverse coater or so;
then the adhesive layer is formed by drying, followed by
superimposing the release film on the adhesive layer depending on
the needs. Also, the adhesive sheet may be manufactured by
providing the adhesive layer on the release film and transferring
these onto said substrate.
[0092] The thickness of the adhesive layer varies depending on the
use; however it is usually 5 to 100 .mu.m, and preferably 10 to 40
.mu.m or so. If the adhesive layer becomes thin, the adhesive
property and the surface protection function may decline.
[0093] The adhesive sheet of the present invention can lower the
adhesive force by the energy ray irradiation, and as for the energy
ray, specifically the ultraviolet ray and the electron beam or so
are used. Also the irradiation amount varies depending on the type
of the energy ray, and for example when using the ultraviolet ray,
the ultraviolet ray intensity is 50 to 300 mW/cm.sup.2 or so, and
the ultraviolet ray irradiation amount is preferably 100 to 1200
mJ/cm.sup.2 or so.
[0094] The energy ray-curable adhesive layer used in the present
invention has sufficient adhesive force before the energy ray
irradiation; hence the semiconductor wafer can be securely held
during the semiconductor wafer processing step such as backside
grinding and dicing or so.
[0095] Said energy ray-curable adhesive layer cures by the energy
ray irradiation and the adhesive force significantly declines. For
example, the adhesive force against the mirror surface of the
semiconductor wafer is preferably 2000 to 15000 mN/25 mm and
further preferably 5000 to 10000 mN/25 mm or so before the energy
ray irradiation, on the other hand after the irradiation, it is 1
to 50% or so of that of before the irradiation.
[The Processing Method of the Semiconductor Wafer]
[0096] The adhesive sheet of the present invention can be used for
processing the semiconductor wafer as described in the
following.
(The Wafer Backside Grinding Method)
[0097] During the backside grinding of the wafer, the wafer
processing adhesive sheet is stuck to the circuit face of the
semiconductor wafer formed with the circuit on the front surface in
order to protect the circuit surface while the backside grinding of
the wafer and to have a predetermined thickness of the wafer.
[0098] The semiconductor wafer can be a silicon wafer, or a
compound semiconductor wafer such as gallium arsenide. The
formation of the circuit on the wafer surface can be performed by
conventionally widely used various methods such as an etching
method and a lift off method or so. The predetermined circuit is
formed during the circuit forming step of the semiconductor wafer.
The thickness of such wafer at before the grinding is not
particularly limited; however it is usually 500 to 1000 .mu.m or
so.
[0099] Then, during the backside grinding, the adhesive sheet of
the present invention is stuck to the circuit surface in order to
protect the circuit surface. The backside grinding is performed by
known methods using the grinder and the vacuum table or so for
fixing the wafer while the adhesive sheet is stuck. After the
backside grinding step, the treatment to remove the fractured layer
due to the grinding may be performed.
[0100] After the backside grinding step, the energy ray is
irradiated to the adhesive sheet to cure the adhesive agent for
reducing the adhesive force, then the adhesive sheet is released
from the circuit surface. The adhesive sheet of the present
invention has sufficient adhesive force before the energy ray
irradiation; hence the wafer is securely held during the backside
grinding of the wafer, and also can prevent the penetration of the
grinding water into the circuit surface. Also, the adhesive force
declines significantly after the adhesive agent is cured by the
energy ray irradiation; hence it can be easily released from the
circuit surface and the glue residue to the circuit surface can be
reduced.
[0101] Further, according to the energy ray-curable adhesive agent
of the present invention, the amount of the low molecular weight
compound included in the adhesive agent is significantly lowered;
hence there is no flow out of the low molecular weight due to the
grinding water.
(The Wafer Backside Processing Method)
[0102] Also, followed by said backside grinding step, various
processing are performed to the backside of the wafer.
[0103] For example, in order to further form the circuit pattern to
the backside of the wafer, the treatment involving the heat
generation such as an etching treatment or so may be performed.
Also, the die bond film may be heat pressed to the backside of the
wafer. During these steps, the circuit pattern can also be
protected by adhering the adhesive sheet of the present invention;
and, it will be exposed to a high temperature condition. However,
since the low molecular weight compounds is not substantially
included in the adhesive layer of the adhesive sheet of the present
invention, the volatilization of the low molecular weight compounds
by heat generation and heat application during the processing can
be suppressed.
(The Wafer Dicing Method)
[0104] The adhesive sheet of the present invention has the property
which significantly reduces the adhesive force by the energy ray
irradiation, hence it may be used as the dicing sheet.
[0105] When using as the dicing sheet, the adhesive sheet of the
present invention is stuck to the backside of the wafer. The dicing
sheet is stuck generally by the apparatus called a mounter, however
it is not particularly limited.
[0106] The dicing method of the semiconductor wafer is not
particularly limited. As for an example, the method of forming
chips from a wafer by known methods such as a method using a
rotating round blade of a dicer or so after fixing the peripheral
portion of the dicing tape by the ring flame when dicing the wafer
may be mentioned. Alternatively, it may be a dicing method using a
laser light. According to the adhesive sheet of the present
invention, the amount of the low molecular weight compounds
included in the adhesive layer can be significantly reduced; hence
the low molecular weight compounds does not flow out due to the
grinding water.
[0107] Next, the energy ray is irradiated to the adhesive sheet and
the adhesive agent is cured to reduce the adhesive force, then the
chips are picked up from the adhesive sheet. The chips picked up
are then die bonded by usual method and resin sealed thereby the
semiconductor apparatus is manufactured. According to the adhesive
sheet of the present invention, the glue residue and the
contamination due to the low molecular weight compound to the
backside of the chips are reduced; hence no adverse effect due to
the residue of the chip backside occurs.
[0108] Hereinabove, the energy ray-curable polymer of the present
invention, particularly when using as the main component of the
adhesive layer in the wafer processing adhesive sheet was explained
as an example, however the energy ray-curable polymer of the
present invention may be used besides the above mentioned, and for
example it may be used as the molding resin, adhesive bond, paint
and ink or so which has a adverse effect due to the volatilization
component.
EXAMPLE
[0109] Hereinafter the present invention will be described based on
the examples; however the present invention is not limited
thereto.
Example 1
[0110] (Synthesis of the Radical Generating Group containing
Monomer)
[0111] The radical generating group containing monomer was obtained
by mixing and reacting,
1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one
(made by Ciba speciality chemical Inc., product name "IRGACURE
2959") and methacryloyloxyethyl isocyanate at the same molar
ratio.
(Synthesis of the Radical Generating Group containing Polymer)
[0112] The acrylic radical generating group containing polymer was
synthesized by a solution polymerization in ethyl acetate solution
using; 57 parts by weight of butyl acrylate, 10 parts by weight of
methylmethacrylate, 28 parts by weight of 2-hydroxyethylacrylate as
the functional group containing monomer, and 5 parts by weight of
the radical generating group containing polymerizable monomer
formed in the above. 2,2-`azobisisobutylonitrile was used as the
polymerization initiator, and 2,4-diphenyl-4-methyl-1-pentene was
used as the chain transfer agent. (Hereinafter, if not particularly
mentioned, the above mentioned polymerization initiator and the
chain transfer agent during the synthesis of the radical generating
group containing polymerizable copolymer are used).
(Formation of the Energy Ray-Curable Polymer)
[0113] 100 parts by weight, in terms of the solid portion, of this
acrylic radical generating group containing polymer and 30 parts by
weight of methacryloyloxyethyl isocyanate (80 equivalent amounts
with respect to 100 equivalent amounts of the hydroxyl group as a
functional group of the acrylic radical generating group containing
polymer) were reacted and obtained ethyl acetate solution (30%
solution) of the acrylic energy ray-curable polymer having weight
average molecular weight of 630,000 formed by bonding the
polymerization group and radical generating group.
(Formation of the Energy Ray-Curable Adhesive Composition)
[0114] With respect to 100 parts by weight of this acrylic energy
ray-curable polymer, 0.625 parts (solid portion) by weight of the
polyvalent isocyanate compound (made by Nippon Polyurethance Co.,
product name "Coronate L") were mixed to obtain the acrylic energy
ray-curable adhesive composition.
(Formation of the Adhesive Sheet)
[0115] The above mentioned adhesive composition was coated, so that
the thickness of the coat is 40 .mu.m after the drying, by using
the roll knife coater to the surface of the polyethylene
telephtalate film (thickness of 38 .mu.m) which is silicone release
treated as the release sheet. Next, after drying at 100.degree. C.
and 120.degree. C. for 2 minutes, then polyethylene film having
thickness of 110 .mu.m as the substrate was stacked to the obtained
adhesive layer, thereby the adhesive sheet was obtained. In order
to stabilize the adhesive force, it was left under the atmosphere
of 23.degree. C.50% RH for 7 days, and then the following physical
property and the ability were evaluated.
"The Adhesive Force"
[0116] The adhesive force of the obtained adhesive sheet was
measured as follows.
[0117] The adhesive force of the adhesive sheet was measured by
using Universal Testing Instruments (TENSILON/UTM-4-100, made by
ORIENTEC CO., LTD) at the releasing speed of 300 mm/min, and
releasing angle of 180.degree. following JIS Z0237, besides the
mirror surface of the silicon wafer was the adherend, and the
adhesive force before curing was determined.
[0118] Also, after the adhesive sheet was stuck to the mirror
surface of the silicon wafer, it was left under the atmosphere of
23.degree. C.50% RH for 20 minutes, and the ultraviolet ray
irradiation was performed (irradiation condition: intensity 350
mW/cm.sup.2, amount of light 200 mJ/cm.sup.2) from the substrate
side of the adhesive sheet by using the ultraviolet irradiation
apparatus (made by LINTEC Corporation, product name "RAD-2000").
The adhesive force was measured as similar as the above in regards
with the adhesive sheet after the ultraviolet ray irradiation, and
the adhesive force after the energy ray irradiation was
determined.
"The Surface Contamination Property"
[0119] The surface contamination property when using the above
mentioned adhesive sheet as the surface protection sheet during the
backside grinding of the semiconductor wafer was evaluated as the
following.
[0120] The above mentioned adhesive sheet was stuck to the
patterned surface of the silicon dummy wafer (thickness: 725 .mu.m,
surface status: comprises the circuit pattern having 20 .mu.m step
difference at maximum), by using the tape laminator (made by LINTEC
Corporation, product name "RAD-3510"). Then, by using the wafer
backside grinding apparatus (made by Disco Corporation, product
name "DGP-8760"), the wafer thickness was ground till it becomes
100 .mu.m thick. Next, the ultraviolet ray irradiation was
performed (irradiation condition: intensity 350 mW/cm.sup.2, amount
of light 200 mJ/cm.sup.2) by using the ultraviolet irradiation
apparatus (made by LINTEC Corporation, product name "RAD-2000")
from the substrate of the adhesive sheet. Next, by using the tape
mounter (made by LINTEC Corporation, product name "RAD-2000F/12"),
the dicing tape (made by LINTEC Corporation, product name "D-185")
was stuck to the grinding surface, then said adhesive sheet was
released from the circuit surface.
[0121] Next, the circuit surface of the silicon dummy wafer was
observed using the digital microscope (made by KEYENCE CORPORATION,
product name "Digital microscope VHX-200") at 2000 magnification.
When the adhesive residual was not found, the surface contamination
property was evaluated "good", and when the residual was found, the
surface contamination property was evaluated "bad".
"The Weight Reduction Rate (The Volatile Gas Amount) after
Heating"
[0122] The weight reduction rate after heating was evaluated by
measuring the weight reduction using the differential
thermal.cndot.thermalgravity simultaneous instrument (made by
SHIMADZU CORPORATION, product name "DTG-60"). A piece of the above
mentioned adhesive sheet (0.01 g; release film was removed) was
raised up to 120.degree. C. at 10.degree. C./min, followed by
heating at 120.degree. C. for 60 minutes, then returned to room
temperature and determined the weight reduction rate of before and
after the heating.
Example 2
[0123] The acrylic radical generating group containing polymer was
synthesized by solution polymerizing in ethyl acetate solution,
using 68.2 parts by weight of butyl acrylate, 10 parts by weight of
methyl methacrylate, 16.8 parts by weight of
2-hydroxyethylacrylate, and 5 parts by weight of the radical
generating group containing monomer prepared in the example 1. 100
parts by weight, in terms of the solid portion, of this radical
generating group containing polymer and 18.7 parts by weight
methacryloyloxyethyl isocyanate (83.3 equivalent amount with
respect to 100 equivalent amount hydroxyl group as a functional
group of the acrylic radical generating group containing polymer)
were reacted, and obtained ethyl acetate solution (30% solution) of
the energy ray-curable polymer having a weight average molecular
weight of 680,000 formed by bonding the polymerization group and
radical generating group.
[0124] With respect to 100 parts by weight of this energy
ray-curable polymer, 0.625 parts by weight (solid portion) of the
polyvalent isocyanate compound (made by Nippon Polyurethance Co.,
product name "Coronate L") were mixed to obtain the energy
ray-curable adhesive composition.
[0125] The same procedures were performed as the example 1 except
for forming the adhesive layer by using the above mentioned
adhesive composition. The results are shown in Table 1.
Example 3
[0126] The acrylic radical generating group containing polymer was
synthesized by solution polymerizing in ethyl acetate solution
using, 68.2 parts by weight of butyl acrylate, 10 parts by weight
of methyl methacrylate, 16.8 parts by weight of
2-hydroxyethylacrylate, and 1 parts by weight of the radical
generating group containing monomer prepared in the example 1. 100
parts by weight, in terms of the solid portion, of this radical
generating group containing polymer and 18.7 parts by weight of
methacryloyloxyethyl isocyanate (83.3 equivalent amount with
respect to 100 equivalent amount hydroxyl group as a functional
group of the acrylic radical generating group containing polymer)
were reacted, and obtained ethyl acetate solution (30% solution) of
the energy ray-curable polymer having weight average molecular
weight of 680,000 formed by bonding the polymerization group and
radical generating group.
[0127] With respect to 100 parts by weight of this energy
ray-curable polymer, 0.625 parts by weight (solid portion) of the
polyvalent isocyanate compound (made by Nippon Polyurethance Co.,
product name "Coronate L") were mixed to obtain the energy
ray-curable adhesive composition.
[0128] The same procedures were performed as the example 1 except
for forming the adhesive layer by using the above mentioned
adhesive composition. The results are shown in Table 1.
Comparative Example 1
(Formation of the Adhesive Composition)
[0129] The acrylic copolymer was synthesized by solution
polymerizing in ethyl acetate solution using, 62 parts by weight of
butyl acrylate, 10 parts by weight of methyl methacrylate, and 28
parts by weight of 2-hydroxyethylacrylate. 100 parts by weight, in
terms of the solid portion, of this acrylic copolymer and 30 parts
by weight of methacryloyloxyethyl isocyanate (80 equivalent amount
with respect to 100 equivalent amount hydroxyl group as a
functional group of the acrylic copolymer) were reacted, and
obtained ethyl acetate solution (30% solution) of the acrylic
copolymer having weight average molecular weight of 600,000 formed
by bonding the polymerizable group via an alkylene oxide group.
[0130] With respect to 100 parts by weight of this acrylic
copolymer, 0.625 parts by weight (solid portion) of the polyvalent
isocyanate compound (made by Nippon Polyurethance Co., product name
Coronate L), and 3.3 parts by weight (solid portion) of the
photopolymerization initiator (made by Ciba speciality chemical
Inc., product name IRGACURE 184) were mixed and obtained the
adhesive composition.
[0131] The same procedures were performed as the example 2 except
for forming the adhesive layer by using the above mentioned
adhesive composition. The results are shown in Table 1.
Comparative Example 2
[0132] The acrylic copolymer was synthesized by solution
polymerizing in ethyl acetate solution using, 73.2 parts by weight
of butyl acrylate, 10 parts by weight of methyl methacrylate, and
16.8 parts by weight of 2-hydroxyethylacrylate. 100 parts by
weight, in terms of the solid portion, of this acrylic copolymer
and 18.7 parts by weight of methacryloyloxyethyl isocyanate (83.3
equivalent amount with respect to 100 equivalent amount hydroxyl
group as a functional group of the acrylic copolymer) were reacted,
and obtained ethyl acetate solution (30% solution) of the acrylic
adhesive polymer having weight average molecular weight of 600,000
formed by bonding the polymerization group via the alkylene oxide
group.
[0133] With respect to 100 parts by weight of this acrylic adhesive
polymer, 0.625 parts by weight (solid portion) of the polyvalent
isocyanate compound (made by Nippon Polyurethance Co., product name
Coronate L), and 3.3 parts by weight (solid portion) of the
photopolymerization initiator (made by Ciba speciality chemical
Inc., product name IRGACURE 184) were mixed and obtained the
adhesive composition.
[0134] The same procedures were performed as the example 2 except
for forming the adhesive layer by using the above mentioned
adhesive composition. The results are shown in Table 1.
Comparative Example 3
[0135] The acrylic copolymer having weight average molecular weight
of 600,000 was synthesized by solution polymerizing in ethyl
acetate solution using, 73.2 parts by weight of butyl acrylate, 10
parts by weight of methyl methacrylate, and 16.8 parts by weight of
2-hydroxyethylacrylate. 100 parts by weight, in terms of the solid
portion, of this acrylic copolymer and 18.7 parts by weight of
methacryloyloxyethyl isocyanate (83.3 equivalent amount with
respect to 100 equivalent amount hydroxyl group as a functional
group of the acrylic copolymer) were reacted, and obtained ethyl
acetate solution (30% solution) of the acrylic adhesive polymer
formed by bonding the polymerization group via the alkylene oxide
group.
[0136] With respect to 100 parts by weight of this acrylic adhesive
polymer, 0.625 parts by weight (solid portion) of the polyvalent
isocyanate compound (made by Nippon Polyurethance Co., product name
Coronate L), and 3.3 parts by weight (solid portion) of the
photopolymerization initiator (made by Ciba speciality chemical
Inc., product name IRGACURE 184) were mixed and obtained the
adhesive composition.
[0137] The same procedures were performed as the example 2 except
for forming the adhesive layer by using the above mentioned
adhesive composition. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Surface The weight reduction Adhesive force
mN/25 mm) Contamination rate after heating (The Adhesive Layer
Adhesive Layer Property out gas amount) (%) 100.degree. C. during
120.degree. C. during 100.degree. C. 120.degree. C. 100.degree. C.
120.degree. C. the drying the drying during during during during
Before After Before After the the the the curing curing curing
curing drying drying drying drying Example 1 9300 230 9000 240 Good
Good -1.09 -1.10 Example 2 12000 280 11500 290 Good Good -1.04
-1.03 Example 3 8000 400 8300 420 Good Good -1.06 -1.06 Comparative
9200 280 9900 800 Good Bad -5.15 -4.21 example 1 Comparative 13100
320 12300 950 Good Bad -5.21 -4.32 example 2 Comparative 12100 350
11000 1150 Good Bad -5.18 -4.23 example 3
* * * * *