U.S. patent application number 11/968669 was filed with the patent office on 2008-05-01 for rework process for removing residual uv adhesive from c4 wafer surfaces.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Steven R. Codding, Timothy C. Krywanczyk, Edward J. Sprogis, Jocelyn Sylvestre, Matthew R. Whalen.
Application Number | 20080099149 11/968669 |
Document ID | / |
Family ID | 37902446 |
Filed Date | 2008-05-01 |
United States Patent
Application |
20080099149 |
Kind Code |
A1 |
Codding; Steven R. ; et
al. |
May 1, 2008 |
REWORK PROCESS FOR REMOVING RESIDUAL UV ADHESIVE FROM C4 WAFER
SURFACES
Abstract
A method for the removal of residual UV radiation-sensitive
adhesive from the surfaces of semiconductor wafers, remaining
thereon from protective UV radiation-sensitive tapes which were
stripped from the semiconductor wafers. Moreover, provided is an
arrangement for implementing the removal of residual sensitive
adhesive, which remain from tapes employed as protective layers on
semiconductor wafers, particularly wafers having surfaces including
C4 connections.
Inventors: |
Codding; Steven R.;
(Underhill Center, NY) ; Krywanczyk; Timothy C.;
(Essex Junction, VT) ; Sprogis; Edward J.;
(Underhill, VT) ; Sylvestre; Jocelyn; (Granby,
CA) ; Whalen; Matthew R.; (Chelsea, VT) |
Correspondence
Address: |
SCULLY, SCOTT, MURPHY & PRESSER, P.C.
400 GARDEN CITY PLAZA
SUITE 300
GARDEN CITY
NY
11530
US
|
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
New Orchard Road
Armonk
NY
10504
|
Family ID: |
37902446 |
Appl. No.: |
11/968669 |
Filed: |
January 3, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11243882 |
Oct 4, 2005 |
|
|
|
11968669 |
Jan 3, 2008 |
|
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|
Current U.S.
Class: |
156/382 |
Current CPC
Class: |
H01L 21/02057 20130101;
H01L 21/67028 20130101; H01L 21/67132 20130101 |
Class at
Publication: |
156/382 |
International
Class: |
B32B 37/12 20060101
B32B037/12 |
Claims
1-12. (canceled)
13. An arrangement for the removal of residual UV adhesive deposits
from the surface of a semiconductor wafer, said arrangement
comprising: a vacuum chamber containing a pressure-sensitive UV
cure tape in close parallel position with said surface of the
semiconductor wafer; a subatmospheric vacuum condition being formed
in said vacuum chamber so as to cause said pressure-sensitive UV
tape to engage said semiconductor wafer surface in close surface
contact; means for treating of said UV cure tape so as to reduce
tacking thereof with said semiconductor wafer surface; and said UV
cure tape being peeled from said semiconductor wafer surface,
wherein said adhesive deposits remain adherent to said tape and are
removed from said semiconductor wafer surface in conjunction with
the peeling off of said tape.
14. An arrangement, as claimed in claim 13, wherein said UV cure
tape is treated with a 10% IPA solution during application to the
surface of said semiconductor wafer.
15. An arrangement, as claimed in claim 13, wherein said UV cure
tape is applied to the front surface of said semiconductor wafer so
as to closely adhere to electronic components and C4 connections
arranged on said front surface for removing said adhesive residue
deposits remaining on said surface, components and C4 connections
from preceding protective tapes, which were applied during
processing of the backside of said semiconductor wafer.
16. An arrangement, as claimed in claim 15, wherein said processing
of the backside comprises grinding said back surface of the
semiconductor wafer for the thinning of said wafer.
17. An arrangement, as claimed in claim 13, wherein said tape
comprises a UV cure tape which is applied to the front surface of
said wafer.
18. An arrangement, as claimed in claim 13, wherein a UV cure tape
is repeatedly applied a plurality of times to said wafer front
surface for effectuating a complete removal, as required, of said
adhesive residue deposits from said wafer surface.
19. An arrangement, as claimed in claim 13, wherein said front
surface is subjected to a cleaning with N.sub.2 gas after the
peeling off of said UV cure tape from said surface.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for the removal of
residual UV radiation-sensitive adhesive from the surfaces of
semiconductor wafers, remaining thereon from protective UV
radiation-sensitive tapes, which were stripped from the
semiconductor wafers. The invention further resides to an
arrangement for implementing the removal of residual sensitive
adhesive, which remain from tapes (hereinafter referred to as UV
tapes) employed as protective layers on semiconductor wafers,
particularly wafers having surfaces including C4 connections.
[0003] In the present state of the technology which is directed to
the manufacture of semiconductor wafers, and especially but not
limited to semiconductor wafers, which are employed for the
incorporation of collapsed control chip connections (C4s) it is
becoming necessary that in view of thermal dissipation problems and
packaging requirements which necessitate the employment of thinner
dies formed from such semiconductor wafers, that special measures
be taken to protect the wafer surfaces and the electronic elements
and C4 connections located thereon. Generally, the process of
thinning the semiconductor wafers, referred to as C4 wafers,
entails the application of a protective adhesive tape as is
commonly employed in the industry, onto the surface of the
semiconductor wafers having the electronic components and
connections located thereon, so as to protect the components and
the C4 connections during the semiconductor wafer thinning
procedure. Ordinarily, the thinning process is carried out by means
of suitable grinding and polishing the obverse or back side of the
wafer creating dust and particulate debris from which the front
wafer surface is to be protected by the tape. Upon completion of
the thinning of the wafer, the adhesive tape is generally exposed
to ultraviolet light in order to deactivate he adhesive of
ultraviolet light-sensitive adhesive tape and thereby reduce the
level of tackiness of the tape to the front surface of the
semiconductor wafer on which it is positioned. Upon completion of
the tape to UV radiation exposure, which facilitates the release of
the tape from the surface of the semiconductor wafer, the tape is
peeled off from the front surface of the wafer covering the
electronic components and from the C4 connections. However, during
the initial wafer taping, or lamination procedure in applying the
UV radiation or light-sensitive tape onto the surface of the
semiconductor wafer and also during the delamination thereof, i.e.,
the detaping or tape peeling procedure, problems may be encountered
which adversely effect the UV tape deactivation, and which may
cause residual adhesive material from the tape to remain on the
semiconductor wafer surface.
[0004] Among such problems are the formation of gaseous or air
bubbles between the surface of the semiconductor wafer and the
applied protective tape, which are formed during the lamination of
the latter to the surface of the wafer, the formation of UV
bulb-like configurations, resulting in a non-uniform lamination
being produced about the surface of the semiconductor wafer, and in
an improper UV radiation exposure prior to implementing the
delamination or peeling of the UV radiation-sensitive adhesive tape
from the surface of the semiconductor wafer. As a result of these
problems, upon occasion residual adhesive from the UV tape remains
adherent to the surface of the wafer and to the C4 connections
during delamination and peeling off of the UV tape. The removal of
such residual adhesive is quite difficult and not always readily
achievable, whereby attempts have been made to utilize a known
solvent, such as an NMP, IPA, S/N or the like, which are not always
efficacious and frequently fail to remove some or all the adhesive
residue. The use of stronger solvents or a process of sputtering
may result in damage being encountered by the materials of the
electronic components, the C4 connections, aluminum pads on the
wafer, and the polyimide composition of the semiconductor wafer
during exposure thereto. This, at times, renders the entire
semiconductor device being processed non-usable and may lead to
economic losses in implementing the manufacturing process.
[0005] 2. Discussion of the Prior Art
[0006] Various publications have to be directed to the application
of protective tapes to semiconductor wafers or the like, however,
none of which are deemed pertinent with regard to the inventive
concept.
[0007] David, et al., U.S. Pat. No. 6,872,268 B2 disclose a method
of conforming an adherent film and pertains to applying a tape to a
substrate and also employing a vacuum to closely adhere the tape to
the surface of the substrate.
[0008] Yamamoto, U.S. Pat. No. 6,716,295 B2 relates to the
application of a protective tape to a substrate and thereafter
separating the latter from a substrate by employing a two-tape
system for application and then subsequent delamination in an
attempt to avoid the formation of tape adhesive residues. However,
there is no process of removing such adhesive residues in a simple
and clean manner analogous to that of the present invention.
[0009] McKenna, U.S. Pat. No. 6,007,654 relates to a non-contact
method of adhering a wafer to a wafer tape, and wherein this is
essentially implemented in a non-contacting manner through the
application of a gas jet which forces the tape against the surface
of the wafer or substrate.
[0010] Ametani, U.S. Pat. No. 5,310,442 describes an apparatus for
respectively applying and removing a protective adhesive tape from
a substrate, such as a semiconductor wafer, and does not concern
itself with the removal of any remaining adhesive residue through a
method analogous with described by the invention.
[0011] Mochizuki, U.S. Pat. No. 5,246,533 describes an apparatus
for the press-bonding of a tape onto the edges of a workpiece.
There is no disclosure of any aspect for removing residual adhesive
from the surface of a semiconductor mounting electronic components
which were located underneath a protective tape that has been
peeled off the surface.
[0012] Wellings, et al., U.S. Pat. No. 5,106,439 disclose an
application of coverings to a substrate surface, wherein the
coverings are applied to the substrate under pressure and/or a
vacuum is a sequentially employed manner. There is no disclosure of
a method for removing residual adhesive from the surface of a
semiconductor wafer, which has remained thereon subsequent to the
removal of a protective adhesive tape.
[0013] Finally, Nakao, U.S. Pat. No. 4,714,511 describes a method
and apparatus for adhering a tape or a sheet to a semiconductor
wafer, however, which does not pertain to a method of attempting
the removal of residual adhesive from the tape on the surface of
the semiconductor wafer.
SUMMARY OF THE INVENTION
[0014] Accordingly, in order to obviate the disadvantages and
drawbacks, which are encountered in the prior art during the
removal or peeling away of the previously applied adhesive tape,
such as UV tape, from the surface of a semiconductor wafer wherein
the tape has been employed to protectively cover the electronic
elements and/or C4 connections and pads thereon from debris or
contaminants, and wherein residual adhesive material from the tape
remains adherent to the surface of the semiconductor wafer, and on
the electronic components, it is the purpose of the present
invention to cleanse the surface of the semiconductor wafer,
electronic components and C4 connections are pads from the presence
of the residual adhesive without any damage being encountered by
the wafer surface and/or components.
[0015] In order to achieve the foregoing surface cleansing effect,
pursuant to one aspect of the invention, UV tape is reapplied to
the residual adhesive-containing wafer surface utilizing a vacuum
system. The vacuum system is adapted to prevent any air pockets
from forming around the C4s and any other electronic components
intermediate the facing surfaces of the semiconductor wafer and of
the UV tape. This, in effect, will permit the newly applied UV tape
to completely and uniformly adhere to the residual UV adhesive
remaining on the wafer surface from the precedingly removed
adhesive tape or UV tape. The subsequent exposure of the wafer and
reapplied tape to UV radiation now fully deactivates the UV
adhesive and facilitates delamination of the reapplied UV tape so
as to enable all previous residual adhesive to be removed from the
wafer and components surfaces. If necessary, the foregoing may be
repeated subject to inspection until any remaining residual
adhesive has been fully removed.
[0016] Pursuant to an alternative aspect of the invention, a UV
tape is reapplied to the residual adhesive-containing surface of
the semiconductor wafer in that the tape facing the semiconductor
wafer surface, or the latter has a 10% IPA (Isopropyl Alcohol)
solution applied thereto. This eliminates any air pockets or the
formation of bubbles from being created around the C4 connections
or at any other location on the wafer surface. The solution is
applied prior to the application of the tape, thereby inhibiting
the entrapment of air about the C4 connections on the wafer
surface.
[0017] Accordingly, it is an object of the present invention to
provide a method for the removal of residual UV adhesive remaining
from a previously applied protective tape on a wafer surface, which
was peeled from the surface of the semiconductor wafer.
[0018] Another object of the present invention resides in the
provision of a novel method for reapplying a UV tape to the surface
of a semiconductor wafer having electronic elements and C4
connections thereon so as to remove residual adhesive material
therefrom, through the intermediary of a vacuum arrangement and
then applying a UV treatment to be able to again remove the UV tape
in conjunction with any residual adhesive from the surface of the
semiconductor wafer.
[0019] Yet another object of the invention resides in the provision
of a method for reapplying a UV tape to the surface of a
semiconductor wafer having electronic elements and C4 connections
thereon so as to remove residual adhesive materials therefrom,
through the application of a solution containing any IPA (Isopropyl
Alcohol) or equivalent liquid prior to or during tape application
so as to inhibit the entrapment of air about the C4 connections or
the formation of air pockets and bubbles.
[0020] Another object resides in the provision of a vacuum
arrangement for enabling the removal of residual adhesive from
previously applied UV tapes from the surface of a C4 semiconductor
wafer through a reapplication of UV tape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Reference may now be made to the following detailed
description of a preferred embodiment of the invention, taken in
conjunction with the accompanying drawings; in which:
[0022] FIG. 1 illustrates, generally diagrammatically, an
arrangement for applying a UV-sensitive adhesive tape to -the
surface of a semiconductor wafer through the utilization of a
vacuum;
[0023] FIG. 2 illustrates the presence of residual adhesive from
the UV tape on C4 connections on the surface of a semiconductor
wafer; and
[0024] FIG. 3 illustrates the semiconductor wafer surface
subsequent to the residual adhesive having been removed from the
surface and the C4 connections.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Referring now in specific detail to the drawings,
illustrated in FIG. 1 is a vacuum arrangement 10, including a
vacuum housing 12 having a chamber 14 in which a length of UV
adhesive tape 16 having an adhesive surface layer 18 may be
positioned. The adhesive surface layer 18 is adapted to be
subjected to UV radiation so as to enable the reduction of its
adhesive properties, as described hereinbelow. A semiconductor
wafer 20 is arranged within the confines of the chamber 14 in close
parallel relationship with the adhesive surface of the UV tape 16.
The surface 22 of the semiconductor wafer 20 facing the UV tape 16
includes C4 connections 24, such as are shown in FIGS. 2 and 3 of
the drawings, and may also comprise various other electronic
circuit components, such as pads and the like (not shown), as is
well known in the technology. Surface portions of the surface 22 of
the semiconductor wafer 20 and regions about the C4 connections 24
may contain some residual UV adhesive material from preceding
protective layer of UV tape which protectively covered the wafer
surface 22 during previous manufacturing process steps, such as
during grinding and polishing of the reverse or back side of the
semiconductor wafer 20 in order to implement the thinning thereof,
as is known in the art.
[0026] After that previous process step has been completed, the
protective tape was subjected to UV light and delaminated, i.e.,
peeled off the wafer surface, which in some instances will leaves
an amount of UV adhesive material from the tape to remain adherent
to the surface of the semiconductor wafer 20 and also the C4
connections or bumps and other electronic components on the wafer.
Generally, as mentioned hereinabove, such adhesive residues are
difficult to remove through the intermediary of treatments with
solvents or other chemical and or heating methods, which may lead
to the potential damaging of the components and material of the
semiconductor wafer, and resultingly inoperable scrap.
[0027] In particular, referring again to FIG. 1 of the drawings, in
order to be able to remove such residual adhesive 26, the
semiconductor wafer 20 with the C4 connections 24 and any other
components are positioned so that the surface 22 thereof faces
upwardly into the arrangement from the bottom of the housing
chamber 14, and face towards a further UV adhesive tape 16 having
an adhesive layer facing the wafer, which is positioned in
parallel, closely spaced relationship therebelow.
[0028] Thereafter, a vacuum is applied by means of vacuum pump 30
connected to the chamber so as to create a subatmospheric pressure
in the chamber 14 of the housing 12 pulling the UV tape into close
surface area contact with the facing surface 22 of the
semiconductor wafer 20, and closely encasing the electronic
structures or elements thereon, including the C4 connections, in
the absence of the formation of any air gaps or bubbles. A liquid
may be present on the surface of the UV tape in the nature of a 10%
IPA solution to produce the inventive UV case tape 16. Gas may be
introduced into the chamber to further press the tape against the
wafer surface. Thereafter, the vacuum is released and the
semiconductor wafer, including the closely adherent UV cure tape
removed from the chamber, and UV radiation applied thereto in order
to eliminate or reduce the tacking effect between the semiconductor
surface and the tape, and the tape delaminated or peeled off. This
will cause the previously deposited residual UV adhesive to adhere
to the UV cure tape and be pulled away from the wafer surface 22 in
conjunction with the tape. Thereafter, if required, the surface of
the semiconductor device may optionally be subjected to a stream of
a gaseous cleaning medium, such as nitrogen or the like, in order
to further cleanse the surface and, the above procedure for the
removal of residual UV adhesive may be repeated, when warranted by
an inspection, in the case that any adhesive material residue is
still present on the surface of the semiconductor wafer and
components.
[0029] From the foregoing, it becomes readily apparent that it is
possible to remove contaminants or the like, such as are formed by
UV adhesive residues from a previously delaminated UV tape in the
absence of having to employ solvents or chemicals which may be
deleterious to the processing and integrity of the semiconductor
wafer or to the components and C4 connections arranged thereon.
[0030] As diagrammatically illustrated in FIG. 2 of the drawings,
there are shown C4 bumps 24 on the surface 22 of the semiconductor
wafer 20 with the protective tape having been removed and showing
residual strips of adhesive material remaining thereon. To the
contrary, shown in FIG. 3, subsequent to the reapplication of a UV
cure tape by means of operation of vacuum arrangement 10 and curing
and tape removal, this shows the areas free and clear of any such
adhesive residues, indicating that the surface of the semiconductor
wafer is in a clean condition.
[0031] In an alternative method to that described above, or in
addition thereto, the application of the UV 16 to the surface 22 of
semiconductor wafer 20 may be preceded by the application of a
liquid solvent, preferably such as a 10% solution of Isopropyl
Alcohol (IPA), between the tape and the wafer surface. This creates
an effect similar to that of the application of a vacuum, and
eliminates air pockets or bubbles from being created about the C4
connections or bumps 24 on the surface 22 of the wafer 20.
Consequently, this ensures a complete removal of residual adhesive
remaining from a previously peeled off tape.
[0032] Although, 10% solution of IPA is preferred, other solvents
and/or solution strengths can be contemplated, although this may
possibly raise compatibility issues with the semiconductor wafer
materials.
[0033] While the present invention has been particularly shown and
described with respect to preferred embodiments thereof, it will be
understood by those skilled in the art that the foregoing and other
changes in forms and details may be made without departing from the
scope and spirit of the present invention. It is therefore intended
that the present invention not be limited to the exact forms and
details described and illustrated, but fall within the scope of the
appended claims.
* * * * *