Ex parte Raleigh et al.

Board of Patent Appeals and Interferences

Aug 8, 2000

08354384 (B.P.A.I. Aug. 8, 2000)

1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered
today (1) was not written for publication in a law
journal and (2) is not binding precedent of the Board.
Paper No. 16
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte CARL RALEIGH and WILLIAM C. ROMAN
_____________
Appeal No. 1997-3390
Application No. 08/354,384
______________
ON BRIEF
_______________
Before JERRY SMITH, FLEMING, and HECKER, Administrative Patent
Judges.
FLEMING, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal from the rejection of claims
8 through 20. Claims 1 through 7 have been canceled.
Appellants’ invention is generally directed to a method
of forming metal layers for attachment to a heat sink in
semiconductor devices and in particular, to flame spraying a
heat spreading layer on the back surface of a semiconductor
die. As disclosed on page 5 of the specification and Figure
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Application No. 08/354,384
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2, molybdenum or tungsten layer 18, having a thermal
coefficient of expansion similar to that of semiconductor
wafer, is flame sprayed onto the back side of semiconductor
die 12. Appellants further disclose that metal layer 15 may
be optionally deposited on the back surface of the die before
depositing the heat spreading layer for improved adhesion or
contact resistance. The step of flame spraying which is
performed in less than a minute at a temperature below 200EC,
as disclosed on page 6 of the specification, minimizes damage
to the active regions with electrical properties that can be
adversely affected by extended exposure to high temperature.
Additionally, Appellants disclose on page 6 of the
specification that the semiconductor die with the flame
sprayed metallization layer is attached to a metal substrate
using low melting point solders.
Representative independent claim 8 is reproduced as
follows:
8. A method for fabricating a
semiconductor device with a flame sprayed heat
spreading layer comprising the steps of:
providing a semiconductor die having a
thermal coefficient of expansion and a back
surface;
providing a material having a thermal
coefficient of expansion similar to the
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thermal coefficient of expansion of the
semiconductor die; and
flame spraying a heat spreading layer of
the material on the back surface of the
semiconductor die.
Appeal No. 1997-3390
Application No. 08/354,384
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The Examiner relies on the following references:
Santangelo et al. (Santangelo) 5,342,793 Aug. 30,
1994
Merz et al. (Merz) 5,032,469 Jul. 16,
1991
Claims 8 through 20 stand rejected under 35 U.S.C. § 103
as being obvious over Santangelo and Merz.
Rather than repeat the arguments of Appellants and the
Examiner, reference is made to the brief and the answer for
the details thereof.
OPINION
After careful review of the evidence before us, we do not
agree with the Examiner that claims 8 through 20 are properly
rejected under 35 U.S.C. § 103. Accordingly, we reverse.
The Examiner has failed to set forth a prima facie case.
It is the burden of the Examiner to establish why one having
ordinary skill in the art would have been led to the claimed
invention by the express teachings or suggestions found in the
prior art, or by implications contained in such teachings or
suggestions. In re Sernaker, 702 F.2d 989, 995, 217 USPQ 1, 6
(Fed. Cir. 1983). "Additionally, when determining
obviousness, the claimed invention should be considered as a
whole; there is no legally recognizable ‘heart’ of the
Appeal No. 1997-3390
Application No. 08/354,384
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invention." Para-Ordnance Mfg. v. SGS Importers Int'l, Inc.,
73 F.3d 1085, 1087, 37 USPQ2d 1237, 1239 (Fed. Cir. 1995),
cert. denied, 519 U.S. 822 (1996) citing W.L. Gore & Assoc.,
Inc. v. Garlock, Inc., 721 F.2d 1540, 1548, 220 USPQ 303, 309
(Fed. Cir. 1983), cert. denied, 469 U.S. 851 (1984).
Appellants on page 5 of the brief argue that Santangelo
teaches merely a method for low pressure deposition of metal
layers on the back of a semiconductor substrate while Merz
discloses flame spraying for coating metal substrates such as
steel and copper. Appellants add that Merz does not provide
any suggestion to use flame spraying for forming a metal layer
on a semiconductor substrate. Additionally, Appellants on
page 6 of the brief point out that bead or grit blasting of
the substrate prior to flame spraying, as taught by Merz,
destroys the surface of the semiconductor substrate of
Santangelo. Appellants conclude that combining Merz with
Santangelo is neither possible nor suggested by any of the
references.
The Examiner on pages 4 and 5 of the answer responds to
Appellants’ arguments by stating that the reason to combine is
taught by Merz in column 3, lines 53 and 54 that any suitable
Appeal No. 1997-3390
Application No. 08/354,384
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substrate to which the coating will adhere can be used. The
Examiner further states that the references are combinable
since the step of bead or grit blasting to roughen the surface
is optional and may be omitted. The Examiner adds that
Santangelo teaches coating of a semiconductor substrate which
may be combined with the plasma spraying process of Merz since
both processes are performed at low temperatures and will not
affect the substrate.
The Federal Circuit states that "[t]he mere fact that the
prior art may be modified in the manner suggested by the
Examiner does not make the modification obvious unless the
prior art suggested the desirability of the modification." In
re Fritch, 972 F.2d 1260, 1266 n.14, 23 USPQ2d 1780, 1783-84
n.14 (Fed. Cir. 1992), citing In re Gordon, 733 F.2d 900, 902,
221 USPQ 1125, 1127 (Fed. Cir. 1984). It is further
established that "[s]uch a suggestion may come from the nature
of the problem to be solved, leading inventors to look to
references relating to possible solutions to that problem."
Pro-Mold & Tool Co. v. Great Lakes Plastics, Inc., 75 F.3d
1568, 1573, 37 USPQ2d 1626, 1630 (Fed. Cir. 1996), citing In
re Rinehart, 531 F.2d 1048, 1054, 189 USPQ 143, 149 (CCPA
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1976) (considering the problem to be solved in a determination
of obviousness). The Federal Circuit reasons in Para-Ordnance
Mfg. Inc. v. SGS Importers Int’l Inc., 73 F.3d 1085, 1088-89,
37 USPQ2d 1237, 1239-40 (Fed. Cir. 1995), cert. denied, 519
U.S. 822 (1996), that for the determination of obviousness,
the court must answer whether one of ordinary skill in the art
who sets out to solve the problem and who had before him in
his workshop the prior art, would have been reasonably
expected to use the solution that is claimed by the
Appellants.
We find that Santangelo is concerned with forming a metal
layer on the back surface of a semiconductor substrate for
improved adhesion to a heat sink as well as low contact
resistance. Santangelo specifically teaches in column 2,
lines 33 through 63 that an ion implantation step provides the
low resistance contact as the deposition of one or more metal
layers allow the back surface of the semiconductor substrate
be soldered to a metal substrate. We further find that
Santangelo refers generally to "depositing" metal layers and
does not specify a particular deposition method such as
Appellants’ flame spraying method. Turning to Merz, we find
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that a method of plasma spraying over metal substrates such as
steel or copper is disclosed. Merz teaches examples of
different applications for plasma sprayed metallization in
column 1, lines 14 through 25, as blades and other components
in turbines or chemical reaction vessels and pipes. Merz
further teaches in column 3, lines
62 through 65, that the substrate may be preferably treated by
bead or grit blasting to roughen the surface and provide a
strong adhesion. We note that Merz provides several tables
showing results of coating process for different substrate
samples which are specified as either steel or copper.
We do not agree with the Examiner that Merz’ flame
spraying metallization method may be used with the
semiconductor substrate of Santangelo, as recited in
Appellants’ claim 8, to avoid adverse effects on the
substrate. Merz is concerned with coating metal substrates
such as steel and copper to avoid corrosion in adverse
environments. However, Merz is silent with regard to flame
spraying as a low temperature coating that prevents adverse
effects on other substrate materials such as semiconductors.
Therefore, we find no reason for combining the coating process
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of Merz with Santangelo’s semiconductor substrate in view of
the different substrate materials or the preparation steps as
suggested by Merz. In particular, Merz in column 2, lines
42 through 47, specifies the feed powder as an alloy of
stainless steel and a refractory metal. Additionally, in
column 3, lines 62 through 65, Merz provides the preferred
blasting step that roughens and improves the surface adhesion
of a metal substrate such as steel and copper but does little
for a semiconductor substrate other than damaging its surface.
Neither the specific feed powder material nor the surface
preparation step would teach to one of ordinary skill in the
art to combine the processing steps of Merz with a
semiconductor substrate. We do not agree with the Examiner
that any substrate may simply be used for flame spraying as
Merz in column 3, lines 53 through 62, teaches that "[a]ny
suitable substrate" is preferably "metallic" or materials such
as "copper and steel." Merz further provides examples of
industrial grade steel that require different surface
treatment and coating process than a semiconductor substrate
as recited in Appellants’ independent claim 8.
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In view of the analysis above, we find no reason or
suggestion for combining Santangelo and Merz. We further find
that one of ordinary skill in the art would not have
reasonably used a process of flame sprayed metallization for
metal substrates as taught by Merz for forming a metal layer
on back of a semiconductor substrate as disclosed by
Santangelo. We note that the other independent claim 15
recites the step of flame spraying a metal layer on the back
surface of a semiconductor wafer similar to claim 8.
Accordingly, we reverse the rejection of claims 8 through 20
under 35 U.S.C. § 103 over Santangelo and Merz.
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Application No. 08/354,384
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In view of the foregoing, the decision of the Examiner
rejecting claims 8 through 20 under 35 U.S.C. § 103 is
reversed.
REVERSED

JERRY SMITH )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
MICHAEL R. FLEMING )
Administrative Patent Judge ) APPEALS AND
)
) INTERFERENCES
)
STUART S. HECKER )
Administrative Patent Judge )
MRF/sld
mds
Appeal No. 1997-3390
Application No. 08/354,384
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VINCENT B. INGBASSIA
ON SEMICONDUCTOR-INTELLECTUAL
PROPERTY DEPARTMENT
SEMICONDUCTOR COMPONETS INDUSTRIES, L.L.C.
5005 E. MCDOWELL ROAD - M/S A230
PHOENIX, AZ 85008