Ex parte UEDA et al.

Board of Patent Appeals and Interferences

Aug 25, 1998

07982068 (B.P.A.I. Aug. 25, 1998)

Application filed November 23, 1992. According to Appellants this1
application is a continuation of application no. 07/624,519, filed December 7,
1990, which is a continuation of application no. 07/518,328, filed May 5,
1990, which is a continuation of application no. 07/376,374, filed July 5,
1989, which is a divisional of application no. 07/122,603, filed November 18,
1987, which is a continuation of application no. 06/509,055, filed June 29,
1983.
Administrative Patent Judge Raymond Cardillo who sat at the oral2
hearing has retired and Administrative Patent Judge Jerry Smith has been
substituted in his place in this Appeal. See, In re Bose, 772 F.2d 866, 227
USPQ 1 (Fed. Cir. 1985).
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was not written for publication in a law journal and (2) is not
binding precedent of the Board.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. 45
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte DAISUKI UEDA and HIROMITSU TAKAGI
_____________
Appeal No. 94-2080
Application 07/982,0681
______________
HEARD: June 13, 1995
_______________
Before HARKCOM, Vice-Chief Administrative Patent Judge,
JERRY SMITH and LEE, Administrative Patent Judges.2
LEE, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal under 35 U.S.C. § 134 from the
examiner's final rejection of claims 7-11. 1-6 have been
Appeal No. 94-2080
Application 07/982,068
2
canceled. No claim has been allowed.
References relied on by the Examiner
Castrucci et al. (Castrucci) 3,785,886 Jan. 15, 1974
Wickstrom 4,070,690 Jan. 24, 1978
Imaizumi et al. (Imaizumi) 4,278,987 Jul. 14, 1981
The Rejections on Appeal
Claims 7-11 stand finally rejected under 35 U.S.C. § 112,
first paragraph, as being without written description in the
specification.
Claims 7-11 stand finally rejected under 35 U.S.C. § 103 as
being unpatentable over Wickstrom, Imaizumi, and Castrucci.
The Invention
The invention is directed to a vertically oriented insulated
gate field effect transistor formed on a semiconductor substrate
having a (100) principal plane. A rectangular recess is formed
such that at least two side walls thereof make a 45 degree angle
against the (01˘) plane of the substrate. Claim 10 appears the
broadest and is reproduced below:
10. A power vertical insulated gate FET comprising:
a silicon substrate of high concentration n-type
conductivity having a principal (100) plane,
an epitaxially grown lower concentration n-type
epitaxial layer on said substrate,
Appeal No. 94-2080
Application 07/982,068
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a p-type layer formed on said epitaxially grown
n-type layer,
a high concentration n-type top layer formed on
said p-type layer,
a rectangular parallelepiped-shaped recess formed
in such a direction that its side walls make an
angle of 45 against the (Ol˘) plane of saido
substrate and in a manner that said side walls are
vertical to the (100) plane of said substrate and
further in a manner to penetrate to the p-type
layer and to reach the epitaxial layer from said
top layer,
an oxide film formed in said recess and on said
top layer,
an electrode opening formed at a part of said
oxide film on said top layer,
a gate electrode formed on a part of said oxide
film formed in said recess,
a source electrode of aluminum formed at said
electrode opening, and
a drain electrode formed on said substrate.
Independent claims 7 and 11 further specify that first and
second sidewalls of the recess are formed along (010) and (001)
planes. Claim 7 additionally requires that a high concentration
region is formed in at least one of the four corner parts of the
rectangular recess. Claims 8 and 9 each depend from claim 7.
Opinion
Appeal No. 94-2080
Application 07/982,068
4
The rejection for lack
of written description
The appellants evidently represent that there is a mistake
in the specification as filed. Specifically, according to the
appellants, the plane of the wafer facet 8 in Figure 2A should
not be (110) as shown, but (01˘). The (01˘) orientation is
nowhere explicitly indicated in the specification as filed, but
is recited in the appellants’ claims now on appeal. That is the
basis of the lack of written description rejection.
In our view, from the perspective of one with ordinary skill
in the art a mistake apparently exists, since the wafer surface
plane and the wafer facet plane should be perpendicular to each
other and yet the (100) and (110) planes are not at right angles
to each other. However, because the (100) plane has been
described in the prior art as the substrate plane, see Castrucci
and Imaizumi, one with ordinary skill in the art would have
recognized that the mistake is associated with the (110)
designation for the wafer facet plane. Thus, the question is --
what is the correct designation for the wafer facet 8?
In their brief, the appellants explained in two different
Appeal No. 94-2080
Application 07/982,068
5
ways why the wafer facet plane should be (01˘), based on the
(100) orientation of the substrate surface and the (010) and
(001) orientations of the rectangular shape cut into the
substrate. The examiner, however, evidently concluded that the
drawings or diagrams used in the explanations constitute new
matter and cannot be considered. The examiner is incorrect. As
the appellants correctly point out in their reply brief, the
arguments and presentations in the brief are not any portion of
the specification but are the arguments and explanations of the
appellants as to why the examiner has erred. Accordingly, the
explanations must be considered.
Based on the explanations, the appellants have, at the very
least, established a prima facie case why the wafer facet plane,
based on the orientations given for the various other planes in
the original specification, i.e., the substrate plane, and the
planes of the side walls of the rectangular recess, is the (01˘)
plane, and thus the (01˘) designation only makes explicit what is
implicit. The examiner has offered no evidence or valid
reasoning to refute the appellants’ contentions.
The test for determining compliance with the written
Appeal No. 94-2080
Application 07/982,068
6
description requirement is whether the disclosure of the
application as originally filed reasonably conveys to the artisan
that the inventor had possession at that time of the later
claimed subject matter, rather than the presence or absence of
literal support in the specification for the claim language.
Vas-Cath Inc. v. Mahurkar, 935 F.2d 1555, 1563, 19 USPQ2d 1111,
1116 (Fed. Cir. 1991); In re Kaslow, 707 F.2d 1366, 1375, 217
USPQ 1089, 1096 (Fed. Cir. 1983). Satisfaction of the written
description requirement does not require the description to be in
ipsis verbis antecedence in the originally filed application. In
re Lukach, 442 F.2d 967, 969, 169 USPQ 795, 796 (CCPA 1971).
For the foregoing reasons, we do not sustain the rejection
of claims 7-11 under 35 U.S.C. § 112, first paragraph, as being
without written description in the original specification.
The obviousness rejection based on
Wickstrom, Imaizumi, and Castrucci
We do not sustain this ground of rejection.
Wickstrom discloses a vertical field effect transistor
structure built on the sides of finger-like mesas only the
central portion of which is described as being substantially
vertical. Also, it does not identify or discuss the orientation
Appeal No. 94-2080
Application 07/982,068
7
of the finger-like mesas relative to any specific crystal lattice
plane, or the orientation of the principal plane. That
deficiency is recognized by both the appellants and the examiner.
Castrucci, on the other hand, discloses a conventional non-
vertical transistor structure formed with a (100) oriented
principal substrate plane. But the appellants are correct that
even if the teachings of Wickstrom and Castrucci are reasonably
combinable, which we think it is, it only would reasonably have
suggested using the (100) crystal plane as the principal plane.
The appellants have advanced no reason why the same principal
plane orientation used for conventional non-vertical transistor
structures may not be used for vertical transistor structures.
Assuming that the principal substrate surface plane is the
(100) plane in Wickstrom, there are still many possible
orientations for the side walls of the finger-like mesas, not
necessarily aligned with the (010) or (001) crystal plane, or
with a plane at 45E angle to the (01˘) plane, as is required by
the appellants’ claims. On this record, the examiner has not
presented sufficient evidence that one with ordinary skill in the
art would have deemed obvious to orient the finger-like mesas of
Wickstrom in a direction such that their side walls are aligned
Appeal No. 94-2080
Application 07/982,068
8
in the manner as is required by the appellants’ claims. While it
is true that the finger-like mesas have to be oriented in some
direction, but without specific evidence, it cannot simply be
assumed that the appellants’ claimed orientation either is well
known in the art at the time of the invention or otherwise would
have been obvious to one with ordinary skill in the art.
Additionally, we note that the curved recesses between
Wickstrom’s finger-like mesas are not exactly the rectangular
parallelpiped recesses called for by the appellants’ claims.
The examiner’s discussion on page 4 of the answer with
regard to Imaizumi is not understood and appears erroneous.
According to the examiner (p.4, lines 2-4), Imaizumi’s Figure 10
illustrates that on a (100) plane surface a rectangular groove 94
can be formed at a 45 degree angle to the <100> direction. Also
according to the examiner (p.4, lines 16-20), evidently based
also on Figure 10 of Imaizumi, a groove with the desired side
walls can be formed on a (100) surface oriented wafer with an
anisotropic etch through a rectangular window whose sides make a
45 degree angle with the <110> direction of the substrate wafer.
Both positions are misplaced.
Figure 10 of Imaizumi shows two rectangular windows 94 and
95 on a substrate having a surface plane orientation (100). The
Appeal No. 94-2080
Application 07/982,068
9
first window has side walls rising in the <100> direction of the
crystal axis, and the second window 95 has side walls rising in
the <110> direction which is at 45 degrees relative to the
direction of the side walls of the first window 94. Figure 10
does not illustrate anything specific about (1) the orientations
of segments AD and BC, or AB and DC, or (2) the angle between
segment AD or BC, and the wafer facet edge, or (3) the specific
orientation of the wafer facet edge. See the discussion of
Figure 10 in Imaizumi’s column 8, lines 49-64.
Other findings of the examiner are also without support and
are incorrect. In the answer, on page 4, lines 7-10, it is
stated that "due to rotation, the (010) and (001) surfaces may be
considered equivalent to the (100) upper surface and may be so
designated." It should be noted that these planes are ordinarily
perpendicular to each other as is shown in Figure 2B of the
appellants’ specification, and that is not changed by any amount
of rotation of the device as a whole. It is without basis to
conclude that these planes are equivalents, especially when the
appellants’ claims specify different elements to be on different
planes. Finally, the examiner has read the appellants’ claims as
though it recites the (110) plane, rather than the (01˘) plane,
Appeal No. 94-2080
Application 07/982,068
10
as the plane making a 45 degree angle with a pair of side walls
of the rectangular recess. That is inappropriate, since the
claims recite the (01˘) plane and not the (110) plane.
In any event we further agree with the appellants that
Imaizumi’s subject matter is too remote from that of Wickstrom’s
invention to have a meaningful significance. The rectangular
recess formed in Imaizumi is intended to be filled in to form an
area of extra thickness, and the objective in Imaizumi is to form
an epitaxial layer with a very even top surface but different
thicknesses in different parts thereof. It is unclear and has
not been well explained by the examiner why it would have been
obvious to one with ordinary skill in the art to use Imaizumi's
teachings on the finger-like mesas of Wickstrom.
The initial burden is on the examiner to establish a prima
facie basis to reject the claims. In re Oetiker, 977 F.2d 1443,
1445, 24 USPQ2d 1443, 1444 (Fed. Cir. 1992); In re Piasecki, 745
F.2d 1468, 1472, 223 USPQ 785, 788 (Fed. Cir. 1984). The
examiner must provide an adequate factual basis to support an
obviousness conclusion. In re Warner, 379 F.2d 1011, 1016, 154
USPQ 173, 178 (CCPA 1967). Here, the examiner has failed to
present a reasonable explanation as to why the evidence
Appeal No. 94-2080
Application 07/982,068
11
establishes a prima facie case of obviousness. The necessary
burden has not been met.
Additionally, with respect to independent claim 7 and claims
8 and 9 which depend from claim 7, these claims require a region
of high [dopant] concentration in at least one of the four corner
parts of the rectangular recess. In our view, this feature must
reasonably be construed so as to require a higher dopant
concentration in at least one corner of the recess than that
generally in the non-corner areas of the recess. Th examiner
stated that in Wickstrom a high concentration N+ region extends
to all corners of the groove. However, that does not satisfy the
claimed feature as we have construed.
For all of the foregoing reasons, we do not sustain the
rejection of claims 7-11 under 35 U.S.C. § 103 as being
unpatentable over Wickstrom, Imaizumi, and Castrucci.
Conclusion
The rejection of claims 7-11 under 35 U.S.C. § 112, first
paragraph, as being without written description in the
specification is reversed.
The rejection of claims 7-11 stand under 35 U.S.C. § 103 as
Appeal No. 94-2080
Application 07/982,068
12
being unpatentable over Wickstrom, Imaizumi, and Castrucci is
reversed.
REVERSED
GARY V. HARKCOM )
Vice-Chief )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
JERRY SMITH ) APPEALS AND
Administrative Patent Judge ) INTERFERENCES
)
)
)
JAMESON LEE )
Administrative Patent Judge )
Appeal No. 94-2080
Application 07/982,068
13
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