Appeal No. 1997-3916
Application No. 08/429,650
buried anti-punchthrough implant channel which is narrower than the gate electrode" is not met by
Miyamoto. We are not persuaded by the examiner's assertion (answer,
page 7) that claim 25 does not preclude the formation of other regions abutting anti-punchthrough region.
We agree that the claim dos not preclude the formation of other regions abutting the anti-punchthrough
region. However, we find that the anti-punchthrough region is high concentration layers (6) and (7). We
do not consider Miyamoto to fairly suggest that the buried layer which forms the anti-punchthrough implant
channel to be narrower than the gate electrode.
The examiner relies upon Makino to provide the deficiencies in Miyamoto. While the examiner
only relies upon Makino for a teaching of an LDD structure as part of the source/drain region, we find
Makino to be closer to appellants claimed invention than the other references relied upon by the examiner.
Makino recognizes (figure 4, pages 5 and 18) that in the prior art, an attempt was made to prevent
punchthrough current in an FET by providing a high concentration layer (104) which extends across the
active area. While punchthrough current was reduced, the junction breakdown strength declined (page 6).
The purpose of Makino's invention (page 6) was to achieve higher performance by depressing a
punchthrough current without increasing the capacitance nor reducing the junction breakdown strength.
Makino's invention is to provide a high concentration region (4) formed of a buried layer of implanted
boron ions (figure 2 and page 8) to prevent punchthrough. Makino states (page 9) that the electrode (7) is
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