Appeal No. 95-4159
Application 08/151,055
expected to have lifetime killers in order to operate as a PT
device. Although the examiner attempts to dismiss features of
claim 1 as being directed to the process of making the
product, the presence or absence of lifetime killers in the
device is a structural distinction which is known to affect
the performance of the device. Therefore, Fay’s epitaxial
layers 13 and 14 cannot simply be equated with a single
substrate having the properties recited in claim 1.
Appellant also argues that the collective teachings of
Fay and Laska do not teach or suggest that a third diffused
region of at least 2 microns should be implanted on the
backside of the substrate [brief, pages 7-9]. It is the
examiner’s position that since the P-type collector region of
Fay is thicker than 5 microns, if the P-type region of Fay
were created by diffusion as taught by Laska, then this
diffused P-type region would also have a thickness greater
than 5 microns. Appellant notes that Laska discloses no
dimensions for his third diffused region, and the Laska
teachings of an NPT IGBT would not have been combined with the
Fay PT IGBT for determining dimensions of layers in two
disparate devices such as this. We agree with appellant.
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