Appeal No. 95-2454
Application No. 07/396,733
include transistors, diodes, resistors, etc. which are interconnected to form the desired circuit. In order for
the circuit to perform its function, the various components must be electrically isolated from each other
(except of course for the necessary conductive pathways which join the individual elements into the circuit).
The active and passive circuit elements of the circuit are formed within these electrically isolated regions
or pockets. Various techniques have been used for achieving the necessary isolation. Specification, p. 1,
lines 4-6. In the integrated circuits made by applicant’s method, electrical isolation between regions is
achieved by the combination of an underlying PN junction and channels of silicon dioxide which contacts
the PN junction. This structure can be seen from the much simplified and annotated version of applicant’s
Figure 4:
Applicant’s process begins with a doped silicon substrate. In the first part of the process,
a PN junction is formed. This is done by growing an epitaxial silicon layer on at least a portion of the
substrate to form a PN junction. Depending on the type of component desired, the epitaxial layer may be
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Last modified: November 3, 2007