Appeal No. 1998-0970
Application 07/995,325
Griswold discloses a method of diffusing an active
impurity into a semiconductor body. An impurity, such as
boron, is deposited at relatively low temperatures at which no
diffusion of the active impurity material into the
semiconductor body can occur (col. 3, lines 13-20).
Thereafter, a layer of an oxide of a semiconductor material is
deposited over the active impurity material at a relatively
low temperature such that no diffusion of the previously
deposited active impurity atoms occurs during deposition
(col. 3, lines 20-28). Subsequently, the semiconductor
material having the layers of active impurity and oxide of
semiconductor material thereover is subjected to substantially
high temperatures to diffuse the active impurity material into
the semiconductor body (col. 3, lines 28-33). The oxide of
semiconductor contains the deposited boron material in contact
with the exposed surface of the semiconductor material and
prevents it from escaping into the atmosphere within the
diffusion furnace (col. 7, lines 53-57). Griswold discloses
"that the temperatures utilized during the method steps of the
present process are quite low, namely, 350E C. for the
deposition of the impurity material and 600E C. for the
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