Appeal No. 2001-1559
Application No. 09/237,174
BACKGROUND
Appellants’ invention is directed to a process for making a
laterally insulated buried layer in a semiconductor substrate
using deep trench isolation technology. A trench having at least
one shallow region and at least one deep region is formed in the
substrate through a reference layer, the substrate and the buried
layer (specification, page 4). The trench is then filled with
silicon oxide in an ozone-activated CVD process (specification,
page 5). Thus, by selecting the material of the reference layer
and the ratio of a width of the deep region to a step height of
the shallow region, the two regions of the trench can be filled
while the deposited insulation material maintains a planar top
surface (specification, page 8).
Representative independent claim 1 is reproduced below:
1. A process for fabricating a buried, laterally insulated
zone of increased conductivity in a semiconductor substrate,
having the following steps:
providing a silicon substrate with a buried zone of
increased conductivity;
forming a reference layer on the substrate;
patterning the reference layer;
forming a trench with at least one shallow region and at
least one deep region in the substrate; and
2
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