Appeal No. 2003-0868 2
Application No. 09/710,101
THE INVENTION
The invention is directed to a high voltage transistor formed on a semiconductor
substrate. According to the inventors, the transistor includes a spiral resistor on top of a
thin oxide layer placed on a semiconductor substrate. One end of the spiral resistor is
connected to the highest potential of the transistor and the other end is connected to the
lowest potential in the resistor. A drift region underneath the spiral transistor is graded by
the presence of a single dopant. See Brief, page 3. Additional limitations are described in
the following illustrative claim.
THE CLAIM
Claim 1 is illustrative of appellant’s invention and is reproduced below.
1. A high voltage transistor formed on a semiconductor substrate, the
transistor comprising:
a thin gate oxide layer formed over said substrate;
a gate formed atop said gate oxide layer;
a drain formed in said substrate and separated from said gate by a drift region;
a source formed in said substrate adjacent to said gate;
a spiral resistor formed atop said gate oxide layer, said spiral resistor located
between said drain and said gate, wherein a first end of said spiral resistor is connected to
said drain and a second end of said spiral resistor is connected to said source; and
wherein said drift region is located in said substrate underneath said spiral resistor
and includes at least two dopant zones, each of said dopant zones having different dopant
concentrations, further wherein said drift region only includes one type of dopant.
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