Appeal No. 96-3997
Application No. 08/173,953
The claimed invention relates to a breakdown type bipolar
diode incorporated in an integrated circuit.
Claim 6 is illustrative of the invention and reads as
follows:
6. A bipolar diode comprising:
an epitaxial layer of a first conductivity type formed on
a semiconductor substrate of a second conductivity type;
an impurity region of the first conductivity type formed
in a surface portion of the epitaxial layer;
a first impurity region of the second conductivity type
formed in the surface portion of the epitaxial layer in a
manner to contact with the impurity region of the first
conductivity type;
a second impurity region of the second conductivity type
formed in contact with the impurity region of the first
conductivity type and the first impurity region; and
an insulating layer formed over the surface of the
epitaxial layer to protect a junction end of the associated
regions;
wherein said second impurity region is formed in a region
shallower than a buried layer of the first conductivity type
formed between the epitaxial layer and the semiconductor
substrate, the second impurity region having a maximal
impurity concentration at a predetermined distance from the
surface of the epitaxial layer toward an inside of the
epitaxial layer and being higher in impurity concentration
than the first impurity region,
and
wherein a breakdown of a junction of the impurity region
of the first conductivity type and the second impurity region
is caused at a location shallower than the buried layer.
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