Method of Manufacturing a Semiconductor Integrated Circuit Device Which Includes at Least One v-Groove Jfet and One Bipolar Transistor

1. A method of manufacturing a semiconductor integrated circuit device which includes at least one junction field-effect transistor and at least one bipolar transistor, comprising the steps of: a. preparing a semiconductor substrate, having one principal surface with a plurality of isolated regions of a first conductivity type, extending thereinto from the one principal surface; b. simultaneously diffusing an impurity of a second conductivity type, opposite said first conductivity type, from said one principal surface into one of said isolated regions and into another of said isolated regions in order to form a first semiconductor region for a base region of said bipolar transistor in the one isolated region and to form a second semiconductor region for a channel region of said junction field-effect transistor in the other isolated region, thereby forming said first and second semiconductor regions having the same depth; c. etching a selected part of said second semiconductor region in order to form a groove within said second semi-conductor region; and d. diffusing an impurity of said first conductivity type simultaneously from said one principal surface into a selected part of said first semiconductor region and into a selected part of said second semiconductor region including the groove portion in order to form a third semiconductor region for an emitter region of said bipolar transistor within said first semiconductor region and to form a fourth semiconductor region for a gate region of said junction field-effect transistor within said second semiconductor region, thereby forming said fourth semiconductor region for the gate region deeper than said third semiconductor region for the emitter region from said one principal surface of the semiconductor substrate.

2. The method of manufacturing a semiconductor integrated circuit device as defined in claim 1, wherein said one principal surface of said semiconductor substrate has a crystal orientation of silicon in the {100} face, and said groove portion is V-shaped in cross-section.

3. In a method of manufacturing a semiconductor integrated circuit device which includes at least one junction field-effect transistor and at least one bipolar transistor, and includes the steps of: a. providing a semiconductor substrate having first and second isolated regions of a first conductivity type which extend to a first principal surface of said substrate; b. simultaneously diffusing an impurity of a second conductivity type, opposite said first conductivity type, into selected surface portions of said first and second isolated regions, respectively, so as to form third and fourth semiconductor regions of said second conductivity type; and c. simultaneously diffusing an impurity of said first conductivity type into selected surface portions of said third and fourth semiconductor regions, respectively, to form fifth and sixth semiconductor regions of said first conductivity type; said first, third and fifth semiconductor regions being the collector, base, and emitter regions of a bipolar transistor, and the distance between said first and fifth regions defining the base width and the current gain h.sub.FE of said bipolar transistor; said fourth and sixth semiconductor regions being the respective gate and channel regions of a junction type field-effect transistor, and the distance between said sixth region and said second region controlling the pinch-off voltage V.sub.p of said junction field-effect transistor, the improvement comprising a method for reducing the pinch-off voltage V.sub.p to a value smaller than the base-emitter reverse breakdown voltage V.sub.BE of said bipolar transistor without reducing the base width and increasing the current gain h.sub.FE of said bipolar transistor comprising the step of i. forming a groove in a selected surface portion of said fourth semiconductor region; and ii. forming said sixth region in step (c) by diffusing an impurity of said first conductivity type in the surface portion of said fourth region at the bottom of said groove therein, so that said sixth region extends deeper into said fourth region from said first principal surface than said fifth region extends into said third region.

4. The improvement according to claim 3, wherein said first principal surface of said substrate has the crystal orientation of the {100} face of silicon, and said groove is V-shaped in cross-section.