Semiconductor device having a junction capacitance, an integrated injection logic circuit and a transistor in a semiconductor body

Claim 1

A semiconductor device having a junction capacitance, an integrated injection logic circuit and a transistor in a semiconductor body, comprising: a semiconductor layer of a first conductivity type which is formed on a semiconductor substrate of a second conductivity type opposite to said first conductivity type, an isolation region which extends from a surface of said semiconductor layer to said substrate and which isolates said semiconductor layer into a first island region, a second island region, and a third island region, a first semiconductor buried layer of said first conductivity type which is located between said first island region and said substrate, said first semiconductor buried layer having a higher impurity concentration than said first island region, a second semiconductor buried layer of said first conductivity type which is located between said second island region and said substrate and which has an impurity concentration lower than that of said first semiconductor buried layer, said second semiconductor buried layer having a thickness greater than that of said first semiconductor buried layer, a third semiconductor buried layer of said first conductivity type which is located between said third island region and said substrate, and which has an impurity concentration higher than that of said first buried layer, a first semiconductor region of a second conductivity type which is selectively formed in said second island region and is contacted with said second semiconductor buried layer, second and third semiconductor regions of said second conductivity type which are formed in said third island region in a manner to be spaced from each other, a fourth semiconductor region of said first conductivity type which is formed in said second semiconductor region, a fifth semiconductor region of said second conductivity type which extends from a surface of said first island region toward but is separated from said first buried layer, and a sixth semiconductor region of said first conductivity type which is formed in said fifth semiconductor region, a junction capacitance being formed by a PN junction between said first semiconductor region and said second semiconductor buried layer, an integrated injection logic circuit being constructed of said third semiconductor buried layer, said third island region, said second semiconductor region, said third semiconductor region and said fourth semiconductor region, a transistor being constructed of said first island region, said fifth semiconductor region and said sixth semiconductor region, and wherein said first semiconductor buried layer contains a first impurity for defining said first conductivity type, said second semiconductor buried layer contains a second impurity for defining said first conductivity type and said third semiconductor buried layer contains said first and second impurities.