Semiconductor device in a thin active layer with high breakdown voltage

US5659190A · kind A · utility

Assignee

• Telefonaktiebolaget LM Ericsson (Publ) · SE

Inventor

• Andrej Litwin · Stockholm, SE

Key dates

• Filing date: Jun 26, 1996
• Grant date: Aug 19, 1997
• Expiry date: Jun 26, 2016

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D84/406

Abstract

A silicon substrate carries an isolating silicon dioxide layer and a relatively weakly and negatively doped monocrystalline silicon wafer. A component region is delimited in the wafer by an isolating layer. A bipolar transistor in the component region has a positively doped base region which includes a heavily and positively doped base connection and a heavily and negatively doped emitter. The transistor has a PN-junction at the underside of the base region and is series connected with a field effect transistor having a heavily and negatively doped drain connection. The component region is weakly doped and the distance from the PN-junction to the silicon dioxide layer is small so that a region will be readily depleted of charge carriers when applying voltages to the transistors. The voltages produce an electric field of low electrical field strength in the depleted region. This counteracts the breakthrough of a current between the base and the drain connection. The transistors withstand high voltages and require only half the space on the substrate required by corresponding earlier known transistors.