Bipolar transistor

US7135757B2 · kind B2 · utility

Assignee

• Infineon Technologies AG · DE

Inventors

• Reinhard Stengl · Stadtbergen, DE
• Thomas Meister · Taufkirchen, DE
• Herbert Schafer · Höhenkirchen-Siegertsbrunn, DE
• Martin Franosch · Munich, DE

Key dates

• Filing date: Aug 4, 2004
• Grant date: Nov 14, 2006
• Expiry date: Aug 4, 2024

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D10/421

Abstract

A bipolar transistor includes a first layer with a collector. A second layer has a base cutout for a base. A third layer includes a lead for the base. The third layer is formed with an emitter cutout for an emitter. An undercut is formed in the second layer adjoining the base cutout. The base is at least partially located in the undercut. In order to obtain a low transition resistance between the lead and the base, an intermediate layer is provided between the first and the second layer. The intermediate layer is selectively etchable with respect to the second layer. At least in the region of the undercut between the lead and the base, a base connection zone is provided that can be adjusted independent of other production conditions. The intermediate layer is removed in a contact region with the base.