Bipolar transistor with base-collector-isolation without dielectric

US8067290B2 · kind B2 · utility

Assignee

• Infineon Technologies AG · DE

Inventors

• Josef Boeck · Putzbrunn, DE
• Wolfgang Liebl · Bad Abbach, DE
• Thomas Meister · Taufkirchen, DE
• Herbert Schaefer · Herdorf, DE

Key dates

• Filing date: Dec 18, 2009
• Grant date: Nov 29, 2011
• Expiry date: Mar 11, 2030

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D62/137

Abstract

The disclosed invention provides a method for the fabrication of a bipolar transistor having a collector region comprised within a semiconductor body separated from an overlying base region by one or more isolation cavities (e.g., air gaps) filled with low permittivity gas. In particular, a multilayer base-collector dielectric film is deposited over the collector region. A base region is formed onto the multilayer dielectric film and is patterned to form one or more base connection regions. The multilayer dielectric film is selectively etched during a plurality of isotropic etch processes to allow for the formation of one or more isolation region between the base connection regions and the collector region, wherein the one or more isolation regions comprise cavities filled with a gas having a low dielectric constant (e.g., air). The resultant bipolar transistor has a reduced base-collector capacitance, thereby allowing for improved frequency properties (e.g., higher maximum frequency operation).