Method of forming contacts to a semiconductor device

A method of forming electrical connections to a base contact, an emitter contact, and a subcollector reachthrough region of a bipolar transistor, comprising the steps of:

• forming a layer of etch stop material having a first etch characteristic over said base contact, emitter contact, and subcollector reachthrough region;
• forming a layer of dielectric material having a second etch characteristic conformally over said layer of etch stop material;
• simultaneously etching base contact and subcollector reachthrough vias through said layer of dielectric material using an etchant selective to said dielectric material so as to stop on said layer of etch stop material over said base contact and said subcollector reachthrough region;
• extending said base contact and subcollector reachthrough vias through said layer of etch sto material so as to expose the surfaces of said base contact and said subcollector reachthrough region;
• forming a mask over said base contact and subcollector reachthrough vias;
• etching an emitter contact via through said layer of dielectric material using an etchant selective to said dielectric material so as to stop on said layer of etch stop material over said emitter contact;
• extending said emitter contact via through said layer of etch stop material to the surface of said emitter contact;
• and
• removing said mask.