Use of oblique implantation in forming emitter of bipolar transistor
US5726069A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 2, 1994 |
| Grant date | Mar 10, 1998 |
| Priority date | — |
| Expiry date | Dec 2, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/133
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A bipolar transistor is fabricated by a process in which first and second dopants of the same conductivity type are introduced into a semiconductor body through at least partially overlapping sections, preferably the same section, of the body's upper surface to form an emitter. The first dopant is introduced at a greater dosage than the second dopant such that the emitter consists at least of a main emitter region constituted primarily with the first dopant. The introduction of the second dopant into the body entails ion implanting the second dopant at a tilt angle of at least 15.degree. relative to a direction generally perpendicular to the body's upper surface. Part of the second dopant is so implanted into an extension zone that extends laterally beyond the main emitter region. The extension zone may be of the same conductivity type as, or of opposite conductivity type to, the main emitter region. In either case, the extension zone is lightly doped and reduces transistor performance degradation by reducing the electric field along the emitter-base junction, especially along the upper semiconductor surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.