Method of fabricating double photoresist layer self-aligned heterojunction bipolar transistor
US5736417A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1996 |
| Grant date | Apr 7, 1998 |
| Priority date | — |
| Expiry date | May 13, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S148/143
Abstract
A heterejunction bipolar transistor and a method for fabricating an HBT with self-aligned base metal contacts using a double photoresist, which requires fewer process steps than known methods, while minimizing damage to the active emitter contact region. In particular, a photoresist is used to form the emitter mesa. The emitter mesa photoresist is left on and a double polymethylmethacrylate (PMMA) and photoresist layer is then applied. The triple photoresist combination is patterned to create a non-critical lateral alignment for the base metal contacts to the emitter mesa, which permits selective base ohmic metal deposition and lift-off. By utilizing the double photoresist as opposed to a metal or dielectric for masking, an additional photolithography step and etching step is eliminated. By eliminating the need for an additional etching step, active regions of the semiconductors are prevented from being exposed to the etching step and possibly damaged.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.