Browse Prior Art Database

Simple Method to Fabricate Polysilicon Emitter Bipolar Devices

IP.com Disclosure Number: IPCOM000041855D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Anantha, NG: AUTHOR

Abstract

Problems related to the interface between polysilicon and single-crystal silicon in polysilicon emitter bipolar transistors is eliminated by an ion implantation method for forming a heavily doped polysilicon layer on top of the diffused single-crystal emitter region. The current gain (b) of bipolar devices can be increased by using a heavily doped polysilicon layer on top of the diffused single crystal region of the emitter. The increased current gain is primarily due to the reduced carrier mobility in the polysilicon region of the emitter. In conventional processing, heavily doped polysilicon is deposited over single-crystal silicon using chemical vapor deposition techniques. This leads to interfacial problems and irreproducible characteristics of devices. Polysilicon is not deposited in the present technique.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 72% of the total text.

Page 1 of 1

Simple Method to Fabricate Polysilicon Emitter Bipolar Devices

Problems related to the interface between polysilicon and single-crystal silicon in polysilicon emitter bipolar transistors is eliminated by an ion implantation method for forming a heavily doped polysilicon layer on top of the diffused single- crystal emitter region. The current gain (b) of bipolar devices can be increased by using a heavily doped polysilicon layer on top of the diffused single crystal region of the emitter. The increased current gain is primarily due to the reduced carrier mobility in the polysilicon region of the emitter. In conventional processing, heavily doped polysilicon is deposited over single-crystal silicon using chemical vapor deposition techniques. This leads to interfacial problems and irreproducible characteristics of devices. Polysilicon is not deposited in the present technique. Instead, part of the single-crystal region of the emitter is converted to amorphous silicon. This conversion is achieved by using heavy ion ion-implantation techniques. The method is as follows. Bipolar devices are fabricated using conventional double diffusion techniques. The emitter depth can be in the range of 1000-5000.~ After the emitter drive-in cycle just before the metallization step, the emitter region is selectively ion implanted with arsenic or argon ions. Selective implantation techniques are well known where a layer of photoresist or oxide or metal is used as a masking layer. Ion...