Browse Prior Art Database

Simplified Bipolar in Bi-CMOS

IP.com Disclosure Number: IPCOM000102687D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Antipov, I: AUTHOR

Abstract

This article describes a method for simplifying the introduction of a high quality bipolar device into CMOS processes. This is achieved by implanting the extrinsic base through the entire base region and later removing only that portion of it where the intrinsic base should go, thereby avoiding the topography introduced by the base polysilicon.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 62% of the total text.

Simplified Bipolar in Bi-CMOS

       This article describes a method for simplifying the
introduction of a high quality bipolar device into CMOS processes.
This is achieved by implanting the extrinsic base through the entire
base region and later removing only that portion of it where the
intrinsic base should go, thereby avoiding the topography introduced
by the base polysilicon.

      It is highly desirable, in the Bi-CMOS process, to minimize the
number of masking steps required to make bipolar devices.  Such
devices must, however, meet high performance requirements, e.g.,
having a high fT and a low Rb6 .  The following method for obtaining
bipolar devices in a CMOS process meets these requirements.

      All conventional process steps needed for bipolar and CMOS
devices are first completed on the wafer, e.g., subcollectors, EPI, N
and P wells, resistors and collector reach-thru.  Referring to Fig.
1, a layer of oxide (Si02) 1 is first formed on the substrate 2,
after which CMOS device areas are defined by etching oxide and
oxidizing to the gate oxide thickness.  Thin layers of polysilicon 3
and Si02 4 are then produced by chemical vapor deposition (CVD) or
oxidation, after which an extrinsic base (P+) region 5 is ion
implanted in the surface of the bipolar transistor region of the
substrate.  The emitter aperture is next reactive ion etched (RIE)
through the extrinsic base region and the (P) intrinsic base region
7, formed in the substrate exposed in...