Browse Prior Art Database

Method to Make Bicmos Device Data Available Early in Process

IP.com Disclosure Number: IPCOM000119550D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Hook, TB: AUTHOR

Abstract

Device data is made obtainable relatively early in the process of making bipolar-complementary-metal-oxide-silicon (BICMOS) integrated circuits by doing an ion implant and drive-in after polysilicon definition. By removing a wafer from a lot and obtaining characteristics of both field-effect and bipolar devices early in the process, yield projections may be made, timely process corrections are possible, and savings are also realized when bad lots are found.

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Method to Make Bicmos Device Data Available Early in Process

      Device data is made obtainable relatively early in the
process of making bipolar-complementary-metal-oxide-silicon (BICMOS)
integrated circuits by doing an ion implant and drive-in after
polysilicon definition.  By removing a wafer from a lot and obtaining
characteristics of both field-effect and bipolar devices early in the
process, yield projections may be made, timely process corrections
are possible, and savings are also realized when bad lots are found.

      A cross-section of a bipolar device in Fig. 1 shows the
condition created by normal processing at the time a test wafer is
removed.  P-type substrate 10 has n+ doped region 12 with n- doped
region 14 disposed over it.  An opening in recessed oxide 18 exposes
n- layer 14 while another opening in oxide 18 defines p doped region
16.  N+ polysilicon 20 contacts p region 16 through a hole in oxide
22.

      Fig. 2 shows the result of performing an ion implant of p-type
dopant followed by a drive-in process on the region shown in Fig. 1.
P+ regions 24, 26, and 28 are thereby created and n+ dopant is driven
down from n+ polysilicon 20 into region 30, the remaining portion of
p doped region 16 shown in Fig. 1.  P+ region 24 provides collector
connection through a forward biased diode.  P+ regions 26 and 28
provide connection to the base of the NPN device. Polysilicon 20 is
the emitter connection through n+ junction 32.

      By pro...