Browse Prior Art Database

Narrow Base Lateral PNP Bipolar Fabrication Using Angle Implant Technique

IP.com Disclosure Number: IPCOM000122577D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Gambino, J: AUTHOR [+5]

Abstract

Ion implantation at a large tilt angle (45 degree) has been used to fabricate FETs with asymmetric dopant profile under the gate edge (1). One benefit of the angle implant is that the effective channel length is reduced by about 0.3 um compared to device fabricated with conventional implants. We propose using large tilt angle implants to fabricate the emitter and collector of lateral bipolar transistors. The angled implants are expected to improve the LPNP performance in two aspects: First, narrower base widths can be achieved than with conventional implantation, resulting in a shorter base transit time. In addition, there is more freedom to tailor the transistor profiles than with conventional implants, and thereby avoid problems such as punch- through, current crowding and impact ionization.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 55% of the total text.

Narrow Base Lateral PNP Bipolar Fabrication Using Angle Implant Technique

      Ion implantation at a large tilt angle (45 degree) has
been used to fabricate FETs with asymmetric dopant profile under the
gate edge (1).  One benefit of the angle implant is that the
effective channel length is reduced by about 0.3 um compared to
device fabricated with conventional implants. We propose using large
tilt angle implants to fabricate the emitter and collector of lateral
bipolar transistors.  The angled implants are expected to improve the
LPNP performance in two aspects:  First, narrower base widths can be
achieved than with conventional implantation, resulting in a shorter
base transit time.  In addition, there is more freedom to tailor the
transistor profiles than with conventional implants, and thereby
avoid problems such as punch- through, current crowding and impact
ionization.

      A possible process for a lateral pnp transistor using a large
tilt angle implant is described below:
      1.   The processing is similar to a conventional implanted LPNP
up to collector/emitter implant.
      2.   Angle implants form the extension of the emitter and
collector underneath the base mask.
      3.   Annealing of both implants (vertical implant and angle
implant) can be done either together or individually to achieve an
uniform base profile.
      4.   Open base reach-through contact using RIE and form
silicide on the exposed silicon surface.
...