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SOI Lateral Bipolar Transistor with Poly-spacer Formed Base Contact

IP.com Disclosure Number: IPCOM000108919D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Davari, B: AUTHOR [+4]

Abstract

Disclosed is the structure and technique to obtain a lateral structure with a very narrow base contact poly width, which would result in both reduced collector resistance, and also reduced base-collector capacitance. The reduction of the collector resistance is caused by a very thin base poly, which is defined by a non-lithographic method, and thus allows sub-resolution poly widths. The structure obtained is shown in Figs. 1a and 1b.

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SOI Lateral Bipolar Transistor with Poly-spacer Formed Base Contact

       Disclosed is the structure and technique to obtain a
lateral structure with a very narrow base contact poly width, which
would result in both reduced collector resistance, and also reduced
base-collector capacitance.  The reduction of the collector
resistance is caused by a very thin base poly, which is defined by a
non-lithographic method, and thus allows sub-resolution poly widths.
The structure obtained is shown in Figs. 1a and 1b.

      To fabricate the structure, one should start with n-doped SOI.
About 50 nm of polysilicon and 200 nm of LTO are deposited.  The LTO
is etched at the base location by RIE (Fig. 2a).  Then about 100-200
nm of p++ poly is deposited everywhere (Fig. 2b).  The thickness is
determined by the desired n-collector width.  p++ poly is reactive
ion etched everywhere, stopping on the first layer of poly.  Then the
base implant is performed.  The implant would go in only on the side
with no oxide (Fig 2c).  Then the oxide is etched everywhere.  The
first deposited poly acts as an etch stop on the isolation oxide.
After this step the remainder of the poly (first 50 nm deposited
poly) is reactive ion etched everywhere.  Then the nitride spacers
are put and n+ implants for the emitter and collector are done (Fig.
2d), and silicide is formed.  Instead of starting with the n-doped
substrate, one can start with p-doped substrate.  But, then, instead
of the p-ba...