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Method for Fabricating an Inverse T-Gate with Self Aligned Punch-Through Stopper for Sub-Half Micrometer CMOS Devices

IP.com Disclosure Number: IPCOM000109069D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Bronner, G: AUTHOR [+4]

Abstract

Disclosed in this article is a method to fabricate an inverse-T gate MOSFET device with self-aligned punch-through stop implant to suppress short-channel effect without significantly increasing junction capacitance for high performance applications. The inverse T-gate structure allows one to fabricate fully gate-drain overlapped devices for improved hot carrier immunity.

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Method for Fabricating an Inverse T-Gate with Self Aligned Punch-Through Stopper for Sub-Half Micrometer CMOS Devices

       Disclosed in this article is a method to fabricate an
inverse-T gate MOSFET device with self-aligned punch-through stop
implant to suppress short-channel effect without significantly
increasing junction capacitance for high performance applications.
The inverse T-gate structure allows one to fabricate fully gate-drain
overlapped devices for improved hot carrier immunity.

      The fabricating sequence is depicted below:
1.   Fabricate Shallow Trench Isolation (STI) and grow gate oxide.
2.   Deposit a thin layer of polysilicon (first poly), followed by
oxide/nitride films over the gate oxide.
3.   Apply photoresist and the gate mask to pattern the nitride/oxide
layer as shown in Fig. 1.
4.   Perform a Punch-Through Stop (PTS) implant through the 1st poly
into the silicon substrate.  This will be of the same type as the
substrate doping.
5.   Deposit second poly and planarize by Chemical-Mechanical
Polishing (CMP) using the nitride layer as a polish stop.
6.   Strip nitride and oxide to arrive at the structure shown in Fig.
2.
7.   Perform an LDD implant through the first poly, which is blocked
from the channel region by the second poly. The implant type is
opposite to the substrate doping.
8.   Form a sidewall around the second poly by oxidation, CVD nitride
deposition, and RIE.
9.   Etch the first poly using the sidewall-d...