Browse Prior Art Database

Partially Recessed FET

IP.com Disclosure Number: IPCOM000108243D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Bracchitta, JA: AUTHOR [+2]

Abstract

A process is described for fabricating partially recessed FET (PARFET) devices with high-conductivity gates. A uniform silicide layer over the wafer is etched to form a trough for each FET channel. Gate oxide is grown at the bottom of the trough, and layers of polysilicon and metal are deposited to form the FET gates. Shallow trenches isolate adjacent devices. Layers of oxide and nitride are added for planarization.

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Partially Recessed FET

       A process is described for fabricating partially recessed
FET (PARFET) devices with high-conductivity gates. A uniform silicide
layer over the wafer is etched to form a trough for each FET channel.
Gate oxide is grown at the bottom of the trough, and layers of
polysilicon and metal are deposited to form the FET gates. Shallow
trenches isolate adjacent devices. Layers of oxide and nitride are
added for planarization.

      The PARFET process consists of the following steps:
      1.   A silicide layer is deposited over the entire wafer
(optional).
      2.   Sources and drains are implanted through the silicide.
      3.   FET devices are defined by shallow trench isolation.
      4.   A blanket oxide-1 layer is deposited and planarized.
      5.   A blanket nitride layer is deposited.
      6.   A gate region is etched through the nitride, oxide-1 and
silicide layers and into the substrate to form a recessed trough.
      7.   Nitride is deposited and etched to form sidewall spacers
in the recessed trough.
      8.   Gate oxide is grown on the bottom of the trough. At this
point in the process, a typical FET looks like Fig. 1.
      9.   Polysilicon is deposited on top of the gate oxide.
      10.  Gate metal is deposited on top of the polysilicon layer.
      11.  The gate conductor is recessed and oxide-2 is deposited
over the recessed area to form a planar s...