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Method for Making Device Trench Isolation and/or Contacts

IP.com Disclosure Number: IPCOM000120290D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR [+3]

Abstract

By making trenches for isolation and/or contacts after high temperature processing is complete, stress-induced defects adjacent to the trenches are minimized. Deep trench or "reach through" connections to the substrate are also made at this stage of processing, thereby minimizing resistance in device-to- substrate current paths and maximizing device density.

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Method for Making Device Trench Isolation and/or Contacts

      By making trenches for isolation and/or contacts after high
temperature processing is complete, stress-induced defects adjacent
to the trenches are minimized.  Deep trench or "reach through"
connections to the substrate are also made at this stage of
processing, thereby minimizing resistance in device-to- substrate
current paths and maximizing device density.

      Referring to the figure, conventional processing is used to
form N-well 2, shallow trench isolation regions 4, and diffusions 6
in silicon substrate 8.  Conventional processing is used to form gate
insulation 10 and gate conductor 12, then to deposit, reflow, and
planarize glass layer 14.  Deep trench 16 is then etched through
glass 14, and N-well 2.  Implantation of an appropriate impurity may
be performed next to form diffusion region 18 to minimize contact
resistance.  Insulation 20 may be grown or deposited and a clean-out
anisotropic etch used to expose diffusion 18 before or after the
implantation.  Metal, e.g., tungsten, is conformally deposited and
planarized to fill trench 16, thus bringing a low resistance contact
from substrate 8 through N-well 2 to the surface of glass 14 in close
proximity to device structure 12, 6, and 4.

      Device isolation trenches and contacts to other device
structures, e.g., N-well 2, diffusions 6, and gate conductor 12, may
also be beneficially performed in a similar manner at this late stag...