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Self-Isolated Tapered Submicron Contact Hole With Variable Double Isolator Thickness

IP.com Disclosure Number: IPCOM000099524D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 70K

Publishing Venue

IBM

Related People

Koblinger, O: AUTHOR

Abstract

The invention describes how, starting with a steep contact hole in a first isolator, a second isolator is deposited without a mask and how the second isolator is dry-etched while its angle is adjusted. The second isolator is retained as a liner on the inside of the contact hole in the first isolator.

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This is the abbreviated version, containing approximately 60% of the total text.

Self-Isolated Tapered Submicron Contact Hole With Variable Double Isolator Thickness

       The invention describes how, starting with a steep contact
hole in a first isolator, a second isolator is deposited without a
mask and how the second isolator is dry-etched while its angle is
adjusted.  The second isolator is retained as a liner on the inside
of the contact hole in the first isolator.

      Contact holes are imaged in photoresist, using optical exposure
devices as are currently available.  The minimum spacing of the
contact hole from the polysilicon and recessed oxide (ROX) may be
zero.  In critical cases, the contact hole may impinge slightly upon
the polysilicon, so that the space contact holes normally require is
greatly reduced.  Then, the holes are steep-etched, which can be done
without difficulty from a process standpoint (Figs. 1A, 2A).

      Subsequently, an oxide layer (isolator 2) is deposited covering
as a liner isolator 1, into which the contact holes have been etched,
i.e., the side walls and the base of the contact walls (Figs. 1B,
2B).

      If contact holes of only one size are used or if a maximum size
is not exceeded, the oxide layer on the side walls and the base of
the contact holes will be much thinner than on the surface of
isolator 1 as a result of the proximity effect.

      The applied oxide is reduced by being etched to a thickness at
which the contact holes at the base are reliably opened (Figs. 1C,
2C).

   ...