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Browse Prior Art Database

Sputter-Resistant Mask Structure and Process

IP.com Disclosure Number: IPCOM000101725D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 86K

Publishing Venue

IBM

Related People

Cronin, J: AUTHOR [+5]

Abstract

Process techniques are shown for fabricating sputter-resistant masks resulting in superior post etch profiles and tolerances in the manufacture of semiconductors.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Sputter-Resistant Mask Structure and Process

       Process techniques are shown for fabricating
sputter-resistant masks resulting in superior post etch profiles and
tolerances in the manufacture of semiconductors.

      Reactive ion etching (RIE) for high density DRAM products
requires attainment of both high directionality and a high etch rate
ratio (ERR) between the etch mask and substrate. The ERR is typically
measured by comparing the etch rate of the substrate with a large
isolated area of the mask. This ERR is misleading since it does not
take into account the effect of preferential sputtering of the mask
at the corners. This erosion results in a faceting of the mask that
typically propagates 2-3X faster than the blanket removal rate of a
masking film. Yield loss can result from mask breakthrough and the
lack of dimensional control due to corner sputtering. A
facet-resistant mask can be fabricated by employing materials with
both a low sputter yield and high sputter threshold. Materials that
fit these criteria include Al2O3, TiN, and CoSi2 . However, some of
these materials are chemically etch resistant and difficult to define
with common RIE chemistries. Methods to employ these materials that
result in maximum sputter resistance during RIE patterning are
described.

      A "U-mask" employing both a sputter-resistant film and a
chemically resistant film is shown in Fig. 1. Examples of films that
can be used in this application include the following:
      A = SiO2, Si3N4, Poly-Si.
      B = Al2O3, TiN, CoSix .
      C = Poly-Si, SiO2, Si3N4 . (The choice of films A and C depends
upon the etch application.)

      A method for fabricating a "U-mask" follows:
   1. Image a negative mask of the desired photo pattern
      int...