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Improved Process for Fabrication of Conically-Undercut Dielectric Stencil Masks

IP.com Disclosure Number: IPCOM000105954D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Cordes, SA: AUTHOR [+2]

Abstract

Disclosed are two processes for the fabrication of conically undercut dielectric stencil masks. These masks consist of a patterned silicon membrane which is then coated with a dielectric film. The processes disclosed below provide the necessary controls for the thickness of the membrane and the shape of the patterns.

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Improved Process for Fabrication of Conically-Undercut Dielectric Stencil Masks

      Disclosed are two processes for the fabrication of conically
undercut dielectric stencil masks.  These masks consist of a
patterned silicon membrane which is then coated with a dielectric
film.  The processes disclosed below provide the necessary controls
for the thickness of the membrane and the shape of the patterns.

      Fabrication process #1:  In this process, a silicon wafer,
(100) orientation is heavily doped with boron to a depth of 2-5
micrometers.  This layer acts as an etch stop and the boron
concentration must exceed  5 x 10E19 atoms per cubic centimeter.
Next, a layer of epitaxial silicon is grown on the doped surface.
The thickness of this layer determines the thickness of the final
membrane.  The surfaces of the wafer are oxidized.  An opening which
determines the size of the overall membrane is patterned into the
oxide and the wafer is etched in an anisotropic silicon etchant [1,
2].  The back surface of the resulting membrane is then patterned to
form the desired openings in the membrane.  The formation of these
openings from the back side of the membrane results in a conical
undercut shape.

      Fabrication process #2:  This process uses the same steps as
process #1 through the growth of the epitaxial silicon layer.  A high
concentration boron layer is formed on both sides of the silicon
wafer.  The desired membrane opening pattern is then form...