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Reinforced Silicon Nitride Membranes

IP.com Disclosure Number: IPCOM000118656D
Original Publication Date: 1997-May-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Cordes, SA: AUTHOR [+2]

Abstract

Silicon Nitride membranes are useful for a wide variety of scientific applications. They have proven to be excellent substrates for x-ray and electron microscopy, both for microelectronic and biological specimens. Silicon nitride membranes have been used as substrates for micromechanical devices, x-ray lithography masks, x-ray zone plates, and also as windows on vacuum systems. The usefulness of the silicon nitride membranes is due to several properties: the membranes are extremely flat; chemically inert; high transparency to x-rays, electrons, and visible light; and easily fabricated using standard microelectronic fabrication processes. Although very useful, these membranes are very fragile due to the low Young's modulus, high tensile stress and thickness (typically 0.04 micrometers) of the silicon nitride film.

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Reinforced Silicon Nitride Membranes

      Silicon Nitride membranes are useful for a wide variety of
scientific applications.  They have proven to be excellent substrates
for x-ray and electron microscopy, both for microelectronic and
biological specimens.  Silicon nitride membranes have been used as
substrates for  micromechanical devices, x-ray lithography masks,
x-ray zone plates, and  also as windows on vacuum systems.  The
usefulness of the silicon nitride  membranes is due to several
properties: the membranes are extremely flat;  chemically inert; high
transparency to x-rays, electrons, and visible light; and easily
fabricated using standard microelectronic fabrication  processes.
Although very useful, these membranes are very fragile due to  the
low Young's modulus, high tensile stress and thickness (typically
0.04 micrometers) of the silicon nitride film.  The fragile nature of
the silicon nitride has limited the membrane size to approximately
1-2 square  millimeters.

      A technique is described which improves the mechanical strength
of the membranes and allows fabrication of the membranes with a
larger area (12 square millimeters) and durability.  In this
technique, a metal  grid is electroformed on the membrane.  The
dimensions of the grid can  be varied over a wide range to meet the
requirements of strength and transparency.

      The fabrication process uses a <100> orientation silicon wafer,
which is coated with a layer of silic...