Browse Prior Art Database

High Transmission Membranes for Electron and X-Ray Imaging

IP.com Disclosure Number: IPCOM000107372D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Dana, SS: AUTHOR [+2]

Abstract

Disclosed is a fabrication process for membranes which are highly transparent to X-ray radiation, electrons and visible light.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 85% of the total text.

High Transmission Membranes for Electron and X-Ray Imaging

       Disclosed is a fabrication process for membranes which
are highly transparent to X-ray radiation, electrons and visible
light.

      The films are made using a Low Pressure Chemical Vapor
Deposition (LPCVD) system.  Films containing boron, nitrogen, and
hydrogen are deposited onto silicon substrates with the following
deposition parameters:
      gas flow rates of 16 cc/min of 5% B2H6 diluted in hydrogen
carrier gas and 10 cc/min ammonia NH3,
      a total pressure of 360 mTorr, and
      a deposition temperature of 400~C.

      The chemical composition of the films obtained in this manner
is B9N2H3 .

      Membranes as thin as 100 nm are formed when the silicon is
etched away from these films.

      The membranes have been found to be pinhole-free, with a
tensile stress of the order of 10 E8 dyne/cm2.  They are transparent
in the visible spectral region with an index of refraction of 2.2.

      Since the membrane contains very little nitrogen, the location
of the nitrogen in the specimen which is placed on top of the
membrane can be determined by comparing the X-ray transmission
through the sample on both sides of the nitrogen absorption peak.

      These membranes have also been used as substrates for TEM
imaging and electron-beam writing because they have lower electron
backscattering than comparable strength silicon or silicon nitride
films.  They have,...