Browse Prior Art Database

Polyimid Free Silicon X-Ray Mask Substrate

IP.com Disclosure Number: IPCOM000120031D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Babich, I: AUTHOR [+3]

Abstract

A silicon X-ray mask substrate with better absorber adhesion, improved X-ray transmission, and higher dimensional stability is described.

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

Polyimid Free Silicon X-Ray Mask Substrate

      A silicon X-ray mask substrate with better absorber
adhesion, improved X-ray transmission, and higher dimensional
stability is described.

      In the boron-doped silicon X-ray masks a 1.5-2-mm-thick
polyimid layer is used as a transparent carrier for aligning marks.
Swelling of the polyimid layer and moderate stability during wet
processes prevent proper cleaning (Huang cleaning) of the mask
substrate and worsen the adhesion of the absorber.  This creates a
potential source of metal particles and organic debris.  Gold and
chromium particles and organic chunks were found on the wafers
exposed in the X-ray stepper.  During development, most of the
particles are washed away, but their presence on the exposed wafers
poses a threat of printing defects and occasional contamination.

      As the recent investigations show (*), the polyimid film does
not contribute to the strength of the silicon membrane.  Actually,
the polyimid film tends to loose dimensional stability with the
accumulated dose of ionization radiation and causes distortions of
the absorber pattern.  In addition, a 2-mm-thick polyimid layer
absorbs about 20% of the X-rays passing through it, thus increasing
the exposures.

      The purpose of this disclosure is to describe a new X-ray mask
substrate free from the above mentioned above drawbacks.

      This is achieved by forming an inorganic transparent film in
the aligning windows of the mask.  The formation of the aligning
marks carrier film can be performed on different sta...