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Method to Form Very Thin SOI Films

IP.com Disclosure Number: IPCOM000108924D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Davari, B: AUTHOR [+4]

Abstract

Disclosed is a method to form sub-micron thick silicon films on insulator (SOI). The film can be formed by bonding a silicon wafer with patterned etch (polishing) stops to another silicon wafer with an insulator over the surface. After the bonding, the excess silicon is etched (polished) away. The process ends at the stop and a thin uniform silicon film over the insulator can be obtained. (Image Omitted)

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Method to Form Very Thin SOI Films

       Disclosed is a method to form sub-micron thick silicon
films on insulator (SOI).  The film can be formed by bonding a
silicon wafer with patterned etch (polishing) stops to another
silicon wafer with an insulator over the surface.  After the bonding,
the excess silicon is etched (polished) away.  The process ends at
the stop and a thin uniform silicon film over the insulator can be
obtained.

                            (Image Omitted)

      There are many techniques to form very thin SOI films.  The
wafer bonding offers the best quality SOI material.  However, it is
very difficult to make sub-micron thick SOI films using this
technique, since the thickness control of the etch-back or
polish-back process is limited: Using the conventional polish or etch
back technique, any non-uniformity in wafer thickness results in
non-uniformity in SOI thickness.

      A method is described that will result in much better thickness
control.  The figure shows the formation of the etch (polish) stops
on the original wafer.  The etch (polish) stop can be a patterned
oxide or oxide/nitride composites (or layers).  For example,
patterned recessed oxides and oxide-filled shallow trenches are good
polish stop when polishing the silicon in chemical-mechanical
polishing process.  They are also good for etch back in a dry etch
tool, since the oxide surface provides a good etch end-point signal.
With the imb...