Two layer resist system

DETAILED DESCRIPTION I claim: 1.
A method for forming a composite layer of resist materials comprising: providing first and second resist materials, each resist material being a sensitized organic polymer capable of forming a patterned resist mask to protect the underlying portions of a substrate; saturating said second resist material with a dilutant which does not dissolve said first resist material; applying said first resist material atop said substrate; and applying said saturated resist material atop said first material, thereby forming said composite layer.
2.
A method as in claim 1 wherein said resists include a phenol formaldehyde resin.
3.
A method as in claim 2 wherein said resists include a diazo oxide sensitizer.
4.
A method as in claim 3 wherein said resists include cellosolve solvent.
5.
A method as in claim 4 wherein said dilutant is selected from the group consisting of xylene, toluene, chlorobenzene and freon.
6.
A method as in claim 1 wherein said resists include poly-cis-isoprene cyclized rubber.
7.
A method as in claim 6 wherein said resists include xylene solvent.
8.
A method as in claim 1 further comprising: providing a third resist material which is a sensitized organic polymer; saturating said third resist material with said dilutant; applying said third saturated resist material atop said second resist material.




Description:
BACKGROUND OF THE INVENTION Field of the Invention This invention relates generally to resist layer structures and more particularly to high sensitivity resist layers useful in lithographic processes.
Optical or electron beam lithography is still used as the main tool in micro-circuit fabrication.
It is expected to continue into the near future.
The additive metallization technique known as "lift-off" was developed with the advent of electron beam lithography in the late 1960's.
It provides the metallization after the exposure and development of the resist.
Basically, the lift-off technique utilizes the fact that electron scattering in the resist and back scattering from the substrate creates a tear-shaped energy absorption profile in the resist, which results in an undercut profile after resist development