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This article relates generally to integrated circuit construction and, more particularly, to a process of defining submicron features by a dry lithographic process.
English (United States)
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Dry Lithographic Process
This article relates generally to integrated circuit construction and, more
particularly, to a process of defining submicron features by a dry lithographic
The number of steps required for the usual wet lithographic process can be
decreased and improved edge definition and resolution of submicron features
can be achieved by using a two-layer dry process, as follows: 1. Polyimide is
deposited on a substrate surface by either the spin-on technique or vapor
deposition. Better uniformity, low defect density and good adhesion are obtained
with the latter. 2. A photosensitive compound is deposited over the polyimide by
vacuum sublimation. Suitable compounds are derivatives of O-
nitrobenzaldehyde, esterified phenol or diazoquinone. 3. The photosensitive
compounds are then masked and exposed to ultraviolet light to form the desired
patterns. 4. After mask removal, the exposed substrate surface is subjected to a
vaporized silylating agent such as hexamethyldisilazane (HMDS). Silylation
replaces the reactive hydrogens with a trimethylsilyl group. 5. The silylated
surface is next subjected to oxygen plasma that converts those areas that have
been exposed to ultraviolet light into silicon dioxide film. The film serves as a
barrier to subsequent etching procedures for the underlying organic layer.