Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
2005-03-15
2005-03-15
Mcpherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S313000, C430S005000, C216S022000, C216S047000, C216S066000, C360S313000, C360S324000, C029S603010
Reexamination Certificate
active
06866987
ABSTRACT:
The invention teaches how to image and etch very narrow and isolated features without resorting to expensive OPC measures. Assist features are placed close to the main feature so that the local pattern density becomes semi-dense or dense and the pattern is imaged in a bilayer suitable for use in liftoff. The lower (easily etched) layer is then exposed to a suitable solvent so that the upper (etch resistant) layer is slowly undercut. Undercutting can be terminated as long as all the assist features have been lifted off. Although the original isolated feature will, in most cases, also have all of its lower layer removed, it does not lift off because, as a requirement of the process, at least one of its ends remains connected to an area of photoresist that is too wide to be fully undercut.
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Ackerman Stephen B.
Chacko-Davis Daborah
Headway Technologies Inc.
Mcpherson John A.
Saile George D.
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