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Browse Prior Art Database

Lift-off Processes with Improved Step Coverage

IP.com Disclosure Number: IPCOM000044695D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Dinklage, JB: AUTHOR [+2]

Abstract

A technique for improving the step coverage of metal lift-off processes. It involves using a blanket metal film on the wafer before the formation of the photoresist mask. This provides a good base film uniformity covering all topography and establishing a surface for nucleation of the subsequent evaporated metal.

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Lift-off Processes with Improved Step Coverage

A technique for improving the step coverage of metal lift-off processes. It involves using a blanket metal film on the wafer before the formation of the photoresist mask. This provides a good base film uniformity covering all topography and establishing a surface for nucleation of the subsequent evaporated metal.

Existing lift-off processes require that metal be deposited to a near normal incidence evaporation in order to keep metal from coating the walls of the resist lift-off structure. This requirement makes the coverage of steep topographies difficult, increasing the risks for cracks in overlying metal traces.

The technique disclosed herein involves the deposition of a metal film having a thickness of 0.1 to 0.2 mm to act as a nucleating layer for improving the quality of the subsequently evaporated film. The later film will adhere to the earlier metal film much better and will provide an improved step coverage.

After the top metal film is evaporated and lifted-off, then the patterned film can serve as an etch mask, while removing the unwanted metal of the lower (first) layer from the unpatterned areas. This metal removing can be accomplished through wet dip etching, or through plasma etching or reactive ion etching depending on the amount of undercut that can be tolerated.

Disclosed anonymously

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