Browse Prior Art Database

Lift Off Trench Process for Multilevel Metallurgy

IP.com Disclosure Number: IPCOM000050109D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Bross, A: AUTHOR [+3]

Abstract

Multilevel metal insulator structures (three or more levels of metal) for semiconductor device fabrication must have as little topography as possible, especially if small dimensions are to be maintained on all levels. This process enables the making of a planar multilevel structure using truly dual dielectric insulators.

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Lift Off Trench Process for Multilevel Metallurgy

Multilevel metal insulator structures (three or more levels of metal) for semiconductor device fabrication must have as little topography as possible, especially if small dimensions are to be maintained on all levels. This process enables the making of a planar multilevel structure using truly dual dielectric insulators.

The first level of metal is deposited by the conventional lift off technique and planarized with quartz lift off or other means. This process allows the continuation of this multilevel structure in a planar manner by using the following repetitive steps:

1. Masking: Polyimide is deposited and cured on the substrate to a thickness approximately equal to the intended final metal thickness of this layer. A thin layer of SiN(x) is deposited over the polyimide by conventional plasma CVD (chemical vapor deposition) means. Next, a thin layer of polysulfone is deposited on the SiN(x) for the soluble lift off layer. Finally, a thick photoresist is deposited, exposed, and developed to the desired pattern. The photomask must have a profile angle between 80 and 90 degrees from the horizontal. Its thickness must exceed the combined thicknesses of polyimide, SiN(x); and polysulfone.

2. Etching: The whole structure can be etched using CF(4) in a RIE (reactive ion etching) mode, to within a short distance of the metal interface, to transfer the photoresist angle into the underlying layers. The final thin layer of...