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Browse Prior Art Database

Metal Deposition Process for Improved Step Coverage

IP.com Disclosure Number: IPCOM000047525D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Dreves, RF: AUTHOR [+2]

Abstract

A cold evaporation process is provided which improves step coverage at contacts to a semiconductor substrate by filling in and bridging discontinuities in aluminum generated at steep-walled topography location. This process enables improved edge coverage obtained with sputtering to be compatible with known lift-off techniques. As indicated in Fig. 1, a thin layer 10 of silicon dioxide is grown on a silicon substrate 12, and a thin layer 14 of silicon nitride is deposited over layer 10. By using known etching techniques, an opening 16 is provided in layers 10 and 14 with layer 10 being undercut with respect to layer 14, as illustrated in Fig. 1. A layer 18 of photoresist is deposited over layer 14 with an opening 20 formed therein over the opening 16 formed in layers 10 and 14.

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Metal Deposition Process for Improved Step Coverage

A cold evaporation process is provided which improves step coverage at contacts to a semiconductor substrate by filling in and bridging discontinuities in aluminum generated at steep-walled topography location. This process enables improved edge coverage obtained with sputtering to be compatible with known lift-off techniques. As indicated in Fig. 1, a thin layer 10 of silicon dioxide is grown on a silicon substrate 12, and a thin layer 14 of silicon nitride is deposited over layer 10. By using known etching techniques, an opening 16 is provided in layers 10 and 14 with layer 10 being undercut with respect to layer 14, as illustrated in Fig. 1.

A layer 18 of photoresist is deposited over layer 14 with an opening 20 formed therein over the opening 16 formed in layers 10 and 14. Opening 20 is made in a known manner so as to have a narrower width at its upper portion than at its lower portion. A contact defined by the opening 16 is then formed on the surface of substrate 12 by depositing sequentially over photoresist layer 18 and into opening 20 a first layer 22 of aluminum, a thin layer 24 of copper, a second layer 26 of aluminum and a thin layer 28 of silicon. The aluminum and silicon layers 22, 26 and 28 are evaporated at a normal angle of incidence for lift-off compatibility. The copper is sputter deposited, i.e., at random angles of incidence, so that the copper layer 24 forms copper layer segment 24' over the...