Browse Prior Art Database

Lift Off Mask Structure

IP.com Disclosure Number: IPCOM000084245D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Fredericks, EC: AUTHOR [+2]

Abstract

A multilayer metal lift-off structure employs a layer of a methyl methacrylate/methacrylic acid copolymer, to provide adhesion of the structure to a silicon oxide surface. The layer provides exceptional adhesion and high-temperature processing capabilities.

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Lift Off Mask Structure

A multilayer metal lift-off structure employs a layer of a methyl methacrylate/methacrylic acid copolymer, to provide adhesion of the structure to a silicon oxide surface. The layer provides exceptional adhesion and high- temperature processing capabilities.

As shown in Fig. 1, silicon wafer substrate 1 has a silicon dioxide layer 2 on its surface. Onto the silicon oxide layer 2 is coated a layer 3 of a 90/10%, by weight, methyl methacrylate/methacrylic acid copolymer. On top of the copolymer 3 is coated a methylsiloxane resin barrier layer 4. On top of the resin layer 4 is coated a radiation sensitive resist layer 5, which can be patterned either by actinic or high-energy radiation. The resist layer 5 is, for example, a polymethyl methacrylate polymer or a phenol-formaldehyde novolak resin based resist containing a diazo ketone sensitizer.

As shown in Fig. 2, silicon substrate 11 having a thermal oxide layer 12 on its surface is coated with a thin-adhesive layer 13 of methyl methacrylate/methacrylic acid copolymer, followed by resin layer 14 comprising basically an aromatic polysulfone. Methylsiloxane resin layer 15 is then coated on the polysulfone layer 14 followed by a radiation patternable resist layer 10, as shown in Fig. 1.

The resist layers 5 or 10 are subjected to radiation and developed to provide a patterned relief image with the openings 6 or 16, corresponding to where it is desired to evaporate metal on the silicon substrate....