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High Temperature Lift-Off Stencil

IP.com Disclosure Number: IPCOM000036020D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

Deposition of refractory metals, single crystal or epitaxial films, superconducting materials with high transition temperatures, etc., usually requires elevated substrate temperatures to ensure good quality films. Typical substrate temperatures can range from 400 to 600oC. Ordinary photoresist stencils will not survive these elevated temperatures, thus are not able to provide a lift-off stencil. The alternative way of patterning pre-deposited films with photoresist (whether by wet or dry processes) can be a cause of contamination. A technique is described for providing a patterned lift-off stencil that allows deposition of films at high temperatures. The technique utilizes a spin-on glass* which yields high quality silicon dioxide- like films upon spin-on application and subsequent curing at low temperatures (400oC).

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High Temperature Lift-Off Stencil

Deposition of refractory metals, single crystal or epitaxial films, superconducting materials with high transition temperatures, etc., usually requires elevated substrate temperatures to ensure good quality films. Typical substrate temperatures can range from 400 to 600oC. Ordinary photoresist stencils will not survive these elevated temperatures, thus are not able to provide a lift-off stencil. The alternative way of patterning pre-deposited films with photoresist (whether by wet or dry processes) can be a cause of contamination. A technique is described for providing a patterned lift-off stencil that allows deposition of films at high temperatures. The technique utilizes a spin-on glass* which yields high quality silicon dioxide- like films upon spin-on application and subsequent curing at low temperatures (400oC). The cured films are of excellent mechanical integrity, are highly amorphous, crack-free, have a very low density of pinholes and particulates and are capable of withstanding temperatures as high as 900 C.

The process steps are shown in Figs. 1(a) - 1(e). In Fig. 1a, the spin-on glass 10 is coated onto a substrate 12 (such as MgO) at a spin speed of 2000 rpm and prebaked to drive off solvents. The film/

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substrate is then cured at 400oC for 1 hour in an ambient of air or nitrogen- oxygen mixture. This cure step will yield a glass film thickness of approximately
0.3 micron. Photoresist layer 14 (Fig. 1b)...