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Removable High Temperature Ion Implant Mask

IP.com Disclosure Number: IPCOM000086425D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Carruthers, R: AUTHOR [+4]

Abstract

An ion implant mask which can withstand high temperatures without distortion and yet can be easily removed in a mild solvent after completion of implant, is prepared by the following process: 1. Spin on an adhesion promoter (if needed). 2. Spin on a 20% solution of aromatic polysulfone in NMP. It has been found that if ASTREL (tradename of polysulfone marketed by The Carborundum Co.) is selected, then a 1% solution of 90/10 methylmethacrylate/methacrylic acid copolymer in 2-methoxyethanol is useful as the adhesion promoter. 3. Cure (hotplate): 5 minutes at 80 degrees C. 10 minutes at 210 degrees C. 20 minutes at 300 degrees C. 4. Evaporate 1000 Angstroms Si. 5. Define pattern - using either standard photoresist techniques or E-beam lithography. 6.

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Removable High Temperature Ion Implant Mask

An ion implant mask which can withstand high temperatures without distortion and yet can be easily removed in a mild solvent after completion of implant, is prepared by the following process:
1. Spin on an adhesion promoter (if needed).
2. Spin on a 20% solution of aromatic polysulfone in NMP. It has

been found that if ASTREL (tradename of polysulfone marketed

by The Carborundum Co.) is selected, then a 1% solution

of 90/10 methylmethacrylate/methacrylic acid copolymer in

2-methoxyethanol is useful as the adhesion promoter.
3. Cure (hotplate): 5 minutes at 80 degrees C.

10 minutes at 210 degrees C.

20 minutes at 300 degrees C.
4. Evaporate 1000 Angstroms Si.
5. Define pattern - using either standard photoresist

techniques or E-beam lithography.
6. Reactive ion etch - in CF(4) to etch Si, then in 0(2) to etch

the polysulfone layer.
7. Chemical cleanup : 10 seconds in 7:1 buffered HF.
8. Ion implant.

The mask is removed in approximately 15 minutes or less using N- methylpyrrolidone at about 50 degrees C. An advantage of the above process is that the reactive ion etching produces mask apertures having essentially vertical walls, which provide sharper definition of the implanted area than would be the case if a photoresist mask having a tapered edge profile were used.

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