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Browse Prior Art Database

Lift Off Process

IP.com Disclosure Number: IPCOM000085365D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Smyth, MJ: AUTHOR

Abstract

The lift-off process is a widely used method to generate metallization patterns on wafer surfaces. A pattern is first defined on the resist-coated surface followed by metal deposition over the entire surface. By immersion in a suitable solvent, usually in an ultrasonic bath, the metal lifts off from areas of the wafer surface coated with resist. The metal pattern remains in the uncoated areas. High resolution patterns (~ 1 Micron spacing) are extremely difficult to define when the wafers are immersed vertically in the solvent in the ultrasonic bath, requiring extensive immersion time and continuous inspection.

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Lift Off Process

The lift-off process is a widely used method to generate metallization patterns on wafer surfaces. A pattern is first defined on the resist-coated surface followed by metal deposition over the entire surface. By immersion in a suitable solvent, usually in an ultrasonic bath, the metal lifts off from areas of the wafer surface coated with resist. The metal pattern remains in the uncoated areas. High resolution patterns (~ 1 Micron spacing) are extremely difficult to define when the wafers are immersed vertically in the solvent in the ultrasonic bath, requiring extensive immersion time and continuous inspection.

The method can be substantially improved by immersing each wafer (front surface down) in the ultrasonic tank midway in the solvent facing the bottom of the tank and parallel to it. This technique has worked very successfully with Al patterns ~ 1 Micron wide, requiring 2 minutes immersion as opposed to 30 minutes for the conventional vertical immersion approach. In addition to the savings in time, this procedure has been found to result in a substantially higher yield.

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