Browse Prior Art Database

Metal Lift-Off Process Extension to Submicron Dimensions

IP.com Disclosure Number: IPCOM000040653D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Bergendahl, AS: AUTHOR [+4]

Abstract

Manipulation and control of deep ultraviolet (DUV) photoresist bake time and temperature provides a suitable process window and image for metal lift-off applications in the submicron range. The lift-off of evaporated metal patterns from integrated circuits has been an important aspect of semiconductor chip fabrication for many manufacturers. The ability to manipulate and control the resist image profiles are critical factors in a submicron metal lift-off process. An overview of this process is shown in the figure. A resist image with negative slopes is formed on a wafer followed by a blanket deposit of metal. After metal deposition, resist is rinsed off the wafer, and metal is removed from selected areas leaving a defined circuit pattern on the wafer.

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Metal Lift-Off Process Extension to Submicron Dimensions

Manipulation and control of deep ultraviolet (DUV) photoresist bake time and temperature provides a suitable process window and image for metal lift-off applications in the submicron range. The lift-off of evaporated metal patterns from integrated circuits has been an important aspect of semiconductor chip fabrication for many manufacturers. The ability to manipulate and control the resist image profiles are critical factors in a submicron metal lift-off process. An overview of this process is shown in the figure. A resist image with negative slopes is formed on a wafer followed by a blanket deposit of metal. After metal deposition, resist is rinsed off the wafer, and metal is removed from selected areas leaving a defined circuit pattern on the wafer. The extension of this technique to submicron lithography dimensions is limited by the resolution of middle ultraviolet resist used to provide a lift-off structure. By decreasing the exposure light wavelength of a photoresist, the lithographic image resolution can be increased. A deep ultraviolet resist has been developed which provides improved resolution but differs from most DUV resists in that it requires a post exposure bake cycle to define the image. After the bake cycle, the unexposed resist can be dissolved in an organic solvent to produce a negative tone pattern on a wafer. The shape of the image due to undercutting can be altered by controlling the ti...