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Directional Etch Mask in Single Layer Resist

IP.com Disclosure Number: IPCOM000047310D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Gillespie, SJ: AUTHOR

Abstract

This article describes a process for making a resist mask using a single layer of positive resist that is suitable for directional etching of micron and submicron lines. The resist is surface hardened and then E-beam exposed at a sufficiently high dose to completely undercut the resist lines. The resulting resist lines may or may not be fully suspended depending on their width and the dose used. In prior-art processes, single layer resists have been used to perform like double layer resists through a surface hardening technique which resulted in a different solubility in the developer between the upper layer and the remainder of the material. This provided undercut profiles which have been used, for example, in metal lift-off.

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Directional Etch Mask in Single Layer Resist

This article describes a process for making a resist mask using a single layer of positive resist that is suitable for directional etching of micron and submicron lines. The resist is surface hardened and then E-beam exposed at a sufficiently high dose to completely undercut the resist lines. The resulting resist lines may or may not be fully suspended depending on their width and the dose used. In prior-art processes, single layer resists have been used to perform like double layer resists through a surface hardening technique which resulted in a different solubility in the developer between the upper layer and the remainder of the material. This provided undercut profiles which have been used, for example, in metal lift-off. However, among the limitations of these processes is what is often referred to as "resist foot", which is resist protrusions on the surface of the substrate that cause etched line quality degradations. The process described in this article eliminates this and the other limitations of the prior processes through the use of the top edges of the hardened surface of the resist as a mask for the directional etching of the remaining portion of the resist layer. This is accomplished without the extra costs and complexities associated with the double layer resist processes. For example, the surface hardening of the resist may be achieved by a 20-second dip in 0.23 N KOH developer. This is followed by a r...