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SIR Compatible E-Beam Exposure Process with Reduced Resist Thinning

IP.com Disclosure Number: IPCOM000037486D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Barry, JA: AUTHOR [+2]

Abstract

This article concerns a simplified process for the controlled removal of an aluminum/copper (A1/Cu) conductive discharge layer from above a layer of or any others imaging resist, both layers are initially required to be present in the MLR (multilayer resist) used in the E-beam (electron beam) lithographic processing of semiconductor devices. Excessive thinning of the imaging layer must be prevented during removal of the conductive discharge layer otherwise the MLR would be rendered unusable.

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SIR Compatible E-Beam Exposure Process with Reduced Resist Thinning

This article concerns a simplified process for the controlled removal of an aluminum/copper (A1/Cu) conductive discharge layer from above a layer of or any others imaging resist, both layers are initially required to be present in the MLR (multilayer resist) used in the E-beam (electron beam) lithographic processing of semiconductor devices. Excessive thinning of the imaging layer must be prevented during removal of the conductive discharge layer otherwise the MLR would be rendered unusable.

Fig. 1 shows the lift-off structure as presently constituted. The substrate [1] is covered by an underlayer [2] on top of which is a layer of imaging resist [3] and an A1/Cu discharge layer [4]. The discharge layer must be removed prior to a later bake cycle of the imaging resist. Following the bake cycle the resist is developed in a hydroxide etch solution. The bake is necessary, following exposure, to enhance the contrast by reducing the dissolution rate in the developer of the unexposed (or partially exposed) resist. If the resist is baked with the A1/Cu and a) sets up mechanical stresses in the layer, and b) the A1/Cu appears to interact with the top resist -- the net result is increased solubility in the developer of the unexposed resist and reduced contrast, as well as uneven development caused by the penetration of the developer through the wrinkled discharge layers.

The E-beam exposure process here di...