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Portable Conformable Mask Process With an Improved Deep UV Resist Underlayer

IP.com Disclosure Number: IPCOM000042744D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Kaufman, FB: AUTHOR [+2]

Abstract

A process has been previously proposed which employs PMMA (polymethylmethacrylate) as an underlayer with a top imaging layer of a positive working diazoquinone novolak resist. After top layer patterning, the imaged layer can act as a deep UV (ultraviolet) mask due to its opacity to deep ultraviolet (DUV) radiation. A subsequent DUV flood exposure and development operation transfers the pattern from the top imaging layer to the bottom thick planarizing layer which is sensitive to DUV radiation. Since the top masking layer is in intimate contact with the underlying DUV resist, modulation of the flood exposure radiation is minimized. Although this configuration offers significant performance advantages such as resolution, control over topography, etc.

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Portable Conformable Mask Process With an Improved Deep UV Resist Underlayer

A process has been previously proposed which employs PMMA (polymethylmethacrylate) as an underlayer with a top imaging layer of a positive working diazoquinone novolak resist. After top layer patterning, the imaged layer can act as a deep UV (ultraviolet) mask due to its opacity to deep ultraviolet (DUV) radiation. A subsequent DUV flood exposure and development operation transfers the pattern from the top imaging layer to the bottom thick planarizing layer which is sensitive to DUV radiation. Since the top masking layer is in intimate contact with the underlying DUV resist, modulation of the flood exposure radiation is minimized. Although this configuration offers significant performance advantages such as resolution, control over topography, etc., it suffers from separate drawbacks related to the use of PMMA underlayer - poor thermal stability, poor plasma and RIE resistance, and low DUV sensitivity. An additional problem is that PMMA is somewhat soluble in the classes of solvents which can be used to cast diazoquinone/novalak resist films. This results in mixing between the top and bottom layers during the coating steps. The extent of the mixing affects the performance of the masking and, in general, is difficult to eliminate. It has been found that these problems can be resolved by the use of chloro- methylated polystyrene (CMS) as the planarizing underlayer in a mask configuration....