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Anti Interference and Antireflection Coatings for Chromium Masks

IP.com Disclosure Number: IPCOM000075190D
Original Publication Date: 1971-Aug-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 55K

Publishing Venue

IBM

Related People

Sadagopan, V: AUTHOR

Abstract

ANTI-INTERFERENCE COATING.

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Anti Interference and Antireflection Coatings for Chromium Masks

ANTI-INTERFERENCE COATING.

In the photolithographic processing of silicon wafers coated with photoresist as in Fig. 1A, the high-refractive index of silicon causes a strong standing wave to be produced in the SiO(2)-photoresist layer. The latter standing wave interferes with the projected wave and causes poor images and uneven exposure of the resist layer. Other adverse effects such as haloing also originate from the presence of the standing wave. These problems are eliminated by interposing an absorption layer, as shown in Fig. 1B, at the SiO(2) resist interface which absorbs the ultraviolet light. This absorption layer comprises a GaFeO(3) film of approximately 3000 Angstroms thick deposited on a SiO(2) surface by sputtering techniques. The formed GaFeO(3) is compatible with both SiO(2) and the resist and is also readily etchable with etchants used for SiO(2). In a 3000 Angstroms thickness, the GaFeO(3) layer is able to absorb the ultraviolet light and prevent the formation of the standing wave. ANTIREFLECTION COATINGS.

Antireflection coatings are provided against ultraviolet radiation to improve workability with chromium masks. Such coatings cut down poor pattern formation.

One of the serious problems encountered in chromium mask technology is the large amount of light reflected back inside of the mask, as shown in Fig. 2A. Currently, this detrimental effect is minimized by either softer or dark field lighting. An antireflection coating that is compatible with chromium is recognized to...