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Negative Photoresists From Polymers Containing Carboxylic Acid Side chains

IP.com Disclosure Number: IPCOM000089787D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Pacansky, J: AUTHOR

Abstract

Negative photoresists are produced when polymers with carboxylic acid groups in their side chains (or as the side chain) are irradiated with ultraviolet (UV) light in the presence of a photoactive compound with polyfunctional diazo-oxide groups in vacuum.

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Negative Photoresists From Polymers Containing Carboxylic Acid Side chains

Negative photoresists are produced when polymers with carboxylic acid groups in their side chains (or as the side chain) are irradiated with ultraviolet (UV) light in the presence of a photoactive compound with polyfunctional diazo- oxide groups in vacuum.

For example, a mixture of polyacrylic acid and a defunction diazo-oxide was cast from an organic solvent onto a CsI substrate. Upon UV irradiation at T = 77K, the infrared spectrum showed that the diazo-oxide was converted to a ketene. Upon warm-up to room temperature, the ketene and carboxylic OH from the polymer disappeared with the formation of new carboxyl bands at 1750 and 1720 cm/-1/. These are characteristic of the expected anhydride product, and is conclusive proof that an anhydride is being formed and cross-linking the polymer.

The same mixture was cast onto a silicon wafer and irradiated through a mask in vacuum (thus cross-linking the polymer). Subsequently, the mask was removed and a flood exposure of the wafer in air was performed to convert the photoactive material in the vacuum nonirradiated areas to carboxylic acid. The wafer was then placed in an aqueous base developer (pH = 9). A negative image was formed only in those areas irradiated in vacuum.

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