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Silylation Method to Enhance the Contrast of Reactive Ion Etched Images

IP.com Disclosure Number: IPCOM000035286D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 66K

Publishing Venue

IBM

Related People

Bruce, JA: AUTHOR [+2]

Abstract

A resist silylation method is described which allows high contrast dry develop imaging in thin positive or negative photoresist layers.

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Silylation Method to Enhance the Contrast of Reactive Ion Etched Images

A resist silylation method is described which allows high contrast dry develop imaging in thin positive or negative photoresist layers.

Silylation of photoresist (the replacement of an active hydrogen group, e.g., alcohols, phenols, amines, etc. with a silicon atom), utilizing a silylating agent as hexamethylcyclotrisilazane (HMCTS), offers a method for creating oxygen- resistant reactive ion etch (RIE) barriers. By introducing silicon into the resist with HMCTS, linkages are formed which are further converted into SiO2 during oxygen etch, producing a large etch variation between the silylated and unsilylated material.

A more durable portable conformal mask (PCM) structure for advanced semiconductor products can be attained through higher ratios of silicon in the resist pattern. When incorporated into a thin resist layer, increased silicon will increase mask durability and thus contrast.

When HMCTS reacts with exposed photoactive compounds, a labile silylamide is formed which hydrolyzes in moist air to form an acid. This acid may further react with HMCTS to increase the amount of silicon in the exposed photoresist. This suggests an unconventional method for producing a high contrast resist mask with or without image development using wet methods. To increase the amount of silicon in exposed photoresist, repeated silylation (a second or third silylation reaction) can be achieved by preconditioning the silylated photoresist with moist air, or a solution containing water, followed by a silylation process to re-silylate the exposed photoresist.

Using a wet develop and conventional silylation, this technique will enhance image contrast by allowing a second or third silylation reaction. A totally dry etch method is also shown using a film of radiation-sensitive resist. A comparison of wet...