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Dry Etch Rate Control of Photoresist by E-Beam Exposure

IP.com Disclosure Number: IPCOM000051465D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Forster, T: AUTHOR

Abstract

It has been found that etch properties of positive E-beam photoresist are altered when it is exposed to electron irradiation. This effect can be used (a) for resist pattern reversal and (b) to obtain steep edges in plasma-etched profiles.

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Dry Etch Rate Control of Photoresist by E-Beam Exposure

It has been found that etch properties of positive E-beam photoresist are altered when it is exposed to electron irradiation. This effect can be used (a) for resist pattern reversal and (b) to obtain steep edges in plasma-etched profiles.

Experiments have shown that the removal rate of E-beam resist in a CF(4) RF-plasma at 500 mtorr and a power density of 0.4 W/cm/2/ decreases from 80 Angstroms/min to 20 Angstroms/min when an electron dose of 1x10/-3/ coulomb/cm/2/ is applied; i.e., the resistance against dry etching is a function of the electron irradiation.

This effect can be used to reverse the resist pattern, also referred to as image reversal, which, for a low coverage pattern, yields a substantial reduction in E-beam writing time. Exposing a pattern in E-beam resist with a high E-beam dose, and etching this resist layer in a CF(4) RF-plasma, results in a reversed resist pattern as compared to a conventional exposure and developing procedure where the exposed resist is removed.

The described effect can also be employed to control etched pattern profiles when a photoresist mask is used in a plasma etching step. During etching, the resist removal rate determines the steepness of the profile edge. Lower removal rates, obtained by a flood E-beam exposure of the resist mask, result in steeper edges.

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