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In-Situ Resist Hardening for Anisotropic Etching in High Pressure Plasma Reactors

IP.com Disclosure Number: IPCOM000035318D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Holland, S: AUTHOR

Abstract

By adding certain agents to a reactive ion etch gas in a high pressure (300 to 500 mtorr) single wafer plasma reactor, etch barriers are formed when silicon combines with the sidewall material, allowing the photo image to be dry transferred from a relatively thin photoresist layer into a much thicker underlying layer.

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In-Situ Resist Hardening for Anisotropic Etching in High Pressure Plasma Reactors

By adding certain agents to a reactive ion etch gas in a high pressure (300 to 500 mtorr) single wafer plasma reactor, etch barriers are formed when silicon combines with the sidewall material, allowing the photo image to be dry transferred from a relatively thin photoresist layer into a much thicker underlying layer.

When using a high pressure reactive ion etch (RIE) reactor to develop a surface hardened photoresist, gases are added in-situ which passivate the sidewalls of the underlying material to prevent undercutting and insure an anisotropic etch. This technology extension allows image transfer techniques to be used which utilize relatively thin photoresist patterns. Through the addition of a hardening agent to the oxygen etch gas, high pressure/high throughput RIE reactors can be used to dry process high aspect ratio photolithographic images.

Referring to Fig. 1, a substrate 10 is thinly patterned with a photoresist 11. The process involves the exposure 12 of the surface of a single level photoresist and the hardening (to form regions 13) of selected portions thereof. Once the etch is below the level of the hardened regions 13, shown in Fig. 2, the isotropic nature of the etch tends to undercut the regions 13. To prevent undercutting and enhance image transfer, a suitable concentration of a hardening agent is mixed with the oxygen etch gas to harden the sidewalls 14 of the und...