Browse Prior Art Database

Multiple Sidewall Process for Trench Masks

IP.com Disclosure Number: IPCOM000038529D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Danner, DA: AUTHOR [+3]

Abstract

This article relates generally to integrated circuit fabrication and, more particularly, to the formation of trenches having high aspect ratios. Deep, narrow trenches of sub-micron dimensions can be formed with standard optical lithography by first etching a wide trench and reconstructing walls to form narrow trenches. In Fig. 1, oxide layer 1 is either deposited or grown on substrate 2 to the thickness necessary to mask the trench etching. Layer 1 is masked and an area is etched with a fluorocarbon and hydrogen to leave wide trench 3 with a shallow oxide coating 4 at the bottom of the trench. In Fig. 2, silicon nitride spacers 5 are formed on the trench sidewalls, followed by deposition of silicon dioxide spacers 6 on spacers 5. The oxide surface is again oxidized for protection. In the next step seen in Fig.

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Multiple Sidewall Process for Trench Masks

This article relates generally to integrated circuit fabrication and, more particularly, to the formation of trenches having high aspect ratios. Deep, narrow trenches of sub-micron dimensions can be formed with standard optical lithography by first etching a wide trench and reconstructing walls to form narrow trenches. In Fig. 1, oxide layer 1 is either deposited or grown on substrate 2 to the thickness necessary to mask the trench etching. Layer 1 is masked and an area is etched with a fluorocarbon and hydrogen to leave wide trench 3 with a shallow oxide coating 4 at the bottom of the trench. In Fig. 2, silicon nitride spacers 5 are formed on the trench sidewalls, followed by deposition of silicon dioxide spacers 6 on spacers 5. The oxide surface is again oxidized for protection. In the next step seen in Fig. 3, nitride spacers are removed by a highly selective wet chemical or dry etch, such as hot phosphoric acid or a fluorocarbon and oxygen plasma etch. This leaves trenches 7 that can be transferred into the silicon. This process permits the nitride deposition to determine the trench widths and their spacing to be controlled by the oxide deposition. The number of trenches is controlled by the original area imaged.

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