Etching of silicon dioxide selectively to silicon nitride and polysilicon

US5505816A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Michael Barnes · San Ramon, US
• John H. Keller · Newburgh, US
• William M. Holber · Winchester, US
• Tina J. Cotler · Newburgh, US
• Jonathan D. Chapple-Sokol · Poughkeepsie, US
• Dragan Podlesnik · Palo Alto, US

Key dates

• Filing date: Dec 16, 1993
• Grant date: Apr 9, 1996
• Expiry date: Dec 16, 2013

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S438/906
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

Silicon dioxide on a substrate is directionally etched using a hydrogen halide plasma which is created within an etch chamber. The method selectively etches silicon dioxide relative to polysilicon and silicon nitride. A substrate and the combination of NH.sub.3 and NF.sub.3 gases or the combination of CF.sub.4 and O.sub.2 gases mixed with H.sub.2 and N.sub.2 gases are located within an etch chamber. An electrical field is created within the etch chamber causing the gas mixture to form a plasma. The negative charge at the bottom of the chamber attracts the positively charged plasma, thereby etching the substrate in the downward direction. The result is an anisotropic product. The method is also shown to be effective in non-selectively etching thermal and deposited oxides, resulting in a similar etch rate for the different types of oxides.