Anisotropic Etching of Si and WSiN Using ECR Plasma of SF6–CF4 Gas Mixture
- 1 June 2000
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 39 (6R) , 3672-3676
- https://doi.org/10.1143/jjap.39.3672
Abstract
The characteristics of Si etching with electron cyclotron resonance (ECR) plasma of SF6–CF4 are studied in order to improve anisotropy in dry etching using fluoride gases. Si undercutting is decreased by increasing the amount of CF4. Si patterns with vertical sidewalls are obtained with an etch rate of 40 nm/min. Oxygen addition to SF6–CF4 increases Si/SiO2 etching selectivity to more than 10, but does not cause any undercutting. It is concluded that carbon (C) that decomposes from CF4 protects the pattern sidewall from undercutting by fluorine radicals. These results are applied to the anisotropic etching of WSiN as the gate material for GaAs metal-semiconductor field effect transistors (MESFETs). WSiN patterns are more vertical when the chamber inner wall exposed to SF6–CF4 ECR plasma is stainless steel rather than quartz. This is attributed to the reduction of the amount of CO, which possibly forms volatile tungsten-carbonyl [W(CO)6] and, along with fluorine radicals, causes undercutting. It is confirmed that the stainless steel inner wall does not cause serious wafer contamination by metallic elements when WSiN patterns are almost vertically etched.Keywords
This publication has 11 references indexed in Scilit:
- 0.1 μm WSiN-gate fabrication of GaAs metal-semiconductor field effect transistors using electron cyclotron resonance ion stream etching with SF6–CF4–SiF4–O2Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1997
- High-performance 0.1 μm-self-aligned-gate GaAs MESFET technologyIEEE Transactions on Electron Devices, 1997
- Thermally stable InGaP/GaAs Schottky contacts using low N content double layer WSiNJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1996
- Electron cyclotron resonance ion stream etching with high uniformity and accuracy for metal–oxide–semiconductor gate fabricationJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1994
- Processing Uniformity Improvement by Magnetic Field Distribution Control in Electron Cyclotron Resonance Plasma ChamberJapanese Journal of Applied Physics, 1993
- Reactive ion stream etching utilizing electron cyclotron resonance plasmaJournal of Vacuum Science & Technology B, 1986
- Low Temperature Chemical Vapor Deposition Method Utilizing an Electron Cyclotron Resonance PlasmaJapanese Journal of Applied Physics, 1983
- Microwave Plasma Etching of Si with CF 4 and SF 6 GasJournal of the Electrochemical Society, 1982
- Plasma etching—A discussion of mechanismsJournal of Vacuum Science and Technology, 1979
- Plasma etching of Si and SiO2—The effect of oxygen additions to CF4 plasmasJournal of Applied Physics, 1978