Measurement of plasma-surface interaction in CF_4/Ar RF-ICP by using CT-OES
Abstract
Highly selective SiO2 etch over Si is required to manufacture ULSI devices. Reactive ion etching using polymerizing fluorocarbon chemistries provides the process for selective dry etching of SiO2 over Si. A number of species including electrons, ions, and radicals are generated in the plasma processing by reactions in gas phase and on surface. A large amount of highly reactive fluorine atoms, fluorocarbon radicals, ions from the plasma interact with the substrate and produce etch products. These etch products, primarily SiF4 and SiF_2, diffuse back into the bulk plasma where they are dissociated and ionized by electrons and the resultant products are transported and redeposited onto the substrate and/or surface. That is, the plasma structure will be quite different whether the surface is exposed to etching or not. It will be essential to investigate the spatio temporal characteristics of plasma structure during etching process. In our recent study, we have mainly measured spatio temporal structure of excited SiF(A^2 °^+) and F(3^4D_7/2) in CF_4/Ar mixture driven by RF(13.56MHz)-ICP during Si etching, by using CT(Coumputerized Tomography)-OES(Optical Emission Spectroscopy) system. We discuss the plasma structure during Si etching as a function of LF(500 kHz) bias source.
- Publication:
-
APS Annual Gaseous Electronics Meeting Abstracts
- Pub Date:
- September 2004
- Bibcode:
- 2004APS..GECRW2003M