Electron, ion and neutral temperatures are measured in an Ultra-High-Frequency (UHF) plasma by Langmuir probe and Doppler-shifted laser-induced fluorescence. The electron, ion and neutral temperatures are found to be 1.5 - 2.0 eV (Ar plasma), 0.066 eV for Ar- and 0.036 eV for Ne, respectively, and are lower than those reported for electron cyclotron resonance and helicon wave plasmas. The low temperatures cause lower dissociations of CHF3 gas even in the plasma production region of the UHF plasma source. The plasma is expected to improve significantly the selectivity of SiO2 to underlying Si. Additionally, the plasma can be used to accomplish notch-free poly-Si etching profile and microloading-free Si trench etching with a high etching rate and high anisotropy with a narrow space pattern of less than 0.3 μm. It is suggested that the charge accumulation with the narrow space pattern should be eliminated because of the low electron temperature in the UHF plasma.
|Number of pages||8|
|Journal||NEC Research and Development|
|Publication status||Published - 1996|
- Plasma etching
- Uhf (ultra-high-frequeney) plasma
ASJC Scopus subject areas
- Electrical and Electronic Engineering