AVS 59th Annual International Symposium and Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS-ThP

Paper PS-ThP45
Experimental and Simulation Studies of Capacitively Coupled Silan-Hydrogen Plasmas for Deposition of m-C Si Film

Thursday, November 1, 2012, 6:00 pm, Room Central Hall

Session: Plasma Science and Technology Poster Session
Presenter: C.-H. Fan, National Tsing Hua University, Taiwan, Republic of China
Authors: C.-H. Fan, National Tsing Hua University, Taiwan, Republic of China
S.-E. Lien, National Tsing Hua University, Taiwan, Republic of China
K.-C. Leou, National Tsing Hua University, Taiwan, Republic of China
C.-H. Hsieh, Institute of Nuclear Energy Research, Taiwan, Republic of China
M.-C. Wang, Institute of Nuclear Energy Research, Taiwan, Republic of China
C.-F. Ai, Institute of Nuclear Energy Research, Taiwan, Republic of China
Correspondent: Click to Email
Capacitively coupled SiH4/H2 plasmas (CCP) have benn widely employed for depostion of Si film for applications such as thin film transistors and thin film solar cells. For Si thin film solar cells, requirements for yielding higher vonversion efficiency at a lower cost calls for a high rate and high uniformity plasma porcess for deposition of microcrystalline Si film. A better understanding of the plasma discharge is needed. In this study, a VHF SiH4/H2 CCP discharge has been investigated by both numerical simulation, based on fluid model, and experimental study employing plasma optical emission spectroscopy analysis. Simulation was performed for VHF SiH4/H2 CCP operated at 27.12 MHz with 27 species and 47 reactions. Simulation results show that, for a power density of 0.4 W/cm2, a gas pressure of 600 Pa and a SiH4/H2 flow rate ratio, or hydrogen dilution ratio, of 2.5/200, electron density profile is quite unifrom in the discharge region with a plasma desity up to 1.8Χ1016 m-3. For the key species related to the film growth, i.e., SiH3 and H, the densities of their fluxes arriving on the grounded substrate surface are uniform. Their ratio, which controls the crystaline fraction of the Si film, is strongly dependent on plasma parameters, such as rf power, hydrogen dilution dilution ratio and gas pressure. Results from experimental OES analysis show similar trends as predicted by the simulation as rf power and hydrogen dilution ratio were varied but little correlation was found as gas pressure was changed. The discrepency, however, can be explained by analyzing the reactions responsible for the production and loss of SiH3 and SiH2. The detailed results from simulation and OES analysis of the parametric analysis ob varying, rf power, gas flow rates and gas pressures will be presented.

*Work supported by the National Science Council of ROC.