Numerical and Experimental Study of Silane/Hydrogen Plasma for Intrinsic Amorphous Silicon Film Deposition

• Main Authors: Chang, Chin Jung, 張進榮
• Other Authors: Keh-Chyang Leou
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/04225087695340887418

碩士 === 國立清華大學 === 工程與系統科學系 === 104 === The purpose of this study is to investigate the influence of the plasma property on the thin film property. This study includes both experimental and simulation analysis, the simulation part used a two-dimensional fluid model for PECVD (Plasma enhanced chemical vapor deposition) system with silane/hydrogen plasma for the process of the intrinsic amorphous silicon thin film layer through computer simulation, also we can understand the mechanisms of physical and chemical reactions, and comparing the properties of plasma with different process conditions through the simulation results. The experimental part used the plasma spectrum to analyze the correlation between the characteristic spectrums and the properties of the amorphous silicon film layer. At the same time, using the experiment result to match and prove the simulation. In the simulation result, the flux density ratio of Si4H9/SiH3 decrease as power decrease, also it decreases the ion bombardment effect due to the lower potential gradient in the sheath. However, the flux density ratio of Si4H9/SiH3 decrease as power decrease. As the hydrogen dilution ratio increases, the H/SiH3 increases; and the Si4H9/SiH3 has a trend of rise first then fall. As radio frequency increases, the H/SiH3 and the Si4H9/SiH3 increase. The ion bombardment effect is proportional to frequency. In the experimental results, depositing the amorphous silicon thin layer by PECVD under the same parameters from simulation at frequency 27.12 MHz. The best passivation quality was deposited under condition are power is 30 W, hydrogen dilution ratio is 1.5. The minority carrier lifetime is 5.061 ms.. To understand the correlation between the properties and the emission spectrum of the plasma more, using plasma spectrums, H2 Fulcher can observe the similar trend with electron number density at the steady-state plasma. To analyze the correlation between a-Si passivation quality and plasma spectrum, it could find the trends of the plasma spectrum SiH/Hβ*(5 nm) is proportional to the minority carrier lifetime. Comparing the simulation result with properties of a-Si, it could find that the flux density ratio H/SiH3 is similar with the crystallinity and microstructure of the film. The trend of the flux density ratio Si4H9/SiH3 matches with the voids fraction. In conclusion, we could get the better film quality when operating with a lower power, moderate hydrogen dilution ratio and frequency.