The effect of pretreatment for SiH4 gas by microwave plasma on Si film formation behavior by thermal CVD

We propose a pretreatment method for monosilane (SiH4) gas by high-density plasma toward the relatively low-temperature formation (<= 600 degrees C) of a crystalline Si film by thermal chemical vapor deposition (TCVD). SiH4 reaction behaviors with the plasma are investigated by using gas-phase Fourier-transform infrared spectroscopy. The dependence of the Si2H6 formation characteristics on total gas flow rate and input microwave power is examined. Si2H6 gas yields with the plasma treatment for SiH4 gas increased with decreasing input microwave power and increased with increasing total gas flow rate. Si films are prepared by TCVD using the plasma-treated SiH4 gas. As a result, the pretreatment for SiH4 gas by high-density plasma affects not only the deposition rate but also the crystallinity of the obtained Si film. The mechanism by which Si film formation is improved by plasma treatment is discussed.