Investigation On Silicon Films Deposited By Radio-frequency Or Very-high-frequency Magnetron Sputtering

It has become a kind of effective way to control the structure and properties of the deposited silicon thin films by choosing appropriate discharge driving frequency. By this way, the ion energy, ion flux, plasma density and electron temperature can be effectively controlled, and as a result, depositing the silicon thin films with different structural characteristics. However, this technology is mainly applied in the plasma- enhanced chemical vapor deposition(PECVD), the influence of the driving frequency on the growth and structure of the silicon films deposited by magnetron sputtering is seldom reported. In this work, the effect of driving frequency on deposition and property of the silicon films deposited by the radio-frequency and very-high-frequency magnetron sputtering is investigated.This thesis studies the deposition characteristics, atructure and property of the silicon films deposited at the sputtering frequency of 2MHz, 13.56 MHz, 27.12 MHz and 60 MHz as well as the sputtering power from 100 W to 250 W. It is found that the silicon films deposited at the sputtering frequency of 13.56 MHz and 27.12 MHz consist of the large size grains and more amorphous phase. However, the silicon films deposited at the sputtering frequency of 2MHz and 60 MHz consist of the small size grains and more crystalline phase. In order to analyze the possible relationship between the growth and structure of silicon films and the plasma properties, the ions energy, ion flux, plasma density and electron temperature of the magnetron sputtering discharge were measured by retarding field energy analyzer and Langmuir probe. It is found that with the increase of sputtering driving frequency, the ions energy and the electron temperature increase, while the ions flux and the plasma density decrease. The lower deposition rate, small particle size and the small average mean roughness can be attributed to the decrease of ions flux. The increase of ions energy enhances the diffusion of adsorption atoms, beneficial to the formation of nanocrystalline silicon(nc-Si). Therefore, the structure of silicon thin films can change largely with the sputtering frequency. Because the higher ions energy, the lower ions flux and lower growth rate of silicon films in the 60 MHz very-high-frequency(VHF) sputtering were found, this thesis further conducts a preliminary exploration on the fabrication of silicone-like films on the Ag(111) films substrates by 60 MHz VHF magnetron sputtering. Therefore, the driving frequency in the magnetron sputtering is an important factor affecting the growth and structures of the silicon films. The growth, structures and property of silicon films can also be effectively controlled by driving frequency in the magnetron sputtering.