In situ Fourier transform P-polarized infrared reflection absorption spectroscopic investigation of an interface properties of SiO 2/Si(100) deposited using electron cyclotron resonance microwave plasma at room temperature

Abstract

Amorphous SiO 2 films have been deposited onto the Si substrate, without heating, using sputtering-type electron cyclotron resonance (ECR) microwave plasma. In situ Fourier transform P-polarized infrared reflection absorption spectroscopy (ISFT-PIRRAS) has been used to study the properties of a-SiO 2/Si interface. The results from ISFT-PIRRAS monitoring indicated that the interface stress led to significant distortion in the local structure, which resulted in the broadening of a transverse optical mode (TO 3) located at 1050 cm −1. The interface stress decreased with increased film thickness. In addition, the longitudinal optical phonon mode (LO 3, located at 1223 cm −1) related to TO 3 mode was observed due to Berreman effect [B. Harbecke, Appl. Phys. A: Solids Surf. 38 (1985) 263]. This phonon mode is very sensitive to SiO 2 film thickness, which enables it to be used to detect and characterize ultra thin SiO 2 film. When the film thickness is over 30 nm, a non-linear dependence of the intensity of LO 3 mode on film thickness was observed. However, the TO 3 mode has a near linear dependence on film thickness. Thus, it is more accurate and suitable to detect thick film by monitoring TO 3 mode intensity.