The concentration of argon in rf-sputtered silicon films has been measured by Rutherford backscattering tecknique as a function of operation frequency and discharge pressure. The concentration increases with increasing frequency but dcreases with increasing pressure. The density of sputtered silicon films vary from 0.6 to 0.8 relative to the silicon substrate. It depends only on pressure conditions. However, the deposition rate depends on both frequency and pressure. There exists a steep drop in the deposition rate and also on the argon concentration curve when the frequency is at about the tank frequency.