To improve the stable efficiency of a micromorph silicon tandem solar cell,series of phosphorous doped silicon oxide films were fabricated by radio frequency plasma enhanced chemical vapor deposition(RF-PECVD).By varying the influences of process parameters,such as the CO2/SiH4 gas flow ratio,deposition power and phosphorus doping ratio,on the material optical and electrical properties are discussed.The silicon oxide films whose properties can be controlled in a wide range are obtained.