Control Technology Of Refractive Index Of Optical Thin Films Deposited By PECVD

The optical films prepared by PECVD have some distinctive advantages.The optical film has excellent physical characteristic.A variety of optical film refractive indexes can be obtained by controlling precursor gases ratio.The research results of controlling method and precision manufacturing process of refractive index be conducive to prepare precision optical thin films by PECVD.The thin films are deposited on K9glass substrate by PECVD.The paper mainly discusses the technology of controlling the refractive index.After a large number of process experiments, method to control the refractive index of thin films is explored and the refractive index range are obtained. The relation of different process parameters on the accuracy of refractive index are discussed. The manufacturing precision of different refractive index of thin films is analyzed. When thin film refractive index of manufacturing accuracy is0.01, the range of thin film deposition process parameters is analyzed too.The error of the thickness controlling with changing thickness is analyzed and the error range of thickness fabrication is obtained. The results are as follows:1) By controlling reaction gases ratios,the refractive index of optical thin films will be precisely controlled.The refractive index range is1.36-2.06.2) Thin films with the target of refractive index of1.40,1.60,1.80,2.05are deposited by PECVD.The test results show that relative tolerances respectively are0.38%,0.425%,0.49%,0.36%.3) When the relative tolerance of the refractive index is less than1%, the preparation process parameters range of SiOxNy film with the refractive index of1.60are respectively, reaction pressure:17-60Pa, reaction temperature:250～330℃, RF power:190～270w.4) The results show that the error of film thickness increases as the film thickness increases.when Film thickness_is within500nm,the relative tolerances of the refractive index is less than3%.