Preparation Of High Reflectance Coating By PECVD

Plasma enhanced chemical vapor deposition(PECVD) is widely used in the LED production,micro mechanical manufacture,solar anti-reflection film,etc.Now it has many applications in preparation of optical thin film, because of low reaction temperature, fine film uniformity, and can be used in preparation of thin film materials with large area, high density, high laser damage threshold.In this article,silicon nitride(SiNx) thin film material with high refractive index, silicon oxide(SiOx) thin film material with high laser induced damage threshold(LIDT) and fluoride silicon oxide(SiOxFy) thin film material with low refractive index were prepared by PECVD,which can be used in preparation film of high LIDT,the best preparation technology,deposition rate,process repeatability and LIDT of SiNx material, SiOx material and SiOxFy material were studied, and the high reflectance film at 1064 nm was fabricated.The main results are as follows:1) The optimal parameters for the preparation of SiNx is that the flow rate of SiH4 and N2 are contained at 72sccm and 70sccm,RF is 160W, working pressure is 70Pa,the reaction temperature is 300℃.The refractive index of SiNx is 1.95,the deposition rate is 9.3 nm/min, LIDT is 24.1 J/cm2,the process repeatability shows that precision of refractive index could be controlled less than 1.5%, the process repeatability shows that precision of physical thickness could be controlled less than 7%;2) The optimal parameters for the preparation of SiOx is that the flow rate of SiH4 and N2O are contained at 60sccm and 40sccm,working pressure is 20 Pa,RF is 200W,the reaction temperature is 300℃. The refractive index of SiOx is 1.46,the deposition rate is 14 nm/min, LIDT is higher than 39.8 J/cm2,the process repeatability shows that precision of refractive index could be controlled less than 1.5%, the process repeatability shows that precision of physical thickness could be controlled less than 8%;3) The optimal parameters for the preparation of SiOxFy is that the flow rate of SiH4,N2O and C2F6 are contained at 60sccm,40sccm and 6sccm, working pressure is 20 pa,RF is 200 w, the reaction temperature is 300℃.The refractive index of SiOxFy is 1.42,the deposition rate stability in 10 nm/min after 15 min, LIDT is 26.4 J/cm2,the process repeatability shows that precision of refractive index could be controlled less than 1.5%, the process repeatability shows that precision of physical thickness could be controlled less than 6%;4) Adopting PECVD technology and using the high and low refractive index SiNx and SiOxFy thin film materials successfully prepared 1064nm high reflective film,the structure is G|(HL)nH|A,by testing its transmittance,reflectance,laser induced damage threshold results show that the preparation of high reflective film transmittance is 0.08% at 1064 nm,absolute reflectivity is 99.11%,LIDT is 11.6 J/cm2.