We have developed a manufacturing system which is capable of forming SiO2 thin films at a rate as high as 1 μm/min by CO2 laser evaporation.
The system is equipped with a nozzle with an orifice slightly larger than the beam diameter. Oxygen is introduced into the nozzle and ejected through the orifice to suppress the deposition of the evaporated material on the ZnSe optical window for the laser beam. By feeding only several sccm of oxygen it is possible to continue the film forming process for up to 200 hours.
Oxygen feeding is also effective in improving the adhesion strength of SiO2 thin films formed on stainless steel plates. The substrate temperature to obtain an adhesion strength of more than 50 MPa was lowered from 650K to 470K by oxygen feeding.