Plasma-Enhanced Chemical Vapor Deposition of SiO2 Thin Films at Atmospheric Pressure by Using HMDS/Ar/O2
- SiO$_2$-like thin films were deposited at low temperature ($<$50 $^circ$C) by using atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) with a pin-to-plate type dielectric barrier discharge (DBD) and a gas mixture containing hexamethyldisilazane (HMDS)/Ar/O$_2$. The film's characteristics were investigated as a function of the HMDS flow rate. Increasing the HMDS flow rate from 100 sccm to 500 sccm increased the deposition rate almost linearly from 46.4 nm/min to 141.1 nm/min. However, increasing the HMDS flow rate increased impurities such as C and H and the surface roughness of the deposited film. Fourier transform infrared measurement showed an increase of -OH and -(CH$_3$)$_x$ ($x$ = 1, 2 or 3) in the film with increasing HMDS flow rate. The increased surface roughness and impurities in the deposited film are believed to be related to incompletely dissociated HMDS at higher HMDS flow rates. By optimizing the oxygen flow rate and the HMDS flow rate, we believe that a SiO$_2$ thin film with low impurity and low surface roughnesses can be obtained. In this experiment, with the HMDS flow rate in the range of 100 $sim$ 200 sccm, SiO$_2$-like thin films having low surface roughness and low impurities ($<$3.7 \% C) could be obtained.
- Keywords: Atmospheric pressure, Silicon dioxide, HMDS (hexamethyldisilazane)