Micro-jet plasma CVD with HMDSO/O2

Micro-jet plasma chemical vapor deposition can produce quartz-like localized coatings from HMDSO/O2 (hexamethyldisiloxane) mixture with an extremely high deposition rate (120 μm/s). The reaction between HMDSO and O2 takes place in the jet. Less than 0.5 ms is required to remove the methyl groups from the monomer and to oxidize Si. The chemical composition of the product is close to SiO2. It was found that the optimal parameters for a well-defined deposition differ with the capillary's inner diameter (ID) and depend strongly on the jet expansion. The lower the background pressure pc related to the capillary exit pressure, the more the jet expands. A small ID requires a relatively high flux and a high pc for a confined jet which, in turn, ask for a high power density for the excitation of the gas.