A two-temperature technique for PECVD deposition of silicon dioxide

A new technique has been developed and analyzed for plasma-enhanced chemical vapor deposition (PECVD) silicon dioxide films, First, a thin cap layer is deposited at a low temperature and the film is subjected to an in-situ hydrogen plasma treatment. Then, the temperature is raised to the final value and the deposition continued to the desired thickness. It is shown that interrupting the deposition for in-situ sample treatment can be used to lower the interface trap density. Several variations are examined, and it is seen that a thin cap layer is best, along with a higher initial temperature. A variety of hydrogen treatments are shown to effectively reduce the trap density from that of a standard one-temperature deposition. The midgap trap densities obtained are among the best achieved with a direct PECVD system.<>