Process optimization and PFC emission reduction using a c-C/sub 4/F/sub 8/ chamber cleaning process on a novellus concept 1 dielectric PECVD tool

While the new generation of chemical vapor deposition (CVD) tools adapts NF/sub 3/ as a chamber clean gas to reduce perfluorocompound (PFC) reductions, process optimization (C/sub 2/F/sub 6/) and alternative C/sub x/F/sub y/ clean chemistries are options for the installed-base tools. From a previous study comparing the various C/sub x/F/sub y/ chamber clean chemistries, we further conducted a production test in a 150-mm wafer fabrication facility comparing the best alternative C/sub x/F/sub y/ clean chemistry (C/sub 4/F/sub 8/ clean) with an optimized C/sub 2/F/sub 6/ clean process on a Novellus Concept 1 Dielectric tool running TEOS-based SiO/sub 2/ CVD. Gas flow rates, chamber pressure, and oxygen volume percentages were studied as variables to develop an optimal c-C/sub 4/F/sub 8/ process recipe for maintaining or improving cleaning efficiency while reducing gas consumption and PFC emissions compared to the optimized C/sub 2/F/sub 6/ process. After the initial experimental matrix was completed, several single-variable experiments were run to fine tune the recipe. Based on the data analysis and the model results from the design of experiment, two optimal C/sub 4/F/sub 8/ cleaning processes were identified. Both processes significantly lowered gas consumption and PFC emissions. Marathon process testing showed no adverse impact on film properties or device yield.