MEMS devices are susceptible to surface conditions because they are seldom passivated. For example, electrical and optical performances are affected when unpassivated surfaces adsorb or chemically react with ambient gases. Stiction can occur if shock impacts cause these high-energy surfaces to touch. Unfortunately, it is difficult to passivate MEMS wafers due to microstructure flatness requirements, metal temperature limitations and surface charging during low temperature plasma processes. Some SAM coatings are reasonable candidates. However, organics do not normally survive the cerpac process used to package ADXL accelerometers (several furnace passes in air at 430-450C). This presentation will describe a new MEMS passivation process based on a custom synthesized diphenyl siloxane. Organics with the best thermo-oxidative resistance contain phenyl rings so vapor deposited diphenyl siloxane films were evaluated on polysilicon accelerometers. Silicones (molecules with a silicon oxide backbone) were used to transport and bond phenyl rings to the sensor surface. As a result, the native oxide is modified by formation of a low-energy (organic-rich) surface that survives the packaging process. This approach also minimizes contamination concerns because any degradation products are essentially identical to the native oxide that already exists on polysilicon surfaces. A variety of deposition conditions and two types of equipment were evaluated for both electrical and stiction characteristics. Varying the type of diphenyl siloxane caused large differences in anti-stiction performance. Control of the final process is impressive. For example, 100 wafer coating runs have a thickness uniformity of +/- one angstrom. There is no practical way to measure coatings on MEMS surfaces with this level of precision. Therefore, specially prepared monitor wafers are placed in each furnace boat. Early results show that run to run uniformity is also in the +/- one angstrom range.