Thin Polymer Films with High Step Coverage in Microtrenches by Initiated CVD

Initiated (i)CVD is used to deposit thin films of poly(cyclohexylmethacrylate) (pCHMA) in microtrenches of depth 7 mu m and widths 1-5 mu m. By changing the fractional saturation of the monomer vapor, step coverage of 0.85 is achieved for the highest aspect ratio trench studied while maintaining a deposition rate of 1.5 nm min(-1). An analytical model for determining the sticking probability of the initiating radical (CH3)(3)CO is developed, and is experimentally shown to be a function of the fractional saturation of the monomer vapor. For the conditions studied, the sticking probability is in the range 1.1 x 10(-2)-5.0 x 10(-2). These results suggest that iCVD proceeds via the reaction of a vapor-phase initiating radical with a surface-adsorbed monomer.