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 µm and widths 1‐5 µm. 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 15 nm min −1 . An analytical model for determining the sticking probability of the initiating radical (CH 3 ) 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 × 10 −2 –5.0 × 10 −2 . These results suggest that iCVD proceeds via the reaction of a vapor‐phase initiating radical with a surface‐adsorbed monomer.