Superconformal chemical vapor deposition of thin films in deep features

The authors report a new and potentially widely applicable method for the chemical vapor deposition (CVD) of films with a superconformal thickness profile in recessed features, i.e., the rate of growth increases with depth away from the opening. Provided that the aspect ratio of the feature is not too large, deposition initially affords a “V” shaped profile; continued deposition eventually fills the feature without leaving a void or seam of low-density material along the centerline. Superconformal deposition occurs under the following set of conditions: (1) growth involves two coreactants; (2) the deposition rate depends directly on the surface concentrations of both coreactants; (3) the molecular diffusivities of the coreactants are different; and (4) the partial pressures of the coreactants are chosen such that the surface coverage of the more rapidly diffusing coreactant is relatively small, and therefore rate-limiting, near the opening. The latter condition can be fulfilled if the more slowly diffusin...