Moisture barrier properties of plasma enhanced chemical vapor deposited SiCxNy films on polyethylene naphthalate sheets and epoxy molding compound

Ternary Si–C–N films were produced in a radiofrequency plasma enhanced chemical vapor deposition reactor applying the precursor gases silane, methane, and nitrogen or ammonia. The properties of the films to function as external moisture barrier layers were investigated with emphasis on the correlation of deposition parameters and moisture permeation rate. The moisture penetration through the films has been investigated in water vapor permeation experiments and capacitance measurements from humidity sensors in plastic packages. The moisture resistance is mainly influenced by the stress in the films with best results for those samples exhibiting no or low compressive stress.