Various embodiments herein relate to methods and apparatus for depositing a bilayer barrier layer on a substrate. The bilayer barrier layer may include a first sub-layer designed to protect underlying halide-sensitive layers from damaging halide-containing chemistry, as well as a second sub-layer designed to protect underlying materials from damage due to oxidation. In a number of embodiments the first sub-layer is layer having a high carbon content, and the second layer is silicon nitride. The silicon nitride second sub-layer may be deposited with halide-containing chemistry that would otherwise damage halide-sensitive materials, if not for the presence of the first sub-layer. The resulting bilayer barrier layer provides high quality protection for underlying materials.