Methods and apparatus for forming nitrogen-containing layers are provided herein. In some embodiments, a method includes placing a substrate having a first layer disposed thereon on a substrate support of a process chamber; heating the substrate to a temperature of at least about 250 degrees Celsius; and exposing the first layer to a radio frequency (RF) plasma formed from a process gas comprising nitrogen while maintaining the process chamber at a pressure of about 10 mTorr to about 40 mTorr to transform at least an upper portion of the first layer into a nitrogen-containing layer. In some embodiments, the process gas includes ammonia (NH3).