Method to increase the compressive stress of PECVD silicon nitride films

A method of forming silicon nitride, the method comprising:

• disposing a substrate including a surface in a processing chamber;
• forming a silicon oxide buffer layer over the surface;
• and
• depositing silicon nitride over the buffer layer by a chemical reaction in a plasma between a silicon-containing precursor and a nitrogen-containing precursor in the presence of a hydrogen gas flow, wherein the silicon nitride is deposited as a film stack comprising an initiation layer formed in the absence of the hydrogen gas flow, followed by a high compressive stress layer formed in the presence of the hydrogen gas flow.

A method of preventing defects in a device, the method comprising:

• depositing a silicon nitride initiation layer on a surface in the absence of a flow of hydrogen gas;
• depositing a high compressive stress silicon nitride layer on the silicon nitride initiation layer by reaction between a silicon-containing precursor and a nitrogen-containing precursor in a plasma in a presence of a flow of hydrogen gas;
• and
• etching back the high compressive stress silicon nitride layer with a diluted NF3 plasma.