Dielectric properties of ultra dense (3 g/cm3) silicon nitride deposited by Hot Wire CVD at Industrially relevant high deposition rates

For silicon nitride (SiNx) deposited at 3 nm/s using hot wire chemical vapor deposition (HWCVD), the mass-density reached an ultra high value of 3.0 g/cm3. Etch rates in a 16BHF solution show that the lowest etch rate occurs for films with a N/Si ratio of 1.2, the ratio where also the maximum in mass density occurs. The thus found etch rate of 7 nm/min is much better than that for PECVD layers, even when made at a much lower deposition rate. The root-mean-square (rms) roughness measured on 300 nm thick SiN1.2 layers is only about 1 nm, which is advantageous for obtaining high field-effect mobility in thin-film transistors. SiN1.2 films have succesfully been tested in ?all hot wire´´ thin film transistors (TFTs). SiNx films with various x values in the range 1.0 <x