All hot wire CVD TFTs with high deposition rate silicon nitride (3nm/s)

Abstract: Using the hot wire (HW) chemical vapor deposition (CVD) method for the deposition of silicon nitride (SiN x ) and amorphous silicon (a-Si:H) thin films we have achieved high deposition rates for device quality materials up to 7.3nm/s and 3.5nm/s, respectively. For thin films of SiN1.3, deposited at 3nm/s, the mass-density of the material reached a very high value of 3.0g/cm3. The silane utilization rate for this fast process is 77%. The high mass-density was consistent with the low 16BHF etch rate of 7nm/min. We tested this SiN1.3 in “all hot wire” thin film transistors (TFTs), along with a-Si:H material in the protocrystalline regime at 1nm/s. Analysis shows that these “all hot wire” TFTs have a V th =1.7–2.4V, an on/off ratio of 106, and a mobility of 0.4cm2/Vs after a forming gas anneal. We therefore conclude that the HWCVD provides SiN x materials with dielectric properties at least as good as PECVD does, though at a much higher deposition rate and better gas utilization rates. [Copyright &y& Elsevier]