Dual source APCVD synthesis of TaN and NbN thin films on glass from the reaction of MCl5 (M = Ta, Nb) and 1,1,1,3,3,3-hexamethyldisilazane

Abstract

Niobium nitride films were synthesised by the reaction of niobium pentachloride and hexamethyldisilazane (NH(SiMe₃)₂, HMDS) under atmospheric pressure chemical vapour deposition (APCVD) conditions. Films were deposited at 400–580 °C in a cold wall CVD reactor. X-ray photoelectron spectroscopy showed that the films consist of niobium and nitrogen with binding energy shifts of 206.8 eV for Nb 3d and 396.8 eV for N 1s. In a similar manner tantalum pentachloride was reacted with HMDS under APCVD at 400–580 °C to give reflective silver films consisting of tantalum nitride. EDAX analysis showed the presence of tantalum and nitrogen in these films. Both sets of films were hard and chemically inert to common solvents and acids, they were also crystalline at substrate temperatures of 550 °C and above showing the typical cubic NaCl pattern of refractory nitrides (TaN a = 4.34(1) Å; NbN a = 4.33(1) Å). Raman patterns of the films were somewhat indistinct but matched bulk samples. The films were an aesthetically pleasing silver colour and showed no change in optical properties when stored in air for over two years; the films have potential as decorative reflective coatings.