Use of langmuir probes for monitoring of precursor concentrations during plasma activated chemical vapor deposition of hard coatings

Langmuir-probe characteristics were measured during the deposition of hard zirconium nitride films in H₂ plasmas with tetrakis(diethylamido)-zirconium-Zr[N(C₂H₅)₂]₄- as a precursor. A combination of fast repeatable probe sweeps and hysteresis measurements indicated undisturbed characteristics for approximately 1 h. Since the electron concentration is highly dependent on the partial pressure of the precursor it is possible to use probes as sensors to monitor precursor concentration in a discharge.