X-ray photoelectron spectroscopy study of TiN films produced with tetrakis(dimethylamido)titanium and selected N-containing precursors on SiO2

Abstract

Low pressure chemical vapor deposition TiN films were produced on SiO2 by codosing tetrakis(dimethylamido)titanium (TDMAT) with selected N-containing precursors. The films were grown at total pressures ranging from 10−4 to 10−3 Torr and temperatures between 523 and 773 K. Film composition and chemical states were determined, without exposure to ambient pressure, using x-ray photoelectron spectroscopy (XPS). Our primary goal was to evaluate how precursor ligands affect C and N incorporation into TiN films. To this end, methylhydrazine (MH), dimethylhydrazine (DMH), and 1-aminopiperidine (AP) were chosen for their steric differences, and t-butylamine (TBA) and aniline allowed us to assess how C and N incorporation are affected by the C–N bond in the aminolike compounds versus the N–N bond in the hydrazinelike compounds. At all growth temperatures, a decrease in the carbon concentration and an increase in the N concentration were observed for the MH and DMH cases when compared to TDMAT alone, while C content increased for aniline. AP caused only a slight reduction of C at temperatures of 673 K and above. Growth temperature affected film composition and the chemical states of C, N, and Ti. At 623 K, DMH and MH reduced the C/Ti ratio from 1.0 with TDMAT alone to 0.2, while aniline increased C/Ti to 2.0 and AP and TBA had little effect. The addition of the N-containing precursors causes the XPS C 1s peak to broaden and shift to higher binding energy; the N 1s peak also broadened, suggesting that, compared to TDMAT alone, more C–N bonds are formed. Furthermore, the Ti 2p peak shifted to higher binding energy and became broader upon codosing, suggesting the incomplete conversion of Ti (IV) to Ti (III) in the TiN film. Postdosing with MH and DMH supports the conclusion that surface reactions occur between TDMAT and the hydrazinelike precursors.