Comparison of TiN films produced by TDEAT (Ti[N(C2H5)2]4), TDMAT (Ti[N(CH3)2]4), and a new precursor TEMAT (Ti[N(CH3)C2H5]4)

TiN films have been deposited by chemical vapor deposition (CVD) from a new TiN precursor, tetrakis(ethylmethylamino)titanium (TEMAT), and compared with those from tetrakis(diethylamino)titanium (TDEAT) and tetrakis(dimethylamino)titanium (TDMAT) in terms of film quality and conformality. The TDEAT process at 350°C provides films with low resistivity of ˜2500μΩ-cm and 30% carbon. In addition, films deposited from TDEAT contain no oxygen and show good stability in resistivity with time. Furthermore, this process provides bottom-coverage ranging from 65% at 275°C to 30% at 350°C. In contrast, excellent bottom-coverage of ˜90% over 0.5μΩ contact holes is obtained by the TDMAT process. However, films deposited from TDMAT are air-reactive upon air-exposure, resulting in a large increase in resistivity when exposed to air. The use of TEMAT, possessing physical properties between those of TDMAT and TDEAT, allows less air-reactive and better crystalline films, compared with TiN films from TDMAT. It is also observed that the carbon level is ˜2x lower than that in TiN films from TDEAT. Futhermore, this process provides good step-coverage in 0.35μΩ contacts with an aspect ratio of 2.9. Consequently, the TEMAT process can be an attractive choice for sub-0.5 μΩ application.