Infrared and near-infrared spectroscopic probing of atomic layer deposition processes

The focus of this paper is the application of Fourier transform infrared spectroscopy (FTIR) and near infrared-tuneable diode laser spectroscopy (NIR-TDLAS) as in situ tools to monitor the formation of gas phase products during atomic layer deposition (ALD). Two studies are chosen to highlight the importance of monitoring the gas phase, in this surface driven process, for both mechanistic and reactor dynamics considerations. The first study is the FTIR monitoring of the ALD of HfO2, from Hf[N(CH3)2]4 and H2O where it was found that, in addition to the expected HN(CH3)2, gas phase species were generated including CO, CH4 and HCN. The second ALD system investigated was the growth of Al2O3 from Al(CH3)3 and H2O employing NIR-TDLAS as a real time in situ probe to monitor the evolution of CH4.