| AVS 55th International Symposium & Exhibition | |
| Thin Film | Tuesday Sessions |
| Session TF-TuA |
| Session: | Applications of ALD II |
| Presenter: | J.E. Maslar, National Institute of Science and Technology |
| Authors: | J.E. Maslar, National Institute of Science and Technology W.A. Kimes, National Institute of Science and Technology J.T. Hodges, National Institute of Science and Technology B. Sperling, National Institute of Science and Technology D.R. Burgess, National Institute of Science and Technology E.F. Moore, National Institute of Science and Technology |
| Correspondent: | Click to Email |
In situ monitoring of atomic layer deposition (ALD) processes has the potential to yield insights that will enable improved efficiencies in film growth, in the development of deposition recipes, and in the design and qualification of reactors. In situ diagnostics potentially can be used to measure a number of parameters. Measuring precursor flux into the reactor is a relatively common application. However, such measurements are of limited value when trying to optimize deposition chemistry. Potentially more useful would be measurements of deposition precursor and product gas phase concentrations near the wafer surface. Such measurements would allow one to probe the properties of the near-surface thermal/gas velocity boundary layer that exists in many industrial ALD reactors. Since the properties of this boundary layer are strongly impacted by the state of the wafer surface, gas phase measurements in the boundary layer can provide information about the state of the wafer surface. In this work, semiconductor laser-based gas phase absorption measurements performed near the wafer surface are being investigated for use as in situ, real time diagnostics for ALD. The material system selected for investigation is hafnium oxide ALD using tetrakis(ethylmethylamino) hafnium (TEMAH) and water. Absorption measurements of water vapor were performed in the near-infrared (NIR) using a distributed-feedback (DFB) diode laser and employing a wavelength modulation detection scheme. Assuming complete reaction, the products of the TEMAH and water reaction are hafnium oxide and methyl-ethyl-amine, a volatile species under deposition conditions. Absorption measurements of methyl-ethyl-amine were performed in the NIR using an external-cavity diode laser (ECL) and employing an amplitude modulation detection scheme. In situ, time-resolved Fourier transform infrared spectroscopy measurements were used to compliment the laser-based measurements. Measurements were performed in a single-wafer, warm-wall reactor. Deposition precursor and product concentrations near the wafer surface were measured under a range of deposition conditions in an effort to correlate gas phase measurements with surface processes. The performances of the DFB laser-based and ECL-based measurement systems will be compared. In addition, efforts to model the observed concentration gradients using reactor-scale computational fluid dynamics models will be discussed.