Quantitative Infrared Spectroscopy of Tetrakis(dimethylamido)Titanium for Process Measurements

Abstract

Infrared spectroscopy has been widely used for in situ analysis of the gas phase during chemical vapor deposition (CVD) and atomic layer deposition (ALD). For both process monitoring and research applications, accurate determination of absorptivity is often necessary for quantitative work. In this study, we measure reference spectra for vapor-phase tetrakis(dimethylamido)titanium (TDMAT), an organometallic precursor commonly used for both CVD and ALD. The gas cell is heated over the temperature range of (352 to 476) K. We take steps to correct for sample emission, which otherwise is found to cause errors. Systematic changes are observed as the temperature is varied, but integrated absorbance is insensitive to temperature. The implications for infrared-based process measurements are discussed. In the course of this work, we do not observe rapid thermal decomposition of TDMAT at 476 K, which had been reported elsewhere in the literature.

Analysis of Low-k Dielectric Thin Films on Thick Substrates by Transmission FTIR Spectroscopy

“…[1][2][3] Within the semiconductor industry, T-FTIR has been in particular utilized extensively for analysis of the chemical structure of low permittivity (i.e. low-k) dielectric materials typically employed to minimize capacitive signal delays in highly integrated nano-electronic interconnect structures.…”

Nondispersive Infrared Gas Analyzer for Partial Pressure Measurements of a Tantalum Alkylamide During Vapor Deposition Processes

“…While this NDIR gas analyzer was specifically tested for PDMAT and DMA, it is suitable for characterizing the vapor delivery of other metal dimethylamido compounds that exhibit an absorption feature corresponding to the filter center wavelength of 10.56 μm (≈947 cm −1 ), e.g., tetrakis(dimethylamido) titanium (TDMAT) with a feature in the ≈943 cm −1 to ≈950 cm −1 range, 15–18,27,33,37–41 tetrakis(dimethylamido) hafnium with a feature in the ≈942 cm −1 to ≈943 cm −1 range, 27,42 tetrakis(dimethylamido) vanadium with a feature reported at 944 cm −1 , 27 pentakis(dimethylamido) niobium with a feature reported at 938 cm −1 , 27 and tetrakis(dimethylamido) zirconium with a feature in the ≈933 cm −1 to ≈936 cm −1 range, 27,43 although the NDIR analyzer performance would presumably degrade as the peak absorbance deviated from the filter center wavelength. The DMA 14.03 μm center wavelength filter is also suitable for monitoring the amines corresponding to the hydrogenated ligands of metal ethylmethylamide and metal diethylamide compounds: the N–H bending mode in methylethylamine is observed in the ≈724 cm −1 to ≈725 cm −1 range, 31,44 while that of diethylamine is observed in the ≈716 cm −1 to ≈721 cm −1 range.…”

“…The DMA molar absorptivity was determined previously with a commercial FT-IR spectrometer at 1 cm À1 spectral resolution using a liquid nitrogen-cooled wideband mercury cadmium telluride (MCT) detector. 33 The PDMAT molar absorptivity was determined in a similar manner with a 12.4 cm path length vacuum optical cell and a commercial FT-IR spectrometer at 1 cm À1 spectral resolution using a deuterated triglycine sulfate detector (DTGS) and using a heated capacitance diaphragm gauge (CDG) with a 1 kPa full scale range to measure the optical cell pressure. The PDMAT spectrum was not corrected for sample emissivity.…”

“…The NDIR gas analyzer optical response as a function of analyte pressure was determined separately from the flow cell using a 12.693 cm long path length vacuum optical cell (nominally identical to that used to measure the reference spectra 33 ) configured with a 1.33 kPa full scale range CDG (with a 100 C heater set point).…”

Measurements of Metal Alkylamide Density during Atomic Layer Deposition Using a Mid-Infrared Light-Emitting Diode (LED) Source

“…Dimethylamine (DMA), (CH 3 ) 2 NH, is a reaction product that is often observed in deposition processes involving TDMAT. 18–21 Dimethylamine exhibits IR-active CH-stretching modes, 22 and therefore, the presence of DMA is a significant potential interference for this technique. Dimethylamine can be produced both as a thermal decomposition product in a TDMAT ampoule and as a deposition reaction product in the deposition chamber.…”