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Non-dispersive infrared gas analyzer for partial pressure measurements of a tantalum alkylamide during vapor deposition processes

Published

Author(s)

James E. Maslar, William A. Kimes, Brent A. Sperling, Ravindra K. Kanjolia

Abstract

A non-dispersive infrared (NDIR) gas analyzer was demonstrated for investigating metal alkylamide precursor delivery for microelectronics vapor deposition processes. The NDIR analyzer was designed to simultaneously measure the partial pressure of pentakis(dimethylamido) tantalum (PDMAT), a metal precursor employed in high volume manufacturing (HVM) vapor deposition processes to deposit tantalum nitride, and dimethylamine (DMA), the primary decomposition product of PDMAT at typical delivery conditions for these applications. This sensor was based on direct absorption of PDMAT and DMA in the fingerprint spectral region. The NDIR analyzer optical response was calibrated by measuring absorbance as a function of DMA and PDMAT density. The difference between the mass of material removed from the ampoule during flow tests as measured gravimetrically and as determined optically, by calculating flow rates from the NDIR analyzer measurements, was only ≈ 2 %, further validating the calibration method. The minimum detectable molecular densities for PDMAT and DMA were ≈ 2 x 1013 cm-3 and ≈ 5 x 1014 cm-3, respectively (with no signal averaging and for a sampling rate of 200 Hz), and the corresponding partial pressures were ≈ 0.1 Pa and ≈ 2 Pa for PDMAT and DMA, respectively (for an optical flow cell temperature of 93 °C). PDMAT could be detected at all conditions of this investigation and likely the majority of conditions relevant to HVM tantalum nitride deposition. DMA was not detected at all conditions in this study, because of a lower NDIR analyzer sensitivity to DMA compared to PDMAT and because conditions of this study were selected to minimize DMA production. While this NDIR gas analyzer was specifically developed for PDMAT and DMA, it is suitable for characterizing the vapor delivery of other metal alkylamide precursors and the corresponding amine decomposition products, although in the case of some metal alkylamides a different bandpass filter would be required.
Citation
Applied Spectroscopy
Volume
74
Issue
10

Keywords

ALD, atomic layer deposition, chemical vapor deposition, CVD, nfrared absorption, non-dispersive infrared gas analyzer, NDIR, PDMAT, pentakis(dimethylamido) tantalum

Citation

Maslar, J. , Kimes, W. , Sperling, B. and Kanjolia, R. (2020), Non-dispersive infrared gas analyzer for partial pressure measurements of a tantalum alkylamide during vapor deposition processes, Applied Spectroscopy, [online], https://doi.org/10.1177/0003702819885182 (Accessed December 5, 2022)
Created August 24, 2020, Updated September 8, 2022