Real-time growth rate metrology for a tungsten chemical vapor deposition process by acoustic sensing

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

et al. 2002

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In-situ sensing using mass spectrometry and its use for run-to-run control on a W-CVD cluster tool AIP Conf.Process diagnostics and thickness metrology using in situ mass spectrometry for the chemical vapor deposition of W from H 2 / WF 6 Real-time, in situ chemical sensing has been applied to achieve reaction metrology and advanced process control in a low pressure tungsten chemical vapor deposition process based on WF 6 and SiH 4 reactants ͑silane reduction process͒. Using mass spectrometry as the sensor to detect both product generation (H 2 ) and reactant depletion (SiH 4 ) at wafer temperature of 200-250°C, these signals provided a direct real-time measurement of deposited film thickness with an uncertainty less than 2%, and this thickness metrology signal was employed to achieve real-time process end point control. When reactant conversion rates are sufficient ͑ϳ20% in this case͒ as often occurs in manufacturing processes, the thickness metrology ͑1.0%-1.5%͒ and control ͑ϳ1.5%-2.0%͒ accuracies are in the regime needed for meaningful application of advanced process control. Since the in situ sensor delivers a metrology signal in real time, real-time process control is achieved, enabling compensation for random process disturbances during an individual process cycle as well as for systematic wafer-to-wafer process drifts. These results are promising for manufacturing from the standpoints of metrology accuracy and application in real-time control.

Thickness metrology and end point control in W chemical vapor deposition process from SiH4/WF6 using in situ mass spectrometry

Gougousi

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

et al. 2002

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Real-time, in situ film thickness metrology in a 10 Torr W chemical vapor deposition process using an acoustic sensor

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

Kidder

Rubloff

et al. 2003

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Articles you may be interested inReal-time acoustic sensing and control of metalorganic chemical vapor deposition precursor concentrations delivered from solid phase sources In situ mass spectrometry in a 10 Torr W chemical vapor deposition process for film thickness metrology and real-time advanced process control Thickness metrology and end point control in W chemical vapor deposition process from SiH 4 / WF 6 using in situ mass spectrometry Process diagnostics and thickness metrology using in situ mass spectrometry for the chemical vapor deposition of W from H 2 / WF 6 Process gases were sampled from the outlet of a tungsten chemical vapor deposition ͑CVD͒ reactor into an Inficon Composer™ acoustic sensor for in situ chemical gas sensing and real-time film thickness metrology. Processes were carried out on an Ulvac W CVD cluster tool at 10 Torr from 340 to 400°C using a H 2 /WF 6 gas mixture. Sampled gases were compressed through a diaphragm pump up to 100 Torr as required for accurate measurements in the acoustic cell. The high depletion of the heavy WF 6 precursor ͑up to 30%͒ generated a significant variation of the average gas molecular weight and consequently of the mass-dependent resonant frequency measured by the acoustic sensor. The monitored signal was integrated over the process time, and the integrated area was correlated to the deposited W film thickness determined by ex situ measurements. The average error on this in-tool and real-time metrology was less than 1% over 30 wafers processed, either under fixed process conditions or while varying key process variables such as deposition time or temperature. A dynamic physically based simulator was also developed to validate the system response under different process conditions and demonstrate the fundamental understanding of this method. The metrology achieved represents a significant improvement over previously published data ͓L. Henn-Lecordier et al., J. Vac. Sci. Technol. A 19, 621 ͑2001͔͒ obtained on the same system but in the sub-Torr process pressure regime, where low depletion rates ͑around 3%͒ had limited the metrology to 7% error. With an error less than 1%, this in situ chemical sensing approach could be efficiently exploited for real-time course correction, e.g., using end-point film thickness control.

In situ mass spectrometry in a 10 Torr W chemical vapor deposition process for film thickness metrology and real-time advanced process control

Cho

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

Liu

et al. 2004

Articles you may be interested inIn situ chemical sensing in Al Ga N ∕ Ga N metal organic chemical vapor deposition process for precision film thickness metrology and real-time advanced process control J. Vac. Sci. Technol. B 23, 2007 (2005; 10.1116/1.2037707Real-time, in situ film thickness metrology in a 10 Torr W chemical vapor deposition process using an acoustic sensor J.Thickness metrology and end point control in W chemical vapor deposition process from SiH 4 / WF 6 using in situ mass spectrometry Process diagnostics and thickness metrology using in situ mass spectrometry for the chemical vapor deposition of W from H 2 / WF 6In situ mass spectrometric sensing has been implemented in a 10 Torr H 2 /WF 6 W chemical vapor deposition process as a real-time process and wafer state metrology tool. Dynamic sensing through the process cycle reveals HF byproduct generation as well as H 2 and WF 6 reactant depletion as real-time quantitative indicators of deposition on the wafer. Thickness metrology is achieved by integrating the HF byproduct signal through the process cycle and comparing it to post-process measurements of film weight. To evaluate the quantitative precision of this metrology, multiwafer runs have been performed under different sets of conditions: ͑1͒ fixed process conditions, ͑2͒ intentionally introduced run-to-run process temperature drift, and ͑3͒ run-to-run deposition time variation. These results demonstrate that real-time thickness metrology is achievable at a level of 1% or better in two application settings: ͑1͒ when an essentially fixed process recipe is employed, as in high-volume manufacturing; and ͑2͒ when more substantial changes in process recipe are explored, as in a development environment. In situ mass spectrometry presents an attractive option for real-time advanced process control with the prognosis for real-time course correction demonstrated here and its already established benefit to fault detection and classification.