Thickness metrology and end point control in W chemical vapor deposition process from SiH 4 / WF 6 using in situ mass spectrometry

• Published in: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Vol. 20; no. 6; pp. 2351 - 2360
• Main Authors: Xu, Y., Gougousi, T., Henn-Lecordier, L., Liu, Y., Cho, S., Rubloff, G. W.
• Format: Journal Article
• Language: English
• Published: 01-11-2002
• Subjects: W
• ISSN: 0734-211X; 1520-8567
• DOI: 10.1116/1.1520555

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 process). 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 (∼20% in this case) as often occurs in manufacturing processes, the thickness metrology (1.0%–1.5%) and control (∼1.5%–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.