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In-situ RF diagnostic for PECVD process control

Published online by Cambridge University Press:  10 February 2011

S. Raoux
Affiliation:
Applied Materials, 3225 Oakmead Village Drive, Santa Clara, CA 95054.
K. S. Liu
Affiliation:
Applied Materials, 3225 Oakmead Village Drive, Santa Clara, CA 95054.
X. Guo
Affiliation:
Applied Materials, 3225 Oakmead Village Drive, Santa Clara, CA 95054.
D. Silvetti
Affiliation:
Applied Materials, 3225 Oakmead Village Drive, Santa Clara, CA 95054.
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Abstract

The fabrication of advanced integrated circuits requires increased accuracy in process monitoring and active control. As higher production yields are required, the technology is moving from statistical process control to in-situ diagnostic techniques. A set of experiments was conducted to explore the feasibility of using radio frequency (RF) impedance probes to detect deviation of electrical characteristics of process chambers during wafer fabrication. A probe was integrated on a plasma-enhanced chemical vapor deposition (PECVD) chamber to explore the sensitivity of the reactor electrical characteristics on the events of process drift or input parameter variation. We measured RF the voltage, current and harmonics, the phase angle and the impedance magnitude for a capacitively coupled reactor. A single frequency (13.56MHz) process for depositing Si0 2 and a dual frequency (13.56MHz+35OkHz) process for Si3N4 deposition were characterized. We investigated the dependence of the RF signature and process parameters such as RF power, pressure, gas flow and electrode spacing. We observed that there is a correlation between the film properties (especially stress) and the plasma electrical characteristics. Furthermore, RF probes can be used to detect chamber malfunctions such as lost of RF ground or wafer-out-of-pocket events.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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