Coating processes – Measuring – testing – or indicating – Thickness or uniformity of thickness determined
Patent
1990-03-30
1992-05-12
Beck, Shrive
Coating processes
Measuring, testing, or indicating
Thickness or uniformity of thickness determined
427100, C23C 2600
Patent
active
051126427
ABSTRACT:
The thickness and rate of growth of a deposited film is monitored using a piezoelectric crystal sensor such as an AT-cut plano-convex crystal. The frequencies of the fundamental frequency and another resonance mode are measured prior to deposition, and the change of these two frequencies is monitored during deposition. The areal mass density of the deposited material is determined from these two resonance frequencies for the uncoated quartz crystal and for the crystal during deposition. A frequency generator provides accurate sweeps of frequency which are applied to the crystal, and the crystal response is supplied to a phase detector to identify the positions of the resonance frequencies. The acoustic impedance ratio Z of the deposited material relative to the fresh crystal is computed from the resonance frequencies for the coated and uncoated crystal, by applying the modal equations for AT-cut plano-convex quartz crystal and Lu-Lewis relation. From the frequency shifts and acoustic impedance ratio, and areal mass density can be calculated. The same crystal can be used to control the growth rate of several successive layers.
REFERENCES:
patent: 3528851 (1970-09-01), Koneval
patent: 3655429 (1972-04-01), Deklerk
patent: 4205117 (1980-05-01), Nishiyama
patent: 4343827 (1982-08-01), Thompson
patent: 4484382 (1984-11-01), Kawashima
patent: 4676993 (1987-06-01), Roberts
patent: 4792463 (1988-12-01), Okada
patent: 4817430 (1989-05-01), Benes et al.
patent: 4870313 (1989-09-01), Hirama
Anderson, Spurious Modes in AT-Cut Quartz Crystals, Proceedings of the 17th Annual Freq. Control Symposium, 1963-pp. 312-313.
Sauerbrey, Investigation of Resonant Modes of Planoconvex AT-Plates, Proceedings of the 21st Annual Freq. Control, 1967, pp. 63-71.
V. Bottom, Introduction to Quartz Crystal Unit Design Van Nostrand, 1982-p. 75.
D. Salt, Hy-Q Handbook of Quartz Crystal Device VanNostrand, 1988-pp. 157 & 51.
Benes, et al., Enhanced Composite Resonator Analysis, Proceedings of the 39th Annual Symposium on Freq. Control pp. 1-15.
Nowotny, et al., General One-dimensional Treatment of the Layered Piezoelectric Resonator with two Electrodes, J. Acoust. Soc. Am 82 (2), Aug. 1987, pp. 513-521.
Benes, et al., Process in Monitoring Thin Film Thickness by Use of Quartz Crystals, Thin Solid Films 174 (1989) pp. 307-314.
M. Schmid, et al., A Computer-Controlled System for the Measurement of Complete Admittance Spectra of Piezoelectric Resonators-Meas. Sci. Tech. 1 (1990).
J. de Klak "C Axis Flipping, For Multilayer Piezoelectric Thin-Film Transducers" Applied Physics Letters, vol. 13, No. 3, Aug. 1, 1968, pp. 102-104.
Tierston & Smythe An Analysis of Contured Crystal Resonators Operating in Overtones of Coupled Thickness Shear and Thickness Twist J. Acoust. Soc. Am. 65(6), Jun. 1979-1455-1460.
Benes Improved Quartz Crystal Microbalance Technique J. Appl. Phys. 56(3) Aug. 1984 608-626.
Beck Shrive
Dang Vi Duong
Leybold Inficon Inc.
LandOfFree
Measuring and controlling deposition on a piezoelectric monitor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Measuring and controlling deposition on a piezoelectric monitor , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Measuring and controlling deposition on a piezoelectric monitor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2425813