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Electrode Configuration On Quartz Resonators for Use As Rate Monitors in Electrolytic Depositions

IP.com Disclosure Number: IPCOM000041087D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Gluck, T: AUTHOR [+3]

Abstract

A quartz crystal is shown which is used as a rate monitor in electrolytic deposition systems, and the electrodes are asymmetrical to minimize sensitivity to non-uniform deposition.

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Electrode Configuration On Quartz Resonators for Use As Rate Monitors in Electrolytic Depositions

A quartz crystal is shown which is used as a rate monitor in electrolytic deposition systems, and the electrodes are asymmetrical to minimize sensitivity to non-uniform deposition.

Quartz crystals which have electrodes opposing each other on opposite faces of the quartz have been used to measure the mass or the thickness of deposits in electrolytic deposition systems. Acoustic shear waves are generated piezoelectrically in the quartz region contained between the electrodes, and are sustained under resonant conditions. This resonant frequency decreases with increased deposition and is used to measure the mass or thickness of the deposit. In the case of symmetrical electrodes, the frequency is related to some average film thickness since the whole electrode is acoustically excited. However, it is well known that enhanced plating occurs in regions of high current density. Such an effect will occur along the edges of a conducting surface so that a film thicker around the edges than in the central region results. This leads to an erroneous reading when using symmetrical electrodes on a quartz crystal.

As shown in the Figure, the electrodes in the present design are asymmetrical to minimize sensitivity to non-uniform deposition. The film is to be deposited on the larger electrode 2 which is on the opposite face of the quartz crystal 1 from the smaller electrode 3. Since th...