Abstract
To improve the thickness uniformity of thin quartz crystal wafer, new machining process applying numerically controlled plasma CVM was developed. In this process, thickness distribution of the quartz crystal wafer was improved by two-step correction process which utilizes both a cylindrical shaped rotary electrode and a pipe electrode. Firstly, long spatial wavelength component of the thickness error is corrected by using the rotary electrode. And secondly, short wavelength component is corrected by using small size pipe electrode. By adopting the two-step correcting process, thickness distribution of an AT cut wafer was improved from 108 nm (p-v : peak to valley) to 14 nm (p-v). And the spurious mode in the resonance curve was reduced by improving the parallelism of the quartz crystal wafer.
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