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The use of quartz crystals (often called quartz crystal microbalances, or QC Ms) to monitor the deposition of thin films by vacuum processes has been an industry norm since the late 1960's. By measuring the resonance frequency of an oscillating crystal, one can determine the thickness of a metal or dielectric coating to within 1 Angstrom. This has proven to be an invaluable tool for process control and manufacture of optical and solid state electronic devices.
Due to its frequency-temperature behavior, however, quartz is limited to operating temperatures of 100 º C or less, and in most cases, must be water cooled to insure accurate and reproducible readings. Unfortunately, many advanced thin film coating processes operate in significantly hotter environments, including chemical vapor deposition (CVD), Atomic Layer Deposition (ALD) and electron beam evaporation. In such cases, the performance of the quartz crystal is simply inadequate.
With the invention of single crystal gallium
orthophosphate, or GaPO4 , this temperature limit had been significantly raised, to a practical operating ceiling of 800 º C. This opens up new possibilities for thin film research and process control.
Please visit our distribution partner and application specialist Virginia Beach Sensors for technical or commercial information on our high performance resonators or contact our specialists.
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