Temperature compensated fused silica resonators using embedded nickel-refilled trenches

This paper reports a new fabrication process that utilizes nickel-refilled trenches to achieve passive temperature compensation in fused silica. Using this scheme, piezoelectrically actuated fused silica resonators are demonstrated with a temperature coefficient of frequency (TCF) of +50.28 ppm/K (reduced from +77.65 ppm/K) and quality factors of over 5,000. Additionally, a higher frequency mode at 16 MHz shows a TCF of +21.84 ppm/K (reduced from +71.94 ppm/K). This compensation method can be extended to actuate a compensated and an uncompensated mode of the same device, allowing for a temperature-stable dual-mode frequency reference. This is the first time that passive temperature compensation has been shown for fused silica micro-mechanical resonators.