Rounded and curved integrated tethers for quartz resonators
A piezoelectric quartz shear-mode resonator includes plasma etched quartz tethers, each including a mount. The tethers are for mounting the resonator to a semiconductor substrate for the purpose of isolating the thermally-induced stress from the mounts from the active resonating region, wherein the quartz tethers have rounded corners.
1. A piezoelectric quartz shear-mode resonator comprising quartz isolation tethers, each comprising a mount for mounting to a semiconductor substrate, wherein the quartz tethers each have at least one rounded corner.
2. The quartz shear-mode resonator of claim 1 wherein:
the respective mounts are coupled to corresponding first sections of the isolation tethers by rounded outer corners and inner corners;
the respective first sections are coupled through a right angle to corresponding second sections by a rounded outer corner and a rounded inner corner;
the respective second sections are coupled through a right angle to corresponding third sections by rounded outer corners and inner corners; and
the respective third sections are coupled to the resonator by an rounded inner corner; wherein
the respective isolation tethers form a straight line between the inner corners of the third sections.
3. The quartz shear-mode resonator of claim 1 wherein:
the respective mounts are coupled to corresponding first sections by rounded outer corners and inner corners;
the respective first sections are coupled through a right angle to corresponding second sections by a rounded outer corner and a rounded inner corner; and
the respective second sections are coupled through a right angle to corresponding third sections by rounded outer corners and inner corners; and
the respective third sections are coupled to the resonator by a rounded inner corner; wherein
the respective isolation tethers form a continuous curve between the rounded outer and inner corners of the second sections.
4. The quartz shear-mode resonator of claim 1 wherein:
the respective mounts are coupled to corresponding first sections by rounded outer corners and inner corners;
the respective first sections are coupled through a right angle to corresponding second sections by a rounded outer corner and a rounded inner corner;
the respective second sections are coupled through right angles to corresponding third sections by rounded outer and inner corners;
the respective third sections are coupled to the resonator by a rounded inner corner; wherein
the respective isolation tethers form a continuous curve between the inner corners of the third section.
5. The quartz shear-mode resonator of claim 1 wherein:
the resonator is round or elliptical;
the isolation tethers are conformally wrapped around the resonator, wherein:
the respective mounts are coupled through a right angle to corresponding first sections of the tethers by rounded outer corners and inner corners;
the respective first sections are coupled through substantially right angles to corresponding quasi-circular second sections by rounded outer corners and inner corners; and
the respective second sections are coupled to the resonator by corresponding rounded inner corners; wherein
the respective isolation tethers form a substantially straight line between the inner corners of the third section.
6. The quartz shear-mode resonator of claim 1 wherein the quartz isolation tethers are plasma etched.
7. The quartz shear-mode resonator of claim 1 wherein the quartz isolation tethers are rounded or quasi-circular.
8. The quartz shear-mode resonator of claim 1 wherein the lateral width of the quartz isolation tethers is varied along its length.
9. The quartz shear-mode resonator of claim 1 wherein two sets of rounded or quasi-circular isolation tethers are attached to opposite sides of the resonator to minimize vibrational-induced strain in the resonator.
10. The quartz shear-mode resonator of claim 1 wherein the resonator is bonded to the semiconductor substrate with a metallic solder in the mount regions.
11. The quartz shear-mode resonator of claim 1 , wherein the quartz shear-mode resonator operates with its fundamental mode in the VHF or UHF ranges.
12. The quartz shear-mode resonator of claim 1 wherein the quartz is composed of AT or SC-cut material.