Acoustic wave devices using artificial twin quartz plates

We present a technique to form an artificial twin quartz plate with an arbitrary pattern. After depositing a thin metal film of chromium, nickel or Nichrome on a quartz plate, the substrate is thermally treated. Thermal treatment at 550–560° C causes x-axis inversion for the quartz under the film while the x -axis inversion does not occur in other areas. The x -axis inversion phenomenon depends on the cut angle of the substrate, film material and film thickness. Applications of the x -axis inversion phenomenon to bulk acoustic wave devices are proposed. One is the configuration of an AT-cut resonator with a temperature sensor on chip. The other is the temperature compensation technique for AT-cut resonators. Experimental results suggest the possibility for these applications.