Two different types of temperature-compensated film bulk acoustic resonators (FBARs) are designed, fabricated, and tested. One is formed by integrating FBAR with a surface-micro-machined air-gap capacitor, which passively reduces the FBAR's temperature coefficient of frequency (TCF) by about 40 ppm/°C at 2.8 GHz. With this approach, zero TCF would easily have been achieved if the FBARs were built on AlN rather than ZnO. The other type of temperature compensated FBAR is built on a surface-micromachined SiO2 cantilever that is released by XeF2 vapor etching of silicon. The Al-ZnO-Al-SiO2 FBAR is measured to have a TCF of -0.45 ppm/°C (between 85 °C and 110 °C) at 4.4 GHz.
- Air-gap capacitor
- Film bulk acoustic resonators (FBARs)
- Surface micromaching
- Temperature compensation
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering