Effect of etch holes on quality factor of bulk-mode micromechanical resonators

A report is presented, for the first time, on the effect of release etch holes on the quality factors of bulk-mode micromechanical resonators. The bulk resonators were operated in the Lame mode with frequencies around 6 MHz. Periodic 10 mu m square etch holes with 30 mu m spacing were placed at various locations on the surface of the resonator. A study on five such identical resonators with etch holes at various locations conclusively shows that etch holes decrease the quality factors by more than an order of magnitude from 1.67 million to 116 000 owing to two main energy loss mechanisms. Furthermore, it is demonstrated that the quality factor depends on the location of etch holes on the resonator.