Increased dissipation from distributed etch holes in a lateral breathing mode silicon micromechanical resonator

Etch holes are commonly used design features when fabricating silicon-on-insulator micromechanical resonators to realize free standing structures. This paper shows that including etch-holes in a square-extensional mode resonator results in marked reduction of quality factor (Q) by 75%. The cause of this drop is explained by our finite element model used to theoretically estimate Q. These theoretical estimates agree well with measurement results. Our analyses show that anchor loss is dominant in a plain structure while etch holes increase thermoelastic damping to the point where both dissipation factors become comparable in determining the actual Q.