Bi- and three-dimensional prediction of etching shapes in quartz micromachined structures

The anisotropic etching behavior of quartz crystal in ammonium bifluoride solution was studied and analyzed according to the tensorial model of dissolution. The dissolution slowness surface was determined from experiments. Two-dimensional and three-dimensional graphical simulations were performed, and the adequacy of the proposed slowness surface was considered. Numerical procedures have been developed to derive etching shapes encountered in conventional crystal etching (two-dimensional simulation) and in localized crystal dissolution (three-dimensional simulation for photolithography techniques). It is concluded the dissolution shapes derived from the proposed slowness surface do not depart very much from experimental shapes