Designed to drive a mirror surface to change a reflection path taken by light depending on its angle of rotation, a mirror device has so far been used for, e.g., optical equipments harnessing laser such as printers, copiers, displays, and projectors. The mirror surface of the mirror device is driven in an electrostatic drive mode using electrostatic force, a piezoelectric drive mode utilizing a piezoelectric element, and an electromagnetic drive mode using electromagnetic force (JP(A)'s 2001-13443, 2002-311376 and 2003-15064).
Of prior art mirror devices, a piezoelectric mirror device of the piezoelectric drive mode has an advantage of being higher in driving power than those of other drive modes. For instance, it has been fabricated by means of an MEMS (Micro-Electro-Mechanical systems), with a mirror portion formed by etching an SOI substrate and a mirror support portion for that mirror portion in a rotatable manner.
However, a problem with the conventional piezoelectric mirror device is that the amount of displacement of the mirror portion is limited, because the mirror support portion is made of a silicon layer (Si) of high rigidity (having a Young's modulus of 166 GPa). For the fabrication of the mirror support portion or the like, it is required to make use of an SOI substrate having a silicon oxide that provides an etching stopper; that SOI substrate costs much, placing some limitations on fabrication cost reductions.