Method of fabricating suspended microstructures

A method of fabricating a suspended platform on a bonded-substrate that includes a platform substrate that is bonded to a base substrate, comprising:

• forming a dielectric layer on a support surface of the base substrate;
• patterning an interface surface of the dielectric layer to define a well feature thereon;
• etching the well feature until a well having a preselected depth that leaves a thin protective layer of the dielectric layer covering the support surface is formed;
• bonding the base and platform substrates to each other by urging the interface surface into contact with a mounting surface of the platform substrate and annealing the base and platform substrates to fusion bond the interface surface with the mounting surface;
• thinning the platform substrate to form a membrane over a sealed cavity defined by the well and the mounting surface;
• patterning the membrane to define a flexture feature and a platform feature;
• etching the flexture and platform features to form a plurality of trenches that extend through the membrane to the sealed cavity and define a suspended platform and a flexure;
• and
• applying a selective etch material to remove the dielectric layer from beneath the suspended platform and the flexure.