In accordance with some embodiments, a method of forming an auto-focusing device is provided. The method includes forming a cantilever beam member. The cantilever beam member has a ring shape. The method further includes forming a piezoelectric member over the cantilever beam member. The method also includes forming a membrane over the cantilever beam member. The membrane has a first region and a second region. The first region has a planar surface, and the second region is located between the first region and an inner edge of the cantilever beam member and has a plurality of corrugation structures. In addition, the method includes applying a liquid optical medium over the membrane and sealing the liquid optical medium with a protection layer.