Process for manufacturing a thin-film piezoelectric microelectromechanical structure having improved electrical characteristics

A process for manufacturing a piezoelectric microelectromechanical structure, comprising:

• forming a piezoelectric stack having a main extension in a horizontal plane and a variable section in a plane transverse to said horizontal plane;
• wherein forming the piezoelectric stack comprises forming, stacked on one another:
• a bottom-electrode region;
• a piezoelectric material region, constituted by a lead zirconate titanate (PZT) film, arranged on the bottom-electrode region;
• and a top-electrode region arranged on the piezoelectric material region;
• wherein the piezoelectric material region has, as a result of said variable section, a first thickness along a vertical axis transverse to said horizontal plane at a first area, and a second thickness along said vertical axis at a second area, the second thickness being smaller than the first thickness;
• forming a patterned structure having respective projections and respective recesses over an active layer of a wafer of semiconductor material;
• wherein forming the piezoelectric stack comprises forming said bottom-electrode region on said patterned structure with said piezoelectric material region having projections with the first thickness that jointly define the first area, and recesses with the second thickness that jointly define the second area;
• and
• wherein said piezoelectric stack is arranged on a supporting element configured to undergo deformation along the vertical axis via a piezoelectric effect, said supporting element suspended above an underlying opening and separated from the piezoelectric stack by a dielectric region interposed between said supporting element and the bottom-electrode region;
• wherein said patterned structure is defined by said dielectric region.