A piezoelectric microelectromechanical structure (10), provided with a piezoelectric layer structure (11) having a main extension in a horizontal plane (xy) and a variable cross-section in a plane (xz) transverse to the horizontal plane, comprises a bottom electrode (12), a piezoelectric material (14) constituted by a PZT film arranged on the bottom electrode, and a top electrode (16) arranged on the piezoelectric material, wherein the piezoelectric material has a first thickness (w1) along a vertical axis (z) at a first area (14') and a second thickness (w2) along the vertical axis (z) at a second area (14"), the second thickness being smaller than the first thickness. A corresponding manufacturing process is also disclosed.