The manufacturing yield of semiconductor devices (CMUTs) is improved. Before a polyimide film serving as a protective film is formed, a membrane is repeatedly vibrated to evaluate the breakdown voltage between an upper electrode and a lower electrode, and the upper electrode of a defective CMUT cell whose breakdown voltage between the upper electrode and the lower electrode is reduced due to the repeated vibrations of the membrane is removed in advance to cut off the electrical connection with other normal CMUT cells. By this means, in a block RB or a channel RCH including the recovered CMUT cell RC, reduction in the breakdown voltage between the upper electrode and the lower electrode after the repeated vibrations of the membrane is prevented.
