| 摘要 |
<p>A lower electrode (4a) is formed over a semiconductor substrate (1S) via an insulator film (2), first (5) and second (7) insulator films are formed to cover the lower electrode, an upper electrode (20) is formed over the second insulator film (7), third to fifth insulator films (9,11,13) are formed to cover the upper electrode (20) and a void (VR) is formed between the first and second insulator films (5,7) between the lower and upper electrodes (4a,20). An ultrasonic transducer comprises the lower electrode (4a), the first insulator film (5), the void (VR), the second insulator film (7) and the upper electrode (20). A portion of the first insulator film (5) contacting with the lower electrode (4a) is made of silicon oxide (5a,5c), a portion of the second insulator film (7) contacting with the upper electrode (20) is made of silicon oxide and the first or second insulator film (5,7) includes a silicon nitride film (5b) positioned between the upper and lower electrodes (4a,20) and not in contact with the upper and lower electrodes (4a,20).</p> |
