A 100-MHz ultrasonic transducer array using ZnO thin films

摘要: A 100-MHz ultrasonic linear transducer array made from a piezoelectric zinc oxide thin film on sapphire substrate was developed and evaluated. Epitaxial, high-acoustic quality 10-/spl mu/m-thick ZnO layers were produced by rf-magnetron sputter deposition onto (111)-oriented gold (with chromium adhesion layer) that vacuum-evaporated (0001) surface. We found that, in well-oriented growth of gold, it is important to control the sublayer thickness (less than 5 nm). An constructed photolithography with an appropriate etch. V-shaped grooves between adjacent elements formed using anisotropic etchant (HCl HNO/sub 3/-based) preferentially etched c-plane ZnO. Typical 90 /spl mu/m wide, 3.2 mm long, 10 thick, pitch typically 100 mu/m. Our fine uniform resulted response individual throughout array. For 32-element array, ultrasound beam azimuth plane water could be electronically focused MHz range obtain half-amplitude width 60 at focal depth, agreeing well theoretical predictions. Besides use demonstrated this present transducer, films should also lead fabrication various other kinds transducers can operate high frequencies provide opportunities for miniaturizing making integrated devices. >