A controllable wet-etching method to fabricate high-frequency ZnO ultrasonic arrays
Résumé
A controllable wet-chemical etching method is presented to fabricate thick-film ZnO-based ultrasonic transducer arrays. The wet-chemical etchant is NH4Cl aqueous solution with a concentration of 10 wt% and the etching rate is 60 nm/min at room temperature. A ZnO array is achieved due to a small ratio (0.25) of lateral etching to vertical etching. This novel etching method provides a possibility to acquire a pitch of a λ in a 300 MHz array.