US 7,321,181 B2
Capacitive membrane ultrasonic transducers with reduced bulk wave generation and method
Butrus T. Khuri-Yakub, Palo Alto, Calif. (US); Arif S. Ergun, Mountain View, Calif. (US); and Goksen Yaralioglu, Mountain View, Calif. (US)
Assigned to The Board of Trustees of the Leland Stanford Junior University, Palo Alto, Calif. (US)
Filed on Apr. 04, 2005, as Appl. No. 11/98,863.
Claims priority of provisional application 60/560789, filed on Apr. 07, 2004.
Prior Publication US 2005/0236937 A1, Oct. 27, 2005
Int. Cl. H01L 41/08 (2006.01)
U.S. Cl. 310—320  [310/324; 310/334] 9 Claims
OG exemplary drawing
 
1. The method of suppressing bulk wave generation at the frequency of operation of a cMUT of the type which includes a membrane supported above a substrate which comprises configuring the substrate to suppress bulk wave generation at the operating frequency wherein the substrate is configured by photolithographically patterning and etching a defined periodic pattern of grooves on a back side of the substrate with the groove depth being one quarter the wavelength of the bulk waves to be suppressed.