A method of fabricating an ultrasound device, the method comprising: providing a first wafer having a first silicon device layer with a first thickness and a dielectric layer with a second thickness in contact with the first silicon device layer , providing a second wafer having a second silicon device layer , forming, in the first wafer , a plurality of cavities by completely etching through the second thickness of the dielectric layer and by partially etching through the first thickness of the first silicon device layer ; and bonding the second wafer with the first wafer so that the plurality of cavities are disposed between the first silicon device layer and the second silicon device layer , wherein forming, in the first wafer , a plurality of cavities comprises, for each one of the plurality of cavities : forming an outer cavity portion by completely etching through the second thickness of the dielectric layer and partially etching through the first thickness of the first silicon device layer ; and forming an inner cavity portion by etching portions of the dielectric layer bounded by the outer cavity portion down to the surface of the first silicon device layer , so that the outer cavity portion is adjacent to and surrounds the inner cavity portion , the outer cavity portion having a greater depth than the inner cavity portion , and the first silicon device layer is configured as a membrane of the plurality of cavities of the ultrasound device. providing a first wafer having a first silicon device layer with a first thickness and a dielectric layer with a second thickness in contact with the first silicon device layer , providing a second wafer having a second silicon device layer , forming, in the first wafer , a plurality of cavities by completely etching through the second thickness of the dielectric layer and by partially etching through the first thickness of the first silicon device layer ; and bonding the second wafer with the first wafer so that the plurality of cavities are disposed between the first silicon device layer and the second silicon device layer , wherein forming, in the first wafer , a plurality of cavities comprises, for each one of the plurality of cavities : forming an outer cavity portion by completely etching through the second thickness of the dielectric layer and partially etching through the first thickness of the first silicon device layer ; and forming an inner cavity portion by etching portions of the dielectric layer bounded by the outer cavity portion down to the surface of the first silicon device layer , so that the outer cavity portion is adjacent to and surrounds the inner cavity portion , the outer cavity portion having a greater depth than the inner cavity portion , and forming an outer cavity portion by completely etching through the second thickness of the dielectric layer and partially etching through the first thickness of the first silicon device layer ; and forming an inner cavity portion by etching portions of the dielectric layer bounded by the outer cavity portion down to the surface of the first silicon device layer , so that the outer cavity portion is adjacent to and surrounds the inner cavity portion , the outer cavity portion having a greater depth than the inner cavity portion , and the first silicon device layer is configured as a membrane of the plurality of cavities of the ultrasound device. <EOS>