Patent ID: 7615834
Filing Date: 2009-11-10
Classification: B06B,B81B,H01L

Abstract:
1. A capacitive micro-machined ultrasonic transducer as comprising: a substrate; a support having a base in contact with the substrate, and a wall extending away from the base to a top; and a membrane having an upper surface and a lower surface and extending in a lateral dimension parallel to the support and between the support wall to create a cavity defined by the substrate, the wall, and the membrane lower surface and a defining a gap between the substrate and the membrane; the membrane having a non-uniform membrane thickness extending in a direction orthogonal to the membrane surface, the non-uniformity in the membrane thickness resulting from at least one of: (i) a thickening on the upper surface of the membrane outside of the cavity, (ii) a thickening on the lower surface of the membrane inside of the cavity, (iii) a trench on an upper surface of the membrane, (iv) a trench on a lower surface of the membrane, and (v) any combination of two or more of these; the device includes at least one trench formed into the membrane and at least one additional thickened membrane portion; and wherein at least one of: (a) the first thickened portion and the second thickened portion overlie or substantially overlie each other on opposite surfaces of the membrane, (b) the first thickened portion and the second thickened portion do not overlie or substantially overlie each other on opposite surfaces of the membrane, and (c) the first thickened portion and the second thickened portion partially overlie each other on opposite surfaces of the membrane.