Patent ID: 9676617
Date: 2017-06-13
CPC Classifications: B06B,B81B,B81C,H01L,H02N,H03H,H04R,Y10T

Claim:
1. A method for a capacitive micromachined ultrasound transducer (cMUT), the method comprising: growing and patterning a diffusion barrier layer over a substrate, the diffusion barrier layer having a first area and a second area, the diffusion barrier layer in the first area being patterned to allow a greater level of diffusion penetration of a gas therethrough to form a thermal oxide than a level of diffusion penetration of the gas to form the thermal oxide allowed by the patterning of the diffusion barrier layer at the second area; performing a diffusion process over the diffusion barrier layer to form the thermal oxide to reach a first depth into the substrate below the first area; forming an anchor using the thermal oxide, such that the anchor has a lower portion below a major surface of the substrate and an upper portion above the major surface of the substrate; and forming a membrane layer over the anchor and the substrate, wherein the substrate has a first electrode, the membrane layer has a second electrode opposing the first electrode to define a gap therebetween, and at least one of the membrane layer and the substrate includes a flexible layer, such that the first electrode and the second electrode are movable relative to each other to cause a change of the gap.