Patent ID: 11944998
Assignee: KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY
Field: Micro-structural and nano-technology (Chemistry)
Classification: CPC B | IPC B

Claim 0:
1. A method of fabricating a capacitive micromachined ultrasonic transducer (CMUT), the method comprising:
forming, on a semiconductor substrate doped as a first conductive type, a first region implanted with impurity ions at a first average concentration and a second region implanted with no impurity ions or implanted with the impurity ions at a second average concentration lower than the first average concentration, wherein the impurity ions are of a second conductive type opposite to the first conductive type, and include at least one of As ion, P ion, and BF2 ion;
forming an insulating layer by oxidizing the semiconductor substrate, the insulating layer including a first oxide layer having a first thickness on at least a part of the first region and a second oxide layer having a second thickness smaller than the first thickness on at least a part of the second region; and
forming a membrane layer on the insulating layer such that a gap is defined between the second oxide layer and the membrane layer,
wherein in the forming of the insulation layer, the first oxide layer and the second oxide layer are simultaneously formed by one oxidation process to have different thicknesses from each other while the first region has a relatively high implantation concentration and a faster oxidation rate than the second region, which has a relatively low implantation concentration.