US 12,145,838 B2
CMUT transducer with motion-stopping structure and CMUT transducer forming method
Cyril Meynier, Tours (FR); Dominique Gross, Tours (FR); and Nicolas Senegond, Tours (FR)
Assigned to VERMON SA, Tours (FR)
Appl. No. 17/637,125
Filed by VERMON SA, Tours (FR)
PCT Filed Jul. 16, 2020, PCT No. PCT/IB2020/000624
§ 371(c)(1), (2) Date Feb. 22, 2022,
PCT Pub. No. WO2021/038288, PCT Pub. Date Mar. 4, 2021.
Claims priority of provisional application 62/894,259, filed on Aug. 30, 2019.
Prior Publication US 2022/0340410 A1, Oct. 27, 2022
Int. Cl. B81B 3/00 (2006.01); B06B 1/02 (2006.01); B81C 1/00 (2006.01); G01N 29/24 (2006.01)
CPC B81B 3/0021 (2013.01) [B06B 1/0292 (2013.01); B81C 1/00158 (2013.01); B81B 2201/0271 (2013.01); B81B 2203/0127 (2013.01); B81B 2203/0315 (2013.01); B81B 2203/04 (2013.01); B81C 2201/013 (2013.01); B81C 2201/0178 (2013.01); G01N 29/2406 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of manufacturing a CMUT transducer comprising:
a conductive or semiconductor substrate coated with a stack of one or a plurality of dielectric layers;
a cavity formed in said stack;
a conductive or semiconductor membrane suspended above the cavity;
at the bottom of the cavity, a conductive region in contact with the upper surface of the substrate, said conductive region being interrupted on a portion of the upper surface of the substrate; and
in the cavity, a stop structure made of a dielectric material localized on or above the area of interruption of the conductive region,
the method comprising the steps of:
a) forming a first dielectric layer on the upper surface of the substrate;
b) etching the first dielectric layer down the upper surface of the substrate to form a lower portion of the cavity of the transducer, while keeping in a central portion of the cavity a portion of the first dielectric layer forming the stop structure of the transducer;
c) depositing at the bottom of the cavity a conductive layer having a thickness smaller than that of the first dielectric layer, forming the conductive region of the transducer;
d) forming a second dielectric layer on a surface of a semiconductor layer arranged on a temporary support;
e) etching the second dielectric layer down to the surface of the semiconductor layer to form an upper portion of the cavity;
f) assembling the temporary support and the substrate by bonding of the surface of the first dielectric layer opposite to the substrate onto the surface of the second dielectric layer opposite to the semiconductor layer; and
g) removing the temporary support, while keeping above the cavity the semiconductor layer forming the membrane of the transducer.