Inertial sensor, method of manufacturing inertial sensor, and inertial measurement unit
An inertial sensor includes: a substrate; an insulating film provided on a main surface of the substrate; a first semiconductor layer and a second semiconductor layer which are provided on an opposite-side surface of the insulating film from the substrate; a first oxide film provided on a first side surface of the first semiconductor layer on a second semiconductor layer side; a second oxide film provided on a second side surface of the second semiconductor layer on a first semiconductor layer side; a planarization insulating film provided above the first oxide film and the second oxide film and between the first oxide film and the second oxide film; and a wiring provided on the planarization insulating film and electrically coupled to the second semiconductor layer.
1 . An inertial sensor comprising:
a substrate;
an insulating film provided on a main surface of the substrate;
a first semiconductor layer and a second semiconductor layer which are provided on an opposite-side surface of the insulating film from the substrate;
a first oxide film provided on a first side surface of the first semiconductor layer on a second semiconductor layer side;
a second oxide film provided on a second side surface of the second semiconductor layer on a first semiconductor layer side;
a planarization insulating film provided above the first oxide film and the second oxide film and between the first oxide film and the second oxide film; and
a wiring provided on the planarization insulating film and electrically coupled to the second semiconductor layer, wherein
a trench portion is formed between the first semiconductor layer and the second semiconductor layer, and the trench portion is filled with a first sidewall oxide film formed on a first side surface of the first semiconductor layer facing the second semiconductor layer, and a second sidewall oxide film formed on a second side surface of the second semiconductor layer facing the first semiconductor layer,
the insulating film includes a thick film portion in which the film thickness of a region of the insulating film in contact with the trench portion is greater than a first film thickness of a first region of the insulating film in contact with the first semiconductor layer and a second film thickness of a second region of the insulating film in contact with the second semiconductor layer.
2 . The inertial sensor according to claim 1 , wherein
0<upper surface thickness t 1 of thermal oxide film<side surface thickness t 2 of thermal oxide film,
in which the side surface thickness t 2 of the thermal oxide film is a thickness of the first oxide film on the first side surface and a thickness of the second oxide film on the second side surface, and the upper surface thickness t 1 of the thermal oxide film is a thickness of an upper portion of the first oxide film and a thickness of an upper portion of the second oxide film.
3 . The inertial sensor according to claim 1 , wherein
a relative dielectric constant of the planarization insulating film is 3.9 or less.
4 . The inertial sensor according to claim 1 , wherein
the first semiconductor layer and the second semiconductor layer are made of single-crystal silicon, and the first oxide film and the second oxide film are made of thermal silicon oxide.
5 . The inertial sensor according to claim 1 , wherein
a gap surrounded by the insulating film, the first oxide film, and the second oxide film is formed.
6 . An inertial measurement unit comprising:
the inertial sensor according to claim 1 ; and
a control unit configured to control the inertial sensor.