Inertial sensor, method of manufacturing inertial sensor, and inertial measurement unit

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.