Semiconductor physical-quantity sensor and method for manufacturing same

A method for manufacturing a semiconductor physical-quantity sensor comprising a semiconductor substrate and a movable portion of a beam structure composed of a thin film, the method comprising the steps of:

• forming a sacrificial layer having a surface irregularities portion on a surface of the semiconductor substrate in a region between the semiconductor substrate and a movable portion location;
• forming a movable portion thin film on the sacrificial layer;
• and
• removing the sacrificial layer beneath the movable portion thin film by etching to thereby form a movable portion of the beam structure whose underside has an irregularities portion formed by the surface irregularities portion of the sacrificial layer.

A method for manufacturing a semiconductor physical-quantity sensor comprising a semiconductor substrate and a movable portion of a beam structure composed of a thin film, the method comprising the steps of:

• forming an underlying film having an irregularities portion on a surface of the semiconductor substrate in a region between the semiconductor substrate and a movable portion region;
• forming, on the underlying film, a sacrificial layer having a surface irregularities portion that corresponds to a part of the irregularities portion of the underlying layer;
• forming a movable portion thin film on the sacrificial layer;
• and
• removing the sacrificial layer beneath the movable portion thin film by etching to thereby form the movable portion of the beam structure, the movable portion including an irregularities portion on an underside thereof formed by the surface irregularities portion of the sacrificial layer.

A semiconductor physical-quantity sensor comprising:

• a semiconductor substrate;
• a movable portion of a beam structure that is composed of a thin film and disposed over the semiconductor substrate with a cavity interposed therebetween and is displaceable in accordance with an action of a physical quantity;
• and
• an underlying film that has an irregularities surface and has conductivity and that is disposed on a surface of the semiconductor substrate in a region between the semiconductor substrate and the movable portion, wherein the underlying film is electrically connected to the movable portion.

A method of manufacturing a semiconductor physical-quantity sensor on a semiconductor substrate, comprising:

• depositing on the substrate a surface film that includes an irregular surface region;
• depositing a sacrificial layer on the surface film;
• depositing a movable sensor component film on the sacrificial layer;
• and
• removing the sacrificial layer beneath the movable sensor component film, by etching, to form a movable sensor component over the irregular surface region of the surface film.

A semiconductor physical-quantity sensor comprising:

• a semiconductor substrate;
• a movable portion of a beam structure that is composed of a thin film and that is disposed over the semiconductor substrate with a cavity interposed therebetween, and is displaceable in accordance with an action of a physical quantity, the movable portion having an underside with an irregularities surface that opposes the semiconductor substrate;
• and
• an underlying film that has conductivity and that is disposed on a surface of the semiconductor substrate in a region between the semiconductor substrate and the movable portion, wherein the underlying film is electrically connected to the movable portion.