Patent ID: 7540192

Claim:
A method for manufacturing a physical quantity sensor, which includes a movable portion, a support portion and an optical part, wherein the movable portion is movable in a predetermined direction in accordance with a physical quantity applied to the sensor, wherein the movable portion is movably supported on the support portion, wherein the optical part irradiates a light to the movable portion, the light emitted from an external light emitting device and entered into the optical part, and wherein the physical quantity is detected on the basis of detection of the light reflected on the movable portion, the detection performed by an external light detector, the method comprising steps of: etching a silicon substrate so that a movable-portion-to-be-formed portion, a support-portion-to-be-formed portion, and an optical-part-to-be-formed portion are formed on the silicon substrate, wherein the movable-portion-to-be-formed portion provides the movable portion, the support-portion-to-be-formed portion provides the support portion, and the optical-part-to-be-formed portion provides the optical part, and wherein the optical-part-to-be-formed portion includes a plurality of columns, which are disposed in parallel each other and have a trench between two neighboring columns; oxidizing the optical-part-to-be-formed portion so that each column changes to a silicon oxide column and the trench is filled with a silicon oxide layer; and removing a part of the movable-portion-to-be-formed portion connecting to the silicon substrate so that the movable portion is separated from the silicon substrate and the movable portion is movably supported on the support portion.