Optical device production method

A method for manufacturing an optical device,

• the optical device comprising:
• a base,
• a movable unit,
• an elastic support portion connected between the base and the movable unit, and
• an optical function unit disposed on the movable unit,
• wherein the base, the movable unit, and the elastic support portion are constituted by a semiconductor substrate including a first semiconductor layer, a second semiconductor layer, and an insulating layer disposed between the first semiconductor layer and the second semiconductor layer,
• the base is constituted by the first semiconductor layer, the second semiconductor layer, and the insulating layer,
• at least one of the movable unit and the elastic support portion includes a rib portion constituted at least by the first semiconductor layer and disposed on the second semiconductor layer, and
• the first semiconductor layer constituting the rib portion is thinner than the first semiconductor layer constituting the base,
• the method comprising:
• a first step of preparing the semiconductor substrate that includes a portion corresponding to the base, the movable unit, and the elastic support portion;
• a second step of forming a first resist layer in a region corresponding to the base on a surface of the first semiconductor layer which is opposite to the insulating layer after the first step;
• a third step of forming a depression in the first semiconductor layer by etching the first semiconductor layer up to an intermediate portion in a thickness direction using the first resist layer as a mask after the second step;
• a fourth step of forming a second resist layer in a region corresponding to the rib portion on a bottom surface of the depression, a side surface of the depression, and the surface of the first semiconductor layer which is opposite to the insulating layer after the third step;
• and
• a fifth step of forming the rib portion by etching the first semiconductor layer until reaching the insulating layer using the second resist layer as a mask after the fourth step.