Method for manufacturing semiconductor dynamic quantity sensor

A method for manufacturing a semiconductor dynamic quantity sensor, comprising steps of:

• preparing a semiconductor substrate including a first semiconductor region and a second semiconductor region isolated from the first semiconductor region by an insulation film interposed therebetween;
• and
• forming a movable portion in the first semiconductor region by etching both the first semiconductor region and the second semiconductor region,
• wherein the movable portion is defined finally at a movable portion defining step that is carried out in a vapor phase atmosphere in the step of forming the movable portion,
• wherein the step of forming the movable portion includes steps of;
• forming a trench in the first semiconductor region;
• etching the second semiconductor region to expose at least a portion of the insulation film corresponding to the trench;
• and
• performing the movable portion defining step in the vapor phase atmosphere,
• wherein the portion of the insulation film is removed at the movable portion defining step so that the movable portion and a fixed portion fixed to the substrate and facing the movable portion are defined.