Patent ID: 7326586

Claim:
A method for manufacturing a semiconductor physical quantity sensor, which includes a multi-layered substrate, a cavity, a groove, a movable portion and a fixed portion, wherein the multi-layered substrate includes a support substrate, an embedded insulation film, and a semiconductor layer, which are stacked in this order, wherein the cavity extends in a horizontal direction of the multi-layered substrate and disposed between the semiconductor layer and the embedded insulation film, wherein the groove is disposed in the semiconductor layer and reaches the cavity, wherein the movable portion is disposed in the semiconductor layer and separated from the embedded insulation film by the groove and the cavity so that the movable portion is movable, and wherein the fixed portion is supported on the support substrate and separated by the groove, the method comprising the steps of: preparing the multi-layered substrate having a sacrifice layer, which is embedded in the semiconductor layer so that the sacrifice layer is disposed at a cavity-to-be-formed portion; forming the groove from an upper surface of the semiconductor layer by a trench etching method, wherein the groove extends in a vertical direction of the multi-layered substrate and reaches the sacrifice layer; and selectively etching the sacrifice layer from a bottom of the groove to form the cavity extending in the horizontal direction so that the movable portion is formed.