Patent ID: 7685877

Claim:
A semiconductor mechanical quantity sensor comprising: a first layer formed by a silicon substrate; a second layer formed by an insulation layer disposed on said first layer; a third layer formed by a silicon layer disposed on said second layer; a fourth layer formed by an insulation layer disposed on said third layer; and a fifth layer formed by a silicon layer disposed on said fourth layer; wherein the thickness of the fifth layer is greater than the thickness of the third layer, said fifth layer is provided with a weight being movable due to the effect of the mechanical quantity, a movable electrode being included in said weight, a fixed electrode facing said movable electrode, and an electric routing path being separated from said weight and extending in a direction perpendicular to said first layer; said third layer is formed by a polysilicon layer containing high density impurities and extending in a direction parallel with said first layer, said polysilicon layer and said electric routing path are electrically connected via a bottom contact for an electric connection, the bottom contact being formed below the electric routing path and between said third layer and said fifth layer.