| 摘要 |
A micro-machined absolute pressure sensor and process for making the same. A semiconductor membrane having a welled portion connected to a planar periphery is formed in recess in a silicon substrate through etching and boron diffusion. A dielectric pad is formed on a portion of the planar periphery, and a bonding layer of polysilicon or amorphous silicon is deposited over the semiconductor membrane and the dielectric pad. After an etching process that defines the outline of the semiconductor membrane, the bonding layer is bonded to a nonconductive substrate in a vacuum using electrostatic bonding or wafer bonding, forming a vacuum-sealed reference cavity. A first and a second conductor are disposed on an upper surface of the nonconductive substrate. The first conductor serves as a capacitor plate disposed within the reference cavity and is connected to a transfer lead that passes from the cavity. The transfer lead is electrically isolated from the semiconductor membrane by the dielectric pad. The second conductor is electrically connected to the semiconductor membrane. The semiconductor membrane and the capacitor plate store an electrical charge that varies as a function of the distance between the capacitor plate and the semiconductor membrane. The semiconductor membrane flexes in response to pressure, changing the capacitance and the charge, so as to indicate the pressure of external fluid acting on the semiconductor membrane. |
