Patent ID: 7690255

Claim:
A process of fabricating a three-axis inertial sensor comprising a z-axis sensing device, an x-axis sensing device, and a y-axis sensing device, the process comprising: providing a silicon-on-oxide (SOI) wafer comprising a first conductive layer separated from a second conductive layer by an insulative buried oxide (BOX) layer; fabricating the SOI wafer to partially define in the first conductive layer thereof at least a portion of a proof mass for the z-axis sensing device, at least a portion of a proof mass for the x-axis sensing device, and at least a portion of a proof mass for the y-axis sensing device; depositing a conductive deposited layer on the SOI wafer and over the first conductive layer; patterning the deposited layer to define at least one suspension spring for the proof mass of the z-axis sensing device; bonding the SOI wafer to a substrate so that the first conductive layer of the SOI wafer faces the substrate; etching the second conductive layer of the SOI wafer to form a fixed electrode of the z-axis sensing device; and then etching portions of the BOX layer to fully release the proof masses and define a capacitive gap between the fixed electrode and the proof mass of the z-axis sensing device.