Patent ID: 7015715

Claim:
A hybrid semiconductor comprising: a first substrate comprising: a metal layer; an insulating layer adjacent to the metal layer; and a contact adjacent to the insulating layer; a second substrate coupled to the first substrate; and a circuit, coupled to the metal layer and to the contact of the first substrate, adapted to measure a distance between the first substrate and the second substrate, wherein the distance measured by the circuit is based on a capacitance between the contact and the second substrate, with the capacitance based on an area of the contact and the distance between the first substrate and the second substrate, and wherein the circuit comprises; a buffer having a first and second input terminal and an output terminal that provides the output signal, wherein the output terminal is coupled to the second input terminal and to the metal layer of the first substrate, and the first input terminal is coupled to the contact; a switch coupled to the first input terminal to selectively assert a first reference signal to the first input terminal; and a capacitor coupled to the first input terminal, the capacitor adapted to receive a second reference voltage after the switch opens to deassert the first reference signal.