Detection of environmental conditions in a semiconductor chip

A method, comprising:

• applying a first periodic signal to a first node of a circuit and a second periodic signal to a second node of the circuit, wherein the first and second periodic signals are out of phase with each other by 180 degrees, and wherein a capacitor is coupled to the circuit;
• while the first and second periodic signals are being applied, applying a first DC voltage across third and fourth nodes of the circuit and a second DC voltage across fifth and sixth nodes of the circuit;
• measuring currents through the third, fourth, fifth, and sixth nodes while the first and second DC voltages are being applied;
• and
• determining, based on the measured currents, a value proportional to a capacitance of the capacitor.

A semiconductor chip comprising:

• a substrate;
• a plurality of layers of material disposed on the substrate;
• an active area of the semiconductor chip within which a plurality of circuit elements are disposed in at least some of the layers;
• and
• a capacitor disposed in a keep-out area of the semiconductor chip and electrically coupled to at least one of the circuit elements.

A semiconductor chip comprising:

• a substrate;
• a plurality of layers of material disposed on the substrate;
• an active area of the semiconductor chip within which a plurality of circuit elements are disposed in at least some of the layers;
• a first seal ring disposed in at least some of the layers and surrounding the active area;
• and
• a capacitor disposed between an outer side of the seal ring and an edge of the semiconductor chip, wherein the capacitor is electrically coupled to at least one of the circuit elements.

A semiconductor chip comprising:

• a substrate;
• a plurality of layers of material disposed on the substrate;
• a capacitor disposed in one or more of the layers and having a capacitance of less than 50 atto-Farads (aF);
• a circuit electrically coupled to the capacitor and configured to determine a value based on a capacitance of the capacitor to an accuracy of 5 aF or less, and to generate a signal based on the determined value.