US Patent 7184134 Real-time monitoring apparatus for plasma process

A real-time monitoring apparatus for a plasma process comprises a plurality of measuring units (10) mounted on a semiconductor wafer, a receiving device (7) for receiving a signal transmitted from each of the measuring units (10), and a data processing apparatus (6) for detecting a condition of the semiconductor wafer (3) based on the received signal. In this apparatus, each of the measuring units (10) includes at least one plasma process detection sensor (11), a light-emitting device (16) for converting an output of the plasma process detection sensor into an optical output, and a power supply (17) for supplying drive power to the light-emitting device (16).