Determination of gain for eddy current sensor

• Main Authors: SWEDEK BOGUSLAW A, BENNETT DOYLE E, IRAVANI HASSAN G, LIU TZU-YU, TU WENIANG, SHEN SHIH-HAUR, XU KUN, CARLSSON INGEMAR
• Format: Patent
• Language: English
• Published: 01.03.2016
• Subjects: BASIC ELECTRIC ELEMENTS; DRESSING OR CONDITIONING OF ABRADING SURFACES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS; GRINDING; MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; PERFORMING OPERATIONS; POLISHING; SEMICONDUCTOR DEVICES; TRANSPORTING

In one aspect, a method of controlling polishing includes receiving a measurement of an initial thickness of a conductive film on a first substrate prior to polishing the first substrate from an in-line or stand-alone monitoring system, polishing one or more substrates in a polishing system, the one or more substrates including the first substrate, during polishing of the one or more substrates, monitoring the one or more substrates with an eddy current monitoring system to generate a first signal, determining a starting value of the first signal for a start of polishing of the first substrate, determining a gain based on the starting value and the measurement of the initial thickness, for at least a portion of the first signal collected during polishing of at least one substrate of the one or more substrates, and calculating a second signal based on the first signal and the gain.