Determination of gain for eddy current sensor

• Main Authors: Iravani, Hassan G, Xu, Kun, Bennett, Doyle E, Shen, Shih-Haur, Carlsson, Ingemar, Liu, Tzu-Yu, Swedek, Boguslaw A, Tu, Wen-Chiang
• Format: Patent
• Language: English
• Published: 11.02.2020
• 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

A method of controlling polishing includes polishing a substrate at a first polishing station, monitoring the substrate with a first eddy current monitoring system to generate a first signal, determining an ending value of the first signal for an end of polishing of the substrate at the first polishing station, determining a first temperature at the first polishing station, polishing the substrate at a second polishing station, monitoring the substrate with a second eddy current monitoring system to generate a second signal, determining a starting value of the second signal for a start of polishing of the substrate at the second polishing station, determining a gain for the second polishing station based on the ending value, the starting value and the first temperature, and calculating a third signal based on the second signal and the gain.