Algorithm for real-time process control of electro-polishing
AssigneeApplied Materials, Inc.
InventorsAntoine P. Manens, Alain Duboust, Siew S. Neo, Liang-Yuh Chen
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Abstract
Method and apparatus for process control of electro-processes. The method includes electro-processing a wafer by the application of two or more biases and determining an amount of charge removed as a result of each bias, separately. In one embodiment, an endpoint is determined for each bias when the amount of charge removed for a bias substantially equals a respective target charge calculated for the bias.
Claims14
A method of determining removal of material from a plurality of points on a wafer, the removal being effected at least in part by electro-chemical activity, the method comprising:
- determining trajectories for a plurality of points on a wafer relative to a plurality of electrodes each capable of being separately biased at different bias levels during electro-chemical processing;
- based on the trajectories, determining an amount of time each of the plurality of points spends being affected by each of the electrodes;
- based on the trajectories and a predetermined charge-removal relationship relating charge removed to amount of material removed from the wafer, determining an average amount of material removed from the wafer as effected by each of the electrodes;
- and
- for each point of the plurality of points on the wafer, calculating an amount of material removed at the point as the sum of the average amounts of material removed from the wafer as effected by each of the electrodes weighted by the corresponding amount of time spent being affected by the respective electrode.
A method of electro-processing a wafer, comprising:
- providing an electrode assembly comprising at least two separately biased electrodes;
- providing a process model which relates a charge for each of the electrodes to an amount of material removed at each of a plurality of points on a wafer on the basis of a predetermined trajectory of the plurality of points relative to the electrodes and a predetermined charge-removal relationship which relates charge removed to amount of material removed from the wafer;
- for a specified desired profile of the wafer, determining a target charge for each electrode according to the process model;
- moving the wafer relative to the electrodes according to the predetermined trajectory of the plurality of points;
- and
- terminating each bias to the respective electrode upon reaching the respective target charge.
Dependencies are inferred from the claim text.