Filtering During In-Situ Monitoring of Polishing
AssigneeApplied Materials, Inc.
InventorSivakumar Dhandapani
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Abstract
A method of controlling polishing includes polishing a substrate, monitoring the substrate during polishing with an in-situ monitoring system, filtering a signal from the monitoring system to generate a filtered signal, and determining at least one of a polishing endpoint or an adjustment for a polishing rate from the filtered signal. The filtering includes modelling a plurality of periodic disturbances at a plurality of different frequencies using a plurality of disturbance states, modelling an underlying signal using a plant state, and applying a linear prediction filter to the plant state and the plurality of disturbance states to generate a filtered signal representing the underlying signal.
Claims20
A method of controlling polishing, comprising:
- polishing a substrate;
- during polishing monitoring the substrate with an in-situ monitoring system, the monitoring including generating a signal from a sensor, the signal including a sequence of measured values;
- filtering the signal to generate a filtered signal, the filtered signal including a sequence of adjusted values, the filtering including
- modelling a plurality of periodic disturbances, using a plurality of disturbance states, at a plurality of different frequencies,
- modelling an underlying signal, using a plant state, and
- applying a linear prediction filter to the plant state and the plurality of disturbance states to generate a filtered signal representing the underlying signal;
- and
- determining at least one of a polishing endpoint or an adjustment for a polishing rate from the filtered signal.
A computer program product, comprising a computer-readable medium having instructions, which, when executed by a processor, cause the processor to:
- receive, during polishing of a substrate, a signal from an in-situ monitoring system, the signal including a sequence of measured values;
- filter the signal to generate a filtered signal, the filtered signal including a sequence of adjusted values, wherein the instructions to filter the signal include instructions to
- model a plurality of periodic disturbances, using a plurality of disturbance states, at a plurality of different frequencies,
- model an underlying signal, using a plant state, and
- apply a linear prediction filter to the plant state and the plurality of disturbance states to generate a filtered signal representing the underlying signal;
- and
- determine at least one of a polishing endpoint or an adjustment for a polishing rate from the filtered signal.
A polishing system, comprising:
- a platen to support a polishing pad;
- a carrier head to hold a substrate in contact with the polishing pad during polishing;
- an in-situ monitoring system configured to generate a signal from a sensor that monitors the substrate during polishing, the signal including a sequence of measured values;
- and
- a controller configured to
- receive, during polishing of the substrate, the signal from the in-situ monitoring system,
- filter the signal to generate a filtered signal, the filtered signal including a sequence of adjusted values, wherein the controller is configured to filter the signal by
- modeling a plurality of periodic disturbances, using a plurality of disturbance states, at a plurality of different frequencies,
- modeling an underlying signal, using a plant state, and
- applying a linear prediction filter to the plant state and the plurality of disturbance states to generate a filtered signal representing the underlying signal, and
- determine at least one of a polishing endpoint or an adjustment for a polishing rate from the filtered signal.
Dependencies are inferred from the claim text.