Filtering during in-situ monitoring of polishing
AssigneeApplied Materials, Inc.
InventorSivakumar Dhandapani
Life of this patent
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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.
Claims21
A method of controlling polishing, comprising:
- polishing a substrate at a polishing station;
- 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 at a plurality of different frequencies,
- modelling an underlying signal, and
- applying a linear prediction filter to the modelled underlying signal with the modelled plurality of periodic disturbances to generate the filtered signal representing the underlying signal with the periodic disturbances filtered out;
- and
- causing the polishing system to at least one of halt polishing of the substrate or adjust a polishing rate of the substrate based on 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 at a plurality of different frequencies,
- modeling an underlying signal, and
- applying a linear prediction filter to the modelled underlying signal with the modelled plurality of periodic disturbances to generate the filtered signal representing the underlying signal with the periodic disturbances filtered out, and
- at least one of halt polishing or adjust a polishing rate based on the filtered signal.
A non-transitory computer readable medium having instructions for causing one or more computers to:
- receive a signal from a sensor of an in-situ monitoring system that monitors a substrate during polishing of the substrate, 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, the instructions to filter including instructions to
- model a plurality of periodic disturbances at a plurality of different frequencies,
- model an underlying signal, and
- apply a linear prediction filter to the modelled underlying signal with the modelled plurality of periodic disturbances to generate the filtered signal representing the underlying signal with the periodic disturbances filtered out;
- and
- cause the polishing system to at least one of halt polishing of the substrate or adjust a polishing rate of the substrate based on the filtered signal.
Dependencies are inferred from the claim text.