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US 7,087,527 B2Granted
Extended kalman filter incorporating offline metrology
AssigneeMicron Technology, Inc.
InventorJim Hofmann
Life of this patent
Estimating the term…
Abstract
An algorithm uses offline metrology to control a process by passing information from an outer control loop to an inner control loop, extended Kalman filter estimator. The inner control loop operates online, and the outer control loop operates asynchronously with respect to the inner control loop. The online control loop is updated for each subsequent process. The offline metrology is optionally updated for each subsequent process.
Claims13
A method comprising:
- in an outer control loop, sending an information statement in the form of process parameter data from an nth process run, where n is an integer greater than zero, to achieve a process parameter first refinement;
- in an inner control loop that uses an extended Kalman filter (EKF), applying the process parameter first refinement to the EKF to achieve a process parameter subsequent refinement;
- sending a control statement in the form of the process parameter subsequent refinement to an (n+m)th process run, Wherein m is greater than or equal to 1;
- and
- applying the refined process parameter to control a physical process.
2 more elements
A method of polishing a substrate comprising:
- in an outer control loop, applying process parameter data from a process model from at least an nth process run, where n is an integer greater than zero, to achieve a process parameter first refinement;
- in an inner control loop that uses an extended Kalman filter (EKF), applying the process parameter first refinement to achieve a process parameter subsequent refinement;
- applying the process parameter subsequent refinement to an (n+m)th process run, wherein m is greater than or equal to 1;
- and
- applying the refined process parameter to control a physical process of polishing the substrate.
2 more elements
A method of planarizing a substrate comprising:
- in an inner loop:
- estimating state variables of a substrate planarizing cycle, wherein estimating includes the use of an extended Kalman filter (EKF) engine;
- estimating the endpoint of the substrate planarizing cycle based upon the estimates of the state variables;
- and
- applying a control statement to a physical process of planarizing the substrate;
- in an outer loop:
- asynchronously comparing at least one of a state variable and an endpoint to an offline metrology database;
- and
- sending an information statement from the outer loop to the inner loop,
- wherein estimating state variables includes:
- calculating total reflectance of a substrate that includes an array region and a periphery region;
- calculating an instantaneous change in reflectance of the substrate relative to the depth being planarized;
- measuring actual reflectance;
- updating the state variables by an EKF estimate;
- and
- estimating whether the reflectance is within a given variance of measured reflectance.
13 more elements
Dependencies are inferred from the claim text.