Patent ID: 8180471

Claim:
A method for estimating a state of a process implemented by a tool for fabricating workpieces, comprising: collecting metrology data associated with a subset of workpieces processed in the tool, the collecting exhibiting an irregular pattern; receiving metrology data associated with a selected state observation for a selected run of the process; determining a tuning factor for the selected run based on the irregular pattern, wherein determining the tuning factor comprises determining the tuning factor for the selected run as a function of a baseline tuning factor of the process and a tuning factor associated with a previous run of the process; discounting the selected state observation based on the determined tuning factor; generating a state estimate of the process based on the discounted selected state observation; controlling at least one process tool operable to implement the process based on the state estimate; and updating the tuning factor for a subsequent run of the process using the equation: λ t + 1 * = λ 2 + λ t * ⁡ ( 1 - λ ) λ 2 + ( 1 + λ t * ) ⁢ ( 1 - λ ) , where λ t+1 * is the updated tuning factor for the subsequent run, λ t * is the tuning factor at the selected run, and λ is the baseline tuning factor of the process.