Automatic virtual metrology system design and implementation

An automatic virtual metrology (AVM) system that consists of a model-creation server and many AVM servers is proposed. The model-creation server will generate the first set of data quality evaluation models and virtual metrology (VM) conjecture models of a certain equipment type. Under fab-wide VM deployment, the model-creation server can also fan out the first set of models generated to all the AVM servers of the same equipment type. Also, each individual fan-out-accepter’s AVM server can perform an automatic model refreshing process to promptly refresh its own data quality evaluation models and VM conjecture models. As such, the VM accuracy can be maintained and the AVM server is then ready to serve. This paper gives an overview to the AVM system and elaborates the automatic data quality evaluation schemes and the automatic model refreshing schemes.