Patent attributes
In one embodiment, wafers are processed to build test structures in the wafers. The wafers may be processed in tools of process steps belonging to a process module. The test structures may be tested to obtain defectivity data. Tool process parameters may be monitored and collected as process tool data. Other information about the wafers, such as metrology data and product layout attribute, may also be collected. A model describing the relationship between the defectivity data and process tool data may be created and thereafter used to relate the process tool data to a yield of the process module. The model may initially be an initial model using process tool data from a limited number of test wafers that contain test structures. The model may also be an expanded model using process tool data from product wafers containing embedded test structures in areas with no product devices.