| 摘要 |
Methods and systems for creating an image-based measurement model based only on measured, image-based training data are presented. The trained, image-based measurement model is then used to calculate values of one or more parameters of interest directly from measured image data collected from other wafers. The image-based measurement models receive image data directly as input and provide values of parameters of interest as output. In some embodiments, the image-based measurement model enables the direct measurement of overlay error. In some embodiments, overlay error is determined from images of on-device structures. In some other embodiments, overlay error is determined from images of specialized target structures. In some embodiments, image data from multiple targets, image data collected by multiple metrologies, or both, is used for model building, training, and measurement. In some embodiments, an optimization algorithm automates the image-based measurement model building and training process. |
