Tracking and/or predicting the yield of a semiconductor process. In an embodiment, a tracking method monitors the yield at each layer of the process. This can be used to determine how to proceed. In an embodiment, the prediction method measures the values of at least one attribute of each conductive via on a substrate before the lithography process. The measured values are then compared to predefined values for the same attribute, to determine any deviation. Based on this comparison, an overlay yield of the lithography process is predicted.