Abstract: A mask is reused to form the same pattern in multiple layers in semiconductor processing. Reference marks that allow alignment accuracy to be checked are also formed with the mask. The manner of using the mask advantageously mitigates interference between reference marks in different layers.

Abstract: Different types of test structures are formed during semiconductor processing. One type of test structure comprises features that are aligned with one another and that are formed from different layers. Other types of test structures comprise features formed from respective layers that are not aligned with other test structure features. The different types of test structures are formed with a single mask that is used in a manner that also allows alignment marks to be formed which do not interfere with one another as subsequent layers are patterned. The different types of test structures can provide insight into performance characteristics of different types of devices as the semiconductor process proceeds.