Test structure for the in-plane locations of project features with nanometer-level accuracy traceable to a coordinate measurement system

A new test structure is reported. It is designed to measure the positions of the images of an array of features projected from a mask into a resist film on substrate with accuracy better than 10 nm. The resist film on the substrate covers a nominally matching array of partially formed versions of the test structure prepatterned in a conducting film. Instances of the finished structure are formed on the substrate by further selective removal of conducting material from the partially formed test structures where they are overlaid by images of the fiducial marks on the mask. At each array point, the feature of the completed test structure that is defined by the overlay of the image of the fiducial marks on the mask is called the pointer. The part of the partially formed test structure that is unaffected by the overlay of the images of the fiducial marks on the mask serves as a ruler. Electrical testing accurately provides the precise location of the pointer relative to the ruler within each test structure. The locations of the rulers prepatterned on the substrate are determined with a coordinate measurement system (CMS) called the NIST (National Institute of Standards and Technology) Molecular Measuring Machine (M-Cubed).<>