Overlay abnormality gating by Z data

摘要

The present disclosure relates to a method of monitoring wafer topography. A position and orientation of a plurality first alignment shapes disposed on a surface of a wafer are measured. Wafer topography as a function of wafer position is modeled by subjecting the wafer to an alignment which simultaneously minimizes misalignment between the wafer and a patterning apparatus and maximizes a focus of radiation on the surface. A non-correctable error is determined as a difference between the modeled wafer topography and a measured wafer topography. A maximum non-correctable error per field is determined for a wafer, and a mean variation in the maximum non-correctable error across each field within each wafer of a lot is determined, both within a layer and across layers. These values are then verified against a set of statistical process control rules to determine if they are within a specification limit of the manufacturing process.

主权项

1. A method of screening a wafer with a plurality of reticle fields, the method comprising:
modeling a topography over a surface of the wafer based on a plurality of first alignment shapes in a first layer overlying the surface to generate a modeled topography for the first layer, wherein the plurality of first alignment shapes is spaced over the surface with a first resolution; measuring the topography with a second resolution greater than the first resolution to generate a measured topography for the first layer; determining a plurality of first non-correctable errors for the first layer as a difference between the modeled topography and the measured topography, wherein the plurality of first non-correctable error are determined at a plurality of locations across the surface of the wafer; determining a maximum first non-correctable error from the plurality of first non-correctable errors for each reticle field of the plurality of reticle fields; and discarding the wafer or re-disposing the first layer if the maximum first non-correctable error within one or more reticle fields is above a first threshold.