Method and system to predict lithography focus error using simulated or measured topography

摘要

A method and system to predict lithography focus error using chip topography data is disclosed. The chip topography data may be measured or simulated topography data. A plane is best fitted to the topography data, and residuals are computed. The residuals are then used to make a prediction regarding the focus error. The density ratio of metal to dielectric may also be used as a factor in determining the predicted focus error.

主权项

1. A method for predicting lithography focus error for a chip by analyzing chip topography data, comprising:
a) computing a focal plane that best fits a subset of the chip topography data; b) computing a minimal local residual of the focal plane; c) updating a total focus error value with the minimal local residual; d) acquiring a new subset of chip topography data based on chip density data and geometry data, wherein the chip density data comprises the makeup of substrate materials at the surface within a logical area, and wherein the geometry data comprises the width of metal lines; and repeating steps a), b), c), and d) until each data point within the chip topography data is considered in at least one subset, wherein step d) is not repeated on the last iteration, thereby computing a focus error value for the chip.