| 摘要 |
PURPOSE: An apparatus and method for determining an overlay error are provided to reduce overlay errors by reducing the change of a recipe-to-recipe. CONSTITUTION: A model of a first structure is comprised by using the measured scattering properties of a first target(718). The model is modified by overlaying a first model structure with a middle model structure(728). An asymmetrical induction overlay error between the first model structure and a second model structure is determined by using the modified model(734). The model is additionally modified by replacing the middle model structure with the second model structure(740). A second defect-induction overlay error between the first model structure and the second model structure is calculated. An overlay error is determined in a second target by using the second defect-induction overlay error. [Reference numerals] (702) Measuring an L1 target; (718) Reconstructing an L1 model; (728) Modifying the L1 model by defining a zero point and inserting a perfect centered top grid; (734) Calculating ΔOV_L1 for the modified model for each recipe(r); (736) Measuring ΔOV_m for a complete structure; (738) Calculating an L2 asymmetry parameters; (740) Modifying the model by replacing the perfect grid with the calculated structure |
