METROLOGY TARGET DESIGN FOR TILTED DEVICE DESIGNS

摘要

Metrology methods, modules and targets are provided, for measuring tilted device designs. The methods analyze and optimize target design with respect to the relation of the Zernike sensitivity of pattern placement errors (PPEs) between target candidates and device designs. Monte Carlo methods may be applied to enhance the robustness of the selected target candidates to variation in lens aberration and/or in device designs. Moreover, considerations are provided for modifying target parameters judiciously with respect to the Zernike sensitivities to improve metrology measurement quality and reduce inaccuracies.

主权项

1. A method of metrology target design, the method comprising calculating a Zernike sensitivity of pattern placement errors (PPEs) of at least one device design and of a plurality of metrology target designs, and selecting a best metrology target design according to a value of a cost function derived from the calculated Zernike sensitivities, the cost function quantifying a similarity of the Zernike sensitivity between the at least one device design and the plurality of metrology target designs, wherein at least one of the calculating and the selecting is carried out by at least one computer processor.