DEVICE METROLOGY TARGETS AND METHODS

摘要

Metrology methods and targets are provided, that expand metrological procedures beyond current technologies into multi-layered targets, quasi-periodic targets and device-like targets, without having to introduce offsets along the critical direction of the device design. Several models are disclosed for deriving metrology data such as overlays from multi-layered target and corresponding configurations of targets are provided to enable such measurements. Quasi-periodic targets which are based on device patterns are shown to improve the similarity between target and device designs, and the filling of the surroundings of targets and target elements with patterns which are based on device patterns improve process compatibility. Offsets are introduced only in non-critical direction and/or sensitivity is calibrated to enable, together with the solutions for multi-layer measurements and quasi-periodic target measurements, direct device optical metrology measurements.

主权项

1. A method of directly measuring metrology parameters on devices, the method comprising:
measuring at least one metrology parameter from at least one portion of a device design selected to have a plurality of irregularly repeating units comprising specified features, along at least one direction of the at least one portion, and calibrating sensitivity using at least one of: an intensity of diffraction orders orthogonal to the at least one direction; introduced offsets along a non-critical direction; target cells with introduced offsets adjacent to the device portion(s); and at least one sensitivity calibration target, wherein the measuring is carried out scatterometrically on a plurality of targets to provide layer-specific metrology parameters, at least one of the targets being part of the at least one device portion having N>2 overlapping layers, wherein the plurality of targets comprises at least one of: N cell pairs, each pair having opposite offsets at a different layer; N cells with selected intended offsets; N or fewer cells with selected intended offsets configured to utilize pupil information; and N-cell calibration targets alongside between N−1 and two overlay targets.