| abstract |
A high data-rate spot-grid array imaging system is provided that compensates for stage vibrations and overcomes the severe linearity requirements of prior art systems. Embodiments include an imaging system with a two-dimensional and periodic array of lenses, each lens imaging a spot in an object plane, such as a semiconductor substrate to be inspected, upon an image plane to image a two-dimensional and periodic array of spots. A sensor is provided in a conjugate image plane with a two-dimensional and periodic array of readout elements, each collecting the signal from one of the spots. A mechanical system moves the substrate in a direction which is nearly parallel to an axis of the array of spots such that as the substrate is moved across the spot array in the scan direction (the y-direction) the spots trace a path which leaves no gaps in the mechanical cross-scan direction (the x-direction). A compensator, such as a servo or a movable mirror, compensates for mechanical inaccuracies in the moving stage, thereby increasing imaging accuracy. In other embodiments, the motion of the mechanical system provides a small overlap between coverage areas of lenses of the lens array in consecutive columns, thereby overcoming the severe linearity requirements of prior art systems and allowing the utilization of cost effective microlens arrays. |