Patent ID: 6331709
Filing Date: 2001-12-18
Classification: G03F,H01J

Abstract:
A method for detecting an alignment mark on a substrate using an electron beam, comprising the steps of:changing an accelerating voltage of the electron beam in accordance with at least one of thickness and material type of a layer structure of the substrate, and thickness and material type of the alignment mark on the substrate;irradiating the substrate with the electron beam accelerated to each said changed accelerating voltage;detecting at least one of fluorescent X-rays, secondary electrons and backscattered electrons from the substrate irradiated with the electron beam and generating a corresponding detection result;selecting the detection result from the substrate irradiated with the electron beam accelerated to an optimal accelerating voltage for at least one of the layer structure of the substrate and the alignment mark on the substrate; anddetermining a position of the alignment mark based on said selected detection result,wherein the layer structure of the substrate changes each time a cycle of a wafer forming process is repeated and the accelerating voltage is changed in accordance with the change of the layer structure.