Patent ID: 7630068

Claim:
A method for mask blank defect inspection comprising: a first step including: radiation on a first mask blank having formed thereon a dot pattern serving as a reference with extreme ultraviolet light; and obtainment of a first focus position where a signal intensity of a first darkfield detection image produced by the scatter-reflected light is maximum; a second step including: radiation at the first focus position on a second mask blank, which is an inspection target with extreme ultraviolet light; scanning on the second mask blank in a direction perpendicular to an optical axis of the scatter-reflected light; and detection of a signal intensity of a second darkfield detection image produced by the scatter-reflected light; a third step including detection of a defect in the second mask blank based on the signal intensity of the second darkfield detection image; a fourth step including: radiation on a surface of a glass substrate, which is a base of the second mask blank with any one or all of visible light, ultraviolet light, and far-ultraviolet light; detection of a defect on the glass substrate by using reflected light; and extraction of a glass substrate which has a value of defects equal to or smaller than a specified value; a fifth step including: formation of the second mask blank by making a multilayer adhere to the glass substrate which has a value of defects equal to or smaller than the specified value a sixth step including: radiation on a fourth mask blank having formed thereon a line pattern serving as a reference with extreme ultraviolet light; and obtainment of a third focus position where a signal intensity of a fifth darkfield detection image produced by the scatter-reflected light is maximum; a seventh step including: radiation at the third focus position on the second mask blank, which is an inspection target with extreme ultraviolet light; scanning on the second mask blank in a direction perpendicular to an optical axis of the scatter-reflected light; and detection of a signal intensity of a sixth darkfield detection image produced by the scatter-reflected light; an eighth step including detection of a defect position in the second mask blank based on the signal intensity of the sixth darkfield detection image; a ninth step including: radiation on the second mask blank with extreme ultraviolet light while changing the focus position at the defect position; and detection of a signal intensity of a seventh darkfield detection image produced by the scatter-reflected light; a tenth step of obtaining a fourth focus position where a signal intensity of the seventh darkfield detection image is maximum; an eleventh step of determining a type of the defect in the second mask blank based on the third and fourth focus positions; and a twelfth step of outputting to a user a determination of the type of defect that is detected.