Patent Number: 
Section: claims

1. A wafer defect inspection method, comprising the steps of:radiating an electron beam on a certain area of a wafer;reflecting radiated electrons by applying a negative voltage to said wafer just before said radiated electrons reach a surface of said wafer;forming an image of the reflected electrons;moving said wafer at a certain speed with respect to said radiated electron beam;obtaining a digital image with a time delay integration data acquisition synchronously with a moving speed of said wafer; andextracting a defect of said wafer using an obtained image and displaying a position and an image of said defect,wherein said method further includes a step of displaying on an operation screen a relationship among the values of S, D, L, and P when L is defined as a length in a direction perpendicular to a moving direction of said wafer of which image is being obtained in a range of an inspection object image in the region on which said electron beam is radiated, S is defined as an area of said wafer to be inspected per unit time, D is defined as a size on said wafer, corresponding to a unit pixel of said obtained digital image, and P is defined as an image signal acquisition frequency in said time delay integration formula, as well as a step of adjusting an electron optical system and a wafer moving speed on the basis of user determined S, D, L, and P values,wherein a graph for S=D×L×P is displayed with respect to a plurality of L values and P values respectively by assuming the horizontal axis as D and the vertical axis as S, andwherein said horizontal axis of said graph is displayed as a defect sensitivity obtained by multiplying said D value by a constant less than 1. 2. The method according to claim 1, wherein the L value is 200 μm or under. 3. The method according to claim 1, wherein the D value is 250 nm or under. 4. The method according to claim 1, wherein a condition for operating an electron lens is determined to realize user determined values of D and L with reference to a numerical table that holds said condition for operating said electron lens corresponding to each of said D and L values beforehand. 5. The method according to claim 1, wherein said constant is ⅓ or under. 6. The method according to claim 1, wherein an Si wafer marked with an uneven pattern is used when said user selects said constant, thereby measuring beforehand a potential of said Si wafer and a focal point of an objective lens, as well as a ratio between the size of said marked pattern and the size of a mirror electron image so that said measurement results are set in said numerical table, then a wafer surface potential with respect to said constant is related to an objective lens focal condition according to said results in said numerical table. 7. A defect inspection apparatus, comprising:means for radiating an electron beam on a certain area of a wafer;means for reflecting radiated electrons by applying a negative voltage to said wafer just before said electrons reach a surface of said wafer;means for forming an image of the reflected electrons;means for moving said wafer at a certain speed with respect to said radiated electron beam;means for obtaining a digital image with a time delay integration formula synchronously with a moving speed of said wafer; andmeans for extracting a defect of said wafer using an obtained image and displaying a position and an image of said defect,wherein said method further includes means for displaying a relationship among values of S, D, L, and P when L is defined as a length in a direction perpendicular to a moving direction of said wafer of which image is being obtained in a range of an inspection image in the region on which said electron beam is radiated, S is defined as an area of said wafer to be inspected per unit time, D is defined as a size on said wafer, corresponding to a unit pixel of said obtained digital image, and P is defined as an image signal acquisition frequency in said time delay integration formula, as well as means for adjusting an electron optical system and a wafer moving speed on the basis of user determined values of S, D, L, and P,wherein said apparatus further includes means for displaying an graph for S=D×L×P with respect to a plurality of values of L and P respectively by assuming the horizontal axis as D and the vertical axis as S, andwherein said apparatus further includes means for displaying the horizontal axis of said graph as a defect sensitivity obtained by multiplying a D value by a constant less than 1. 8. The apparatus according to claim 7, wherein the L value is selected within 200 microns or under. 9. The method according to claim 7, wherein the D value is displayed as 250 nm or under. 10. The apparatus according to claim 7, wherein said apparatus further includes means for holding a numerical table in which a condition for operating an electron lens corresponding to each of D and L values is set beforehand and means for determining a condition for operating said electron lens to realize user determined values of D and L with reference to said numerical table.