Method and apparatus for measuring displacement between patterns and scanning electron microscope installing unit for measuring displacement between patterns

A method for measuring a displacement, the method comprising the steps of:

• entering height information of patterns formed on a sample, into a computer;
• recording data that represents correspondence between control values of a converging lens, objective lens, and deflector of a scanning electron microscope observing the sample, the control values being used to control a direction of an electron beam incident upon the sample, and a deviation in an angle of incidence of the electron beam upon the sample with respect to a direction perpendicular to the sample;
• storing into the computer the respective control values of the converging lens, objective lens, and deflector operative when the sample is being observed through the scanning electron microscope;
• acquiring an image of the sample while observing the sample through the scanning electron microscope;
• and
• calculating the displacement between the patterns formed on the sample in different pattern-forming steps, wherein the calculation is based on a combination of a displacement amount calculated from a correspondence data recorded in the recording step, the computer-stored control values of the converging lens, objective lens, and deflector of the scanning electron microscope being used for the observation, and the pattern height value entered into the computer and a displacement amount between the plurality of patterns calculated from the pattern image acquired in the step of acquiring the image of the pattern.

A scanning electron microscope system equipped with a displacement measuring apparatus, comprising:

• a scanning electron microscope equipped with an electron beam source, a converging lens, a deflector, an objective lens, a sample stage, and a secondary-electron detector;
• a control unit for controlling the electron beam source, the converging lens, the deflector, the objective lens, the sample stage, and the secondary-electron detector of the scanning electron microscope;
• a data recorder for recording data that represents correspondence between respective control values of the converging lens, objective lens, and deflector operative when the scanning electron microscope is scanning an electron beam, and an angle of incidence of the electron beam upon a sample during the scan;
• and
• a computer including an entry unit for entering height information of patterns, and a storage region for temporary storage of image data obtained during imaging with the scanning electron microscope;
• wherein the computer calculates the displacement between the patterns formed in different pattern-forming steps based on a combination of a displacement amount between the plurality of patterns calculated from all of the image data obtained during imaging with the scanning electron microscope and a displacement amount calculated from the pattern height information entered from the entry unit and the correspondence data recorded in the data recorder.