BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a flow chart of calibration according to Embodiment 1 of the present invention. FIG. 1B is a flow chart of measurement according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing the principle of a conventional CD-SEM.
FIG. 3 is a diagram explaining the threshold method which is an automatic dimensional measurement method using a signal waveform.
FIG. 4 is a diagram showing a process of general automatic dimensional measurement.
FIG. 5 is a diagram showing the relationship between the position on the viewing field and the beam tilt angle.
FIG. 6A is a schematic diagram showing the relationship between the electron beam landing angle φ and the CD value when φ=0; FIG. 6B shows the case where φ is smaller than the tilt angle θ of the side wall of the pattern; and FIG. 6C shows the case where φ is larger than θ.
FIG. 7A is a diagram showing a concave pyramid as an example polyhedral structure on a calibration sample. FIG. 7B is a diagram showing a convex pyramid as an example polyhedral structure on a calibration sample.
FIG. 8A is a diagram showing a low-power SEM image including a plurality of pyramids. FIG. 8B is a table showing the position of each pyramid on the SEM image, which is converted to the number of pixels and nm length scale.
FIG. 9A is a diagram showing a high-power SEM image of the pyramid when the electron beam landing angle is perpendicular to the pyramid. FIG. 9B is a diagram showing a high-power SEM image of the pyramid when the electron beam landing angle is tilted with respect to the pyramid.
FIG. 10 is a schematic block diagram of an electron microscope.
FIG. 11A is a flow chart of calibration concerning Modification 1 of the present invention. FIG. 11B is a flow chart of measurement concerning Modification 1 of the present invention.
FIG. 12A is a flow chart of calibration concerning Modification 2 of the present invention. FIG. 12B is a flow chart of measurement concerning Modification 2 of the present invention.
FIG. 13 is a diagram showing a flow of a calibration wafer between apparatuses when decreasing the difference in the electron beam landing angle between apparatuses.
FIG. 14A is a diagram showing a pyramidal shape formed on the calibration wafer with the central axis of the pyramid formed perpendicularly to the wafer surface. FIG. 14B is a diagram showing a pyramidal shape with the central axis of the pyramid tilted with respect to the wafer surface.
FIG. 15A is a perspective diagram of a pyramidal structure with a flat top (quadrangular pyramid with a trapezoidal shape) formed on a calibrat5ion wafer. FIG. 15B is a two-dimensional diagram of a pyramidal structure with a flat top (quadrangular pyramid with a trapezoidal shape) with a virtual apex Q′0 obtained.
FIG. 16 is a diagram showing an example of preferable arrangement of pyramids on a calibration sample.
FIG. 17A is a two-dimensional diagram of a sample stage, showing a condition where a fragment for beam landing angle correction is attached to the holder on the sample stage as a calibration sample. FIG. 17B is a flow chart showing a process of adjustment of an optical system.
FIG. 18A is diagram showing example GUIs for setting conditions for automatically performing calibration of the beam landing angle. FIG. 18B is a diagram showing buttons for selecting to perform only measurement of the beam landing angle is to be performed or perform updating of calibration data in addition to the measurement, which are displayed on the GUI screen for setting conditions in FIG. 18A.
FIGS. 19A and 19B are diagrams showing example GUI screens for checking the results of calibration of the beam landing angle.
Patent Application
20070164219
