Scanning electron microscope and CD measurement calibration standard specimen
A calibration standard specimen is provided to have formed therein calibrating patterns of a lattice shape discontinuously arrayed, and particular alignment patterns respectively disposed near the calibrating patterns so that the positioning of the specimen can be made to match the calibrating patterns to the measurement points.
1. A scanning electron microscope that irradiates an electron beam onto a sample to scan it, detects secondary electrons generated from said sample due to said irradiation of said electron beam, and measures dimensions of a fine pattern formed on said sample according to an image resulting from said detection of said secondary electrons,
wherein said microscope has a calibration standard specimen provided to have formed therein a plurality of calibrating patterns discontinuously arrayed and alignment patterns respectively disposed for positioning said specimen to match said calibrating patterns to measurement points.
2. A scanning electron microscope according to claim 1 , wherein said plurality of calibrating patterns have a plurality of line-and-space patterns discontinuously arrayed in a first direction and a plurality of line-and-space patterns discontinuously arrayed in a second direction perpendicular to said first direction.
3. A scanning electron microscope according to claim 1 , wherein said alignment patterns are respectively disposed near said plurality of calibrating patterns.
4. A scanning electron microscope according to claim 3 , wherein said alignment patterns are formed of patterns of at least four kinds different in their shapes, and arrayed such that the alignment patterns of the same shape are not adjacent to each other.
5. A scanning electron microscope according to claim 1 , said microscope comprising:
means for inputting a population variance of said dimensions of said calibrating patterns of said calibration standard specimen or information to acquire said population variance, and a necessary calibration accuracy; and
means for calculating and setting the number of necessary measurement points on the basis of said population variance of said dimensions of said calibrating patterns and said necessary calibration accuracy.
6. A scanning electron microscope according to claim 1 , wherein said calibrating patterns are formed on a semiconductor wafer.
7. A calibration standard specimen for a scanning electron microscope,
said calibration standard specimen having a plurality of calibrating patterns discontinuously arrayed, and alignment patterns respectively provided for positioning said specimen to match said calibrating patterns to measurement points,
wherein said plurality of calibrating patterns are formed of a plurality of line-and-space patterns discontinuously arrayed in a first direction, and a plurality of line-and-space patterns discontinuously arrayed in a second direction perpendicular to said first direction.
8. A calibration standard specimen according to claim 7 , wherein said alignment patterns are formed of patterns of at least four kinds different in their shapes and respectively arrayed in combination with and disposed near said plurality of calibrating patterns such that said alignment patterns of the same shape are not adjacent to each other.
9. A calibration standard specimen according to claim 7 , wherein said specimen is formed on a semiconductor wafer.