Sample dimension inspecting/measuring method and sample dimension inspecting/measuring apparatus
View Patent ↗One of principal objects of the present invention is to provide a sample dimension measuring method for detecting the position of an edge of a two-dimensional pattern constantly with the same accuracy irrespective of the direction of the edge and a sample dimension measuring apparatus. According to this invention, to accomplish the above object, it is proposed to correct the change of a signal waveform of secondary electrons which depends on the direction of scanning of an electron beam relative to the direction of a pattern edge of an inspection objective pattern. It is proposed that when changing the scanning direction of the electron beam in compliance with the direction of a pattern to be measured, errors in the scanning direction and the scanning position are corrected. In this configuration, a sufficient accuracy of edge detection can be obtained irrespective of the scanning direction of the electron beam.
1. In a method of measuring a pattern by specifying the position of a pattern edge of an inspection objective pattern by using a signal waveform acquired by scanning a charged-particle beam on a sample so as to measure a distance between design data of said inspection objective pattern and said pattern edge,
a pattern inspecting/measuring method comprising: measuring a pattern edge direction of said inspection objective pattern, measuring a relative angle the scanning direction of said charged-particle beam makes to the pattern edge direction of said inspection objective pattern, estimating a distortion of said signal waveform attributable to said relative angle and correcting said estimated distortion of signal waveform, whereby a pattern edge position is specified from said corrected signal waveform.
2. A pattern inspecting/measuring method according to claim 1 comprising: preparing, from image data of said objective pattern acquired by scanning said charged-particle beam in a constant direction, said signal waveform as a line profile, estimating a distortion of said line profile from a relative angle the scanning direction of said charged-particle beam makes to a pattern edge of said inspection objective pattern and correcting a distortion of said estimated line profile, whereby a pattern edge position is specified from said corrected line profile.
3. In a method of measuring a pattern by specifying the position of a pattern edge of an inspection objective pattern by using a signal waveform acquired by scanning a charged-particle beam on a sample so as to measure a distance between design data of said inspection objective pattern and said pattern edge,
a pattern inspecting/measuring method comprising: measuring the direction of a pattern edge of said inspection objective pattern to change the scanning direction of the charged-particle beam in accordance with a measured pattern edge direction.
4. In a method of measuring a pattern by specifying the position of a pattern edge of an inspection objective pattern by using a signal waveform acquired by scanning a charged-particle beam on a sample so as to measure a distance between design data of said inspection objective pattern and said pattern edge,
a pattern inspecting/measuring method comprising changing the scanning direction of said charged-particle beam in accordance with the direction of a change of gradation a gradation image of design data of said inspection objective pattern exhibits at a scanning position.
5. A pattern inspecting/measuring method according to claim 3 or 4 comprising: measuring errors in the scanning position and direction of said charged-particle beam and estimating, from measured errors, errors in the scanning position and direction of said charged-particle beam at an arbitrary position and in an arbitrary direction, whereby the estimated errors in the scanning position and direction are corrected in advance so as to permit said charged-particle beam to scan at a correct position and in a correct direction.
6. An inspecting/measuring method according to claim 3 or 4 , wherein the charged-particle beam is caused to selectively scan only a position of measurement of a pattern edge of said inspection objective pattern.
7. A pattern inspecting/measuring method according to claim 1 , wherein a pattern edge specified from said signal waveform is formed into one figure on the basis of design data of said inspection objective pattern.
8. A pattern inspecting/measuring method according to claim 1 , wherein a plurality of candidates for positions of pattern edges of said inspection objective pattern are selected from said signal waveform and stored and when forming one figure on the basis of design data of said inspection objective pattern, appropriate pattern edge positions are selected from said plurality of pattern edge candidates.
9. A pattern inspecting/measuring method according to claim 1 comprising: matching design data of said inspection objective pattern with a pattern by using the pattern edge position of inspection objective pattern specified from said signal waveform, whereby coordinates of the pattern edge position of inspection objective pattern specified from said signal waveform is corrected in accordance with the result of pattern matching.
10. A pattern inspecting/measuring method according to claim 1 , wherein when specifying the pattern edge position of inspection objective pattern from said signal waveform, information about a change in cubical shape of said inspection objective pattern is measured by changing the condition for specifying.
11. A pattern inspecting/measuring method according to claim 1 , wherein the pattern edges of said inspection objective pattern are classified by using features of shape of said signal waveform.
12. An arithmetic unit for measuring the dimension of a pattern on a sample on the basis of an image obtained under scanning a charged-particle beam emitted from a charged-particle source on said sample, wherein said arithmetic apparatus calculates a direction of a pattern edge formed on said sample and a relative angle the scanning direction of said charged-particle beam makes to the edge direction of the pattern, a signal waveform detected from said pattern edge is corrected on the basis of a distortion corresponding to the calculated relative angle and the dimension of said pattern is measured on the basis of the corrected signal waveform.
13. An arithmetic unit according to claim 12 , wherein said arithmetic apparatus measures a dimension between design data of said pattern and a pattern edge on said image.