Charged particle beam apparatus and dimension measuring method
View Patent ↗There is provided a charged particle beam apparatus which allows implementation of a high-reliability and high-accuracy dimension measurement even if height differences exist on the surface of a sample. The charged particle beam apparatus includes the following configuration components: An acquisition unit for acquiring a plurality of SEM images whose focus widths are varied in correspondence with the focal depths, a determination unit for determining, from the plurality of SEM images acquired, a SEM image for which the image sharpness degree of the partial domain including a dimension-measuring domain becomes the maximum value, and a measurement unit for measuring the dimension of the predetermined domain from the SEM image whose image sharpness degree is the maximum value.
1. A dimension measuring method for measuring a pattern formed on a sample in accordance with detection of electrons obtained by scanning the sample with an electron beam, said dimension measuring method comprising steps of:
setting a two-dimenstional partial domain including two edge portions of said pattern within scanning range of said electron beam;
obtaining a plurality of images with different focus conditions by changing focus of said electron beam;
evaluating the plurality of images with different focus conditions in accordance with a sharpness degree of said two-dimensional partial domain; and
measuring dimension between two edges of one of the images with the highest sharpness degree.
2. A dimension measuring method according to claim 1 , wherein image-sharpness-degree evaluation of said two-dimensional partial domain is carried out by using a differential filter.
3. A dimension measuring method according to claim 2 , wherein an application direction of said differential filter is determined in accordance with edge forming direction within said two-dimensional partial domain.
4. A dimension measuring method according to claim 3 , wherein when at least one of said edges in said two-dimensional partial domain is formed with line segment only in a certain direction, a differential filter of a perpendicular direction is applied to said line segment.
5. A dimension measuring method according to claim 3 , wherein when at least one of said edges in said two-dimensional partial domain is formed with line segments in two directions, a differential filter of a perpendicular direction is applied to said two line segments.
6. A dimension measuring method according to claim 1 , wherein two two-dimensional partial domains are set in said scanning region of said electron beam, and dimension between edges formed in said two two-dimensional partial domains is measured.
7. A dimension measuring method according to claim 1 , wherein a plurality of two-dimensional domains are set in said scanning region of said electron beam, and dimension between two edges at each of said plurality of two-dimensional partial domains are measured.
8. A dimension measuring method according to claim 7 , wherein said image-sharpness-degree evaluation is carried out at each of said plurality of two-dimensional partial domains.
9. A pattern dimension measuring apparatus including:
a processing unit for measuring dimension of a pattern formed on a sample in accordance with a detection signal detected by a scanning electron microscope, wherein said processing unit:
sets a two-dimensional partial domain including at least two edge portions of said pattern in an electron beam scanning region,
obstains a plurality of images with different focus conditions by changing focus of an electron beam,
evaluates the plurality of images with different focus conditions in accordance with a sharpness degree of said two-dimensional partial domain, and measures dimension between two edges of one of the images with the highest sharpness degree.
10. A pattern dimension measuring apparatus according to claim 9 , wherein said processing unit carries out image-sharpness-degree evaluation of said two-dimensional partial domain by using said differential filter.
11. A pattern dimension measuring apparatus according to claim 10 , wherein said processing unit determines application direction of said differential filter in accordance with edge forming direction in said two-dimensional partial domain.
12. A pattern dimension measuring apparatus according to claim 11 , wherein when an edge of said two-dimensional partial domain is formed having line segments only in a certain direction, only a differential filter of a perpendicular direction is applied to said line segments.
13. A pattern dimension measuring apparatus including:
a processing unit for measuring dimension of a pattern formed on a sample in accordance with a detection signal detected by a scanning electron microscope, wherein said processing unit:
sets a plurality of two-dimensional partial domains in an electron beam scanning region,
obstains a plurality of images with different focus conditions by changing focus of an electron beam,
evaluates the plurality of images with different focus conditions in accordance with a sharpness degree of said two-dimensional partial domains, and measures dimension between two edges of one of the images with the highest sharpness degree.
14. A pattern dimension measuring apparatus according to claim 13 , wherein said processing unit sets two two-dimensional partial domains in the scanning region of said electron beam, and measures dimension between edges formed in said two two-dimensional partial domains.
15. A pattern dimension measuring apparatus according to claim 13 , wherein said processing unit sets a plurality of two-dimensional partial domains in the scanning area of said electron beam, and measures dimension between two edges at each of said plurality of two-dimensional partial domains.
16. A pattern dimension measuring apparatus according to claim 15 , wherein said image-sharpness-degree evaluation is carried out at each of said plurality of two-dimensional partial domains.