LENGTH MEASUREMENT SYSTEM

• US 20090046896A1
• Filed: 08/13/2008
• Published: 02/19/2009
• Est. Priority Date: 08/17/2007
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: YAMAMOTO, Jiro, YAMAGUCHI, Atsuko, KAWADA, Hiroki
• Granted Patent: US 8,369,602 B2
• Time in Patent Office: Days
• US Class Current: 382/106
• CPC Class Codes: G06T 2207/10061 from scanning electron microscope
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/0006 using a design-rule based approach
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes
• CPC Class Codes: G06V 10/44 Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components

Abstract

Disclosed herewith is a length measurement system, which obtains a value closer to its true one when figuring out the size and edge roughness of a pattern from a noise-included pattern image. Among plural band-like regions representing a portion around an edge in an image respectively, the system calculates the dependency of the edge point position on the image processing parameter at each of a narrow width band-like portion and a wide width band-like portion to calculate an image processing condition that calculates each measured value closer to its true value or estimates the true value itself.

Claims

1. A length measurement system capable of figuring out a position of an edge of a pattern by finding the two-dimensional intensity distribution of a signal obtained from a patterned sample through observation by a microscope,

wherein, when an edge of a pattern or the pattern in the two-dimensional intensity distribution is that of a line pattern or the line pattern itself, an image processing is carried out to average the signal intensity for a given portion of the pattern, which includes both right and left edges of the line, by specifying the number of pixels to be averaged in a direction vertical to the edges or line, that is, by specifying a smoothing parameter Sm, then another processing is carried out to calculate the edge position or line width with respect to each of Sm values that are varied sequentially, thereby figuring out the dependency of each object edge position or line width on the Sm value.

2. The length measurement system according to claim 1,

wherein the system is also capable of estimating a value of the edge position or line width by fitting the dependency of the edge position or line width on the edge position or line width smoothing parameter Sm with a function if the averaging is not carried out in the direction vertical to the edge position or line width.

3. The length measurement system according to claim 1,

wherein, in addition to the figuring-out of the dependency of the edge position or line width on the edge position or line width smoothing parameter Sm, the system is also capable of figuring out the dependencies B(Sm) and N(Sm) of the edge position on the Sm parameter with respect the widest band-like region and the narrowest band-like region selected from an inspection region, thereby figuring out a difference between those dependencies B(Sm) and N(Sm), each band-like region being equivalent to an edge of the pattern.

4. The length measurement system according to claim 3,

wherein the widest and narrowest band-like region are selected automatically in the inspection region.

5. The length measurement system according to claim 1,

wherein, in addition to the processing that calculates the dependency of the edge position or line width on the smoothing parameter Sm, the system also includes a processing that calculates how much the outermost noticeable and innermost noticeable edge points in a group of edge points are shifted from the line due to the increase of the Sm value, that is, calculates X_out(Sm) and X_in(Sm), then calculates a difference between the X_out(Sm) and the X_in(Sm).

6. The length measurement system according to claim 3,

wherein the outermost noticeable edge point and the innermost noticeable edge point with respect the line are selected automatically.

8. The length measurement system according to claim 3, wherein the system further capable of carrying out fitting for a set of data (Sm, R(Sm)) with a function y=p(B(x)−

N(x))+r or y=p|X_out(x)−

X_in(x)|+r that assumes p and r as fitting parameters, thereby figuring out the edge roughness or line width roughness when no averaging is carried out in a direction vertical to the edge or line.

9. The length measurement system according to claim 4, wherein the system further capable of carrying out fitting for a set of data (Sm, R(Sm)) with a function y=p(B(x)−

N(x))+r or y=p|X_out(x)−

X_in(x)|+r that assumes p and r as fitting parameters, thereby figuring out the edge roughness or line width roughness when no averaging is carried out in a direction vertical to the edge or line.

10. The length measurement system according to claim 5, wherein the system further capable of carrying out fitting for a set of data (Sm, R(Sm)) with a function y=p(B(x)−

N(x))+r or y=p|X_out(x)−

X_in(x)|+r that assumes p and r as fitting parameters, thereby figuring out the edge roughness or line width roughness when no averaging is carried out in a direction vertical to the edge or line.

11. The length measurement system according to claim 6, wherein the system further capable of carrying out fitting for a set of data (Sm, R(Sm)) with a function y=p(B(x)−

N(x))+r or y=p|X_out(x)−

X_in(x)|+r that assumes p and r as fitting parameters, thereby figuring out the edge roughness or line width roughness when no averaging is carried out in a direction vertical to the edge or line.

7. A length measurement system capable of figuring out an edge position of a pattern by finding the two-dimensional intensity distribution of a signal obtained from a patterned sample through observation by a microscope,

wherein the system is also capable of figuring out a standard deviation σ

or an “

n”

multiple of the standard deviation σ

with respect to the distribution of a deviation from edge roughness, that is, an ideal shape of the edge position or capable of figuring out the standard deviation σ

or an “

n”

multiple of the standard deviation σ

with respect to the line width roughness, that is, the distribution of the local line width when the pattern is a line pattern; and

wherein the system carries out an image processing first to average the signal intensity by specifying the number of pixels Sm used for averaging in a direction vertical to an object edge or line with respect to a given portion that includes one or both edges of the pattern in the two-dimensional intensity distribution, then carries out a processing that calculates the edge roughness or line width roughness with respect to each of Sm values to be varied sequentially, thereby figuring out the dependency R(Sm) of the edge roughness or line width roughness on the Sm value.