Measurement system and measurement method

Patent metadata

Field	Value
Publication number	US-2017047197-A1
Application number	US-201515305740-A
Country	US
Kind code	A1
Filing date	Apr 21, 2015
Priority date	Apr 25, 2014
Publication date	Feb 16, 2017
Grant date	—

Abstract

For scanning electron beams and measuring overlay misalignment between an upper layer pattern and a lower layer pattern with high precision, electron beams are scanned over a region including a first pattern and a second pattern of a sample, the sample having the lower layer pattern (the first pattern) and the upper layer pattern (the second pattern) formed in a step after a step of forming the first pattern. The electron beams are scanned such that scan directions and scan sequences of the electron beams become axial symmetrical or point-symmetrical in a plurality of pattern position measurement regions defined within the scan region for the electron beams, thereby reducing measurement errors resulting from the asymmetry of electric charge.

First claim

1 . A measurement system comprising:
a condition setting unit determining a scan direction or scan sequence condition on the basis of a preset arbitrary axis or point within a scan region; an image processing unit adding up regions symmetrical with each other within the scan region in an image obtained by scanning charged particle beams over a substrate having a first pattern and a second pattern formed in a step after a step of forming the first pattern, the scanning being performed on the basis of the scan direction or scan sequence condition determined by the condition setting unit; and an arithmetic unit computing, on the basis of the addition result, an overlay between the first pattern and the second pattern formed in the step after the step of forming the first pattern on the substrate.

2 . The measurement system according to claim 1 , wherein
relative positions of the first pattern and the second pattern in X and Y directions are measured from the addition result.

3 . The measurement system according to claim 1 , wherein
relative positions of the first pattern and the second pattern in X and Y directions are measured from the addition result, and electron beams are scanned such that scan directions and scan sequences of the charged particle beams are point-symmetrical in a plurality of pattern position measurement regions defined within the scan region for the charged particle beams.

4 . The measurement system according to claim 1 , further comprising a display section displaying an operation screen related to creation of the scan condition, wherein
a symmetry axis or a center of point-symmetry related to scan directions and scan sequences of the charged particle beams is displayed on the display section.

5 . The measurement system according to claim 1 , further comprising an output section displaying a measurement result, wherein
the measurement result of each of a plurality of pattern position measurement regions defined within the scan region for the charged particle beams is displayed on the output section.

6 . The measurement system according to claim 1 , wherein
the condition setting unit determines the setting of the axis or the point on the basis of pattern layout information on the first pattern and the second pattern.

7 . A measurement method comprising:
a condition setting step of determining a scan direction or scan sequence condition on the basis of a preset arbitrary axis or point within a scan region; an image processing step of adding up regions symmetrical with each other within the scan region in an image obtained by scanning charged particle beams over a substrate having a first pattern and a second pattern formed in a step after a step of forming the first pattern, the scanning being performed on the basis of the scan direction or scan sequence condition determined by the condition setting unit; and an arithmetic step of computing, on the basis of the addition result, an overlay between the first pattern and the second pattern formed in the step after the step of forming the first pattern on the substrate.

8 . The measurement method according to claim 7 , wherein
the arithmetic step includes measuring relative positions of the first pattern and the second pattern in X and Y directions from the addition result.

9 . The measurement method according to claim 7 , wherein
the condition setting step includes: measuring relative positions of the first pattern and the second pattern in X and Y directions from the addition result; and scanning electron beams such that scan directions and scan sequences of the charged particle beams are point-symmetrical in a plurality of pattern position measurement regions defined within the scan region for the charged particle beams.

10 . The measurement method according to claim 7 , further comprising a display step of displaying an operation screen related to creation of the scan condition, wherein
the display step includes displaying a symmetry axis or a center of point-symmetry related to scan directions and scan sequences of the charged particle beams.

11 . The measurement method according to claim 7 , further comprising an output step of displaying an overlay computation result, wherein
the output step includes displaying a measurement result of each of a plurality of pattern position measurement regions defined within the scan region for the charged particle beams.

12 . The measurement method according to claim 7 , wherein
the condition setting step includes determining the setting of the axis or the point on the basis of pattern layout information on the first pattern and the second pattern.

Assignees

• Hitachi High Tech Corp

Inventors

• Hotta Shoji
• Kawada Hiroki
• Inoue Osamu

Classifications

• G06T2207/30148

  Semiconductor; IC; Wafer · CPC title

• G03F7/70633

  Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching · CPC title

• H01J2237/2817

  Pattern inspection · CPC title

• G03F9/7061

  Scanning probe microscopy, e.g. AFM, scanning tunneling microscopy · CPC title

• G06T7/66

  of image moments or centre of gravity · CPC title