Pattern measuring apparatus
a technology of pattern size and measuring device, which is applied in the direction of material analysis using wave/particle radiation, instruments, nuclear engineering, etc., can solve the problem of unsuitable use for accurate measurement of pattern siz
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embodiment 1
[0028]In the embodiment below, an example will be described which tilts an electron beam within an area different from the measurement object (i.e., area unused for length measurement) in the process of acquiring a length measurement image that is subjected to pattern measurement and uses the information to be obtained based on irradiation of such tilted beam to perform concavity / convexity determination. By the beam tilting, the electron beam is caused to hit one side-wall of a circuit pattern rather than its top surface; so, this sidewall increases in width of white band when compared to top-down images. As the white band varies in width in a way depending on a tilt angle of the electron beam, it becomes easier to specify an edge on one side with the white band getting thick. A sidewall onto which the electron beam is irradiated is a sidewall of convex portion. Thus, if this edge is specifiable, it becomes possible to specify the positions of convex and concave portions with respec...
embodiment 2
[0055]An explanation will next be given of an example which performs concavity / convexity determination of a workpiece or sample wafer by a technique other than the beam tilt method, which utilizes the swing-back action of an objective lens. FIG. 9 is a diagram showing part of an optics system of SEM including a couple of scrolling deflectors 901 and 902.
[0056]Although these scrolling deflectors 901-902 are for deflecting a beam while letting an intersection of a principal plane of objective lens 806 and an ideal light axis 802 be a supporting point of deflection, another arrangement may be employed which supplies the deflector with a signal with superimposition of a 2D beam scanning signal to thereby perform the view field movement and the deflection for beam scanning. Alternatively, the scanning deflector 104 and the scrolling deflectors 901-902 may be provided separately.
[0057]FIG. 10 is a diagram showing an example with setup of a length measurement object area 1002 and concavity...
embodiment 3
[0071]The above-stated pattern distinguishing method using a tilted beam is employable not only for convexo-concave patterns, such as line-and-space patterns, but also for the specifying of circuit patterns that are fabricated by self-alignment double patterning (SADP) techniques.
[0072]FIG. 6 shows a cross-sectional view of a pattern in SADP process step. A circuit pattern formed by the SADP process has multiple line segments, two adjacent ones of which make one set together in compliance with manufacturing process rules. This means that linear circuit pattern segments having the same cross-sectional shape appear alternately. For this reason, in order to measure pattern sizes properly, it is required to identify the period λ of circuit pattern accurately. In FIGS. 7A to 7C, projection waveforms in Y-direction are shown, which are obtained when SADP-fabricated pattern is image-sensed while changing the tilt angle of an electron beam from zero to −θ and to +θ. By changing the beam til...
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