JPH01232650A - Pattern length measuring method - Google Patents

Abstract

PURPOSE:To lessen dispersion in the measurements and enhance the measuring accuracy without dropping the throughput by making a plural set of scannings while the scanned region is moved in the Y direction when a plurality of line scannings are constituting one set of scannings, and by determining average of measurements on the basis of all information signals obtained by these scannings. CONSTITUTION:An electron beam etc., scans on the pattern for a certain distance in the +X direction. After minute movement in the -Y direction, scanning is made in the X direction. Another movement is made in the -Y direction followed by scanning in the + direction, and thus a plurality of line scannings are performed. Plural sets of these scannings are performed with points at certain intervals in the Y direction as the centers, for ex. A, B, C.... The weighted mean M(A) of measurements is determined on the basis of the data obtained from scannings conducted with the point A as the center, and alike the weighted means M(B), M(C) of applicable measurements are determined from the scannings with the points B, C as the centers, and further the mean thereof is determined to provide the final value of measurement.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for determining the ΔPI length of a pattern, and in particular, the present invention relates to a method for determining the ΔPI length of a pattern, and in particular, the present invention relates to a method for determining the ΔPI length of a pattern. [Regarding a pattern 81j method with improved accuracy.

[Prior Art] Methods for measuring the length of a pattern using a charged particle beam include a line scanning method and a raster scanning method. Here, in the line scanning method, as shown in FIG. 4(a), a specific position (a) indicated by an arrow in the pattern P is repeatedly scanned, secondary electrons, etc. are detected by this scanning, and the detected In this method, the positions of both edge portions of the pattern are determined based on the signals obtained, and the width of the pattern is measured. The raster scanning method raster scans a certain area (b) on the pattern P as shown in FIG. In this method, the pattern is lengthened by 7111 points based on this data.

[Problem to be solved by the invention] By the way, in such a pattern 1 PII length method,
The former line scanning method only requires repeated scanning of the predetermined position to be measured, so compared to the latter raster scanning method, the information necessary for length measurement can be obtained more quickly and the throughput can be improved. can be all long. However, in the line scanning method, since the same line is repeatedly scanned, the charge-up of the measurement line increases, resulting in a change in the detection signal.

Furthermore, if there is a slight distortion in the pattern P, since the length is measured only at a specific position of the pattern, the measured values may vary depending on the measurement position, resulting in insufficient length measurement accuracy. On the other hand, in the latter Rascou scanning method, as mentioned above, a certain area is raster scanned and the length is measured by taking the average value of the edge position information obtained from this scanning, so there is a slight distortion in the pattern. It is possible to measure the length without dispersing the measured values even in the case of However, in the latter raster scanning method, since the -window area is scanned, it takes time and reduces throughput.

The present invention has been made in view of the above points, and is a pattern length measurement method that improves length measurement accuracy by reducing variation in measurement values even when there is slight distortion in the pattern without reducing throughput. The purpose is to share the method.

[Means for Solving the Problems] Therefore, in the pattern side length method according to the present invention, a charged particle beam is deflected, a pattern is scanned by the charged particle beam, and a secondary electron signal etc. obtained with the scanning is detected. In the method of measuring the pattern length based on the detected information signal, the pattern is scanned multiple times from different directions while moving the position of the scanning line by a minute distance in the Y direction each time the line is scanned in the X direction. When a line scan is performed across the X direction and the multiple line scans are made into one set of scans, multiple sets of scans are performed while moving the scanning area in the Y direction, and the gain is obtained with these multiple sets of scans. The feature is that the length is measured based on all the information signals received (by calculating the average of the direct measurements).

[Example] The method of the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic configuration diagram showing an example of an electron beam length measuring machine that implements the method of the present invention, in which 1 is an electron gun, 2 is an extraction electrode, 3 is a condenser lens, 4 is an objective lens, 5 is a deflection coil, 6 is a material on which a pattern P is drawn as shown in FIG. 2, 7 is a scanning power source, and 8 is a microcomputer that controls the scanning power source 7. The signal causes the pattern P to be scanned by the electron beam EB. 9 is a detector, 10
1 is a secondary electron, 11 is a signal processing circuit, and 12 is a display device.

In the length measurement method according to the present invention, as shown in FIG. 3, first, an electron beam or the like is scanned over a pattern over a certain distance in the +X-axis direction. Next, after moving a small distance, for example, one step, in the -Y-axis direction, it is then caused to scan a fixed distance in the -X-axis direction. Here, a line is scanned in the X direction across the pattern several times, for example, by moving it one step in the -Y axis direction and scanning in the +X axis direction, and such scanning is combined into one set of scans. As shown in FIG. 2, this kind of scanning is performed roughly in multiple locations such as A, B, C, . . . centering on positions separated by a certain distance in the Y direction. Then, a weighted average of the measurements M (A)
Similarly, by scanning centered on positions B and C, weighted averages of the measured values M (B) and M
(C), and further calculate these average values M (A), M
The average value of (B) and M (C) is determined and used as the final measured value. In this way, measurements are taken at multiple locations along the pattern, and the average value is used as the final measurement value, so that the influence of subtle distortions in the pattern is canceled out, making it possible to reduce variations in the measurement values. Further, since the X-scanning is performed at a plurality of locations in the Y-direction at regular intervals, rather than scanning the entire fixed range in the Y-direction, the throughput is not reduced.

Further, in the present invention, since the line scanning in the X direction is alternately performed from different directions, a detection signal with good symmetry can be obtained, and therefore the accuracy of length measurement data can be improved.

Furthermore, unlike line scanning, charged particles are not irradiated in a concentrated manner at one location, so when displaying a pattern image, it is possible to display an image that is less affected by charge-up.

Furthermore, since the positions are moved forward by a certain distance and lengthened by C1, such as n1 fixed positions A, B, C, etc., the pattern whose longitudinal direction is inclined with respect to the Y direction When measuring the length, the inclination can be corrected by obtaining data representing the distance in the Y direction between these measurement positions and data representing the amount of deviation between AB of the X coordinate of the pattern edge.

[Effects of the Invention] As described in detail above, according to the present invention, in the method of deflecting and scanning a pattern with a charged particle beam and lengthening the pattern 11) based on the information signal generated from the beam,
A pattern δFl length method is provided that improves the nj length accuracy by reducing the variation in measured values even when there is slight distortion in the pattern without reducing the throughput.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an example of an electron beam dP1 long machine that implements the method of the present invention, Fig. 2 is a diagram for explaining an embodiment of the method of the present invention, and Fig. 3 explains the scanning method. FIGS. 4(a) and 4(b) are diagrams for explaining the prior art. 1: Electron gun, 2: Extraction electrode, 3: Condenser lens, 4: Objective lens, 5: Deflection coil, 6: Material, 7: Scanning power supply, 8: Microcomputer, 9: Detector, 10
: Secondary electron, 11: Signal processing circuit, 12: Display device, P
:pattern.

Claims (1)

[Claims] In a method of deflecting a charged particle beam, scanning a pattern with the charged particle beam, detecting a secondary electron signal etc. obtained with the scanning, and measuring the length of the pattern based on the detected information signal, Each time a line scan is performed, the position of the scan line is moved by a minute distance in the Y direction, and line scans are performed in the X direction across the pattern multiple times from different directions alternately, and the multiple line scans are combined into one set. When scanning, multiple sets of scans are performed while moving the scanning area in the Y direction, and the length is measured by calculating the average of the length measurement values based on all the information signals obtained from these multiple sets of scans. A pattern length measurement method characterized by: