JPS62144010A - Electronic beam length measuring apparatus - Google Patents

Abstract

PURPOSE:To make it possible to automatically measure the length of an objective pattern even when the pattern to be subjected to the measurement of a length is close to each other, by also simultaneously displaying a marker processing the primary electron signal wave form from the pattern. CONSTITUTION:The electron image from the pattern of a wafer is generated by scanning due to the irradiation of electron beam to be detected by a detector 23. The detection output is processed by an A/D converter 26, a signal extraction circuit 28 having a memory mounted therein and a processing circuit 30 and the wave form corresponding to the width length of the pattern is displayed on a wave form/marker display apparatus 29. Markers 32, 33 set by a marker setting circuit 31 are also displayed on said apparatus 29 and, corresponding to the primary electron output signal between the markers, the discrimination between said signal and the secondary electron output signal from the adjacent pattern can be performed and, even when a pattern to be subjected to the measurement of a length is close, the length of an objective pattern can be automatically and surely performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electron beam device with a length of 1 lllll, and in particular to a
The present invention relates to an electron beam i11'l length device that is effective when +'1 length patterns are in the vicinity.

[Background of the invention]

In automated electron beam length measurement equipment.

Covered? Secondary electron image of liq length pattern? A method is adopted in which the length can be measured while being observed by a 1++1 measurer, and the waveform signal obtained when the pattern to be measured is one-dimensionally scanned with an electron beam is automatically processed. That is, this method compares the detection signal with an arbitrary comparison level, detects the position where the signal crosses the comparison level, and calculates the pattern dimension from the position data.

FIG. 1 illustrates this method. When a pattern 11 formed on a sample 10 is scanned with an electron beam 12, a signal 13 as shown in FIG. 2(b) is detected. Next, the signal 13 is compared with the comparison level 14, and the point at which the signal 13 crosses the comparison level 14, t11.5.16, is detected. Since positions 15 and 16 correspond to both ends of the pattern 11, the dimensions of the pattern 11 are calculated from this position data.

Although it is possible to measure pattern dimensions by the above method, there are problems described below when measuring the length of an actual pattern of a semiconductor element. That is, as shown in FIG. 1(c), in an actual semiconductor device, the patterns are very close to each other, and the signals detected by electron beam scanning include not only the target pattern but also signals from adjacent patterns. is also often detected. In such a case, in conventional processing, obtaining the desired pattern dimensions was repeated.

Note that the positioning method in the electron beam device is disclosed in, for example, Japanese Patent Laid-Open No. 59-207554.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dimension measuring apparatus using an electron beam that can measure the length of a target pattern even when the patterns to be measured are close to each other.

[Summary of the invention]

The length measuring device according to the present invention has a function of extracting only the portion of the signal from the target pattern from the detected signal. That is, it is equipped with a display device that displays the detection signal and also superimposes a marker for limiting the processing range, and by extracting the necessary portion by limiting the position of the marker to an appropriate position, it is possible to achieve the target. Pattern length measurement becomes possible.

[Embodiments of the invention]

The present invention will be explained below with reference to Examples.

FIG. 2(a) is a block diagram of an electron beam tIq length apparatus embodying the present invention. A pattern formed on a Si wafer 21 provided on a sample stage 23 is scanned by an electron beam 2o, and a secondary electron signal from the pattern is detected by a detector 23. The detected secondary electronic signal is digitized by the A/D converter 26, recorded in the memory in the circuit @28, and displayed on the display device v129. Since the deflection range of the electron beam 2o is 50 μm, length measurement over the entire surface of the Si wafer 21 is performed by secondarily moving a good sample to the sample stage 22.

The sample stage 22 is controlled by a control circuit 27, and the position detection accuracy of the sample stage 22 is 0.01 μm. Further, the deflection of the electronic beam 11 was performed digitally by a deflection amplifier 25 and a deflector 24, and the accuracy was adjusted to 0.005 μm/step.

When adjacent patterns on the first chip on the Si wafer 21 were measured, three patterns were found within the deflection region of the electron beam, as shown in FIG. 2(b). The signal waveform displayed on the display device 29 in this case is shown in FIG. 2(c).
Indicated by

In the figure, the vertical axis is the signal intensity, and the horizontal axis is 0.005 μm.
The beam is deflected in increments, and the center is the position where the amount of deflection is 0 μm.

8111 Since the pattern to be determined was the central pattern, the marker 32, which is displayed weighted on the signal waveform,
3:3 position by operating the marker measurement circuit 31 as shown in Figure 2 (
c) was determined as follows.

The processing device 30 stores the positions of both markers and stores the positions of both markers as shown in FIG. 2(d).
In particular, only the data between both markers is extracted, and the extracted data 40 is compared with the comparison level 41 to find the intersection 42.
．． 43 is obtained, and the pattern dimension is calculated from the distance between these two points.

For the second and subsequent chips as well, the processing device 30 processes only the data in the stored markers 32 and 33 to obtain pattern dimensions.

〔Effect of the invention〕

According to the present invention, a signal from a target pattern can be extracted even if there are patterns that are very close to each other, and the dimensions of a predetermined pattern can be accurately measured even during automatic length measurement.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the relationship between the length pattern to be measured and the secondary multiplex signal, and FIG. 2 is an illustration of the electron beam 81 based on the present invention.
FIG. 2 is a configuration diagram of a lengthening device and an explanatory diagram showing a secondary electron signal. 10... Sample, 11... Length measurement pattern, 12...
- Electron beam, 13... Secondary electron signal, 2o... Electron beam, 21... Sj wafer, 22... Sample stage,
23... Detector, 24... Deflector, 25... Deflection amplifier, 26... A/D converter, 27... Sample stage control circuit, 28... Signal extraction circuit, 29... ...Waveform and marker display device, 30...Processing Fig. j (α) Fig. 2 <4)

Claims (1)

[Claims] 1. In an electron beam length measuring device consisting of a circuit for scanning a pattern formed on a sample with an electron beam, a circuit for detecting a primary electron signal from the pattern, and a circuit for processing the detection signal to obtain the pattern dimensions, An electron beam length measuring device comprising a display device that simultaneously displays a secondary electron signal waveform from a pattern and a marker for limiting the processing range of the waveform.