JPS584314B2 - Electron beam measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam measuring device that can accurately measure, for example, the diameter of an electron beam, the magnitude and direction of astigmatism, and the like.

When exposing an IC mask pattern with an electron beam, it is necessary to accurately grasp the diameter and focal position of the electron beam.

Conventionally, for this type of measurement, a Faraday cup is used to measure the beam current, or the electron beam irradiated to the detector is deflected and reflected/secondary electrons or absorbed current from the detector is measured to determine the change in the beam current. I was looking for the percentage.

However, as will be described later, the conventional device has the disadvantage that accurate measurements cannot be made because the cross-sectional shape of the detector is not sharp and there are undulations in the cut surface.

The present invention was made in consideration of these circumstances, and its purpose is to improve the shape of the detector so that the electron beam intensity distribution can be detected and measured sharply and accurately. It is an object of the present invention to provide an electron beam measuring device that enables the above to be easily and accurately carried out.

Hereinafter, one embodiment of the apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of the apparatus, and the dashed line in the figure indicates the electron beam used for measurement.

This electron beam is emitted from, for example, an electron gun, shaped through an aperture, and focused through a condenser lens.

The deflection is controlled by the electric field between the deflection plates 2 to which a deflection voltage is applied by the deflection control device 1.

The electron beam whose deflection has been controlled in this manner is irradiated onto the Faraday cup 3, and the electron beam current is measured by a meter 4.

The upper end surface of the Faraday cup 3 is set at the same height as the exposure surface of an object to be exposed (not shown) to be exposed with an electron beam, for example.

Further, a detector 5 is provided on the upper end surface of the Faraday cup 3 via an insulating layer.

In conventional devices, this detector 5 is made of a thin metal wire or made into a mesh.

The apparatus of the present invention is used here, for example, a silicon single crystal cracked open and coated with gold.

An ammeter 6 is connected to this detector 5 to measure the absorbed current of the irradiated electron beam.

Further, above this detector 5, a semiconductor electronic detector 7 is arranged.

This semiconductor electron detector 7 captures and detects the reflected electrons and secondary emitted electrons from the detector 50 caused by the irradiated electron beam.

This detection signal is amplified to a predetermined level via an amplifier 8 and input to a recorder 9.

This recorder 9 is composed of, for example, an X-Y recorder, and records the detected value in correspondence with the deflection width information from the deflection control device 1.

In such a device, if the electron beam is deflected and the detector 5 is gradually irradiated from the outer edge of the electron beam,
Reflected secondary electrons and absorbed current increase according to the intensity distribution of the electron beam.

Therefore, the electron beam intensity (beam current: ■) detected by the semiconductor electron detector 7 changes as shown in FIG.

Here, the rise characteristic Δx indicates the rate of change in beam intensity at the outer edge of the electron beam.

In other words, the shorter the rise Δx, the sharper the electron beam.

The part where the intensity distribution of the electron beam is the sharpest is the focal position, and therefore the focal position of the electron beam can be observed from the measurement of the intensity distribution.

If we consider the detector used in the conventional device, this detector is formed of a member made by cutting a thin metal wire.

For this reason, the shape of the cut portion of the edge has always been rounded, as shown in FIG.

Moreover, the straightness of the edge portion was poor and the shape was uneven.

Due to this shape, detection errors increased and measurement detection accuracy decreased.

Therefore, the apparatus of the present invention uses the following detector 5.

That is, by using a silicon single crystal, a germanium single crystal, or the like as a detection member and using the crystal cleavage plane as an edge, a detector 5 having a sharp end face shape with good linearity is obtained.

FIG. 4 shows an example of this, where "a" forms an edge with the (100) plane as the main surface.

In this case, the edge is perpendicular to the (100) plane and has extremely high linearity, and the (111) plane is the principal plane in FIG.

In this case, a sharp edge with an angle of about 60° is obtained, and the straightness is also good.

Furthermore, when a single crystal of silicon or germanium is used, there is no charge-up due to the electron beam, making it extremely preferable as a detector.

In the device of the present invention, the surface of the detector 5, that is, the single crystal, is further thinly coated with a heavy metal such as gold, platinum, tungsten, or molybdenum to form a conductive thin film layer.

It was confirmed that this conductive thin film layer increased the reflected electron efficiency and secondary electron emission efficiency for the electron beam, and that detection with a good S/N ratio could be performed.

As described above, if the detector 5 according to the present invention is used, the edge surface is not rounded, that is, it is sharp, and the linearity of the edge is very good, so there is no error factor like in the conventional device. It never becomes.

Therefore, the state of the electron beam can be detected extremely accurately, and highly accurate measurements can be performed.

Moreover, the purpose can be achieved simply by replacing the detector of the conventional device, and the effect is tremendous.

Next, an example of application of the device of the present invention will be explained.

FIG. 5 shows the main part thereof, in which three detectors 5a, 5b, and 5c are arranged on the upper surface of the Faraday cup 3 so as to form an angle of 60 degrees with each other.

The detectors 5a, 5b, and 5c are arranged on the surface of a silicon single crystal with a (110) plane as its main surface, especially on the cleavage plane.
It was deposited to a thickness of 0.00 Å.

The Faraday cup 3 is connected to the XY cup via an insulator.
It is placed on a table (none of which is shown), and its upper surface is set at the same height as the surface of the object to be exposed.

With such a structure, it is possible to accurately detect the focusing degree of the electron beam by measuring the electron beam mentioned above, and by feedback controlling the lens system based on the detection result, it is possible to easily and accurately achieve focusing. It can be carried out.

In addition, the magnitude and direction of astigmatism can be easily detected by deflecting the electron beam in a direction perpendicular to the edge direction of the detectors 5a, 5b, and 5c arranged in three directions. can do.

By feeding back this detection result, astigmatism can also be easily corrected.

Furthermore, the electron beam diameter can be measured accurately and can be effectively used as control information when setting the electron beam diameter to be variable.

Therefore, it is effective as an automatic control system for various electron beam devices.
For example, it is possible to automate and save labor by applying it to an electron beam exposure device.

In this way, according to the present invention, the state of the electron beam is simplified,
In addition, it can be measured with high precision and has great effects.

Note that the present invention is not limited to the above embodiments.

For example, other semiconductor single crystals, ionic crystals, etc. can also be used as the single crystal material.

In short, a detector in which an edge portion is formed using a crystal cleavage plane may be used.

Further, the conductive thin film may be provided as necessary, and its thickness etc. may be determined according to specifications.

Moreover, there is no need to use a Faraday cup for measurement, and it is also possible to simply measure the absorbed current using the detector 5.

In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the device of the present invention, and FIG.
Figure 3 shows the measurement detection characteristics, Figure 3 shows the edge shape of a conventional detector, Figure 4 shows the edge shape of the detector according to the present invention, and Figure 5 shows an example of application of the device of the present invention. FIG. 2... Trend board, 3... Faraday cup, 4, 6... Ammeter, 5, 5a, 5b, 5c
...Detector, 7...Semiconductor electronic detector, 9...Recorder.

Claims (1)

[Scope of Claims] 1. An electron beam detector consisting of a single crystal or a crystal member whose surface is coated with a conductive thin film, the end face of which is a wall opening of the crystal, and an electron beam detector that is irradiated to the electron beam detector. an electron beam measuring device comprising means for measuring the electron beam intensity distribution from reflected secondary electrons or absorption current of the electron beam by the detector. 2. Claim 1, wherein the single crystal is a semiconductor single crystal made of silicon or germanium, or an ionic crystal, and the conductive thin film formed by coating is a heavy metal made of gold, molybdenum, or tungsten. electron beam measuring device.