JPS5856947B2 - Electron beam alignment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam alignment device that can perform effective alignment without being affected by the intensity distribution of the electron beam.

In a conventional electron beam alignment device, generally fan-shaped metal electrode blades 1 as shown in FIG.

The deviation of the electron beam was detected from the intensity of the irradiation current of the electron beam detected by each metal electrode blade 1.

However, alignment has been carried out by controlling the electron beam so that the currents detected by the electrode blades 1 are balanced.

However, such alignment is very effective for electron beams whose intensity distribution is approximately symmetrical, such as the electron beam emitted from a tungsten filament electron gun, but for electron beams emitted from a LaB 6 cathode electron gun. radiated J1
Problems occurred with electron beams that had a symmetrical intensity distribution.

That is, when aligning the axis of an electron beam having an intensity distribution as shown in FIG. The center has lost its old name.

In other words, the axis alignment was performed outside the highest intensity region of the electron beam, and the electron beam could not be used efficiently.

Moreover, since the direction indicating the highest intensity region is constantly changing, it is difficult to control the alignment position (2), and at the same time, the intensity changes greatly depending on the angle α in the figure.

The present invention has been made in consideration of these circumstances, and its purpose is to achieve effective axis alignment regardless of the type or form of the electron gun, that is, regardless of the intensity distribution of the electron beam. It is an object of the present invention to provide an electron beam alignment device that can effectively utilize the highest intensity region of the electron beam and easily obtain an electron beam with little change in intensity.

That is, a feature of the present invention is that, for example, as shown in FIG. 2a, the electron beam detection area is formed near the central axis, and electrode blades are formed narrowly in the direction toward the central axis to reduce the deviation of the electron beam. By detecting the electron beam, axis alignment can be performed effectively without depending on the intensity distribution of the electron beam.

The present invention will be described below according to embodiments shown in the drawings.

FIG. 2a shows the metal electrode blade 11 used in the same embodiment.

This electrode blade 11 has a fan-shaped shape with an apex angle of 9G, and its top is notched in an arc shape to match the aperture shape of the electron beam device, and at the same time, the center portion of the blade 11 is bored. .

That is, the narrow inner circular arc portion 11a is connected to the branch portion 11b,
It has a shape connected to the outer circular arc portion 11d via 11c.

The four metal electrode blades 11 having the above shape are arranged with their tops facing each other and electrically separated from each other with a small gap between them.

Thus, the inner arc portions 11a of each electrode blade 11 are opposed to each other to form an annular shape, the center gap thereof coincides with the central axis of the device, and the inner arc portions 11a are supported by the outer arc portions 11d.

The inner arc portion 11a acts as an electron beam detection area.

FIG. 3 is a schematic diagram of an electron beam device constructed using the metal electrode blades 11 described above.

The device emits radiation from an electron gun (not shown), focuses the
) Isometric system 12 for aligning the electron beam directed to the opposite side
is projected onto an aperture 14 via an electron lens 13, and the aperture image is irradiated onto a target 16 via an objective lens 15.

The opposed metal electrode blades 11 form an aperture 14.
The mechanical center axis is placed above the

Information on the intensity of the electron beam detected by the electrode blade 11, that is, information on the deviation, is input to the horse meat circuit 1γ, and the circuit 11 drives the deflection system 12,
The electron beam is directed forward in a direction that corrects the above deviation.

Therefore, only the electron beam that passes through the central gap between the electrode blades 11 and the aperture 14 is irradiated onto the target 16 via the objective lens 15.

In addition, the metal electrode blade 11 detects only the intensity of the electron beam near the central axis in a region that is not exposed to irradiation when the irradiation of the target 11 is originally blocked by the aperture 14 .

According to the device configured in this way, for example, the second
If an electron beam having an intensity distribution as shown in the figure is detected by the electrode blades 11, the detected current will be as shown by the shaded area in the figure.

Then, when the electron beam is moved toward the (2) side so that the detection currents are balanced, the highest intensity region of the electron beam substantially coincides with the mechanical central axis.

In addition, since the intensity distribution in this region is locally approximately uniform,
Accurate alignment is possible without depending on changes in the overall intensity distribution.

At the same time, the electron beam that is irradiated onto the target 11 can be in the highest intensity region, and the electron beam can be used with high efficiency.

In addition, even if there is a direction change in the highest intensity region, unlike conventional equipment, α is an approximate calculation, so high-speed alignment tracking is possible, and the change in the intensity of the irradiated electron beam can always be kept small. I can do it.

Furthermore, when the electron beam having the intensity distribution shown in FIG. 2A is irradiated with a large deviation, the forward action of the electron beam is large, so that the responsiveness of alignment is extremely good.

Moreover, it works extremely well even with electron beams having a substantially symmetrical intensity distribution.

Therefore, even if, for example, the anode-Wehnelt-cathode alignment of the electron gun is slightly out of order, a high-intensity electron beam that is centered can always be stably obtained.

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

For example, in a device having a rectangular aperture, an electrode blade 21 having a rectangular electron beam detection area may be used as shown in FIG.

In addition, since the detection area can be formed narrowly in the direction toward its central axis, the J1 detection area does not have to be hollow.
For example, a grounded annular metal plate may be arranged above the electrode blade 11 so that only the electron beam near the center, which is not used for irradiation, reaches the metal blade 11.

Furthermore, applicable electron beam devices include exposure devices, electron microscopes, and X-ray microanalyzers.
It can be applied to various devices using electron beams and ion beams.

In addition, the means for deflecting the electron beam can also be electromagnetic forward, electrostatic (2)
For example, a conventionally known method may be used.

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

As described in detail above, the present invention detects the electron beam intensity in a very small width region near the central axis in a region that is not subjected to electron beam irradiation, and corrects the deviation of the electron beam by controlling the plane. This is for alignment.

Therefore, as mentioned above, the electron beam has various special advantages, and has the excellent feature of being able to perform effective axis alignment without depending on the intensity distribution of the electron beam, and always irradiating a stable electron beam with the highest intensity. A beam alignment device can be provided.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a metal electrode blade of a conventional structure and its detection function, Fig. 2 is a diagram showing a metal electrode blade of an embodiment of the present invention and its detection function, and Fig. 3 is a diagram showing the entire electron beam device. FIG. 4 is a diagram showing a metal electrode blade according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... Metal electrode blade, 11a... Inner annular part (detection area), 12... Deflection system, 13... Electron lens, 1
4...Aperture, 15...Objective lens, 16...
・Target, 1γ... In-plane control circuit.

Claims (1)

[Claims] 1. A method of detecting a deviation of an electron beam using electrodes arranged opposite to each other with the optical axis as the center, and aligning the electron beam by (2) directing the electron beam in a direction to correct the deviation. An electron beam alignment device characterized in that the electron beam detection area of the electrode is defined at a position near the center axis of the electron beam to be irradiated and has a minute width that is not used for irradiation. 2. The electrode according to claim 1, wherein the electrode is composed of a plurality of metal pieces narrowly formed in the direction toward the optical axis, and these metal pieces are arranged in a ring shape around the optical axis so as to face each other. Electron beam alignment device.