JPH0760660B2 - Electron beam equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam apparatus such as an electron beam drawing apparatus, which is required when exchanging a cathode for generating an electron beam and when starting up the apparatus after overhaul. Efficiently adjust the electron gun
The present invention relates to an electron beam apparatus that can be easily performed.

[Background of the Invention]

In an electron beam apparatus such as an electron beam drawing apparatus, which has recently been attracting attention, it is indispensable to overhaul the apparatus, replace the electron gun cathode, and perform regular maintenance work. With these maintenance work, in order to reproduce a predetermined electron beam intensity, a fluorescent plate arranged at several places in the electron beam passage,
Alternatively, observation of a backscattered electron image by an electron beam irradiated on an arbitrary sample surface and complicated optical axis adjustment operation are required. Particularly, in a drawing apparatus using an area beam, it is necessary to uniformly cover the entire diaphragm having a rectangular cross section (about 100 μm ^□ ) and adjust the electron gun unit so that the maximum electron beam intensity can be obtained. Conventionally, these operations are limited to skilled engineers, and in the case of a drawing apparatus having a long lens barrel, the experience and intuition have been a major factor. Therefore, an adjustment method that simplifies the adjustment of the electron gun and can perform it efficiently has been desired.

On the other hand, there is a method disclosed in Japanese Patent Application Laid-Open No. 56-6363 as an adjusting method after replacement of the electron gun cathode, but generally, in the area beam type drawing apparatus using the electron gun cathode having a wide radiation angle distribution, the maximum beam intensity The position of the obtained electron gun has to be found within a wide two-dimensional electron beam emission region, and the improvement in this respect has been insufficient.

[Object of the Invention]

The present invention is intended to compensate for the above-mentioned conventional drawbacks, and an object of the present invention is to provide an electron beam apparatus capable of more easily adjusting an electron gun.

[Outline of Invention]

The present invention mainly relates to application to an area beam type electron beam drawing apparatus having a rectangular cross section, and always irradiates the entire rectangular diaphragm that is the root of the rectangle uniformly and maintains the maximum electron beam intensity stably. It is what makes it possible to do.

In order to achieve the object of the present invention, in the present invention, an electron gun section, a limiting diaphragm provided on a path of an electron beam generated from the electron gun section, and a wide range of X-rays of the electron beam on the limiting diaphragm.
-Deflection means for deflecting and scanning the Y plane, a detector for measuring the intensity of the electron beam penetrating the aperture of the diaphragm, and control means for supplying the detection signal to the deflection section through a computer. The deflection scanning position corresponding to the maximum electron beam intensity found from a series of deflection scanning of the electron beam is fed back to the deflection means by the control means based on the detection signal to stabilize the maximum electron beam intensity. It is something to maintain.

Example of Invention

 Hereinafter, the present invention will be described in detail based on examples.

In FIG. 1, 1 is an electron gun cathode, 2 is a Wehnelt electrode, and 3 is an anode. The cathode 1 is heated to an optimum temperature in advance (about 1500 ° C. in the case of LaB ₆ cathode), and a bias voltage is applied between the cathode 1 and the Wehnelt electrode 2 by a bias power source (not shown). On the other hand, when an acceleration voltage of several tens of kV is applied between the cathode 1 and the anode 3, the electron beam 4 is emitted from the surface of the cathode 1 in the direction shown in the figure. The electron beam 4 has a radiation angle (divergence) 2θ peculiar to the shape of the cathode 1, and the deflector 13 can deflect and scan an arbitrary XY plane area on the diaphragm 5. Generally, in an area beam drawing apparatus having a rectangular cross section, a cathode with a larger θ is desirable because it uniformly illuminates the entire hole of the rectangular diaphragm 14 in the figure. Now then, in the deflector 13,
Computer 9 → Interface 10 → D / A converter 11 → Amplifier 1
Control currents I _x and I _y for deflecting the electron beam 4 in a wide range of X and Y directions are independently supplied via 2. Furthermore, the electron beam 4 can reach the detector 6 only when it passes through the opening of the limiting diaphragm 5 provided on its path. The detection signal is stored in the memory of the computer 9 via the amplifier 7 → A / D converter 8 → interface 10 in association with the deflection amounts I _x and I _y . Incidentally, the detector 6 can be moved in and out in the direction of the arrow (x direction) shown in the drawing as required, and the rectangular diaphragm 14 arranged directly below the detector 6 can also be irradiated with a beam. ing.

FIG. 2 shows each control current I in the X and Y directions by the deflector 13.
Measured electron beam intensity (beam current for _x , I _y
The two-dimensional distribution of the I _B) expressed by the schematic diagram. That is, after the deflection scanning area A of I _x and I _y is divided at arbitrary intervals, for example, on the X side.
While moving from P ₀ to P _x , I _B is sequentially measured by the detector 6. Next, after moving one step in the Y direction from P _x ,
Similarly, I _B is measured again in the direction of returning from P _X to P ₀ .
By repeating such zigzag deflection scanning, the distribution shown in FIG. 2 in the arbitrary region A is obtained (actually, the I _B value measured on the two-dimensional plane of I _x and I _y may be recorded). There may be multiple peak points (I _B0 ′, I _B1, etc.) in the distribution map, but the cause is mainly due to insufficient heating of the cathode. In this case, the unnecessary peak point I _B1 (<I _B0 ′) in the figure disappears due to the addition of heating conditions, and the only peak point I _B0 (> I _B0 ′: This is because the cathode temperature rises slightly. , I _{B is} also increased) so that the heating conditions and the like can be set again.

The operator then gives a command to the computer 9 in FIG.
The control currents I _x0 and I _Y0 corresponding to the maximum point I _B0 may be supplied from the memory of the computer 9 to the deflector 13 via the path such as the D / A converter 11 in FIG. These I _x0 and I _Y0 are stably held for a necessary time unless there is a change instruction. The above series of scans can all be automatically performed within a few minutes.

Such two-dimensional deflection scanning of the deflector 13 is very effective in setting the maximum current density in an area beam device that uses a cathode having a wider emission angle distribution than in a dot beam writing device.

Further, in the drawing apparatus using the area beam, there is a restriction that the entire rectangular diaphragm having a predetermined size should be irradiated with a uniform current density. That is, in FIG. 2, for example, a portion having a current density corresponding to 95% of the maximum peak point I _B0 is I
means a region R which is projected radiation onto _x -I _y plane. The size of the region R can be easily visually observed by connecting a display device having a graphics function in the vicinity of the computer 9 shown in FIG.

〔The invention's effect〕

As described above, according to the present invention, it is possible to find the point of maximum beam intensity from a wide radiation angle distribution within a few minutes as compared with the conventional several hours. Therefore, the versatility of the adjustment of the electron gun is increased, which can greatly contribute to the improvement of the operation rate of the device. Further, if the measuring function of the present invention is used as a diagnostic function associated with exhaustion of the electron gun cathode, it is also possible to monitor the planar position variation of the maximum beam intensity point.

Further, in the present invention, the area beam type writing apparatus has been mainly described as an example, but the present invention can be applied to a point beam writing apparatus and other similar electron beam apparatuses.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the operation principle of the present invention, and FIG. 2 is a diagram showing an example of a two-dimensional distribution of beam current detected based on the radiation angle distribution of the electron gun cathode. 1 ... Electron gun cathode, 2 ... Wehnelt electrode, 3 ... Anode, 4 ... Electron beam, 5 ... Limiting aperture, 6 ... Detector, 7,12 ... Amplifier, 8 ... A / D conversion Instrument, 9 ... Calculator, 10 ... Interface, 11 ... D / A converter, 13 ...
… Deflector, 14 …… Rectangular diaphragm.

Claims (4)

[Claims] 1. An electron source for emitting an electron beam, a deflection means for two-dimensionally deflecting the emission direction of the electron beam emitted from the electron source, and an emission angle of the electron beam emitted from the electron source. Intensity distribution measuring means for measuring a two-dimensional intensity distribution in the inside, and a deflection amount for controlling the deflection amount of the electron beam by the deflecting means according to the two-dimensional intensity distribution of the electron beam measured by the intensity distribution measuring means. An electron beam apparatus comprising: a control unit. 2. An electron source for emitting an electron beam, a diaphragm plate arranged in front of the electron beam from the electron source in a radiation direction and having a predetermined electron beam passage opening, and between the electron source and the diaphragm plate. Deflection means arranged to deflect the emission direction of the electron beam emitted from the electron source two-dimensionally, and intensity distribution measurement for measuring the two-dimensional intensity distribution of the electron beam emitted from the electron source within its emission angle. Means and deflection amount control means for controlling the deflection amount of the electron beam by the deflection means according to the two-dimensional intensity distribution of the electron beam measured by the intensity distribution measuring means. Electron beam device. 3. The deflection amount control means is arranged so that the beam portion having the maximum beam intensity within the emission angle of the electron beam passes through an electron beam passage opening provided in the diaphragm plate. The electron beam apparatus according to claim 2, characterized in that the deflection amount of the electron beam according to (3) is controlled. 4. A step of measuring a two-dimensional intensity distribution of an electron beam emitted from an electron source within its entire emission angle, and a maximum beam intensity of the electron beam based on the measurement result of the two-dimensional intensity distribution. Adjusting the beam axis of the electron beam from the electron source so that the beam portion having the beam passes through a diaphragm aperture provided at a predetermined position. Method.