JPS5953657B2 - electron beam equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam device with a simple configuration that can obtain an electron beam with stable image position and intensity.

In recent years, high brightness and long life LaB has been developed.

Electron beam devices using electron guns have come into widespread practical use. However, the above LaB. The electron beam emitted from the electron gun generally has a problem in that the crossover position tends to fluctuate, and the radiation distribution angle (intensity distribution) also tends to fluctuate. This is because the aperture is shaped through the
The intensity of the electron beam focused through the electron lens and irradiated onto the target was unstable, and the irradiation position was also unstable. Conventionally, attempts have been made to dispose a deflection system below the electron gun and eliminate the above-mentioned unstable factors based on information on the deviation of the electron beam. However, there was a problem in that if the electron beam intensity was stably controlled, the beam position would fluctuate, and conversely, if the beam position was stably controlled, the intensity would fluctuate. For this reason, LaB has advantages as described above. It was extremely difficult to use the electron gun effectively. The present invention has been made in consideration of these circumstances, and its purpose is to provide an electron beam device that can stabilize the intensity of the electron beam without causing instability in the irradiation position of the electron beam. We aim to realize and provide this.

That is, the present invention provides the following for the Kohler irradiated electron beam:
It is an object of the present invention to provide an electron beam device capable of correcting variations in the diagonal distribution of the beam without causing any variations in the position of the crossover image of the electron beam.

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

FIG. 1 is a schematic configuration diagram of the apparatus.

For example, an electron beam emitted from an electron gun 1 consisting of a LaB6 cathode forms a crossover image a near the electron gun 1, and then forms a crossover image a through a condenser lens 2. is illuminated onto the beam shaping aperture 3 of.

The image of this aperture 3 is transmitted to the first and second projection lenses 4,
5 onto a second beam shaping aperture 6. Incidentally, by controlling the deflection of the electron beam projected from the first beam shaping aperture 3 to the second beam shaping aperture 6, variable dimension shaping of the electron beam is performed. The image of the shaped electron beam is then reduced and projected onto the target 9 through the reduction lens 7 and further through the objective lens 8. On the other hand, a metal electrode 11 for detecting the deviation of the electron beam is arranged coaxially with the aperture 3 above the first beam shaping aperture 3 .

The metal electrode 11 detects the intensity of the peripheral region of the electron beam that is not irradiated to the aperture 3 and detects the deviation of the electron beam, and the detected information is input to the deflection control device 12. This deflection control device 12 drives a deflection coil 13 provided near the position of the crossover image a to deflect the electron beam using the position of the crossover image a as a fulcrum. Further, a metal electrode 14 is coaxially arranged near the upper position of the objective lens 8, that is, near a crossover image b formed at the center of the objective lens 8.

This metal electrode 14 is used to detect a positional shift of the crossover image b, and the detected information is input to the deflection control device 15. Then, this deflection control device 15
A deflection coil 16 disposed coaxially with the beam shaping aperture 6 is driven to deflect the electron beam about the aperture position C as a fulcrum. When analyzing the unstable elements of the electron beam focused on the target 9 in the apparatus, that is, the optical system, configured as described above, it can be classified into two types as follows.

One is that the position of crossover image a changes due to changes in the crossover position. Therefore, the position of the enlarged crossover image b formed on the objective lens 8 changes. As a result, the amount of the electron beam passing through the aperture of the objective lens 8 fluctuates, and the beam intensity fluctuates, that is, becomes unstable. On the other hand, electronic. gun 1
The radiation angle distribution of the electron beam emitted from the beam may vary. In this case, the intensity distribution of the electron beam irradiated onto the first beam shaping aperture 3 becomes non-uniform, and therefore the intensity distribution of the electron beam projected onto the target 9 becomes non-uniform. In other words, the position of the illuminated electron beam becomes unstable, resulting in so-called unevenness of the electron beam image. Therefore, in this device, in order to deal with the former instability, the metal electrode 14 is placed near the objective lens 8, as described above, and this is done to prevent the fluctuation of the crossover image a position due to the fluctuation of the crossover position of the electron beam. The positional fluctuation of crossover image b is detected.

Then, the deflection coil 16 provided at the position of the aperture 6 is driven to deflect the electron beam, thereby compensating for the variation in the position of the crossover image a. In this case, since the electron beam is deflected using the position of the aperture 6 as a fulcrum, there is no change in the position of the electron beam on the target 9. In other words, it is possible to independently compensate for fluctuations in the position of the crossover image and obtain an electron beam with stable intensity at all times. On the other hand, for the latter instability, aperture 3
Fluctuations in the radiation angle distribution are detected at the metal electrode 11 provided near the upper position of the .

Then, based on this detection result, the electron beam is deflected by the deflection coil 13 using the crossover image a position as a fulcrum. Therefore, this deflection control does not cause a new change in the crossover image position, and the aperture 3
The intensity distribution at is always kept constant, thereby effectively compensating for variations in the position of the electron beam. Thus, a stable electron beam can be obtained by independently compensating for variations in the intensity and position of the electron beam.

In this way, according to the present device, a stable electron beam can be obtained as described above.

Moreover, its configuration is very simple and its control is also easy. Therefore, even when a high-luminance, long-life LaB6 cathode electron gun is used in place of the conventional tungsten filament electron gun, problems arise due to the instability of the electron beam emitted from the LaB6 cathode electron gun. Never. Now, in the explanation so far, the deflection coils 13 and 16 that compensate for instability have been described as being single, but generally depending on the specifications of the device, for example, there is no space for storing the deflection coils at the aperture position. Or, the position of the crossover image may not be certain.

In such cases, by setting the deflection coefficient, that is, the deflection coil in two stages, and appropriately setting the ratio of the deflection control currents, the fulcrum of electron beam deflection can be equivalently set to the crossover image or aperture position. Can be set to .
That is, it is assumed that the crossover image position or the aperture position x exists in the middle of the deflection coils 21 and 22 which are divided into two parts as shown in FIG.

And the above position x is distance X1 from coil 21, coil 2
2, and each deflection coil 21, 2
2 are the deflection angles α1 and i2 for the drive currents 11 and i2, respectively.
Let α2 be given. However, if the deflection fulcrum of the electron beam deflected through the two-stage deflection coils 21 and 22 is equivalently set at the position X, the following equation should be satisfied. (x1+X2)Tanα1=X
By driving the deflection coils 21 and 22 at a current ratio that satisfies the condition (X1+X2)i1''.X2(11+I2), the desired purpose can be achieved.

Further, as shown in FIG. 3, when the crossover image position or the aperture position Y is located above the two-divided deflection coils 21 and 22, the following procedure may be performed. .

The distance from the above position Y to the coils 21 and 22 is Y
If l, y2, then the following equation should be satisfied in this case.
Y2tan(α1-α2)=(Y2-y1)Tanα1
Therefore, as in the case 7 shown in FIG. 2, y1(11-
12)′. The desired purpose can be achieved by setting the current ratio to satisfy the condition (Y2-y1)i1.

Note that even when the crossover image position or the aperture position is located below the deflection coils 21 and 22, it can be set in the same manner. Note that the present invention is not limited only to the above embodiments.

For example, the present invention can be applied not only to a variable dimension beam shaping device using a two-stage beam shaping aperture, but also to the stabilization of a fixed dimension shaped beam, and its effects can be exhibited. Furthermore, if the crossover image position of the electron beam is stable, the deflection control system consisting of the metal electrode 14 and the deflection coil 16 may also be omitted. Furthermore, an electrostatic deflection plate may be used for deflection control, and it does not matter whether it is electromagnetic deflection or electrostatic deflection.
Further, the positions of the deflection system and the electrodes are not particularly specified as long as the positional conditions that are the gist of the present invention are satisfied. In short, the present invention can be implemented with various modifications without departing from the gist thereof. As described in detail above, according to the present invention, a stable electron beam can always be obtained with a simple configuration and simple control, and it has various extraordinary advantages and
An effective electron beam device can be provided here.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an optical system showing an embodiment of the present invention;
FIGS. 2 and 3 are diagrams each showing the action of a two-stage deflector. 1... Electron gun, 3, 6... Aperture, 8... Objective lens, 9... Target, 11, 14... Metal Electrode, 12, 15...
... Deflection control device, 13, 16 ... Deflection coil, 21, 22 ... Deflection coil (two-stage configuration)
, A, b... Crossover image, C...
Aperture position, X, Y...Crossover image (
aperture) position.

Claims (1)

[Claims] 1. In an electron beam device in which an electron beam emitted from an electron gun is shaped through an aperture and then irradiated onto a target, an electrode for detecting a shift of the electron beam is disposed near the aperture position, An electron beam apparatus characterized in that a deflection system that deflects the electron beam according to a detection result by the electrode is disposed closer to the electron gun than the electrode and near a crossover image position of the electron beam. 2. The deflection system is configured to be divided into two parts in the axial direction of the electron beam, and determines a beam deflection control current ratio to equivalently deflect the electron beam using the crossover image position as a fulcrum. Electron beam device described in Section 1.