JPS5856946B2 - 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, electron beam devices using high-intensity and long-life LaB6 electron guns have been widely put into practical use.

However, the electron beam emitted from the LaB6 electron gun generally has a problem in that the crossover position tends to fluctuate and, moreover, the radiation distribution angle (intensity distribution) tends to fluctuate.

For this reason, the intensity of the electron beam that is shaped through the aperture, focused through the electron lens, and irradiated onto the target is unstable, and the irradiation position is 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 has been a problem in that stably controlling the electron beam intensity causes the beam position to fluctuate, and conversely, stably controlling the beam position causes the intensity to fluctuate.

For this reason, it has always been difficult for JF to effectively use the L8B6 electron gun, which has the advantages described above.

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 position of the electron beam without destabilizing the intensity of the electron beam. The goal is to realize and provide the following.

That is, it is an object of the present invention to provide an electron beam apparatus capable of correcting crossover positional fluctuations in a Kohler-irradiated electron beam without causing beam positional fluctuations.

An embodiment of the present invention will be described below 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 comprising a 6La86 cathode is connected to a lossover a through a condenser lens 2, and then is irradiated onto a first beam shaping aperture 3 according to its beam opening angle.

The image of this aperture 3 is transmitted to the first and second projection lenses 4,
5 onto a second beam shaping aperture 6 .

By controlling the direction of the electron beam projected from the first beam shaping aperture 3 to the second beam shaping aperture 6, the electron beam is shaped in variable dimensions.

Thus, the image of the shaped electron beam is reduced and projected onto the target 9 via the reduction lens γ and further via 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.
2 is entered.

This deflection side device 12 is located at the crossover position a.
The in-plane coil 13 provided in the vicinity of is driven once to deflect the electron beam using the crossover position a as a fulcrum.

Further, a metal electrode 14 is coaxially disposed near the top of the objective lens 8, that is, near a crossover image focused at the center of the objective lens 8.

This metal electrode 14 detects the positional shift of the crossover image, and the detected information is transmitted to (2) the opposite side device 15.
has been entered.

This (2) angle control device 15 includes an in-plane coil 1 disposed coaxially with the second beam shaping aperture 6.
6 to deflect the electron beam using the aperture position C as a fulcrum.

If we analyze the unstable factors of the electron beam focused on the target 9 using the apparatus configured as described above, that is, the optical system, it can be classified into two types as follows.

One is by changing the position of crossover a,
This is because the magnification crossover position formed on the objective lens 8 changes.

As a result, the amount of the electron beam passing through the aperture 8a of the objective lens 8 fluctuates, and the beam intensity fluctuates, that is, becomes unstable.

On the other hand, the radiation angle distribution of the electron beam emitted from the electron gun 1 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 Kohler-irradiated 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, to prevent the positional fluctuation of the crossover image caused by the fluctuation of the crossover position of the electron beam. Detected.

Then, the forward coil 16 provided at the position of the aperture 6 is driven to deflect the electron beam, thereby compensating for the variation in the crossover position.

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.

That is, by independently compensating for variations in the crossover position, it is possible to obtain an electron beam that is always stable and has an intensity of t.

On the other hand, regarding the latter instability, fluctuations in the radiation angle distribution have been detected at the metal electrode 11 provided near the upper part of the aperture 3.

Based on this detection result, (S+
is carried out.

Therefore, no new fluctuations in the lossover position are caused by this side, and the intensity distribution at the aperture 3 is always kept constant, thereby effectively compensating for the fluctuation 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-brightness, long-life La86 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 La86 cathode electron gun. There is no.

Now, in the explanation so far, the forward coils 13 and 16 that compensate for instability have been described as being single, but in general, depending on the specifications of the device, for example, there is no space for storing the forward coils at the aperture position. Or, the crossover position may not be certain.

In such a case, the forward fulcrum of the electron beam can be crossed over in an iso-picture manner by configuring the inter-plane system, that is, configuring the forward coil in two stages, and setting the ratio of the in-plane inversion current appropriately. , or can be set at the aperture position.

That is, it is now configured into two parts as shown in Figure 2 (2)
It is assumed that the crossover point or aperture position X for the opposite coil 2L22 is located in the middle of the coils 21 and 22.

The above position X is at a distance of X1 from the coil 21 and the coil 2
2, and each face-to-face coil is 21°2.
2 is the turning angle α0 for the drive type 1fUf1yf2, respectively. Let α2 be given.

However, if the in-plane fulcrum of the electron beam deflected through the two-stage (to) direction coil 2L22 is isographically set at the above position X, then if the following equation is satisfied: good.

The deflection coil 21°22 is set to 1 at a current ratio that satisfies the condition
By driving, the intended purpose is achieved.

Further, as shown in FIG. 3, in the case where the crossover or aperture position Y is located above the inter-plane coil 21, 22 which is configured to be divided into two parts, the following procedure may be performed.

The distance from the above position Y to coil 21 and 22 is y respectively.
Assuming that l and y2, in this case, the following equation should be satisfied.

y2tan(α1~α2)=y2yl)tan
Therefore, the desired purpose can be achieved by setting the current ratio to satisfy the condition 71(jt-12)';(3'2-yt)jt as in the case shown in FIG. 2.

Note that the crossover and master can be set in the same manner even when the aperture position is located below the deflection coil 2L22.

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 radiation angle distribution of the electron beam is stable, the planar system consisting of the metal electrode 11 and the deflection coil 13 may be omitted.

Furthermore, an electrostatic forward plate may be used in the forward system, and electromagnetic (b)
Regardless of direction or electrostatic deflection.

Further, the positions of the intrasinus system and the electrodes are not individually 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 detailed above, according to the present invention, an electron beam device is provided which can always obtain a stable electron beam with a simple configuration and simple control, and which exhibits various extraordinary advantages and effects. can be provided.

[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 operation of the two-stage end system. 1... Electron gun, 3, 6... Aperture, 8... Objective lens, 9... Target, ICl3... Metal electrode, 12.15... (2) Surface control device, 13, 16・
... Forward coil, 2L22... Deflection coil (two-stage configuration), a... Crossover position, b... Crossover image position, C... Aperture position, X, Y... Crossover (aperture) position.

Claims (1)

[Scope of Claims] 1. An electron beam device that shapes an electron beam emitted from an electron gun through an aperture and then irradiates it to a target, so that the electron beam is shifted in the vicinity of the crossover image position of the electron beam. An electron beam apparatus characterized in that a detection electrode is arranged, and a deflection system for deflecting the electron beam according to the detection result by the electrode is arranged near the aperture position. 2. The deflection system is configured to be divided into two parts in the axial direction of the electron beam, and is configured to deflect the electron beam in an isometric manner with the aperture position as a fulcrum by determining a beam plane control current ratio. The electron beam device according to item 1.