JPH0821351B2 - Electronic beam alignment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to an electron beam alignment method for an electron beam apparatus, in which a deflection voltage such as a triangular wave is input to one of opposing electrodes of a deflector, and an electron is reflected from the other by hitting an aperture. Is detected as an absorption current, and the electron beam is controlled so that the electron beam passes through the center position of the deflector.

As a result, the electron beam can be aligned with the geometric center axis of the deflector in a short time, the processing efficiency of the electron beam device can be improved, and the life of the electron optical system component can be extended.

[Industrial applications]

The present invention relates to an electron beam alignment method, and more particularly to a method for aligning an electron beam with a central axis of a deflector in a short time.

[Conventional technology]

FIG. 4 is a diagram illustrating an electron beam alignment method according to a conventional example.

In the figure, the electron beam 15 emitted from the electron gun 2 in the electron beam column 1 includes an anode 9, an alignment coil 3, an aperture 10, a sub-deflector 5, an aperture 11, a main deflector 4,
The light enters the sample chamber 13 through the electron lens 6, the scan coil 7, the electron lens 8 and the aperture 12, and reaches the Faraday gauge 16 provided on the stage 14.

Next, the amount of incident electrons reaching the Faraday gauge 16 is detected by the minute ammeter 17. Then, the alignment coil 3 is adjusted so that the amount of incident electrons is maximized, and the center of the electron is aligned with the geometrical central axes of the main and sub deflectors.

[Problems to be solved by the invention]

By the way, according to the electron beam alignment method of the conventional example, if the electron beam lens barrel is mechanically assembled with high accuracy, the anode 9, the alignment coil 3, the aperture
Up to 10 and the sub-deflector 5, the alignment coil 3 can be adjusted to pass an electron beam.

However, it may not be possible to pass the electron beam through the aperture 11 for the main deflector first. Alternatively, part of the beam may hit the aperture 11. That is, by adjusting the alignment of the electron beam 15 for a long time, contamination is gradually attached to the aperture and optical system parts, and due to the charge-up phenomenon caused by this, the electron beam 15 does not enter the aperture portion of the aperture. This causes a state of being largely deviated.

Therefore, the electron beam 15 does not reach the stage 14 of the sample chamber 13 even if the alignment coil 3 is adjusted for a long time.

The present invention was created in view of the problems of the conventional example, and provides an electron beam alignment method capable of aligning the electron beam with the geometric center axes of the main and sub deflectors in a short time. To aim.

[Means for solving problems]

The present invention, as shown in FIGS.
A triangular wave or sawtooth wave deflection voltage is input to one of the opposing electrodes of the deflector (25). Of the electron beam from the electron gun (22) deflected by this deflection voltage, the electron reflected by the aperture (28) located below the deflector (25) is detected as the absorption current of the counter electrode. Further, the absorption current is monitored, the passing position of the electron beam with respect to the aperture (28) is detected, and the electron beam is controlled so as to pass through the center of the aperture based on the detection result.

[Action]

According to the present invention, the electron beam from the electron gun (22) is deflected by the deflection voltage and reflected by the aperture (28) located under the deflector (25), and the reflected electrons are absorbed by the counter electrode. Detected as.

At this time, since the amount of absorption current corresponds to the amount of displacement of the electron beam, it is possible to detect the displacement of passage position of the electron beam with respect to the aperture (28) by monitoring this absorption current.

Therefore, the electron beam can be aligned with the geometrical center axes of the main and sub deflectors in a short time without hitting the edge of the aperture or the optical system components.

Further, it is possible to reduce the contamination attached to the aperture and the optical system component, which makes it possible to prolong the life of the electron and the optical system component.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining an alignment method of an electron beam apparatus according to a first embodiment of the present invention, and FIG. 1 (a) is an enlarged view of a sub-deflector portion in an electron beam lens barrel.

In the figure, an electron gun provided in the electron beam column 21.
The electron beam 29 emitted from 22 includes an anode 26, an alignment coil 23, an aperture 27 for a sub-deflector 25, and a sub-deflector.
It passes through 25 and reaches the aperture 28 for the main deflector 24 by adjusting the alignment coil 23. The alignment coil 23 is provided with an electron beam 29 which has a geometrical optical axis XY
An X-axis adjuster 23a and a Y-axis adjuster 23b for aligning the axes are provided.

Next, the deflection voltage ± Vd of triangular wave or sawtooth wave is input to the terminal 31 of the sub deflector 25. In addition, the electron beam 29
The amplitude of Vd is adjusted so that the deflection is larger than the aperture of 28. Also, connect the amplifier 33 to the terminal 32 and the oscilloscope for monitoring.
Connect the detection circuit formed by 34 and. The electron beam 29 deflected by the deflection voltage ± Vd larger than the aperture diameter of the aperture 28 is reflected by the aperture 28 and reflected electron
30 is absorbed by the counter electrode of the sub deflector 25. Then, the absorption current is amplified by the amplifier 33, and Vi is input to the oscilloscope. In the present invention, the state of the electron beam 29 incident on the aperture 28 can be detected by the oscilloscope 34, but the absorption current can also be detected by a minute ammeter ((a) in the same figure).

Next, FIG. 9B is a block diagram for explaining an electron beam alignment method.

In the figure, an electron beam 29 emitted from an electron gun 22 passes through an alignment coil 23, enters a sub-deflector 25, and is deflected by a triangular wave voltage 35. Also the aperture 28
The state of the electron beam 29 incident on is detected by the detection circuit 37. By adjusting the alignment coil 23 by the adjusting means 36, the central portion of the electron beam 29 and the geometrical central axes of the main and sub deflectors can be matched.

The adjusting means 36 can manually adjust the X-axis adjuster 23a and the Y-axis adjuster 23b provided in the alignment coil 23 to adjust the D / A.
It is also possible to perform automatic control using the conversion circuit 39 and the control circuit 40.

Next, FIG. 7C is a diagram for explaining the relationship between the voltage waveform of the oscilloscope 34 used in the first embodiment of the present invention and the electron beam 29 alignment method.

In the figure, the central portion 42 of the electron beam 29 is shown to be located on the Y axis of the geometrical coordinates of the main and sub deflectors (the origin of the XY axes is the central axis).

The voltage waveform of the oscilloscope 34 corresponding to this relationship is
The deflection voltage ± Vd can be seen on the horizontal axis and the output voltage Vi of the amplifier can be seen on the vertical axis.

That is, the voltage waveform is P-Q-R-S-T-U-
It is a curve shown by V. In addition, between R-S-T, the part where the electron beam 29 is incident on the aperture portion 41 of the aperture 28 is shown, and between P-Q and U-V, the part where the electron beam 29 is reflected by the aperture 28 is shown.

Therefore, as shown in the figure, by equalizing the voltage between R and S and between S and T, the central portion 42 of the electron beam 29 is moved to Y.
It will be aligned with the axis. Then R-S-T (Q
By maximizing the voltage between −U), the central axis 42 of the electron beam 29 is aligned with the origin of the XY axis along the Y axis.

Next, FIG. 2 is a diagram for explaining a method of specifically adjusting the alignment coil 23 from the voltage waveform example of the oscilloscope 34 to align the electron beam 29.

In FIG. 3A, a circle shown by a broken line for convenience is a virtual aperture diameter 43, and X ′, Y ′ axes are virtual coordinates (X ′, Y ′) of the electron beam 29 of the diameter portion 43.

First, as shown in the figure, since the voltage waveforms R-S and S-T are equal to each other, the central portion 42 of the electron beam has the Y-axis (Y =
Y '). In this case, the Y of the alignment coil 23
By adjusting the axis adjuster 23b and increasing the voltage between Q and U, the central portion 42 of the electron beam 29 can be aligned with the geometrical central axis 38.

In addition, in the same figure (b), the voltage between Q and U is large,
Since the voltages across RS and ST are not equal, the central portion 42 is on the X axis (X = X '). In this case, the X-axis adjuster
The electron beam 29 can be aligned by similarly adjusting 23a.

Next, in the same figure (c), the voltage between Q and U is also small and RS, S
This is the case when the voltages between −T are not equal. That is, the central portion 42 is not located on the X axis or the Y axis (X ≠
X ', Y ≠ Y'). In this case, either one of the X and Y axis adjusters 23a and 23b is adjusted so that the electron beam 29 is first aligned on the X axis or the Y axis. Then, the adjustment is performed as shown in FIG. In this way, the electron beam 29 can be similarly aligned.

It should be noted that FIG. 7D shows the case where the central portion 42 of the electron beam 29 and the geometrical central axis 38 of the main and sub deflectors coincide with each other.
The voltage waveform of the oscilloscope 34 is shown.

FIG. 3 is a diagram for explaining an electron beam alignment method according to the second embodiment of the present invention.

It should be noted that FIG. 9A is a diagram showing the configuration of the electron beam apparatus, and is different from the first embodiment in that the alignment coil 23
That is, the aperture 44 and the electron lens 45 are arranged between the sub-deflector 25 and the sub-deflector 25. Reference numeral 44a is an adjuster that changes the position of the aperture 44 and the size of its opening.

FIG. 3B is a block diagram showing an electron beam alignment method. The difference from the first embodiment is that the electron beam emitted from the electron gun 22 is monitored as the absorption current of the counter electrode of the deflector 25, the passing position of the electron beam with respect to the aperture 28 is detected, and the aperture 44 is adjusted. Means 36,
For example, it differs in that the aperture adjuster 44a is changed to control the electron beam.

Further, an electron beam alignment method using both the adjustment of the alignment coil 23 according to the first embodiment and the adjustment of the aperture 44 according to the second embodiment is also possible.

An example of the voltage waveform of the oscilloscope 34 and an example of adjusting the aperture 44 according to the second embodiment will be omitted.

In this way, the electron beam 29 can be aligned by adjusting the X and Y axis adjusters 23a and 23b of the alignment coil 23 while observing the voltage waveform Vi of the oscilloscope 34.

Therefore, the central portion 42 of the electron beam 29 can be aligned with the geometrical central axes 38 of the main and sub deflectors in a short time.

Since the adjustment time of the alignment coil 23 can be shortened, contamination can be reduced. This makes it possible to extend the life of the optical system components such as the aperture 28.

〔The invention's effect〕

As described above, according to the present invention, it is possible to improve the alignment accuracy as compared with the conventional electron beam alignment method.

This makes it possible to improve the processing efficiency of the electron beam apparatus.

Further, according to the present invention, the service life of the electronic optical system parts and the like can be lengthened, so that maintenance merit can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an electron beam alignment method according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining the relationship between an oscilloscope voltage waveform example and an electron beam alignment method according to the embodiment of the present invention. FIG. 3 is a diagram for explaining the relationship between the voltage waveform example of the oscilloscope according to the second embodiment of the present invention and the electron beam alignment method, and FIG. 4 is a diagram for explaining the electron beam alignment method according to the conventional example. is there. (Explanation of symbols) 1,21 …… electron beam lens barrel, 2,22 …… electron gun, 3,23 …… alignment coil, 23a …… X axis adjuster, 23b …… Y axis adjuster, 4, 24 ...... Main deflector, 5,25 …… Sub deflector, 6,8,45…
… Electronic lens, 7… scan coil, 9,10,11,12,26,
27,28,44 …… Aperture, 9,26 …… Anode, 13 …… Sample chamber, 14 …… Stage, 15,29 …… Electron beam, 16 ……
Faraday gauge, 17 ... Micro ammeter, 30 ... Reflection electron, 31 ... Sub-deflector terminal, 32 ... Sub-deflector terminal, 33
...... Amplifier, 34 …… Oscilloscope, 35 …… Triangular wave voltage, 36 …… Adjustment means, 37 …… Detection circuit, 38 …… Main and geometrical axes of the sub-deflector, 39 …… D / A conversion circuit, 40 ... Control circuit, 41 ... Aperture aperture, 42 ... Electron beam center, 43 ... Virtual aperture aperture, 44a ... Aperture adjuster S, ± Vd ... Deflection voltage, Vi ... Output voltage of amplifier, X, Y ... X-axis and Y-axis of geometrical coordinates of main and sub-deflectors, X ', Y' ... X'-axis and Y'-axis of virtual electron beam coordinates.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Okubo 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Katsuhiko Doto 1015, Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture Fujitsu Limited Within

Claims (2)

[Claims] 1. An electron beam lens barrel (21) having at least an electron gun (22), an alignment coil (23), a deflector (25),
In an electron beam alignment method for an electron beam device in which apertures (28) are sequentially arranged from above, a triangular wave or sawtooth wave deflection voltage is input to one of the opposing electrodes of the deflector (25) and the deflection voltage is deflected by the deflection voltage. Of the electron beam from the electron gun (22), the deflector (25)
The electrons reflected by the aperture (28) located on the lower side are detected as the absorption current of the counter electrode, the absorption current is monitored, and the passing position of the electron beam with respect to the aperture (28) is detected, and the detection is performed. An electron beam alignment method characterized in that the electron beam is controlled so as to pass through the center of the aperture (28) based on the result. 2. The alignment coil (23) is adjusted based on a detection result of an electron beam passage position with respect to the aperture (28) by an absorption current monitor of an opposing electrode of the deflector (25), The electron beam alignment method according to claim 1, wherein the electron beam is controlled.