JPS60136141A - Charged particle radiation device - Google Patents

Abstract

PURPOSE:To simplify axial adjusting of a charged particle optical system and a charged particle source together with location of a movable diaphragm by providing the movable diaphragm with an electrode for detection of a charged particle beam. CONSTITUTION:Two kinds of electrodes for detecting a current of a charged particle beam 9 are provided on a movable diaphgram 5. When an electrode for location is properly provided on the movable diaphgram 5, the relation of relative positions of the pass position of the charged particle beam 9 and the movable diaphgram 5 proper, further an aperture can easily be known. Further, the electrode 41 for axial adjusting makes it easy to see the extent of distribution of the charged particles and whether a state of the charged particle beam 9 is symmetric with respect to the axis or not. Thereby, axial adjusting of a charged particle optical system and a charged particle source as well as location of the movable diaphragm can be simplified.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a charged particle irradiation device used for the purposes of processing, lithography, analysis, film forming surface improvement, etc. This invention relates to a charged particle irradiation device that facilitates the alignment of a charged particle optical system and a charged particle source and the position setting of a movable diaphragm by providing electrodes for the charged particle optical system and the charged particle source.

[Background of the invention]

Figure 1 shows an overview of the configuration of an example of a charged particle beam irradiation device equipped with a movable diaphragm, but this shows that it is difficult to position and set the anno-cha at the position where the charged particle beam passes. It has some problems, such as:

That is, in a charged particle irradiation device equipped with a movable aperture, a charged particle source 1 is arranged in a vacuum chamber 11, and electrons or ions are extracted from this charged particle source 1 by an extraction electrode 2, forming a round hole 5.

The charged particle beam 9 extracted in this way is first narrowed down by a fixed aperture 3, then focused by a lens 4, and then deflected by a deflector 6 and irradiated onto a target 7 placed on a table 8. This is what is meant to be done. By irradiating the target 7 with the charged particle beam 9, secondary particles such as secondary electrons emitted from the target 7 are detected and various analyzes are performed.
The target 7 itself is processed by irradiated charged particles. By the way, charged particle beam 9
When irradiating the Tadak 1.7, the beam current and beam diameter need to be adjusted to a specified value, and the equipment for these adjustments is inserted between the lens 4 and the deflector 6. This is a movable aperture 5. As will be described later, this movable aperture 5 has different diameters of several tens of μm.
Several 4-chats (holes) of about φ are bored, and if one of the 4'-chases is positioned at the position where the charged particle beam 90 passes from outside the vacuum using the xy moving mechanism 10, the hole can be opened. A charged particle beam having a beam current and a beam diameter corresponding to the Q-chamber can be obtained.

Figure 2 shows the movable diaphragm commonly used today and its XY
This figure shows a specific example of the Y movement mechanism.

As shown in the figure, the movable diaphragm 5 is provided with apertures (four in this example) in a row, and the movable diaphragm 5 itself can be moved back and forth and oscillated via a shaft 12. X
The YY movement mechanism is airtightly attached to the LX empty chamber via the flange 14, but the XY movement mechanism itself is attached to the shaft 1.
2. In addition to the flange 12, there is a perose 15, a slider 16,
Holder 17, spring 23, push spring 19, fulcrum member 13
, micrometers 18, 20, etc. The position of the movable diaphragm 50 in the front and back direction can be set depending on the micrometer, and the swing position can be set depending on the micrometer 18. In the end, the micrometer is,
20, any of the apertures formed on the movable diaphragm 5 can be positioned and set at the position through which the charged particle beam passes.

However, since the diameter of the hole through which the charged particle beam passes is generally small, on the order of several tens of micrometers, it is not easy to move the movable diaphragm so that the aperture is located at the passing position, and it takes a lot of time. The reality is that this is happening. Further, even if it were possible to position the aperture at the passing position, the reality is that it is still not easy to set the aperture at the optimum position. Setting the position to the optimal position can be done, for example, by detecting secondary electrons emitted from the target and
It is common practice to obtain a secondary electron image and adjust the aperture position while observing the secondary electron image. However, not only does it generally take a lot of time to adjust, but the time is also greatly influenced by individual differences. It has become something that Furthermore, when replacing the charged particle source or when the charged particle emission point changes over time due to the characteristics of the charged particle source itself, the axis of the charged particle source and the optical axis (the center of the charged particle optical system consisting of lens 4, etc.) It is necessary to align the two axes), but even in such cases, the reality is that alignment is performed while moving the position of the charged particle source and observing changes in the brightness of the secondary electron image. . However, when the axis alignment is performed in this manner, the same problem occurs as when setting the optimal position hair, 41-cha.

[Purpose of the invention]

Therefore, it is an object of the present invention to quickly and easily set the ano-cha on the movable aperture to the charged particle beam passing position in good condition, and to quickly and easily align the charged particle source and the optical axis. The object of the present invention is to provide a charged particle irradiation device that can be easily used.

[Summary of the invention]

For this purpose, the present invention provides two types of electrodes on the movable aperture for detecting the current of the charged particle beam. When positioning electrodes are appropriately installed on the movable aperture, the passage position of the charged particle beam and the movable aperture itself,
Furthermore, the relative positional relationship with the percher can be easily known, and depending on the axial alignment electrode, it is also possible to determine whether the current distribution of the charged particle beam spreads or whether the state of the charged particle beam is axially symmetric. It is easy to know.

[Embodiments of the invention]

The present invention will be explained below with reference to FIGS. 3 to 14.

First, we will explain the movable diaphragm that allows the aperture to be quickly and easily set to the charged particle beam passing position using FIGS. An electrode for positioning the beam passing position and an electrode for aligning the charged particle source with the optical axis are provided, but for convenience of explanation, the electrode for positioning will be explained first. As shown in K, strip-shaped electrodes 22 and 23 are arranged on both sides of the apertures/4'-chas that are bored in five rows of movable apertures in this embodiment.1!The poles 22 and 23 are as follows. For example, Mo plates with a thickness of 100 μm are used, and these are attached to the movable diaphragm 5 through a ceramic ring 26 with a thickness of 0.5 mm and screws while maintaining an insulating state.

FIG. 4 shows how the movable diaphragm 5 sets the aperture to the charged particle beam passing position. In this case, if the movable aperture 5 is inserted near the orbit of the charged particle beam 9 and is oscillated by the XY moving mechanism 10, the electrodes 22 electrically connected to the outside will move the charged particle beam 9. At the time of passing, the electrode 22
, 23, a current due to the charged particle beam 9 flows through them. This current is detected by the ammeter n via the lead wire 5 and is recorded by the recorder as two peaks, but if the second peak is detected, the movable diaphragm 5 is moved in the opposite direction. It is intended to bring it back. If the first peak is detected while returning in the opposite direction, the oscillation movement is stopped at that point, and as a result, the movable diaphragm 5 detects that the charged particle beam 9 exists between the electrodes 22 and 23. The location is determined by the state.

If the movable aperture 5 is then moved in the front-rear direction by the XY moving mechanism 10, the charged particle beam 9 will definitely pass through the position of each aperture, so the movable aperture 5
By detecting the presence or absence of current under the current, the charged particle beam can be passed through the desired percha. Previously, positioning was done solely by relying on experience, and it took nearly 10 minutes to set the position, but when setting the position as described above, it can be done in just one minute. be.

5 and 6 show a more preferable embodiment of the movable diaphragm shown in FIG. 3. First of all, according to the explanation shown in FIG.
It is arranged in the same way. When moving the movable diaphragm 5 in the front-back direction to pass the charged particle beam 9 through the apertures/4'-cha, if the current flowing through the electrode 4 arranged between the apertures/4'-cha is detected and recorded, the charged particle beam 9 is detected and recorded. It is easy to know in which aperture the beam 9 is located or in its vicinity.Next, referring to FIG. 6, in this embodiment an electrode I is provided around each aperture. A plurality of them (four in this example) are arranged. This gap between the electrodes not only allows us to know which aperture or its vicinity the charged particle beam 9 is located, but also allows us to set the aperture to the charged particle beam passage position of the aperture in a better condition.1. C. It is possible.

For example, assuming an inverted T case where a charged particle beam is applied to an aperture with the smallest diameter as shown in FIG.
It is clear that when the charged particle beam 9 is irradiated onto the four electrodes, there is a difference in the amount of charge incident between the four electrodes. Therefore, the current from between these electrodes is transferred to the lead wire 32.
If the current is detected by the ammeter 27 and the XY movement mechanism controller controls the XY movement mechanism 10 so that the currents are equal, the charged particle beam will be - It can be injected into tea in good condition. Therefore, until now the I of the secondary electron image
IJ 0) The position of Anno 4-cha was set depending on the flow etc., which took a lot of time, but it was automatically set.
Moreover, it becomes possible to quickly set the position.

FIG. 8 shows a structure of a movable diaphragm according to the present invention which is different from that shown in FIGS. 3(al and bl).

As shown in the figure, electrodes are arranged around each aperture. In this case, the electrode 34 is the electrode 22 described above.
, 23 functions, and it is also possible to know in which anomaly or its vicinity the charged particle beam is located. However, in order to provide the function of electrode n+, the length of the gap existing between the electrodes must be set appropriately short. The length needs to be set smaller than the charged particle beam diameter at the movable aperture position, but this is because when the movable aperture 5 is oscillated, the charged particle beam is detected by one of the electrodes 34. This is because it needs to be done. For example, when focusing an ion beam using a liquid metal ion source as a charged particle source, the magnification of the lens at the top of the movable aperture is approximately 1, so ions with a beam diameter similar to the aperture diameter of the fixed aperture can be focused. The beam is incident on the movable aperture, and if the aperture diameter of the fixed aperture is 500 μm, the length of the gap 41 needs to be set at least smaller than 500 μm. By the way, it is almost impossible to arrange the electrode joints with the length of the gap smaller than 500 μm depending on the method of insulating the Mo plate with a ceramic ring. For this reason, it is conceivable to form the electrode tone on a ceramic sheet by printing.It is also conceivable to configure the electrode 34 like the electrode 30.

Now, with reference to FIGS. 9 and 10, a movable diaphragm in which the diaphragm plate eye is used as a position setting electrode will be explained.

In the movable diaphragm according to the present invention to date, the position setting electrodes are all conductive plates with apertures, that is,
The aperture plate was constructed separately from the aperture plate, but in the ones shown in FIGS. 9 and 10, the aperture plate eye body also serves as a position setting electrode.

First, to explain what is shown in FIG. 9, the movable diaphragm in this embodiment has a rectangular diaphragm plate 35 attached to a holding member 36, and a slit-shaped opening 38 is formed in the upper part of the diaphragm plate 35. Furthermore, the conductor cover 37 is attached in a state where it is electrically insulated from the aperture plate 35. In this case, in order for the charged particle beam to be incident on either A or 4+-Char by the back and forth movement of the movable aperture itself while the beam current is being detected by the aperture plate 35, the width of the aperture plate 350 must be equal to the width of the aperture plate 35. It can be said that it is desirable to make the beam diameter twice or less the above beam diameter. For this purpose, it is sufficient to narrow the width of the aperture plate 35 itself, but it is generally difficult to reduce the width of the aperture plate 35. 5 is a diaphragm plate 35 to suppress scattering of the charged particle beam within the percha.
is constructed as a thin foil made of Mo or the like with a thickness of about 10 μm, and the narrower the width, the weaker the strength becomes. Therefore, in this embodiment, the width of the aperture plate is narrowed not by the aperture plate 35 but by the conductor cover 37. The width of the slit opening is 2 times the beam diameter.
It is good as long as it is formed less than double the size. For example, when the beam diameter on the aperture plate 35 is about 500 μm, the width of the slit-shaped opening is set to be 1000 μm or less.

Next, the device shown in FIG. 10 will be described. The only difference between this and the device shown in FIG. 10 is that the conductor cover 37 is divided into two parts. The slit existing between the conductor covers 39 and 40 is used instead of the slit-shaped opening described above, and with this configuration, the movable diaphragm can be constructed easily. In addition, the aperture plate 3
As for 5, a gap is provided between the a and 41-cha, thereby making it possible for each a/1-cha to independently detect the charged particle beam.

Now, using the above-mentioned position setting electrode, the aperture can be quickly and easily positioned at the charged particle beam passing position, but prior to positioning the aperture, it is generally necessary to Matching must be completed. This is because the position setting of the anno(-cha) is based on the premise that the spatial distribution of the beam current is axially symmetrical.

Charged particle source 1 as shown in Figure 11 (at, (bl)
When the alignment between the beam and the optical axis is complete or good, the spatial distribution of the beam current I also becomes axially symmetrical. However, if the charged particle source 1 and the original axis are misaligned as shown in Figure 12 (at, fbl), the spatial distribution of the beam current also causes astigmatism in the optical system, so axial symmetry cannot be achieved. Therefore, if the spatial distribution of the beam current is not axially symmetrical, it is necessary to make it axially symmetrical. It's an electrode.

For example, the alignment electrode is q#I as shown in FIG.
It is arranged on the aperture 5. In this embodiment, the alignment electrode 41 is combined with the positioning electrode shown in FIG. 6, and is shaped like a cross as a whole and is provided near the positioning electrode; however, it may be combined with any positioning electrode. Also, the overall shape and the individual electrode shapes are not necessarily limited to those shown in the drawings. The shape of each individual electrode may be circular, or the shape of the electrode may be arranged in the shape of a grid as a whole, but where each electrode is arranged depends on the beam diameter on the dynamic aperture. It is necessary to take this into consideration and determine it appropriately. For example, when the beam diameter is about 500 pm, the alignment electrode 4J has a 30 μm square shape.
They are arranged in a cross shape with 11 pieces in the vertical and horizontal directions at 20 pm intervals.

By the way, multiple alignment electrodes are arranged two-dimensionally to detect the two-dimensional spatial distribution of the beam current, and although their size is quite small, such electrodes can be formed by sputter deposition or plasma etching. .

FIG. 14 (al, (bl) shows the structure of the alignment electrode and its surroundings formed in this way.

According to this, the alignment electrode 41 made of Al is 5r02
It is formed in the well-shaped depression of the insulating layer 43, and 5iQ
An AI thin film 42 is formed on the outer surface of the second insulating layer 43 other than the side surfaces and the electrode forming portion. Al
The reason for forming a thin film is that if the insulating layer is exposed and charged in areas other than the electrode formation area, it will interfere with current measurement. A through hole 45 is also formed in the lower part of the electrode forming part of the insulating layer 43, and the alignment electrode 41 is formed in the lower part 5i (h) of the insulating layer 44.
While they can be drawn out to the outside via the I wiring layer 47, they are all formed on the S2 substrate 46 and are placed at the rear end of the aperture.

FIG. 15 shows an example of how to use the alignment electrode formed as described above. According to this, first, the alignment electrode group 41 is positioned directly under the charged particle beam using the strip-shaped electrodes 22 and 23, and then adjusted so that the center of the electrode group 41 and the center of the beam irradiation area 51 coincide. . At this point, the axis of the charged particle source is not yet aligned with the original axis, so it is in the X direction.

When the current detected by the ammeter n through the leader line 48 and selector 49 in both Y directions is displayed as a bar graph on the CRT on the controller, the graph is asymmetrical. Therefore, the position of the charged particle source is adjusted, the center of the group of electrodes 41 is again aligned with the center of the beam irradiation area 51, and the distribution of the beam current is confirmed on the CRT.

If the distribution is still asymmetrical, the position of the charged particle source is further adjusted, and this is repeated until the distribution becomes symmetrical in both the X and Y directions. This operation allows the axis of the charged particle source to be perfectly aligned with the optical axis. Then the electrode 30
is used to align the axis of the movable diaphragm 5 with the optical axis, and all axis alignment is completed. In this example, the axes of the charged particle source were aligned manually, but the alignment was completed in less than half the time it would take without such a method, and it was clearly shown on the CRT whether the axes were aligned or not. It was possible to determine.

In FIG. 16, the beam current is detected using the beam current detection mechanism on the movable aperture 5, the information is input to the controller blade through the ammeter 27, and the movable aperture XY moving mechanism 10 and the charged particle source This figure shows the configuration of a mechanism that moves the moving mechanism 52 to automatically align the axis of the charged particle source 1, the axis of the movable aperture 5, and the optical axis. The alignment process is the same as in the previous case, but the alignment can be done automatically and in a short time.

Although the charged particle irradiation device according to the present invention is equipped with two types of electrodes as described above, depending on the case, only one type of electrode is necessary and sufficient.

〔Effect of the invention〕

As explained above, the present invention includes a position setting electrode for setting the aperture to a charged particle beam passing position, and an alignment electrode for detecting the spread of the current distribution of the charged particle beam, on the movable aperture. It was designed to provide a. Therefore, the present invention has the advantage that positioning of the aperture on the movable aperture to the charged particle beam passing position and alignment of the charged particle source and the original axis can be performed quickly and easily.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of an example of a charged particle irradiation device equipped with a movable aperture, Figure 2 is a diagram showing a specific example of a general movable aperture and its XY movement mechanism, and Figure 3 is a diagram showing a specific example of a general movable aperture and its XY movement mechanism. (al,
(bl is a diagram showing a plane and a cross section of a movable aperture according to the present invention provided with a position setting electrode, and FIG. 5 and 6 are diagrams showing preferred configurations of the movable diaphragm shown in FIGS. 3 (al and lbl), respectively, and FIG. Figure 8, which is a diagram for explaining the setting method to the particle beam passing position, is similar to Figure 3 (at, (
Figures 9 and 10 showing the plane of the movable diaphragm according to the present invention, which are different from those shown in bl, respectively show the plane of the movable diaphragm according to the present invention in which the diaphragm plate itself is configured as a positioning electrode. Figures 11 (al), (bl) and Figure 12 (a). (bl is for explaining how the spatial distribution of the beam current changes depending on the alignment of the charged particle source and the original axis. FIG.
l, (bl is a diagram showing the configuration of an example of the alignment electrode, FIG. 15 is a diagram for explaining the method of aligning the charged particle source and the original axis using the alignment electrode, and FIG. 16 is 1 is a diagram showing the configuration when the axis alignment is automatically performed. 1... Charged particle source, 5... Movable aperture, 10...
Y movement mechanism, 22 , 23 , 29 , 30 , 34 ・
... (for aperture position setting) electrode, 35 ... (for aperture position setting) aperture plate, 37 , 39 , 40 ...
- Conductor cover, 41... (for alignment of charged particle source and optical axis) electrode. Representative Patent Attorney Tadashi Akimoto Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 Figure 9 Figure 10 Figure 11 (a) Figure 12 (a) Figure 13 Figure 14 (b) Figure 15 Figure 16

Claims (1)

[Claims] 1. Charged particles extracted from a charged particle source are accelerated and focused in a vacuum chamber, passed through an aperture provided on a movable aperture, and then deflected to a target. In a charged particle irradiation device designed to perform irradiation, a movable aperture consisting of a plurality of apertures with different diameters drilled in a straight line is equipped with a positioning electrode for setting the aperture to a position through which the charged particle beam passes. A charged particle irradiation device characterized in that it is provided with an axial alignment electrode for detecting the spread of a DC distribution of a charged particle beam. 2. The charged particle irradiation device according to claim 1, wherein a position setting electrode is provided separately from the aperture plate as the aperture forming portion. 3. The charged particle irradiation device according to claim 1, wherein the aperture plate body serving as the aperture forming portion is used as a position setting electrode. 4. On both sides of the aperture formed by multiple linear holes,
The charged particle irradiation device according to claim 2, wherein a strip-shaped electrode is provided along the aperture as a position setting electrode. 5. The charged particle according to claim 2, wherein a strip-shaped electrode having a window formed in a portion corresponding to the aperture is provided as a positioning electrode above a plurality of linear apertures. The charged particle irradiation device according to claim 3, wherein conductor covers are provided on both sides of the aperture in the diaphragm plate of the irradiation device O6 and along the aperture. 7. Place the a/f-cha on the top of the aperture plate.
- The charged particle irradiation device according to claim 3, further comprising a conductor cover in which a slit-shaped window is formed along the conductor cover. 8. The charged particle irradiation device according to claim 4, wherein an independent small electrode is provided near the aperture. 9. The charged particle irradiation device according to claim 5, wherein a gap is provided between the electrode portions existing between adjacent anofa. 10. The charged particle irradiation device according to claim 6 or 7, wherein the interval between the conductor covers or the slit width of the slit-like window is not more than twice the diameter of the charged particle beam on the conductor cover. 11. The charged particle irradiation device according to claim 8, wherein the small electrode is provided between adjacent annoyarchs. 12. The charged particle irradiation device according to claim 8, wherein at least two or more small electrodes are provided around each of the armatures. 13. The charged particle irradiation device according to claim 9, wherein the electrode portions separated by the gaps are provided with radial gaps around the aperture. 14. The charged particle irradiation device according to claim 3, 6, 7, or 10, wherein a gap is provided between the intermediate surfaces of adjacent apertures in the aperture plate. 15. The charged particle irradiation device according to claim 4, 8, 1] or 12, wherein the strip-shaped electrodes are electrically connected to each other. 16. On the movable aperture region excluding the aperture or aperture plate and the positioning electrode, there are at least five two-dimensional microelectrodes with a size that is equal to or less than V3 of the charged particle beam diameter on the movable aperture. A charged particle irradiation device according to any one of claims 1 to 15. 17. The charged particle irradiation device according to claim 16, wherein the microelectrodes are provided in a cross shape within a range less than twice the diameter of the charged particle beam on the movable aperture. 18. The charged particle irradiation device according to claim 16, wherein the microelectrode is provided on a base within a range of twice or less the diameter of the charged particle beam on the movable aperture.