JPS63173325A - Electrostatic controller for charged beam - Google Patents

Abstract

PURPOSE:To prevent the effect of disturbance noises, and to simplify structure while precisely controlling charged beams with high accuracy by constituting all or one part of electrode supports of a semiconductor while installing an electrode for control outside the electrode supports centering around charged beams. CONSTITUTION:Electrode supports 1 are made of a semiconductor material such as SiC, and a volume resistance value thereof is approximately 10<6>OMEGAcm. The grounding resistance R1 of deflecting electrodes 2 generated by the electrode supports 1 made of SiC is approximately 10<6>OMEGAcm. When R1 takes a resistance value of approximately 10<6>, currents flowing into the deflecting electrodes 2 from a control power 9 is approximately 10<-4>A, and the control power 9 is hardly burdened. The effect of disturbance noises through leads 5 is made remarkably smaller than conventional devices by large lowering from high resistance close to the insulation of the grounding resistance R1, thus also improving the effect of resistors 5 affixed to the leads 5 markedly. Even when charged particles collide with the surfaces of the electrode supports 1, no charge-up is generated because the electrode supports 1 consist of a semiconductor. Accordingly, extremely accurate beam control is enabled.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention is a method of deflecting the beam or changing the beam diameter or beam cross-sectional shape using an electric field in various devices that perform microfabrication, elemental analysis, etc. using a charged beam. This invention relates to an improvement of an electrostatic controller for a charged beam, which is used to control the charged beam by changing the .

(Prior art and its problems) In a conventional electrostatic deflector for a charged beam (hereinafter, the electrostatic controller will be explained as a representative electrostatic deflector), its main part is a conductive deflection electrode. (For example, copper.

stainless steel, etc.) and an insulating electrode support that supports it (
For example, by applying a deflection voltage to the conductive deflection electrode, an electric field is formed and the charged beam is deflected.

For example, a front sectional view of a conventional electrostatic deflector is shown in Fig. 4A.
As shown in FIG. 4B, a cross-sectional plan view, a copper deflection electrode 2 is hermetically brazed to an insulating electrode support 1 made of alumina (Al2O2) or glass (S102).
Furthermore, a configuration is adopted in which the electrode support 1 is hermetically brazed and fixed to a grounded stainless steel frame 4.

The deflection electrode 2 thus constructed is arranged in one direction in both the X and Y axes.
The charged beam 3 is electrostatically deflected in both the X and Y directions by the deflection voltage applied thereto. The lead wire 5 to the deflection electrode 2 is connected to the frame 4
hole 40 made in the electrode support 1 and hole 10 made in the electrode support 1
0 and is soldered to the back surface of the polarizing electrode 2.

FIG. 4C shows an equivalent circuit for applying a voltage to one of the deflection electrodes 2. A deflection voltage is applied to the deflection electrode 2 from the control power supply 9 via the lead wire 5, but since the volume resistivity of the material of the electrode support 1 is extremely high (<1012 to 1014 Ωcm), Its resistance value usually shows a high grounding resistance value on the order of 1012 to 1014 Ω, and therefore, the equivalent resistance R1 of the electrode support 1 inserted between the grounded frame 4 and the deflection electrode 20 is a high resistance close to insulation. .

Now, the charged beam 3 is deflected using the electrostatic deflector with the above configuration, and the beam is irradiated onto an arbitrary position on the sample (not shown) to perform fine processing and analysis. Irradiation requires extremely high positional accuracy. For example, in an exposure device, for a deflection width of about 10 m In, 0.1
Accuracy below μrn, that is, high accuracy of about 10 −5 is required.

Therefore, the permissible value for variation in the voltage value applied to the deflection electrode 2 is extremely small and strict, and disturbance noise and other problems must be dealt with seriously.

The configuration of the conventional electrostatic deflector described above causes the following problems.

One of them is that the lead wire 5 to the electrostatic deflector easily picks up noise from the outside world, and the disturbance noise voltage that enters from the lead wire is superimposed on the deflection voltage, which causes damage to the charged beam. 3 is irregular vibration or agitation.

Another problem is that a part of the charged beam 3 is scattered and attached to the surface 11 of the electrode support 1 (charge-up), and since the scattering of the charged beam cannot be completely eliminated, The potential of the surface 11 of the support varies greatly due to the attachment and detachment of charged particles, which distorts the deflection voltage of the charged beam 3, causing unexpected fluctuations in deflection and preventing the convergence of the charged beam 3. was occurring.

Conventional countermeasures against these problems include the following.

That is, for the former, the lead wire 5 should be strictly shielded (
51) At the same time, a measure was taken to add an appropriate resistor R5 near the deflection electrode 20, also as a measure to protect the power supply during discharge. However, the results have not been very successful.

For the latter, measures were taken to prevent the surface of the electrode support from being exposed, such as by covering the electrode support 1 with a portion 21 of the deflection electrode, as shown in FIG. 5A. However, after implementing this, it became clear that this measure was insufficient for large swords in cases where a high degree of deflection accuracy was required using a small device.

In general, electrostatic deflectors are small, finished and assembled with high precision, and as shown in Figure 5B, they are configured with eight or more poles in order to improve deflection accuracy, and they are also constructed with eight or more poles in the axial direction. They are often stacked in several layers, making it very time-consuming and expensive to process. Fifth
The measures shown in Figure A were actually extremely complicated and difficult to implement.

As a precaution, FIG. 5C shows a method of distributing the voltages applied to each deflection electrode in FIG. 5B. X.

The deflection voltage in the Y-axis direction ±Vx, ±Vy is the resistance l
The voltage is applied to the nodes on all four sides of the resistor network made by the above, and the voltages at the other nodes are applied to the deflection electrode 2.

Furthermore, the following two issues can be raised. That is, one is that the surface potential of a conductive electrode is constant.

This means that it is not possible to create any desired electric field strength distribution along the surface. (
If this were to be achieved, the only way would be to line up a large number of small electrodes and apply an appropriate voltage to each of them, but as above, this process is virtually impossible.

) Another problem is that the structure of the electrostatic deflector is complicated, and it is difficult to attach the electrodes accurately.

There was such a thing.

(Objective of the Invention) The present invention solves the above problems, is not easily affected by disturbance noise, does not cause fluctuations in potential that would hinder beam convergence, and has a simple structure. The object of the present invention is to provide an electrostatic controller for charged beams that can control charged beams accurately and with high precision.

(Structure of the Invention) The present invention provides an electrostatic controller composed of a control electrode and an electrode support, in which all or part of the electrode support is made of a semiconductor, and a charged beam is centered on the electrostatic controller. An electrostatic controller for a charged beam, characterized in that the control electrode is installed outside the electrode support.

(Embodiment) FIG. 1A is a front sectional view of an electrostatic deflector according to a first embodiment of the present invention. Components corresponding to those in FIGS. 4A and 4B are given the same reference numerals and their explanations will be omitted.

The electrode support 1 is made of a semiconductor material such as SiC,
Its volume resistance value is about 106 Ωcm.

An electric field generated by applying a deflection voltage to the deflection electrode 2 acts on the charged beam 3 through the electrode support 1 . (
In detail, a current flows from the deflection electrode 2 to the grounded frame 4 through the electrode support 1, and the surface of the electrode support 1 becomes at a potential intermediate between the potential of the deflection electrode 2 and the ground potential. This potential generates an electric field in the central space, and the charged beam 3 is deflected. ) When the electrostatic deflector for a charged beam has the above configuration, the ground resistance R1 of the deflection electrode 2 shown in FIG. . If R1 has a resistance value of about 106, the current flowing from the control power source to the deflection electrode will be about 10-'A diameter, and will hardly place a burden on the control power source 6.

By significantly reducing the grounding resistance R1 from a high resistance close to insulation to about 106 Ω, the influence of disturbance noise passing through the lead wire 5 is significantly reduced compared to the past, and the influence of disturbance noise passing through the lead wire 5 is significantly reduced. The effectiveness of resistor R5 is also significantly increased.

Furthermore, even if charged particles collide with the surface of the electrode support 1,
Since the electrode support 1 is made of a semiconductor, charge-up does not occur at all. Therefore, very accurate beam control is possible.

However, the conditions that make this effect possible are as follows.

First, in order to generate a desired electric field at the position of the charged beam 3, the resistance value of the electrode support 1 must be adjusted to a designed potential by a current flowing from a deflection power source (not shown) to the deflection electrode 2. It must have enough value to hold it.

The realistic value for potential is about 102■, and that for current is 10
-'A diameter, so its resistance value needs to be 106Ω or more. If the electrode support 1 has a uniform resistance value and has dimensions of a cross-sectional area of 10 m2 and a length of Icm, its volume resistivity will be 106Ω11cm. Practically, it can be determined that the volume resistivity required to generate an electric field is 102 ΩCm or more, assuming that changes of about two orders of magnitude electrically and two orders of magnitude in dimensions are acceptable.

Next, in order to prevent the influence of charge accumulation (charge-up), even if a small amount of current in a part of the charged beam 3 collides with the electrode support 1, the amount of current will not affect the charged beam. The resistance value must be low so that no significant voltage is generated. As a realistic value, the collision current is 1O-6A
, Since the voltage that does not affect the beam is estimated to be 10°, the resistance value needs to be 106Ω or less. Similarly to the above, if electrical and dimensional tolerances are applied to this, the volume resistivity must be 1010 Ωcm or less.

From the above two conditions, the electrode support as a whole has approximately 1
It is necessary to have a volume resistivity of about 02 to 1012 Ωam.

FIG. 1B is a front sectional view of an electrostatic deflector according to a second embodiment of the present invention.

In this embodiment, the deflection electrode 2 is a simple electrically conductive film 2' attached to an electrode support 1.

The method of manufacturing this conductive film 2' includes a method of applying a metal film to the electrode support 1 by a metallization method, or, for example,
When the SiC electrode support 1 is made by firing, the electrode support 1
There are methods such as using the conductive deposited layer that appears on the surface as an electrode as it is, and furthermore, bending the wiring cable and laying it flat.

Since the electrode support 1, which is a semiconductor, has the function of trying to make the electric field uniform by itself through the movement of electric charges, the conditions regarding the accuracy of the mounting of the deflection electrode 2 of the present invention are considerably relaxed. . This is a side effect of the present invention.

FIG. 2A (front sectional view) and FIG. 2B (plane sectional view) are diagrams of an electrostatic deflector according to a third embodiment of the present invention.

In this embodiment, first, the frame 4 is eliminated, and the electrode support 1 itself serves as the frame. conventionally,
In the electrostatic deflector, a conductive tube called a drift tube is installed, or a grounded frame 4 is installed to completely surround the charged beam. However, in the present invention, since the electrode support 1 is made of a semiconductor, it is possible to make it function as a drift tube, and therefore the structure can be greatly simplified.

Electrostatic deflectors usually use 8-pole (see Figure 2B) or 16-pole deflection electrodes in one deflector (multipole deflection), and further stack these deflectors in two stages in the axial direction ( Second
This simplification of the structure is of great significance, as it employs a double deflection method in which the deflection of the charged beam is reversed (see Figure A). Since there is no joint between the electrode support 2 and the frame 4, there is no need for any special sealing technology, and another great advantage is that the electrode support itself can serve as a vacuum barrier.

Furthermore, the accuracy of the position of the deflection electrode 2 is uniquely determined by its mechanical processing accuracy, and since most of the machining is performed on the outer diameter side, high precision can be easily achieved. The electrode support 1 can also be expected to have a uniform effect on electric field distribution.

FIG. 2C is a sectional plan view of a fourth embodiment of the present invention.

In FIG. 2B of the above embodiment, a notch (horizontal notch 7) is inserted between the electrodes in order to make the distribution of the electric field intensity of the generated electric field spatially stepwise as in the conventional case. , so that it is difficult for current to flow into adjacent electrodes. This embodiment eliminates this consideration and provides even more precise control. That is, between the X and Y deflection electrodes, the fifth
An electric field similar to that described in Figure C is generated in a distributed constant manner. The electric field strength changes spatially and continuously, making it suitable for highly controlled charged beams.

Originally, the purpose of using 8-pole or 16-pole deflection electrodes was to correct disturbances in the electric field in the middle of the X and Y directions. According to the configuration of this embodiment, X.

The shape of the electrode support can be devised so that the Y deflection voltages are appropriately mixed depending on the case, and by allowing current to flow into each other appropriately, even if the electrodes themselves have four poles, An infinite number of types of electrostatic deflectors can be used.

FIG. 3A is a front sectional view of a fifth embodiment of the present invention.

While the above-mentioned embodiments improved the electric field distribution in the horizontal direction, this embodiment improves the electric field distribution in the vertical direction. That is, the stepwise spatial distribution shown in the second diagram above is changed to a continuous spatial distribution of electric field intensity as shown in FIG. 3B, thereby reducing aberrations associated with double deflection. By changing the shape of the electrode support according to the present invention, almost any form of electric field distribution in three-dimensional directions can be realized.

In the above embodiment, SiC is used as the semiconductor electrode support.
We have explained the case of a material with a uniform volume resistivity, but this is not an absolute condition. However, if the resistance value falls within the above range, the same effect as above can be obtained.

Further, in the above embodiment, only the Deflector function that changes the direction of the beam trajectory as a controller of the charged beam was explained, but the application of the present invention is not limited to this. i
gmator function and Le to change the size of the beam diameter
It is clear that even those with ns function exhibit great effects.

Furthermore, silicon carbide has the advantage of extremely high thermal conductivity compared to aluminum oxide, etc., making thermal design very easy. It is easy to braze lead wires, and its bending strength and hardness are slightly higher. For this reason, it can be said to be the optimal material for electrode supports in cases where control electrodes must be fixed with extremely high precision, such as in electrostatic controllers. Furthermore, due to its good wear resistance and chemical resistance, silicon carbide has been widely used in bearings, seals, and parts for chemical pumps, and the stability of the material has been fully demonstrated. This material is particularly suitable for the present invention.

However, the material for the electrode support of the present invention is not limited to silicon carbide, and any material having an appropriate volume resistivity can be used. For example, Tic, A(LN,
Materials such as BN and even metal-mixed aluminum oxide and silicon oxide can also be used.

(Effects of the Invention) According to the present invention, electrostatic control for charged beams allows precise control of charged beams, which was previously impossible, as well as highly controlled elements such as beam position, shape, and diameter. We can provide equipment.

[Brief explanation of the drawing]

FIGS. 1A and 1B, FIG. 2A, and FIG. 3A are front sectional views of electrostatic controllers according to embodiments of the present invention. Figure 1C is
Equivalent circuit diagram. Figures 2B and 2C are plan sectional views. The second diagram and FIG. 3B are diagrams showing the distribution of electric field strength. FIGS. 4A, B, and C are front sectional views of a conventional electrostatic deflector,
Plane sectional view 9 equivalent circuit diagram. FIG. 5A is a partial front sectional view of a conventional electrostatic deflector. FIG. 5B is a plan sectional view of a conventional 8-pole electrostatic deflector, and FIG. 5C is a voltage distribution circuit diagram used therein. DESCRIPTION OF SYMBOLS 1... Electrode support body, 2... Deflection electrode, 3... Charged beam, 4... Frame, 5... Lead wire, 6
,7...notch. Patent Applicant Nichiden Anelva Co., Ltd. Agent Patent Attorney Kenji Murakami-17 = Wt Closed Opening UO3-173325 (6) Procedural Amendment (Method) April 1988 60 1988 Patent Application No. 5633 2, Title of Invention Electrostatic controller for charged beam 3, relationship with the amended case Patent applicant address 5-8-1 Yotsuya, Fuchu-shi, Tokyo Name
Nichiden Anelva Co., Ltd. Representative: An 1) Susumu 4, Agent address: 5-8-16 Yotsuya, Fuchu-shi, Tokyo, Subject of amendment: Drawing 7, Details of amendment: Fig. 2 B, Fig. 2 C2, Fig. 3 A, Drawings related to Figure 3B.

Claims (1)

[Claims] (1) In an electrostatic controller for a charged beam consisting of a control electrode and an electrode support, all or part of the electrode support is made of a semiconductor, and the control An electrostatic controller for a charged beam, characterized in that an electrode is installed outside the electrode support.