JPS6245663B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for electrostatic deflection of charged particle beams. In general, electrostatic deflection devices are widely used in electron beam exposure devices, electron microscopes, cathode ray tubes, image pickup tubes, and the like to deflect beams at high speed and precision or to adjust the cross-sectional shape of beams.

In an electrostatic deflection device used in such fields, in order to widen the deflection range, it is desirable that the deflection electric field has a cosine distribution to minimize deflection aberration over a wide range.

Conventionally, such a deflection device is a multipole type electrostatic deflection device in which 12 electrode elements D ₁ to D ₁₂ are insulated and sequentially arranged at equal intervals on the circumference, as shown in Fig. 1. The device is known (Japanese Unexamined Patent Application Publication No. 1983-1999)
(Refer to Publication No. 134369).

As shown in the figure _, the deflection _voltage + _{Vx in} the
−Vx _is applied, _{and a} Y _- direction deflection voltage +Vy,
By applying -Vy and setting the remaining four electrode elements to ground (zero) potential, the deflection electric field has a cosine distribution. In this case, the third-order Fourier component (electric field component involved in third-order aberration) with respect to the angular coordinate θ of the potential distribution can be removed, but the higher-order Fourier components include terms of fifth order or higher. There is. By eliminating this fifth-order term, aberrations can be reduced over a wider range.

An object of the present invention is to provide an electrostatic deflection device that can remove third-order and fifth-order electric field components regarding the angular coordinate θ of potential distribution.

The purpose is to arrange 60
Of the electrode elements, the central angles are 12°, 24°, 60°,
96°, 108°, or central angle 36°, 48°, 60°, 156
10 electrode elements located at 168° and 10 electrode elements located opposite these electrode elements to the center of the circle.
These electrode elements are used as deflection electrodes in the X direction.
This is achieved by using 20 electrode elements that are 90° out of phase with each other as deflection electrodes in the Y direction, and the remaining 20 electrode elements as ground electrodes. .

Hereinafter, the present invention will be explained in detail with reference to the accompanying drawings.
First, the principle of the present invention will be explained using FIGS. 2 to 5. In FIGS. 2 to 5, 60 electrode elements D ₁ to D ₆₀ are sequentially arranged at equal intervals on the circumference. For convenience of explanation, only some electrode elements are illustrated.

In Figure 2, two electrode elements on the X axis
Apply voltages of +1V and -1V to D ₁ and D ₃₁ , respectively,
Due to its symmetry, the potential distribution Φ ₁ when the other electrode elements D ₂ to D ₃₀ and D ₃₂ to D ₆₀ are set to 0 potential can be expressed as follows by expanding with respect to the angular coordinate θ.

(However, m is the order of expansion, and represents a coefficient that depends on the cylindrical coordinates r, z.) From equation (1), the potential distributions Φ _Q and Φ _R at points Q and R, which are symmetrical to point P in the figure, are , it can be seen that the following relationship exists for the potential distribution Φ _P at point P.

Φ _P = Φ _Q Φ _P = −Φ _R ………(2) Also, as shown in Fig. ₃ , +
1V, -1V is applied to the electrode element D ₃₂ , and the other electrode elements D ₂ to D ₃₁ and D ₃₃ to _{D 60} are set to 0 potential. The potential distribution Φ ₂ is the potential distribution shown in FIG. 2 by +6゜Since it is rotated counterclockwise, It can be expressed as

Similarly, as shown in Figure 4, the central angle is 12°,
Located at opposite positions at 24°, 60°, 96°, and 108°
Among the 20 electrode elements, electrode elements D ₂ , D ₃ , D ₆ ,
+1V for D ₉ , D ₁₀ , D ₅₂ , D ₅₃ , D ₅₆ , D ₅₉ , D ₆₀ , electrode elements D ₂₂ , D 23 , D ₂₆ , D ₂₉ , D ₃₀ , _{D 32 ,} D ₃₃ ,
The potential distribution Φ _V when applying -1V to D ₃₆ , D ₃₉ , D ₄₀ and setting the other electrode elements to 0 potential is: becomes.

Also, as shown in Figure 5, the central angles are 36° and 48°.
20 in opposite positions at ゜, 60゜, 156゜, 168゜
Among the electrode elements, electrode elements D ₄ , D ₅ , D ₆ ,
+1V to D ₁₄ , D ₁₅ , D ₄₇ , D ₄₈ , D ₅₆ , D ₅₇ , D ₅₈ , electrode elements D ₁₇ , D ₁₈ , D ₂₆ , D ₂₇ , D ₂₈ , D ₃₄ , D ₃₅ ,
The potential distribution Φ _U when applying -1V to D ₃₆ , D ₄₄ , and D ₄₅ and setting the other electrode elements to 0 potential is: becomes.

In equations (4) and (5), for m=0, 1, 2, and 3, if the values in the curly brackets are calculated for the case of θ=0, It can be seen that the 3θ and 5θ components are removed, respectively.

Note that the deflection electric field distribution in the Y direction is only changed in phase by 90°, and the 3θ and 5θ components are removed as in the case of the X direction described above.

Therefore, as shown in FIG. 6 or 7,
60 electrode elements arranged sequentially and evenly spaced around the circumference
Electrode elements D ₂ , D ₆₀ ; D ₃ , D ₅₉ located at central angles of 12°, 24°, 60°, 96°, and 108° among D ₁ to D ₆₀ (shown only by numbers for simplicity) ; _D6 , _D57 ;
D ₉ , D ₅₃ ; D ₁₀ , D ₅₂ and electrode elements located opposite to these electrode elements with respect to the center, D ₃₂ , D ₃₀ ;
D ₃₃ , D ₂₉ ; D ₃₆ , D ₂₆ ; D ₃₉ , D ₂₃ , D ₄₀ , D ₂₂ (6th
), or center angle 36°, 48°, 60°, 156°, 168
Electrode elements located at °, D ₄ , D ₅₈ ; D ₅ , D ₅₇ ;
D ₆ , D ₅₆ ; D ₁₄ , D ₄₈ ; D ₁₅ , D ₄₇ and D ₃₄ , D ₂₈ located opposite to the center of these electrode elements;
D ₃₅ , D ₂₇ ; D ₃₆ , D ₂₆ ; D ₄₄ , D ₁₈ , D ₄₅ , D ₁₇ (7th
The deflection voltage in the X direction +
Vx, -Vx (indicated _by
D ₁₅ ; D ₁₈ , D ₁₄ ; D ₂₁ , D ₁₁ ; D ₂₄ , D ₈ ; D ₂₅ , D ₇ and D ₄₇ , D ₄₅ ; D ₄₈ , D 44 ; D ₅₁ , D ₄₁ ; _{D 54 ,} D ₃₈ ;
D ₅₅ , D ₃₇ (Figure 6), or D ₁₉ , D ₁₃ ; D ₂₀ , D ₁₂ ;
D ₂₁ , D ₁₁ ; D ₂₉ , D ₃ ; D ₃₀ , D ₂ and D ₄₉ , D ₄₃ ;
D ₅₀ , D ₄₂ ; D ₅₁ , D ₄₁ ; D ₅₉ , D ₃₃ ; D ₆₀ , D ₃₂ (7th
Deflection voltages +Vy, -Vy (indicated by y and -y for simplicity) in the Y direction are applied to the electrodes (Figure), and the remaining 20 electrode elements are at ground (zero) potential (indicated by "0" for simplicity). ), it is possible to form a deflection electric field distribution in which 3θ and 5θ components, which are Fourier components involved in third- and fifth-order aberrations, are removed.

As described above, the deflection device of the present invention, like the conventional electrostatic deflection device shown in FIG. 1, directly applies deflection voltages in both the X and Y directions to the electrode elements without adding a dividing resistor circuit. This not only has the effect of deflecting the charged particle beam with high accuracy and high speed, but also removes not only the third-order aberration but also the higher-order Fourier component 5θ involved in the fifth-order aberration. This has the effect of deflecting the beam over a wider range.

Note that the electrode elements used in the present invention are not limited to the rod-shaped or cylindrical electrode elements illustrated in FIGS. 4 to 7, but may be plate-shaped electrode elements. Also,
As seen in the embodiments of FIGS. 8-10,
Using 60 electrode elements of various identical configurations, such as a hollow cylinder divided at equal intervals, a trapezoidal hollow cone divided at equal intervals, and a hollow cylinder divided into spirals at equal intervals. Similar effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a conventional electrostatic deflection device, FIGS. 2 to 5 are diagrams explaining the principle of the present invention, and FIGS. 6 and 7 are plan views showing embodiments of the deflection device of the present invention. ,
FIGS. 8 to 10 are perspective views partially illustrating configurations of electrode elements used in the present invention. Codes in the figure: D ₁ to D ₆₀ : Electrode element, X, -X:
X direction deflection voltage, Y, -Y: Y direction deflection voltage.

Claims (1)

[Claims] 1. Of the 60 electrode elements sequentially arranged at equal intervals on the circumference, the central angles are 12°, 24°, 60°, 96°, and 180°.
The 10 electrode elements located at 90° and the 10 electrode elements located opposite to the center are the deflection electrodes in the X direction. A charged particle deflection device characterized in that 20 electrode elements located at different phases are used as Y-direction deflection electrodes, and the remaining 20 electrode elements are used as ground electrodes. 2 Among the 60 electrode elements arranged at regular intervals on the circumference, the central angles are 36°, 48°, 60°, 156°, and 168°.
The 10 electrode elements located at 0° and the 10 electrode elements located opposite to the center are used as deflection electrodes in the X direction, and each of these 20 electrode elements has a 90° phase. in different positions
20 electrode elements are used as deflection electrodes in the Y direction, and the remaining
A charged particle deflection device characterized by using 20 electrode elements as ground electrodes.