JPS608581B2 - Blanking device in electron optical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron optical planking device, and particularly to a planking device suitable for use in an electron beam lithography system.

FIG. 1 is an example of a conventional planking device in an electron optical system.

An electron beam 1 generated from an electron gun 2 is focused into a small beam by a reducing lens 3, and is focused on a sample 8 by an objective lens 6.
Focus on the surface. On the other hand, the electron beam 1 is deflected left and right, front and back by the deflection lens 7, and can freely scan the surface of the sample 8. Furthermore, planking signal line 13
Due to changes in the planking signal 14 supplied to the planking plates 4, 4 via the planking plates 4, 4,
As the electric field between 4 changes, the electron beam 1 changes as
It is deflected and hits the planking diaphragm 5, and irradiation or non-irradiation of the sample 8 can be controlled.

The mirror body 9 that houses these electron optical systems is usually made of metal, taking into account the effects of vacuum and external magnetic fields.

/ Also, the mirror body 9 is connected to the ground at the ground point lo at the lower part. FIG. 2 is an enlarged view of the planking device shown in FIG. 1.

The planking signal 14 passes through the hermetic seal 12 and is applied to the planking plate 4 via the planking signal line 13.

When a positive voltage is applied to the left side plate of the planking plate 4 and the right side plate is grounded, the electron beam 1 is drawn by the left side plate and hits the left side of the planking aperture 5 below. On the contrary, when the left side of the planking plate 4 is grounded and the right side is applied with a positive voltage, the electron beam 1 hits the right side of the planking aperture 5.

Further, when no planking voltage is applied, the electron beam 1 passes through the planking aperture 5 and reaches the sample 8. In this way, planking and amp ranking can be controlled. Note that the planking plate 4 is supported while being insulated from the mirror body 9 by an insulator 11. FIG. 3 is a functional diagram of the planking signal generation circuit.

Depending on the opening/closing operation of the planking switch 15, the planking signal 14 becomes the planking voltage 16 or the ground voltage. When the ground voltage is applied, the electron beam 1 is in an amplifier blanking state, and the electron beam 1 passes through the center of the blanking aperture 5 and is irradiated onto the sample. Note that the load resistance R is a current limiting resistance of the planking switch 15. The opening and closing of this planking switch 16 is controlled by the device control circuit in the electron beam lithography system, and is open during lithography and open when not lithographic.

FIG. 4 is an equivalent circuit in which the planking signal generation circuit, the planking plate 4, and the mirror body 9 are represented by an electric circuit.
When the planking switch 5 is open (during non-drawing), a positive voltage is applied to the left side of the planking board 4.

In addition, there is a stray capacitance C between the planking plate 4 and the mirror body 9,
There is C2, which is also charged with a positive voltage applied to it. Now, when the planking switch group 5 is closed (during drawing), the positive charge on the left side of the blanking board turtle passes through the planking switch 15 and combines with the negative charge on the right side of the planking board turtle (current 1). .

In addition, stray capacitance C. The electric charge stored in becomes a current 12, which flows and discharges as shown in the figure. This current 12 flows between ab and ab in the figure, and this ab and ab is a mirror portion. In this way, a current flows through the mirror body 9 due to the stray capacitance C,
Electron beams have a negative effect.

In addition, in the case of this figure, there is no charge flow because both ends of the stray capacitance C2 are at ground potential.As mentioned above, the planking device in the conventional electron optical system When starting to irradiate a sample with an electron beam, a current flows through the mirror due to the stray capacitance between the flanking plate and the mirror, and the magnetic field caused by this current has the disadvantage of affecting the electron beam.

In other words, the conventional electron beam lithography apparatus has the disadvantage that the figure at the beginning of writing on the sample is not clear, resulting in a significant drop in accuracy. SUMMARY OF THE INVENTION An object of the present invention is to provide an electro-optical planking device that can draw accurate patterns by providing a shield guard to block current flowing through the mirror body when the planking voltage changes.

Based on the above-mentioned considerations regarding electron beam lithography equipment, the present invention has discovered that the cause of poor accuracy in the starting position of drawing a figure is that current flows through the mirror due to the stray capacitance between the planking plate and the mirror. A shield guard is provided as a means to confirm that the current is at a point where it affects the line and to stop this current. Figure 5 is a sectional view of the main part of an embodiment of the present invention. .

In the figures, the same reference numerals as in FIGS. 1 to 4 represent the same or equivalent parts. In this embodiment, a current of 1 is applied to the mirror body 9.
A shield guard 19 is inserted between the mirror body 9 and the planking plate 4 in order to prevent the flow of water. FIG. 6 shows an equivalent circuit when this shield guard 19 is included. In addition,
The shield guard 89 is connected to the ground side of the planking switch box from the guard wire 2M. In Figure 6,
When the planking switch 15 is open, the planking plate 4
, and stray capacitance C', a blanking voltage blind 6 is added.

When the planking switch turtle 5 is closed, the electric charge on the planking plate turtle becomes electric as described above. Further, the charge of the stray capacitance C' flows through the guard line 28 as a current 1'2. Therefore, no current flows through the mirror body 9, and the electron beam 1 is not affected, and a good amplifier ranking operation is performed.When the planking switch turtle 5 changes from closed to open, the current flows in the direction It can be explained in the same way, except that it is reversed.

In addition, in this case, since it is a change from full drawing to non-writing, even if a current flows, it will not affect the L sample. , an insulator 21 is interposed between the mirror body 9 and the shield guard 19.

In this embodiment, the line bc of the equivalent circuit in FIG. 6 is removed, but since both ends of the stray capacitance C3 are at ground potential, no current flows through the mirror body. Therefore, effects similar to those described above can be obtained. In addition, in each of the above embodiments, it is obvious that the same effect can be obtained even if the shield guard vine 9 is not cylindrical as shown in FIG. 5, but has a shape that covers the planking board turtle. be.

As is clear from the above explanation, ``According to the present invention, when controlling planking to ampranking by changing the electric field of the planking plate, no current flows through the mirror body, so good drawing results can be obtained. can get.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing an example of a conventional planking device with an electron optical system, Fig. 2 is a cross-sectional view of the planking device in Fig. 1, and Fig. 3 is a diagram showing an example of a planking signal generation circuit. 4 is an electrical equivalent circuit diagram of the planking device in FIG. 1, FIG. 5a is a sectional view of an example of the planking device according to the present invention, FIG. The figure is an electrical equivalent circuit diagram of the planking device in FIG. 5, and FIG. 7 is a sectional view of an embodiment of the present invention.
・Planking aperture "6... Opposed lens, 7... Deflection lens, 8... Sample LS... Mirror body, Tensile 4... Planking signal, Wing 9... Shield guard. Spear 1, Rare 2, 3 figures, 4 figures, 5 figures, 6 figures, 2′ 7 figures.

Claims (1)

[Claims] 1. A means for focusing the electron beam on the sample, a means for deflecting the electron beam on the sample, and a means for preventing the electron beam from reaching the sample.
A shield guard disposed between the blanking plate and a mirror body so as to cover the blanking plate in an electron optical blanking device equipped with a blanking plate that deflects and blanks an electron beam. A blanking device for an electron optical system, further comprising: and means for holding the shield guard and the mirror at the same potential.