JP4795890B2 - Transmission line type blanking apparatus and electron beam exposure apparatus - Google Patents

Description

  The present invention relates to a transmission line type blanking apparatus and an electron beam exposure apparatus, and is particularly used in a spot beam type electron beam exposure apparatus that requires a large current and a small diameter beam to turn on an electron beam at high speed. The present invention relates to a transmission line type blanking apparatus and an electron beam exposure apparatus which are characterized by a configuration for turning off / off.

  Spot beam type electron beam direct writing technology, which directly manipulates an electron beam that is narrowly focused according to the original pattern data without using a mask, can create fine patterns that cannot be done by other methods. This is the only technology that can be said to be used, not only for leading-edge semiconductor integrated circuit research and development, but also for research and development of various devices that require fine patterns such as quantum devices and MEMS, and for small-scale prototyping. (For example, refer to Patent Document 1).

  In addition, in recent years, even in the production of an optical disc master in which a recording pattern has conventionally been generated by a narrowly focused laser beam, for the next generation and the next generation recording methods that require a higher recording density and a fine recording pattern. The use of electron beams has been considered.

  Furthermore, for magnetic disks, as a method to achieve a high recording density that exceeds the perpendicular recording method, a medium in which the recording area itself is separated into individual minute areas has been studied, and a master for creating the minute areas has been created. The use of an electron beam is also considered.

In this technique, it is necessary to frequently turn on / off the electron beam at a high speed according to a fine pattern, and this on / off is performed by a blanking device.
The blanking device in this case is not an electromagnetic type using a coil, but an electrostatic type or an electromagnetic field type using an electrode exclusively for the requirement of high speed. Here, refer to FIG. 6 and FIG. Various conventional blanking devices will be described.

See FIG.
FIG. 6 is a conceptual configuration diagram of a parallel plate blanking device that has been most frequently used in the past. The electrode is composed of a pair of opposed parallel plates or parts that can be regarded as deformations thereof. As seen from the above, the electrode pair terminated openly acts as a capacitor.

The deflection angle in this case is such that the electrode interval is d, the electrode length is h, the electrode width is w, the deflection voltage is V, and the acceleration voltage is φ.
Deflection angle ∝ (V / φ) x (h / d)
It is represented by

  This parallel plate blanking device has a load impedance of almost 0Ω for a fast signal, but is almost ∞Ω for a slow signal, and does not match the characteristic impedance of the feeding cable. Since it has a strong frequency dependence, the voltage applied from the power source is reflected at the electrode, and the deflection electric field actually felt by the electron beam does not rise at high speed and is disturbed.

See FIG.
FIG. 7 is a conceptual configuration diagram of a conventional transmission line type blanking device. In order to solve the above-described impedance mismatch problem, an electrode pair is positioned as a part of the transmission line and its characteristic impedance is set to a power source. The structure and shape dimensions are defined so as to coincide with the feeding cable and the terminating resistance, and it is also called a traveling wave type blanking device (see, for example, Patent Document 2).

As shown in the figure, in principle, the longitudinal direction of the electrode pair is arranged in a direction orthogonal to the traveling direction of the electron beam, and the deflecting electromagnetic field is transmitted by means of an arrangement across the electron beam.
The deflection angle in this case is as follows: electrode interval is d, electrode length is h, electrode width is w, deflection voltage is V, acceleration voltage is φ, termination resistance is z (matches characteristic impedance), and drive current is I ,
Deflection angle ∝ (V / φ) × (h / d) ∝ (V / φ) / z = I / φ
It is represented by

In this case, the characteristic impedance z as a transmission line is basically proportional to the electrode interval d and roughly inversely proportional to the electrode length h. Therefore, in order to increase the deflection capacity with the same deflection voltage V, d is narrowed and h is widened. And z are small values.
Therefore, as is apparent from the above equation, the deflection angle is proportional to the drive current I supplied by the power supply, and for small z, I becomes a large value, making it difficult to realize the power supply.

  In addition, when the impedance impedance of the transmission line is 50Ω in order to achieve impedance matching with 50Ω, which is most widely used as the output impedance of the power source that generates the deflection voltage V and the characteristic impedance of the coaxial cable, a high deflection voltage V is obtained. It becomes necessary and high-speed driving becomes difficult.

  In addition, adopting a characteristic impedance other than 50Ω necessitates the development of dedicated transmission elements such as connectors and coaxial cables, which poses a problem that cost increases cannot be avoided.

  In order to avoid this problem, a helical blanking device (see, for example, Patent Document 3) in which electrodes on both sides with respect to the electron beam are spirally arranged is arranged so as to be moved back and forth several times. A trough-type blanking device using a meander line (for example, see Patent Document 4) has been proposed, and the electrode length is effectively extended by making the electrode pair face the electron beam a plurality of times, so that the characteristic impedance as a transmission line is improved. The deflection ability is increased while avoiding the decrease in size.

In addition, a coaxial line blanking device has been proposed in which high-speed transmission characteristics are given the highest priority and electrode pairs are used as inner and outer conductors of the coaxial line (see, for example, Non-Patent Document 1).
The transmission line blanking device described above has been developed for broadband oscilloscope CRTs and electron beam testers having an acceleration voltage as low as about 5 kV or less.

Furthermore, recently, a transmission line type blanking device different from these has been proposed (see, for example, Patent Document 5), which is also a coaxial line type with the highest priority given to high-speed transmission characteristics. This is a blanking device that is applied to an electron beam exposure system, but the axial direction of the coaxial line is adjusted so that the electromagnetic field for deflecting the electron beam travels in parallel in the same direction along the electron beam. Are aligned.
JP-A-11-097330 U.S. Pat. No. 4,445,041 Japanese Patent No. 3409799 Japanese Patent Application Laid-Open No. 07-104098 Japanese Patent No. 3057042 ELECTRON BEAM TESTING TECHNOLOGY, p. 262-263

However, in order to apply the above-described various blanking apparatuses to an electron beam exposure apparatus with an acceleration voltage as high as about 50 kV or more, there is a serious problem in the deflection capability, and therefore description will be given with reference to FIGS.
In each figure, the left figure is a principle configuration diagram, and the right figure shows the electric field component magnetic field component and its action as seen from above with the line of sight in the traveling direction of the electron beam.
In this case, since the deflection capability is compared, the force received by the electron beam in a steady state is considered rather than a transient high-speed response.

See FIG.
FIG. 8 is an explanatory diagram of the principle of the parallel plate blanking device. In a steady state, charging between both electrodes constituting the capacitor is finished, and no drive current flows.
The electron beam is only deflected by the electric field (V / d) generated between both electrodes, and is compensated by the electrode interval d, the electrode length h, and the deflection voltage V as the acceleration voltage increases.
Incidentally, the right diagram of FIG. 8 is shows a state as viewed from above fit gaze in the traveling direction of the electron beam, F _e denotes the direction of the electric field vector and a negatively charged particle electron receives a force F _e and the opposite direction.

See FIG.
FIG. 9 is a diagram illustrating the principle of the trough-type blanking device. Since the magnetic field component B is parallel to the electron beam, the outer product ([v] × [B]) of the electron velocity v and the magnetic flux density B is 0. ([V] and [B] each represent a vector), no force is applied to the electron beam, and only the deflection by the electric field component (V / d) is applied, as in the parallel plate type.

  However, in this case, since interference between adjacent electrodes folded in a zigzag manner must be avoided and the electrodes cannot be arranged closely without gaps, the length that actually contributes to the deflection is the apparent electrode length h. The deflection capability is lower than that of a simple parallel plate blanking device having an electrode length h.

See FIG.
FIG. 10 is an explanatory diagram of the principle in which the transmission line type blanking device shown in the above-mentioned Patent Document 5 is rewritten into a functionally equivalent shape. There's a problem.
Incidentally, the right side of FIG. 10 are those showing a state seen from above the combined gaze in the traveling direction of the electron beam, F _e represents the direction of the electric field vector.
On the other hand, F _m indicates the direction of the outer product vector of the electron velocity v and the magnetic flux density B, and the electron receives a force in the direction opposite to the outer product vector F _m .

That is, the force received from the magnetic field component is proportional to the outer product ([v] × [B]) of the electron velocity v and the magnetic flux density B, and the direction of this force is the same as the force received from the electric field component (V / d). Opposite direction.
Therefore, the deflection capability is smaller than that of a parallel plate blanking apparatus of the same size, and the ratio becomes more remarkable as the electron velocity v is larger, that is, the acceleration voltage φ is higher. In an electron beam exposure apparatus having a higher acceleration voltage φ, Is a big problem.

  As described above, there is a problem that the deflection capability of a known transmission line type blanking device is inferior to that of a parallel plate type blanking device that is difficult to operate at high speed.

  Accordingly, an object of the present invention is to achieve both high-speed operation and deflection capability within a range necessary for an electron beam exposure apparatus.

FIG. 1 is a diagram illustrating the basic configuration of the present invention. Means for solving the problems in the present invention will be described with reference to FIG.
The diagram on the left shows the principle configuration, and the diagram on the right shows the direction of the electric field vector F _e and the outer product vector F _{m when} viewed from above with the line of sight in the traveling direction of the electron beam.
In order to solve the above-mentioned problem, in the transmission line type blanking device, the present invention deflects the electron beam 5 of a pair of blanking electrodes 1 and 2 constituting a transmission line having a uniform characteristic impedance. The main part to which the electric field is applied has a shape in which the direction along the electron beam 5 is the longitudinal direction, and the power source 4 and the power source 4 so that the deflecting electromagnetic field traveling along the transmission line travels in antiparallel to the traveling direction of the electron beam 5. A termination resistor 3 is arranged.

  That is, as shown in the left figure, the electron beam 5 is deflected in an antiparallel direction opposite to the traveling direction of the electron beam 5, opposite to the transmission line type blanking device of the above-mentioned Patent Document 5. As shown in the right figure, the force received from the magnetic field component B is in the same direction as the force received from the electric field component V / d, and the parallel plate blanking device having the same dimensions is also used. The deflection capability increases, and the ratio increases as the acceleration voltage increases.

  As the acceleration voltage φ increases, the deflection voltage V necessary for deflecting the electron beam 5 is inevitably increased. However, the magnetic field component B contributes positively to the deflection, which is to some extent. Alleviated.

  In this case, one blanking electrode 1 constituting the pair of blanking electrodes 1 and 2 constitutes an inner conductor, the other blanking electrode 2 constitutes an outer conductor covering the inner conductor, and the outer conductor is an inner conductor. It is desirable that the gap between the protrusion and the inner conductor be a passage for the electron beam 5, thereby providing a coaxial in-phase structure for high speed operation. The characteristics can be improved.

  Further, by providing the transmission line type blanking device having the above-described configuration, it is possible to realize an electron beam exposure apparatus having a high speed and excellent deflection capability with a simplified apparatus configuration.

  According to the present invention, the power source and the terminating resistor are arranged so that the force received from the magnetic field component B is in the same direction as the force received from the electric field component V / d. It is possible to obtain a large deflection capability while maintaining the high-speed operation characteristics necessary for the electron beam exposure apparatus in a state where the characteristic impedance is matched, and to avoid complication of the apparatus configuration.

  According to the present invention, a main part for applying a deflection electric field to an electron beam of a pair of blanking electrodes forming a transmission line having a uniform characteristic impedance is shaped so that the direction along the electron beam is a longitudinal direction. The power source and the terminating resistor are arranged so that the deflection electromagnetic field that travels in the direction of the electron beam travels in antiparallel to the traveling direction of the electron beam.

  In particular, in order to improve high-speed operation characteristics, one electrode constituting a pair of blanking electrodes is an inner conductor, the other electrode is an outer conductor that covers the inner conductor, and the outer conductor protrudes toward the inner conductor. The gap between the protrusion and the inner conductor is used as an electron beam passage.

Here, the spot beam type electron beam exposure apparatus according to the first embodiment of the present invention will be described with reference to FIGS.
See Figure 2
FIG. 2 is a conceptual block diagram of the spot beam type electron beam exposure apparatus according to the first embodiment of the present invention. The electron source 21, the extraction electrode 22, the condenser lens 23, the ground plate 24, the condenser lens 25, the transmission line type block is shown. A ranking device 10, a blanking aperture 26, an objective aperture 27, a stigmator 28, an objective lens 29, a deflector 30, and a sample stage 31 on which a sample 32 is placed are provided.

  The electron beam 33 extracted from the electron source 21 is accelerated by, for example, an acceleration voltage of 100 kV and forms an image once at the center of the transmission line type blanking device 10 by the two condenser lenses 23 and 25.

Thereafter, the electron beam 33 is focused by the objective aperture 27, then is deflected to a predetermined position by the deflector 30, and focused on the sample 32 by the objective lens 29.
The stigmator 28 is used for correcting astigmatism.

  Here, when the electron beam 33 is turned off, the electron beam 33 is deflected to the outside of the opening provided in the blanking aperture 26 by the transmission line type blanking device 10 so that the electron beam 33 is blanked. Shut off with.

See Figure 3
FIG. 3 is an explanatory diagram of the configuration of the transmission line type blanking device 10 used in the spot beam type electron beam exposure apparatus according to the first embodiment of the present invention. The internal conductor is in phase with the coaxial line excellent in high-speed operation characteristics. 11 and an external conductor 12 included inside so as to cover it, a transmission line using blanking electrodes was formed.

As an example, as shown in the schematic cross-sectional view of the right figure, for example, the outer conductor 12 has a square of about 10 mm square and has a protruding portion 13 protruding inward at a portion facing the inner conductor 11. The inner conductor 11 is provided with a gap of 1 mm from the protrusion 13, and the electron beam 33 is subjected to a deflection action from an electromagnetic field traveling through the gap when passing through the gap.
In this case, the portion where dimensioning is omitted is finely adjusted so that the characteristic impedance z as a transmission line is 50Ω.

  The output impedance of the power supply 16 that generates the deflection voltage 13V is 50Ω, and is connected to feedthroughs 41 and 42 that penetrate the vacuum partition 40 by coaxial cables 43 and 44 having a characteristic impedance of 50Ω.

  Thus, since the characteristic impedance is selected to be 50 Ω, the most widely used value, a commercially available hermetic seal product with a bandwidth of 20 GHz is easily available and used for the feedthroughs 41 and 42.

Inside the vacuum bulkhead 40, it is connected to the transmission line type blanking electrode described above, and is connected to the termination resistor 17 on the atmosphere side through the feedthrough 42 penetrating the vacuum bulkhead 40 again at the other end. Has been.
The outer conductor 12 constituting the transmission line type blanking electrode is provided with an entrance 14 and an exit 15 for the electron beam 33.

When the deflection voltage is 13 V, the power consumed by the termination resistor 17 is not a large value of 169 V ² /50Ω=3.4 W at maximum, but the natural air-cooled termination resistor 17 with the radiation fins 18 is sufficient. is there.

  In a state where the deflection voltage 13V is constantly applied, the electron beam 33 having an acceleration voltage of 100 kV is deflected at an angle of 3 mrad, blocked by the blanking aperture 26 downstream, and the beam is turned off.

See Figure 4
FIG. 4 is a diagram illustrating the principle of the transmission line blanking device according to the first embodiment of the present invention, the left diagram is a diagram illustrating the principle configuration, and the right diagram is a top view with the line of sight aligned with the traveling direction of the electron beam. Shows the electric field component and the magnetic field component and their actions.

  As shown in the left figure, the terminal resistor z and the power source are arranged so that the electromagnetic field for deflecting the electron beam travels in an antiparallel direction opposite to the traveling direction of the electron beam.

  As is clear from the action shown in the right figure, the force received from the magnetic field component B is in the same direction as the force received from the electric field component V / d, so that the parallel plate blanking of the same size on which only the electric field component V / d acts is applied. The deflection capability is greater than that of the electrode.

For example, when the acceleration voltage φ is 100 kV, the ratio of (electric field only deflection capability) and (electric field + magnetic field deflection capability) is:
(Electric field only deflection capability): (Electric field + magnetic field deflection capability) = 1: 1.55
The ratio increases as the speed of electrons increases, and as the acceleration voltage φ increases.

  As the acceleration voltage φ increases, the deflection voltage V necessary for deflecting the electron beam is inevitably increased. However, the magnetic field component B contributes positively to the deflection, which is somewhat relaxed. Is done.

See Figure 5
FIG. 5 is an explanatory diagram of the deflection capability of the blanking device. When the acceleration voltage is as low as about 1 kV or less, the parallel plate blanking device represented by (a) / (d) or (b) / (d) The deflection capability of the trough-type blanking device represented by is comparable to the transmission line-type blanking device of the present invention.

However, at a high acceleration voltage such as an acceleration voltage of about 50 kV or 100 kV used as an electron beam exposure apparatus, a trough type blanking apparatus and a transmission line type blanking apparatus for an electron beam exposure apparatus disclosed in Patent Document 5, In particular, it can be seen that the deflection capability of the transmission line type blanking device shown in Patent Document 5 represented by (c) / (d) is significantly reduced.
Note that the deflection capacity of the parallel plate blanking device is relatively small, but this is inherently difficult to operate at high speed as described above.

  For example, the transmission line type blanking device of the present invention is deflected at an acceleration voltage of 50 kV in order to obtain the same deflection capability as compared with the transmission line type blanking device having excellent high frequency characteristics shown in Patent Document 5. The voltage is reduced to 42%, 29% at 100 kV, and only 17% and 8.5% of power are required.

  This is also true for lost power lost as heat generation in the middle of the transmission line, compared with the transmission line type blanking device shown in Patent Document 5 where cooling with a refrigerant is preferred. Thus, such a complicated cooling means is not necessary, and the natural air-cooled termination resistor 17 with the heat radiating fins 18 is sufficient as described above, so that the apparatus configuration is greatly simplified.

  As described above, in the present invention, in addition to increasing the deflection capability by the electrode length h of the blanking electrode, a high deflection voltage V is not required even if the transmission line characteristic impedance z is 50Ω. Realization is facilitated, and commercial high-speed transmission elements can be used.

  As described above, the first embodiment of the present invention has been described. However, the present invention is not limited to the configuration and conditions described in the first embodiment, and various modifications can be made. Is described as a blanking electrode having a coaxial line structure, but is not necessarily limited to the coaxial line structure, and a configuration in which a parallel plate electrode is matched and terminated with a termination resistor z may be used.

  In the above description of the embodiment, the blanking apparatus used in the spot beam type electron beam exposure apparatus is described. However, the blanking oscilloscope is not limited to the electron beam exposure apparatus and has a low acceleration voltage. It may be used as a blanking device for a CRT for use or an electron beam tester.

  Furthermore, it may be used as a blanking device of a charged beam irradiation apparatus that irradiates a charged beam such as an ion beam. In this case, the current direction of the charged beam is opposite to the current direction of the electron beam. It is necessary to arrange the power source and the terminating resistor so that the deflection electromagnetic field traveling on the transmission line travels in antiparallel with the traveling direction of the charged beam.

  The numerical values such as the interval, size, voltage, etc., exemplified in the above embodiment are merely examples, and may be appropriately changed according to the apparatus configuration / scale.

  As a practical example of the present invention, a blanking apparatus used in a spot beam type electron beam exposure apparatus is typical. However, the present invention is not limited to an electron beam exposure apparatus, but is used for the blanking of equipment using various electron beams. The present invention can also be applied to a ranking apparatus, and can also be used as a blanking apparatus for a charged beam irradiation apparatus such as an ion beam.

It is explanatory drawing of the fundamental structure of this invention. 1 is a conceptual configuration diagram of a spot beam type electron beam exposure apparatus according to a first embodiment of the present invention. 1 is a configuration explanatory diagram of a transmission line type blanking device used in the spot beam type electron beam exposure apparatus of Example 1 of the present invention. FIG. It is principle explanatory drawing of the transmission line type blanking apparatus of Example 1 of this invention. It is explanatory drawing of the deflection capability of a blanking apparatus. It is a conceptual block diagram of the conventional parallel plate type blanking apparatus. It is a conceptual block diagram of the conventional transmission line type | mold blanking apparatus. It is principle explanatory drawing of a parallel plate type blanking apparatus. It is a principle explanatory view of a trough type blanking device. It is principle explanatory drawing which rewritten the transmission line type blanking apparatus shown by patent document 5 into the functionally equivalent shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blanking electrode 2 Blanking electrode 3 Termination resistor 4 Power supply 5 Electron beam 10 Transmission line type blanking apparatus 11 Inner conductor 12 Outer conductor 13 Protrusion part 14 Inlet 15 Outlet 16 Power supply 17 Termination resistor 18 Radiation fin 21 Electron source 22 Extraction electrode 23 Condenser lens 24 Ground plate 25 Condenser lens 26 Blanking aperture 27 Objective aperture 28 Stigmeter 29 Objective lens 30 Deflector 31 Sample stage 32 Sample 33 Electron beam 40 Vacuum bulkhead 41 Feedthrough 42 Feedthrough 43 Coaxial cable 44 Coaxial cable 44

Claims (3)

A main portion for applying a deflection electric field to the electron beam of a pair of blanking electrodes forming a transmission line with uniform characteristic impedance has a shape in which the direction along the electron beam is a longitudinal direction, and travels along the transmission line A transmission line type blanking device, wherein a power source and a terminating resistor are arranged so that a deflecting electromagnetic field travels in antiparallel with the traveling direction of the electron beam. One blanking electrode constituting the pair of blanking electrodes constitutes an inner conductor, and the other blanking electrode constitutes an outer conductor covering the inner conductor, and the outer conductor protrudes toward the inner conductor. 2. The transmission line type blanking device according to claim 1, further comprising: a projecting portion, wherein a gap between the projecting portion and the inner conductor is used as an electron beam passage. An electron beam exposure apparatus comprising the transmission line type blanking device according to claim 1.

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