JPH0766869B2 - Plasma x-ray source - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an X-ray source for an X-ray lithographic apparatus for LSI manufacturing, and more particularly to a plasma X-ray source for improving the X-ray intensity.

[Conventional technology]

As a conventional device, for example, one disclosed in Japanese Patent Laid-Open No. 60-151945 is known. As shown in FIG. 7, it is composed of a charging power source 1, a charging resistor 2, a capacitor 3, a discharging switch 4, an electric circuit 7, and a discharging device 5. 16
Is an exposure mask, 17 is an exposure wafer, and 19 is an aligner. The discharge device 5 includes an exhaust device (not shown), an insulating spacer 18, and electrodes 11 and 12. In operation, power is first supplied to the capacitor 3 from the appropriately controlled charging power source 1 via the charging resistor 2 to charge the capacitor 3 to a predetermined voltage.
After that, the discharge switch 4 is closed by an external factor (not shown), and passes through the electric path 7 (7 is composed of the high-voltage transmission plate 8, the low-voltage transmission plate 9, and the insulating spacer 10) and the pair of discharge devices 5 has The above voltage is applied between the electrodes 11 and 12 to cause discharge, and plasma is generated. Thereafter, the energy stored in the capacitor is supplied to generate a plasma pinch and emit X-rays 14. Let The protection resistor 6 is provided in the discharge device 5 to absorb the energy of the capacitor 3 when no discharge occurs. This X-ray 14 is applied to a resist-coated wafer 17 through an X-ray extraction window 15 and an X-ray mask 16 to expose it. Such a conventional device is still in the research stage, and an oil-immersed paper capacitor or an oil-immersed plastic film capacitor which is generally used for electric power is used as the power supply capacitor.

[Problems to be solved by the invention]

The prior art described above has a problem in that the rise time of the discharge current is not taken into consideration and only a weak X-ray output can be obtained. That is, when the rise time of the discharge current is slow, the magnetic force for pinching the plasma generated between the electrodes becomes weak, and as a result, the X-ray output tends to become weak. In the case of the conventional technique, since the electric path connecting the discharge switch and the discharge tube is relatively long and the inductance of this electric path cannot be reduced, it is difficult to obtain a discharge current with a fast rise time.

It is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art and to provide a plasma X-ray source capable of obtaining a strong X-ray output.

[Means for solving problems]

In the present invention, in order to achieve the above object, a capacitor bank is formed into a parallel conductor plate and a plurality of ceramic capacitors are formed in a sun-gate shape, and an electric path is provided from at least one place of the parallel conductor plate as a unit, and a plurality of electrically conductive plates are electrically connected. The units were connected in parallel.

[Action]

Since a plurality of ceramic capacitors are arranged between parallel plates, it becomes a distributed constant circuit in the circuit, and if a certain voltage is charged and short-circuited in the circuit, a rectangular wave current will flow, The rising steepness of is extremely large. The same phenomenon occurs in the case of a discharge device having a low impedance load, and the rising steepness of the current waveform becomes extremely large. Since the rising steepness of the discharge current becomes extremely large in this way, the plasma heating temperature of the discharge device rises, and strong X-ray radiation can be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Here, the same components as those in the embodiment of FIG. 7 are designated by the same reference numerals. The ceramic capacitor 20 is provided between the high-voltage conductor plate 22 and the low-voltage conductor plate 21 in the shape of a sun gate.
FIG. 2 shows one unit plate of FIG. 1 and two units stacked. One side of the conductor plate is coaxial cable 23
Is connected to the discharge switch 4 via the transmission plate 8 and is connected to the discharge tube 5 via the transmission plates 8 and 9.

When the discharge switch 4 is put in after the ceramic capacitor 20 is charged, the electric charge of the ceramic capacitor 20 is rapidly released between the electrodes 11 and 12. At this time, this circuit becomes a distributed constant circuit, and the electric charge of the ceramic capacitor 20a at the shortest position of the electric path to the discharge tube first reaches between the electrodes 11 and 12, and after a certain delay time, the ceramic capacitor 20b sequentially. , 20c, ..., 20h charge flows in. For this reason,
The discharge current waveform is as shown in FIG. Therefore, as compared with the discharge current waveform (b) of the conventional example, a discharge current waveform having a faster rise time can be obtained. As a result, between the electrodes 1
Since the magnetic force required to pinch the plasma at 1, 12 is strong and the heating temperature rises, a strong X-ray output can be obtained. Further, in the case of the present invention example, the high-voltage conductor plate is inserted inside, and the structure of the capacitor bank 24 is highly safe against electric shock. Further, since it has a unit plate structure, it also has a unique effect of facilitating maintenance such as change of capacitor capacity.

4 and 5 show another embodiment of the present invention. FIG. 5 shows a view of AA ′ of FIG. The configuration is almost the same as that of FIG. 2, but shows a real-scale capacitor bank when used as an X-ray source for X-ray lithography.
The charge energy of a normal capacitor bank is given by the following equation.

However, C: capacitor capacity (μF), V: charging voltage (kV) The required energy is several kJ. Now E = 3.125 (kJ) V = 50
If it is (kV), the required capacitance C = 2.5 (μF). Generally, the capacity of high voltage ceramic capacitors is about 2000pF, so the number of mounted capacitors is 1250. Therefore, the method of mounting a large number is important. The unit plate is 13
A total of 26 pieces are arranged in two rows. This unit plate is sandwiched with an insulator 25, and the high voltage conductor plates 22 are stacked. In this way, the structure is such that 48 sets of unit plates are stored in the capacitor bank 24. The number of mounted capacitors is 1248 (= 26 x 48). The capacitor bank 24 is a partition plate 24a so as not to apply a load to the ceramic capacitor itself.
Has a four-stage structure. In the case of the example of the present invention, a large number of ceramic capacitors can be mounted, and since the unit structure is adopted, the current distribution during discharge can be made uniform in each unit, and there is an effect of obtaining a discharge current with good reproducibility.

FIG. 6 shows still another embodiment of the present invention. Only the top view of the capacitor bank 24 is shown. The connection with the discharge switch is the same as in FIG. FIG. 6 shows a case where a ceramic capacitor is arranged between parallel plates having a large area. A current blocking slit 26 is provided to obtain a uniform current distribution during discharge. As a result, the same effect as in FIG. 4 can be obtained, and a strong X-ray output can be obtained.

In the embodiments of FIGS. 2, 4, and 6, all the capacitors are ceramic capacitors, and it is said that the life of the number of times of charging and discharging is extended by about two digits as compared with the capacitors using the conventional oil-immersed film. It also has an incidental effect.

〔The invention's effect〕

According to the present invention, a capacitor bank is a parallel conductor plate having a plurality of ceramic capacitors in the shape of a sun-gate, and an electric path is provided from at least one position of the parallel conductor plate as a unit, and a plurality of units are connected in parallel. Therefore, it is possible to obtain a fast rising discharge current,
Since the plasma between the electrodes can be strongly pinched in a short time, a strong X-ray output can be obtained.

[Brief description of drawings]

1 is an embodiment of the present invention, FIG. 2 is another embodiment of the present invention, FIG. 3 is a typical discharge current waveform, FIG. 4 is another embodiment of the present invention, and FIG. Top view of another embodiment of the invention, sixth
FIG. 7 shows another embodiment of the present invention, and FIG. 7 shows a conventional example. 5 ... Discharge device, 11, 12 ... Electrodes, 21, 22 ... Conductor plate, 20
…… Ceramic capacitor, 26 …… Current blocking slit.

Claims (2)

[Claims] 1. A plasma X-ray source comprising a discharge device having at least a pair of electrodes provided in a vacuum container, and an electric circuit for supplying a large pulse current to the discharge device, and a capacitor bank. A plasma X-ray source characterized in that a plurality of ceramic capacitors are connected to each other in the shape of a sun deer, and a plurality of units are electrically connected in parallel as a unit in which an electric path is provided from at least one location of a parallel conductor plate. . 2. A plasma X-ray source comprising a discharge device having at least a pair of electrodes provided in a vacuum container, a circuit for supplying a large pulse current to the discharge device, and a capacitor bank. 2. A plasma X-ray source, characterized in that a plurality of ceramic capacitors are connected to each other in a sun-gate shape, and a parallel current blocking slit is provided on the parallel conductor plate.