JPH01236598A - Plasma x-ray source - Google Patents

Abstract

PURPOSE:To improve reliability by sandwitching plural number of ceramic capacitors between parallel conductive plates, circulating air or an insulation gas inside of the capacitor bank, and by providing a dust collector of the dust within a capacitor bank, in a capacitor bank. CONSTITUTION:An air circulator 21 and a filter 22 are provided in the inside of a bank 1, and ventilation is made through an air duct 23. The dust between conductive plates 3 and 4 is eliminated via an airflow change plate 24. Consequently when a capacitor is charged, a strong electric field is generated between the conductive plates, the dust in the inside of the bank is electrified, and when charging and discharging are repeated (generally charge cycle number of 100ms, and discharge cycle number of mus), the dust gathers on the conductive plates, and short-circuit is prevented by the current collecting action with an electrical field. Consequently the use of gas, particularly an insulation gas SF3, etc., as a ventilated gas except air, can contribute the improvement of the voltage resistance in the inside of the bank.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray source for an X-ray lithography apparatus for LSI manufacturing, and particularly to a power source suitable for using a plasma X-ray source as a light source.

[Conventional technology]

As a conventional device, there is one shown in Japanese Patent Application Laid-Open No. 60-151945, which includes a capacitor bank and a switch.

X-ray generating discharge tubes, etc. are connected by electrical circuits. Plasma X
A high frequency (10 6 to 10 9 times) high speed pulse large current source is required for the power source of the line source. Of the above discharge circuits,
Switches and discharge tubes can be replaced by replacing electrodes, but capacitors require replacing the entire bank. The lifespan of oil-immersed capacitors currently used for electric power is 10” to 106
times and short.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into account the lifespan of the capacitor bank, and the capacitor bank itself must be replaced in less than - years. For this reason, it has a long life (108~
The use of ceramic capacitors, which can be expected to be used (10° times), was considered. However, at present, the capacity of each piece is small,
Dozens of ceramic capacitors will be integrated in parallel, and a highly reliable one is required for practical use. .

An object of the present invention is to provide a method for improving the reliability of a capacitor bank in which a large number of ceramic capacitors are integrated.

[Means to solve the problem]

In order to achieve the above object, the present invention forms a capacitor bank by sandwiching a plurality of ceramic capacitors around parallel conductors, and circulates air or gas inside the capacitor bank to collect dust inside the bank. A dusting device was installed.

[Effect]

To stack multiple ceramic capacitors inside a capacitor bank, multiple ceramic capacitors are sandwiched between parallel conductor plates. Therefore, during charging, a strong electric field is generated between the conductor plates, and the dust inside the bank is charged. When charging and discharging are repeated, dust collects on the conductor plates due to the current collecting effect of the electric field, and there is a risk that the conductor plates will become bridged within an hour, causing a flashover. In the present invention, air or gas (for example, 5Fa) is circulated between parallel conductors to remove dust between the conductors.

This makes it possible to provide a capacitor bank with good withstand voltage reliability during frequent charging and discharging.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 2 shows an AB view of FIG.

Ceramic capacitor 4 is inside capacitor bank 1,
High voltage side conductor plate 3. It is provided in a sandwich-like manner between the low voltage side conductor plates 2. One of the conductor plates is connected via a coaxial cable 6 to a discharge switch 7 and via a transmission plate 19, 20 to a discharge tube 8. The capacitor bank 1 has a four-stage structure with partition plates 1a, and each conductor is insulated from the capacitor bank 1 with an insulator 5. 16 is an exposure mask, 17 is an exposure wafer, and 18 is an aligner. The discharge device 8 includes an exhaust device and an insulating spacer 13. It consists of electrodes 10.12.

In operation, power is supplied to the capacitor 4 from a charging power source (not shown) and charged to a predetermined voltage.Then, the discharge switch 7 is closed and the power is supplied to the pair of discharge devices 8 through the transmission plates 19 and 20. The above voltage is applied between the electrodes 10 and 12 to cause a discharge, and X-rays 14 are emitted due to the plasma pinch between the electrodes. The protective resistor 9 is provided in the discharge device 8 to absorb the energy of the capacitor 20 when no discharge occurs. The X-rays 14 are irradiated onto a resist-coated wafer 17 through an X-ray extraction window 15 and an X-ray mask 16, thereby exposing the wafer 17.

In this embodiment, in which a large number of ceramic capacitors are connected in parallel, high voltage reliability is the most important issue.

Normally, withstand voltage performance is required to be about 50 kV. Dust between the conductor plates 3 and 4 poses a particular problem in terms of high withstand voltage. For this purpose, an air circulator 21 and a filter 22 are provided inside the bank 1, and air is blown through an air duct 23. Dust between the conductor plates 3 and 4 is removed via the airflow deflection plate 24. This creates a strong electric field between the conductor plates when charging the capacitor.
When the dust inside the bank becomes electrically charged and is repeatedly charged and discharged (in general, the number of charging cycles is Looms and the number of discharge cycles is μs), the dust collects on the conductor plate due to the current collecting effect due to the electric field, which prevents flashover. There is. If a gas other than air, particularly an insulating gas SFe, is used as the gas to be blown, it can contribute to improving the withstand voltage inside the bank.

〔Effect of the invention〕

According to the present invention, a capacitor bank is constructed by sandwiching a plurality of ceramic capacitors between parallel conductor plates, and a device is installed to circulate air or an insulating gas within the capacitor bank and collect dust within the bank. This makes it possible to provide a capacitor bank with good withstand voltage reliability, which has the effect of improving the reliability of the plasma X-ray source.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 is an AB line diagram of FIG. 1. 1... Capacitor bank, 2... Low voltage side conductive plate, 3
...High voltage side conductor plate, 4...Ceramic capacitor,
5... Insulator, 21... Air circulator, 22... Filter, 23... Duct, 24... Air flow deflection plate. \ (Second
Figure 1≧7 2n

Claims (1)

[Claims] 1. In a plasma X-ray source consisting of a discharge device having at least one pair of electrodes provided in a vacuum container, an electric circuit for supplying a pulsed large current to the discharge device, and a capacitor bank, a plurality of capacitor banks are arranged on parallel conductor plates. 1. A plasma X-ray source characterized by connecting ceramic capacitors in a sandwich manner, circulating air or an insulating gas inside the capacitor bank, and providing a device for collecting dust inside the bank.