Dielectric barrier discharge lamp and dry cleaning device...

Details Dielectric barrier discharge lamp and dry cleaning device... Dielectric barrier discharge lamp and dry cleaning device...

2000-12-29

2003-09-30

Patidar, Jay (Department: 2862)

Electric lamp and discharge devices

With gas or vapor

Having electrode exterior to envelope

C313S234000, C313S634000, C313S493000

Reexamination Certificate

active

06628078

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a double-cylinder type dielectric barrier discharge lamp and a dry cleaning device which uses a dielectric barrier discharge lamp as the ultraviolet light source, and particularly for dry cleaning device, relates to a dry cleaning device with which the organic substances adhering to the surface of a workpiece, such as a semiconductor wafer, are decomposed by projecting the ultraviolet light itself or exposing the workpiece to the ozone generated with the ultraviolet light.
2. Description of the Prior Art
The dry cleaning device with which ultraviolet light is projected onto a workpiece, such as a semiconductor wafer, or the workpiece is exposed to the ozone generated when the ultraviolet light permeates the air or gas oxygen, for decomposing and removing the organic substances adhering to the surface of the workpiece has been conventionally used in the semiconductor manufacturing process and the like. Some dry cleaning devices use not only either ultraviolet light or ozone, but also both ultraviolet light and ozone for promotion of decomposition of the organic substances.
As an ultraviolet light source for use with a dry cleaning device, a variety of discharge lamps, such as a mercury lamp, are widely known. Being a type of discharge lamp, the dielectric barrier discharge lamp which uses xenon as the principal component of the discharge gas radiates ultraviolet light having a wavelength as short as 172 nm. The ultraviolet light with a short wavelength has high power, being excellent in ability to decompose an organic substance, and thus can be advantageously used as cleaning power for a dry cleaning device, therefore, the dielectric barrier discharge lamp is excellent as the ultraviolet light source for a dry cleaning device.
The dielectric barrier discharge lamp is described in Japanese Unexamined Patent Publication No. 7(1995)-272693, for example. The cleaning device which uses a dielectric barrier discharge lamp as the ultraviolet light source is disclosed in Japanese Patent Publication No. 2705023, for example. In
FIG. 11
in this Japanese Patent Publication No. 2705023, a tabular light source device is shown as the ultraviolet light source for a dry cleaning device. With the tabular light source device as shown in
FIG. 11
in Japanese Patent Publication No. 2705023, double-cylinder type dielectric barrier discharge lamps (
33
a,
33
b,
33
c
) are disposed side by side in the recess (
4
) of a lunch-box type metallic container (
30
) which also serve as a light reflecting plate. The metallic container (
30
) is of tabular type, one wide surface being provided as an open surface. The open surface is covered with a light taking-out window (
31
) made of a synthetic quartz glass plate. Into the recess (
4
) of the metallic container (
30
), nitrogen (N
2
) gas is fed at a rate of a few liters per minute. In the air, ultraviolet light is contacted with oxygen, and converts it into ozone, therefore, by filling the recess (
4
) with nitrogen (N
2
) gas in place of air, attenuation of the ultraviolet light and generation of ozone in the metallic container (
30
) are prevented. With this double-cylinder type dielectric barrier discharge lamp (
33
a,
33
b,
33
c
), a net-like outside electrode (
20
a,
20
b,
20
c
) is exposed, therefore, if ozone is generated in the recess (
4
), the outside electrode (
20
a,
20
b,
20
c
) will be oxidized, and deteriorated, but by filling the recess (
4
) with nitrogen (N
2
) gas, generation of ozone is prevented, and thus deterioration of the outside electrode (
20
a,
20
b,
20
c
) is suppressed.
The tabular light source device as shown in
FIG. 11
in the above-mentioned Japanese Patent Publication No. 2705023 is used as the ultraviolet light source (
100
) for the dry cleaning device as shown in
FIG. 2
in the same Japanese Patent Publication or the like. With the dry cleaning device as shown in
FIG. 2
in Japanese Patent Publication No. 2705023, the ultraviolet light source (
100
) and a substance to be treated (a substance from which the organic contamination adhering to the surface is removed, being oxidized by the ultraviolet light or ozone, i.e., a workpiece, which is here a slide glass (
9
)) are disposed in a treatment chamber (
7
). The ultraviolet light source (
100
) is held at a level of “d” above the top of the workpiece (
9
). Into the treatment chamber (
7
), a gas mixture of nitrogen (N
2
) gas and oxygen (O
2
) gas are supplied. The ultraviolet light radiated from the dielectric barrier discharge lamp permeates the nitrogen (N
2
) gas in the ultraviolet light source (
100
), further permeates the quartz glass of the taking-out window in the ultraviolet light source (
100
), and permeates the gas mixture of nitrogen (N
2
) gas and oxygen (O
2
) gas in the treatment chamber (
7
), being projected onto the top of the workpiece (
9
). Ozone offers a strong oxidation action, thus is used in conjunction with the ultraviolet light for cleaning the workpiece (
9
).
In
FIG. 7
in the above-mentioned Japanese Patent Publication No. 2705023, an example of double-cylinder type dielectric barrier discharge lamp is given in detail. The discharge lamp (
18
) in this double-cylinder type dielectric barrier discharge lamp is made of quartz glass, and is in the shape of a hollow cylinder, an inner tube (
23
) and an outer tube (
24
) being provided coaxially. A metallic electrode (
20
), which is the outside electrode, is provided on the outer surface of the outer tube (
24
), being formed in a net-like shape to allow permeation of the light. The outside electrode (
20
) is coated with an antioxidizing coating (
22
). An electrode (
19
), which is the inside electrode, comprises an aluminum film formed on the outer surface (the circumferential wall) of the inner tube (
23
), which also serves a reflection coating. The space between the inner tube (
23
) and the outer tube (
24
) provides a discharge space (
21
), which is filled with xenon as a discharge gas. The discharge container (
18
) has an overall length of 100 mm with the inner tube (
23
) having an outside diameter of 6 mm, and the outer tube (
24
) having an inside diameter of 8 mm.
FIG. 7
in Japanese Unexamined Patent Publication No. 7(1995)-272693 gives another example of dielectric barrier discharge lamp. The dielectric barrier discharge lamp as shown in
FIG. 7
in Japanese Unexamined Patent Publication No. 7(1995)-272693 is called an aperture type one, having an outside electrode (
8
) made of aluminum which also serves as a light reflecting plate, being provided on a part of the circumferential surface of a discharge container (
1
). The region of the discharge container (
1
) which has no outside electrode provides a light taking-out window (
9
). The light taking-out window (
9
) extends in the longitudinal direction of the lamp, being formed in a slit-like shape.
To dissipate the heat generated in the dielectric barrier discharge lamp, air cooling by means of a fan and water cooling by passing the water through the cooling water tube provided inside of the discharge container.
However, providing a cooling fan or a cooling water supply device separately results in a complicated, large-sized, and expensive lamp device as an ultraviolet light source, making the maintenance cumbersome, and lowering the reliability.
A dielectric barrier discharge lamp must be provided with a means for preventing the electrode from being oxidized by the ozone generated by the ultraviolet light acting on the oxygen (O
2
) gas. With the dielectric barrier discharge lamp as shown in
FIG. 7
in the above-mentioned Japanese Patent Publication No. 2705023, the outside electrode (
20
) is coated with an anti-oxidizing coating (
22
). Further, with the tabular light source device as shown in
FIG. 11
in the same Japanese Patent Publication, the dielectric barrier discharge lamp is housed in the chamber filled with nitrogen (N
2
) gas. But, with the aperture type dielectric barrier discharge lamp as shown in

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