Illumination – Light source and modifier – Ionized gas or vapor light source
Reexamination Certificate
2000-11-24
2002-04-30
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
Ionized gas or vapor light source
C313S113000, C313S607000, C313S234000
Reexamination Certificate
active
06379024
ABSTRACT:
TECHNICAL BACKGROUND
1. Field of the Invention
The present invention relates to a dielectric barrier excimer lamp and an ultraviolet light beam irradiating apparatus to which the dielectric barrier excimer lamp is applied. More specifically, the present invention relates to a dielectric barrier excimer lamp for cleaning or modifying the surface of a semiconductor wafer or a glass substrate by means of joint activities of ultraviolet light beam and ozone, and an ultraviolet light beam irradiating apparatus having the dielectric barrier excimer lamp.
2. Related Art Statement
In recent years, studies are being widely made with regard to a method for cleaning or modifying a work such as a metal, a semiconductor substance or a glass by means of the joint activities of ultraviolet light beam and ozone. The above method is generally known as a UV ozone method. The UV ozone method has advantages that an organic contaminant adhering to a work surface can be removed, and that an oxide film can be formed on the surface, without damaging the work.
In the UV ozone method, air containing oxygen or oxygen gas is irradiated with 185 nm light that is a vacuum ultraviolet light beam radiated from a low-pressure mercury lamp, whereby ozone is generated. Active oxygen species that is a decomposed gas from ozone is generated from the ozone and brought into contact with a work surface. In cleaning the work by the UV ozone method, an organic contaminant adhering to the work surface is oxidized upon contact with the active oxygen species and converted to low-molecular oxides such as carbon dioxide and water, whereby it is removed from the surface. In this manner, the work surface can be finely dry-cleaned.
A low-pressure mercury lamp has greatly contributed to wide use of the above UV ozone cleaning due to its characteristic emitted light beam, and in recent years, a dielectric barrier excimer lamp has come to be known as a light source capable of providing more efficient cleaning and is replacing the conventional low-pressure mercury lamp as a light source for the UV ozone cleaning. The dielectric barrier excimer lamp has advantages that it overcomes the problems of heat radiation to a substrate, lighting performance, etc., which have been defects of the low-pressure mercury lamp, further that it has an emitted light beam having a shorter wavelength so that it is excellent in breaking an organic compound and that it can more efficiently generate active oxygen.
FIG. 13
shows one constitution of a conventional dielectric barrier excimer lamp unit. As shown in
FIG. 13
, a lamp unit
40
has an excimer lamp
42
inside a metal container
41
. The excimer lamp
42
has an inner cylindrical tube
42
a
and an outer cylindrical tube
42
b
both made of quartz glass and has a discharge gas
43
such as xenon gas charged in a space between these tubes. And, a high voltage is applied between electrodes
42
c
and
42
d
provided inside and outside the tubes (the electrode on the outside thereof has the form of a network) from an alternate current power source (not shown), whereby the excimer lamp
42
radiates ultraviolet light. That is, upon application of the high voltage, the quartz glass that is a dielectric material generates a microdischarge due to dielectric barrier discharge (silent discharge), to excite and combine the discharge gas
43
charged inside with the energy of the microdischarge, and the gas molecules in an excited state radiate light beam having a wavelength characteristic of the gas in the process of the gas molecules restoring their ground state.
The metal container
41
of the lamp unit
40
has a light window
44
made of a synthetic quartz glass, and an ultraviolet light beam radiated from the excimer lamp
42
is transmitted through it and a work is irradiated therewith. In the metal container
41
, an inert gas such as nitrogen gas is constantly flowed at a rate of several liters per minute, so that the attenuation of the ultraviolet light beam from the excimer lamp
42
controlled to make it as small as possible. Further, the metal container
41
internally has a reflection plate
45
(or the inner wall surface of the metal container is mirror-processed), whereby an ultraviolet light beam radiated upward and sideward from the excimer lamp
42
is reflected thereon and led toward the light window
44
. The ultraviolet light beam which comes out of the container through the light window
44
generates ozone and active oxygen species due to its photochemical reaction in an oxygen-containing atmosphere where a work is placed, to bring them into contact with the surface of the work, and further, the work is irradiated directly with this vacuum ultraviolet light beam, so that the cleaning and modification of the work is attained by co-working of these.
However, the above conventional dielectric barrier excimer lamp unit has the following problems.
(1) Ultraviolet light beam radiated upward and sideward from excimer lamp
42
is reflected on the reflection plate
45
and lead toward the light window
44
. However, the reaching efficiency thereof is very low, and most of the above ultraviolet light beam radiated upward comes to nothing. The radiation efficiency of ultraviolet light beam based on power inputted to the excimer lamp
42
is very poor.
(2) The synthetic quartz used as a material for the above light window
44
is expensive and increases the cost of the unit. Particularly in a unit in which a plurality of the excimer lamps
42
are provided in the metal container
41
for broadening the irradiation region of the ultraviolet light beam, the light window
44
has a large area, which causes a serious cost problem.
(3) The above light window
44
made of the synthetic quartz causes so-called solarization which is a phenomenon that a color center is generated with slight impurities such as iron and manganese due to irradiation with ultraviolet light beam and blackening takes place. The transmitted-light quantity is attenuated due to the solarization, and as a result, the cleaning effect decreases.
(4) The inert gas such as nitrogen that is flowed into the metal container
41
is effective for decreasing absorption of ultraviolet light beam in the container. On the other hand, it requires an additional cost, and handling thereof requires labors in view of environmental protection.
(5) The outer electrode
42
d
is exposed on the outer circumference of the excimer lamp
42
, so that it is required to take care when the excimer lamp
42
is attached inside the metal container
41
. For this reason, the position of the excimer lamp
42
relative to the container is liable to vary when the excimer lamp
42
is attached, and the variability may influence the irradiation performance of the unit.
(6) The above metal container
41
has a relatively large space around the excimer lamp
42
for disposing the above reflection plate and attaching the excimer lamp
42
. It is therefore required to constantly flow the inert gas necessary for filling the space with it at a rate of approximately several liters per minute, so that the consumption thereof comes to be very large.
(7) For improving the efficiency of cleaning or modifying the work with ultraviolet light beam, preferably, the distance between the surface of the excimer lamp
42
and the work is shortened so as to make it as small as possible, and the ultraviolet light beam is increased in radiation light quantity. In the conventional lamp unit, however, it is difficult to shorten the above distance due to its structure in which the excimer lamp is housed in the metal container.
SUMMARY OF THE INVENTION
Under the circumstances, it is a first object of the present invention to provide a dielectric barrier excimer lamp which can be improved in ultraviolet light beam radiation efficiency relative to power inputted to the excimer lamp and ultraviolet light beam irradiation efficiency to a work, which is easy to handle and less expensive and which attains the performance of a low running cost.
It is a second object of the present invention
Amano Satoru
Hiratsuka Katsumi
Kobayashi Norio
Kogure Yasuo
Hoya-Schott Corporation
Nixon & Vanderhye
O'Shea Sandra
Sawhney Hargobind S.
LandOfFree
Dielectric barrier excimer lamp and ultraviolet light beam... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dielectric barrier excimer lamp and ultraviolet light beam..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric barrier excimer lamp and ultraviolet light beam... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2918307