Radiant energy – Irradiation of objects or material
Reexamination Certificate
1999-11-23
2002-01-29
Anderson, Bruce (Department: 2881)
Radiant energy
Irradiation of objects or material
C250S492230, C250S492220, C250S50400H
Reexamination Certificate
active
06342702
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an ultraviolet ray irradiation apparatus by the use of a dielectric barrier discharge lamp (may be referred to as an excimer lamp) which washes and modifies a surface of semiconductor, metal, or macromolecular compound and the like.
The dielectric barrier discharge lamp (excimer lamp) has different wavelength with respect to emitted light beams in accordance with the kinds of gases sealed in a lamp tube. For example, a light beam having center wavelength of 172 nm, 222 nm and 308 nm is emitted when a sealed gas is xenon, krypton chloride, and xenon chloride, respectively.
In particular, the dielectric barrier discharge lamp sealed with the xenon emits a light beam having wavelength of 172 nm as a vacuum ultraviolet light beam. To this end, when irradiation is carried out in atmosphere containing oxygen, oxygen molecular (O
2
) absorbs the light beam, and generates active oxygen species, such as, oxygen atom (O) and ozone (O
3
).
Further, photon energy of a light beam having wavelength of 172 nm is about 7.2 eV, and is higher than combination energy of a plurality of organic substances. In consequence, chemical bonds of organic compound can be cut by irradiating the light beam of 172 nm, and oxidation decomposition removal can be performed by the generated active oxygen species.
This method has been known as an UV ozone cleaning method, and been widely applied in a manufacturing process of a semiconductor integrated circuit or liquid crystal as an organic substance washing method. Further, practical use has been proceeded as a method for removing metal contamination about a method for generating chlorine radical by irradiating the ultraviolet light beam to chlorine gas, for generating chloride by reacting the chlorine radical with metal attached to a substrate surface, and for volatilizing and removing by utilizing difference of vaporizing pressure, or a method for irradiating the ultraviolet light beam to gas containing fluorine and for removing a natural oxide film on a silicon wafer by the generated fluorine radical.
The semiconductor integrated circuit is increased in its integration every year, and a permitted level of the organic compound contamination is also enhanced in a manufacturing process of the integrated circuit. Recently, the silicon wafer as the substrate of the integrated circuit mainly has a diameter of 200 mm, and a diameter of 300 mm has been gradually applied.
When the dielectric barrier discharge lamp is used to remove the organic substance contamination, a plurality of dielectric barrier discharge lamps must be arranged so as to irradiate the light beam into substrates having these sizes. For example, an apparatus, in which a plurality of lamps
120
having a length of 230 mm are used with desired spaces, has been commercially used as the ultraviolet ray irradiation apparatus for the silicon wafer having the diameter of 200 mm, as illustrated in FIG.
1
A and FIG.
1
B. In the ultraviolet ray irradiation apparatus of such a surface irradiating block system, as a size of a substance to be processed and be irradiated is larger, the number of the lamps is higher from necessity for irradiating the light beam throughout the substance to be processed.
However, when the number of the lamps is plural as an example illustrated in
FIG. 1
, it is necessary to replace old lamps due to the lamps' lifetime with a required number of new lamps.
Further, if a plurality of lamps are used, the same number of lamp driving (lightning) circuits are required, and cost thereof becomes excessively high. Moreover, looking at plural lamps in terms of uniformity of irradiation, intensity of irradiated light beams differs directly under the lamps and in-between the lamps. Therefore, even if a reflection mirror is provided, nonuniformity of light quantity inevitably takes place for the light beam irradiated into the substance to be processed.
There is a method for performing irradiation by lineally scanning the substance to be processed or the dielectric barrier discharge lamp by the use of a single dielectric barrier discharge lamp as means for solving such a problem. The cost for the replacement due to the lamp lifetime can be reduced in this method because only single dielectric barrier discharge lamp is used. In addition, the light quantity of the light beam irradiated into the substance to be processed can be uniform because the single lamp is lineally scanned.
However, the ultraviolet light beam must be irradiated for an entire region of the substance to be processed in the method for lineally scanning the substance or the lamp. Consequently, a distance for scanning them must be equal or more to the diameter of the substance to be processed.
Further, a supporting mechanism, such as, a guide rail, becomes necessary at both sides thereof because the dielectric barrier discharge lamp is lineally scanned. As a result, the apparatus becomes large and expensive.
Moreover, it is difficult to tightly cover between the dielectric barrier discharge lamp and the substance to be processed, and is difficult to use corrosive gas, such as, chlorine gas and fluorine gas.
Due to the above-mentioned reasons, suggestion has been made about an apparatus in which the substance to be processed is rotatably supported on a supporting stand, and a process is carried out by relatively rotating the substance for the dielectric barrier discharge lamp (for example, see Japanese Unexamined Patent Publication (JP-A) No. H09-92634).
An apparatus structure can be simplified in the conventional apparatus in comparison with the case that the dielectric barrier discharge lamp is lineally scanned. Thereby, downsizing of the apparatus becomes possible.
On the other hand, when the ultraviolet light beam is given for the substance to be processed by rotating the irradiating range, a relative speed between the substance and the lamp is variable in accordance with a distance from the rotating center. Therefore, when irradiating light quantity for a length direction of the dielectric barrier discharge lamp is constant, as the distance from the rotating center becomes larger, the integrating light quantity for the surface of the substance becomes smaller. As a result, the surface process can not be uniformly carried out.
To solve this problem, a light shielding plate, in which a region (hereinafter, referred to as an ultraviolet light passing region) for passing the ultraviolet light beam of substantially triangle shape is formed, is arranged in a method described in FIG.
5
and description in the above-mentioned Japanese Unexamined Patent Publication (JP-A) No. H09-92634. Thereby, the integrating light quantity of the ultraviolet light beam, which reaches the surface of the substance to be processed, is adjusted in accordance with the distance from the rotating center.
However, when the irradiation of the ultraviolet light beam is performed through the above-mentioned ultraviolet light passing region of the triangle shape, it has been confirmed by inventor's experiment that the integrating light quantity on the surface of the substance to be processed does not accurately become constant in accordance with the distance from the rotating center.
This is because the light intensity for width direction of the dielectric barrier discharge lamp
11
distributes to an angled shape, and is not constant, as illustrated in FIG.
4
A. In the experiment, such a result that the integrating light quantity becomes smaller in accordance with the distance from the rotating center has been obtained. From this fact, when the shielding plate of the triangle shape is used, the uniform surface process can not be performed.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an ultraviolet ray irradiation apparatus which is capable of approaching integrating light quantity of an ultraviolet light beam for a surface of a substance to be processed constant when an ultraviolet light beam is irradiated by relatively rotating the substance for a dielectr
Amano Satoru
Jinbo Yosuke
Anderson Bruce
Hoya-Schott Corporation
Quash Anthony
LandOfFree
Ultraviolet ray irradiation apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ultraviolet ray irradiation apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultraviolet ray irradiation apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2869906