Drying and gas or vapor contact with solids – Apparatus – Sheet – web – or strand
Reexamination Certificate
2000-05-25
2001-11-27
Walberg, Teresa (Department: 3742)
Drying and gas or vapor contact with solids
Apparatus
Sheet, web, or strand
C034S638000, C034S448000
Reexamination Certificate
active
06321463
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a substrate treating apparatus suitable for cleaning and drying substrates having low mechanical strength, e.g. glass substrates and semiconductor wafers, and also relates to a method of operating the substrate treating apparatus.
Drying techniques carried out after the process of cleaning semiconductor wafers, optical discs, etc. can be generally divided into two types as follows. A first type is a technique that employs chemicals, e.g. IPA (isopropyl alcohol). A second type is a technique whereby an object to be dried is rotated at high speed to blow off droplets under centrifugal force. In addition, techniques in which a vacuum technique is combined with the first or second techniques are also employed. However, these techniques suffer from the problems stated below.
The drying method using chemicals, e.g. IPA, incurs a high costs to ensure safety as combustible chemicals are employed. Moreover, this method is liable to cause environmental pollution.
In the drying method using high-speed rotation, because an object to be dried is rotated at high speed, a centrifugal force acts on the object, and torsional stress also acts thereon during acceleration or deceleration of the rotation, causing the base material of the object to be damaged. This causes a reduction in yield. In addition, during the drying process, the base material of a substrate to be treated elutes out into contact areas between the substrate and waterdrops to form annular protuberance-shaped traces, i.e. water marks.
It has been proposed to dry a substrate by using an apparatus shown in
FIG. 1. A
substrate
101
to be treated (i.e. an object to be dried) is placed in a stationary state, a rotary impeller
102
is installed to face a surface of the substrate
101
and the surface of the substrate
101
is dried by rotation of the rotary impeller
102
. However, this proposal has not yet been put to practical use for the following reason. That is, an outward air flow occurring on the surface of the impeller
102
produces a negative pressure at the central portion of the rotary impeller
102
. Consequently, a secondary flow occurs on the surface of the substrate
101
as shown by the arrow A. As a result, a waterdrop
103
is likely to remain in the center of the surface of the substrate
101
.
In addition, a rotating shaft
105
of a motor
104
for rotating the rotary impeller
102
is supported by rolling bearings
106
and
107
. Therefore, if lubrication is effected with a grease which is usable in a clean environment, the upper limit value for the DN value [bearing diameter (mm)×rotational speed (rpm)] is low, so that it is difficult to employ a rotating shaft
105
in the form of a hollow shaft.
SUMMARY OF THE INVENTION
In view of the above-described circumstances, an object of the present invention is to provide a substrate treating apparatus which is capable of rapidly cleaning and drying a surface of a substrate to be treated without damaging the base material of the substrate and without forming any water mark on the surface of the substrate, and which does not generate particles or the like and is therefore capable of maintaining clean conditions, and also to provide a method of operating the substrate treating apparatus.
To solve the above-described problems, according to a first aspect of the invention, a substrate treating apparatus is provided which includes a substrate support mechanism for supporting a substrate to be treated, and a rotary impeller placed to face a surface of the substrate supported by the substrate support mechanism. At least one nozzle is provided in an approximately central portion of the rotary impeller. Rotating the rotary impeller produces a flow of gas passing through the nozzle and flowing from the central portion of the impeller toward the outer periphery thereof, thereby drying the surface of the substrate supported in a stationary state by the substrate support mechanism.
As stated above, rotating the rotary impeller causes a gas flow expelled through the nozzle provided in the central portion of the rotary impeller to form a flow along the surface of a substrate which is supported in a stationary state by the substrate support mechanism. Thus, the gas flows toward the outer periphery of the substrate, enabling the substrate surface to be dried efficiently. Moreover, the rotation of the rotary impeller causes the gas to flow into the gap between the rotary impeller and the substrate through the nozzle. Therefore, no negative pressure is produced at the central portion of the impeller. Accordingly, no waterdrops remain on the central portion of the surface of the substrate, and the substrate surface can be dried rapidly. In addition, since the substrate is held stationary, no stress acts thereon.
According to a second aspect of the invention, in the substrate treating apparatus according to the first aspect, the rotary impeller is secured to a hollow rotating shaft. The hollow section of the rotating shaft communicates with the nozzle. The hollow section is provided with either or both of a pure water supply port for supplying pure water and a clean gas supply port for supplying a clean gas.
Because either or both of a pure water supply port and a clean gas supply port are provided in the hollow section of the rotating shaft, as stated above, pure water and/or a clean gas can be supplied to the central portion of the substrate through the nozzle. This arrangement is suitable for cleaning and drying a substrate as will be described later in detail.
According to a third aspect of the invention, in the substrate treating apparatus according to the first or second aspect, the rotary impeller is connected to a rotating shaft of a driving motor. The rotating shaft of the driving motor is supported by a magnetic bearing.
Because the rotating shaft of the driving motor is supported by magnetic levitation manner by a magnetic bearing, as stated above, there is no likelihood of particles being generated. Thus, the apparatus can be used in a clean environment.
According to a fourth aspect of the invention, in the substrate treating apparatus according to any one of the first to third aspects, a surface of the rotary impeller that faces the substrate is a flat surface.
If the surface of the rotary impeller that faces the substrate is flat, as stated above, although the blade efficiency is reduced to a some extent, the surface of the rotary impeller that faces the substrate can be brought as close to the substrate as possible, and an outward gas flow can be produced at a position extremely close to the surface of the substrate. Therefore, the substrate surface can be dried efficiently.
According to a fifth aspect of the invention, in the substrate treating apparatus according to any one of the first to fourth aspects, the rotary impeller has a flat surface extending from the center thereof to a position slightly outside the outer periphery of the substrate and further has a blade structure outside the flat surface.
If the rotary impeller has a flat surface extending from the center thereof to a position slightly outside the outer periphery of the substrate and further has a blade structure outside the flat surface, as stated above, the flat surface can be placed in close proximity to the substrate. The gas from the nozzle in the central portion of the impeller flows from the central portion toward the outer periphery close to the surface of the substrate in such a manner as to be sucked into the blade structure outside the flat surface. Accordingly, the substrate can be dried more efficiently by the increased gas flow.
According to a sixth aspect of the invention, a method of operating a substrate treating apparatus is provided, wherein the substrate treating apparatus includes a substrate support mechanism for supporting a substrate to be treated, and a rotary impeller secured to a hollow rotating shaft and positioned so as to face a surface of the substrate supported by the substrate support mechanis
Ebara Corporation
Fastovsky Loenid M
Walberg Teresa
Wenderoth, Lind & Ponack L.L.P
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