Gas separation: apparatus – Degasifying means for liquid – Sonic means
Reexamination Certificate
2000-10-24
2002-06-11
Smith, Duane S. (Department: 1724)
Gas separation: apparatus
Degasifying means for liquid
Sonic means
C096S193000, C096S219000
Reexamination Certificate
active
06402821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solution treatment unit which performs, for example, developing treatment on, for example, a substrate and a filter unit included in the solution treatment unit.
2. Description of the Related Art
A mask for forming a circuit pattern on the surface of a semiconductor wafer (described as a wafer hereinafter) is obtained by irradiating a resist face with light, an electron beam, an ion beam or the like and performing developing treatment thereon after coating the surface of the wafer with a resist. A developing step of these steps is to dissolve portions which are irradiated with light or the like, or portions which are not irradiated with the same in an exposing step, with an alkaline aqueous solution or the like, and is performed by a method shown in
FIG. 10
conventionally.
Namely, in a conventional method, a wafer w is adsorbed and held on a spin chuck
11
having a function of vacuum adsorption, and a supply nozzle
13
, in which a large number of discharge holes
12
are arranged over a length corresponding to a diameter of the wafer W, is positioned so that the discharge holes
12
are spaced, for example, 1 mm above the surface of the wafer W above the central portion of the wafer W. Further, a developing solution
10
is supplied through the discharge holes
12
to the central portion of the surface of the wafer W to perform coating thereof and the wafer is subsequently rotated a half turn (180 degree) while the developing solution
10
is supplied through the discharge holes
12
.
In a developing system of this type, as shown in
FIG. 11
, nitrogen (N
2
) gas is blown into a tank
14
, and the developing solution
10
is delivered with the pressure through a filter portion
15
and a valve
16
and so on, and supplied through the supply nozzle
13
to the wafer W.
The filter portion
15
is to remove, for example, particles or the like mixing into the developing solution
10
by filtering them, and has a structure in which a filter
101
for removing the particles or the like is provided to be connected with a flow path
102
for the developing solution inside of, for example, a case
100
, and further an exhaust passage
103
provided with a valve
104
is connected to the upper portion side of the flow path
102
.
105
is an electrical capacitance sensor for detecting the generation of bubbles, and
106
,
107
are supply flow paths for the developing solution
10
.
Incidentally, the pressure is applied to the inside of the tank
14
by the N
2
gas as described above in this supply system of the developing solution
10
, whereby the N
2
is dissolved in the developing solution
10
delivered with the application of pressure. Since a volume of the case
100
is larger than that of the supply flow path
106
for the developing solution
10
in the filter portion
15
, the developing solution
10
is under reduced pressure when flowing from the supply flow path
106
into the case
100
, and the N
2
dissolved in the developing solution
10
is vaporized to generate minute bubbles (micro bubbles) with the difference in pressure.
Due to such bubbles mixing into the developing solution
10
, the flow amount of the developing solution
10
varies by the amount of the bubbles present therein, the filtering precision of the filter
101
deteriorates due to the bubbles adhering thereto in the filter portion
15
, and an insufficient or no reaction occurs between the developing solution and a resist in portions in which the bubbles are mixing when the developing solution
10
is coated on the wafer W, thereby causing developing defects.
Conventionally, therefore, the bubbles generated in the filter portion
15
are removed together with the developing solution
10
through the exhaust passage
103
by manually opening the valve
104
. The electrical capacitance sensor
105
is set to be on when the amount of the bubbles increases equal to or greater than a standard value and set to be off when the amount of the bubbles is smaller than or equal to the standard value, and the opening and closing timing of the valve
104
is performed based on the on-off signal of the sensor
105
.
However, the above-described technique has disadvantages that the developing solution
10
containing the bubbles is exhausted together with the bubbles, thereby increasing the amount of the drained developing solution
10
and total consumption of the developing solution
10
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a filter unit and a solution treatment unit capable of reducing consumption of a treatment solution.
To achieve this object, in a filter unit according to the present invention for removing impurities and bubbles contained in a treatment solution comprising: an impurity filter for removing the impurities; a flow path for flowing the treatment solution into the impurity filter; an exhaust passage for exhausting gas to the outside of the filter unit, which is connected to the flow path; and a bubble filter provided inside of the exhaust passage or on a connecting portion between the exhaust passage and the flow path to block the exhaust passage, the bubble filter has a function of blocking transmission of liquid and transmitting gas, whereby the bubbles are removed from the treatment solution by making the bubbles contained in the treatment solution pass through the bubble filter. In such filter unit, only the bubbles can be removed from the treatment solution, whereby the treatment solution is not drained, enabling consumption of the treatment solution to be reduced.
It is preferable now to use a hollow fiber a membrane for the bubble filter, and in this case, the bubbles can be efficiently removed since a large contact area can be secured in a small volume in the hollow fiber membrane. Additionally, it may be structured that means for generating ultrasound is provided on the outside of the flow path, and dissolved gas contained in the treatment solution is forced to vaporize to generate the bubbles by giving ultrasonic vibration to the treatment solution flowing in the flow path, which makes it possible to remove also the dissolved gas, enabling the amount of the dissolved gas contained in the treatment solution to be further reduced.
Further, the filter unit may have a structure in which the flow path is formed in a ring shape so that the treatment solution flows from down upward therein, the impurity filter is provided on the inside of the flow path, and the exhaust passage is further provided on the upper portion side of the flow path, which enables the amount of the removed bubbles to be increased. Furthermore, a pressure in the exhaust passage may be lower than that of the flow path, which makes it possible to remove not only the bubbles contained in the treatment solution but also the dissolved gas, enabling the amount of the dissolved gas contained in the treatment solution to be reduced.
The solution treatment unit incorporating such filter unit is structured so that the treatment solution removed the impurities and the bubbles therefrom in the filter unit is supplied through a supply nozzle to the surface of a substrate held substantially horizontal by a substrate holding portion to form a treatment solution film on the surface of the substrate.
Moreover, a solution treatment unit according to the present, in which bubbles contained in a treatment solution from a treatment solution tank are removed in an intermediate tank, and the treatment solution is supplied through a supply nozzle to the surface of a substrate held substantially horizontal by a substrate holding portion to form a treatment solution film on the surface of the substrate, may be structured so that the intermediate tank comprises: an exhaust passage for exhausting gas to the outside of the intermediate tank; and a bubble filter provided inside of the exhaust passage or on a connecting portion between the exhaust passage and the flow path to block the exhaust passage, and the bubble filter h
Rader & Fishman & Grauer, PLLC
Smith Duane S.
Tokyo Electron Limited
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