Pumps – Combined
Reexamination Certificate
2001-09-21
2004-05-11
Look, Edward K. (Department: 3742)
Pumps
Combined
C417S053000
Reexamination Certificate
active
06733250
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a filter unit and a chemical liquid supply system and a chemical liquid supply method which are designed to predetermined amounts of a chemical liquid such as a photoresist solution.
BACKGROUND OF THE INVENTION
Chemical liquid such as a photoresist solution, a spinion glass solution, a polyimide resin solution, pure water, an etching solution, and an organic solution are used in manufacturing processes in various technical fields including a semiconductor wafer manufacturing technique, a liquid crystal substrate manufacturing technique, a magnetic disk manufacturing technique, and a multi-layered wiring board manufacturing technique. A chemical liquid supply system is used for coating with these chemicals.
For example, when a photoresist solution is to be coated on a surface of a semiconductor wafer, a predetermined amount of photoresist solution is dropped on the surface of the semiconductor wafer while the semiconductor wafer is rotated in a horizontal plane. In such a chemical liquid supply system, in order to deliver a chemical liquid such as a photoresist solution, a pump having a pump member formed of an elastically transformable tube or bellows as shown in Japanese Patent Laid-Open Publication No. 11-230048 or Japanese Patent Laid-Open Publication No. 10-61558 is used.
When a photoresist solution coated on a surface of a semiconductor wafer contains air bubbles or contaminants, a manufacturing yield of semiconductor integrated circuit devices decreases. For this reason, in a chemical liquid supply system used for a coating operation with such a photoresist solution, a filter is set to remove air bubbles and contaminants in the photoresist solution.
The filter is arranged on the primary side or secondary side of a pump, the degree of purity of a chemical liquid such as a photoresist solution is increased such that the chemical liquid passes through the filter by the delivery pressure of the pump. For this reason, contaminants are gradually adhered to the surface of the filter to cause clogging, and filters must be periodically exchanged. In this case, in recent years, filters are generally exchanged together with housings covering the filters.
In order to improve productivity, it is desired that a photoresist solution is continuously coated on a semiconductor wafer. For this reason, the coating operation must be designed to be performed when a photoresist solution stored in a solution tank is exhausted to exchange the solution tank for a new solution tank. Therefore, a buffer tank is arranged between a solution tank and the pump.
A chemical liquid flowed from the solution tank is filled in the buffer tank, and the pump is drawn through a pump inlet path connected to the bottom of the buffer tank. Therefore, when the solution tank is exchanged, or the solution tank is empty, the pump draws the chemical liquid in the buffer tank. For this reason, air bubbles cannot be prevented from being drawn into the pump. After completion of the exchange of solution tanks, the surface of the solution in the solution tank is pressured to fill the buffer bank with the chemical liquid so that air bubbles collected in the buffer tank are exhausted from an exhaust path.
In such a chemical liquid supply system, in order to improve the degree of purity of the chemical liquid it is important that a surface with which the chemical liquid is in contact, i.e., the contact surface of the solution is lowered in the flow path in the device. For this purpose, it is important that the configuration of the chemical liquid supply system is simplified.
SUMMARY OF THE INVENTION
However, in the chemical liquid supply system, since the filter is independent of the buffer tank, the flow path for connecting the filter and the buffer tank is required and an exhaust path for extracting air must be arranged in the filter and the buffer tank, respectively. Therefore, it is difficult to simplify the configuration of the chemical liquid supply system.
In addition, since the inner wall of the buffer tank is exposed to the air each time the solution tank is empty, a photoresist solution remaining on and adhered to the inner wall is hardened or gelled to be contaminants, and the contaminants may be mixed with a newly supplied photoresist solution. These contaminants cannot be easily filtered by a filter. Furthermore, since the buffer tank is structured such that the buffer tank cannot be easily exchanged because of the function of the buffer tank, it is difficult to remove the deteriorated photoresist solution generated from the inner surface of the buffer tank. For this reason, the yield of products is decreased.
It is an object of the present invention to coat a chemical liquid having a high degree of purity.
According to the present invention, there is provided a filter unit including a filter vessel in which a filter material housing chamber and a solution storage chamber for storing a chemical liquid are arranged, the filter material housing chamber having a bottom wall portion, a side wall portion, and an upper wall portion and having a filter material incorporated therein, a solution inflow port arranged on the filter vessel to communicate with the solution storage chamber; a solution outflow port, arranged on the filter vessel, for guiding a solution filtered by the filter material, and an exhaust port, arranged on the filter vessel to communicate with the solution storage chamber, for exhausting a gas in the solution storage chamber.
In the filter unit according to the present invention, the filter vessel supports the filter material and has an adaptor for partitioning the filter vessel into a lower filter material housing chamber and an upper solution storage chamber, and the adaptor has a filtered solution guide path for guiding a filtered solution to the solution outflow port.
In the filter unit according to the present invention, the filter vessel has a partition wall for partitioning the filter vessel into the solution storage chamber and the filter material housing chamber, and a communication hole for causing the solution storage chamber and the filter material housing chamber to communicate with each other is formed in a lower end portion of the partition wall.
The filter unit according to the present invention has an exhaust port arranged on the filter vessel to communicate with the filter material housing chamber.
The filter unit according to the present invention has solution level detection means for detecting a solution level of the chemical liquid in the solution storage chamber.
According to the present invention, there is provided a chemical liquid supply system including a pump and a solution inflow port, the pump having a solution delivery port to which a solution delivery path having a delivery nozzle arranged thereon is connected, a filter vessel in which a filter housing chamber having a filter material incorporated therein and a solution storage chamber for storing a chemical liquid are arranged, a solution inflow port to which a solution guide path connected to a solution tank is connected and which is formed on the filter vessel to communicate with the solution storage chamber, a solution outflow port which is formed on the filter vessel and to which a pump inlet path connected to the solution inflow port is connected, and an exhaust port, which is formed on the filter vessel to communicate the solution storage chamber, for exhausting a gas in the solution storage chamber.
In the chemical liquid supply system according to the present invention, the filter vessel is integrated with the pump.
In the chemical liquid supply system according to the present invention, a return path for connecting the pump to the solution storage chamber is arranged, and the chemical liquid and the gas in the pump can be moved to the solution storage chamber.
According to the present invention, there is provided a chemical liquid supply system including a filter vessel in which a filter material housing chamber having a filter material incorpo
Koganei Corporation
Look Edward K.
McCormick Paulding & Huber LLP
Patel Vinod D.
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