Coating apparatus – Projection or spray type
Reexamination Certificate
2001-10-10
2004-06-22
Crispino, Richard (Department: 1734)
Coating apparatus
Projection or spray type
C118S052000, C118S320000, C118S326000, C118S500000, C118S061000, C118S064000
Reexamination Certificate
active
06752872
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coating unit and a coating method for a substrate.
2. Description of the Related Art
In a photolithography process, for example, in semiconductor device fabrication processes, resist coating treatment for applying a resist solution on a surface of a substrate, for example, a semiconductor wafer (hereinafter referred to as a ‘wafer’), to form a resist film, exposure processing for exposing the wafer in a pattern, developing treatment for developing the wafer after being exposed in the pattern, and so on are performed to form a predetermined circuit pattern on the wafer.
The above resist coating treatment is usually performed in a resist coating unit, and for example, a cylindrical cup with an upper part thereof being open is provided inside a casing of the resist coating unit and a spin chuck for holding the wafer by suction to rotate the wafer is provided inside the cup. The resist coating treatment for the wafer is performed in a manner in which the rotated wafer is supplied with the resist solution onto the center thereof, the resist solution on the wafer is diffused by a centrifugal force which is caused by the rotation, and a uniform resist film is formed on the wafer.
Furthermore, atmospheres inside the casing and the cup need to be maintained at predetermined temperature and humidity when the resist coating treatment is performed. For this purpose, a supply device for supplying gas such as air and inert gas to the wafer inside the cup and an exhaust device for exhausting the atmosphere inside the cup from a bottom portion of the cup are provided in the resist coating unit. Conventionally, only this exhaust device is provided as an exhaust device for exhausting an atmosphere inside the resist coating unit and an amount of the gas supplied by the supply device and an amount of the atmosphere exhausted by the exhaust device are adjusted to maintain a processing environment of the resist coating treatment.
However, since film thickness of the resist film varies depending on a flow speed when the above-mentioned gas is supplied, it is necessary to maintain the flow speed of the gas within a predetermined range and it is also necessary to maintain a pressure inside the casing at a positive pressure in order to prevent impurities from the outside of the casing from flowing into the casing while maintaining a flow rate of the above-mentioned exhausted gas at a certain level or higher in order to prevent impurities produced from the wafer from flowing out of the cup. Therefore, it is very difficult to adjust each of the exhaust flow rates and the flow rate of the supplied gas with only one exhaust device and the supply device as described above to satisfy all of the above conditions.
SUMMARY OF THE INVENTION
The present invention is made in consideration of the above-described aspects, and its object is to provide a coating unit and a coating method capable of further facilitating atmosphere control in a casing and a cup.
In order to achieve the above object, a coating unit according to the present invention is a coating unit for applying a coating solution on a substrate, comprising: a container enclosing the substrate; a casing for accommodating the container therein; a supply device for supplying a predetermined gas into the casing; a first exhaust pipe for exhausting an atmosphere inside the container; a second exhaust pipe for exhausting an atmosphere inside the casing; a first adjusting device which is disposed in the first exhaust pipe, for adjusting a flow rate of an atmosphere passing through the first exhaust pipe; and a second adjusting device which is disposed in the second exhaust pipe, for adjusting a flow rate of an atmosphere passing through the second exhaust pipe.
A coating method according to the present invention is a coating method for applying a coating solution on a substrate, wherein utilized is a coating unit comprising: a container enclosing the substrate; a casing for accommodating the container therein; a supply device for supplying a predetermined gas into the casing; a first exhaust pipe for exhausting an atmosphere inside the container; a second exhaust pipe for exhausting an atmosphere inside the casing; a first adjusting device which is disposed in the first exhaust pipe, for adjusting a flow rate of an atmosphere passing through the first exhaust pipe; and a second adjusting device which is disposed in the second exhaust pipe, for adjusting a flow rate of an atmosphere passing through the second exhaust pipe, and the coating method comprising the step of adjusting a flow rate of the atmosphere inside the casing which is exhausted from the second exhaust pipe to maintain a pressure inside the casing at a higher level than a pressure outside the casing.
According to the present invention, the second exhaust pipe for exhausting the atmosphere inside the casing is provided separately in addition to the first exhaust pipe for exhausting the atmosphere inside the container so that the exhaust flow rate can be adjusted by the second exhaust pipe to maintain the pressure inside the casing at a positive pressure. This makes it possible to divide, with the use of the first exhaust pipe and the second exhaust pipe, the work which satisfies the conditions of exhausting the atmosphere inside the casing to maintain the pressure inside the casing at the positive pressure relative to the amount of the supplied gas and exhausting the atmosphere inside the container at a predetermined flow rate or higher to prevent the atmosphere inside the container from flowing out of the container as described above. Consequently, the atmospheres inside the casing and the container can be controlled more easily.
According to the present invention, the use of the second exhaust pipe for maintaining the pressure inside the casing at the positive pressure makes it possible to have the works of adjusting the exhaust flow rate of the atmosphere inside the container and adjusting the positive pressure inside the casing, which are conventionally carried out by one exhaust pipe, performed separately by different exhaust pipes to facilitate each of the adjustments.
REFERENCES:
patent: 5472502 (1995-12-01), Batchelder
patent: 5565034 (1996-10-01), Nanbu et al.
patent: 5672205 (1997-09-01), Fujimoto et al.
patent: 5690995 (1997-11-01), Fischli et al.
patent: 6159541 (2000-12-01), Sakai et al.
patent: 6333003 (2001-12-01), Katano et al.
Hayashi Shin'ichi
Inada Hiroichi
Crispino Richard
Lazor Michelle Acevedo
Tokyo Electron Limited
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