Coating apparatus – Control means responsive to a randomly occurring sensed... – Responsive to attribute – absence or presence of work
Reexamination Certificate
2000-12-13
2004-01-13
Crispino, Richard (Department: 1734)
Coating apparatus
Control means responsive to a randomly occurring sensed...
Responsive to attribute, absence or presence of work
C118S713000, C118S052000, C118S056000, C134S902000
Reexamination Certificate
active
06676757
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-359935, filed Dec. 17, 1999; and No. 11-360990, filed Dec. 20, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for forming a coating film on a substrate to be treated such as a semiconductor wafer or an LCD substrate (a glass substrate for a liquid crystal display) by applying a coating solution, for example, a resist solution or the like thereto, and a coating unit.
In fabrication processes of a semiconductor device or an LCD, a resist pattern for a substrate to be treated is formed by a technology called photolithography. An apparatus for forming the resist pattern is composed by connecting an aligner to a coating and developing system provided with a cassette mounting section for carrying a wafer into/from a cassette, a coating unit for applying a resist solution, thermal treatment units for performing treatments such as heating and cooling, a developing unit for performing development, a main arm for transferring the wafer and so on.
Conventionally, the resist solution has been applied in the above-described coating unit by a so-called spin coating method. This is a method by which the resist solution is spread by centrifugal force of the wafer so that a solution film is formed over the entire wafer by providing a rotatable spin chuck in a cup surrounding the sides of the substrate over the entire circumference thereof, horizontally suction-holding the wafer by the spin chuck, and rotating the wafer while supplying the resist solution to the wafer from a nozzle above the central portion of the wafer.
Incidentally, a line width of the resist pattern to be formed is proportional to a film thickness of a resist film and an exposure wavelength. Accordingly, formation of thinner films is attempted by increasing the rotational frequency of the wafer in the spin coating method since it is necessary to make a solution film thinner to a minimum in order to cope with growing demands for a finer pattern in recent years.
However, since the wafer is rotated at a high speed in the above-described method, there is a problem that a circumferential speed of the inner circumferential portion of the wafer becomes high compared with that of the outer circumferential portion thereof, whereby air turbulence occurs at the outer peripheral portion of the wafer particularly when the wafer is upsized. The turbulence becomes a factor of impairing the formation of finer patterns since it changes the film thickness, bringing about the non-uniformity in film thickness of the entire wafer.
Further, the resist solution is spread to be blown off from the central portion of the wafer toward the peripheral portion thereof, causing a big waste of resist solution since it scatters from the peripheral portion thereof to the side of the cup. In addition, there has been a problem that the resist solution applied to portions except for a circuit formation region such as the peripheral portion or the resist solution adhered to the cup due to the scatter is hardened, which results in a cause of particles.
In view of such circumstances, a method independent of the spin coating method has been examined. According to this method, a resist solution is supplied to a wafer W in a manner of so-called single stroke by reciprocating a nozzle N in an X-direction and at the same time intermittently moving the wafer W in a Y-direction while supplying the resist solution RE from a discharge hole having a fine diameter of the nozzle N provided above the wafer W as shown in FIG.
34
. Incidentally, it is preferable that the portions except for the circuit formation region on the wafer W are covered with a mask to prevent the resist solution from adhering to the periphery or the back surface of the wafer W in this case.
The wafer W is not rotated in this method, whereby the inconvenience as described above is resolved and application can be performed without causing waste. However, a thinner which dissolves a resist constituent is not shaken off unlike in the spin coating and remains intact on the wafer. For example, although no more than about 10% of the thinner remains when the spin coating is performed, substantially 100% of the thinner remains in the manner of single stroke. Therefore, when the wafer is transferred to a heating plate and undergoes drying after being applied with the resist solution, it requires long time to volatilize the thinner, and an amount of volatilization varies within the wafer since it is hard to evenly conduct heat to the resist solution, whereby the uniformity in film thickness of the film to be obtained is deteriorated even if the resist solution is uniformly applied purposely. Further, variations in the amount of volatilization within wafer become wide while the wafer is transferred to the heating plate by a main arm since the amount of volatilization is large on the wafer after being applied with the resist solution, also resulting in a factor which deteriorates the uniformity in film thickness of the resist film.
BRIEF SUMMARY OF THE INVENTION
The present invention is made in view of the aforesaid circumstances and its object is to provide a coating film forming apparatus capable of increasing yields of a coating solution and forming a uniform coating film, and a coating unit.
A coating film forming apparatus according to the present invention comprises a cassette mounting section on which a substrate cassette housing a plurality of substrates is mounted, a coating unit for applying the coating solution to the substrate taken out of the substrate cassette which is mounted on the cassette mounting section, plural treatment units for performing at least either pre-treatment or post-treatment for treatment of applying the coating solution, and a main transfer mechanism for transferring the substrate between the coating unit and the treatment units, the coating unit having (a) a coating section including a substrate holding portion for holding the substrate, a coating solution nozzle for discharging the coating solution to the substrate, provided to be opposed to the substrate held by the substrate holding portion, and a drive mechanism for moving the coating solution nozzle relatively to the substrate along a surface thereof while discharging the coating solution to the surface of the substrate from the coating solution nozzle, and (b) a reduced-pressure drying section for drying under a reduced-pressure atmosphere the substrate which is applied with the coating solution in the coating section. In this invention, application is performed while the coating solution is discharged, for example, in a line shape having a fine diameter from the coating solution nozzle. In addition it is preferable to employ a mask for covering portions except for a region of coating film formation on the substrate and receiving the coating solution from the coating solution nozzle.
According to this invention, quick drying can be performed since drying is performed under reduced pressure even if a large amount of solvent remains in the coating solution applied to the substrate, and a temperature of the coating film within wafer can be maintained uniform by non-heating or heating at a low temperature even if heating is performed. Additionally, drying under reduced pressure can be quickly performed before volatilization of the solvent proceeds so far without waiting the main transfer mechanism after the application since the reduced-pressure drying section is provided in the coating unit, whereby the uniformity within the substrate in film thickness of the coating film can be maintained. Hence, it is possible to increase the yields of the coating solution and besides form the uniform coating film.
The coating unit may be structured to so as to be provided with a coating film removing section for removing the coating film at a peripheral portion of the substrate which is
Akimoto Masami
Esaki Yukihiko
Ishizaka Nobukazu
Kitano Takahiro
Koga Norihisa
Crispino Richard
Koch, III George R.
Oblon, Spivak, McClelland, Maier & Nestadt, P.C.
Tokyo Electron Limited
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