Coating processes – Centrifugal force utilized
Reexamination Certificate
1999-11-12
2001-10-09
Beck, Shrive P. (Department: 1762)
Coating processes
Centrifugal force utilized
C427S425000, C427S389700, C118S052000, C118S320000, C118S663000, C118S683000
Reexamination Certificate
active
06299938
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to an apparatus and method of applying a resist solution onto a glass substrate used in, for example, a liquid crystal display (LCD).
The priority of the present application has been claimed on the basis of Japanese Patent Application No. 10/346638 (Nov. 20, 1998). The contents of the Japanese application are incorporated in the present application.
In a producing process of an LCD, the same photolithography as that employed for production of a semiconductor device is employed to form a thin film of ITO (Indium Tin Oxide) and an electrode pattern on a glass substrate for the LCD. According to the photolithography, photoresist is applied onto a substrate, exposed and developed.
In a major resist applying step, spin coating is employed. By the spin coating, a resist solution is dropped onto a glass substrate while rotating the glass substrate, and the resist solution is diffused by the rotationally centrifugal force, to form a uniform resist film on a glass substrate. According to this method, however, most of the resist solution may be dropped from the substrate and wasted. An example teaches that only about 10% of the total amount of the resist contribute to formation of the film.
BRIEF SUMMARY OF THE INVENTION
The present invention is accomplished to solve the above problem, and its object is to provide an apparatus and method capable of reducing an amount of use of a solution.
To solve the problem, the present invention according to its first major concept is a resist solution applying apparatus, comprising a holding and rotating member for rotating while holding a member to be processed; a resist solution discharging nozzle for discharging a resist solution almost at a center of rotation of the member to be processed; a resist solution supplying mechanism for supplying the resist solution to the resist solution discharging nozzle; and a discharge control section connected to the resist solution supplying mechanism, for controlling an amount of the resist solution discharged from the resist solution discharging nozzle to be reduced gradually or in stages, after discharging has been started.
According to this structure, a resist solution extends all over the member to be processed by the centrifugal force after discharging has been started, and a resist solution is further discharged on the extending resist solution. The resist solution discharged after that is easily extended to have a uniform thickness even if an amount of the discharging is reduced. Therefore, even if the amount of discharge is reduced after discharging has been started, the resist solution can be applied all over the member to be processed to have a uniform thickness, and the use of the resist solution can be reduced as compared with that in prior art.
It is preferable that the embodiment comprises a casing for sealing airtight an atmosphere around the member to be processed, while the resist solution is discharged or the member to be processed is rotated. According to the structure, the solvent included in the resist solution is hardly vaporized. Therefore, the advantage of controlling the discharge can be achieved certainly. Further, the supply of the resist solution can be reduced. In this case, it is preferable that the member to be processed and its casing are rotated synchronously with one another. According to this structure, the solvent included in the resist solution ca be made to be vaporized further hardly.
According to the embodiment of the first concept, the discharge control portion controls an amount of the resist solution discharged from the resist solution discharging nozzle to be a predetermined amount in a period from the time when discharging is started to the time when the resist solution has extended all over the member to be processed, and then controls the amount to be gradually reduced.
According to the embodiment of the first concept, the discharge control portion controls an amount of the resist solution discharged to the resist solution discharging nozzle to be a predetermined amount in a period from the time when discharging is started to the time when the resist solution has extended all over the member to be processed, and then controls the amount to be gradually reduced, and further controls the amount to be increased again.
The present invention of the second major concept, in addition to the first concept, provides a resist solution applying apparatus further comprising a rotation speed control portion for controlling a rotation speed of the member to be processed determined by the holding and rotating member, synchronously with the control of the amount of discharge by the discharge control portion.
According to this structure, even when the discharge of the resist solution is limited, the solution can be applied uniformly onto the entire member to be processed.
According to the embodiment of the second concept, the rotation speed control portion controls the rotation speed of the member to be processed determined by the holding and rotating member, to be constant, at least when the amount of the resist solution discharged to the resist solution discharging nozzle is controlled to be reduced gradually.
According to the embodiment of the second concept, the discharge control portion controls an amount of the resist solution discharged from the resist solution discharging nozzle to be a predetermined amount in a period from the time when discharging is started to the time when the resist solution has extended all over the member to be processed, and then controls the amount to be gradually reduced; and the rotation speed control portion controls the rotation speed of the member to be processed determined by the holding and rotating member, to be accelerated when the amount of the resist solution discharged to the resist solution discharging nozzle is a predetermined amount, and controls the rotation speed to be constant when the amount of the resist solution is controlled to be reduced gradually.
According to the embodiment of the second concept, the discharge control portion controls an amount of the resist solution discharged to the resist solution discharging nozzle to be a predetermined amount in a period from the time when discharging is started to the time when the resist solution has extended all over the member to be processed and then controls the amount to be gradually reduced, and further controls the amount to be increased again; and the rotation speed control portion controls the rotation speed of the member to be processed determined by the holding and rotating member, to be accelerated when the amount of the resist solution discharged to the resist solution discharging nozzle is a predetermined amount, controls the rotation speed to be constant when the amount of the resist solution is controlled to be reduced gradually, and controls the rotation speed to be decelerated when the amount of the resist solution is controlled to be increased again.
The present invention according to the third concept provides a method of applying a resist solution, comprising the steps of supplying the resist solution to a member to be processed; extending the resist solution on the member to be processed by rotating the member to be processed in a sealed casing; and controlling an amount of the resist solution discharged onto the member to be processed, to be reduced gradually or in stages after discharging has started.
The present invention according to the fourth concept, in addition to the third concept, provides the method further comprising a step of controlling a rotation speed of the member to be processed, synchronously with the control of the amount of the discharged resist solution.
The present invention according to the fifth concept provides a resist solution applying apparatus, comprising: a holding and rotating member for rotating while holding a member to be processed; a casing for sealing airtight an atmosphere around the member to be processed, while the member to be processed is rotated; a re
Beck Shrive P.
Calcagni Jennifer
Rader Fishman & Grauer
Tokyo Electron Limited
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