Photoresist-coating and photoresist-coating method using the same

A photoresist-coating apparatus includes a substrate on which a particle-detecting area and an invalid particle-detecting area are defined, a nozzle discharging photoresist to the substrate and moving along a direction, and a particle-detecting sensor controlling on and off of the nozzle in the particle-detecting area according to presence of particles, wherein in the invalid particle-detecting area, the nozzle operates independently from detection of the particle-detecting sensor.

This application claims the benefit of Korean Patent Application No. 2008-0040384, filed on Apr. 30, 2008, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photolithography process, and more particularly, to a photoresist-coating apparatus and a photoresist-coating method using the same.

2. Discussion of the Related Art

With the rapid development of information technology, flat panel display (FPD) devices having advantages of thin thicknesses, light weights and low power consumption, have been developed and have replaced cathode ray tubes (CRTs). The FPD devices include liquid crystal display (LCD) devices, plasma display panels (PDPs), electroluminescent display (ELD) devices and field emission display (FED) devices.

An FPD device may be manufactured through a substrate-fabricating process for forming first and second substrates and a cell process for completing the FPD device by attaching two substrates with a phosphoric material layer or a polarizing material layer therebetween.

In general, to shorten processes and improve production yields, the substrate-fabricating process and the cell process may proceed over large-sized substrates, each of which may include a plurality of cells corresponding to respective display panels and may be referred to as a mother glass substrate.

According to this, in the substrate-fabricating process, thin film deposition, photolithography and etching steps may be repeatedly performed over first and second large-sized substrates to form elements such as pixels and thin film transistors in each cell area.

Meanwhile, in the cell process, seal patterns for attaching substrates may be formed on one of the first and second large-sized substrates, the first and second large-sized substrates may be attached with a polarization material layer, for example, therebetween, and the attached large-sized substrates may be cut by each cell to obtain a plurality of flat panel display devices.

Here, the photolithography step includes applying photoresist to a substrate which includes a thin film thereon, exposing the photoresist to light through a mask which includes predetermined patterns, and developing the light-exposed photoresist to thereby form photoresist patterns corresponding to the patterns of the mask.

At this time, to apply the photoresist to the substrate, a spin coating method or a slit coating method may be used. In the spin coating method, the photoresist may be dropped on the substrate, and then the substrate may be turned, so that the photoresist may be uniformly applied to the substrate. In the slit coating method, the photoresist may be applied to the substrate by scanning a nozzle which has a slit shape along a direction and discharging the photoresist through the nozzle.

The spin coating method has an advantage that the substrate can be uniformly coated with the photoresist. However, as the size of the substrate increases to provide a large-sized display device, the substrate gets large and heavy, and thus it is difficult to turn the substrate. Accordingly, recently, the slit coating method has been widely used.

FIG. 1is a view of illustrating a slit coating apparatus according to the related art.

InFIG. 1, a substrate2to be processed is disposed on a stage10, and a slit coating apparatus20for applying photoresist to the substrate2is disposed over the stage10.

The slit coating apparatus20includes a storage unit30, a supply channel34and a nozzle36. The storage unit30stores and supplies photoresist. The supply channel34provides a path of the photoresist from the storage unit30to the nozzle36. The nozzle36discharges the photoresist to the substrate2on the stage10.

The nozzle36may be a slit nozzle having a bar shape across and over the substrate10. The nozzle36scans and moves along a direction and discharges the photoresist on a substantially entire surface of the substrate2, thereby coating the substrate2with the photoresist.

However, the related art slit coating apparatus20has several disadvantages.

More particularly, even though particles exist on the substrate2, the related art slit coating apparatus20does not have any means settling the matter, and a photoresist layer may be non-uniformly formed. To solve the problem, the slit coating apparatus20may include a particle-detecting sensor (not shown), and the particles on the substrate2can be detected by the particle-detecting sensor. However, there frequently happens misoperation of the particle-detecting sensor.

As a first cause of the misoperation, the substrate2, on which a photoresist layer is formed by the slit coating apparatus20, may be a mother glass substrate and may be cut into a plurality of cell areas, each of which constitutes one display panel, in the following cutting step. The particle-detecting sensor may misoperate due to interference phenomenon from difference between layers in the cell areas and in regions between adjacent cell areas. That is, layers formed in each cell area differ from layers in the region between adjacent cell areas.

Second, to uniformly apply the photoresist to the substrate2, the nozzle36may accelerate or decelerate at a specific area. At this time, even though there is no particle, the particles-detecting sensor may perceive that there exist particles due to acceleration or deceleration of the nozzle36and may misoperate.

When the particle-detecting sensor misoperates, an operator does not judge that the particle-detecting sensor misoperates but judges that there exist particles on the substrate2. Accordingly, after stopping the slit coating process, the particles on the substrate2are checked. Therefore, the efficiency of the process is lowered.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a photoresist-coating apparatus and photoresist-coating method using the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An advantage of the present invention is to provide a photoresist-coating apparatus and a photoresist-coating method using the same that exactly detect particles on a substrate and uniformly form a photoresist layer.

Another advantage of the present invention is to provide a photoresist-coating apparatus and a photoresist-coating method using the same that prevent misoperation of a particle-detecting sensor and improve production yields.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a photoresist-coating apparatus includes a substrate on which a particle-detecting area and an invalid particle-detecting area are defined, a nozzle discharging photoresist to the substrate and moving along a direction, and a particle-detecting sensor controlling on and off of the nozzle in the particle-detecting area according to presence of particles, wherein in the invalid particle-detecting area, the nozzle operates independently from detection of the particle-detecting sensor.

In another aspect of the present invention, a photoresist-coating method includes discharging photoresist to a substrate by a nozzle moving along a direction while a particle-detecting sensor detects particles on the substrate, wherein a particle-detecting area and an invalid particle-detecting area are defined on the substrate, and in the invalid particle-detecting area, discharging photoresist is performed independently from detection of the particle-detecting sensor.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 2is a flow chart showing a photolithography process according to an exemplary embodiment of the present invention.

InFIG. 2, the photolithography process is largely divided into coating, light-exposing, developing and baking steps, and the baking step includes pre-baking, soft-baking and hard-baking steps.

At first step st110, pre-baking step is performed. Here, moisture remaining in a thin film deposited on a substrate may be removed, and an adhesive strength between the thin film on the substrate and a photoresist to be formed later may be improved.

At second step st120, photoresist is applied to the substrate by a slit coating method. The photoresist may be discharged through a nozzle having a slit shape and scanning along a direction over the substrate, and the photoresist may be uniformly applied to the substrate to form a photoresist layer.

At third step st130, soft-baking is performed. To vaporize volatile components such as solvent of the photoresist, the soft-baking step may be carried out in an in-line system using a substrate-heating apparatus such as a hot plate under the atmosphere condition.

Next, at fourth step st140, aligning and light-exposing are performed. The substrate passing through the vaporizing step may be aligned with a mask, and the substrate may be exposed to light through the mask to transfer patterns of the mask to the substrate. Here, the photoresist layer may include a first portion, which is exposed to the light and is chemically changed, and a second portion, which is not exposed to the light.

At fifth step st150, the first portion or the second portion of the photoresist layer is selectively removed by a developer depending on the type of the photoresist layer, and photoresist patterns corresponding to the patterns of the mask are formed.

At sixth step st160, hard-baking is performed. The substrate may be heated so that the volatile elements in the photoresist patterns are completely removed. Accordingly, the photoresist patterns become dense and uniform.

According to the first to sixth steps st110to st160, the thin film is selectively exposed by the photoresist patterns.

At seventh step st170, the exposed portions of the thin film are removed, and then the remaining photoresist patterns are removed. Therefore, intended patterns are obtained.

In the second step st120, a slit coating apparatus according to embodiments of the present invention may be used for applying the photoresist to the substrate that accurately detects particles on the substrate and enables the photoresist layer to be uniformly formed on the substrate.

FIG. 3is a view of schematically illustrating a slit coating apparatus according to an embodiment of the present invention and also shows a substrate on which a photoresist layer is formed by the slit coating apparatus.

InFIG. 3, a substrate102to be processed is disposed on a stage210, and a slit coating apparatus220for applying photoresist to the substrate102is disposed over the stage210.

The slit coating apparatus220includes a storage unit230, a supply channel234, a nozzle236, a thickness-measuring sensor (not shown) and a particle-detecting sensor240. The storage unit230includes stores and supplies photoresist. The supply channel234provides a path of the photoresist from the storage unit230to the nozzle236. The nozzle236discharges the photoresist to the substrate102on the stage210. The thickness-measuring sensor measures the thickness of the substrate102. The particle-detecting sensor240detects particles on the substrate102.

The storage unit230may include at least one canister (not shown) for storing the photoresist and a pressing means (not shown) such as a pump for providing the photoresist to the supply channel234. The supply channel234may include a connecting pipe.

The storage unit230supplies the nozzle236with the photoresist through the supply channel234and applies pressure to the photoresist such that the photoresist is discharged to the outside.

The nozzle236may be a slit nozzle having a bar shape across and over the substrate102with a length corresponding to the substrate102. The nozzle236may include a discharging hole (not shown) having a slit shape at a lower surface of the nozzle236facing the substrate102. A uniform amount of photoresist may be discharged to the substrate102through the discharging hole.

The nozzle236scans and moves from one side to the other side of the substrate102and discharges the photoresist to a substantially entire surface of the substrate102to coat the substrate102with the photoresist while both ends of the nozzle236are supported by a couple of nozzle-transporting units251and253.

Alternatively, the photoresist may be applied to the substrate102by sliding the substrate102on the stage210while the nozzle236is fixed.

The thickness-measuring sensor (not shown) measures the thickness of the substrate102to be coated with the photoresist and controls a distance between the substrate102and the nozzle236according to the measured thickness of the substrate102.

At this time, the distance between the substrate102and the nozzle236may be minutely adjusted considering the viscosity and the amount of the photoresist to be applied. Since the photoresist is dried right after being applied to the substrate102, the viscosity of the applied photoresist may be changed as time passes. Therefore, the distance between the nozzle236and the substrate102should be minutely controlled.

The nozzle236waits while the thickness of the substrate102is measured by the thickness-measuring sensor, and after measuring the thickness of the substrate102, the nozzle236scans and moves.

In addition, a light-emitting portion241and a light-receiving portion243of the particle-detecting sensor240are installed in front of the couple of nozzle-transporting units251and253supporting both ends of the nozzle236, respectively. Light245emitted from the light-emitting portion241is received by the light-receiving portion243, and thus the amount of light is determined. The light245may be a laser beam.

At this time, if there is no particle between the light-emitting portion241and the light-receiving portion243, all the light245emitted from the light-emitting portion241are incident on the light-receiving portion243. On the other hand, if there exist particles between the light-emitting portion241and the light-receiving portion243, some of the light245emitted from the light-emitting portion241are screened by the particles, and only the others of the light245are incident on the light-receiving portion243. Accordingly, the amount of light received by the light-receiving portion243is reduced as compared with a normal state, and in this case, it is determined that there exist particles between the light-emitting portion241and the light-receiving portion243.

Like this, if the particles on the substrate102are detected by the particle-detecting sensor240, the slit-coating apparatus220stops the slit-coating process by stopping the nozzle236from discharging the photoresist and moving and by forcing the nozzle to wait. Then, after the particles detected on the substrate102are checked, the particles are removed or the substrate102is disused.

At this time, a particle-detecting area A on the substrate102is subdivided.

More particularly, to uniformly apply the photoresist to the substrate102, the nozzle236may accelerate or decelerate in a specific area. At this time, the particle-detecting sensor240may perceive a minute vibration because of the acceleration or deceleration of the nozzle236. Accordingly, the amount of light received by the light-receiving portion243may change, and the particle-detecting sensor240may recognize that there exist particles in areas where the nozzle236accelerates or decelerates. Accordingly, the areas where the nozzle236accelerates or decelerates are defined as examples of invalid particle-detecting areas B, and the particle-detecting area A is subdivided.

In the invalid particle-detecting areas B, sensing of the particle-detecting sensor240is disregarded, and process time is shortened in comparison to the related art. Thus, stops of the slit-coating apparatus220due to misoperation of the particle-detecting sensor240are decreased.

FIG. 4is a graph of illustrating voltage variation of a particle-detecting sensor in areas where a nozzle accelerates or decelerates.

InFIG. 4, the nozzle236accelerates or decelerates in first and second areas x1and x2, and at these times, the voltage of the particle-detecting sensor240is changed. In general, the voltage variation of the particle-detecting sensor240means that the particle-detecting sensor240perceives particles on the substrate102.

However, the first and second areas x1and x2in which the nozzle236accelerates or decelerates may be areas where the nozzle236starts moving at one side of the substrate102to discharge the photoresist on the substrate102on the stage210and where the nozzle236stops moving at the other side of the substrate102after discharging the photoresist on a substantially entire surface of the substrate102. Or, the first and second areas x1and x2may be areas where the nozzle236decelerates so that the thickness of the substrate102is measured by the thickness-measuring sensor (not shown) and where the nozzle236accelerates to move again after measuring the thickness of the substrate102by the thickness-measuring sensor.

That is, the particle-detecting sensor240does not detect real particles on the substrate102, but the particle-detecting sensor240misoperates as if the particles are detected due to minute vibration from the acceleration or deceleration of the nozzle236.

Accordingly, even though the particle-detecting sensor240detects particles in the first and second areas x1and x2of the graph while the photoresist is uniformly applied to the substrate102by the slit-coating apparatus220, the perception of the particle-detecting sensor240is disregarded, and the slit-coating process is normally performed. Here, the first and second areas x1and x2become the invalid particle-detecting areas B.

In the meantime, the particle-detecting sensor240may include a control unit (not shown) such that the particle-detecting sensor240ignores the perception in the invalid particle-detecting areas B and the slit-coating apparatus220normally performs the process. The control unit may be a computer, and the areas where the nozzle236accelerates or decelerates are defined in the control unit. The particle-detecting sensor240may further include a monitor device (not shown) that shows the result of perception of the particle-detecting sensor240in the invalid particle-detecting areas B.

Here, the substrate102may be a substrate for a liquid crystal display device to be processed by the slit-coating apparatus220. To reduce the process and increase the production yields, the substrate102may be a mother glass substrate including a plurality of cell areas101, each of which corresponds to a display device.

As shown inFIG. 5, in the control unit, areas where there may occur an interference phenomenon due to difference between layers in the cell areas101and in regions between adjacent cell areas101on the substrate102are also defined as the invalid particle-detecting areas B in addition to the areas where the nozzle236accelerates or decelerates. Accordingly, the control unit enables the particle-detecting sensor240to ignore the perception in the invalid particle-detecting areas B.

As stated above, by defining the invalid particle-detecting areas B and disregarding the perception of the particle-detecting sensor240in the areas B, process time is shortened in comparison to the related art, and this is why it is decreased that the slit-coating apparatus220stops due to misoperation of the particle-detecting sensor240.

That is, even though there is no particle, the particle-detecting sensor240may misoperate as if the particles are detected due to minute vibration from the acceleration or deceleration of the nozzle236and the interference phenomenon by difference between layers in the cell areas101and in regions between adjacent cell areas101on the substrate102. At this time, the operator may not judge that the particle-detecting sensor misoperates but may judge that there exist particles on the substrate102. To check the particles on the substrate102, the slit coating process may be stopped. Therefore, the efficiency of the process may be lowered. However, in the embodiments of the present invention, problems due to misoperation of the particle-detecting sensor240are prevented.

FIG. 6Ais a graph of illustrating measured time for each step of a photolithography process using a slit coating method, wherein a particle-detecting sensor detects particles on a substrate without defining invalid particle-detecting areas.FIG. 6Bis a graph of illustrating measured time for each step of a photolithography process using a slit coating method, wherein a particle-detecting sensor detects particles on a substrate with defining invalid particle-detecting areas according to an exemplary embodiment of the present invention.

InFIG. 6A, an average time for each step of the photolithography process is 52.5 seconds. InFIG. 6B, an average time for each step of the photolithography process according to the present invention is 51.9 seconds, which is reduced by 0.6 seconds as compared with the average time for each step of the photolithography process according to the related art in which the invalid particle-detecting areas are not defined.

This is because the process is less often stopped than the related art, in which the whole slit coating process is stopped when the particle-detecting sensor240operates as it detects particles due to minute vibration by the acceleration or deceleration of the nozzle236or due to difference between layers in the cell areas and in regions between adjacent cell areas on the substrate102even if there is no particle in specific areas. Accordingly, process speed can be improved.

Meanwhile, the time measured at each step of the photolithography process inFIGS. 6A and 6Bis process time required when the photolithography process is completely performed over one substrate102. To reduce process time and costs, the photolithography process may be carried out with an in-line system in which the substrate102is processed while being transferred. In embodiments of the present invention, the time of the photolithography process over the substrate102is reduced by 0.6 seconds, and time of total photolithography processes can be considerably decreased. Accordingly, the production yields of the photolithography process can be rather increased.

FIG. 7is a view for explaining a slit coating method according an embodiment of to the present invention.

InFIG. 7, a substrate102to be coated with photoresist is disposed on a stage210, and a nozzle236of a slit coating apparatus220is disposed over and across the substrate102.

A thickness of one side of the substrate102is measured by a thickness-measuring sensor (not shown) of the slit coating apparatus220, and then the nozzle236scans and moves from one side to the other side of the substrate102by a couple of nozzle-transporting units251and253at a regular speed to thereby discharge and apply photoresist to a substantially entire surface of the substrate102.

At this time, light245such as a laser beam is emitted from a light-emitting portion241of a particle-detecting sensor240, which is installed at one of the moving nozzle-transporting units251and253, and is received by the light-receiving portion243of the particle-detecting sensor240, which is installed at the other of the nozzle-transporting units251and253. According to this, the amount of light is determined, and particles on the substrate102can be detected.

In the meantime, when the nozzle236scans and moves after the thickness of the substrate102is measured by the thickness-measuring sensor (not shown), even though the particle-detecting sensor240operates as it detects particles due to minute vibrations from acceleration of the nozzle236, the nozzle236continuously scans and moves over the substrate102.

Additionally, even though the particle-detecting sensor240operates as it detects particles due to minute vibrations from deceleration of the nozzle236that reaches the other side of the substrate102, the nozzle236disregards this and completes the coating process over the substrate102.

That is, the areas where the nozzle236accelerates or decelerates are defined as invalid particle-detecting areas B ofFIG. 3, and it is disregarded that the particle-detecting sensor240detects particles in the areas.

Meanwhile, in addition to the areas where the nozzle236accelerates or decelerates, areas where there occurs an interference phenomenon due to difference between layers in cell areas and in regions between adjacent cell areas101on the substrate102may be also defined as the invalid particle-detecting areas B ofFIG. 3.

As stated above, by defining the invalid particle-detecting areas B ofFIG. 3, perception of the particle-detecting sensor240is disregarded in the invalid particle-detecting areas B ofFIG. 3, and process time can be shortened as compared with the related art. Accordingly, problems due to misoperation of the particle-detecting sensor240can be prevented. Moreover, process efficiency can be improved.