# Patent

## Title
Wet etching apparatus and method

## Abstract

A wet etching apparatus and method to shorten processing time and to eliminate formation of unintended mask pattern are described. In the conventional art, after a mask pattern is formed, alien substances such as water mist or stain are left on the substrate. The alien substances act as an etching block in the wet etching process. This generates an unintended mask pattern. The present invention uses ultraviolet light to remove the alien substances prior to the etching process. When the alien substances are removed, the intended mask pattern is generated after the etching process. The wet etching device according to the present invention includes an ultraviolet cleaner and a conveyor to convey substrates to and from the ultraviolet cleaner. Spaces for the ultraviolet cleaner and the conveyor are created in the wet etching apparatus by reducing space for cassettes and reducing space required by the loader. As a result, alien substances can be removed without the need for separate sets of equipment, which reduces processing time, simplifies the process, and increases both productivity and reliability.

## Background
FIELD OF THE INVENTION 
This application is a divisional of application Ser. No. 09/731,738 filed on Dec. 8, 2000, now U.S. Pat. No. 6,792,957, the entire contents of which are hereby incorporated by reference.
This invention relates to a wet etching technique, and more particularly to a wet etching apparatus and method that shortens processing time and prevents generation of an unintended mask pattern for etching.


BACKGROUND OF THE INVENTION 
Generally, a liquid crystal display (LCD) is provided with electrode terminals and wires. The terminals and wires include source, gate, and drain electrodes of thin film transistors (TFT's), which are used as switching devices within a liquid crystal cell. The terminals and wires also include data lines for applying a video data signal to each liquid crystal cell, gate lines for applying a scanning signal thereto, and pixel electrodes and common electrodes for coupling an electric field with a liquid crystal layer.
The electrode terminals and wires are made by depositing an electrode material on a substrate and then wet etching the material using a photoresist mask and patterning the same. The wet etching is performed by precipitating a substrate in an etchant liquid or by jetting the etchant liquid onto the substrate by an injection nozzle to react the etchant liquid with the electrode material.
FIG. 1 shows a structure of a conventional wet etching apparatus. The conventional wet etching apparatus includes a plurality of cassettes 20 within a loader 22, a first robot 26, a waiting part 24, an etching part 28, a tilt drain part 30, a de-ionized rinsing part 32, a second robot 36, and a spin drier 34.
The operation of the conventional apparatus is as follows. A substrate, formed with the photoresist mask pattern, is carried from one of the plurality of cassettes 20 into the waiting part 24 by the first robot 26 positioned within the loader 22. The substrate is then sent to the etching part 28 to carry out the etching.
The etching part 28 jets etchant liquid from an injection nozzle onto the substrate to etch the substrate by an etching reaction of an etching layer with the etchant liquid. Afterwards, the substrate is moved to the tilt drain part 30 which inclines the substrate at a desired angle to drain the etchant liquid left on the substrates. Then, any remaining etchant liquid left on the substrates is completely removed by rinsing with de-ionized water by the de-ionized rinsing part 32.
Thereafter, the second robot 36 carries the substrates from the de-ionized rinsing part 32 into the spin drier 34. The spin drier 34 dries the substrates, thus completing the wet etching process.
A process of forming the electrode terminals and the electrode lines on the substrate using the above-mentioned wet etching method is now described. First, the substrate is cleaned and then an electrode material is deposited on the substrate. Next, a mask pattern is formed on the electrode material layer as follows. Initially, a photoresist material is coated to cover the entire electrode material layer. Then the photoresist material is exposed to light to complete the mask pattern. After the mask pattern is formed, the substrate is carried into the wet etching apparatus as shown in FIG. 1 to perform the wet etching process. Thereafter, the mask pattern on the substrate is removed.
In the conventional process, however, an alien substance, such as a water mist or organic film, is often generated around the mask pattern during patterning. In other words, as shown in FIG. 2, an alien substance 42 may be left on the periphery of the mask pattern 40.
The alien substance 42 acts as an etching block interfering in the wet etching process and thus produces an unintended mask pattern as shown in FIG. 3. The shape of a non-etched portion 46 formed with the mask pattern 40 is not identical to the intended mask pattern. As a result, a shape corresponding to the unintended mask pattern remains after the etching process is complete.
In the conventional art, to prevent the generation of the unintended mask pattern, the alien substance 42 is eliminated by adding a cleaning process after formation of the mask pattern 40 and prior to the wet etching process. The alien substance 42 is eliminated by ashing using a separate wet etching apparatus or by cleaning using a separate ultraviolet equipment mounted with a low-pressure mercury lamp.
However, such conventional elimination process to remove alien substances is not performed during the photoresist formation process or the wet etching process, but is a separate process using different equipment. This requires additional resources and time. Further, it requires that the substrate be transported out of one set of equipment to another and then back. As such, productivity and quality are reduced.
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a wet etching apparatus and method that is capable of shortening a process time as well as effectively preventing the formation of unintended patterns during etching work.
In order to achieve these and other objects of the invention, a wet etching apparatus according to one aspect of the present invention includes an ultraviolet cleaner for eliminating alien substances left on the substrate, and a conveyer for conveying the loaded substrate into the loader and conveying the substrate in which the alien substances have been eliminated the ultraviolet cleaner into the etching unit.
A wet etching apparatus according a second embodiment includes an ultraviolet cleaner cleaning alien substances from a substrate; a conveyor conveying the substrate to and from the ultraviolet cleaner; a loader loading said substrate to the conveyor; and an etching unit etching the substrate that is free of the alien substances.
A wet etching method according to a further aspect of the present invention includes conveying the loaded substrate into an ultraviolet cleaner; irradiating ultraviolet ray onto the loaded substrate to eliminate alien substances left on the substrate; and conveying the substrate, in which the alien substances have been eliminated, into the etching unit to conduct an etching work.
A wet etching method according to a still further aspect of the present invention includes forming a photoresist mask pattern on a substrate, and exposing the substrate to ultraviolet light to remove alien substances.
Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.



BRIEF DESCRIPTION OF THE DRAWINGS 
These and other objects of the invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings, in which:
FIG. 1 is a plan view showing a structure of a conventional wet etching apparatus;
FIG. 2 represents a plane structure and a sectional structure of a substrate with a mask pattern;
FIG. 3 represents a plane structure and a sectional structure of the pattern after etching the substrate shown in FIG. 2;
FIG. 4 is a plan view showing a structure of a wet etching apparatus according to an embodiment of the present invention; and
FIG. 5A and FIG. 5B are plan views showing substrate shapes before and after cleaning of the substrate using the eximer ultraviolet cleaner of the wet etching apparatus of FIG. 4



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A wet etching apparatus according to an embodiment of the present invention is shown in FIG. 4. In this wet etching apparatus, an eximer ultraviolet cleaner is mounted within the wet etching apparatus. More specifically, the number of cassettes loaded at the loader is reduced by one from the conventional wet etching apparatus to provide the necessary space to mount the eximer ultraviolet cleaner. The alien substance, such as an organic film or a water mist, left on the substrate is eliminated by the eximer ultraviolet cleaner just before the wet etching takes place.
Referring to FIG. 4, in addition to the elements of the conventional apparatus shown in FIG. 1, the present wet etching apparatus further includes an eximer ultraviolet cleaner 72 and a conveyer 76. In other words, the cleaner 72 and the conveyor 76 are integrated into the wet etching apparatus. A space for the eximer ultraviolet cleaner 72 is created by reducing the number of cassettes, e.g., by at least one, and an amount of space taken up by the conveyor is created by reducing the space of the loader 22. The conveyor 76 transfers the substrate between the eximer ultraviolet cleaner 72 and the waiting part 24.
The process of forming the photoresist mask pattern on the substrate prior to the wet etching work is similar to the conventional art. First, the substrate is cleaned. Then, an electrode material is deposited on the substrate. Next, a photoresist mask pattern is formed on the electrode material layer.
The process of forming the mask pattern, according to the embodiment of the present invention, is as follows. Initially, the photoresist material is coated to cover the entire electrode material layer. Then the photoresist is exposed to light and patterned to complete the mask pattern.
A plan view of the substrate in which the photoresist mask pattern is formed by the above-mentioned work is as shown in FIG. 5A. As seen, an alien substance 102, such as water mist or a stain, may be left around a mask pattern 100. The substrate, with the mask pattern 100, is arranged in sheets with other substrates in a cassette 20. The sheets may be arranged in groups of ten and each cassette 20 may contain one such group of sheets. Each substrate, arranged within a cassette 20, is loaded in sequence with other substrates onto the conveyer 76 by the first robot 26 within the loader 22.
The conveyer 76 includes of an upper conveyer 92 and a lower conveyer 94. First, the substrate is loaded onto the upper conveyer 92 by the first robot 26. The substrate loaded on the upper conveyer 92 is conveyed into the eximer ultraviolet cleaner 72, such as by a rolling operation.
The eximer ultraviolet cleaner 72 includes an eximer ultraviolet lamp. An ultraviolet ray is irradiated from the ultraviolet lamp onto the substrate. When the ultraviolet ray is irradiated, the alien substance 102 left around the mask pattern 100 as shown in FIG. 5A reacts due to the ultraviolet light and generates ozone gas O3. This eliminates the alien substance 102.
FIG. 5B shows a plan view of the substrate after the alien substance 102 is eliminated. As seen, alien substance 102 left around the mask pattern 100 is removed and leaves the intended mask pattern 100 on the substrate.
Then the substrate, free from alien substances, is conveyed from the eximer ultraviolet cleaner 72 on to the lower conveyer 94, and then is conveyed to the waiting part 24. Note that the lower conveyer may need to rotate 90° before conveying the substrate to the waiting part 24 depending on the construction.
Then the substrate, positioned at the waiting part 24, is sent to the etching part 28 to carry out the etching process. The etching part 28 jets etchant liquid from an injection nozzle onto the mashed substrate to etch exposed portions of the substrate. Afterwards, the tilt drain part 30 inclines the substrate at a desired angle to drain the etchant liquid left on the substrates. Then, any remaining etchant liquid left on the substrates is completely removed by rinsing with de-ionized water by the de-ionized rinsing part 32.
Thereafter, the second robot 36 carries the substrates from the de-ionized rinsing part 32 into the spin drier 34. The spin drier 34 dries the substrates, thus completing the wet etching process.
In the present wet etching apparatus and method, the alien substance 102, which acts as an etching block, is eliminated with the eximer ultraviolet cleaner 72. Thus the unintended mask pattern is not produced during the etching process. This is done without the need for any separate equipment. Thus, processing is shortened and simiplified, and the productivity and reliability are increased.
Although the present invention has been explained by the embodiments shown in the drawings described above, it should be understood to the ordinary skilled person in the art that the invention is not limited to the embodiments, but rather that various changes or modifications thereof are possible without departing from the spirit of the invention. Accordingly, the scope of the invention shall be determined only by the appended claims and their equivalents.

## Claims

1. A method to clean alien substances from a substrate with a photoresist mask pattern, the method comprising:
forming the photoresist mask pattern on the substrate;
conveying the substrate to a clean device after forming the photoresist mask pattern on the substrate;
exposing the substrate to an ultraviolet light to remove the alien substances formed on the substrate when the photoresist mask was formed, after conveying the substrate to the clean device; and
conveying the substrate from the cleaning device to an etching station after exposing the substrate to the ultraviolet light to remove the alien substances.

2. The method according to claim 1, wherein an eximer ultraviolet light is used as the ultraviolet light in the exposing the substrate to the ultraviolet light.

3. A method for wet etching, comprising:
cleaning a substrate having alien substances formed when a photoresist mask pattern is formed, using an ultraviolet cleaner after the photoresist mask pattern is formed on the substrate;
conveying the substrate to the ultraviolet cleaner prior to cleaning the substrate, and conveying the substrate from the ultraviolet cleaner after cleaning the substrate;
loading the substrate to a loader; and
etching, using the ultraviolet cleaner, the substrate in an etching unit after the alien substances are cleaned from the substrate.

4. The method according to claim 3, wherein the substrate includes at least one of a gate electrode, a source electrode, a drain electrode, a pixel electrode, and a protective layer.

5. The method according to claim 3, wherein the substrate includes at least one of a black matrix and a common electrode.

6. The method according to claim 3, further comprising:
flowing an etchant on the substrate in a tilt drain part;
eliminating the etchant on the substrate in a de-ionized rinse part having a de-ionized water; and
drying the de-ionized water in a spin drier.

7. The method according to claim 1, wherein conveying the substrate to the clean device comprises conveying the substrate to the clean device located at a predetermined area in a loader on which a plurality of cassettes arranged with the substrate are loaded.

8. The method according to claim 1, wherein conveying the substrate to the ultraviolet cleaner comprises conveying the substrate to the ultraviolet cleaner located at a predetermined area in a loader on which a plurality of cassettes arranged with the substrate are loaded.

9. A method for wet etching a substrate, comprising:
conveying, using a conveyor contained within a wet etching apparatus, the substrate onto which a photoresist mask has been formed into an ultraviolet light cleaner in the wet etching apparatus;
removing alien substances from the substrate using the ultraviolet light cleaner;
conveying, using the conveyor, the substrate from the ultraviolet light cleaner into an etching part in the wet etching apparatus after the alien substances are removed from the substrate; and
wet etching the substrate using the etching part after the substrate is conveyed to the etching part.

10. The method according to claim 9, wherein removing the alien substances includes exposing the substrate to an ultraviolet light from an ultraviolet light source in the ultraviolet light cleaner.

11. The method according to claim 9, wherein the alien substances removed include any one or more of an organic film, water mist, or water stain.

12. The method according to claim 9, wherein the removing the alien substances includes exposing the substrate to an ultraviolet light using an eximer ultraviolet lamp as an ultraviolet light source.

13. The method according to claim 9, wherein conveying the substrate into the ultraviolet light cleaner comprises:
loading the substrate from a cassette to the conveyor; and
conveying, using the conveyor, the substrate loaded from the cassette into the ultraviolet light cleaner.

14. The method according to claim 9, wherein the conveyor includes a first conveyor and a second conveyor different from the first conveyor, and conveying the substrate into the ultraviolet light cleaner comprises conveying the substrate from a cassette into the ultraviolet light cleaner using the first conveyor.

15. The method according to claim 14, wherein conveying the substrate from the ultraviolet light cleaner into the etching part comprises conveying the substrate from the ultraviolet light cleaner into the etching part using the second conveyor.

16. The method according to claim 9, further comprising removing the photoresist mask from the substrate after the wet etching.

17. The method according to claim 16, wherein removing the photoresist mask comprises:
moving the substrate from the etching part to a tilt drain part in the wet etching apparatus;
draining an etchant from the substrate by tilting the tilt drain part;
rinsing the etchant from the substrate using de-ionized water using a de-ionized rinsing part in the wet etching apparatus; and
spin drying the substrate after the etchant is drained and rinsed using a spin drier in the wet etching apparatus.

18. The method according to claim 9, wherein conveying the substrate into the ultraviolet light cleaner comprises conveying the substrate to the ultraviolet light cleaner located at a predetermined area in a loader on which a plurality of cassettes arranged with the substrate are loaded.

19. The method according to claim 9, wherein the substrate includes at least one of a gate electrode, a source electrode, a drain electrode, a pixel electrode, and a protective layer.

20. The method according to claim 9, wherein the substrate includes at least one of a black matrix and a common electrode.