JP2001334220A - Method for cleaning substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cleaning a substrate by which the re- deposition of a chemical solution to the surface of the substrate following the scattering of mist is prevented from occurring in a spin cleaning process using a spin cup in which a spin table and the substrate rotate during a drying treatment step. SOLUTION: An intermediate drying treatment step is provided in an intermediate stage between a treatment step for cleaning the substrate 18 and a final drying treatment step. Next, the chemical solution adhering to the substrate 18, the spin cup 11 or the like is wiped off in the intermediate drying treatment step and is washed away in a rinsing treatment step. Thus the chemical solution is prevented from adhering again to the surface of the substrate 18 in the final drying treatment step. Consequently, the improvement of a cleaning effect upon the substrate 18, the upgrading of the product quality of a liquid crystal display device itself using the substrate 18 and the yield increase can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cleaning a substrate used in a liquid crystal display device, a semiconductor device, and the like.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device has transparent pixel electrodes arranged in a matrix and connected to a plurality of TFTs on a transparent insulating substrate generally made of glass material. An array substrate having an alignment film formed thereon is included. A transparent electrode and an alignment film are sequentially formed on a transparent insulating counter substrate, also made of a glass material, which is disposed to face the array substrate. In the case of color display, three primary color RGB color filters and the like are provided. ing.

A film forming and patterning technique is frequently used for the array substrate or the counter substrate. In these film forming and patterning steps, high-density and high-definition film forming or patterning is performed by using a fine processing technique. For this purpose, it is necessary to sufficiently clean the substrate itself or a substrate such as an array substrate and a counter substrate that have been formed or patterned.

As a method for cleaning the substrate, electrolytic ionic water cleaning and functional water cleaning, which can provide a low-cost cleaning effect, have recently attracted attention. This electrolytic ionic water cleaning is performed with respect to a cleaning liquid actually used, such as HCl and NH4.
A large oxidation-reduction potential can be obtained only by adding a small amount of a chemical such as 0H, so that a high cleaning effect is exhibited and a significant cost reduction is possible.

[0005] Recently, as a newer chemical, O.
Functional water cleaning, which is a solution of 2 or H2 dissolved in pure water and used as a cleaning solution, has also been put into practical use. This functional water can be used to produce a cleaning solution having a cleaning effect without adding a special chemical solution. It became possible to reduce.

In employing the electrolytic ion water cleaning and the functional water cleaning, a so-called spin cleaning method for performing cleaning by discharging the cleaning liquid to the cleaning surface side of the rotating substrate while rotating the substrate is mainly used. I have. In this spin cleaning method, a rotatable spin table is arranged in a bowl-shaped spin cup, and above the opening of the spin cup,
A spin cup device provided with a nozzle for discharging a cleaning liquid is used.

Using this spin cup apparatus, the substrate is cleaned in the order of the processing steps shown in FIG. That is, after the substrate to be cleaned is fixed to the spin table, the spin table is rotated at a low speed of about 200 to 300 rpm, and the cleaning liquid is discharged from the nozzle in response to the rotation, and the cleaning surface of the substrate is cleaned with the cleaning solution. Processing (FIG. 5 (a))
Then, the substrate surface rinsed with pure water is rinsed (FIG. 5B).
By rotating the substrate at a high speed of about 00 rpm to 2000 rpm, the substrate is drained and spin-dried (FIG. 5C) using centrifugal force.

Here, a specific example of a conventional substrate cleaning method will be described below. First, the first conventional example is
A glass substrate having a size of 300 mm × 400 mm and an Al film having a thickness of 8000 ° formed by sputtering is fixed on a spin table.

Then, the spin table is rotated at a low speed of 200 rpm, and a hydrochloric acid solution for cleaning is ejected from the nozzles on the spin table for 10 seconds to clean the cleaning surface of the substrate. Then, while rotating the spin table at the same rotation speed at a low speed, pure water was supplied from the nozzle for 20 seconds.
The substrate surface is rinsed by discharging c. Thereafter, the spin table is rotated at a high speed of 2000 rpm for 30 seconds to perform draining and drying of the substrate.

In this way, the substrate is cleaned, and as a result of counting foreign substances (mist) on the substrate surface after the completion of the cleaning, about 100 foreign substances having a size of 1 μm or more are detected. When the detected foreign matter was confirmed with a microscope, it was found that a hole having a size of several tens of μm was formed in the Al film. From this, it was confirmed that the mist due to the cleaning chemical liquid was re-adhered to the cleaned surface.

Next, a second conventional example cleaned by another method will be described. The substrate used in this example is a glass substrate of the same size, on which a SiO ₂ film is formed by PE-CVD.
And deposited on the SiO ₂ film.
A substrate on which an a-Si film was deposited to a thickness of 1000 ° by the same method was used.

This substrate is fixed on a spin table, and
A cleaning process is performed by rotating the nozzle at a low speed of 00 rpm, discharging hydrogen peroxide solution from the nozzle for 30 seconds, and then discharging a 0.5% solution of hydrofluoric acid (HF) for 60 seconds at the same rotation speed. Thereafter, the rinsing process is performed by discharging pure water from the nozzle for 30 seconds at the same rotation speed.
Finally, the spin table is rotated at a high speed of 2000 rpm for 30 seconds to perform draining and drying of the substrate.

As a result of counting the number of foreign substances on the substrate surface after the completion of the cleaning process, about 100 foreign substances having a size of 1 μm or more were detected. Traces that were considered to be the effect of

These conventional examples can be summarized as shown in Table 1.

[Table 1]

[0015]

In the spin cleaning method, the substrate is spin-dried by rotating the substrate at a high speed. Therefore, when the substrate is dried at a high speed, a spin table and a cleaning process fixed to the spin table are performed. As the substrate rotates at a high speed, an air current is generated in the spin cup due to the rotation, and the mist rides on the air flow in the spin cup, and the mist is dried during or on the surface of the dried substrate. There was a problem of sticking.

The generation of the air flow in the spin cup is difficult to avoid due to the high speed rotation of the spin table and the substrate. Particularly, when the substrate has a rectangular shape such as an array substrate for an active matrix or a counter substrate. Due to the difference in length between the short side and the long side of the substrate, the turbulence of the airflow is promoted, and this has resulted in the creation of an environment in which the mist is more likely to adhere again.

When the mist re-adheres to the substrate surface, the chemical liquid remains on the adhering portion and the surface state of the adhering surface changes, which adversely affects the characteristics of the array substrate and the counter substrate. Was causing it.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for cleaning a substrate in which mist re-adhering to the substrate surface is reduced.

[0019]

According to the present invention, there is provided a cleaning method in which a substrate is placed and fixed on a rotatable spin table, the spin table is rotated, and a cleaning liquid is discharged onto the cleaning surface side of the substrate to perform cleaning. A cleaning step of rinsing the cleaned substrate; and a drying step of drying the rinsed substrate, wherein the cleaning method includes an intermediate step between the cleaning step and the drying step. A method for cleaning a substrate, comprising a drying step.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing steps of a method for cleaning a substrate according to the present invention.

The substrate on which a film formation or patterning treatment is performed, such as a single substrate or an array substrate or a counter substrate, is shown in FIG.
First, as shown in FIG.
While rotating at a low speed of about pm, a cleaning liquid (chemical liquid) is discharged onto the substrate surface, the cleaning liquid is spread over the entire surface of the substrate, and the substrate is cleaned with the chemical liquid. After the cleaning processing, the substrate is rotated at a high speed of 2000 rpm. An intermediate drying process is performed as shown in FIG. At the time of the intermediate drying process, the spin drying method is used, so that the substrate itself is dried with the high-speed rotation, but the chemical solution remaining in the spin cup is also dried.

At the time of this spin drying, since the chemical solution adhering to the inner wall of the spin cup can be removed, there is also an effect of reducing the concentration of the chemical solution in the mist at the time of final drying.

From this intermediate drying processing state, a rinsing processing shown in FIG. By performing this rinsing treatment, most of the chemical solution attached to the substrate surface or the spin cup wall surface is washed away,
For this reason, the final drying treatment step shown in FIG. In this final drying process, the substrate is spin-dried again to complete the cleaning of the substrate.

In the final drying treatment step, a rinsing treatment has been performed once in the preceding stage, and since most of the chemicals have been washed away, the residual amount is much smaller than that of the conventional chemicals. Therefore, the adverse effect of the chemical solution in the mist can be reduced more reliably.

The method for cleaning a substrate shown in FIG. 1 has the advantages that the amount of pure water used in the rinsing process is small and that the time required for the process is short.

Next, another embodiment will be described with reference to FIG. In the case of the embodiment of FIG. 2, the rinsing process in the middle is divided into two, and an intermediate drying process is arranged between the rinsing processes.
A cleaning process is performed with a cleaning liquid as shown in FIG. 2A, and then a first rinsing process is performed as shown in FIG. 2B. Next, as shown in FIG. 2C, an intermediate drying process is performed by a spin drying method by high-speed rotation, and then, as shown in FIG. 2D, a rinsing process is performed again.
A final drying process is performed as shown in (e), and the cleaning operation of the substrate is completed.

The detailed description of the same steps as those described with reference to FIG. 1 will be omitted.

By rinsing the rinsing step in two steps as described above, the first rinsing step is performed subsequent to the substrate cleaning step. Since the mist is washed off and then subjected to the intermediate drying treatment, the concentration of the chemical solution in the mist that flies due to the generation of the airflow during the intermediate drying treatment is smaller than that in the above-described embodiment. Furthermore, by performing the rinsing process again after the intermediate drying process, the chemical solution remaining at the time of the intermediate drying process can be washed out again, and finally, the chemical solution by the mist in the final drying process step There is an advantage that reattachment can be more reliably prevented.

A spin cup apparatus used in such a method for cleaning a substrate will be described with reference to FIGS. FIG. 3 is a schematic configuration diagram showing the spin cup device in a partial cross section, and FIG. 4 is a schematic plan view of the spin cup device as viewed from the opening side.

The spin cup 11 has a disc-shaped bottom plate 12, and further has a conical partition wall 13 formed by extending a peripheral edge of the bottom plate 12 upward. A portion 14 is provided, and is formed in a substantially bowl shape as a whole. A rotating shaft 16 of a motor 15 is mounted on the center of the bottom plate 12, and a substantially rectangular spin table 17 is fixed to one end of the rotating shaft 16 located inside the spin cup 11. Around the corner of the spin table 17, holding pins 19 for holding a plurality of substrates 18 described later are erected, and on the plane of the spin table 17, the position of the substrate 18 is regulated. Multiple support columns 2
0 are similarly planted. A drain hole 21 for draining the solution is formed in the bottom plate 17, and a drain device 23 is connected to the drain hole 21 via a drain pipe 22.

On the other hand, on the opening 14 of the spin cup 11, a nozzle device 27 having nozzles 24, 25, and 26 for discharging hydrogen peroxide water, HF, and pure water is disposed to face each other. The nozzles 24, 25, and 26 are connected to a solution supply device 28 that supplies the respective solutions by a supply pipe 29. Above the nozzle device 27, N2
An air nozzle 30 for injecting air is arranged, and this air nozzle 30 is also connected to a blower 31 and a supply pipe 32 for supplying air. The nozzle device 27 includes a solution supply device 28,
Alternatively, the supply pipe 29 may be configured to be flexible so that the supply pipe 2
9 or the nozzle device 27 or the solution supply device 28 is connected to the driving device 33, and the nozzle device 27 is configured to be movable. When the solution is not ejected, the nozzle device 27 is positioned away from the opening 14 of the spin cup 11. Only when the solution is ejected, the spin cup 11 is configured to face the opening 14. Similarly, the air nozzle 30 may be configured to be movable. These spin cup devices are actually housed and used in a cleaning tank (not shown).

In order to clean the substrate 18 by using the spin cup apparatus configured as described above, first, the substrate 18 to be cleaned is placed on the support pillar 20 and fixed between the holding pins 19. . Thereafter, the nozzle device 27 is connected to the opening 1.
4 to a position facing the substrate 18, and the spin table 17 is
The substrate 18 fixed to the spin table 17 is rotated at a low speed of pm. In accordance with this rotation, the required solution is supplied from the solution supply device 28 through the supply pipe 29,
A nozzle 24 corresponding to each solution in the nozzle device 27,
The solution is supplied to the nozzles 25 and 26, and the solution is discharged from the nozzles 24, 25 and 26.

When the necessary cleaning solution treatment is completed, the nozzle device 27 is moved to a position away from the opening 14, and the spin table 17 is continuously moved to, for example, 2000 rpm.
Draining and drying are performed by high-speed rotation at pm. At this time, the air blower 31 is driven, air is supplied to the air nozzle 30 through the supply pipe 32, and the air is jetted from the air nozzle 30 toward the rotation center of the substrate 18 rotating.

The role of the air nozzle 30 is to eliminate a situation in which when the substrate 18 is rotated at a high speed to perform the drying process, the centrifugal force is insufficient at the center of rotation of the substrate 18 and sufficient drainage and drying are not performed. By blowing air to the center of rotation, the center can be sufficiently dried. The air nozzle 30 can be omitted if the draining and drying processes are sufficiently performed only by the centrifugal force.

The solution supplied to the inside of the spin cup 11 is drained from a drain hole 21 to a drain device 23 through a drain pipe 22. If an exhaust device (not shown) is connected to the drain pipe 22 and the exhaust device is driven during the drying process, the exhaust device can function as an exhaust device. It is also possible to discharge.

Next, a specific example of a method of cleaning a substrate using the spin cup device will be described below.

In the first embodiment, first, the substrate 1 to be cleaned is
As 8, a glass substrate having a size of 300 mm × 400 mm is prepared and fixed to the spin table 17. In the solution supply device 28, three kinds of solutions of hydrogen peroxide solution, HF 0.5% solution and pure water are prepared. After the nozzle device 27 is moved to the upper part of the opening 14 of the spin cup 11, the spin table 17 is moved at 200 rpm by the motor 15.
m, and at first, the solution supply device 28
From the nozzle 24, the hydrogen peroxide solution is supplied from the nozzle 24 onto the rotating substrate 18 for 30 seconds.
Discharge for c. Then, subsequently, HF is supplied from the solution supply device 28 to the nozzle 25 for HF, and
The cleaning process is performed by discharging for 0 seconds.

After the completion of the cleaning process, the spin table 17 is rotated at 2000 rpm for 20 seconds at a high speed, and air is sprayed from the air nozzle 30 to the center of rotation of the substrate 18 to drain the substrate 18 and perform an intermediate drying process. I do. Subsequent to the intermediate drying process, pure water is supplied from the solution supply device 28 to the nozzle 26 for pure water while the spin table 17 is rotated at a low speed of 200 rpm. Then, a rinsing process is performed by discharging pure water for a period of 30 sec. At this time, the air blowing from the air nozzle 30 is stopped. After the rinsing process with the pure water is completed, the spin table 17 is rotated at a high speed of 2000 rpm for 30 seconds while the nozzle device 27 is moved from above the opening 14 and the air is again ejected from the air nozzle 30. Drain and dry.

In the case of this embodiment, the cleaning method of cleaning the substrate 18 is performed by the method of the cleaning process, the intermediate drying process, the rinsing process, and the final drying process described with reference to FIG. After the method, the number of foreign substances on the surface of the substrate 18 was measured. As a result, the number of foreign substances having a size of 1 μm or more was 10 or less, and only a very small number of remaining foreign substances were measured. Thus, good cleaning results could be obtained.

Next, a second embodiment will be described.
Substrate 18 used in this embodiment, the same size of the glass substrate as in Example depositing a SiO ₂ film to a thickness of 2000Å by PE-CVD method, further to the SiO ₂ film, the same After the a-Si film is deposited to a thickness of 1000 ° by the method, the a-Si film is formed into an island shape of 5 μm × 10 μm.
The substrate 18 was exposed at intervals of 100 μm and 50 μm, developed, and further etched using a CDE apparatus.

The substrate 18 is fixed on the spin table 17 and a solution supply device 28 is supplied with a hydrogen peroxide solution and HF.
Prepare a 0.5% solution and pure water. Then, the spin table 17 is rotated at a low speed of 200 rpm, and first, a hydrogen peroxide solution is supplied from the solution supply device 28 to the nozzle 24, and the solution is supplied from the nozzle 24 onto the rotating substrate 18.
Cleaning is performed on the substrate 18 by discharging it for only 10 seconds and then supplying HF from the solution supply device 28 and discharging it from the nozzle 25 onto the substrate 18 for only 10 seconds.

After the completion of the cleaning process, the spin table 1
7 is rotated at a high speed of 2000 rpm for 20 seconds, and air is sprayed from the air nozzle 30 to perform draining and intermediate drying. Continue spin table 1
7 is rotated at a low speed of 200 rpm, pure water is supplied to the nozzle 26 from the solution supply device 28, and the pure water is discharged from the nozzle 26 onto the surface of the substrate 18 for 30 seconds to perform a rinsing process. After this rinsing process is completed,
The spin table 17 is rotated at a high speed of 2000 rpm for 30 seconds, and air is jetted from the air nozzle 30 to perform draining and final drying of the substrate 18.

Also in this embodiment, a method of cleaning the substrate 18 through the processing steps described with reference to FIG. 1 is used. After the cleaning processing by this cleaning method is completed, a pattern inspection apparatus is used. When the foreign matter on the substrate 18 was inspected, foreign matter due to the mist of the chemical solution was not detected, and an extremely good cleaning result was obtained as in the first embodiment.

Next, a third embodiment will be described.
The substrate used in this example was a glass substrate having the same size as that of the above example, and a SiO ₂ film was formed on the glass substrate by PE-CVD.
And deposited on the SiO ₂ film.
A substrate 18 on which an a-Si film was deposited to a thickness of 1000 ° by the same method was used.

The substrate 18 is fixed on the spin table 17, and a hydrogen peroxide solution and HF
A 0.5% solution and pure water were prepared. Then, the spin table 18 is rotated at a low speed of 200 rpm, and first, a hydrogen peroxide solution is supplied from a solution supply device 28 to the nozzle 24, and 30 μm of water is supplied from the nozzle 24 onto the rotating substrate 18.
Then, HF is supplied from the solution supply device 28 and discharged from the nozzle 25 onto the substrate 18 for 60 seconds, thereby performing a cleaning process on the substrate 18. After the completion of the cleaning process, the spin table 17 is moved for 2000 seconds for 20 seconds.
A high-speed rotation is performed at rpm, and air is jetted from the air nozzle 30 to perform a draining process and an intermediate drying process.

Subsequently, the spin table 17 is set at 200 rpm.
At a low speed, pure water is supplied to the nozzle 26 from the solution supply device 28, and pure water is supplied from the nozzle 26 to the nozzle 26.
Rinsing treatment is performed by discharging to the surface of the substrate 18 for 0 seconds. After the rinsing process is completed, the spin table 17 is
The substrate 18 is rotated at a high speed of 3,000 rpm for 30 seconds and air is jetted from the air nozzle 30 to drain the substrate 18 and perform a final drying process.

After these processes were completed, foreign substances on the surface of the substrate 18 were measured. As a result, only a very small number of foreign substances having a size of 1 μm or more, ie, 10 or less, were measured. The result was able to be obtained.

Next, a fourth embodiment will be described. The substrate used in this example was a substrate 18 in which an Al film having a thickness of 8000 ° was formed on a glass substrate having the same size as that of the above example by sputtering.

The substrate 18 was fixed on the spin table 17, and two kinds of solutions of hydrochloric acid and pure water were prepared in the solution supply device 28. And spin table 17 for 200r
pm, and the solution supply device 28
Is supplied to the nozzle 24 from the nozzle 24, and is discharged from the nozzle 24 onto the rotating substrate 18 for only 10 seconds.
The substrate 18 is cleaned. After the completion of the cleaning process, the spin table 17 is rotated at a low speed while maintaining the same rotation speed, pure water is supplied from the solution supply device 28 to the nozzle 26, and the pure water is supplied from the nozzle 26 to the substrate 18 for 20 seconds.
Rinsing treatment is performed by discharging to the surface.

After the rinsing process is completed, the spin table 17 is rotated at a high speed of 2000 rpm for 30 seconds, and air is jetted from the air nozzle 30.
Draining and intermediate drying of the substrate 18 are performed. After the completion of the intermediate drying process, the spin table 17 is set at 200 rpm.
Then, the substrate 18 is rotated at a low speed, and pure water is again discharged from the nozzle 26 for 20 seconds to perform a second rinsing process on the substrate 18. After this rinsing process, the spin table 17
Is rotated at a high speed of 2000 rpm for 30 seconds, and air is jetted from the air nozzle 30 to drain the substrate 18 and perform a final drying process.

In the case of this embodiment, the method of cleaning the substrate 18 is performed by the cleaning method described in FIG. 2, which includes the cleaning process, the rinsing process, the intermediate drying process, the rinsing process, and the final drying process. After this final drying process,
As a result of counting foreign substances on the surface of the substrate 18 using a particle inspection apparatus, the number of foreign substances having a size of 1 μm or more was 10 or less, and a favorable cleaning effect was confirmed.

Table 2 summarizes the embodiments and effects of the above embodiments.

[Table 2] As shown in Table 2, it can be seen that a sufficient cleaning effect was obtained in each of the examples.

In the above description, each nozzle 24, 2
5 and 26 are described as a unitary nozzle device 27. However, these nozzles 24, 25 and 26 are formed as a single unit, and each of the nozzles 24, 25 and 26 has
It is also possible to connect the solution supply device 28 and the supply pipe 29 individually and use them independently.
Needless to say, 4, 25, and 26 can be increased or decreased according to the usage mode, and the air nozzle 30 can also be appropriately selected and employed. Further, the configuration of the spin cup 11 itself is not limited to this embodiment, and it goes without saying that various other modifications and applications are possible.

[0054]

As described above, according to the substrate cleaning method of the present invention, the intermediate cleaning step is introduced in the middle of the cleaning processing step and the final drying processing step, thereby avoiding the spin cleaning method. The probability of re-adhesion of the chemical solution to the substrate surface due to the scattering of mist generated by no airflow can be made as close to zero as possible during the final drying process, which increases the cleaning effect of the substrate and As a result, it is possible to improve the product quality and yield of the liquid crystal display device itself using this substrate.

Further, since there is no adhesion of the chemical solution and the amount of the chemical solution is very small even if it remains, the same spin cup is used for all of the cleaning process, the rinsing process, and the intermediate and final drying processes. Since the cleaning process can be performed, it is possible to provide a method for cleaning a substrate, which does not require separation of each process, can improve manufacturing efficiency, and can suppress capital investment.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a processing step for explaining one processing step example of a substrate cleaning method according to the present invention.

FIG. 2 is a process step explanatory view for explaining another example of the process steps in the method for cleaning a substrate according to the present invention.

FIG. 3 is a partially cutaway cross-sectional view schematically illustrating an example of a spin cup device used in the method for cleaning a substrate according to the present invention.

FIG. 4 is a schematic plan view showing the same spin cup device.

FIG. 5 is an explanatory view of a processing step for explaining a conventional method of cleaning a substrate.

[Explanation of symbols]

 17: Spin table 18: Substrate 24, 25, 26: Nozzle 27: Nozzle device 28: Solution supply device

Claims (4)

[Claims] 1. A cleaning processing step of mounting and fixing a substrate on a rotatable spin table, rotating the spin table, and discharging a cleaning liquid onto a cleaning surface side of the substrate to perform cleaning. A rinsing process of rinsing the rinsed substrate; and a drying process of drying the rinsed substrate, wherein an intermediate drying process is provided between the cleaning process and the drying process. Characteristic substrate cleaning method. 2. The substrate cleaning method according to claim 1, wherein the intermediate drying step is provided between the cleaning step and the rinsing step. 3. The method according to claim 1, wherein the rinsing process is divided into at least two processes, and the intermediate drying process is provided between the divided rinsing processes. 3. The method for cleaning a substrate according to item 2. 4. The method for cleaning a substrate according to claim 1, wherein the substrate is formed of a substantially rectangular substrate.