KR101108443B1 - Method of cleaning chamber using remote plasma - Google Patents

Abstract

The present invention comprises the steps of exciting the SF ₆ to the active species by applying RF power to the remote chamber; Introducing the SF ₆ active species into the process chamber; It provides a chamber cleaning method comprising the step of cleaning the inside of the process chamber using the SF ₆ active species.

According to the present invention, by using inexpensive SF ₆ instead of expensive NF ₃ , the inside of the chamber can be effectively cleaned even if the manufacturing equipment of the liquid crystal display is enlarged.

Cleaning, Remote Plasma, SF6, Channel

Description

Chamber cleaning method using remote plasma {Method of cleaning chamber using remote plasma}

1 is a view showing a conventional method of cleaning the inside of a chamber while the susceptor is raised

2 is a graph showing the relationship between flow rate and power when SF ₆ active species are used.

3 is a graph showing the relationship between the flow rate and the cleaning efficiency when using SF ₆ active species

4 is a view showing a state of cleaning the inside of the chamber in the susceptor is lowered in accordance with an embodiment of the present invention

* Description of the symbols for the main parts of the drawings *

10 process chamber 11 substrate

12: susceptor 13: shower head

14 gas inlet pipe 15 edge frame

16: cradle 17: channel

18: gate valve 19: exhaust port

20: remote chamber 30: RF power

40: cleaning gas supply unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning an interior of a process chamber for manufacturing a liquid crystal display (LCD) using a remote plasma, and more particularly, to generate a remote plasma using a higher RF power than a conventional method. It is about a method.

In general, in order to manufacture a liquid crystal display device, a thin film deposition process for depositing a dielectric material on a substrate, a photolithography process for exposing or hiding selected areas of the thin films using a photosensitive material, and removing the thin film of the selected area The etching process is patterned, and each of these processes is performed in a process chamber designed for an optimal environment for the process.

However, when the thin film deposition or etching process is repeatedly performed, the compound is deposited on an undesired place such as the inner wall of the process chamber or the edge of the susceptor.

Thus, the deposited compound is peeled off when a predetermined thickness or more, causing particles to act as a source of contamination inside the chamber.

In addition, since the electrical properties such as impedance inside the chamber are changed, in the apparatus for treating a substrate using plasma, the plasma density and thin film uniformity are adversely affected.

Therefore, in order to avoid this phenomenon, the inside of the process chamber should be periodically cleaned to remove the deposited pollutant.

Commonly used cleaning methods may be divided into dry cleaning using plasma and wet cleaning using a cleaning liquid. Dry cleaning is a method in which a cleaning gas is excited in a plasma state and then reacted with a compound deposited in a chamber.

Even with such dry cleaning, there is a limit to completely clean the inside of the chamber. Thus, wet cleaning is a method in which a person disassembles and directly cleans using a HF-based cleaning solution.

Although wet cleaning is very effective in cleaning, the equipment needs to be pumped for a long time to remove impurities and several dummy processes to normalize the process. It will greatly reduce.

Therefore, in general, only dry cleaning is performed, and wet cleaning is performed after several to several tens of dry cleanings.

Dry cleaning using plasma can be divided into in-situ cleaning and remote plasma cleaning. The former is a method of generating a cleaning plasma inside a process chamber which performs thin film deposition or etching process. Remote plasma cleaning is a method in which a cleaning gas is excited in a plasma state in a remote chamber separately installed outside the process chamber, and then the excited cleaning gas is introduced into the process chamber for cleaning.

In-situ cleaning is simple because no additional equipment is required, but in-situ cleaning may cause deterioration or peeling of the electrode surface due to ion bombardment caused by high frequency power applied to the cleaning gas.

In addition, the frequent discharge of the plasma damages the inner member of the chamber, there is a problem that the maintenance cycle must be shortened.

Therefore, despite the disadvantage of requiring a separate remote chamber and a separate RF power source, remote plasma cleaning has been continuously used.

1 illustrates a state in which a remote chamber 20 for remote plasma generation is connected to a process chamber 10 of a PECVD apparatus, and the process chamber 10 includes a susceptor for placing a substrate 11 therein. 12, a shower head 13 for injecting gas from the upper part of the susceptor 12, a gas inlet pipe 14 for connecting one end to the shower head 13 to inject a process gas or cleaning gas into the chamber, A channel 17 connected to the chamber sidewall for entering and exiting the substrate 11, a gate valve 18 installed in the middle of the channel 17, and an exhaust port 19 formed at the bottom of the chamber to discharge residual gas. do.

The susceptor 12 is moved up and down between the process position and the reference position (dotted line) while the substrate is placed on the upper surface by the driving means (not shown). The substrate 11 is transported through the channel 17 on the sidewall of the chamber while seated in a robot arm (not shown).

An edge frame 15 is located inside the chamber. The edge frame 15 is lifted by the susceptor 12 which rises as a thin plate-shaped square ring shape, and the edge of the substrate 11 placed in the susceptor. To prevent the gas from leaking.

When the susceptor 12 is lowered, the edge frame 15 is placed on the holder 16 fixed to the side wall of the chamber.

The other end of the gas inlet pipe 14 is connected to a remote chamber 20 for generating a remote plasma for cleaning, and the remote chamber 20 applies a cleaning gas supply unit 40 for supplying a cleaning gas and RF for applying RF power. The power source 30 is connected.

Looking at the conventional method for cleaning the interior of the process chamber 10 through the remote chamber 20 having such a configuration as follows.

First, when the susceptor 12 having the substrate 11 placed on the upper surface rises to a process position, the cleaning gas is supplied to the remote chamber 20 through the cleaning gas supply unit 40, and is applied by the RF power supply 30 applied thereto. The cleaning gas is excited with plasma active species. The cleaning gas is mainly NF ₃ is used.

The NF ₃ active species generated in the remote chamber 20 is injected into the process chamber 10 through the gas inlet pipe 14 and the shower head 13, so that the susceptor 12 or the shower head 13 may be discharged. Reacts with unnecessarily deposited compounds at edges, chamber sidewalls, etc. to separate them from the surface. In the process of introducing NF ₃ active species into the process chamber 10, a carrier gas such as N ₂ , He, Ar, etc. may be used.

After the cleaning is completed, the susceptor 12 is lowered to discharge the mixed gas such as cleaning gas and impurities through the exhaust port 13 through the edge of the susceptor 12.

However, this conventional remote plasma cleaning method has some problems as follows.

First, since the susceptor 12 is raised to the process position to clean only an extremely limited range of process chambers, impurities deposited in the rest of the chamber cannot be removed.

This is due to the fact that the process proceeds with the susceptor 12 raised so that the deposition is concentrated only on the top of the chamber and the cleaning gas is quite expensive.

However, even in the process region, deposition may occur in the exposed portion of the exhaust gas, and in particular, impurities P deposited inside the channel 17 into and out of the substrate 11 may be a direct source of contamination on the substrate. Therefore, a countermeasure is required.

Secondly, NF _{3, which} is used as a cleaning gas, is considerably expensive, which greatly increases the cost burden when used in large area LCD manufacturing equipment.

Third, NF ₃ has a high oxidizing power, and thus, there is a high risk of damaging the chamber member itself as well as a thin film unnecessarily deposited inside the chamber during the cleaning process.

The present invention is to solve this problem, to provide a remote cleaning method that can effectively clean the process chamber of the large-area LCD manufacturing apparatus.

In order to achieve the above object, the present invention comprises the steps of exciting the SF ₆ to the active species by applying RF power to the remote chamber; Introducing the SF ₆ active species into the process chamber; It provides a chamber cleaning method comprising the step of cleaning the inside of the process chamber using the SF ₆ active species.

The SF ₆ active species is introduced at a flow rate of 1 SLM for a volume of 10 to 12 dm ³ of the process chamber.

The RF power is characterized in that applied to the ratio of 1kW with respect to the volume 6 to 7 dm ³ of the process chamber.

The step of introducing the SF ₆ active species into the process chamber, the SF ₆ active species may be introduced with the carrying gas, wherein the SF ₆ active species is at least one carrier gas of He, N ₂ , Ar It is introduced with.

In another aspect, the present invention provides a method for cleaning the inside of a process chamber having a substrate stabilizer provided to be elevated in the interior, the process chamber is connected to the channel through which the substrate enters and outside the side wall using a remote plasma, Provided is a chamber cleaning method in which a remote plasma flows into an inside of the process chamber while the upper substrate and the inner space of the channel communicate with each other.

In this case, the remote plasma may be introduced into the process chamber while the upper surface of the substrate support is lower than the upper end of the channel.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

First embodiment

The first embodiment of the present invention provides a method for cleaning the interior of the process chamber using inexpensive SF ₆ active species instead of expensive NF ₃ .

That is, SF ₆ is excited as SF ₆ active species in a remote chamber outside the process chamber, and the excited SF ₆ active species is introduced into the process chamber to clean the inside of the chamber.

The SF ₆ active species combines with O ₂ to generate volatile compound SOx and combines with Si to generate volatile compound SiFx to remove impurities deposited in the chamber.

However, SF ₆ is to be supplied to the RF power of the big century, rather than SF ₆ NF ₃ in order to excite the active species due to the ionization energy is larger than NF _3.

The flow rate of introducing SF ₆ active species into the process chamber depends on the size of the process chamber. The table below shows the flow rate of SF ₆ active species according to the size of the substrate and should be applied to the remote chamber to generate such flow rate. The relationship between RF power to be shown is shown.

[table]

division 5th generation 6th generation 7th generation Board Size 1100mm * 1300mm 1500mm * 1850mm 1950mm * 2250mm SF ₆ flow rate 5-7 SLM 11-13 SLM 18-20 SLM RF power 13-16 kW 21-24 kW 33-36 kW

For example, a process chamber for processing a 6th generation substrate (1500 mm * 1850 mm), for example, the flow rate of SF ₆ active species introduced into the chamber is 11 to 13 standard litter per minute (SLM). RF power of 21 to 24 kW should be applied to the remote chamber.

Figure 2 shows the relationship between the flow rate of the SF ₆ active species and RF power based on the experimental results, in order to generate a flow rate of 6 SLM, RF power of about 15 kW should be supplied, and to generate a flow rate of 12 SLM It can be seen that RF power of about 22 kW should be supplied, and RF power of about 35 kW should be supplied to generate a flow rate of about 20 SLM.

On the other hand, if the data is converted based on the volume of the process chamber instead of the size of the substrate, SF ₆ active species should be introduced at a flow rate of 1 SLM for the process chamber volume 6-7 dm ³ , RF power is the process chamber A power of 1 kW shall be applied for a volume of 10-12 dm ³ .

In addition, if the volume of the process chamber is the same condition, the cleaning efficiency can be increased by increasing the flow rate of SF ₆ active species, the above table is based on the cleaning efficiency of 4500 kW / min.

According to the experiment, the relationship between the flow rate of the SF ₆ active species and the cleaning efficiency in the process chamber using the fifth generation substrate is shown in FIG. 3.

That is, the flow rate of the SF ₆ active species is 3000 kW / min at 3 SLM, 4500 kW / min at 6 SLM, and 5000 kW / min at 7 SLM. As the flow rate increases, the cleaning efficiency increases.

Meanwhile, when the SF ₆ active species is introduced into the process chamber, it can be introduced using a carrier gas such as He, N ₂ or Ar as in the conventional case.

In this way, replacing the cleaning gas with SF ₆ can reduce the cost burden due to the cleaning gas even if the volume of the process chamber increases as the size of the substrate increases.

Second embodiment

4 illustrates a chamber cleaning method according to a second embodiment of the present invention, in which the upper space of the susceptor 12 and the inside of the channel 17 are disposed so that the cleaning gas may reach the inside of the channel through which the substrate enters and exits. Characterized in that the cleaning gas is injected in the communication state.

That is, unlike the conventional method of raising the susceptor 12 to the process position and then spraying the cleaning gas to clean only the process area, the susceptor 12 is lowered below the process position to extend the cleaning gas to the entire chamber. It was made.

Therefore, the susceptor 12 may be located at any height between the reference position at which the substrate is exchanged and the position just before the upper surface of the susceptor 12 touches the edge frame 15.

However, in order for the cleaning gas to be sufficiently supplied into the channel 17 to remove particles, the upper space of the susceptor 12 and the inside of the channel 17 must be sufficiently communicated, so that the upper surface of the susceptor 12 is connected to the channel 17. It is desirable to be at a position lower than the top of the).

In the second embodiment of the present invention, since the cleaning area is increased by lowering the susceptor 12 to clean the entire chamber, the second embodiment of the present invention has been described in the first embodiment to reduce the cost burden due to expensive NF ₃ . It is preferable to use SF ₆ as the cleaning gas.

The flow rate of the SF ₆ active species is determined by referring to the relationship between the flow rate and power, the flow rate and the cleaning efficiency, and the volume and flow rate of the process chamber or the RF power.

According to the present invention, by using inexpensive SF ₆ instead of expensive NF ₃ , the inside of the chamber can be effectively cleaned even if the manufacturing equipment of the liquid crystal display is enlarged.

Claims (7)

Process chamber; Connecting the process chamber and applying RF power to the remote chamber to excite SF ₆ as the active species; Combining the SF ₆ active species with a carrier gas in the remote chamber and introducing the SF ₆ into the process chamber; And The SF ₆ active species cleans the inside of the process chamber by generating SOx bonded to O ₂ and SiFx bonded to Si; Chamber cleaning method comprising a The method of claim 1, The SF ₆ active species is introduced into the chamber at a flow rate of 1 SLM for a volume of 10 to 12 dm ³ . The method of claim 1, Wherein the RF power is applied at a rate of 1 kW relative to a volume of 6 to 7 dm ³ of the process chamber. delete The method of claim 1, The SF ₆ active species is a chamber cleaning method that is introduced with at least one carrier gas of He, N ₂ , Ar In the method for cleaning the interior of the process chamber having a substrate support that is installed to be elevated in the interior, the channel is connected to the sidewall of the substrate by using a remote plasma, Combining SF ₆ active species with a carrier gas into the process chamber from a remote chamber in a state where the substrate stabilizer is positioned so that the upper space of the substrate stabilizer and the internal space of the channel communicate with each other; And The SF ₆ active species cleans the inside of the process chamber by generating SOx bonded to O ₂ and SiFx bonded to Si; Chamber cleaning method comprising a The method of claim 6, A chamber cleaning method in which a remote plasma flows into the process chamber while the upper surface of the substrate support is lower than the upper end of the channel.

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