WO2003005427A1

WO2003005427A1 - Processing system and cleaning method

Info

Publication number: WO2003005427A1
Application number: PCT/JP2002/006734
Authority: WO
Inventors: Junichi Arami; Takashi Akahori; Risa Nakase
Original assignee: Tokyo Electron Limited
Priority date: 2001-07-03
Filing date: 2002-07-03
Publication date: 2003-01-16
Also published as: JP2003017416A

Abstract

A processing system capable of performing dry cleaning by leading cleaning gas activated by plasma in an activator (110) into a processing chamber (101), wherein exhaust gas from the processing chamber (101) passes through a circulation line (128), is slowed down by a cryotrap (115) formed of a temperature trap utilizing a difference in steam pressure, and is re-used for cleaning.

Description

Description processing system and cleaning method

Technical field

The present invention relates to a processing system and a cleaning method capable of performing efficient cleaning at low manufacturing cost.

Background art

It is known that a substrate such as a semiconductor wafer is subjected to a desired process using various process gases in a chamber to form a thin film, perform etching, and the like. In such a process, it is necessary to clean the inside of the chamber after repeating the process a plurality of times.

For example, a chemical vapor deposition method (Chemical Vapor Deposition: CVD), a physical vapor deposition method (Physical Vapor Deposition: PVD), or the like is used for a thin film forming process on a semiconductor substrate. In such a thin film forming process, film deposition occurs not only on the substrate but also throughout the chamber. For this reason, the film deposited on the chamber wall or the like is peeled off and is taken into the deposited film on the substrate or adheres to the surface of the deposited film. This leads to defects in the manufactured device, causing problems such as a decrease in device yield and deterioration in device characteristics.

Further, when etching is performed on a substrate or the like on which a thin film is formed as described above, dry etching or the like is performed in which an etching gas is introduced into a processing chamber to perform etching. In this dry etching, substances generated by the etching adhere and deposit everywhere in the chamber. These products are composed of, for example, by-products generated by etching.

As the etching or etching repeats, the deposited or deposited film becomes It grows gradually on the surface of each part in Yamba, and the film thickness becomes thick. The thick film eventually peels off and causes particles, and also deteriorates the reproducibility of the etched shape.

As described above, in processes such as thin film formation and etching using a process gas, it is necessary to remove and clean a film adhered or deposited on unnecessary portions of the chamber other than the substrate surface. As a method of cleaning such a chamber, dry cleaning is performed in which an etching gas is flowed into the chamber to etch a deposited film.

As a gas (etching gas) used for cleaning, a fluorine-based or chlorine-based gas is used. By activating this gas, for example, as plasma, active species such as fluorine radicals are generated and reacted with the deposited film in the chamber to remove them.

By the way, dry cleaning is usually performed in a vacuum state of a chamber for the purpose of extending the life of active species such as radicals. During cleaning, the chamber is evacuated at a high speed, and the residence time of the cleaning gas in the chamber is very short.

For this reason, the reaction rate of the cleaning gas introduced into the chamber with respect to contaminants in the chamber is usually as low as about 10%, and most of the cleaning gas is discarded without being used. However, gases used for cleaning, such as nitrogen trifluoride, are generally expensive and contribute to an increase in manufacturing costs.

As described above, the conventional dry cleaning has a problem that cleaning efficiency is low and manufacturing cost is high due to low utilization efficiency of the cleaning gas. Disclosure of the invention

In order to solve the above problems, the present invention provides an efficient cleaning method at a low manufacturing cost. It is an object of the present invention to provide a processing system and a cleaning method that can perform the cleaning.

Another object of the present invention is to provide a processing system and a cleaning method with high cleaning gas utilization efficiency.

In order to achieve the above object, a processing system according to a first aspect of the present invention includes: a processing chamber (101) for performing a predetermined processing on an object;

A cleaning gas line (111) for introducing a cleaning gas for cleaning the processing chamber (101) into the processing chamber (101); and an exhaust device (110) for exhausting the cleaning gas from the processing chamber (101). 109)

The exhaust gas (109) and the cleaning gas line (111) are provided so as to be connected to each other, and the cleaning gas exhausted by the exhaust device (109) is guided to the processing chamber (101). A circulation line (128);

The Power ^¾ that consists of.

In the processing system having the above-described configuration, the circulation line (128) may include a trap device (115) for selectively trapping a reaction product gas generated by cleaning in the tally-jung gas.

In the processing system having the above configuration, the trap device (115) traps the reaction product gas based on, for example, a difference in vapor pressure between the reaction product gas and the cleaning gas.

The processing system having the above configuration may further include a pressure adjusting device (107) for adjusting the pressure of the circulation line (128) to a predetermined pressure.

In the processing system having the above configuration, for example, the cleaning gas is composed of nitrogen trifluoride.

The processing system having the above configuration may further include an activator (110) for activating and introducing the clean Jung gas into the processing chamber (101). The processing system having the above configuration further includes a processing chamber (101). An activator (130) for activating the cleaning gas may be provided. In order to achieve the above object, a cleaning method according to a second aspect of the present invention is a cleaning method for cleaning a processing chamber (101) for internally performing a predetermined process on a target object,

Cleaning by introducing a cleaning gas into the processing chamber (101);

An exhaust step of exhausting the cleaning gas from the inside of the processing chamber (101);

Guiding the exhausted cleaning gas into the processing chamber (101);

Is provided.

The cleaning method having the above configuration may include a trapping step of selectively trapping a reaction product gas generated by the cleaning in the exhausted cleaning gas.

In the cleaning method having the above-described configuration, in the trapping step, for example, the reaction product gas is trapped based on a difference in vapor pressure between the reaction product gas and the cleaning gas.

The cleaning method having the above configuration may further include a step of adjusting the pressure of the circulation line (128) to a predetermined pressure.

The cleaning method having the above configuration may further include a step of activating and introducing the cleaning gas into the processing chamber (101).

The cleaning method having the above configuration may further include a step of activating the cleaning gas supplied into the processing chamber (101). BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a configuration of a processing system according to an embodiment. FIG. 2 is a diagram showing a vapor pressure curve of each reaction product contained in the gas after cleaning.

FIG. 3 is a diagram showing a configuration of a processing system according to another embodiment of the present invention.

5 Best mode for carrying out the invention

A processing system according to an embodiment of the present invention will be described below with reference to the drawings. In this embodiment mode, a processing chamber in which a silicon film such as a silicon oxide film (SiO 2) or a silicon fluoride film (Si OF) is formed is made of nitrogen trifluoride (NF ₃ ) and argon. The case of cleaning using the mixed gas of (A r) will be described as an example.

FIG. 1 shows a configuration of a processing system 100 according to an embodiment of the present invention.

As shown in FIG. 1, the processing system 100 includes a processing chamber 101, a turbo molecular pump 104, a dry pump 105, an exclusion device 106, and an activator 110. , A cleaning gas supply line 111, a circulation line 128, and 15.

The processing chamber 101 is composed of a sealable container made of aluminum or the like. The processing chamber 101 is connected to a process gas introduction line 112. An object to be processed such as a semiconductor wafer is placed in the processing chamber 101. The process gas supplied from the process gas introduction line 112 forms a silicon film such as a silicon oxide film.

The turbomolecular pump 104 is connected to the exhaust side of the processing chamber 101 via a gate valve 102 and a pressure regulating valve 103. Further, the dry pump 105 is connected to the exhaust side of the turbomolecular pump 104 via a valve 124 and a pressure gauge 126. Furthermore, the exclusion device 106 is connected to the exhaust side of the dry pump 125505.

The turbo molecular pump 104 exhausts the processing chamber 101 and adjusts the pressure. The inside of the processing chamber 101 is maintained at a degree of vacuum controlled by the valve 103. The dry pump 105 is a roughing pump, and the inside of the system is set to a degree of vacuum at which the turbo molecular pump 104 and the molecular drag pump 109 can operate. Here, the turbomolecular pump 104 and the dry pump 105 are oil-free pumps, which prevent oil molecules from entering the system. Note that the processing chamber 101 may be evacuated directly by the turbomolecular pump 104 without providing the dry pump 105.

The elimination device 106 detoxifies impurities in the gas passing therethrough and discharges them to the atmosphere. The exclusion device 106 is connected to a dry pump 105 and a cryotrap 115 described later. The elimination device 106 eliminates impurities in the process gas and the cleaning gas.

The cleaning gas supply line 111 is connected to the activator 110 via a valve 117. The activator 110 is connected to the processing chamber 101. The cleaning gas supply line 111 is connected to a cleaning gas source (not shown), and supplies a cleaning gas to the activator 110. As described above, in this example, the cleaning gas is composed of a mixed gas of NF ₃ and Ar.

The activator 110 activates the cleaning gas (NF ₃ ) and supplies the generated cleaning species to the processing chamber 101. The activator 110 selectively supplies, in particular, fluorine radicals in the generated plasma to the chamber 101. The activator 110 generates a high-density plasma having a high plasma density, such as an ECR (Electron Cyclotron Resonance) plasma or an inductively coupled plasma (ICP). For example, when generating ECR plasma, microwaves of 2.45 GHz are applied to generate a region in the vacuum discharge chamber that satisfies the ECR condition of 875 gauss, and gas molecules in this region are converted to plasma. You. The activator 110 is equipped with a filter and the like, and radicals (fluorine) in the plasma Radicals).

For example, the process chamber 1 0 1 S i 0 ₂ is deposited is removed as shown in the chemical formula of the following by fluorine radicals. That, S i O ₂ forms the fluorine radicals (F *) and reacted with 4 fluorinated silane (S i F _4), and oxygen (0 _2), the. (5) Since all of the reaction products are gases under the cleaning conditions, they are released to the outside of the processing chamber 101 together with the exhaust gas. In this way, the cleaning proceeds, and the deposited film in the chamber 101 is removed. In addition, as a by-product, in addition to tetrafluorosilane and oxygen, fluorine (F ₂ ) which is a polymer of a fluorine radical, hydrogenated fluorine (HF), and the like are included.

10 S i O _z + 4 F * → S i F 4 + O 2

The circulation line 128 is composed of a molecular drag pump 109 and a cryotrap 115. The circulation line 128 is connected to the processing chamber 101 separately from the line connected to the turbomolecular pump 104, and is connected to the intake side of the activator 110. As described later, the circulation line 1152 functions as a line for reusing the cleaning gas once used.

The molecular drag pump 109 is connected to the processing chamber 101 via a valve 113 and a pressure regulating valve 114. The pressure of the processing chamber 101 is adjusted by the pressure adjusting valve 114. On the exhaust side of molecular drag pump 109

The valve 20 is provided with a valve 108 and connected to the dry pump 105 via a pressure regulating valve 107. The pressure in the circulation line 128 is adjusted by the pressure adjusting valve 107. The exhaust side of the valve 108 is connected to the intake side of the cryotrap 115 via a valve 120.

The molecular drag pump 10 9 is a turbo molecular pump 10 4

25, too, has high intake limit pressure and critical back pressure, so it can provide sufficient pressure to the circulation system. Here, the critical back pressure means the maximum outlet pressure of the pump. Also, The recursive drag pump 109 is an oil-free pump, and prevents oil molecules from being mixed into the system.

The cryotrap 115 is a gas trap. The cryotrap 115 traps, as a liquid, a predetermined component of the gas passing therethrough due to a difference in vapor pressure depending on the temperature. The cryotrap 115 traps impurities contained in the cleaning gas and purifies the cleaning gas so that it can be reused. The cryotrap 115 has a liquid tank (not shown), and trapped impurities are stored in the liquid tank.

More specifically, the inside of the cryotrap 115 is set at a predetermined pressure so that the cleaning component (NF ₃ ) in the gas is a gas and the impurity component is liquefied. Thus, while the cleaning component passes as a gas, the impurity component is trapped as a liquid.

In this example, a silicon film (S I_〇 ₂ film, S i OF film etc.) Kuriyungu processing Chiya N'noku 101 for performing formation process in the cleaning gas composed of NF _3, A r. In this case, the gas that has passed through the processing chamber 101 contains reaction products such as SiF ₄ , F ₂ , and HF in addition to NF ₃ and Ar.

FIG. 2 shows the vapor pressure curves of the components in the cleaning exhaust gas described above. Referring to FIG. 2, the pressure of circulation line 128 is set to 0.1 Pa (l OTo rr) to 1 Pa (10 OTo rr), and the temperature of cryotrap 115 is set to about 140 ° C (see FIG. by setting the hatched portion) and, HF which is an impurity, S i F ₄ are trapped in the _{_{liquid, NF 3, F 2, a}} r passes as a gas. In this way, the cleaning gas once used by the cryotrap 115 is purified.

The cryotrap 115 is connected to the activator 110 via a valve 118. The cleaning gas that has passed through the cryotrap 115 is activated again by the activator 110 and is introduced into the processing chamber 101. In this way, when the cleaning gas is reused, the valves 118 and 12 are open. At this time, the valve 1 21 is closed.

The liquid tank (not shown) of the cryo-trap 1 1 5, therefore the passage of the cleaning gas, the trap of such S i F ₄ Yuku been accumulated, cryotrap 1 1 5 must be periodically regenerated. Here, the regeneration of the trap refers to elevating the temperature inside the trap, vaporizing the SiF ₄ or the like trapped as a liquid, and removing the liquid from the trap.

Regeneration of the cryotraps 115 is performed, for example, when cleaning is performed a predetermined number of times. When the cryotrap 115 is regenerated, the valves 118 and 120 are closed and the valve 121 is opened. The cryotrap 115 is connected to the dry pump 125 via the valve 121. Since the trapped impurities are combustible gases, they are removed by a removal device 106 connected to a dry pump 125 to avoid mixing with the process gas.

Hereinafter, the cleaning operation of the processing system 100 according to the present embodiment will be described. After the predetermined processing in the processing chamber 101 is completed, the flow of the process gas from the process gas introduction line 112 is stopped, and the gate valve 102 and the valve 124 are closed. After the processing is completed in this way, the cleaning operation is started.

First, the valves 108 and 113 are opened, and the inside of the processing chamber 101 is set to a predetermined degree of vacuum by the molecular drag pump 109. Subsequently, the valve 1 17 is opened, and the cleaning gas is supplied from the cleaning gas supply line 113. At this time, the pressure in the processing chamber 101 is set lower than the pressure in the circulation line 128 by the pressure regulating valves 114, 107, and the cleaning gas is set in the circulation line 128. Flows to

The cleaning gas that has entered the activator 110 is activated therein and then introduced into the processing chamber 101. Processing chamber 1 0 active species introduced in the gas in one (fluorine radicals, etc.) forces the processing chamber 1 0 engaged film and forming deposited inside the 1, decomposing it into gaseous components such as S i F ₄ And remove. These reaction products are The gas is exhausted from the processing chamber 101 together with unreacted NF ₃ and Ar.

The gas discharged from the processing chamber 101 flows to the circulation line 128 via the valves 113, 108. The gas further flows through a circulation line 128 set at a predetermined pressure, and reaches a cryotrap 115. The pressure in the circulation line 128 is set to, for example, 0.1 P a (l OTo rr) to: IP a (l O O rr), and the cryotrap 115 is set to a predetermined temperature, for example, _ It is set around 140 ° C.

By setting the pressure of the circulation line 128 and the temperature of the cryotrap 115 to the above values, the cleaning components such as NF ₃ can be passed while the impurities in the gas (S i F ₄ Etc.) can be selectively trapped as a liquid. Therefore, the gas that has passed through the cryotrap 115 is purified and becomes a reusable cleaning gas.

The cleaning gas purified by the cryotrap 115 is mixed with a new cleaning gas supplied from the cleaning gas supply line 113, activated by the activator 110, and supplied to the processing chamber 101 again.

As described above, in the processing system 100 of the present invention, when performing dry cleaning of the processing chamber 101, the cleaning gas is circulated and used. For this reason, in general, expensive cleaning gas can be used with high utilization efficiency without being discarded in one use. In addition, since the cleaning gas is used after removing impurities in the cryotrap 115, a reduction in cleaning efficiency and a deterioration in the quality of the cleaning can be avoided.

The present invention is not limited to the above embodiment, and various modifications and applications are possible.

In the above embodiment, the cryotrap 115 is a temperature trap that separates the cleaning component and the impurity component from each other based on the difference in vapor pressure. However, any trap that can trap impurities can be used. In the above embodiment, a mixed gas of NF ₃ and Ar is used as the cleaning gas. However, the substance used for the cleaning gas is not limited to this. For example, instead of NF _3, it can be used _{_{_{CF 4, C 2 F 6,}}} SF 6, fluorine-based gas of NF 3 and the like, halogen-based gas of chlorine-based gas such as C 1 _2, BC 1 _4.

Further, instead of Ar, another inert gas, for example, Ne, Xe, N ₂ or the like can be used.

In the above embodiment has been described for the case of removing the silicon film such as S I_〇 _2, S i OF. However, the present invention is not limited to the above example, and the present invention can be suitably applied to removing any other deposited film such as a SiC film, a SiN film, a SiOC film, a CF film, and the like. .

Even when the present invention is applied to other gas types and other film types as described above, the same effects as in the present embodiment can be obtained by using traps and trap conditions capable of effectively removing cleaning by-products. can get.

For example, if carbon dioxide (co ₂ ) is generated during cleaning using a film type containing carbon (C) (such as SiC), the vapor pressure curve of CO ₂ under the same conditions as in the above example is shown in Figure 2. This shows that CO ₂ can be effectively removed.

Further, in the above embodiment, the cleaning gas is activated outside the processing chamber 101 to generate plasma, and the plasma is generated and introduced into the processing chamber 101. However, the method of activating gas is not limited to plasma, and any method may be used. Further, the cleaning gas may be activated inside the processing chamber 101. In this case, for example, as shown in FIG. 3, an activator 130 such as a plasma generation mechanism may be provided in the processing chamber 101.

In the above embodiment, an example in which the present invention is applied to a film forming apparatus has been described. However, the present invention is not limited to this, and can be applied to other processing apparatuses such as an etching apparatus, and further to any other processing apparatus that performs dry cleaning. Industrial applicability

INDUSTRIAL APPLICATION This invention is usefully applicable to various processing apparatuses, such as a semiconductor manufacturing apparatus and a liquid crystal display device.

The present invention is based on Japanese Patent Application No. 2001-201946 filed on Jul. 3, 2001, and includes the specification, claims, drawings and abstract thereof. The disclosure in the above application is incorporated herein by reference in its entirety.

Claims

The scope of the claims

1. a processing chamber (101) for performing predetermined processing on an object to be processed;

A cleaning gas line (111) for introducing a cleaning gas for cleaning the processing chamber (101) into the processing chamber (101); and an exhaust device for exhausting the cleaning gas from the processing chamber (101). (109) and

A processing system, comprising a power.

2. The circulation line (128) includes a trap device (1 15) for selectively trapping a reaction product gas generated by cleaning in the cleaning gas. The processing system as described.

3. The trap device (115) traps the reaction product gas based on a difference in vapor pressure between the reaction product gas and the cleaning gas. Item 3. The processing system according to Item 2.

4. The processing system according to claim 1, further comprising a pressure adjusting device (107) for adjusting the pressure of the circulation line (128) to a predetermined pressure.

5. The processing system according to claim 1, wherein the cleaning gas is composed of nitrogen trifluoride.

6. The processing system according to any one of claims 1 to 5, further comprising an activator (110) for activating and introducing the cleaning gas into the processing chamber (101). .

7. Further, the cleaning gas supplied into the processing chamber (101) is provided. The processing system according to any one of claims 1 to 5, further comprising an activator (130) for activating the source.

8. A cleaning method for cleaning a processing chamber (101) for internally performing a predetermined process on a workpiece,

5 cleaning by introducing a cleaning gas into the processing chamber (101);

Guiding the exhausted cleaning gas into the processing chamber (101);

A cleaning method, comprising:

9. The cleaning method according to claim 8, wherein the cleaning method includes a trapping step of selectively trapping a gas of a reaction product generated by cleaning in the exhausted cleaning gas. .

15 10. In the trapping step, the reaction product gas is trapped based on a difference in vapor pressure between the reaction product gas and the cleaning gas. The cleaning method described.

11. The cleaner according to claim 8, further comprising a step of adjusting the pressure of the circulation line (128) to a predetermined pressure.

20 ninging methods.

12. The cleaning method according to any one of claims 8 to 11, further comprising a step of activating and introducing the cleaning gas into the processing chamber (101).

13. The method according to claim 8, further comprising a step of activating the cleaning 25 gas supplied into the processing chamber (101).

The cleaning method according to item 1.