JP2005142596A - Method of cleaning semiconductor manufacturing apparatus and method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of cleaning a semiconductor manufacturing apparatus, where in forming a semiconductor thin film, a fluorine gas is prevented from leaking out of a substrate support electrode (electrostatic chuck) on which a substrate is placed; the semiconductor thin film can be formed without reducing a deposition temperature around the substrate (wafer); defects such as the abnormal thickness of a film, a failure of etching and film peeling are prevented, and also to provide a method of manufacturing the semiconductor device. <P>SOLUTION: At a waiting time for forming a semiconductor thin film before a wafer (substrate) is introduced into a chamber 104, a fluorine reduction processing is performed in the chamber using hydrogen gas and inert gas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cleaning method of a semiconductor manufacturing apparatus such as a plasma CVD (Chemical Vapor Deposition) apparatus, and more specifically, for example, a silicon oxide film containing fluorine (F) such as an interlayer insulating film of a semiconductor device (hereinafter referred to as “ The present invention relates to a method for cleaning a semiconductor manufacturing apparatus and a method for manufacturing a semiconductor device.

  The semiconductor device manufacturing process includes a plasma CVD process in which a semiconductor thin film is formed on a substrate. In this film forming process, a substrate is placed on an electrostatic chuck provided in the reaction furnace, a reaction gas is supplied into the reaction furnace, high frequency power is applied between a pair of electrodes to generate plasma, The reaction gas molecules are decomposed by plasma to form a semiconductor thin film on the substrate surface.

  By repeating such a film formation process, the semiconductor thin film adheres and deposits also on the surface of the reactor and electrodes of the plasma CVD apparatus, so that the film attached and deposited on these reactors and electrodes peels off during the film formation process. As a result, the film adheres to the substrate during the film forming process and is contaminated.

  Therefore, in recent years, as a cleaning method in the reactor of the plasma CVD apparatus, as in the film formation, a fluoride-based cleaning gas is used, and plasma is applied to generate F atoms, which are applied to the reactor inner wall and electrodes. A method of cleaning the deposited / deposited film has been performed. In addition, fluorine atoms generated during cleaning using this fluoride-based cleaning gas are adsorbed and remain on the inner wall and electrode of the reactor, and in order to reduce this, F atoms are reduced using fluorine reducing gas. Then, residual fluorine atoms in the furnace are reduced and removed.

  Specifically, for example, in JP-A-7-201738, a fluorine reducing gas is supplied into a reaction furnace and an active species such as a radical or ion of a nitride compound is supplied. A cleaning method is disclosed in which residual fluorine components are reduced and removed by acting on the liquid.

JP-A-9-249976 discloses that NF ₃ , CF ₄ , C ₃ F ₈ , C ₂ F ₆ , and ClF ₃ are used as the fluoride-based cleaning gas, and O ₂ , H ₂ as the fluorine reducing cleaning gas. And a cleaning method using at least one selected from an inert gas is disclosed.

Further, in JP-A-10-147877, an inert gas (nitrogen gas as required) is supplied into the reaction furnace as a fluorine reducing gas after or during cleaning using a fluorine-based cleaning gas, A cleaning method for reducing and removing the fluorine component is disclosed.
JP-A-7-201738 Japanese Patent Laid-Open No. 9-249976 Japanese Patent Laid-Open No. 10-147877

  In the cleaning method as proposed above, a ceramic cover having the same shape as the substrate (wafer) is usually placed on the electrostatic chuck to protect the surface of the electrostatic chuck provided in the reactor of the plasma CVD apparatus. To do. Then, a fluoride-based cleaning gas is supplied into the reaction furnace and plasma is generated to remove the SiO film in the reaction furnace. After this cleaning is completed, the ceramic cover is left on the cleaning chuck, A fluorine reducing gas is supplied to the plasma and plasma is generated to reduce and remove residual fluorine atoms in the reaction furnace.

  Thus, during the cleaning of the plasma CVD apparatus, the ceramic cover is placed on the electrostatic chuck to protect the surface of the electrostatic chuck.

  However, under the conventional cleaning conditions, a gap between the ceramic cover and the electrostatic chuck is generated due to warping of the ceramic cover, and a fluoride-based cleaning gas enters the gap and the fluorine component is adsorbed on the surface of the electrostatic chuck. There is a problem. The residual fluorine component adsorbed on the surface of the electrostatic chuck is not sufficiently reduced and removed even by the treatment with the fluorine reducing gas. Therefore, the residual fluorine component is detached from the surface of the electrostatic chuck (hereinafter referred to as F degassing) when the semiconductor thin film is formed after cleaning. However, there is a problem that the film forming temperature around the substrate (wafer) is lowered and defects such as an abnormal film thickness, defective etching, and film peeling occur, and improvement is desired. In particular, this phenomenon is an important problem because it occurs remarkably when an FSG film is formed.

  Accordingly, an object of the present invention is to solve the conventional problems and achieve the following object. That is, the object of the present invention is to prevent F degassing from the substrate support electrode (electrostatic chuck) on which the substrate is disposed during the formation of the semiconductor thin film, and to form the semiconductor thin film without lowering the film forming temperature around the substrate (wafer). It is possible to provide a method for cleaning a semiconductor manufacturing apparatus and a method for manufacturing a semiconductor device that can prevent defects such as an abnormal film thickness, defective etching, and film peeling.

The above problem is solved by the following means. That is,
A cleaning method for a semiconductor manufacturing apparatus of the present invention is a cleaning method for a semiconductor manufacturing apparatus in which a substrate is disposed on a substrate support electrode provided in a reaction furnace, and a semiconductor thin film is formed on the substrate,
When waiting for semiconductor thin film formation before carrying the substrate into the reactor,
A cleaning process for generating plasma after supplying hydrogen gas and inert gas into the reaction furnace is provided.

  In addition, the semiconductor device manufacturing method of the present invention includes a substrate placed on a substrate support electrode provided in the reaction furnace after being cleaned by the semiconductor manufacturing apparatus cleaning method of the present invention. After the source gas is supplied to the substrate, plasma is generated to perform a step of forming a semiconductor thin film on the substrate.

  As described above, according to the present invention, during the formation of a semiconductor thin film, F degassing from the substrate support electrode (electrostatic chuck) on which the substrate is disposed can be prevented, and the semiconductor film can be formed without lowering the film formation temperature around the substrate (wafer). A thin film can be formed, and a method for cleaning a semiconductor manufacturing apparatus and a method for manufacturing a semiconductor device that can prevent defects such as abnormal film thickness, defective etching, and film peeling can be provided.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In addition, what has the substantially same function is attached | subjected and demonstrated through the whole figure, and the description may be abbreviate | omitted depending on the case.

(Reference example)
FIG. 1 is a schematic configuration diagram illustrating a semiconductor manufacturing apparatus according to a reference example.

  A semiconductor manufacturing apparatus shown in FIG. 1 includes an injector 106 and an electrostatic chuck 108 (lower electrode) in a chamber 104 (reactor) sealed by a main body 100 and a pelger 102 (ceramic dome) which is an upper electrode. The substrate support electrode) is disposed in the plasma CVD apparatus, and the source gas is supplied from the injector 106 into the chamber 104 held in vacuum by evacuation from an exhaust port (not shown) disposed in the apparatus main body 100. For example, a plasma having a frequency of 400 kHz is generated from the pelger 102 and a plasma having a frequency of 13.56 kHz is generated from the electrostatic chuck to form a film. In addition, the semiconductor manufacturing apparatus shown in FIG. 1 includes an injector 107 that supplies a fluoride-based cleaning gas into the chamber 104.

  In this reference example, as a cleaning method of the semiconductor manufacturing apparatus shown in FIG. 1, first, a ceramic cover 110 (insulating cover) for protecting the surface of the electrostatic chuck 108 on the electrostatic chuck 108 disposed in the chamber 104. ) Is applied, the ceramic cover 110 is brought into close contact with the surface of the electrostatic chuck 108 by applying a voltage of, for example, about 600 V to the electrostatic chuck 108. As a method of placing the ceramic cover 110 in close contact with the electrostatic chuck 108, there is a method of clamping with a clamp ring in addition to a method of applying a voltage of about 600 V to the electrostatic chuck.

Next, the pressure in the chamber 104 is set to, for example, 0.1333 to 1.333 Pa (1) while supplying NF ₃ gas as a fluoride-based cleaning gas, for example, 100 to 1000 sccm from the injector 107 disposed in the chamber 104. A pressure of about 10 mTorr) is maintained.

Then, plasma with a frequency of, for example, 13.56 MHz is generated from the bell jar 102 which is the upper electrode at an output of 1000 to 1500 W, and NF ₃ gas is plasma-excited to generate F radicals, which are deposited and deposited on the inner wall of the chamber 104. The deposit is removed by reacting with a deposit such as a film to generate a volatile compound such as SiF ₄ and exhausting it from the chamber 104.

Next, while supplying H ₂ gas, for example, 200 to 1000 sccm as a fluorine reducing gas into the chamber 104, the pressure in the chamber 104 is maintained at a pressure of about 0.1333 to 1.333 Pa (1 to 10 mTorr), for example. To do.

Then, plasma with a frequency of, for example, 13.56 MHz is generated from the bell jar 102, which is the upper electrode, with an output of 500-1500 W to excite H ₂ gas to react with the residual fluorine component adhering to the inner wall of the chamber 104, and the residual fluorine component Reduce and remove.

  In this way, the cleaning of the CVD apparatus is completed. Thereafter, the wafer is loaded into the chamber 104 and placed on the electrostatic chuck 108, and a semiconductor thin film forming process such as an FSG film is performed.

In this reference example, since the ceramic cover 110 is disposed in close contact with the electrostatic chuck, the ceramic cover 110 is disposed without a gap from the surface of the electrostatic chuck 108. Therefore, the NF ₃ supplied to the chamber 104 is prevented from entering between the ceramic cover 110 and the surface of the electrostatic chuck 108, and the adsorption of the fluorine component to the surface of the electrostatic chuck 108 is prevented. In the process, F degassing from the electrostatic chuck 108 on which the wafer (substrate) is arranged can be prevented.

(First embodiment)
In the present embodiment, as a method for cleaning the semiconductor manufacturing apparatus shown in FIG. 1, the surface of the electrostatic chuck 108 is exposed when the apparatus is idle (when waiting for semiconductor thin film formation) before the substrate is carried into the chamber 104. While supplying, for example, 100 to 1000 sccm of H ₂ gas (Ar / H ₂ gas) diluted into Ar gas as an inert gas from the injector 106 into the chamber 104, the pressure in the chamber 104 is set to, for example, 0.1333 to 1 The pressure of about 333 Pa (1 to 10 mTorr) is maintained. Here, the inert gas is not limited to Ar gas, and He gas may be used.

Then, plasma with a frequency of 450 kHz, for example, is generated from the bell jar 102 as the upper electrode at an output of 1000 to 5000 W to excite H ₂ gas and react with residual fluorine components adsorbed on the inner wall of the chamber 104 and the exposed surface of the electrostatic chuck 108. The residual fluorine component is reduced and removed.

  Thereafter, the wafer is loaded into the chamber 104 and placed on the electrostatic chuck 108, and a semiconductor thin film forming process such as an FSG film is performed.

Conventionally, O ₂ gas (Ar / O) always diluted from the injector 106 to Ar gas in order to maintain the temperature in the chamber 104 when the apparatus is idle other than the semiconductor thin film, fluoride-based cleaning gas cleaning process, and fluorine reduction process. ₂ ), and plasma is generated from the bell jar 102. Recently, a mixed gas (H ₂ / O ₂₎ of H ₂ gas and O ₂ gas is used instead of Ar / O ₂ gas for the purpose of reducing the fluorine. Gas) is partly encouraged (see, for example, JP-A-9-249976). However, when H ₂ / O ₂ gas is used, H ₂ O is generated in the chamber 104 due to excitation by plasma, and there is a problem that residual H ₂ O is taken into the film during film formation.

Therefore, in the present embodiment, when the apparatus is idle, a mixed gas of Ar gas and H ₂ gas that can obtain plasma stability equivalent to O ₂ is supplied into the chamber 104 to generate plasma, thereby generating H _2. It is possible to reduce and remove the fluorine component adsorbed on the inner wall of the chamber 104 and the exposed surface of the electrostatic chuck 108 without generating O, and the electrostatic chuck for disposing the wafer (substrate) in the subsequent semiconductor thin film formation process. F degassing from 108 can be prevented.

(Second Embodiment)
In the present embodiment, after the first embodiment is performed, for example, 13.56 MHz from the electrostatic chuck 108 immediately before the substrate is loaded into the chamber 104 (for example, 30 to 60 seconds before). A plasma having a frequency is generated at an output of 100 to 200 W.

In the present embodiment, plasma is generated from the electrostatic chuck 108 immediately before the substrate is loaded into the chamber 104, so that H ⁺ and Ar ⁺ supplied and decomposed in the pretreatment collide with the electrostatic chuck 108. Then, F adsorbed on the surface of the electrostatic chuck 108 is separated by the energy, and the residual fluorine component can be removed more effectively. The electrostatic chuck 108 for disposing the wafer (substrate) in the subsequent semiconductor thin film forming process. F can be prevented from degassing.

  In the present embodiment, the plasma output generated from the electrostatic chuck 108 just before loading the substrate into the chamber 104 is weakened to about 100 to 200 W, so that the surface of the electrostatic chuck 108 is also damaged. There is no F.

In the first and second embodiments, the embodiment using the NF ₃ gas as the fluoride-based cleaning gas has been described. However, the present invention is not limited to this, and CF ₄ , C ₃ F ₈ , C ₂ F ₆ , and ClF ₃ are used. It can also be used. Also it has been described the form of using H ₂ gas as the fluorine reducing gas is not limited thereto, and NH ₃ gas may be used a gas containing hydrogen.

  In any of the above-described embodiments, it is needless to say that the present invention is not construed in a limited manner and can be realized within the range satisfying the requirements of the present invention.

It is a schematic block diagram which shows the semiconductor manufacturing apparatus concerning a reference example.

Explanation of symbols

100 apparatus main body 102 bell jar (reactor)
102 Luger 104 Chamber 106 Injector 107 Injector 108 Electrostatic chuck (substrate support electrode)
110 Ceramic cover (insulation cover)
112 Supply pipe

Claims (5)

A method for cleaning a semiconductor manufacturing apparatus, in which a substrate is disposed on a substrate support electrode provided in a reaction furnace, and a semiconductor thin film is formed on the substrate,
When waiting for semiconductor thin film formation before carrying the substrate into the reactor,
A cleaning method of a semiconductor manufacturing apparatus, comprising: a cleaning step of generating plasma after supplying hydrogen gas and inert gas into the reaction furnace.   The method for cleaning a semiconductor manufacturing apparatus according to claim 1, wherein the inert gas is at least one selected from Ar gas and He gas.   The method for cleaning a semiconductor manufacturing apparatus according to claim 1, further comprising a step of generating plasma from the substrate support electrode immediately before the substrate is carried into the reaction furnace.   4. The method of cleaning a semiconductor manufacturing apparatus according to claim 3, wherein an output of plasma generated from the substrate support electrode is 100 to 200 W.   After performing cleaning by the semiconductor manufacturing apparatus cleaning method according to any one of claims 1 to 4, a substrate is disposed on a substrate support electrode provided in the reaction furnace, and a source gas is supplied into the reaction furnace. And a step of generating plasma and forming a semiconductor thin film on the substrate.

Images