JP2007142018A - Cleaning method of film depositing device, and manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning method of a film depositing device capable of efficiently confirming whether the cleaning of a reaction vessel has been effected sufficiently or not. <P>SOLUTION: The cleaning method of film depositing device comprises a process for effecting CVD (chemical vapor deposition) treatment in the reaction vessel possessed by the film depositing device, a process (S2) for effecting first cleaning treatment employing plasma in the reaction vessel, a second cleaning process (S3) employing plasma stronger than the first cleaning treatment in the cleaning force, and a process (S4) for judging the degree of cleaning by the first cleaning process through the analysis of exhaust gas from the reaction vessel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a film forming apparatus cleaning method and a semiconductor device manufacturing method. In particular, the present invention relates to a film forming apparatus cleaning method and a semiconductor device manufacturing method capable of efficiently confirming whether or not a reaction container has been sufficiently cleaned.

The manufacturing process of a semiconductor device includes many steps of forming a silicon oxide film or a silicon nitride film on a silicon wafer by a CVD method. Since the CVD method is a method of forming a film by reacting a material gas inside a chamber (reaction vessel), a film is formed not only on a silicon wafer but also inside the chamber (for example, the inner wall of the chamber). Since this film becomes a source of particles, it must be removed. As a method for removing the film inside the chamber, there is a method in which plasma is generated in the chamber, the film adhering to the inside of the chamber is chemically etched to be changed into a gaseous substance, and exhausted to the outside of the chamber. For example, when the attached film is a silicon oxide film or a silicon nitride film, C ₃ F ₆ or the like is activated by applying a high frequency to C ₃ F ₆ or the like, and the silicon oxide film or the silicon nitride film is chemically etched to form SiF ₄

As a method for evaluating the degree of chamber cleaning by chemical etching, there is a method in which exhaust gas from the chamber is analyzed by a quadrupole mass analyzer or FT-IR, and the concentration of the product by chemical etching is measured. According to this method, when the concentration of the product is equal to or lower than the threshold value, it can be determined during cleaning that the cleaning to be evaluated has been sufficiently performed (see, for example, Patent Document 1).
JP-A-6-224163 (17th to 19th paragraphs)

  Since the above method determines whether or not the cleaning has been sufficiently performed based on the analysis result during the cleaning, it is effective when it is performed under the condition that the inside of the chamber is chemically etched in advance. It is. Therefore, it is sufficiently effective as an apparatus maintenance in the mass production stage where conditions are determined in advance. However, in cleaning in basic experiments where conditions are not determined, for example, the plasma distribution during chemical etching may be biased and a film may remain locally. Even if it becomes, cleaning may be insufficient. Therefore, conventionally, in the condition setting or basic experiment stage, in order to confirm that the cleaning has been sufficiently performed, the treatment is repeated for a long time until the state where the film residue is visible, and then the chamber is opened to the atmosphere. And visually confirmed the inside. Therefore, a great deal of labor was required.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for cleaning a film forming apparatus capable of efficiently confirming whether or not the reaction container has been sufficiently cleaned. And a method of manufacturing a semiconductor device.

In order to solve the above problems, a method for cleaning a film forming apparatus according to the present invention includes a step of performing a CVD process in a reaction vessel included in the film forming apparatus,
Performing a first cleaning process using plasma on the reaction vessel;
The first cleaning process is performed on the reaction container by performing a second cleaning process using plasma having a cleaning power stronger than that of the first cleaning process, and analyzing a component of exhaust gas from the reaction container. And determining the degree of cleaning.

  According to the cleaning method of the film forming apparatus, the degree of cleaning by the first cleaning process is determined by analyzing the exhaust gas component during the second cleaning process without opening the reaction container to the atmosphere. to decide. Therefore, it is possible to efficiently determine the degree of cleaning by the first cleaning process.

  In the step of determining the degree of cleaning, for example, when the concentration of a specific component contained in the exhaust gas is a predetermined value or less, it is determined that the first cleaning process is appropriate. The CVD process is, for example, a process for forming a silicon oxide film or a silicon nitride film on a substrate, or a process for forming a tungsten film on a substrate. The present invention employs plasma cleaning using a fluorine-based etching gas. Applicable to all membrane devices.

  The first cleaning process and the second cleaning process may use different cleaning gases. Further, when the cleaning gases used in the first and second cleaning processes are the same, the flow rate of the cleaning gas in the second cleaning process is the same as the cleaning gas in the first cleaning process. The flow rate of the gas may be larger. When the type of cleaning gas used and the pressure in the reaction container are the same in the first cleaning process and the second cleaning process, respectively, the plasma input in the second cleaning process is: It may be higher than the plasma input in the first cleaning process. When the cleaning gases used in the first and second cleaning processes are the same, the pressure in the reaction container in the second cleaning process is the pressure in the reaction container in the first cleaning process. It may be higher than the pressure.

  In the second cleaning process, the pressure in the reaction vessel may be changed. In this case, since the plasma distribution changes during the second cleaning process, it becomes easy to detect a film partially remaining after the first cleaning process.

Another method for manufacturing a semiconductor device according to the present invention includes a step of performing a first cleaning process using plasma on a reaction vessel,
The first cleaning process is performed on the reaction container by performing a second cleaning process using plasma having a cleaning power stronger than that of the first cleaning process, and analyzing a component of exhaust gas from the reaction container. Determining the degree of cleaning by
Carrying a semiconductor substrate into the reaction vessel;
Performing a CVD process on a semiconductor substrate located in the reaction vessel;
And unloading the semiconductor substrate from the reaction vessel.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram for explaining a configuration of a film forming apparatus used in a method for manufacturing a semiconductor device according to the present invention. This film forming apparatus is an apparatus for forming a silicon oxide film (for example, an interlayer insulating film) on a silicon wafer by a CVD method. He gas containing TEOS (Tetraethyl orthosilicate Tetraethoxysilane) and ozone gas are used as source gases. These source gases are supplied into the chamber (reaction vessel) 10 through the pipes 35 and 36, the mixing valve 34, and the pipe 37.

  Inside the chamber 10, a shower head 11 and a susceptor 12 are disposed so as to face each other. The shower head 11 is connected to a high frequency power source 23 via a capacitor 21 and a matching unit 22, and the susceptor 12 is grounded. The source gas sent from the pipe 37 is supplied from the shower head 11 to a space between the shower head 11 and the susceptor 12 and is converted into plasma by applying a high frequency in this space.

A pipe 30 is further connected to the mixing valve 34. The pipe 30 is a pipe through which a gas for cleaning the inside of the chamber 10 flows. A pipe 31 for supplying C ₃ F ₆ , a pipe 32 for supplying NF ₃ , and a pipe 33 for supplying O ₂ are provided upstream. It is connected. Mass piping controllers (MFC) 31a, 32a, and 33a are attached to the pipes 31, 32, and 33, respectively.

  An exhaust pipe 40 is attached to the chamber 10. A throttle valve 41 is attached to the exhaust pipe 40. A dry pump 42 that exhausts the chamber 10 and depressurizes it is attached downstream of the exhaust pipe 40. A pipe 46 for sending the exhausted gas to an exhaust gas processing system (not shown) is attached downstream of the dry pump 42.

  An FT-IR 44 is attached to the pipe 46 in order to analyze the components of the exhaust gas flowing through the pipe 46. The exhaust gas flowing through the pipe 46 is sent to the FT-IR 44 via the pipe 43. The exhaust gas analyzed by FT-IR is returned to the pipe 46 via the pipe 45. A diaphragm pump 45 a is attached to the pipe 45. By operating the diaphragm pump 45a, a part of the exhaust gas flowing through the pipe 46 flows in the order of the pipe 43, the FT-IR 44, and the pipe 45.

  FIG. 2 is a flowchart for explaining a first operation example of the film forming apparatus shown in FIG. The operation shown in this flowchart is for determining the cleaning conditions of the film forming apparatus. First, He gas and ozone gas containing TEOS are introduced into the chamber 10, and a high frequency is applied to them to generate plasma, thereby executing silicon oxide film formation processing (S1). As a result, a silicon oxide film adheres inside the chamber 10.

Next, a first cleaning process is performed (S2). This cleaning process is for removing the silicon oxide film adhering to the inside of the chamber 10 by etching. As the cleaning gas, a mixed gas of C ₃ F ₆ and O ₂ is used. C ₃ F ₆ and O ₂ are introduced into the chamber 10 through the shower head 11 and then turned into plasma when a high frequency is applied to chemically etch the silicon oxide film adhering to the inside of the chamber 10. The silicon oxide film changes to SiF ₄ that is a gas by chemical etching, and is exhausted to the outside of the chamber 10 by the dry pump 42.

In the first cleaning process, the FT-IR 44 analyzes the exhaust gas from the chamber 10 and measures the concentration of SiF ₄ contained in the exhaust gas. When the concentration of SiF ₄ becomes equal to or lower than the first reference value, it can be determined that the inside of the chamber 10 has been sufficiently cleaned, and thus the first cleaning process is terminated. Note that even after the first cleaning process, the silicon oxide film may partially remain, for example, when the plasma distribution during the first cleaning process is uneven.

Next, a second cleaning process is performed (S3). This cleaning process is a process for confirming whether or not the silicon oxide film adhering to the inside of the chamber 10 has been sufficiently removed by the first cleaning process, and has a condition that the chemical etching power is stronger than that of the first cleaning process. Done in Specifically, by using a mixed gas of NF ₃ and O ₂ as the cleaning gas, the chemical etching force becomes stronger than that in the first cleaning process. When the silicon oxide film partially remains after the first cleaning process, the remaining silicon oxide film is chemically etched by the second etching process and changed to SiF ₄ , and the chamber is controlled by the dry pump 42. 10 is exhausted to the outside.

In the second cleaning process, the FT-IR 44 analyzes the component of the exhaust gas from the chamber 10 and measures the concentration of SiF ₄ contained in the exhaust gas. If the maximum value of the SiF ₄ concentration is less than or equal to the second reference value (S4: Yes), it is determined that the cleaning condition in the first cleaning process is appropriate, and this cleaning condition is set as the actual cleaning condition. .

If the SiF ₄ concentration is equal to or higher than the second reference value (S4: No), it is determined that there is a residual silicon oxide film after the first cleaning process, and the cleaning conditions in the first cleaning process are inappropriate. . Then, the cleaning condition in the first cleaning process is changed (S5), and the process returns to the above-described process of S2.

  In the second cleaning process, the pressure inside the chamber 10 may be changed in the middle. For example, lower pressure in the second half than in the first half. In this case, since the plasma distribution in the second cleaning process changes in the middle, the detection accuracy of the remaining film of the silicon oxide film is improved.

  As another method for making the chemical etching power of the second cleaning process stronger than that of the first cleaning process, the cleaning gases used in the first and second cleaning processes are the same. In some cases, there are a method in which the flow rate of the cleaning gas is made higher than that in the first cleaning process, and a method in which the pressure in the chamber 10 is made higher than that in the first cleaning process. Further, when the type of cleaning gas used and the pressure in the chamber 10 are the same as those in the first cleaning process, there is a method of increasing the high frequency input for converting the cleaning gas into plasma.

FIG. 3A is a graph showing an example of the detection result of SiF ₄ of FT-IR 44 in the first operation example. The horizontal axis represents time, and the vertical axis represents the concentration of SiF ₄ . In the second cleaning process in this graph, the pressure inside the chamber 10 is set to a low pressure in the middle. In this graph, SiF ₄ is detected in the second cleaning process.

FIG. 3B is a bar graph showing the maximum value of the SiF ₄ concentration during the second cleaning process in the example shown in FIG. This graph shows each case where the first cleaning process is performed under the first condition and the second condition. As shown in this figure, the maximum value of the SiF ₄ concentration during the second cleaning process varies greatly depending on the conditions of the first cleaning process. From this, it is possible to determine whether or not the silicon oxide film remains after the first cleaning process by the second cleaning process.

Thus, according to the first operation example, it is determined whether the chamber 10 has been sufficiently cleaned based on the maximum value of the SiF ₄ concentration during the second cleaning process. For this reason, it is possible to efficiently confirm whether or not the cleaning has been sufficiently performed without opening the chamber 10 to the atmosphere. Therefore, it can be efficiently determined whether or not the conditions of the first cleaning process are appropriate.

  FIG. 4 is a flowchart for explaining a second operation example of the film forming apparatus shown in FIG. The operation shown in this flowchart shows a case where the film forming apparatus shown in FIG. 1 is used in an interlayer insulating film forming process of a semiconductor device.

First, a silicon wafer is carried into the chamber 10 (S21). On this silicon wafer, semiconductor elements such as transistors are formed in advance. Subsequently, an He gas and an ozone gas containing TEOS are introduced into the chamber 10, and a plasma is generated by applying a high frequency to the gas, thereby forming an interlayer insulating film made of a silicon oxide film on the silicon wafer (S22). ).
Thereafter, the silicon wafer is unloaded from the chamber 10 (S23).

  If the number of times the above-described interlayer insulating film forming process has been performed is equal to or less than a predetermined number, it is determined that it is not the cleaning timing (S24: No), and the process returns to S21. When the number of times the above-described interlayer insulating film forming process has been performed is a predetermined number, it is determined that it is the cleaning timing (S24: Yes), and the first cleaning process (S2) shown in the first operation example is performed. ) And the second cleaning process (S3). The conditions for the first cleaning process are determined according to the first operation example.

Next, it is determined whether the concentration of SiF ₄ during the second cleaning process is equal to or lower than the second reference value (S4). When the maximum value of the SiF ₄ concentration is equal to or less than the second reference value (S4: Yes), it is determined that the inside of the chamber 10 has been sufficiently cleaned by the first cleaning process, and the process returns to S21.

If the SiF ₄ concentration is equal to or higher than the second reference value (S4: No), it is determined that there is a residual silicon oxide film after the first cleaning process, and the cleaning conditions in the first cleaning process are changed. (S5) The first cleaning process is performed again.

  As described above, according to the second operation example, it is possible to efficiently confirm whether or not the chamber 10 has been sufficiently cleaned without opening the chamber 10 to the atmosphere.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the gas used in the first cleaning process is C ₃ F ₆ , but when the gas used in the second cleaning process is NF ₃ , C ₃ F ₈ , COF ₂ , or it may be a C ₂ F _6. Further, although the gas used in the second cleaning process is NF ₃ , COF ₂ or C ₂ F ₆ may be used when the gas used in the first cleaning process is C ₃ F ₆ .

In the above-described embodiment, the film forming apparatus forms the silicon oxide film, but a silicon nitride film or a tungsten film may be formed. In the case of forming a silicon nitride film, as source gases, SiH ₄ —NH ₃ , SiH ₄ —N ₂ , SiCl ₄ —NH ₃ —H ₂ , SiH ₄ —NH ₃ —H ₂ , SiH ₂ Cl ₂ —NH ₃ — N ₂ or SiCl ₄ —N ₂ H ₄ —H ₂ is used. In the case of forming a tungsten film, tungsten fluoride (WF ₆ ) is used as a source gas. In any of these cases, the cleaning gas is the same as in the above-described embodiment.

Schematic for demonstrating the structure of the film-forming apparatus. 2 is a flowchart for explaining a first operation example of the film forming apparatus shown in FIG. 1. (A) is a graph showing an example of the detection result of the SiF ₄ in the FT-IR44, (B) is a bar graph showing the maximum value of the SiF ₄ concentration at the second cleaning process. 6 is a flowchart for explaining a second operation example of the film forming apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Chamber, 11 ... Shower head, 12 ... Susceptor, 21 ... Capacitor, 22 ... Matching device, 23 ... High frequency power supply, 31, 32, 33, 34, 35, 36, 37, 43, 45, 46 ... Piping, 31a 32a, 33a ... Mass flow controller, 34 ... Mixing valve, 40 ... Exhaust piping, 41 ... Throttle valve, 42 ... Dry pump, 45a ... Diaphragm pump

Claims (9)

A step of performing a CVD process in a reaction vessel of the film forming apparatus;
Performing a first cleaning process using plasma on the reaction vessel;
The first cleaning process is performed on the reaction container by performing a second cleaning process using plasma having a cleaning power stronger than that of the first cleaning process, and analyzing a component of exhaust gas from the reaction container. Determining the degree of cleaning by
A method for cleaning a film forming apparatus comprising:   2. The film formation according to claim 1, wherein in the step of determining the degree of cleaning, the first cleaning process is determined to be appropriate when the concentration of the specific component contained in the exhaust gas is a predetermined value or less. How to clean the device.   The film forming apparatus cleaning method according to claim 1, wherein the CVD process is a process of forming a silicon oxide film or a silicon nitride film on a substrate, or a process of forming a tungsten film on the substrate.   The film-forming apparatus cleaning method according to claim 1, wherein the first cleaning process and the second cleaning process use different cleaning gases.   The cleaning gases used in the first and second cleaning processes are the same, and the flow rate of the cleaning gas in the second cleaning process is the same as that for the cleaning in the first cleaning process. The cleaning method of the film-forming apparatus as described in any one of Claims 1-3 which is more than the flow volume of gas.   The type of cleaning gas used and the pressure in the reaction vessel are the same in the first cleaning process and the second cleaning process, respectively, and the plasma input in the second cleaning process is The method for cleaning a film forming apparatus according to any one of claims 1 to 3, wherein the plasma input is higher than the plasma input in the first cleaning process.   The cleaning gases used in the first and second cleaning processes are the same, and the pressure in the reaction container in the second cleaning process is the same as that in the reaction container in the first cleaning process. The cleaning method of the film-forming apparatus as described in any one of Claims 1-3 higher than a pressure.   The film-forming apparatus cleaning method according to claim 1, wherein the pressure in the reaction vessel is changed in the second cleaning process. Performing a first cleaning process using plasma on the reaction vessel;
The first cleaning process is performed on the reaction container by performing a second cleaning process using plasma having a cleaning power stronger than that of the first cleaning process, and analyzing a component of exhaust gas from the reaction container. Determining the degree of cleaning by
Carrying a semiconductor substrate into the reaction vessel;
Performing a CVD process on a semiconductor substrate located in the reaction vessel;
Unloading the semiconductor substrate from the reaction vessel;
A method for manufacturing a semiconductor device comprising:

Images