JP2008121054A - Method for cleaning vacuum treatment apparatus, and vacuum treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning a vacuum treatment apparatus, which can inhibit halogens from remaining in a chamber when cleaning the chamber while using a gas containing halogens as a cleaning gas, and to provide a vacuum treatment apparatus. <P>SOLUTION: This cleaning method comprises the steps of: removing a deposit having deposited on the inside of the chamber 10 (step 205 to step 208), by introducing the gas containing halogens into the chamber 10; introducing a reductive gas into the chamber 10 (step 209); and generating plasma of the reductive gas (step 210). The treatment can inhibit the halogens from remaining in the chamber 10, and can reduce the occurrence of metallic contamination originating in the halogens. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cleaning method for a substrate processing apparatus and a vacuum processing apparatus, and more particularly to a cleaning method for a vacuum processing apparatus using a cleaning gas containing halogen or a halogen compound and a vacuum processing apparatus for performing the cleaning method.

  In the manufacturing process of a semiconductor device, a vacuum treatment is performed on a semiconductor substrate to form a material film made of an insulator, a conductor, or the like by a CVD (Chemical Vapor Deposition) method or a PVD (Physical Vapor Deposition) method. The device is in use. As an example of such a vacuum processing apparatus, FIG. 5 shows a configuration of a vacuum processing apparatus that performs plasma deposition using plasma.

  As shown in FIG. 5, this type of vacuum processing apparatus 100 includes, for example, a substantially cylindrical chamber 10 having a vertical axis. Inside the chamber 10 is provided a stage 20 on which the substrate to be processed 90 is placed substantially horizontally. The upper wall 11 of the chamber 10 is provided with a shower plate 30 having a number of gas introduction holes 31 in a plane parallel to the substrate mounting surface of the stage 20.

  Further, a gas supply pipe 51 communicates with the upper wall 11. The other end of the gas supply pipe 51 is provided with a gas supply unit 50 for supplying a raw material gas for forming a material film and a process gas such as a cleaning gas for performing a chamber cleaning process described later. The gas supply unit 50 includes a source gas supply unit 53 that supplies a source gas, a cleaning gas supply unit 54 that supplies a cleaning gas, and an inert gas supply unit 55 that supplies an inert gas. A mass flow controller 52 is interposed between 54 and 55 and the gas supply pipe 51. Then, the supply amount control unit 57 instructs each mass flow controller 52 of the flow rate of the gas supplied by each of the supply units 53, 54, 55, so that the gas supply unit 50 (53, 54, 55), the process gas is introduced into the gas supply pipe 51. The process gas introduced into the gas supply pipe 51 in this way is uniformly ejected from the gas introduction hole 31 toward the stage 20.

  A gas exhaust pipe 61 communicates with the lower wall 12 of the chamber 10. The gas exhaust pipe 61 includes a throttle valve 62 and the other end is connected to a vacuum pump 63. Then, by setting the opening amount (rotation angle) of the throttle valve 62 to a predetermined amount, the exhaust amount by the vacuum pump 63 is controlled, and the internal pressure of the chamber 10 is maintained at a predetermined pressure.

  On the other hand, the stage 20 is supported at the tip of a shaft 21 that can be inserted into and removed from the lower wall 12 of the chamber 10, and is configured to be movable up and down in the chamber 10. For example, the stage 20 is close to the loading / unloading position at which the substrate 90 is loaded / unloaded via the substrate loading / unloading port 14 provided in the lower part of the side wall 13 of the chamber 10 so as to be freely opened and closed. It is configured to be movable to a processing position where film formation or the like is performed, a cleaning position closer to the shower plate 30 than the processing position, and the like.

  The stage 20 is provided with heat generating means for setting the stage temperature (the temperature of the substrate to be processed) to a predetermined temperature. In the example of FIG. 5, the resistance heater 22 is embedded in the stage 20 as a heating means, and the stage temperature is maintained at a predetermined temperature by controlling the amount of current that the DC power supply 71 supplies to the resistance heater 22. .

  In the example of FIG. 5, a high frequency power source 72 and a high frequency power source 73 are connected to the shower plate 30 and the stage 20, respectively. Then, when one or both of the high-frequency power source 72 and the high-frequency power source 73 apply high-frequency power, process gas plasma is generated between the shower plate 30 and the stage 20.

  In the film forming process in the vacuum processing apparatus 100 having the above-described configuration, the source gas introduced into the chamber 10 from the source gas supply unit 53 is turned into plasma, and the target substrate 90 placed on the stage 20 is subjected to the plasma. As a result, the material film corresponding to the source gas is deposited on the substrate 90 to be processed. At this time, the material film is deposited not only on the substrate to be processed 90 but also on the inner wall of the chamber 10 and members disposed in the chamber 10. Unnecessary material films (hereinafter referred to as deposits) deposited on the inner wall of the chamber 10 and members in the chamber 10 cause deterioration of the film thickness uniformity of the material film and generation of particles (fine particles). Usually, a cleaning process for removing the deposits (hereinafter referred to as chamber cleaning) is periodically performed.

For example, in a semiconductor device, the formation of a metal film such as a titanium film or a titanium nitride film, which is frequently used for improving the adhesion between the conductor film and the insulating film and reducing the contact resistance between the conductor film and the conductor film. In the vacuum processing apparatus performing the above, the chamber cleaning contains halogen and halogen compounds (hereinafter referred to as halogens) such as Cl ₂ , F ₂ , ClF ₃ , C ₂ F _6, etc., which have high reactivity with the metal film. This is implemented by introducing a cleaning gas into the chamber 10 (see, for example, Patent Document 1).

  FIG. 6 is a flowchart showing a series of processes performed in the vacuum processing apparatus 100 in the course of the above-described titanium film formation and chamber cleaning. FIG. 7 shows an example of processing conditions for each process in the chamber cleaning. In FIG. 6, the process from step 601 to step 603 is a film forming process, and the process from step 605 to step 608 is chamber cleaning. In the following description, it is assumed that no deposit is present in the chamber 10 at the start of the film forming process on the first substrate 90 to be processed.

As shown in FIG. 6, first, in the film forming process, the stage 20 is moved to the loading / unloading position, and the substrate 90 to be processed is placed on the stage 20 (step 601). Next, after the stage 20 is moved to a processing position close to the shower plate 30 (for example, the distance from the shower plate 30 is 9 mm), the raw material gas for the titanium film is predetermined from the raw material gas supply unit 53 of the gas supply unit 50. And the source gas is turned into plasma (step 602). At this time, the internal pressure of the chamber 10 is maintained at, for example, 5 Torr by controlling the opening amount of the throttle valve 62. The state is maintained for a time corresponding to the target film thickness of the titanium film. In general, a gas containing TiCl ₄ is often used as the source gas.

  Thereafter, the generation of plasma is stopped, the stage 20 is moved to the loading / unloading position, and the substrate to be processed 90 is unloaded (step 603).

  When the film forming process is completed as described above, it is determined whether or not to perform chamber cleaning. The determination may be made based on, for example, the number of film forming processes and the accumulated processing time.

  When the chamber cleaning is started, first, as shown in FIGS. 6 and 7, the throttle valve 62 is fully opened (TFO: Throttle valve Full Open), that is, the internal pressure of the chamber 10 is not controlled. Then, evacuation is performed for several seconds, and the gas in the chamber 10 is exhausted (step 604 Yes → step 605).

  Subsequently, after the stage 20 is moved to a cleaning position (for example, a position with a distance of 7.5 mm from the shower plate 30), chlorine gas as a cleaning gas is transferred from the cleaning gas supply unit 54 into the chamber 10 in the TFO state. Are introduced at a predetermined flow rate for several seconds to several tens of seconds. In the example of FIG. 7, the flow rate of chlorine gas is 400 sccm.

  At this time, in the chamber 10, the deposit generated during the film formation process reacts with the introduced chlorine gas to generate a metal halide (metal chloride). Since the metal halide has a high vapor pressure, it is volatilized as soon as it is generated, and is discharged out of the chamber 10 together with unreacted chlorine gas (step 606). FIG. 7 illustrates an example in which chamber cleaning is performed without generating plasma. In chamber cleaning, the internal pressure of the chamber 10 is controlled as disclosed in Patent Document 1 described later. It may be performed by plasma of chlorine gas generated in a hot state.

  Thereafter, the stage 20 is lowered to a carry-in / out position or a position in the vicinity of the carry-in / out position, and argon gas, which is a purge gas, flows from the inert gas supply unit 55 into the chamber 10 at a predetermined flow rate for several seconds. Introduced and purged with chlorine gas in the chamber 10 (step 607). In the example of FIG. 7, the flow rate of argon gas is 7000 sccm, and the throttle valve 62 is in the TFO state.

  Subsequently, the supply of the purge gas from the inert gas supply unit 55 is stopped, and exhaust is performed in the TFO state in order to remove the purge gas in the chamber 10 (step 608).

  When chamber cleaning is completed as described above, when there is a substrate 90 to be processed subsequently, the above-described film forming process is performed (step 609 Yes → step 601 to step 603), and then processing is to be performed. When the substrate to be processed 90 does not exist, the process ends (No at step 609).

When the above-described chamber cleaning is performed every time a plurality of substrates 90 are formed, the processes from step 601 to step 603 in FIG. 6 are repeated as many times as the number of the substrates. (Step 604 No → Step 601). The chamber cleaning is generally performed in a state where the stage 20 is heated by the resistance heater 22. In the example of FIG. 7, the temperature of the resistance heater 22 is maintained at 650 ° C.
Special table 2002-529912 gazette

  However, in the chamber cleaning using the halogen-containing gas as the cleaning gas as described above, the halogens contained in the cleaning gas are completely removed from the chamber 10 due to adhesion to the chamber 10 and the members in the chamber 10. May remain without being discharged. In particular, since the shower plate 30 is a cleaning gas introduction path, halogens tend to remain.

  The members in the chamber 10 including the shower plate 30 and the inner wall of the chamber 10 are usually made of a metal such as nickel, iron, chromium, aluminum, or an alloy thereof, and the halogens remaining in the chamber 10 are Reacts with these members to form metal halides. The metal halide generated in this way is mixed into the material film formed on the substrate to be processed 90 in the film forming process after the chamber cleaning. Then, the metal halide mixed in the material film is ionized to generate metal ions, which cause migration of the metal ions and the like, thereby reducing the reliability of the semiconductor device.

  The present invention has been proposed in view of the above-described conventional circumstances, and in the chamber cleaning using a gas containing halogens as a cleaning gas, the halogens are prevented from remaining in the chamber and are reliable. An object of the present invention is to provide a vacuum processing apparatus cleaning method and a vacuum processing apparatus capable of stably forming a highly functional material film.

  In order to solve the above problems, the present invention employs the following means. That is, in the vacuum processing apparatus cleaning method according to the present invention, a gas containing halogen or a halogen compound is introduced into the chamber to remove unnecessary products accumulated in the chamber, and then reduced into the chamber. While introducing the gas containing the active substance, plasma of the gas is generated.

  As the reducing substance, at least one selected from hydrogen, monosilane, and disilane can be used.

  According to this configuration, halogens remaining in the chamber, in particular, the shower plate, which is a cleaning gas introduction path, can be efficiently discharged to the outside of the chamber, so that reliable deposition of a material film is stable. Can be performed.

  On the other hand, in another aspect, the present invention can provide a vacuum processing apparatus suitable for carrying out the above-described cleaning method. That is, the vacuum processing apparatus according to the present invention includes a stage on which a substrate to be processed is placed. At a position facing the stage, there are provided a plurality of gas introduction holes and an electrode for generating plasma from the process gas supplied from the gas introduction holes. Further, the vacuum processing apparatus includes a first gas supply means for supplying a cleaning process gas containing halogen or a halogen compound through the gas introduction hole, and a reducing substance through the gas introduction hole. Second gas supply means for supplying a process gas to be supplied. Then, after the processing using the process gas supplied by the first gas supply means is completed, the second gas supply means supplies the process gas, and the electrode generates plasma of the process gas.

  According to the present invention, it is possible to prevent halogens from remaining in the chamber. As a result, it is possible to reduce the mixing of the metal element into the material film formed in the film forming process after the chamber cleaning, and it is possible to stably form the highly reliable material film.

  Hereinafter, the present invention will be described in detail with reference to the drawings based on a case where the present invention is applied to a vacuum processing apparatus for forming a titanium film. FIG. 1 is a schematic configuration diagram of a vacuum processing apparatus to which the present invention is applied, and FIG. 2 is a flowchart showing a series of processes performed in film formation and chamber cleaning in the vacuum processing apparatus. FIG. 3 shows an example of processing conditions for each process in the chamber cleaning shown in FIG.

  As shown in FIG. 1, the vacuum processing apparatus 1 according to the present invention has a reducing property in which a gas supply unit 50 supplies a reducing gas containing a reducing substance such as hydrogen, silane, or disilane during chamber cleaning. A gas supply unit 56 is provided. Since the other structure is the same as that of the conventional vacuum processing apparatus 100, in the vacuum processing apparatus 1, parts having the same functions as those of the conventional vacuum processing apparatus 100 are denoted by the same reference numerals, and the following description is omitted. To do.

  Also in the vacuum processing apparatus 1 shown in FIG. 1, as shown in FIG. 2, the chamber cleaning (step 205 to step 213) is performed after the titanium film forming process (step 201 to step 203) is performed. Since the steps 201, 202, and 203 of the film forming process are the same as the steps 601, 602, and 603 of the conventional film forming process shown in FIG. 6, the description thereof is omitted here.

  When the titanium film formation process shown in step 201 to step 203 in FIG. 2 is completed, as in the conventional technique, for example, when the number of film formation processes reaches a predetermined number, or the accumulated processing time reaches a predetermined time. If reached, chamber cleaning is performed. In the present embodiment, it is assumed that the predetermined number is one and chamber cleaning is performed every time the film formation process of the substrate to be processed 90 is completed (step 204 Yes).

  In the chamber cleaning according to the present invention, first, as shown in FIG. 3, the chamber 10 is evacuated for several seconds with the throttle valve 62 set to TFO (step 205).

  Next, after the stage 20 is moved to the above-described cleaning position, a gas containing halogen as a cleaning gas in the TFO state enters the chamber 10 from the cleaning gas supply unit 54 for several seconds to several tens of seconds. be introduced. By introducing the halogen-containing gas, the deposits in the chamber 10 generated during the film formation process react with the halogens, and the deposits in the chamber 10 are removed (step 206). As shown in FIG. 3, in this embodiment, chlorine gas suitable for removing the titanium film is used as the cleaning gas, but it is not particularly limited. As the cleaning gas, any halogen-containing gas can be adopted as long as the deposit (here, titanium film) in the chamber 10 can be removed. Further, since the flow rate of the cleaning gas is set based on the volume of the chamber 10 and the like, it cannot be generally stated, but in the case of FIG. 3, the flow rate of chlorine gas is 400 sccm.

  When the removal of the deposits in the chamber 10 is completed, the stage 20 is lowered to the loading / unloading position or the vicinity thereof, and in the TFO state, the inert gas as the purge gas is supplied from the inert gas supply unit 55 to the chamber 10. Is introduced for several seconds (step 207). Thereby, the cleaning gas in the chamber 10 is replaced with the purge gas. In the example of FIG. 3, argon gas is employed as the purge gas, but other rare gases, nitrogen gas, and the like can also be used. In the example of FIG. 3, the flow rate of the purge gas is set to 7000 sccm, but the flow rate may be any flow rate that can purge the inside of the chamber 10 when the throttle valve 62 is in the TFO state.

  Subsequently, the supply of the purge gas from the inert gas supply unit 55 is stopped, the exhaust is performed in the TFO state, and the purge gas in the chamber 10 is exhausted (step 208).

  In the present invention, when the discharge of the purge gas is completed, the stage 20 is moved again to the cleaning position, and a reducing gas containing a reducing substance is introduced into the chamber 10 from the reducing gas supply unit 56. (Step 209). At this time, the internal pressure of the chamber 10 is set to a pressure capable of generating plasma, which will be described later. In the present embodiment, as shown in FIG. 3, the internal pressure of the chamber 10 is set to 5 Torr, hydrogen gas is supplied from the reducing gas supply unit 56 at a flow rate of 3000 sccm, and at the same time from the inert gas supply unit 55 as a dilution gas. Argon gas is supplied at a flow rate of 5000 sccm. The step 209 is continued for several seconds to several tens of seconds until the internal pressure of the chamber 10 and the flow rate of the process gas are stabilized.

  When the internal pressure of the chamber 10 and the flow rate of the process gas are stabilized, the high frequency power source 72 applies a high frequency power of about 600 W to the shower plate 30 (step 210). By applying the high frequency power, a plasma of a gas containing a reducing substance is generated immediately below the shower plate 30. At this time, an ion sheath is formed in the vicinity of the surface of the shower plate 30 that is an electrode for generating plasma due to the difference in mobility between electrons and ions generated in the plasma.

  In the state where the ion sheath is formed, the shower plate 30 is negatively charged. Therefore, ions having reducibility in the plasma (here, hydrogen ions) positively collide with the shower plate 30. For this reason, the halogens adhering and remaining on the shower plate 30 and the reducing substance can be reacted very efficiently, and can be removed from the shower plate 30. Further, when a solid is present in the plasma, an ion sheath is formed on the surface of the solid. For this reason, the halogens remaining on the other members in the chamber 10 are also removed in the same manner as the halogens remaining on the shower plate 30.

  As a result, it is suppressed that the halogens remaining in the chamber 10 react with the metal member in the chamber 10 to generate a metal halide, and a material film to be formed in a subsequent film forming process. The metal element mixed in can be reduced. The processing time of the reducing gas using plasma may be about 10 seconds.

  Thereafter, the high frequency power applied by the high frequency power source 72 is reduced and plasma purge is performed, then the generation of plasma is stopped, and the gas in the chamber 10 is exhausted by exhausting in the TFO state (step 211 → step 212). ). Then, when there is a substrate 90 to be processed subsequently, the above-described film forming process is performed (Step 213 Yes → Step 201 to Step 203), and when there is no substrate 90 to be processed subsequently. The process ends (No at step 213). The chamber cleaning described above is performed in a state in which the stage 20 is heated by the resistance heater 22 as in the prior art. In the example of FIG. 3, the temperature of the resistance heater 22 is maintained at 650 ° C.

  FIG. 4 shows a titanium film formed after the chamber cleaning (processing conditions shown in FIG. 3) by the cleaning method of the present invention and a film forming after the chamber cleaning (processing conditions shown in FIG. 7) by the conventional cleaning method. The result of having quantified the contaminating element which exists in the film | membrane surface using a fluorescent X-ray-analysis apparatus in each with the made titanium film | membrane is shown. In FIG. 4, the left vertical axis corresponds to the number of Ni and Cl atoms, and the right vertical axis corresponds to the number of Fe atoms. Further, the quantification is performed on the titanium film formed after each chamber cleaning in each of the two vacuum processing apparatuses, and the quantification results for each apparatus are shown separately in an upper stage and a lower stage. Note that the material of the shower plate of the vacuum processing apparatus used for film formation is Ni.

As can be understood from FIG. 4, in the case of the conventional cleaning method, a large amount of Ni exceeding 500 × 10 ¹⁰ atoms / cm ² is mixed in the titanium film formed in any apparatus. On the other hand, in the cleaning method of the present invention, the amount of Ni mixed is less than 0.01 × 10 ¹⁰ atoms / cm ² in any of the titanium films formed by any apparatus, which is greatly reduced. . Further, according to the cleaning method of the present invention, the amount of Cl mixed in the titanium film is greatly reduced as compared with the conventional cleaning method. In addition, Fe constituting other members in the chamber 10 has a mixing amount of about 0.1 × 10 ¹⁰ atoms / cm ² in the conventional cleaning method, but according to the cleaning method of the present invention, Fe The amount of contamination is further reduced.

  That is, according to the cleaning method of the present invention, it is possible to efficiently discharge the halogens remaining in the chamber 10, and as a result, it can be confirmed that unnecessary elements can be prevented from being mixed into the film formed after the cleaning. .

  As described above, according to the present invention, it is possible to prevent the halogens from remaining in the chamber during the chamber cleaning using the halogen-containing gas as a cleaning gas. As a result, the halogens remaining in the chamber react with the metal member in the chamber to suppress the formation of metal halides. In the subsequent film formation process, the metal element in the material film is prevented from being generated. Mixing can be reduced. Therefore, it is possible to stably form a highly reliable material film.

  The present invention is not limited to the embodiment described above, and various modifications and applications are possible within the scope of the effects of the present invention. For example, in the above description, the case where the material film is a titanium film has been described, but the above material film may be another metal film, a conductor film, or an insulating film. In the above description, the example of removing the deposits generated in the chamber at the time of forming the material film has been described. However, the present invention can naturally be applied to the case of removing deposits generated in the chamber at the time of etching. is there. That is, the present invention can be applied to any case where chamber cleaning is performed with a gas containing halogens in a vacuum processing apparatus.

  The present invention has an effect that halogens can be prevented from remaining in the chamber, and can be applied to a vacuum processing apparatus that introduces a halogen or a halogen compound to perform a chamber cleaning process.

The schematic block diagram of the vacuum processing apparatus to which this invention is applied. The flowchart which shows the process performed in the vacuum processing apparatus to which this invention is applied. The figure which shows an example of the process conditions of the cleaning method of this invention. The figure which shows the amount of mixing elements in the material film formed into a film by the vacuum processing apparatus to which this invention is applied. The schematic block diagram of the conventional vacuum processing apparatus. The flowchart which shows the process performed in the conventional vacuum processing apparatus. The figure which shows an example of the process conditions of the conventional cleaning method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Vacuum processing apparatus 10 Chamber 20 Stage 30 Shower plate 31 Gas introduction hole 50 Gas supply part 51 Gas supply pipe 53 Raw material gas supply part 54 Cleaning gas supply part (1st gas supply means)
55 Inert gas supply unit 56 Reducing gas supply unit (second gas supply means)
61 Gas exhaust pipe 71 DC power source 72, 73 High frequency power source

Claims (4)

In a cleaning method of a vacuum processing apparatus for performing plasma processing on a substrate to be processed accommodated in a chamber,
Introducing a gas containing halogen or a halogen compound into the chamber to remove unnecessary products deposited in the chamber;
Introducing a gas containing a reducing substance into the chamber and generating a plasma of the gas;
A method for cleaning a vacuum processing apparatus, comprising:   The method for cleaning a vacuum processing apparatus according to claim 1, wherein the reducing substance is at least one selected from hydrogen, monosilane, and disilane.   The vacuum processing apparatus cleaning method according to claim 1, wherein the vacuum processing apparatus includes a member containing metal in the chamber. In a vacuum processing apparatus that performs plasma processing on a substrate to be processed contained in a chamber,
A stage on which a substrate to be processed is placed;
An electrode that is provided at a position facing the stage, includes a plurality of gas introduction holes for supplying a process gas into the chamber, and generates plasma from the process gas;
First gas supply means for supplying a cleaning process gas containing halogen or a halogen compound through the gas introduction hole;
A second gas supply means for supplying a process gas containing a reducing substance via the gas introduction hole;
With
After the processing using the cleaning process gas supplied by the first gas supply unit is completed, the second gas supply unit supplies a process gas and generates plasma of the process gas by the electrode. A vacuum processing apparatus.

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