JP5110987B2 - Plasma processing method and computer-readable recording medium - Google Patents

Description

  The present invention relates to a plasma etching processing method, and more particularly to a plasma etching processing method that makes it possible to perform plasma processing stably over a long period of time.

In the plasma etching apparatus, a substrate to be processed is placed in a plasma processing chamber, a reactive gas is introduced into the plasma processing chamber, and a high-frequency power is further introduced into the plasma processing chamber. Furthermore, the substrate to be processed is etched by reacting it with the substrate to be processed placed on the substrate to be processed.
The substance removed from the substrate to be processed by the etching process is preferably discharged from the plasma processing chamber, but may remain in the plasma processing chamber. In some cases, the surface of the plasma processing chamber is scraped by the influence of plasma or the like and is deposited in the plasma processing chamber. These reaction products may affect the plasma processing characteristics of the substrate to be processed. For example, when the reaction product forms a solid film on the inner surface of the plasma processing chamber, and this film peels off and adheres to the substrate to be processed, this acts as a mask to hinder the etching process of the coated portion.
Another example of the influence of the plasma processing characteristics due to the reaction products remaining in the etching processing chamber is a change with time of the etching characteristics. The cause of the change in etching characteristics over time is not necessarily clear, but the following factors can be considered.

  For example, the reaction product forms a film on the inside of the processing chamber. As the ratio of the area covering the processing chamber surface of this film increases gradually, the active species that contribute to the etching reaction in the plasma adsorbed or desorbed on the processing chamber wall surface increase or decrease, for example, etching. There may be a gradual increase or decrease in speed. Further, outgassing may occur from the reaction product film, which may change the density of active species that contribute to the etching reaction in the processing chamber.

Other factors affecting the etching characteristics include the balance between the reaction product (deposited material) adhering to the surface to be processed of the substrate to be processed and the amount and energy of ion species in the plasma. If the reaction product coating ratio on the wall of the processing chamber changes, the balance between the reaction product (deposited material) and ions will be lost, and even if the etching shape is initially adjusted to a good etching shape, the processing shape will improve as the processing is repeated. May not be maintained.
Usually, in order to prevent the etching process characteristics from being deteriorated due to the reaction product remaining in the processing chamber, a process of cleaning the reaction product in the processing chamber using a cleaning gas is performed. In the cleaning process, it is desirable to use a gas system that has a function of gasifying reaction products that are easily deposited and discharging them to the outside of the plasma processing chamber. For example, a gas containing fluorine is often used as the cleaning gas. Fluorine is highly reactive and has the characteristic of reacting with many substances to gasify it, making it an indispensable element for cleaning treatment. In particular, a fluorine-containing gas is suitable for cleaning a reaction product containing silicon, which is often used as a substrate material for a semiconductor integrated circuit.

Typical examples of fluorine-containing gases used for cleaning are sulfur hexafluoride (SF ₆ ) and nitrogen trifluoride (NF ₃ ), but these gases are prone to global warming and can be replaced. Research and development of gas and exhaust gas treatment methods are underway. Carbonyl fluoride (COF ₂ ) or octafluoropropane (C ₃ F ₈ ) has been proposed as an alternative gas that is unlikely to cause global warming and can maintain the cleaning effect.

  As described above, a gas system containing fluorine is frequently used for the cleaning process, but there are cases where a solid that is difficult to vaporize is generated by fluorination. For example, aluminum tends to be fluorinated to produce aluminum fluoride, but aluminum fluoride is a chemically very stable substance that is difficult to vaporize, so care must be taken when deposits containing aluminum are present. is there. On the other hand, aluminum chloride is easily vaporized, and cleaning treatment using a gas system containing chlorine is often effective for deposits containing aluminum.

In addition, there is an increasing demand for etching various materials. For example, in order to improve the performance of semiconductor integrated circuit elements, materials such as gold and platinum that have low reactivity and are difficult to vaporize, or various ceramics that are difficult to etch have been proposed. Etching is required. When these so-called difficult-to-etch materials are etched, reaction products tend to remain in the processing chamber. For this reason, performing an appropriate cleaning process is an important issue.
Patent Document 1 is known as a plasma cleaning method using a conventional technique. This document shows that deposits remaining when an Al alloy / barrier metal laminated film is etched are cleaned by combining discharge with a gas containing chlorine and discharge with a gas containing fluorine.
JP-A-3-62520

  Patent Document 1 does not consider the case of etching a so-called difficult-to-etch material. Al alloy reacts chemically with chlorine and vaporizes as aluminum chloride and is easily etched. However, in the case of a substance containing aluminum atoms, for example, a chemically stable compound such as aluminum oxide, for example, chlorine Even when exposed to plasma, the etching reaction hardly proceeds.

  Therefore, for example, boron trichloride or silicon tetrachloride is used as a reducing gas to reduce aluminum oxide, and since a physical sputtering action by ions in plasma is used, a relatively large bias power is applied to the substrate to be processed. Etching is carried out by applying. When aluminum oxide is etched using a physical sputtering action, a reaction product containing a large amount of aluminum oxide is likely to be deposited in the processing chamber. That is, compared with the case of an Al alloy that is easily etched chemically, the physical sputtering action is used in combination, so that the ratio of reaction products such as aluminum oxide that are difficult to vaporize increases. As described above, aluminum oxide is chemically stable and does not react easily only by exposure to chlorine plasma, and cleaning of deposits in the processing chamber becomes more difficult.

  Furthermore, when cleaning with a fluorine-based gas is performed in a state where a reaction product containing aluminum remains, aluminum fluoride is easily generated. Aluminum fluoride is chemically very stable and tends to adversely affect the etching process as a solid deposit.

  The present invention has been made in view of these problems, and provides an effective plasma cleaning technique in the case of etching a material to be etched including a difficult-to-etch material.

  In order to solve the above problems, the present invention employs the following means.

A decompression chamber, a gas supply means for supplying a treatment gas to the decompression chamber, and a substrate electrode for mounting and holding a substrate to be treated containing a compound containing oxygen atoms and aluminum and silicon in the decompression chamber the Te decompression in the processing chamber is supplied to the processing gas by supplying a high-frequency energy with a plasma generation means for generating plasma by the generated plasma subjected to plasma etching process on the target substrate plasma processing method odor, A first plasma cleaning process for carrying out plasma cleaning of the reduced pressure processing chamber by supplying a gas containing silicon tetrachloride to the reduced pressure processing chamber after unloading the substrate to be processed after the plasma etching processing has been completed; After the first plasma cleaning process, a fluorine-containing gas is supplied to the decompression process chamber to fill the decompression process chamber. And a second plasma cleaning process of Zuma cleaning.

  Since the present invention has the above-described configuration, it is possible to provide an effective plasma cleaning technique when etching an etching target material including a difficult-to-etch material.

  Hereinafter, the best embodiment will be described with reference to FIGS. FIG. 1 is a diagram for explaining a plasma etching apparatus used in the present invention.

  The microwave generated by the microwave generator 101 is introduced into the rectangular-circular waveguide converter 104 via the automatic matching machine 102 and the rectangular waveguide 103. Further, it is introduced into the processing chamber 110 through the circular waveguide 105, the cavity 106, the electromagnetic wave introduction window 107, and the gas dispersion plate 108.

  The processing gas used for the etching is a processing chamber 110 through a gas supply device 109, a minute gap between the electromagnetic wave introduction window 107 and the gas dispersion plate 108, and a plurality of minute gas introduction holes provided in the gas dispersion plate 108. Supplied in.

  A substrate electrode 112 on which a substrate to be processed 111 is placed is provided in the processing chamber 110. A substrate bias power supply 114 is connected to the substrate electrode 112 via an automatic matching machine 113, and a bias potential can be applied to the substrate to be processed.

  A vacuum exhaust system (not shown) is connected to the processing chamber 110, and the inside of the processing chamber is decompressed to exhaust a predetermined flow rate of gas supplied by the gas supply device 109 and reaction product gas generated by the etching reaction. Can do. The vacuum exhaust system can control the inside of the processing chamber 110 to a pressure suitable for the etching process by adjusting the exhaust speed.

  Further, a static magnetic field generator 115 is installed around the processing chamber 110, and a static magnetic field can be applied to the processing chamber. The static magnetic field generator 115 can control the strength and distribution of the static magnetic field in the processing chamber 110, and can control the distribution of plasma generated in the processing chamber 110. Further, by applying a static magnetic field having a magnitude that causes an electron cyclotron resonance phenomenon to the frequency of the microwave to be input, microwave energy is efficiently supplied to the electrons, and plasma generation is facilitated. The processing gas is activated by the generated plasma, and the processing target substrate 111 is etched. With the bias potential applied to the substrate 111 to be processed, ions in the plasma can be attracted to the surface of the substrate 111 to improve the etching rate and characteristics such as the etching shape.

  In this embodiment, the substrate to be processed containing silicon and a compound containing oxygen atoms and aluminum atoms (or hafnium) is etched by an etching apparatus, and the substrate to be processed is removed from the processing chamber and then remains in the processing chamber. Reaction products are removed by plasma cleaning. This plasma cleaning is divided into a first cleaning step and a second cleaning step.

  In the first cleaning step, plasma cleaning is performed using a reducing gas system containing a halogen such as chlorine. For example, plasma cleaning is performed on a deposit containing aluminum oxide or aluminum fluoride by using a gas containing boron trichloride or silicon tetrachloride as a reducing gas containing halogen such as chlorine.

  Oxygen or fluorine is extracted from aluminum oxide or aluminum fluoride, and aluminum is vaporized as aluminum chloride and cleaned. For example, in the reaction between aluminum oxide and silicon tetrachloride, oxygen extracted from aluminum oxide is combined with silicon to generate silicon oxide. Silicon oxide does not evaporate and is deposited as a new reaction product. Similarly, for example, in the reaction of aluminum oxide and boron trichloride, boron oxide is deposited as a new reaction product.

  A second cleaning step is performed following the first cleaning step. The second cleaning step is plasma cleaning using a gas containing fluorine. By this second cleaning step, for example, a reaction product containing silicon is removed. Further, for example, newly generated deposits can be removed by extracting oxygen or fluorine in the first cleaning step. At this time, silicon oxide or boron oxide generated in the first cleaning step is vaporized and cleaned by plasma cleaning with a fluorine-based gas used in the second cleaning step.

  By performing the first cleaning step and the second cleaning step during the etching process of the substrate to be processed, it is possible to prevent the reaction product from being deposited in the processing chamber. The first cleaning step and the second cleaning step are preferably performed every time one etching process is performed on the substrate to be processed, but may be performed every several times. As described above, by repeating the cleaning step, it is possible to perform effective plasma cleaning in the case of etching a substrate to be processed containing a difficult-to-etch material. For example, when a substrate to be processed containing aluminum oxide is etched, even if, for example, aluminum remains in the first cleaning step and aluminum remaining in the second cleaning step is fluorinated, the next first cleaning step Fluorinated aluminum can be removed by the reducing action of the gas.

  Further, when a reaction product that cannot be efficiently removed by the first and second cleaning steps remains, a third cleaning step suitable for removal of the reaction product is performed after the second cleaning step or the first cleaning step. It may be added before the cleaning step.

  Further, a process called seasoning may be added following the cleaning. Here, seasoning is a process of coating an appropriate film on the inside of the processing chamber in order to form a processing chamber atmosphere suitable for the etching process.

[Example 1]
A cleaning process in the case of etching a substrate to be processed that includes a compound (aluminum oxide) containing oxygen atoms and aluminum atoms and silicon will be described.

(1) Etching treatment Aluminum oxide (Al ₂ O ₃ ) and boron trichloride (BCl ₃ ) react to produce aluminum chloride (AlCl ₃ ) and boron oxide (B ₂ O ₃ ). Chlorine (Cl ₂ ) produced by decomposition of boron trichloride (BCl ₃ ) in plasma reacts with silicon (Si) to produce silicon chloride (SiCl ₄ ). These reactions are generally expressed by the following formula.

Al ₂ O ₃ + 2BCl ₃ → 2AlCl ₃ + B ₂ O ₃ (Formula 1)
Si + 2Cl ₂ → SiCl ₄ (Formula 2)
FIG. 2 shows the result of evaluating the reactivity by thermodynamic calculation in order to confirm the above estimation. Here, thermodynamic calculation is to obtain a thermodynamically most stable combination of substances under a certain temperature and pressure, and is one of methods for predicting a chemical reaction occurring between substances.

  FIG. 2 shows the result of thermodynamic calculation in the case of reacting 4 mol of boron trichloride with 1 mol of aluminum oxide. The pressure was 1 Pa. Here, a thermodynamically stable state can be considered qualitatively to indicate an equilibrium state in which all possible reactions have occurred. Boron trichloride and aluminum oxide can react chemically to form compounds containing chlorine or boron or oxygen or aluminum. Moreover, there is a possibility that the reaction does not occur chemically.

In order to judge what kind of chemical reaction occurs, it is possible to list compounds that may be generated by a combination of each element, and to obtain a thermodynamically most stable combination of compounds. In FIG. 2, for example, around 400 ° C., boron trichloride (BCl ₃ ) is about 3.2 mol, aluminum trichloride (expressed as AlCl ₃ (gas)) is about 0.8 mol, and Al ₄ B ₂ O _9. Is about 0.3 mol. That is, when 4 mol of boron trichloride and 1 mol of aluminum oxide are completely reacted, the compound is produced in the amount described above. This situation is a reaction formula,
2BCl ₃ + 3Al ₂ O ₃ → 2AlCl ₃ + Al ₄ B ₂ O ₉ formula (1-1)
Can be expressed. Here, Al ₄ B ₂ O ₉ is a structure in which one aluminum oxide ( ₂ Al ₂ O ₃ ) and one boron oxide (B ₂ O ₃ ) are combined as a structure, and the formula (1-1) is a formula (1) It turns out that it is the same.

Thus, the reaction between boron trichloride and aluminum oxide can be predicted by thermodynamic calculation. Further, it shows that the etching reaction proceeds when aluminum chloride (AlCl ₃ , Al ₂ Cl ₆ ) is generated and volatilized.

FIG. 2 shows a thermodynamically stable combination of 4 mol of boron trichloride and 1 mol of aluminum oxide at a pressure of 1 Pa. In addition, it shows the possibility that gaseous aluminum chloride (AlCl ₃ , Al ₂ Cl ₆ ) is generated at room temperature or higher, and shows the possibility that the etching reaction of aluminum oxide proceeds when these are discharged in the processing chamber. Yes.

Similarly, the reaction between silicon and chlorine was evaluated by thermodynamic calculation. The result is shown in FIG. Here, 1 mol of silicon (Si), 4 mol of chlorine (Cl 2), and a pressure of 1 Pa were used. This resulted in the formation of silicon tetrachloride (SiCl ₄ ) over the calculated total temperature range. That is, it can be seen that silicon tetrachloride volatilizes as a gas and the etching reaction proceeds.

(2) Cleaning process Similarly, thermodynamic calculation was used to estimate the reaction in the processing chamber during cleaning. FIG. 4 shows the case where aluminum chloride and sulfur hexafluoride are 1 mol and 5 mol, respectively, and the pressure is 1 Pa. FIG. 5 shows the case where silicon tetrachloride and sulfur hexafluoride are 1 mol and 5 mol, respectively, and the pressure is 1 Pa. The result of thermodynamic calculation is shown.

4 that aluminum chloride (AlCl ₃ ) and sulfur hexafluoride (SF ₆ ) remaining in the processing chamber react to produce aluminum fluoride (AlF ₃ ). Aluminum fluoride (AlF ₃ ) has a low vapor pressure and low volatility, and thus tends to remain as a solid in the processing chamber. Further, from FIG. 5, the silicon chloride (SiCl ₄ ) remaining in the processing chamber reacts with sulfur hexafluoride (SF ₆ ) to generate silicon fluoride (SiF ₄ ), which is gasified and discharged from the processing chamber. It can be seen that it is discharged. .

AlCl ₃ + 3SF ₆ → AlF ₃ + 3SF ₅ Cl (Formula 3)
SiCl ₄ + 4SF ₆ → SiF ₄ + 4SF ₅ Cl (Formula 4)
From the above, if aluminum chloride is removed by another cleaning process before the cleaning process, the formation of aluminum fluoride can be prevented.

  Therefore, we decided to add cleaning with chlorine gas before the cleaning process. In addition, the cleaning with aluminum fluoride is performed in consideration of the case where aluminum chloride is not completely removed even with cleaning with this newly added chlorine-based gas, and aluminum fluoride is formed during the cleaning of sulfur hexafluoride. investigated.

First, a gas that can remove aluminum fluoride was searched by thermodynamic calculation. As a result, it was found that cleaning can be performed with a plasma of a gas containing boron trichloride and silicon tetrachloride. The results are shown in FIGS. 6 and 7, respectively. The pressure at this time was 1 Pa. The reaction at this time is, for example,
3AlF ₃ + 2BCl ₃ → 2AlCl ₃ + BF ₃ + BClF ₂ + BCl ₂ F (Formula 5)
AlF ₃ + SiCl ₄ → AlCl ₃ + SiF ₄ (Formula 6)
Can be estimated. That is, it can be interpreted that fluorine is extracted and salified by the reducing action of boron trichloride and silicon tetrachloride. Here, since aluminum chloride volatilizes, it is cleaned.

  It can be seen that when boron trichloride shown in FIG. 6 is used, aluminum fluoride begins to gasify from around 200 ° C. It can be seen that when silicon tetrachloride shown in FIG. 7 is used, gasification starts from around 300 ° C.

  It can be seen that when boron trichloride is used, the temperature at which gasification is possible is lower, which is advantageous for removing aluminum fluoride. Therefore, a cleaning process using a gas system containing boron trichloride or silicon tetrachloride is performed before the cleaning process, and a cleaning process including a fluorine-based gas such as sulfur hexafluoride is performed after the cleaning process.

Another effect of performing cleaning including a fluorine-based gas such as sulfur hexafluoride in the subsequent stage is a boron oxide removal effect. Boron oxide (B ₂ O ₃ ) in the formula (1) is a solid and is easily deposited in the processing chamber. Similarly, it was found by thermodynamic calculation that boron oxide can be cleaned with a fluorine-based gas such as sulfur hexafluoride, for example, by the reaction shown in Formula (7).

B ₂ O ₃ + 2SF ₆ → 2BF ₃ + SOF ₄ + SO ₂ F ₂ (Formula 7)
FIG. 8 shows the results of thermodynamic calculation when 3 mol of sulfur hexafluoride is reacted at a pressure of 1 Pa to 1 mol of boron oxide. In FIG. 8, sulfur hexafluoride (expressed as SF ₆ ) and SO ₂ F ₂ overlap. It can also be seen that boron oxide is cleaned as boron fluoride.

In the case where aluminum oxide (Al ₂ O ₃ ) is etched using boron trichloride (BCl ₃ ) having a reducing action during the etching process, aluminum fluoride (AlF ₃ ) is already contained in the processing chamber at the start of the etching process. In this case, aluminum fluoride (AlF ₃ ) remaining due to the action of boron trichloride (BCl ₃ ) may react with aluminum chloride (AlCl ₃ ) and be cleaned. However, when a substrate containing aluminum oxide (Al ₂ O ₃ ) is processed as the substrate to be processed, the amount of boron trichloride (BCl ₃ ) in the processing chamber is larger than the total amount of aluminum oxide and aluminum fluoride in the processing chamber. In some cases, the cleaning effect during the above-described etching process may not be exhibited due to a relative shortage, and this is considered to be equivalent to this case.

[Example 2]
In the above, the case where the substrate to be processed containing silicon and the compound containing oxygen atoms and aluminum atoms is etched has been described, but the same applies to other materials when fluoride is hardly vaporized and chloride is easily vaporized. The cleaning method can be applied.

  Hafnium is known as a new material that is expected to be used for semiconductor circuit elements in the future, and like aluminum, fluoride is not easily vaporized and chloride is easily vaporized.

  This material may also be cleaned with a chlorine-based gas before the cleaning, and cleaned with a fluorine-based gas after the cleaning. It is desirable to remove the fluoride by chlorination using a reducing gas such as boron trichloride or silicon tetrachloride when cleaning the chlorine-based gas.

Next, a case where a material containing hafnium (Hf) is etched will be described. Hafnium is considered to have a high possibility that its oxide (HfO ₂ ) is used for a gate insulating film of a transistor structure for next-generation integrated circuits. Hafnium oxide (HfO ₂ ) can be etched using boron trichloride (BCl ₃ ), and hafnium chloride (HfCl ₄ ) is generated as a reaction product. The corresponding thermodynamic calculation results are shown in FIG.

In FIG. 9, 1 mol of hafnium oxide (HfO ₂ ), 3 mol of boron trichloride (BCl ₃ ), and 1 Pa are reacted. In this case, it can be seen that the following reaction is expected at a temperature of about 100 ° C. or higher.

3HfO ₂ + 4BCl ₃ → 3HfCl ₄ + 2B ₂ O ₃ (Formula 7)
When plasma cleaning is performed with a fluorine-based gas such as sulfur hexafluoride with hafnium chloride remaining, hafnium fluoride is generated and easily deposited in the processing chamber. The result of the thermodynamic calculation is shown in FIG. In FIG. 10, 1 mol of hafnium chloride (HfCl ₄ ), ₆ mol of sulfur hexafluoride (SF ₆ ), and a pressure of 1 Pa were reacted. In this case, it is presumed that the reaction shown in the following formula 8 occurs.

HfCl ₄ + 4SF ₆ → HfF ₄ + 4SF ₅ Cl (Formula 8)
In FIG. 10, hafnium fluoride (indicated as HfF ₄ ) turns into a gas at a temperature of about 500 ° C. or higher, but it is solid at a temperature lower than this and is likely to remain in the processing chamber. .

  As a result of the examination, it was found that hafnium fluoride can be plasma cleaned with a gas containing boron trichloride or silicon tetrachloride. Therefore, cleaning is performed with a gas containing boron trichloride or silicon tetrachloride before the cleaning process, and plasma cleaning is performed with a gas system containing fluorine such as sulfur hexafluoride at the subsequent stage.

  In this case, it can be estimated that the following reaction is taking place. FIG. 11 shows the thermodynamic calculation results of the reaction between hafnium fluoride and boron trichloride (in the case of 1 mol of hafnium fluoride, 5 mol of boron trichloride, and a pressure of 1 Pa). FIG. 12 shows the thermodynamic calculation results of the reaction between hafnium fluoride and silicon tetrachloride (in the case of 1 mol of hafnium fluoride, 3 mol of silicon tetrachloride, and a pressure of 1 Pa).

  11 and 12, it can be seen that hafnium fluoride reacts with hafnium chloride, and that hafnium chloride is vaporized and cleaned at a temperature of about 90 ° C. or higher. In this case, for example, it can be estimated that the reactions of Formulas 9 and 10 are occurring.

3HfF ₄ + 4BCl ₃ → 3HfCl ₄ + 4BF ₃ (Formula 9)
HfF ₄ + SiCl ₄ → HfCl ₄ + SiF ₄ (Formula 10)
FIG. 13 is a diagram for explaining the flow of control signals in the plasma etching apparatus. The control device 124 is configured by a computer, includes a memory unit 121, a control unit 122, and a console unit 123, and transmits and receives control signals to and from each unit configuring the plasma etching apparatus 125. An operator of the plasma etching apparatus 125 can grasp the apparatus state from the console unit 123 via the control unit 122 and can control the apparatus state.

  The memory unit 121 can store a processing procedure (recipe) of the plasma etching apparatus 125, and the control device 124 performs a plasma etching process on the substrate to be processed according to the processing procedure. The control unit 122 transmits / receives information to / from the memory unit 121 and the console unit 123, and also includes a bias power source 114, a matching unit 113, a vacuum exhaust unit 117, a gas supply unit 116, a microwave power source 101, a matching unit 102, and various monitors. Information is transmitted to and received from the apparatus 118, the substrate transfer means 119, and various power sources 120. Here, the various monitor devices are a processing chamber temperature measuring device, a processing chamber pressure measuring device, and the like. The various power sources include an electrostatic chuck power source for adsorbing the substrate to be processed, a magnetic field generating coil power source for supplying a static magnetic field into the processing chamber, and the like.

  FIG. 15 is a diagram illustrating signals transmitted and received between the constituent elements constituting the control unit 122 and the etching apparatus 125. A setting value is sent to each component from the control unit 122, and a monitor value or a signal indicating the state of each component is sent to the control unit 122 from each component.

  Each signal transmitted and received is a digital signal or an analog signal. A signal transmission path between each component and the control unit 122 is an input signal path to the control unit 122, an output signal path indicating a setting value from the control unit 122, and the like. It consists of three types of control signal paths.

  For example, in the case of transmission / reception between the microwave generation device 101 constituting the plasma generation means and the control unit 122, the microwave generation device 101 sends an analog signal having a voltage proportional to the output of the microwave generation device 101 to the control unit 122. Always sending. In addition, the control unit 122 sends an analog signal having a voltage proportional to the microwave output set in the microwave generator 101 to the microwave generator 101.

  The control unit 122 further sends a control signal (on / off signal) for controlling on / off of the microwave output to the microwave generator 101 as a control signal for controlling the microwave generator 101, and the microwave generator 101 outputs the microwave output. When the control signal for turning on / off is turned on, the setting signal for the microwave output becomes valid, and the output microwave according to the setting signal is output. In addition, the microwave generation device 101 monitors the output of the microwave generation device 101 and transmits the monitor result to the control unit 101. In addition, the microwave generation apparatus 101 sends a signal indicating that the apparatus state of the microwave generation apparatus 101 is normal or abnormal to the control unit.

  The signals transmitted and received between the microwave generator 101 and the control unit 122 have been described above. However, between the gas supply unit 116 and the control unit 122, between the vacuum evacuation unit and the control unit 122, and the substrate transfer unit 119 Similarly, between the control units 122, a setting signal and an on / off control signal are transmitted from the control unit to the gas supply unit, the vacuum evacuation unit, and the substrate transporting unit, respectively, and the gas supply unit, the vacuum evacuation unit, and the processing target are transmitted. The substrate transfer means generates outputs according to the setting signal and the on / off control signal, respectively. Further, the gas supply means, the vacuum exhaust means, and the substrate transport means send the monitoring result and a signal indicating normality or abnormality of the apparatus to the control unit, respectively.

  As described above, the control unit 122 controls the gas supply amount of the gas supply unit that supplies a plurality of processing gases to the decompression processing chamber, and the function of controlling the gas exhaust amount by the vacuum exhaust unit that exhausts the decompression processing chamber. , A function of carrying the substrate into and out of the reduced pressure processing chamber, and a function of controlling plasma generating means for generating plasma by supplying high frequency energy to the processing gas supplied into the reduced pressure processing chamber.

  FIG. 14 is a diagram for explaining the flow of plasma processing performed on the substrate to be processed. First, in step S101, the transfer means transfers a substrate to be processed containing, for example, a compound containing oxygen atoms and aluminum and silicon into the reduced pressure processing chamber, and places the substrate on the substrate electrode. In step S102, the gas supply unit and the plasma generation unit introduce reactive gas into the plasma processing chamber, and further input high-frequency power into the plasma processing chamber. Thereby, the introduced reactive gas is turned into plasma, and further, this is reacted with the substrate to be processed placed on the substrate to be processed, thereby etching the substrate to be processed. In step S <b> 103, the transfer means carries the substrate that has undergone the plasma processing out of the decompression processing chamber. In step S104, for example, a gas containing chlorine such as boron trichloride is supplied to the reduced pressure processing chamber to generate plasma in the reduced pressure processing chamber to perform first plasma cleaning. In step S105, for example, a gas containing fluorine is supplied into the reduced pressure processing chamber to generate plasma in the reduced pressure processing chamber to perform second plasma cleaning. In step S106, it is determined whether the predetermined number of processed sheets has been reached. If not, the next substrate to be processed is introduced and the process is repeated. If it has reached, the process is terminated.

  As described above, according to the embodiment of the present invention, cleaning is performed using a gas system containing boron trichloride or silicon tetrachloride in the previous stage of plasma cleaning after plasma etching, and using a fluorine-based gas in the subsequent stage. Perform cleaning.

  That is, aluminum oxide is vaporized and discharged as aluminum chloride by the first plasma cleaning (previous stage). Further, boron oxide generated by the first plasma cleaning is vaporized and discharged by the second plasma cleaning (later stage).

  When boron trichloride is used in the previous cleaning, the aluminum fluoride starts to gasify from around 200 ° C. That is, when boron trichloride is used, the temperature at which gasification is possible is low, which is advantageous for removing aluminum fluoride. Further, boron oxide can be removed by performing cleaning including a fluorine-based gas such as sulfur hexafluoride in the subsequent stage.

  The present invention is not limited to a microwave plasma generator as in the plasma etching apparatus shown in FIG. 1, but can also be applied to plasma etching apparatuses using other plasma generation methods.

It is a figure explaining the plasma etching apparatus used by this invention. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining a thermodynamic calculation result. It is a figure explaining the flow of the control signal in a plasma etching apparatus. It is a figure explaining the flow of the plasma processing performed to a to-be-processed substrate. It is a figure which shows the signal transmitted / received between each component which comprises a control part and an etching apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Microwave generator 102 Automatic matching machine 103 Rectangular waveguide 104 Rectangular-circular waveguide converter 105 Circular waveguide 106 Hollow part 107 Electromagnetic wave introduction window 108 Gas dispersion plate 109 Gas supply apparatus 110 Processing chamber 111 Substrate to be processed 112 Substrate electrode 113 Automatic alignment machine 114 Substrate bias power supply 115 Static magnetic field generator 116 Gas supply means 117 Vacuum exhaust means 118 Monitor 119 Substrate transport means 120 Power supply 121 Memory part 122 Control part 123 Console

Claims (4)

A decompression chamber, a gas supply means for supplying a treatment gas to the decompression chamber, and a substrate electrode for mounting and holding a substrate to be treated containing a compound containing oxygen atoms and aluminum and silicon in the decompression chamber the Te decompression in the processing chamber is supplied to the processing gas by supplying a high-frequency energy with a plasma generation means for generating plasma by the generated plasma subjected to plasma etching process on the target substrate plasma processing method odor,
A first plasma cleaning process for carrying out plasma cleaning of the reduced pressure processing chamber by supplying a gas containing silicon tetrachloride to the reduced pressure processing chamber after unloading the substrate to be processed after the plasma etching processing has been completed; plasma processing method characterized in that it comprises a second plasma cleaning process of plasma cleaning said vacuum processing chamber a gas containing fluorine after the first plasma cleaning process is supplied to the decompression processing chamber. A reduced pressure processing chamber; a gas supply means for supplying a processing gas to the reduced pressure processing chamber; and a substrate electrode for mounting and holding a substrate to be processed containing a compound containing oxygen atoms and hafnium and silicon in the reduced pressure processing chamber. the Te decompression in the processing chamber is supplied to the processing gas by supplying a high-frequency energy with a plasma generation means for generating plasma by the generated plasma subjected to plasma etching process on the target substrate plasma processing method odor,
After the plasma etching process has been carried out the substrate to be processed has been completed in a vacuum processing outside, a first plasma cleaning process of plasma cleaning the inside of the vacuum treatment chamber by supplying a gas containing silicon tetrachloride in a vacuum processing chamber, plasma processing method characterized in that it comprises a second plasma cleaning process of plasma cleaning the inside of the vacuum treatment chamber a gas containing fluorine after the first plasma cleaning management is supplied to the decompression processing chamber. A function of controlling a gas supply amount of a gas supply means for supplying a plurality of process gases to the decompression process chamber, a function of controlling a gas exhaust amount by a vacuum exhaust means for exhausting the decompression process chamber, and the supply to the decompression process chamber ability to supply high-frequency energy to the process gas to control the plasma generation means for generating a plasma, and the vacuum treatment chamber compound containing an oxygen atom and aluminum in and carries the substrate to be processed comprising a silicon treated treated substrate Te computer-readable recording medium smell a program for executing the function of controlling the target substrate conveying means for carrying out the computer,
The function of controlling the gas supply amount and the function of controlling the plasma generating means are characterized in that after the substrate to be processed after the plasma processing is carried out of the decompression processing chamber, a gas containing silicon tetrachloride is supplied to the decompression processing chamber. a function of applying a first plasma cleaning process of plasma cleaning the inside of vacuum processing chamber, the plasma cleaning in said vacuum processing chamber a gas containing fluorine after the first plasma cleaning process is supplied to the decompression processing chamber A computer-readable recording medium , comprising: a function of performing a plasma cleaning process. A function of controlling a gas supply amount of a gas supply means for supplying a plurality of process gases to the decompression process chamber, a function of controlling a gas exhaust amount by a vacuum exhaust means for exhausting the decompression process chamber, and the supply to the decompression process chamber A function of controlling plasma generation means for generating plasma by supplying high-frequency energy to the processing gas, and a substrate to be processed that has been processed by carrying a substrate containing oxygen and a compound containing hafnium and silicon into the reduced pressure processing chamber In a computer-readable recording medium on which a program for causing a computer to execute a function of controlling a substrate transfer means for carrying out a substrate is recorded ,
Function for controlling the function and plasma generation means for controlling the gas supply amount, after unloading the substrate to be processed plasma processing is completed in a vacuum processing outside, silicon tetrachloride to a vacuum processing chamber
First a function of performing a plasma cleaning process of plasma cleaning said vacuum processing chamber by supplying a gas containing said reduced pressure supplying a gas containing fluorine after the first plasma cleaning process in the decompression processing chamber second computer readable recording medium which comprises a function for performing a plasma cleaning process of plasma cleaning the processing chamber.