JP2019216140A - Deposition device and cleaning method in deposition device - Google Patents

Abstract

To provide a technique capable of restraining breakdown of lower electrode, in cleaning not using a dummy wafer.SOLUTION: A deposition device comprises a processing container capable of evacuation, a lower electrode, an upper electrode, a gas supply part, and a voltage application part. A processed board can be placed on the lower electrode. The upper electrode is placed oppositely to the lower electrode in the processing container. The gas supply part supplies cleaning gas to be plasmatized, in a processing space between the upper and lower electrodes, to clean off reaction products adhered, during deposition, to an inner surface of the processing container. The voltage application part applies a DC pulse voltage to the upper electrode, when the cleaning gas is supplied to the processing space in a state where the processed board is not placed on the lower electrode.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a film forming apparatus and a cleaning method in the film forming apparatus.

  In a plasma process performed on the surface of a semiconductor wafer in a semiconductor device manufacturing process, as the number of processes increases, a reaction product adheres to an inner wall of a chamber (processing vessel), a susceptor on which the semiconductor wafer is placed, or the like. Increases the amount of adhering. When the amount of the reaction product attached increases, the processing environment changes, so that the uniformity of the processing between the semiconductor wafers may deteriorate. In addition, an increase in the amount of the reaction product attached becomes a cause of generation of particles. Therefore, the inside of the chamber is cleaned with plasma obtained by converting the cleaning gas into plasma.

JP 2012-204644 A

  When cleaning the inside of the chamber with plasma, cleaning with plasma may be performed with a dummy wafer placed on the susceptor to prevent damage to the surface of the susceptor. However, in the cleaning using the dummy wafer, it is necessary to carry the dummy wafer into the chamber and carry out the dummy wafer from the chamber, so that the throughput is lowered. Further, since the cost of the dummy wafer is high, if the cleaning using the dummy wafer is performed, the manufacturing cost of the semiconductor device is increased.

  Therefore, cleaning may be performed without using a dummy wafer. However, in cleaning without using a dummy wafer, the surface of the susceptor is exposed to plasma, so that the surface of the susceptor becomes rough. When the degree of roughness of the susceptor surface increases, the state of heat transfer between the susceptor and the semiconductor wafer changes, and the process temperature of the semiconductor wafer may deviate from the set temperature. For this reason, when cleaning without using a dummy wafer is performed, the susceptor replacement frequency increases in order to maintain the process temperature of the semiconductor wafer at the set temperature. Since the susceptor is an expensive member, if the frequency of replacement of the susceptor increases, the manufacturing cost of the semiconductor device increases.

  The present disclosure provides a technique capable of suppressing damage to a susceptor used as a lower electrode in cleaning without using a dummy wafer.

  A film forming apparatus according to an embodiment of the present disclosure includes a processing container capable of evacuating, a lower electrode, an upper electrode, a gas supply unit, and a voltage application unit. A substrate to be processed can be placed on the lower electrode. The upper electrode is disposed to face the lower electrode in the processing container. The gas supply unit supplies plasma to the processing space with a cleaning gas that cleans reaction products adhering to the inside of the processing container during film formation by being converted into plasma in the processing space between the upper electrode and the lower electrode. The voltage application unit applies a DC pulse voltage to the upper electrode when the cleaning gas is supplied to the processing space in a state where the substrate to be processed is not placed on the lower electrode.

  According to the technology of the present disclosure, in cleaning without using a dummy wafer, damage to a susceptor used as a lower electrode can be suppressed.

FIG. 1 is a diagram illustrating a configuration example of a film forming apparatus according to the embodiment. FIG. 2 is a diagram illustrating an example of the high-frequency voltage according to the embodiment. FIG. 3 is a diagram illustrating an example of a DC pulse voltage according to the embodiment. FIG. 4 is a diagram illustrating an example of the superimposed voltage according to the embodiment. FIG. 5 is a diagram illustrating an example of the experimental result 1 in the comparative example. FIG. 6 is a diagram illustrating an example of the experimental result 1 in the comparative example. FIG. 7 is a diagram illustrating an example of the experimental result 2 in the comparative example. FIG. 8 is a diagram illustrating an example of the experimental result 2 in the comparative example. FIG. 9 is a diagram illustrating an example of the experimental result 1 in the embodiment. FIG. 10 is a diagram illustrating an example of the experimental result 1 in the embodiment. FIG. 11 is a diagram illustrating an example of the experimental result 2 in the embodiment. FIG. 12 is a diagram illustrating an example of the experimental result 2 in the embodiment.

  Hereinafter, embodiments of the technology of the present disclosure will be described with reference to the drawings.

<Configuration of film forming apparatus>
FIG. 1 is a diagram illustrating a configuration example of a film forming apparatus according to the embodiment. A film forming apparatus 1 shown in FIG. 1 is configured as a capacitively coupled parallel plate film forming apparatus.

  In FIG. 1, a film forming apparatus 1 has a chamber 10 which is a metal processing container made of, for example, aluminum or stainless steel. The chamber 10 is grounded for safety.

  In the chamber 10, a disk-shaped susceptor 12 is horizontally disposed. On the susceptor 12, a semiconductor wafer W as a substrate to be processed can be placed. The susceptor 12 also functions as a lower electrode. A gate valve 28 for opening and closing the loading / unloading port for the semiconductor wafer W is attached to the side wall of the chamber 10. The susceptor 12 is made of, for example, AlN ceramic and is supported by an insulating cylindrical support portion 14 that extends vertically upward from the bottom of the chamber 10.

  An annular exhaust passage 18 is formed between a conductive cylindrical support (inner wall) 16 extending vertically upward from the bottom of the chamber 10 along the outer periphery of the cylindrical support 14 and a side wall of the chamber 10. I have. An exhaust port 22 is provided at the bottom of the exhaust path 18.

  An exhaust device 26 is connected to the exhaust port 22 via an exhaust pipe 24. The exhaust device 26 has a vacuum pump such as a turbo molecular pump, for example, and depressurizes the processing space in the chamber 10 to a desired degree of vacuum. The inside of the chamber 10 is preferably maintained at a constant pressure in the range of, for example, 200 mTorr to 2500 mTorr.

  An impedance adjustment circuit 100 having a coil 101 and a variable capacitor 102 is electrically connected via a connecting rod 36 between the susceptor 12 used as a lower electrode and the ground.

  A semiconductor wafer W to be subjected to a film formation process is mounted on the susceptor 12, and a ring 38 is provided so as to surround the semiconductor wafer W. The ring 38 is made of a conductive material (for example, Ni, Al, etc.) and is detachably attached to the upper surface of the susceptor 12.

  Further, on the upper surface of the susceptor 12, an electrostatic chuck 40 for sucking a wafer is provided. The electrostatic chuck 40 is formed by sandwiching a sheet-like or mesh-like conductor between film-like or plate-like dielectrics. A DC power source 42 disposed outside the chamber 10 is electrically connected to the conductor in the electrostatic chuck 40 via an on / off switch 44 and a power supply line 46. The semiconductor wafer W is attracted and held on the electrostatic chuck 40 by the Coulomb force generated in the electrostatic chuck 40 by the DC voltage applied from the DC power source 42.

  An annular refrigerant chamber 48 extending in the circumferential direction is provided inside the susceptor 12. A coolant (for example, cooling water) at a predetermined temperature is circulated and supplied from the chiller unit (not shown) to the coolant chamber 48 via pipes 50 and 52. The temperature of the semiconductor wafer W on the electrostatic chuck 40 is controlled by controlling the temperature of the coolant. Further, in order to increase the temperature accuracy of the semiconductor wafer W, a heat transfer gas (for example, He gas) from a heat transfer gas supply unit (not shown) passes through the gas supply pipe 51 and the gas passage 56 in the susceptor 12. Then, it is supplied between the electrostatic chuck 40 and the semiconductor wafer W.

  A disk-shaped inner upper electrode 60 and a ring-shaped outer upper electrode 62 are provided concentrically on the ceiling of the chamber 10 so as to face (ie, face) the susceptor 12 in parallel. As a preferred size in the radial direction, the inner upper electrode 60 has the same diameter (diameter) as the semiconductor wafer W, and the outer upper electrode 62 has the same diameter (inner diameter / outer diameter) as the ring 38. Yes. However, the inner upper electrode 60 and the outer upper electrode 62 are electrically insulated from each other. A ring-shaped insulator 63 made of, for example, ceramic is inserted between the two electrodes 60 and 62.

  The inner upper electrode 60 has an electrode plate 64 facing directly in front of the susceptor 12, and an electrode support 66 for detachably supporting the electrode plate 64 from behind (above). As the material of the electrode plate 64, a conductive material such as Ni or Al is preferable. The electrode support 66 is made of alumite-treated aluminum, for example. The outer upper electrode 62 also has an electrode plate 68 facing the susceptor 12 and an electrode support 70 that detachably supports the electrode plate 68 from behind (upper) thereof. The electrode plate 68 and the electrode support 70 are preferably made of the same material as the electrode plate 64 and the electrode support 66, respectively. Hereinafter, the inner upper electrode 60 and the outer upper electrode 62 may be collectively referred to as “upper electrodes 60, 62”. Thus, in the film forming apparatus 1, the disk-shaped susceptor 12 (that is, the lower electrode) and the disk-shaped upper electrodes 60 and 62 face each other in parallel.

  In the present embodiment, the case where the upper electrodes 60 and 62 are composed of two members, the inner upper electrode 60 and the outer upper electrode 62, has been described as an example. However, the upper electrode may be composed of one member.

  The inner upper electrode 60 is also used as a shower head in order to supply a processing gas to the processing space PS set between the upper electrodes 60 and 62 and the susceptor 12. More specifically, a gas diffusion chamber 72 is provided inside the electrode support 66, and a number of gas discharge holes 74 penetrating from the gas diffusion chamber 72 toward the susceptor 12 are formed in the electrode support 66 and the electrode plate 64. A gas supply pipe 78 extending from the gas supply unit 76 is connected to the gas introduction port 72 a provided in the upper part of the gas diffusion chamber 72. Note that a shower head may be provided not only on the inner upper electrode 60 but also on the outer upper electrode 62.

  A voltage application unit 5 that outputs an applied voltage is disposed outside the chamber 10. The voltage application unit 5 is connected to the upper electrodes 60 and 62 via the power supply line 88. The voltage application unit 5 includes a high frequency power source 30, a matching unit 34, a variable DC power source 80, a pulse generator 84, a filter 86, a superimposing unit 91, and an on / off switch 92.

  The high-frequency power supply 30 generates a high-frequency AC voltage (hereinafter sometimes referred to as a “high-frequency voltage”), and supplies the generated high-frequency voltage to the superimposing device 91 via the matching unit 34 and the on / off switch 92. I do. When the on / off switch 92 is on, the high-frequency voltage is supplied to the superimposer 91, while when the on / off switch 92 is off, the high-frequency voltage is supplied to the superimposer 91. Not supplied. The frequency of the high frequency voltage generated by the high frequency power supply 30 is preferably, for example, 13 MHz or more.

  FIG. 2 is a diagram illustrating an example of the high-frequency voltage according to the embodiment. As shown in FIG. 2, the high-frequency power supply 30 generates a high-frequency voltage V1 of −250 V to 250 V with 0 V as a reference potential RP, for example. The matching unit 34 matches the impedance on the high frequency power supply 30 side and the impedance on the load (mainly electrodes, plasma, chamber) side.

  The output terminal of the variable DC power supply 80 is connected to the pulse generator 84, and the variable DC power supply 80 outputs a negative DC voltage (that is, a negative DC voltage) to the pulse generator 84. The pulse generator 84 uses a negative DC voltage input from the variable DC power supply 80 to generate a rectangular wave DC pulse voltage (that is, a DC pulse voltage), and superimposes the generated DC pulse voltage via a filter 86. To the container 91. The frequency of the DC pulse voltage generated by the pulse generator 84 is preferably, for example, 10 kHz to 1 MHz. Further, the duty ratio of the DC pulse voltage generated by the pulse generator 84 is preferably 10% to 90%.

  FIG. 3 is a diagram illustrating an example of a DC pulse voltage according to the embodiment. As shown in FIG. 3, the pulse generator 84 generates, for example, a DC pulse voltage V <b> 2 of a rectangular wave of 0 V to −500 V. The filter 86 outputs the direct-current pulse voltage output from the pulse generator 84 to the superimposer 91 through, while passing the high-frequency voltage output from the high-frequency power supply 30 to the ground line and to the pulse generator 84 side. Is configured to not.

  The superimposer 91 superimposes the high-frequency voltage output from the high-frequency power supply 30 and the DC pulse voltage output from the pulse generator 84 to thereby superimpose the high-frequency voltage and the DC pulse voltage (hereinafter, “voltage”). Superimposed voltage). The generated superimposed voltage is applied to the upper electrodes 60 and 62 via the power supply line 88. The superimposer 91 is an example of a voltage superimposing unit.

  FIG. 4 is a diagram illustrating an example of the superimposed voltage according to the embodiment. When the high-frequency voltage V1 shown in FIG. 2 and the DC pulse voltage V2 shown in FIG. 3 are superimposed, a superimposed voltage V3 shown in FIG. 4 is generated. By superimposing the direct-current pulse voltage on the high-frequency voltage, as shown in FIG. 4, in the superimposed voltage V3, the high-frequency voltage V1 (FIG. 2) is matched to the waveform of the rectangular DC pulse voltage V2 (FIG. 3). The reference potential RP periodically and alternately changes with time. That is, when the on / off switch 92 is turned on, the voltage application unit 5 outputs a high-frequency voltage that changes in a pulse shape (that is, a rectangular wave shape).

  As described above, when the on / off switch 92 is on, the high-frequency voltage output from the matching unit 34 is supplied to the superimposer 91, so that the superimposer 91 outputs the superimposed voltage. On the other hand, when the on / off switch 92 is off, the high-frequency voltage output from the matching unit 34 is not supplied to the superimposer 91, so the DC pulse voltage output from the filter 86 is used as it is. Is output from.

  A ring-shaped ground part 96 made of a conductive material such as Ni or Al is attached to an appropriate position facing the processing space PS in the chamber 10 (for example, radially outside the outer upper electrode 62). . The ground part 96 is attached to a ring-shaped insulator 98 made of, for example, ceramic, is connected to the ceiling wall of the chamber 10, and is grounded through the chamber 10. When a superimposed voltage or a DC pulse voltage is applied from the voltage application unit 5 to the upper electrodes 60 and 62 during the plasma processing, an electron current flows between the upper electrodes 60 and 62 and the ground part 96 via the plasma. It has become.

  The operation of each component in the film forming apparatus 1 and the operation (sequence) of the entire film forming apparatus 1 are controlled by a control unit (not shown). For example, the operations of the exhaust device 26, the high frequency power supply 30, the on / off switch 44, 92, the gas supply unit 76, the chiller unit (not shown), the heat transfer gas supply unit (not shown), etc. (Not shown). An example of the control unit is a microcomputer.

<Film forming process in film forming apparatus>
In order to perform film formation in the film forming apparatus 1, first, the gate valve 28 is opened, and the semiconductor wafer W to be processed is loaded into the chamber 10 and placed on the electrostatic chuck 40.

  Next, the on / off switch 44 is turned on, and the semiconductor wafer W is suction-held on the electrostatic chuck 40 by the electrostatic suction force.

  Then, a film forming source gas is introduced into the chamber 10 at a predetermined flow rate as a processing gas from the gas supply unit 76, and the pressure in the chamber 10 is adjusted to a set value by the exhaust device 26.

  Further, the high frequency power supply 30, the variable DC power supply 80, and the on / off switch 92 are turned on, and the superimposed voltage is applied to the upper electrodes 60 and 62. Further, a heat transfer gas is supplied between the electrostatic chuck 40 and the semiconductor wafer W.

The film-forming source gas discharged from the inner upper electrode 60 is turned into plasma in the processing space PS by discharge between the upper electrodes 60 and 62 and the susceptor 12 used as the lower electrode, and radicals and ions contained in this plasma. As a result, a film is formed on the surface of the semiconductor wafer W. By using, for example, TEOS (Si (OC ₂ H ₅ )) gas, Ar gas, or O ₂ gas as the film forming source gas, an insulating film such as a SiO 2 film is formed on the surface of the semiconductor wafer W.

  Each time the number of semiconductor wafers W on which the film forming process is performed reaches a predetermined number, a cleaning process in the chamber 10 is performed.

<Cleaning process in film forming device>
Since no dummy wafer is used in the cleaning process according to the embodiment, the upper surface of the susceptor 12 (that is, the upper surface of the electrostatic chuck 40) is exposed to the processing space PS at the start of the cleaning process. Further, reaction products generated by the film forming process adhere to the inner wall of the chamber 10, the ring 38, and the like around the mounting region of the semiconductor wafer W in the susceptor 12.

  In a state where the upper surface of the susceptor 12 is exposed to the processing space PS, a cleaning gas is introduced into the chamber 10 as a processing gas at a predetermined flow rate from the gas supply unit 76, and the pressure in the chamber 10 is set to a set value by the exhaust device 26. Adjust to. The on / off switch 44 is turned off. For example, NF 3 gas is used as the cleaning gas. As the cleaning gas, for example, CF4 gas, C2F6 gas, CIF3 gas, or the like may be used in addition to the NF3 gas. In order to stabilize the plasma, Ar gas is introduced into the chamber 10 at a predetermined flow rate and mixed with the cleaning gas.

  For example, before introducing NF3 gas into the chamber 10, Ar gas at a flow rate of 3 slm is introduced into the chamber 10 to ignite plasma. After the plasma is ignited, the flow rate of Ar gas is increased from 3 slm to 9 slm over about 15 seconds. Then, the flow rate of NF3 gas is increased from 0 slm to 2 slm over about 15 seconds.

  Further, at the time when the Ar gas is introduced into the chamber 10, the variable DC power supply 80 is turned on while the on / off switch 92 is turned off, and a DC pulse voltage is applied to the upper electrodes 60 and 62.

  The cleaning gas (for example, NF3 gas) discharged from the inner upper electrode 60 is turned into plasma in the processing space PS by discharge between the upper electrodes 60 and 62 and the susceptor 12 used as the lower electrode. Then, the reaction product adhering in the chamber 10 becomes a fluoride having a high vapor pressure and is discharged out of the chamber 10 by radicals and ions contained in the plasma. The cleaning process is performed for 1 minute, for example.

<Experimental result>
As an example, experimental results when Ar / O 2 gas is introduced into the chamber 10 as the processing gas are shown below. 5 and 6 are diagrams showing an example of the experimental result 1 in the comparative example. 7 and 8 are diagrams showing an example of the experimental result 2 in the comparative example. 9 and 10 are diagrams illustrating an example of the experimental result 1 in the embodiment. 11 and 12 are diagrams illustrating an example of the experimental result 2 in the embodiment.

  FIGS. 5, 6, 9 and 10 show the experimental results when the pressure inside the chamber 10 was set to 500 mTorr, and FIGS. 7, 8, 11 and 12 show the results when the pressure inside the chamber 10 was set to 1000 mTorr. The experimental result in the state where it performed is shown. FIGS. 5 to 8 show experimental results when a high-frequency voltage having a frequency of 40 MHz is applied to the upper electrodes 60 and 62, and FIGS. 9 to 12 show that the upper electrodes 60 and 62 have a duty ratio of 50% and a frequency of 500 kHz. 4 shows the experimental results when a DC pulse voltage was applied. 5, FIG. 7, FIG. 9 and FIG. 11 show the relationship between the distance d in the z direction (FIG. 1) and the plasma density, and FIG. 6, FIG. 8, FIG. 10 and FIG. The relationship with temperature is shown. The distance d indicates a distance from the upper surface of the susceptor 12 to the lower surfaces of the upper electrodes 60 and 62 with the upper surface of the susceptor 12 (that is, the upper surface of the electrostatic chuck 40) as a base point in the z direction (FIG. 1). FIGS. 5 to 12 show, as an example, experimental results when the distance d (that is, the gap between the electrodes) between the upper surface of the susceptor 12 and the lower surfaces of the upper electrodes 60 and 62 is 0.014 m. . 5, FIG. 7, FIG. 9, and FIG. 11, the density of electrons e, the density of O 2 + ions, the density of O − ions, and the density of Ar + ions are used as indices representing the plasma density.

<Experimental result 1 of comparative example 1 (FIGS. 5 and 6)>
When a high frequency voltage of 40 MHz is applied to the upper electrodes 60 and 62 with the pressure in the chamber 10 set to 500 mTorr, the upper surface of the susceptor 12 and the lower surface of the upper electrodes 60 and 62 are In the vicinity of the intermediate point, the density of negative ions (O-ions) increases. In addition, as shown in FIG. 6, the electron temperature increases both near the upper surface of the susceptor 12 and near the lower surfaces of the upper electrodes 60 and 62.

<Experimental result 2 of comparative example (FIGS. 7 and 8)>
When a high-frequency voltage having a frequency of 40 MHz is applied to the upper electrodes 60 and 62 in a state where the pressure in the chamber 10 is set at 1000 mTorr, similarly to FIG. In the vicinity of the middle of the above, the density of negative ions (O-ions) increases (FIG. 7). Similarly to FIG. 6, the electron temperature increases both near the upper surface of the susceptor 12 and near the lower surfaces of the upper electrodes 60 and 62 (FIG. 8).

<Experimental result 1 of embodiment (FIGS. 9 and 10)>
When a DC pulse voltage of a frequency of 500 kHz is applied to the upper electrodes 60 and 62 in a state where the pressure in the chamber 10 is set to 500 mTorr, as shown in FIG. ) Greatly decreases.

  Further, as shown in FIG. 10, the electron temperature near the upper surface of the susceptor 12 is greatly reduced while the electron temperature near the lower surfaces of the upper electrodes 60 and 62 is maintained at a high temperature as compared with FIG. That is, in the processing space PS, a region having a high electron temperature is unevenly distributed near the lower surfaces of the upper electrodes 60 and 62. Here, since the dissociation of the processing gas is promoted as the electron temperature is higher, the generation amount of plasma is increased, so that radicals contained in the plasma are increased. That is, when a DC pulse voltage having a frequency of 500 kHz is applied to the upper electrodes 60 and 62 in a state where the pressure in the chamber 10 is 500 mTorr, the region where the plasma exists is near the lower surfaces of the upper electrodes 60 and 62 as shown in FIG. To be localized.

<Experimental result 2 of embodiment (FIGS. 11 and 12)>
Even when a DC pulse voltage having a frequency of 500 kHz is applied to the upper electrodes 60 and 62 in a state where the pressure in the chamber 10 is 1000 mTorr, the experimental results shown in FIGS. 9 and 10 are the same. That is, as shown in FIG. 11, the density of negative ions (O-ions) is significantly reduced as compared with FIG. Further, as shown in FIG. 12, compared with FIG. 8, the electron temperature near the upper surface of the susceptor 12 is greatly lowered while the electron temperature near the lower surface of the upper electrodes 60 and 62 is maintained at a high temperature. That is, in the processing space PS, a region where the electron temperature is high is unevenly distributed near the lower surfaces of the upper electrodes 60 and 62, so that the plasma existence region is localized near the lower surfaces of the upper electrodes 60 and 62.

  By applying a DC pulse voltage to the upper electrodes 60 and 62 as in the above experimental results, negative ions can be sharply reduced as compared with a case where a high-frequency voltage is applied to the upper electrodes 60 and 62. Can reduce the degree of damage to the member.

  When a DC pulse voltage is applied to the upper electrodes 60 and 62, the electron temperature increases on the upper electrode 60 and 62 side, while the electron temperature decreases on the susceptor 12 side as the lower electrode. The lower the electron temperature, the smaller the degree of damage to the electrode. Therefore, damage to the susceptor 12 can be suppressed by reducing the electron temperature on the susceptor 12 side by applying a DC pulse voltage to the upper electrodes 60 and 62. That is, according to the present embodiment, it is possible to suppress damage to the susceptor 12 used as the lower electrode in cleaning without using a dummy wafer. Even if the degree of damage to the upper electrodes 60 and 62 increases as the electron temperature at the upper electrodes 60 and 62 increases, the upper electrodes 60 and 62 are less expensive members than the susceptor 12. Therefore, the increase in the manufacturing cost of the semiconductor device is only slight.

  On the other hand, when a DC pulse voltage is applied to the upper electrodes 60 and 62, damage to the susceptor 12 as the lower electrode can be suppressed, as shown in the above experimental results, while the plasma exists in the upper electrode 60 and 62. It is localized near the lower surface of 62. For this reason, when a small amount of plasma is generated, radicals contained in the plasma may not reach the susceptor 12 and the degree of cleaning of the susceptor 12 may be reduced.

  However, the higher the electron temperature, the more the dissociation of the processing gas is promoted, so that the amount of plasma generated increases, and as a result, radicals contained in the plasma increase. According to the above experimental results, when a DC pulse voltage is applied to the upper electrodes 60 and 62 (FIGS. 10 and 11), a high-frequency voltage is applied to the upper electrodes 60 and 62 (FIGS. 6 and 8). In comparison, the electron temperature on the susceptor 12 side decreases, while the electron temperature on the upper electrodes 60 and 62 side increases. Therefore, by applying a DC pulse voltage to the upper electrodes 60 and 62, dissociation of the processing gas is promoted immediately below the upper electrodes 60 and 62, and the amount of radicals generated is increased. That is, by applying a DC pulse voltage to the upper electrodes 60 and 62, a large amount of radicals can be generated near the upper electrodes 60 and 62. Since a large amount of radicals are generated in the vicinity of the upper electrodes 60 and 62, a part of the large amount of radicals can reach the susceptor 12, so that the susceptor 12 is also cleaned.

  As described above, by applying a DC pulse voltage to the upper electrodes 60 and 62 in the cleaning process of introducing a cleaning gas such as NF3 gas into the chamber 10, damage to the susceptor 12 used as the lower electrode is suppressed, The susceptor 12 can be cleaned.

  As described above, in the embodiment, the film forming apparatus 1 includes the chamber 10 capable of evacuating, the susceptor 12 used as the lower electrode, the upper electrodes 60 and 62, the gas supply unit 76, the voltage applying unit 5, Having. A semiconductor wafer W can be placed on the susceptor 12. The upper electrodes 60 and 62 are disposed in the chamber 10 so as to face the susceptor 12. The gas supply unit 76 is turned into plasma in the processing space PS between the upper electrodes 60 and 62 and the susceptor 12, thereby cleaning gas for cleaning reaction products adhering to the chamber 10 during film formation. To supply. The voltage application unit 5 applies a DC pulse voltage to the upper electrodes 60 and 62 when the cleaning gas is supplied to the processing space PS without the semiconductor wafer W being placed on the susceptor 12.

  By doing so, it is possible to perform cleaning on the susceptor 12 while suppressing damage to the susceptor 12 used as the lower electrode.

  In addition, in the embodiment, the gas supply unit 76 supplies the processing space PS with a film forming material gas that forms an insulating film on the surface of the semiconductor wafer W by being turned into plasma in the processing space PS during film formation.

  By doing so, it is possible to ashing the reaction products adhered to the inside of the chamber 10 by the cleaning process when the insulating film is formed on the surface of the semiconductor wafer W in the film forming process.

  The embodiments of the present disclosure are to be considered in all respects as illustrative and not restrictive. Indeed, the above embodiments may be implemented in various forms. The above-described embodiments may be omitted, replaced, and changed in various forms without departing from the scope and spirit of the claims.

  For example, during the cleaning process, the voltage applying unit 5 may apply a superimposed voltage to the upper electrodes 60 and 62. Thereby, since the superimposed voltage includes a high-frequency AC component, the ignitability of the processing gas during the cleaning process can be improved.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 5 Voltage application part 10 Chamber 12 Susceptor 60 Inner upper electrode 62 Outer upper electrode 76 Gas supply part

Claims (3)

A processing container capable of being evacuated;
A lower electrode on which a substrate to be processed can be placed in the processing container;
An upper electrode disposed opposite to the lower electrode in the processing vessel;
A gas supply unit that supplies a cleaning gas to the processing space for cleaning a reaction product that has been deposited in the processing container during film formation by being converted into plasma in the processing space between the upper electrode and the lower electrode; ,
A voltage applying unit that applies a DC pulse voltage to the upper electrode when the cleaning gas is supplied to the processing space in a state where the substrate to be processed is not placed on the lower electrode;
A film forming apparatus comprising: The gas supply unit supplies, to the processing space, a film forming source gas that forms plasma in the processing space to form an insulating film on the surface of the substrate to be processed during the film formation.
The film forming apparatus according to claim 1. A processing container capable of being evacuated;
A lower electrode on which a substrate to be processed can be placed in the processing container;
An upper electrode disposed opposite to the lower electrode in the processing vessel;
A cleaning method in a film forming apparatus comprising:
Supplying a cleaning gas to the processing space for cleaning a reaction product adhering to the inside of the processing container by forming a plasma in the processing space between the upper electrode and the lower electrode;
Applying a DC pulse voltage to the upper electrode when the cleaning gas is supplied to the processing space in a state where the substrate to be processed is not placed on the lower electrode;
A cleaning method.

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