Plasma processing apparatus and processing method

Abstract

To reduce energy of an ion injected into a bottom electrode without increasing energy of an ion injected into an upper electrode.SOLUTION: A plasma processing apparatus comprises: a processing container; a bottom electrode that is provided within the processing container; an upper electrode that is arranged to oppose to the bottom electrode; a gas supply unit that is configured to supply a processing gas between the upper electrode and the bottom electrode; a high-frequency power supply that is configured to generate plasma of a processing gas by applying high-frequency voltage to the upper electrode; and a voltage waveform shaping unit that is provided between the high-frequency power supply and the upper electrode, and is configured to perform shaping of a voltage waveform of high-frequency voltage to be output from the high-frequency power supply by converting a positive voltage component to a negative voltage component.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Exemplary embodiments of the present disclosure relate to plasma processing apparatus and methods. [Background technology]

[0002] Plasma processing is widely used for processing substrates such as semiconductor wafers. Patent Document 1 discloses a technique for generating a bias output wave in which the positive voltage component of a high-frequency voltage waveform of a fundamental frequency is reduced, thereby reducing the energy of ions irradiated onto the chamber body of a plasma processing apparatus. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-201611 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for reducing the energy of ions incident on a lower electrode without increasing the energy of ions incident on an upper electrode. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a processing vessel, a lower electrode, an upper electrode, a gas supply unit, a high frequency power supply, and a voltage waveform shaping unit. The lower electrode is provided inside the processing vessel. The upper electrode is disposed to face the lower electrode. The gas supply unit is configured to supply a processing gas between the upper electrode and the lower electrode. The high frequency power supply is configured to generate plasma of the processing gas by applying a high frequency voltage to the upper electrode. The voltage waveform shaping unit is provided between the high frequency power supply and the upper electrode, and is configured to shape the voltage waveform of the high frequency voltage output from the high frequency power supply by converting a positive voltage component into a negative voltage component. Effect of the Invention

[0006] According to one exemplary embodiment, the energy of ions incident on the lower electrode can be reduced without increasing the energy of ions incident on the upper electrode. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment; [Diagram 2] FIG. 4 is a diagram illustrating a configuration of a voltage waveform shaping unit according to an example. [Diagram 3] 11 is a diagram for explaining shaping of a voltage applied to an upper electrode. FIG. [Figure 4] 11 is a diagram for explaining shaping of a voltage applied to an upper electrode. FIG. [Diagram 5] 11 is a diagram for explaining shaping of a voltage applied to an upper electrode. FIG. [Figure 6] FIG. 13 is a diagram showing a configuration of a voltage waveform shaping unit according to another example. [Figure 7] FIG. 13 is a diagram showing a configuration of a voltage waveform shaping unit according to another example. [Figure 8] FIG. 13 is a diagram showing a configuration of a voltage waveform shaping unit according to another example. [Figure 9] FIG. 13 is a diagram showing a configuration of a lower electrode according to another example. [Figure 10]1 is a flow diagram illustrating a processing method according to an exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Various exemplary embodiments are described below.

[0009] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a processing vessel, a lower electrode, an upper electrode, a gas supply unit, a high frequency power supply, and a voltage waveform shaping unit. The lower electrode is provided inside the processing vessel. The upper electrode is disposed to face the lower electrode. The gas supply unit is configured to supply a processing gas between the upper electrode and the lower electrode. The high frequency power supply is configured to generate plasma of the processing gas by applying a high frequency voltage to the upper electrode. The voltage waveform shaping unit is provided between the high frequency power supply and the upper electrode, and is configured to shape the voltage waveform of the high frequency voltage output from the high frequency power supply by converting a positive voltage component into a negative voltage component.

[0010] Since the voltage waveform is shaped by full-wave rectification that converts positive voltage components into negative voltage components, the peak of the negative voltage component of the shaped voltage applied to the upper electrode is similar to the peak of the negative voltage component of the unshaped voltage (e.g., a sinusoidal voltage output by a high-frequency power supply). This makes it possible to reduce the sheath voltage on the lower electrode while suppressing an increase in the sheath voltage on the upper electrode. This makes it possible to suppress an increase in the energy of ions bombarding the upper electrode and reduce the energy of ions incident on the lower electrode.

[0011] In one exemplary embodiment, the plasma processing apparatus further comprises a showerhead, which introduces a process gas into the interior of the processing vessel, and the showerhead is an upper electrode.

[0012] In one exemplary embodiment, the plasma processing apparatus further includes a matching box, the matching box being electrically connected between the high frequency power supply and the voltage waveform shaping unit.

[0013] In one exemplary embodiment, the process gas includes gases used in forming a film and providing film precursors to a substrate disposed within the process vessel.

[0014] In one exemplary embodiment, the voltage waveform shaping unit includes a transformer, a first rectifier, and a second rectifier. The transformer includes a primary coil and a secondary coil. A high-frequency power source is electrically connected between two terminals of the primary coil. The secondary coil includes two coils connected in series. Each of the two terminals of the secondary coil is electrically connected to the cathode of the first rectifier and the cathode of the second rectifier. The connection point of the two coils of the secondary coil is electrically grounded. The anode of the first rectifier and the anode of the second rectifier are electrically connected to the upper electrode.

[0015] In one exemplary embodiment, the voltage waveform shaping unit includes a transformer and a diode bridge circuit. The transformer includes a primary coil and a secondary coil. A high-frequency power source is electrically connected between two terminals of the primary coil. The diode bridge circuit includes a first rectifier, a second rectifier, a third rectifier, and a fourth rectifier. The cathode of the first rectifier is electrically connected to the anode of the second rectifier. The anode of the first rectifier is electrically connected to the anode of the third rectifier. The cathode of the second rectifier is electrically connected to the cathode of the fourth rectifier. The cathode of the third rectifier is electrically connected to the anode of the fourth rectifier. The cathode of the first rectifier is electrically connected to the cathode of the third rectifier via the secondary coil. The anode of the first rectifier and the anode of the third rectifier are electrically connected to the upper electrode. The cathode of the second rectifier and the cathode of the fourth rectifier are electrically grounded.

[0016] In one exemplary embodiment, the voltage waveform shaping unit includes a diode bridge circuit. The diode bridge circuit includes a first rectifier, a second rectifier, a third rectifier, and a fourth rectifier. The cathode of the first rectifier is electrically connected to the anode of the second rectifier. The anode of the first rectifier is electrically connected to the anode of the third rectifier. The cathode of the second rectifier is electrically connected to the cathode of the fourth rectifier. The cathode of the third rectifier is electrically connected to the anode of the fourth rectifier. Two terminals of the high frequency power supply are electrically connected to the cathode of the first rectifier and the cathode of the third rectifier, respectively. The anode of the first rectifier and the anode of the third rectifier are electrically connected to the upper electrode. The cathode of the second rectifier and the cathode of the fourth rectifier are electrically grounded to the lower electrode.

[0017] In one exemplary embodiment, the voltage waveform shaping unit includes a transformer, a first switching element, and a second switching element. The transformer includes a primary coil and a secondary coil. A high-frequency power source is electrically connected between two terminals of the primary coil. The secondary coil includes two coils connected in series. Each of the two terminals of the secondary coil is electrically connected to the first switching element and the second switching element. A connection point of the two coils of the secondary coil is electrically grounded. Each of the two terminals of the secondary coil is electrically connected to the upper electrode via each of the first switching element and the second switching element. The first switching element and the second switching element are configured to cut off a current flowing from the secondary coil.

[0018] In one exemplary embodiment, the plasma processing apparatus further includes a substrate placement table disposed inside the processing chamber and configured to place a substrate thereon. The substrate placement table is a lower electrode and is an electrically grounded conductor.

[0019] In one exemplary embodiment, the plasma processing apparatus further includes a substrate mounting table and a ground electrode. The substrate mounting table is provided inside the processing chamber, and a substrate is mounted thereon. The ground electrode 2b is provided outside the substrate mounting table. The material of the substrate mounting table is an insulator. The ground electrode is a lower electrode and is an electrically grounded conductor.

[0020] In one exemplary embodiment, the substrate support material is ceramic.

[0021] In another exemplary embodiment, a processing method is provided. The processing method is a processing method for performing plasma processing on a substrate placed inside a processing vessel of a plasma processing apparatus. The processing method includes steps a, b, and c. Step a supplies a processing gas between an upper electrode and a lower electrode of the plasma processing apparatus. Step b shapes a voltage waveform of a high frequency voltage output from a high frequency power supply of the plasma processing apparatus by converting a positive voltage component into a negative voltage component. Step c applies the shaped high frequency voltage to the upper electrode. The processing gas includes a gas used in forming a film and providing a raw material of the film to the substrate.

[0022] Since the voltage waveform is shaped by full-wave rectification that converts positive voltage components into negative voltage components, the peak of the negative voltage component of the shaped voltage applied to the upper electrode is similar to the peak of the negative voltage component of the unshaped voltage (e.g., a sinusoidal voltage output by a high-frequency power supply). This makes it possible to reduce the sheath voltage on the lower electrode while suppressing an increase in the sheath voltage on the upper electrode. This makes it possible to suppress an increase in the energy of ions bombarding the upper electrode and reduce the energy of ions incident on the lower electrode.

[0023] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0024] Fig. 1 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 100 shown in Fig. 1 performs plasma processing on a substrate W. The plasma processing apparatus 100 may be a capacitively coupled plasma processing apparatus. The substrate W may be, for example, a semiconductor wafer, but is not limited thereto.

[0025] The plasma processing apparatus 100 has a substantially cylindrical metal processing vessel 1. The processing vessel 1 is electrically grounded. A substrate mounting table 2 for horizontally mounting a substrate W thereon is provided inside the processing vessel 1. The substrate mounting table 2 includes an electrically grounded lower electrode. This lower electrode is provided inside the processing vessel 1. The substrate mounting table 2 illustrated in FIG. 1 is an electrically grounded conductor and serves as the lower electrode.

[0026] The substrate mounting table 2 may have a heating mechanism or a cooling mechanism depending on the plasma processing. A plurality of lift pins (not shown) are inserted into the substrate mounting table 2 so as to be capable of protruding and retracting from the upper surface of the substrate mounting table 2. The substrate W is transferred to and from the substrate mounting table 2 by the lifting mechanism (not shown) lifting and lowering the plurality of lift pins.

[0027] An opening is provided at the top of the processing vessel 1, and a shower head 10 is fitted into the opening via an insulating member 9 so as to face a substrate mounting table 2 (hereinafter simply referred to as the substrate mounting table 2) which is a lower electrode. The shower head 10 is a conductor. The shower head 10 may be an upper electrode to which a high frequency voltage is applied from a high frequency power supply 30. The shower head 10 (hereinafter simply referred to as the shower head 10) which is the upper electrode may have an overall shape of a cylinder. The shower head 10 has a main body 11 having an opening at the bottom, and a shower plate 12 provided to close the opening of the main body 11. The internal space between the main body 11 and the shower plate 12 provides a gas diffusion space. The shower plate 12 is provided with a plurality of gas ejection holes 13.

[0028] The shower head 10 is provided with a gas inlet 14, and a processing gas for plasma processing supplied from a gas supply unit 20 is introduced into the shower head 10 through the gas inlet 14.

[0029] The gas supply unit 20 is configured to supply a processing gas between the shower head 10 and the substrate mounting table 2. The processing gas introduced into the shower head 10 is introduced into the processing vessel 1 through the gas outlet holes 13 and supplied to the space between the shower head 10 and the substrate mounting table 2.

[0030] The gas supply unit 20 supplies a plurality of gases, such as a processing gas, a plasma generating gas, and a purge gas, required for the plasma processing. An appropriate processing gas is selected depending on the plasma processing to be performed. For example, the processing gas may include a gas used in forming a film and providing a raw material of the film to the substrate W. The gas supply unit 20 has a plurality of gas supply sources and gas supply piping, and the gas supply piping is provided with a flow rate controller such as a valve and a mass flow controller.

[0031] A high frequency power supply 30 is electrically connected to the showerhead 10. The high frequency power supply 30 is configured to output a high frequency voltage of 10 kHz to 60 MHz. When the high frequency voltage is applied from the high frequency power supply 30 to the showerhead 10, a capacitively coupled plasma is generated between the showerhead 10 and the substrate mounting table 2.

[0032] The matching box 32 is electrically connected between the high frequency power supply 30 and the voltage waveform shaping unit 33. The matching box 32 is electrically connected to the high frequency power supply 30 and the voltage waveform shaping unit 33. The matching box 32 is configured to match a load impedance to an internal impedance (or an output impedance) of the high frequency power supply 30.

[0033] The voltage waveform shaping unit 33 is electrically connected between the matching unit 32 and the shower head 10. The voltage waveform shaping unit 33 is electrically connected to the matching unit 32 and the shower head 10. The voltage waveform shaping unit 33 is a full-wave rectifier configured to shape the voltage waveform of the high frequency voltage output from the high frequency power supply 30 by converting a positive voltage component into a negative voltage component.

[0034] An example of the configuration of the voltage waveform shaping section 33 is shown in Fig. 2. Other examples of the configuration of the voltage waveform shaping section 33 are shown in each of Figs. 6 to 9.

[0035] As illustrated in FIG. 2, the voltage waveform shaping unit 33 includes a transformer TR1, a rectifier RF1, and a rectifier RF2. The transformer TR1 includes a primary coil and a secondary coil. The primary coil includes a coil TRa. The secondary coil includes a coil TRb and a coil TRc. The high frequency power supply 30 is electrically connected between two terminals of the coil TRa. The two coils (coil TRb, coil TRc) of the secondary coil are connected in series. The two terminals of the secondary coil are electrically connected to the cathode of the rectifier RF1 and the cathode of the rectifier RF2, respectively. In other words, the coil TRb included in the secondary coil is electrically connected to the cathode of the rectifier RF1, and the coil TRc included in the secondary coil is electrically connected to the cathode of the rectifier RF2. The connection point of the coil TRb and the coil TRc is electrically grounded. The anode of the rectifier RF1 and the anode of the rectifier RF2 are electrically connected to the shower head 10.

[0036] 2 is used, the high frequency voltage output from the high frequency power supply 30 is full-wave rectified by the voltage waveform shaping unit 33 while plasma is being generated. The current flowing between the substrate mounting table 2 and the shower head 10 becomes a direct current flowing only through the discharge path in the direction AL1 from the substrate mounting table 2 toward the shower head 10. The direction AL1 indicates the direction from the substrate mounting table 2 toward the shower head 10. The same applies when the voltage waveform shaping units 33 illustrated in each of FIGS. 6, 7, and 8 are used.

[0037] Returning to Fig. 1, an exhaust port 41 is provided in the bottom wall of the processing vessel 1, and an exhaust device 43 is connected to the exhaust port 41 via an exhaust pipe 42. The exhaust device 43 has an automatic pressure control valve and a vacuum pump. The exhaust device 43 evacuates the processing vessel 1 and can maintain the inside of the processing vessel 1 at a preset vacuum level.

[0038] Although not shown, a loading / unloading port is provided on a side wall of the processing vessel 1 for loading / unloading the substrate W into / from the processing vessel 1. This loading / unloading port is configured to be opened and closed by a gate valve.

[0039] The valves and flow rate controllers of the gas supply unit 20, as well as the high-frequency power source and the like, are controlled by a control unit 50. The control unit 50 has a main control unit having a CPU, an input device, an output device, a display device, and a storage device. Various processes performed by the plasma processing device 100 are controlled based on processing recipes stored in a storage medium of the storage device. In particular, the control unit 50 controls each component of the plasma processing device 100 to execute each step of a processing method MT illustrated in FIG.

[0040] 10, a processing method MT for performing plasma processing on a substrate W placed inside a processing vessel 1 of a plasma processing apparatus 100 will be described. First, a gate valve is opened, and a transfer device (not shown) transfers the substrate W into the processing vessel 1 through a transfer port, and places the substrate W on a substrate mounting table 2 to prepare the substrate W (step ST1). After the transfer device is retracted, the gate valve is closed.

[0041] In step ST2 performed following step ST1, after adjusting the pressure in the processing chamber 1, a processing gas is supplied between an upper electrode (e.g., the shower head 10) and a lower electrode (e.g., the substrate mounting table 2) of the plasma processing apparatus 100 (step ST2).

[0042] Step ST3 is performed following step ST2 or together with step ST2. In step ST3, the voltage waveform of the high frequency voltage output from the high frequency power supply 30 is shaped by converting a positive voltage component into a negative voltage component (step ST3).

[0043] In step ST4 which is performed following step 3, the shaped high frequency voltage is applied to the upper electrode.

[0044] Therefore, a high-frequency electric field is formed between the shower head 10 and the substrate mounting table 2, generating a capacitively coupled plasma.

[0045] In a typical capacitively coupled plasma processing apparatus, when the lower electrode is electrically grounded, the plasma potential is highly dependent on the potential of the upper electrode. At the moment when the upper electrode is at 0V, the plasma potential is αV, but at the moment when the upper electrode is at 100V, the plasma potential can be about 100+αV. Ions in the plasma are accelerated by the sheath voltage (the difference between the plasma potential and the substrate potential) on the surface of the substrate and flow into the substrate. In order to increase the power input to the plasma, it is conceivable to increase the amplitude of the sinusoidal high-frequency voltage output by the high-frequency power supply. In this case, the plasma potential is raised by the positive part of the high-frequency voltage output by the high-frequency power supply, and the sheath voltage becomes high. As a result, the acceleration of ions toward the substrate W increases, and the ion bombardment on the substrate W can become stronger.

[0046] In contrast, the plasma processing apparatus 100 described above is provided with a voltage waveform shaping unit 33 downstream of the matching unit 32. The voltage waveform shaping unit 33 performs full-wave rectification to shape the voltage waveform of the high frequency voltage output from the high frequency power supply 30 by converting a positive voltage component into a negative voltage component. The full-wave rectification by the voltage waveform shaping unit 33 changes the positive voltage component in the high frequency voltage applied to the shower head 10 to a negative voltage component. In this case, the peak of the negative voltage component of the shaped voltage applied to the shower head 10 is similar to the peak of the negative voltage component of the voltage (e.g., a sine wave voltage output from the high frequency power supply 30) that has not been shaped. Therefore, in particular, an increase in the energy with which ions in the plasma impact the shower head 10 is suppressed, and the energy with which ions in the plasma impact the substrate mounting table 2 and the substrate W is reduced.

[0047] The effect of full-wave rectification of the high frequency voltage applied to the shower head 10 will be described with reference to Figures 3, 4, and 5. The following description is the same for the configurations shown in Figures 2, and 6 to 9.

[0048] The horizontal axis in each of Figures 3, 4, and 5 represents time (us). The vertical axis in Figure 3 represents the voltage (V) applied to the showerhead 10. The vertical axis in Figure 4 represents the first sheath voltage (V) formed on the surface of the showerhead 10. The vertical axis in Figure 5 represents the second sheath voltage (V) formed on the surface of the substrate W. The results shown in Figures 3 to 5 were obtained by simulation.

[0049] Waveforms A1, A2, and A3 represent voltage waveforms when a sine-wave high-frequency voltage output from the high-frequency power supply 30 without full-wave rectification is applied to the shower head 10. Waveforms B1, B2, and B3 represent voltage waveforms of the high-frequency voltage after the sine-wave high-frequency voltage output from the high-frequency power supply 30 has been full-wave rectified by the voltage waveform shaping unit 33. Waveforms C1, C2, and C3 represent voltage waveforms of the high-frequency voltage after the sine-wave high-frequency voltage output from the high-frequency power supply 30 has been half-wave rectified.

[0050] Referring to Figure 3, it can be seen that the peak of the negative voltage component of the high frequency voltage after shaping by full-wave rectification (waveform B1) is similar to the peak of the negative voltage component of the sine wave high frequency voltage (waveform A1). On the other hand, it can be seen that the peak of the negative voltage component of the high frequency voltage after shaping by full-wave rectification (waveform B1) is reduced more than the peak of the negative voltage component of the high frequency voltage after shaping by half-wave rectification (waveform C1).

[0051] 4, it can be seen that the peak of the first sheath voltage (waveform B2) when the radio frequency voltage of waveform B1 after shaping by full-wave rectification is applied to the shower head 10 is similar to the first sheath voltage (waveform A2) when the radio frequency voltage of waveform A1 is applied to the shower head 10. On the other hand, it can be seen that the peak of the first sheath voltage of waveform B2 is lower than the peak of the first sheath voltage (waveform C2) when the radio frequency voltage after shaping by half-wave rectification (waveform C1) is applied to the shower head 10.

[0052] 5, it can be seen that the peak of the second sheath voltage (waveform B3) when the radio frequency voltage of waveform B1 after shaping by full-wave rectification is applied to the shower head 10 is lower than the second sheath voltage (waveform A3) when the radio frequency voltage of waveform A1 is applied to the shower head 10. On the other hand, it can be seen that the peak of the second sheath voltage of waveform B3 is lower than the peak of the second sheath voltage (waveform C3) when the radio frequency voltage after shaping by half-wave rectification (waveform C1) is applied to the shower head 10.

[0053] In this way, the sine wave high frequency voltage output from the high frequency power supply 30 is full-wave rectified by the voltage waveform shaping unit 33, and the resulting high frequency voltage is applied to the shower head 10. This makes it possible to suppress an increase in the sheath voltage on the upper electrode (specifically, on the surface of the substrate W) while reducing the sheath voltage on the lower electrode (specifically, on the surface of the shower head 10). This makes it possible to suppress an increase in the energy of ions impacting the upper electrode (shower head 10) and reduce the energy of ions incident on the lower electrode (substrate mounting table 2 and substrate W). The above description is the same when not only the voltage waveform shaping unit 33 in FIG. 2 but also each of the voltage waveform shaping units 33 in FIG. 6 to FIG. 8 is used, and also when the substrate mounting table 2 and ground electrode 2b in FIG. 9 are used.

[0054] Fig. 6 shows another example of the configuration of the voltage waveform shaping unit 33. The voltage waveform shaping unit 33 shown in Fig. 6 includes a transformer TR2 and a diode bridge circuit DB. The transformer TR2 includes a primary coil and a secondary coil.

[0055] The primary coil includes a coil TRd. A high frequency power supply 30 is electrically connected between two terminals of the coil TRd. The secondary coil includes a coil TRe. A diode bridge circuit DB is electrically connected between two terminals of the coil TRe.

[0056] The diode bridge circuit DB includes a rectifier DOa, a rectifier DOb, a rectifier DOc, and a rectifier DOd. The cathode of the rectifier DOa is electrically connected to the anode of the rectifier DOb. The anode of the rectifier DOa is electrically connected to the anode of the rectifier DOc. The cathode of the rectifier DOb is electrically connected to the cathode of the rectifier DOd. The cathode of the rectifier DOc is electrically connected to the anode of the rectifier DOd.

[0057] The cathode of the rectifier DOa and the anode of the rectifier DOb are electrically connected to the cathode of the rectifier DOc and the anode of the rectifier DOd via the coil TRe. The anode of the rectifier DOa and the anode of the rectifier DOc are electrically connected to the showerhead 10. The cathode of the rectifier DOb and the cathode of the rectifier DOd are electrically grounded.

[0058] FIG. 7 shows another example of the configuration of the voltage waveform shaping unit 33. The voltage waveform shaping unit 33 shown in FIG. 7 has a diode bridge circuit DB. The diode bridge circuit DB has a rectifier DOa, a rectifier DOb, a rectifier DOc, and a rectifier DOd. The cathode of the rectifier DOa is electrically connected to the anode of the rectifier DOb. The anode of the rectifier DOa is electrically connected to the anode of the rectifier DOc. The cathode of the rectifier DOb is electrically connected to the cathode of the rectifier DOd. The cathode of the rectifier DOc is electrically connected to the anode of the rectifier DOd. Each of the two terminals of the high frequency power supply 30 is electrically connected to the cathode of the rectifier DOa and the cathode of the rectifier DOc. In other words, each of the two terminals of the high frequency power supply 30 is electrically connected to the anode of the rectifier DOb and the anode of the rectifier DOd. The anode of the rectifier DOa and the anode of the rectifier DOc are electrically connected to the showerhead 10. The cathode of the rectifier DOb and the cathode of the rectifier DOd are electrically grounded to the substrate mounting table 2.

[0059] FIG. 8 shows another example of the configuration of the voltage waveform shaping unit 33. The voltage waveform shaping unit 33 shown in FIG. 8 includes a transformer TR1, a switching element SW1, and a switching element SW2. The transformer TR1 includes a primary coil and a secondary coil. The primary coil includes a coil TRa. The secondary coil includes a coil TRb and a coil TRc. The high-frequency power source 30 is electrically connected between the two terminals of the coil TRa. The two coils (coil TRb and coil TRc) of the secondary coil are connected in series. The two terminals of the secondary coil are electrically connected to the switching element SW1 and the switching element SW2, respectively. In other words, the coil TRb included in the secondary coil is electrically connected to the switching element SW1, and the coil TRc included in the secondary coil is electrically connected to the switching element SW2. The connection point of the coil TRb and the coil TRc is electrically grounded. The switching element SW1 and the switching element SW2 are electrically connected to the shower head 10. Two terminals of the secondary coil are electrically connected to the showerhead 10 via switching element SW1 and switching element SW2, respectively.

[0060] The switching element SW1 and the switching element SW2 may be field effect transistors (FETs), etc. The switching element SW1 and the switching element SW2 are configured to cut off the current flowing from the secondary coil.

[0061] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various omissions, substitutions, and modifications may be made. In addition, elements in different exemplary embodiments may be combined to form other exemplary embodiments.

[0062] For example, the substrate mounting table may have a material other than a conductor. The material of the substrate mounting table 2 shown in FIG. 9 may be an insulator such as ceramic, for example, AlN. The substrate mounting table 2 includes an electrostatic chuck 2a that is electrically grounded. A ground electrode 2b is provided on the outside of the substrate mounting table 2. The ground electrode 2b is electrically grounded. The ground electrode 2b may be arranged, for example, so as to surround the substrate mounting table 2. When the high-frequency voltage output from the high-frequency power supply 30 is full-wave rectified by the voltage waveform shaping unit 33 while plasma is being generated, the current becomes a direct current that flows only in the discharge path in the direction AL1 (FIG. 2, etc.) from the substrate mounting table 2 toward the shower head 10. For this reason, when an insulator is present in the discharge path in the direction AL1, no direct current flows in the discharge path in the direction AL1. On the other hand, when the ground electrode 2b is provided on the outside of the substrate mounting table 2 made of an insulator, a new discharge path in the direction AL2 that avoids the substrate mounting table 2 may be formed. The direction AL2 indicates the direction from the ground electrode 2b toward the shower head 10. Therefore, even if the substrate mounting table 2 is made of an insulator, a direct current can be caused to flow in the direction AL2 from the ground electrode 2b toward the shower head 10 while plasma is being generated.

[0063] From the foregoing, it will be understood that various exemplary embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various exemplary embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0064] 100...plasma processing apparatus, 10...shower head, 1...processing vessel, 2...substrate mounting stage, 2b...ground electrode, 30...high frequency power supply, 32...matching box, 33...voltage waveform shaping section, DB...diode bridge circuit, DOa...rectifier, DOb...rectifier, DOc...rectifier, DOd...rectifier, RF1...rectifier, RF2...rectifier, MT...processing method, SW1...switching element, SW2...switching element, TR1...transformer, TR2...transformer, TRa...coil, TRb...coil, TRc...coil, TRd...coil, TRd...coil.

Claims

1. A processing vessel; a lower electrode provided inside the processing vessel; an upper electrode disposed opposite the lower electrode; a gas supply configured to supply a process gas between the upper electrode and the lower electrode; A high frequency power supply configured to output a high frequency voltage; a voltage waveform shaping unit provided between the high frequency power supply and the upper electrode, configured to shape a voltage waveform of the high frequency voltage output from the high frequency power supply by converting a positive voltage component into a negative voltage component; Equipped with a high frequency voltage having a voltage waveform obtained by converting the positive voltage component of the high frequency voltage output from the high frequency power supply into the negative voltage component by the voltage waveform shaping unit is applied to the upper electrode; The lower electrode is a substrate support on which a substrate is placed and is an electrically grounded conductor. Plasma processing equipment.

2. a shower head for introducing the processing gas into the processing chamber; The showerhead is the upper electrode. The plasma processing apparatus according to claim 1 .

3. The power supply may further include a matching box electrically connected between the high frequency power supply and the voltage waveform shaping unit.

3. The plasma processing apparatus according to claim 1 or 2.

4. The process gas includes a gas used to form a film and providing a precursor of the film to a substrate disposed in the process chamber. The plasma processing apparatus according to any one of claims 1 to 3.

5. the voltage waveform shaping unit includes a transformer, a first rectifier, and a second rectifier; The transformer has a primary coil and a secondary coil, The high frequency power source is electrically connected between two terminals of the primary coil, The secondary coil has two coils connected in series, Two terminals of the secondary coil are electrically connected to the cathode of the first rectifier and the cathode of the second rectifier, respectively; The connection point of the two coils of the secondary coil is electrically grounded; the anode of the first rectifier and the anode of the second rectifier are electrically connected to the upper electrode; The plasma processing apparatus according to any one of claims 1 to 4.

6. the voltage waveform shaping unit includes a transformer and a diode bridge circuit, The transformer has a primary coil and a secondary coil, The high frequency power source is electrically connected between two terminals of the primary coil, the diode bridge circuit includes a first rectifier, a second rectifier, a third rectifier, and a fourth rectifier; the cathode of the first rectifier is electrically connected to the anode of the second rectifier; an anode of the first rectifier electrically connected to an anode of the third rectifier; the cathode of the second rectifier is electrically connected to the cathode of the fourth rectifier; the cathode of the third rectifier is electrically connected to the anode of the fourth rectifier; the cathode of the first rectifier is electrically connected to the cathode of the third rectifier via the secondary coil; the anode of the first rectifier and the anode of the third rectifier are electrically connected to the upper electrode; the cathode of the second rectifier and the cathode of the fourth rectifier are electrically grounded; The plasma processing apparatus according to any one of claims 1 to 4.

7. the voltage waveform shaping unit has a diode bridge circuit, the diode bridge circuit includes a first rectifier, a second rectifier, a third rectifier, and a fourth rectifier; the cathode of the first rectifier is electrically connected to the anode of the second rectifier; an anode of the first rectifier electrically connected to an anode of the third rectifier; the cathode of the second rectifier is electrically connected to the cathode of the fourth rectifier; the cathode of the third rectifier is electrically connected to the anode of the fourth rectifier; Two terminals of the high frequency power supply are electrically connected to the cathode of the first rectifier and the cathode of the third rectifier, respectively; the anode of the first rectifier and the anode of the third rectifier are electrically connected to the upper electrode; the cathode of the second rectifier and the cathode of the fourth rectifier are electrically connected to the lower electrode; The plasma processing apparatus according to any one of claims 1 to 4.

8. the voltage waveform shaping unit includes a transformer, a first switching element, and a second switching element; The transformer has a primary coil and a secondary coil, The high frequency power source is electrically connected between two terminals of the primary coil, The secondary coil has two coils connected in series, two terminals of the secondary coil are electrically connected to the first switching element and the second switching element, respectively; The connection point of the two coils of the secondary coil is electrically grounded; two terminals of the secondary coil are electrically connected to the upper electrode via the first switching element and the second switching element, respectively; The first switching element and the second switching element are configured to interrupt a current flowing from the secondary coil. The plasma processing apparatus according to any one of claims 1 to 4.

9. 1. A method for performing plasma processing on a substrate placed inside a processing vessel of a plasma processing apparatus, comprising: supplying a processing gas between an upper electrode and a lower electrode of the plasma processing apparatus; a step of converting a positive voltage component into a negative voltage component to thereby shape a voltage waveform of a high frequency voltage output from a high frequency power supply of the plasma processing apparatus; applying the shaped high frequency voltage to the upper electrode; having In the step of applying a high frequency voltage to the upper electrode, a high frequency voltage having a voltage waveform in which the positive voltage component of the high frequency voltage output from the high frequency power supply is converted into the negative voltage component is applied to the upper electrode; the lower electrode is a substrate support on which a substrate is placed and is an electrically grounded conductor; The process gas includes a gas used to form a film and provides a raw material for the film to the substrate. Processing methods.

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