Plasma processing apparatus and plasma processing method

Abstract

The present application provides a plasma processing apparatus and a plasma processing method. The plasma processing apparatus includes a processing container, a gas supply portion, an electric power supply portion, and a control device. The processing container accommodates a substrate. The gas supply portion supplies a processing gas into the processing container. The electric power supply portion generates a plasma from the processing gas supplied into the processing container by supplying electric power into the processing container, and processes the substrate with the generated plasma. The control device controls the electric power supply portion. Also, the control device performs the following steps: step a, when generating the plasma from the processing gas, controls the electric power supply portion to supply electric power containing a frequency component included in a frequency band of a first bandwidth into the processing container; and step b, when processing the substrate with the generated plasma, controls the electric power supply portion to supply electric power containing a frequency component included in a frequency band of a second bandwidth lower than the first bandwidth into the processing container. According to the present application, the plasma can be generated more reliably and maintained stably.

Description

Technical Field

[0001] Various aspects and embodiments of the present invention relate to plasma processing apparatus and plasma processing methods. Background Technology

[0002] In the manufacturing process of devices, there is a step involving plasma treatment. In plasma treatment, plasma is generated from the processing gas supplied to the processing container by supplying electrical power at a predetermined frequency into the processing container. The generated plasma is then used to perform plasma treatments such as etching on the substrate.

[0003] However, the resonance conditions within the processing container differ depending on whether plasma is present or absent. Therefore, when selecting the frequency of the electrical power supplied to the processing container based on the resonance conditions under the normal state where plasma is present, there are cases where plasma cannot be generated within the processing container.

[0004] To avoid this, there is a known technique that shifts the frequency of the electrical power supplied to the processing container during plasma generation to a relatively higher frequency than the normal frequency for plasma excitation (for example, see Patent Document 1 below).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 3122618. Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The present invention provides a plasma processing apparatus and a plasma processing method that can generate plasma more reliably and maintain plasma stably.

[0010] Technical means for solving problems

[0011] One aspect of the present invention is a plasma processing apparatus, comprising a processing container, a gas supply unit, an electrical power supply unit, and a control device. The processing container houses a substrate. The gas supply unit supplies processing gas into the processing container. The electrical power supply unit generates plasma from the processing gas supplied into the processing container by supplying electrical power into the processing container, and uses the generated plasma to process the substrate. The control device controls the electrical power supply unit. Furthermore, the control device performs the following steps: step a, when generating plasma from the processing gas, controlling the electrical power supply unit to supply electrical power into the processing container containing frequency components contained in a frequency band of a first bandwidth; step b, when processing the substrate with the generated plasma, controlling the electrical power supply unit to supply electrical power into the processing container containing frequency components contained in a frequency band of a second bandwidth less than the first bandwidth.

[0012] The effects of the invention

[0013] According to various aspects and embodiments of the present invention, plasma can be generated more reliably and maintained stably. Attached Figure Description

[0014] Figure 1 This is a schematic cross-sectional view illustrating an example of a plasma processing apparatus according to one embodiment of the present invention.

[0015] Figure 2 This is a block diagram representing an example of a microwave output device.

[0016] Figure 3 This is a block diagram illustrating the details of the waveform generation section.

[0017] Figure 4 This is a diagram illustrating an example of the frequency distribution of the electric power of the reflected wave before plasma generation.

[0018] Figure 5 This is a diagram illustrating an example of the frequency distribution of the electric power of the reflected wave after plasma generation.

[0019] Figure 6 This is a flowchart illustrating an example of the plasma processing method according to the first embodiment.

[0020] Figure 7A This is a diagram illustrating an example of microwaves supplied before plasma generation.

[0021] Figure 7B This is a diagram illustrating an example of microwaves supplied during plasma processing in the first embodiment.

[0022] Figure 8 This is a flowchart illustrating an example of the plasma processing method according to the second embodiment.

[0023] Figure 9 This is a diagram illustrating an example of microwaves supplied during plasma processing in the second embodiment.

[0024] Figure 10 This is a flowchart illustrating an example of the plasma processing method according to the third embodiment.

[0025] Figure 11A This is a diagram illustrating an example of microwaves supplied before plasma generation.

[0026] Figure 11B This is a diagram illustrating an example of microwaves supplied during the period from plasma generation to the start of plasma processing.

[0027] Figure 11C This is a diagram illustrating an example of microwaves supplied during plasma processing.

[0028] Figure 12 This is a flowchart illustrating an example of the plasma processing method according to the fourth embodiment.

[0029] Figure 13 This is a diagram illustrating an example of a method for determining the bandwidth and center frequency of microwaves before plasma generation.

[0030] Figure 14 This is a diagram illustrating another example of how the bandwidth and center frequency of microwaves are determined before plasma generation.

[0031] Explanation of reference numerals in the attached figures

[0032] W1 bandwidth

[0033] W2 bandwidth

[0034] W3 bandwidth

[0035] WP substrate

[0036] 1. Plasma processing device

[0037] 11 Control device

[0038] 12. Handling Containers

[0039] 14 Processing Table

[0040] 16 Microwave output device

[0041] 18 antennas

[0042] 20 Dielectric Window

[0043] 38 Gas Supply Department Detailed Implementation

[0044] Hereinafter, embodiments of the disclosed plasma processing apparatus and plasma processing method will be described in detail based on the accompanying drawings. However, the disclosed plasma processing apparatus and plasma processing method are not limited to the following embodiments.

[0045] However, the resonance conditions within the processing container are affected by a variety of factors, including the shape, size, and location of the components, the type of processing gas, and the pressure within the container. Furthermore, the shape and location of the components include dimensional and installation errors. Additionally, with numerous plasma treatments performed within the container, the amount of deposits adhering to the components and the consumption of components can vary. Therefore, the resonance conditions within the processing container vary depending on the environment within the container.

[0046] Therefore, even if the frequency of the electrical power corresponding to the resonance condition is determined based on design values, there is a possibility that the determined frequency of the resonance condition may deviate from the actual frequency of the resonance condition in the process. When the frequency of the electrical power supplied to the processing container differs from the frequency of the resonance condition, sufficient electrical power will not be supplied to the processing container, making it difficult to generate plasma. Therefore, it is considered to supply electrical power containing a frequency component with a bandwidth that includes the frequency of the actual resonance condition in the process.

[0047] Here, once plasma is generated, impedance matching is continuously performed between the output impedance of the power supply device and the load impedance containing the processing container and the plasma in order to maintain the generated plasma. At this time, if the bandwidth of the power supplied to the processing container is wide or the center frequency in the same bandwidth is deviated, the reflected waves will increase due to the deviation of the impedance matching point at the moment when plasma generation begins, making it difficult to perform impedance matching with high precision.

[0048] Therefore, the present invention provides a technique that can generate plasma more reliably and maintain plasma stably.

[0049] (First Implementation)

[0050] [Structure of Plasma Processing Unit 1]

[0051] Figure 1 This is a schematic cross-sectional view illustrating an example of a plasma processing apparatus 1 according to one embodiment of the present invention. The plasma processing apparatus 1 includes an apparatus body 10 and a control device 11. The apparatus body 10 includes a processing container 12 and a microwave output device 16.

[0052] The processing container 12 is formed into a generally cylindrical shape, for example, from aluminum with an anodized surface, and provides a generally cylindrical processing space S inside. The processing container 12 is safely grounded. Furthermore, the processing container 12 has a side wall 12a and a bottom 12b. The central axis of the side wall 12a is defined as axis Z. The bottom 12b is located at the lower end of the side wall 12a. An exhaust port 12h for venting is formed in the bottom 12b. Additionally, the upper end of the side wall 12a is open.

[0053] An opening 12c for feeding and feeding the substrate WP is formed in the side wall 12a. The opening 12c is opened and closed by a gate G.

[0054] A dielectric window 20 is provided at the upper end of the side wall 12a, which closes the opening at the upper end of the side wall 12a from above. The lower surface of the dielectric window 20 faces the processing space S. A sealing component 19, such as an O-ring, is disposed between the dielectric window 20 and the upper end of the side wall 12a.

[0055] A processing stage 14 is provided inside the processing container 12. The processing stage 14 is arranged facing the dielectric window 20 in the direction of axis Z. The space between the processing stage 14 and the dielectric window 20 is the processing space S. A substrate WP is placed on the processing stage 14.

[0056] The processing table 14 has a base 14a and an electrostatic chuck 14c. The base 14a is formed of a generally disc-shaped material such as aluminum, which is conductive. The base 14a is arranged in the processing container 12 such that the central axis of the base 14a is approximately aligned with the axis Z.

[0057] The base 14a is formed of an insulating material and is supported by a cylindrical support 48 extending along the Z-axis. A conductive cylindrical support 50 is provided on the outer periphery of the cylindrical support 48. The cylindrical support 50 extends along the outer periphery of the cylindrical support 48 from the bottom 12b of the processing container 12 toward the dielectric window 20. An annular venting path 51 is formed between the cylindrical support 50 and the sidewall 12a.

[0058] An annular baffle 52 with multiple through holes formed in the thickness direction is provided at the upper part of the exhaust path 51. An exhaust port 12h is provided below the baffle 52. An exhaust device 56, which includes a vacuum pump such as a turbomolecular pump or an automatic pressure control valve, is connected to the exhaust port 12h via an exhaust pipe 54. The exhaust device 56 can reduce the pressure of the processing space S to a preset vacuum level.

[0059] The base station 14a functions as an RF (Radio Frequency) electrode. An RF power supply 58 for RF bias is electrically connected to the base station 14a via a power supply bar 62 and a matching unit 60. The RF power supply 58 supplies bias power at a frequency (e.g., 13.56 MHz) suitable for controlling the energy of ions attracted to the substrate WP via the matching unit 60 and the power supply bar 62 to the base station 14a.

[0060] Matching unit 60 houses a matching unit for matching the impedance on the RF power supply 58 side with the impedance on the load side, primarily the electrodes, plasma, and processing container 12. The matching unit includes a DC blocking capacitor for self-bias generation.

[0061] An electrostatic chuck 14c is provided on the upper surface of the substrate 14a. The electrostatic chuck 14c is arranged on the upper surface of the substrate 14a such that its central axis is approximately aligned with axis Z. The electrostatic chuck 14c uses electrostatic force to attract and hold the substrate WP. The electrostatic chuck 14c has a generally disc-shaped shape and includes an electrode 14d, an insulating film 14e, and an insulating film 14f. The electrode 14d of the electrostatic chuck 14c is made of a conductive film and is disposed between the insulating films 14e and 14f. The electrode 14d is electrically connected to a DC power supply 64 via a covering wire 68 and a switch 66. The electrostatic chuck 14c can attract and hold the substrate WP on its upper surface by the electrostatic force generated by the DC voltage applied from the DC power supply 64. In addition, an edge ring 14b is provided on the substrate 14a. The edge ring 14b is arranged to surround the substrate WP and the electrostatic chuck 14c. The edge ring 14b is sometimes also referred to as a focusing ring.

[0062] A flow path 14g is formed inside the base 14a. A refrigeration unit (not shown) supplies refrigerant to the flow path 14g via piping 70. The refrigerant supplied to the flow path 14g returns to the refrigeration unit via piping 72. The refrigerant, whose temperature is controlled by the refrigeration unit, circulates within the flow path 14g of the base 14a, thereby controlling the temperature of the base 14a. By controlling the temperature of the base 14a, the temperature of the substrate WP on the electrostatic chuck 14c can be controlled via the electrostatic chuck 14c on the base 14a.

[0063] In addition, the processing table 14 is provided with a piping 74 for supplying heat transfer gases such as He gas between the electrostatic chuck 14c and the substrate WP.

[0064] The microwave output device 16 outputs microwaves to excite the processing gas supplied to the processing container 12. The microwave output device 16 is an example of an electrical power supply unit. The microwave output device 16 is capable of adjusting the microwave bandwidth, center frequency, and electrical power. For example, the microwave output device 16 can adjust the microwave bandwidth and center frequency within a frequency range of 2.4 GHz to 2.5 GHz.

[0065] In addition, the main body 10 of the device also includes a waveguide 21, a tuner 26, a mode converter 27, and a coaxial waveguide 28. The output section of the microwave output device 16 is connected to one end of the waveguide 21. The other end of the waveguide 21 is connected to the mode converter 27. The waveguide 21 is, for example, a rectangular waveguide. A tuner 26 is provided in the waveguide 21. The tuner 26 has a movable plate 26a and a movable plate 26b. By adjusting the protrusion of the movable plates 26a and 26b relative to the internal space of the waveguide 21, the output impedance of the microwave output device 16 can be matched with the impedance of the load.

[0066] The mode converter 27 converts the mode of the microwave output from the waveguide 21 and supplies the mode-converted microwave to the coaxial waveguide 28. The coaxial waveguide 28 transmits the mode-converted microwave to the antenna 18. The coaxial waveguide 28 includes an outer conductor 28a and an inner conductor 28b. The outer conductor 28a and the inner conductor 28b have a generally cylindrical shape. The outer conductor 28a and the inner conductor 28b are arranged on the upper part of the antenna 18 such that their central axes are approximately aligned with axis Z.

[0067] Antenna 18 supplies microwaves to the processing container 12. Antenna 18 is disposed on the upper surface of dielectric window 20. Antenna 18 includes slot plate 30, dielectric plate 32, and cooling housing 34. Slot plate 30 is formed of conductive metal in a generally circular plate shape. Slot plate 30 is disposed on the upper surface of dielectric window 20 with its central axis aligned with axis Z. Multiple slots are formed in slot plate 30. The multiple slots constitute, for example, multiple pairs of slots. Each pair of slots includes two slots in the shape of elongated holes extending in mutually intersecting directions. The multiple pairs of slots are arranged in more than one concentric circle around the central axis of slot plate 30. In addition, a through hole 30d is formed in the central part of slot plate 30 through which the conduit 36 ​​described later can pass.

[0068] The dielectric plate 32 is formed into a roughly disk-shaped form from a dielectric material such as quartz. The dielectric plate 32 is mounted on the slot plate 30 with its central axis approximately aligned with axis Z. A cooling housing 34 is mounted on the dielectric plate 32. The dielectric plate 32 is positioned between the cooling housing 34 and the slot plate 30.

[0069] The surface of the cooling housing 34 is conductive. A flow path 34a is formed inside the cooling housing 34. A refrigeration unit (not shown) supplies refrigerant to the flow path 34a. The upper surface of the cooling housing 34 is electrically connected to the lower end of the outer conductor 28a. Furthermore, the lower end of the inner conductor 28b is electrically connected to the slot plate 30 through an opening formed in the central portion of the cooling housing 34 and the dielectric plate 32.

[0070] Microwaves transmitted within the coaxial waveguide 28 are transmitted to the dielectric plate 32 and then through multiple slots in the slotted plate 30 to the dielectric window 20. The microwaves transmitted to the dielectric window 20 radiate from the lower surface of the dielectric window 20 into the processing space S.

[0071] A conduit 36 ​​is disposed inside the inner conductor 28b of the coaxial waveguide 28. A through hole 30d is formed in the center of the slot plate 30 for the conduit 36 ​​to pass through. The conduit 36 ​​passes through the inner conductor 28b and extends to connect with the gas supply section 38.

[0072] The gas supply unit 38 supplies processing gas for processing the substrate WP to the conduit 36. The gas supply unit 38 includes a gas supply source 38a, a valve 38b, and a flow controller 38c. The gas supply source 38a is the source of the processing gas. The valve 38b controls the supply and stop of the processing gas from the gas supply source 38a. The flow controller 38c, such as a mass flow controller, controls the flow rate of the processing gas supplied from the gas supply source 38a to the conduit 36.

[0073] An injector 41 is provided in the dielectric window 20. The injector 41 supplies gas from the conduit 36 ​​into the through hole 20h formed in the dielectric window 20. The gas supplied to the through hole 20h of the dielectric window 20 is injected into the processing space S and excited by microwaves radiated from the dielectric window 20 into the processing space S. As a result, the processing gas in the processing space S is plasmaified, and the substrate WP on the electrostatic chuck 14c is processed using ions and free radicals contained in the plasma.

[0074] The control device 11 has a processor, a memory, and an input / output interface. The memory stores programs and process recipes, etc. The processor reads the program from the memory and executes the program, and based on the process recipes stored in the memory, comprehensively controls all parts of the main body 10 of the device via the input / output interface.

[0075] [Details of microwave output device 16]

[0076] Figure 2 This is a block diagram illustrating an example of a microwave output device 16. The microwave output device 16 includes a microwave generating unit 16a, a waveguide 16b, a circulator 16c, waveguides 16d and 16e, a directional coupler 16f, a measuring device 16g, a directional coupler 16h, a measuring device 16i, and a dummy load 16j. The microwave generating unit 16a includes a waveform generating unit 161, an electrical power control unit 162, an attenuator 163, an amplifier 164, an amplifier 165, and a mode converter 166.

[0077] The waveform generation unit 161 generates microwaves of BB (Broadband) and SP (Single Peak) waveforms within a preset frequency range (e.g., 2.4 GHz to 2.5 GHz). A BB waveform is a waveform with a specified bandwidth at a specified center frequency. An SP waveform is a narrow-band waveform with a single peak at a specified frequency. Furthermore, the waveform generation unit 161 can sweep the frequency of the SP waveform from a specified frequency to a specified frequency at a specified scan speed.

[0078] Figure 3 This is a block diagram illustrating an example of the detailed features of the waveform generation unit 161. The waveform generation unit 161 includes, for example, a PLL (Phase Locked Loop) oscillator that outputs microwaves and an IQ digital modulator connected to the PLL oscillator. The waveform generation unit 161 sets the frequency of the microwaves output from the PLL oscillator to a frequency within a set frequency range specified by the control device 11. Furthermore, the waveform generation unit 161 uses the IQ digital modulator to modulate the microwaves output from the PLL oscillator and microwaves having a 90° phase difference compared to the microwaves output from the PLL oscillator. Thus, the waveform generation unit 161 generates microwaves at frequencies within the set frequency range.

[0079] The waveform generation unit 161, for example, inputs N waveform data from the start frequency to the end frequency sequentially according to the scanning speed, performs quantization and inverse Fourier transform, thereby generating frequency-modulated microwaves.

[0080] In this embodiment, the waveform generation unit 161 has waveform data represented by columns of pre-digitized symbols. The waveform generation unit 161 generates I data and Q data by quantizing the waveform data and applying an inverse Fourier transform to the quantized data. Next, the waveform generation unit 161 converts the I data and Q data, which are digital signals, into analog signals. Then, the waveform generation unit 161 extracts low-frequency components from each of the transformed analog signals using an LPF (Low Pass Filter). Next, the waveform generation unit 161 mixes the analog signal with the I component with microwaves output from the PLL, and mixes the analog signal with the Q component with microwaves that have a 90° phase difference compared to the microwaves output from the PLL. Finally, the waveform generation unit 161 synthesizes the two mixed analog signals to generate frequency-modulated microwaves.

[0081] Furthermore, the method for generating microwaves using the waveform generation unit 161 is not limited to... Figure 3The method illustrated can also be used to generate microwaves using DDS (Direct Digital Synthesizer) and VCO (Voltage Controlled Oscillator).

[0082] return Figure 2 Continuing the explanation, a microwave input attenuator 163 is output from the waveform generation unit 161. An electrical power control unit 162 is connected to the attenuator 163. The electrical power control unit 162 can be, for example, a processor. The electrical power control unit 162 controls the attenuation rate of the attenuator 163, causing microwaves with the electrical power specified by the control unit 11 to be output from the microwave output device 16. The microwaves output from the attenuator 163 are output to the mode converter 166 via amplifiers 164 and 165. Amplifiers 164 and 165 amplify the microwaves according to a set amplification rate. The mode converter 166 changes the mode of the microwaves amplified by amplifiers 165.

[0083] The output terminal of the microwave generator 16a is connected to one end of the waveguide 16b. The other end of the waveguide 16b is connected to the first port 261 of the circulator 16c. A directional coupler 16f is provided in the waveguide 16b. Alternatively, the directional coupler 16f may also be provided in the waveguide 16d. The directional coupler 16f branches a portion of the microwave (i.e., traveling wave) output from the microwave generator 16a and transmitted to the circulator 16c, and outputs a portion of this traveling wave to the measuring device 16g. Based on the portion of the traveling wave output from the directional coupler 16f, the measuring device 16g measures the electrical power of the traveling wave transmitted in the waveguide 16d, and outputs the measurement result to the electrical power control unit 162.

[0084] The circulator 16c has a first port 261, a second port 262, and a third port 263. The circulator 16c outputs microwaves input to the first port 261 from the second port 262 and outputs microwaves input to the second port 262 from the third port 263. One end of the tuner 26d is connected to the second port 262 of the circulator 16c. The other end of the tuner 26d is provided with the output terminal 16t of the microwave output device 16.

[0085] One end of the waveguide 16e is connected to port 263 of the circulator 16c, and a dummy load 16j is connected to the other end of the waveguide 16e. A directional coupler 16h is provided in the waveguide 16e. Alternatively, the directional coupler 16h may also be provided in the waveguide 16d. The directional coupler 16h branches a portion of the microwave (i.e., the reflected wave) transmitted to the waveguide 16e and outputs a portion of this reflected wave to the measuring device 16i. Based on the portion of the reflected wave output from the directional coupler 16h, the measuring device 16i measures the electrical power of the reflected wave transmitted in the waveguide 16d and outputs the measurement result to the electrical power control unit 162.

[0086] The dummy load 16j receives microwaves transmitted in the waveguide 16e and absorbs them. The dummy load 16j, for example, converts the microwaves into heat.

[0087] The power control unit 162 controls the waveform generation unit 161 and the attenuator 163 so that the difference between the power of the traveling wave measured by the measuring device 16g and the power of the reflected wave measured by the measuring device 16i becomes the power specified by the control device 11. The difference between the power of the traveling wave measured by the measuring device 16g and the power of the reflected wave measured by the measuring device 16i is the power supplied to the processing container 12.

[0088] Tuner 26 is disposed in waveguide 21 and adjusts the protruding position of movable plate based on control signals from control device 11 to match the impedance on the microwave output device 16 side with the impedance on the processing container 12 side. Tuner 26 actuates movable plate via drive circuitry and actuator (not shown). Alternatively, adjustment of the protruding position of movable plate can also be achieved using a stub structure.

[0089] [Frequency distribution of the electric power of the reflected wave]

[0090] Figure 4 This is a diagram illustrating an example of the frequency distribution of the electric power of the reflected wave before plasma generation. Figure 4 This graph is obtained by plotting the electrical power of the reflected wave per frequency when a microwave of the SP waveform is supplied to the processing container 12, without generating plasma. Figure 4 In the example, the electrical power of the microwaves of the SP waveform supplied to the processing container 12 is 30W.

[0091] exist Figure 4 In the example, the electric power of the reflected wave is minimized at frequency fa. If microwaves at frequency fa are supplied into the processing container 12, the electric power of the reflected wave can be reduced compared to the case where microwaves at frequency fb are supplied into the processing container 12. Therefore, as long as microwaves at frequency fa are supplied into the processing container 12, the electric power of the microwaves can be supplied into the processing container 12 efficiently, and plasma can be generated efficiently within the processing container 12.

[0092] However, due to mechanical errors in the processing container 12 (such as dimensional errors and installation errors of constituent components), there are variations in the impedance within the processing container 12. Consequently, the frequency at which the reflected wave's electrical power is minimized varies for each processing container 12. Furthermore, even with the same processing container 12, the accumulation of reaction byproducts (so-called deposits) and the consumption of consumable components change due to repeated plasma treatment of the substrate WP. As a result, with each additional plasma treatment of the substrate WP, the impedance within the processing container 12 changes, and the frequency at which the reflected wave's electrical power is minimized also changes. Moreover, during cleaning, the amount of deposit accumulation changes before and after cleaning, thus altering the impedance within the processing container 12 and consequently changing the frequency at which the reflected wave's electrical power is minimized.

[0093] Therefore, in this embodiment, for the multiple processing containers 12, after processing the multiple substrates WP or after performing a cleaning, the frequency at which the electric power of the reflected wave is minimized is determined. Then, a frequency band containing the frequency at which the electric power of the reflected wave is minimized is predetermined. During plasma generation, microwaves with a BB waveform of the determined frequency band are supplied into the processing container 12. As a result, the electric power of at least a portion of the frequencies contained in the supplied microwaves can be efficiently supplied into the processing container 12, thereby enabling more reliable plasma generation.

[0094] Figure 5 This is a diagram illustrating an example of the frequency distribution of the electric power of the reflected wave after plasma generation. After plasma generation, the frequency at which the electric power of the reflected wave is minimized varies not only according to the state of the processing container 12 but also according to the state of the plasma itself. For example, as... Figure 5 As illustrated, when the electrical power of the microwaves supplied to the processing container 12 varies, the state of the generated plasma changes, and the frequency at which the electrical power of the reflected wave is minimized also changes. Figure 5 In the examples, when the microwave power is 1000W, the reflected wave power is minimum at frequency fa. Furthermore, when the microwave power is 1400W, the reflected wave power is minimum at frequency fb. Moreover, when the microwave power is 2000W, the reflected wave power is minimum at frequency fc.

[0095] Furthermore, after plasma generation, impedance matching between the output impedance of the microwave output device 16 and the load impedance is performed using tuner 26. In this case, when the electrical power of the reflected wave from the processing container 12 is high, it is difficult to perform impedance matching correctly. Therefore, in this embodiment, microwaves with a bandwidth less than or equal to the bandwidth of the microwaves supplied before plasma generation are supplied after plasma generation. As a result, impedance matching after plasma generation can be performed with high precision, and plasma can be stably maintained.

[0096] [Plasma Treatment Methods]

[0097] Figure 6 This is a flowchart illustrating an example of the plasma processing method according to the first embodiment. Figure 6 The exemplified processing is achieved by the control device 11 controlling various parts of the main body 10 of the control device.

[0098] First, the gate G is opened, and using a robotic arm (not shown), the untreated substrate WP is fed into the processing container 12 through the opening 12c and placed on the electrostatic chuck 14c (S10). Then, the gate G is closed. Next, the control device 11 opens the valve 38b and controls the flow controller 38c to supply a pre-set flow rate of processing gas into the processing container 12, thereby initiating the gas supply into the processing container 12 (S11). Then, the control device 11 controls the exhaust device 56 to regulate the pressure inside the processing container 12 (S12).

[0099] Next, the control device 11 controls the microwave output device 16 to supply a first microwave to the processing container 12 via the antenna 18 (S13). The first microwave has a bandwidth W1 and is a BB waveform microwave with a center frequency f1. In this embodiment, for multiple processing containers 12, after processing multiple substrates WP and / or after cleaning, the frequency distribution of the reflected wave's electrical power is measured respectively. Then, the bandwidth W1 and the center frequency f1 are determined such that the frequency that minimizes the reflected wave's electrical power in each measured frequency distribution is included in the microwave's frequency range. Thus, in step S13, for example, the microwave is supplied to the processing container 12. Figure 7A The microwave has the frequency distribution shown. Bandwidth W1 is an example of a first bandwidth, and center frequency f1 is an example of a first frequency. Furthermore, step S13 is an example of step a.

[0100] Next, the control device 11 determines whether a preset time t1 (e.g., tens to hundreds of milliseconds) has elapsed since the start of the first microwave supply (S14). Time t1 is the time from the supply of the first microwave until plasma is generated in the processing container 12. If time t1 has not elapsed (S14: No), the process shown in step S14 is executed again.

[0101] On the other hand, after time t1 has elapsed (S14: Yes), the control device 11 controls the microwave output device 16 to replace the first microwave and supply a second microwave into the processing container 12 (S15). The second microwave has a bandwidth W2 and is a BB waveform microwave with a center frequency f2. In this embodiment, the bandwidth W2 is a bandwidth less than or equal to the bandwidth W1. Furthermore, in this embodiment, the center frequency f2 is a frequency different from the center frequency f1.

[0102] Here, the state within the processing container 12 before plasma generation differs from the state within the processing container 12 after plasma generation. Therefore, the frequencies at which the reflected wave's electrical power is minimized differ significantly between the two processes. Consequently, by setting the center frequency f1 of the first microwave supplied before plasma generation to a different frequency than the center frequency f2 of the second microwave supplied after plasma generation, electrical power corresponding to the state within the processing container 12 can be supplied. This allows for more reliable plasma generation and stable plasma maintenance.

[0103] In this embodiment, for multiple processing containers 12, after processing multiple substrates WP and / or after cleaning, the frequency distribution of the reflected wave's electrical power is measured respectively. Then, the bandwidth W2 and center frequency f2 are determined such that the frequency in each measured frequency distribution that minimizes the reflected wave's electrical power is within the microwave frequency range. Therefore, in step S15, for example, the processing container 12 is supplied with... Figure 7B The microwave has the frequency distribution shown. Bandwidth W2 is an example of a second bandwidth, and center frequency f2 is an example of a second frequency. Furthermore, step S15 is an example of step b.

[0104] Next, the control device 11 controls the RF power supply 58 to supply bias power to the base station 14a via the matching unit 60 and the power supply bar 62 (S16). As a result, plasma processing such as etching of the substrate WP begins.

[0105] Next, the control device 11 determines whether a preset time t2 (e.g., a few seconds to a few minutes) has elapsed since the start of the second microwave supply (S17). Time t2 is the time from the start of the second microwave supply until the plasma treatment, such as etching, is completed on the substrate WP. If time t2 has not elapsed (S17: No), the process shown in step S17 is executed again.

[0106] On the other hand, after time t2 has elapsed (S17: Yes), control device 11 controls microwave output device 16 to stop the supply of the second microwave (S18). Then, control device 11 closes valve 38b to stop the supply of processing gas to the processing container 12 (S19). Then, control device 11 controls exhaust device 56 to exhaust the processing gas in the processing container 12 (S20). Then, gate G is opened, and the processed substrate WP is delivered from the processing container 12 using a robotic arm (not shown) (S21). Then, the plasma processing shown in this flowchart ends.

[0107] The first embodiment has been described above. The plasma processing apparatus 1 of this embodiment includes a processing container 12, a gas supply unit 38, a microwave output device 16, and a control device 11. The processing container 12 houses the substrate WP. The gas supply unit 38 supplies processing gas into the processing container 12. The microwave output device 16 generates plasma from the processing gas supplied to the processing container 12 by supplying electrical power to the processing container 12, and uses the generated plasma to process the substrate WP. The control device 11 controls the microwave output device 16. Furthermore, the control device 11 performs the following steps: step a, when generating plasma from the processing gas, controlling the microwave output device 16 to supply electrical power to the processing container 12 containing frequency components contained in a frequency band including bandwidth W1; and step b, when using the generated plasma to process the substrate WP, controlling the microwave output device 16 to supply electrical power to the processing container 12 containing frequency components contained in a frequency band including bandwidth W2 less than or equal to bandwidth W1. This allows for more reliable plasma generation and stable plasma maintenance.

[0108] Furthermore, in the above embodiment, when generating plasma from the processing gas, the control device 11 supplies electrical power containing frequency components within a bandwidth W1 centered at frequency f1 into the processing container 12. Also, when processing the substrate WP with the generated plasma, the control device 11 supplies electrical power containing frequency components within a bandwidth W2 centered at a frequency different from f1 into the processing container 12. This allows for more reliable plasma generation and stable plasma maintenance.

[0109] (Second Implementation)

[0110] In the first embodiment, during plasma processing of the substrate WP, microwaves with a BB waveform and a bandwidth W2 centered at frequency f2 are supplied into the processing container 12. In contrast, in this embodiment, during plasma processing of the substrate WP, microwaves with an SP waveform having a frequency f2 are supplied into the processing container 12. This reduces reflected waves and allows for more precise impedance matching during plasma processing of the substrate WP. Furthermore, the structure and use of the plasma processing apparatus 1 in this embodiment... Figures 1-3 The plasma processing apparatus 1 described in the first embodiment is the same, so detailed description is omitted.

[0111] [Plasma Treatment Methods]

[0112] Figure 8 This is a flowchart illustrating an example of the plasma processing method according to the second embodiment. Figure 8 The processing illustrated herein is achieved by controlling various parts of the control device body 10 via the control device 11. Furthermore, except for the points described below, in Figure 8 In the example processing, the annotations are related to... Figure 6 The treatment of the same reference numerals is the same as that of the use of Figure 6 The processing is the same, so detailed explanations are omitted.

[0113] When the control device 11 determines that a preset time t1 has elapsed since the supply of the first microwave (S14: Yes), it controls the microwave output device 16 to supply a third microwave into the processing container 12 instead of the first microwave (S30). The third microwave is, for example,... Figure 9 As shown, the microwave has a single peak at frequency f2, forming an SP waveform. Next, the processing after step S16 is performed.

[0114] The second embodiment has been described above. In this embodiment, the plasma processing apparatus 1 supplies microwaves with an SP waveform centered at frequency f2 into the processing container 12 after generating plasma. This reduces reflected waves and enables impedance matching during plasma processing of the substrate WP with higher precision.

[0115] (Third Implementation)

[0116] In the first embodiment, during plasma generation, microwaves with a bandwidth W1 and a BB waveform centered at frequency f1 are supplied to the processing container 12. After plasma generation, microwaves with a bandwidth W2 and a BB waveform centered at frequency f2 are supplied to the processing container 12. In contrast, in this embodiment, during the period from plasma generation to the start of plasma processing on the substrate WP, microwaves with a bandwidth W3 and a BB waveform centered at frequency f3 are supplied to the processing container 12. Frequency f3 is the frequency between frequency f1 and frequency f2, and bandwidth W3 is the bandwidth between bandwidth W1 and bandwidth W2. This suppresses plasma ignition caused by abrupt changes in the bandwidth and center frequency of the microwaves supplied to the processing container 12. Furthermore, the structure and use of the plasma processing apparatus 1 in this embodiment... Figures 1-3 The plasma processing apparatus 1 described in the first embodiment is the same, so detailed description is omitted.

[0117] [Plasma Treatment Methods]

[0118] Figure 10 This is a flowchart illustrating an example of the plasma processing method according to the third embodiment. Figure 10 The processing illustrated herein is achieved by controlling various parts of the control device body 10 via the control device 11. Furthermore, except for the points described below, in Figure 10 In the example processing, the annotations are related to... Figure 6 The treatment of the same reference numerals is the same as that of the use of Figure 6 The processing is the same, so detailed explanations are omitted.

[0119] If the control device 11 determines that a preset time t1 has elapsed since the first microwave supply began (S14: Yes), it controls the microwave output device 16 to supply a fourth microwave to the processing container 12 instead of the first microwave (S40). The fourth microwave is a BB waveform with a bandwidth W3 centered at frequency f3. Then, the control device 11 determines whether a preset time t3 (e.g., tens to hundreds of milliseconds) has elapsed since the fourth microwave supply began (S41). If no time t3 has elapsed (S41: No), the process shown in step S41 is executed again. On the other hand, if time t3 has elapsed (S41: Yes), the process shown in step S15 and later is executed.

[0120] In this embodiment, in step S13, for example Figure 11A As shown, microwaves with a bandwidth W1 centered at frequency f1 and a BB waveform are supplied into the processing container 12. Then, in step S40, for example... Figure 11B As shown, microwaves with a bandwidth W3 centered at frequency f3 and a BB waveform are supplied into the processing container 12. Then, in step S15, for example... Figure 11C As shown, microwaves with a BB waveform centered at frequency f2 and a bandwidth W2 are supplied into the processing container 12. Frequency f3 is the frequency between frequencies f1 and f2, and bandwidth W3 is the width between bandwidth W1 and bandwidth W2. This allows for the suppression of plasma ejection caused by abrupt changes in the bandwidth and center frequency of the microwaves supplied into the processing container 12.

[0121] The third embodiment has been described above. In this embodiment, the control device 11 supplies electrical power to the processing container 12 from the time plasma is generated from the processing gas until the processing of the substrate WP begins with the generated plasma. This power includes frequency components contained in a frequency band centered at a frequency f3 between frequencies f1 and f2 and having a bandwidth W3 between bandwidth W1 and bandwidth W2. As a result, the generated plasma can be stably maintained.

[0122] (Fourth Implementation)

[0123] In the first to third embodiments described above, for multiple processing containers 12, after processing multiple substrates WP and / or after cleaning, the frequency at which the reflected wave's electrical power is minimized is determined in advance. Then, a frequency band is determined, the frequency of which includes the frequency at which the reflected wave's electrical power is minimized, and during plasma generation, microwaves of the determined frequency band with a BB waveform are supplied into the processing container 12. In contrast, in this embodiment, before plasma generation, microwaves with an SP waveform are supplied into the processing container 12, and the frequency of these microwaves is swept to determine the frequency distribution of the reflected wave's electrical power. Then, based on the measured frequency distribution of the reflected wave's electrical power, the bandwidth W1 and center frequency f1 of the BB waveform microwaves to be supplied during plasma generation are determined. Therefore, the bandwidth W1 and center frequency f1 can be determined in accordance with the environment within the processing container 12 during plasma generation, thereby enabling more reliable plasma generation. Furthermore, the structure and use of the plasma processing apparatus 1 in this embodiment... Figures 1-3 The plasma processing apparatus 1 described in the first embodiment is the same, so detailed description is omitted.

[0124] [Plasma Treatment Methods]

[0125] Figure 12 This is a flowchart illustrating an example of the plasma processing method according to the fourth embodiment. Figure 12 The processing illustrated herein is achieved by controlling various parts of the control device body 10 via the control device 11. Furthermore, except for the points described below, in Figure 12 In the example processing, the annotations are related to... Figure 6 The treatment of the same reference numerals is the same as that of the use of Figure 6The processing is the same, so detailed explanations are omitted.

[0126] After adjusting the pressure inside the processing container 12, the control device 11 supplies SP-wavelength microwaves into the processing container 12 and measures the frequency distribution of the reflected wave's electrical power by sweeping the frequency of the microwaves (S50). Furthermore, if the frequency distribution of the reflected wave's electrical power differs depending on the magnitude of the supplied electrical power, it is preferable to use SP-wavelength microwaves with the same electrical power as those supplied during plasma generation to measure the frequency distribution of the reflected wave's electrical power. Then, based on the measured frequency distribution, the control device 11 determines the center frequency f1 of the BB-wavelength microwaves to be supplied during plasma generation (S51). Then, the processing described after step S13 is performed.

[0127] In this embodiment, in step S50, for example, measuring... Figure 13 The frequency distribution of the reflected wave's electrical power is shown. Then, in step S51, multiple peaks with low reflected wave electrical power that bulge towards lower power are determined within a pre-set frequency band W0 (e.g., 2410MHz to 2490MHz). Next, among the determined peaks, frequencies corresponding to a pre-set number of peaks are determined in ascending order of reflected wave electrical power. Figure 13 In the example, three peaks are determined in order of increasing electric power of the reflected wave, and the corresponding frequencies fa, fb, and fc are determined for each peak. Next, for example... Figure 13 As shown, the bandwidth of the frequency band containing all the determined frequencies is defined as bandwidth W1, and the center frequency of this frequency band is defined as center frequency f1. Therefore, microwave electrical power can be supplied to the processing container 12 more efficiently, corresponding to the environment inside the processing container 12 during plasma generation, and plasma can be generated more reliably.

[0128] Furthermore, the method for determining the center frequency f1 of the first microwave is not limited to... Figure 13 The method is illustrated in the example. For example, it can also be as follows: Figure 14 As shown, the frequency fa that minimizes the electrical power of the reflected wave is determined as the center frequency f1. In this case, the bandwidth W1 can be either a pre-set bandwidth or a bandwidth that includes all frequencies corresponding to a pre-set number of peaks in ascending order of the electrical power of the reflected wave.

[0129] The fourth embodiment has been described above. In this embodiment, the control device 11 supplies microwaves with electrical power peaking at a set frequency into the processing container 12, and sweeps the frequency of this peak to measure the frequency distribution of the electrical power of the reflected wave from the processing container 12. Then, based on the frequency distribution of the electrical power of the reflected wave, the control device 11 determines the bandwidth W1 and the center frequency f1. Therefore, plasma can be generated more reliably, corresponding to the environment inside the processing container 12 during plasma generation.

[0130] [Other situations]

[0131] Furthermore, the technology disclosed in this application is not limited to the above-described embodiments, and various modifications can be made within the scope of its spirit.

[0132] For example, in the embodiments described above, the center frequency f1 of the microwaves supplied to the processing container 12 during plasma generation is different from the center frequency f2 of the microwaves supplied to the processing container 12 during plasma processing. However, the technology disclosed herein is not limited to this, and the center frequencies f1 and f2 may be the same.

[0133] Furthermore, for example, in the embodiments described above, the bandwidth W1 of the microwaves supplied to the processing container 12 during plasma generation is different from the bandwidth W2 of the microwaves supplied to the processing container 12 during plasma processing; however, the technology disclosed herein is not limited to this. Alternatively, the bandwidths W1 and W2 may be the same.

[0134] Furthermore, for example, in the embodiments described above, a plasma processing apparatus 1 that uses plasma generated by electrical power at a frequency of microwave band frequency for processing has been used as an example; however, the technology disclosed herein is not limited to this. Alternatively, a plasma processing apparatus that uses plasma generated by electrical power at a frequency lower than microwave band frequency for processing can also utilize the technology disclosed herein. A frequency lower than microwave band frequency is, for example, a frequency in the HF (High Frequency) band (3–30 MHz).

[0135] Furthermore, in the third embodiment described above, during the period from plasma generation to the start of plasma processing of the substrate WP, a third microwave with a frequency between frequency f1 and frequency f2 as its center and a bandwidth between bandwidth W1 and bandwidth W2 is supplied. However, the technology disclosed herein is not limited to this. For example, during the period from plasma generation to the start of plasma processing of the substrate WP, microwaves with a center frequency that slowly changes from frequency f1 to frequency f2 and a bandwidth that slowly changes from bandwidth W1 to bandwidth W2 over time may also be supplied. In this case, the changes in center frequency and bandwidth over time may be either stepwise or continuous.

[0136] Furthermore, in the above embodiments, plasma etching was described as an example of plasma processing, but the technology disclosed herein is not limited thereto. The technology disclosed herein can be applied to any plasma-using process, such as film formation, modification, or cleaning processes.

[0137] Furthermore, while the above-described embodiment uses microwave plasma as an example of a plasma source, the technology disclosed herein is not limited to this. For example, capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) can also be used as plasma sources.

[0138] Furthermore, the embodiments disclosed herein should be considered illustrative in all respects and not restrictive. In fact, the above-described embodiments can be implemented in various ways. Moreover, the above-described embodiments can be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

Claims

1. A plasma processing apparatus characterized by comprising: An object of the present application is to provide a plasma processing apparatus and a plasma processing method, which can appropriately control the frequency of the electric power supplied to a processing container. The plasma processing apparatus includes: a processing container that accommodates a substrate; a gas supply unit that supplies a processing gas into the processing container; an electric power supply unit that generates plasma from the processing gas supplied into the processing container by supplying electric power into the processing container, and processes the substrate with the generated plasma; and a control device that controls the electric power supply unit, the control device performs the following steps: step a, during generation of the plasma from the processing gas, controls the electric power supply unit to simultaneously supply electric power containing a plurality of different frequency components included in a frequency band of a first bandwidth into the processing container; and step b, during processing of the substrate with the generated plasma, controls the electric power supply unit to simultaneously supply electric power containing a plurality of different frequency components included in a frequency band of a second bandwidth narrower than the first bandwidth into the processing container.

2. The plasma processing apparatus according to claim 1, wherein the control device, in the step b, supplies electric power having a single peak at a predetermined frequency as the electric power containing the frequency components included in the frequency band of the second bandwidth into the processing container.

3. The plasma processing apparatus according to claim 1 or 2, wherein the control device, during generation of the plasma from the processing gas, supplies electric power containing frequency components included in a frequency band of the first bandwidth centered on a first frequency into the processing container, during processing of the substrate with the generated plasma, supplies electric power containing frequency components included in a frequency band of the second bandwidth centered on a second frequency different from the first frequency into the processing container.

4. The plasma processing apparatus according to claim 3, wherein the control device, during a period from generation of the plasma from the processing gas to start of processing of the substrate with the generated plasma, supplies electric power containing frequency components included in a frequency band of a third bandwidth into the processing container, the frequency band of the third bandwidth being a frequency band centered on a frequency between the first frequency and the second frequency, and the third bandwidth being a bandwidth between the first bandwidth and the second bandwidth.

5. The plasma processing apparatus according to claim 3, wherein the control device supplies electric power having a single peak at a predetermined frequency into the processing container, and sweeps the frequency of the peak, measures a frequency distribution of reflected waves from the processing container, and determines the first bandwidth and the first frequency based on the frequency distribution of the reflected waves.

6. A plasma processing method, which is an electric power control method in a plasma processing apparatus, the plasma processing apparatus including: a processing container that accommodates a substrate; a gas supply unit that supplies a processing gas into the processing container; an electric power supply unit that generates plasma from the processing gas supplied into the processing container by supplying electric power into the processing container, and processes the substrate with the generated plasma; and a control device that controls the electric power supply unit, the control device performs the following steps: step a, during generation of the plasma from the processing gas, controls the electric power supply unit to simultaneously supply electric power containing a plurality of different frequency components included in a frequency band of a first bandwidth into the processing container; and step b, during processing of the substrate with the generated plasma, controls the electric power supply unit to simultaneously supply electric power containing a plurality of different frequency components included in a frequency band of a second bandwidth narrower than the first bandwidth into the processing container. a control device that controls the electric power supply section, in the plasma processing method, the control device performs the following steps: step a, when generating plasma from the processing gas, controlling the electric power supply section to supply electric power containing a plurality of different frequency components included in a frequency band of a first bandwidth to the inside of the processing vessel simultaneously; and step b, when processing the substrate with the generated plasma, controlling the electric power supply section to supply electric power containing a plurality of different frequency components included in a frequency band of a second bandwidth narrower than the first bandwidth to the inside of the processing vessel simultaneously.

7. The plasma processing method according to claim 6, wherein: in the step b, as the electric power containing frequency components included in the frequency band of the second bandwidth, electric power having a single peak at a predetermined frequency is supplied to the inside of the processing vessel.

8. The plasma processing method according to claim 6 or 7, wherein: when generating plasma from the processing gas, electric power containing frequency components included in a frequency band of the first bandwidth centered on a first frequency is supplied to the inside of the processing vessel, when processing the substrate with the generated plasma, electric power containing frequency components included in a frequency band of the second bandwidth centered on a second frequency different from the first frequency is supplied to the inside of the processing vessel.

9. The plasma processing method according to claim 8, wherein: during a period from the generation of plasma from the processing gas to the start of processing of the substrate with the generated plasma, electric power containing frequency components included in a frequency band of a third bandwidth is supplied to the inside of the processing vessel, the frequency band of the third bandwidth being a frequency band centered on a frequency between the first frequency and the second frequency, the third bandwidth being a bandwidth between the first bandwidth and the second bandwidth.

10. The plasma processing method according to claim 8, wherein: electric power having a single peak at a set frequency is supplied to the inside of the processing vessel, the frequency of the peak is swept, a frequency distribution of reflected waves from the processing vessel is measured, and the first bandwidth and the first frequency are determined based on the frequency distribution of the reflected waves.

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