JP2020126998A - Plasma processing device - Google Patents

Abstract

To provide a plasma processing device which can suppress the excessive dissociation of gas in a chamber to suppress the re-dissociation of a reaction product produced by plasma etching.SOLUTION: A plasma processing device of an exemplary embodiment comprises: a radio-frequency power source serving to generate a radio-frequency power for plasma generation; and a bias power source serving to periodically apply a pulse-like DC voltage of negative polarity to a lower electrode in order to lead ions into a substrate-supporting unit. The radio-frequency power source supplies a radio-frequency power as one or more pulses in a period during which the pulse-like DC voltage of negative polarity is not applied to the lower electrode. The radio-frequency power source stops supplying the radio-frequency power in a period during which the pulse-like DC voltage of negative polarity is applied to the lower electrode. Of the one or more pulses, each pulse has a power level which gradually increases from a start point of time to a point when a peak arises.SELECTED DRAWING: Figure 1

Description

Example embodiments of the present disclosure relate to plasma processing apparatus.

Plasma processing equipment is used in plasma etching of substrates. The plasma processing apparatus includes a chamber, a substrate support, and two high frequency power supplies. The substrate support includes a lower electrode. The substrate support is configured to support the substrate within the chamber. Gas is supplied into the chamber for plasma processing. High frequency power is supplied from one of the two high frequency power supplies to generate plasma from the gas. In addition, the high frequency bias power is supplied to the lower electrode from the other of the two high frequency power supplies. Such a plasma processing apparatus is described in Patent Document 1.

JP-A-2000-173993

The present disclosure provides a technique of suppressing excessive dissociation of gas in a chamber and suppressing re-dissociation of reaction products generated by plasma etching.

In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a high frequency power supply, and a bias power supply. The substrate support has a lower electrode. The substrate support is configured to support the substrate within the chamber. The high frequency power supply is configured to generate high frequency power to generate plasma from the gas within the chamber. The bias power source is electrically connected to the lower electrode and is configured to generate bias power for attracting ions to the substrate support. The bias power source is configured to periodically generate a pulsed negative DC voltage as bias power. The high frequency power supply is configured to supply the high frequency power as one or more pulses in the first period when the pulsed negative DC voltage is not applied to the lower electrode. The high frequency power supply is configured to stop the supply of the high frequency power during the second period in which the pulsed negative DC voltage is applied to the lower electrode. The radio frequency power supply generates the radio frequency power such that each of the one or more pulses has a power level that gradually increases from the start time to the time when the peak appears.

According to one exemplary embodiment, it is possible to suppress excessive dissociation of gas in the chamber and suppress re-dissociation of reaction products generated by plasma etching.

1 is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment. It is a figure which shows the structure of the high frequency power supply and bias power supply of the plasma processing apparatus which concerns on one example embodiment. 3 is an exemplary timing chart of high frequency power, ion density, electron temperature, and bias power. FIG. 4A is a diagram showing an example of a waveform of combined power of a plurality of power components, and FIG. 4B is a diagram showing a power spectrum of the combined power shown in FIG. FIG. 4C is a diagram showing an example of the waveform of the high frequency power HF. FIG. 5A is a diagram showing an example of a waveform of combined power of a plurality of power components, and FIG. 5B is a diagram showing a power spectrum of the combined power shown in FIG. FIG. 5C is a diagram showing an example of the waveform of the high frequency power HF. It is a figure which shows schematically the plasma processing apparatus which concerns on another exemplary embodiment. It is a figure which shows the structure of the high frequency power supply and bias power supply of the plasma processing apparatus which concerns on another exemplary embodiment. 6 is another exemplary timing chart of high frequency power, ion density, electron temperature, and bias power. 6 is yet another exemplary timing chart of radio frequency power, ion density, electron temperature, and bias power. 7 is another exemplary timing chart of high frequency power and bias power. It is a figure which shows the structure of the high frequency power supply which concerns on another exemplary embodiment.

Various exemplary embodiments are described below.

In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a high frequency power supply, and a bias power supply. The substrate support has a lower electrode. The substrate support is configured to support the substrate within the chamber. The high frequency power supply is configured to generate high frequency power to generate plasma from the gas within the chamber. The bias power source is electrically connected to the lower electrode and is configured to generate bias power for attracting ions to the substrate support. The bias power supply is configured to periodically generate a pulsed negative DC voltage as bias power. The high frequency power supply is configured to supply the high frequency power as one or more pulses in the first period when the pulsed negative DC voltage is not applied to the lower electrode. The high frequency power supply is configured to stop the supply of the high frequency power during the second period in which the pulsed negative DC voltage is applied to the lower electrode. The radio frequency power supply generates the radio frequency power such that each of the one or more pulses has a power level that gradually increases from the start time to the time when the peak appears.

During the second period in which the pulsed negative DC voltage is applied to the lower electrode, the ions are accelerated from the plasma toward the substrate to etch the substrate. Therefore, the reaction product is released from the substrate in the second period. When the electron temperature of plasma is high, re-dissociation of reaction products occurs. The substance generated by the re-dissociation of the reaction product may be deposited on the substrate. In the above embodiment, since the high frequency power is not supplied in the second period, the electron temperature of plasma is low in the second period. Therefore, according to the above embodiment, re-dissociation of the reaction product is suppressed. Further, in the first period in which the pulsed negative DC voltage is not applied to the lower electrode, the high frequency power is supplied as one or more pulses. The power level of each of the one or more pulses gradually increases to its peak. Therefore, the overshoot of the electron temperature is suppressed. As a result, according to the above embodiment, excessive dissociation of gas is suppressed.

In one exemplary embodiment, the plasma processing apparatus may further include a controller configured to control the bias power supply to set the phase of the period of the pulsed negative polarity DC voltage. According to this embodiment, it is possible to adjust the time difference between the end point of the supply of one or more pulses and the start point of the application of the pulsed negative DC voltage to the lower electrode. Therefore, it is possible to adjust the electron temperature of the plasma before the start of the application of the pulsed negative DC voltage to the lower electrode.

In one exemplary embodiment, the controller may further control the bias power supply to set the duration of the pulsed negative DC voltage. According to this embodiment, it is possible to adjust the time difference between the end point of the application of the pulsed negative DC voltage to the lower electrode and the start point of the supply of one or more pulses.

In another exemplary embodiment, a plasma processing apparatus is also provided. The plasma processing apparatus includes a chamber, a substrate support, a high frequency power supply, and a bias power supply. The substrate support has a lower electrode. The substrate support is configured to support the substrate within the chamber. The high frequency power supply is configured to generate high frequency power to generate plasma from the gas within the chamber. The bias power source is electrically connected to the lower electrode and is configured to generate bias power for attracting ions to the substrate support. The bias power supply is configured to generate high frequency bias power as the bias power. The high frequency power supply is configured to supply the high frequency power as one or more pulses during the first period in which the high frequency bias power output from the bias power supply has a positive voltage. The high frequency power supply is configured to stop the supply of the high frequency power during the second period in which the high frequency bias power output from the bias power supply has a negative voltage. The radio frequency power supply generates the pulsed radio frequency power such that each of the one or more pulses has a power level that gradually increases from the start time to the time when the peak appears.

During the second period in which the high frequency bias power output from the bias power supply has a negative voltage, the ions are accelerated from the plasma toward the substrate and the substrate is etched. Therefore, the reaction product is released from the substrate in the second period. When the electron temperature of plasma is high, re-dissociation of reaction products occurs. The substance generated by the re-dissociation of the reaction product may be deposited on the substrate. In the above embodiment, since the high frequency power is not supplied in the second period, the electron temperature of plasma is low in the second period. Therefore, according to the above embodiment, re-dissociation of the reaction product is suppressed. Further, in the first period in which the high frequency bias power output from the bias power source has a positive voltage, the high frequency power is supplied as one or more pulses. The power level of each of the one or more pulses gradually increases to its peak. Therefore, the overshoot of the electron temperature is suppressed. As a result, according to the above embodiment, excessive dissociation of gas is suppressed.

In one exemplary embodiment, the plasma processing apparatus may further include a controller configured to control the bias power supply to set the phase of the high frequency bias power. According to this embodiment, it is possible to adjust the time difference between the end of the supply of one or more pulses and the time when the potential of the lower electrode has a negative peak.

In one exemplary embodiment, the rise time of each of the one or more pulses may be longer than the minimum rise time of a pulse of high frequency power that can be output from the high frequency power supply.

In one exemplary embodiment, the radio frequency power supply may include a power generator and an output. The power generator is configured to generate high frequency power. The output unit is configured to output the high frequency power generated by the power generator.

In one exemplary embodiment, the high frequency power generated by the power generator includes a plurality of power components. The plurality of power components each have a plurality of frequencies. The plurality of frequencies are set symmetrically with respect to the fundamental frequency at intervals of a predetermined frequency. The envelope of high-frequency power has peaks that appear periodically at time intervals defined by a predetermined frequency or a frequency that is a multiple of twice or more the predetermined frequency. The power level of the high-frequency power is set to be zero in a period excluding the period between the zero-cross region of the envelope immediately before the exit time of each peak and the zero-cross region of the envelope immediately after the exit time. There is.

In one exemplary embodiment, the power generator may include a waveform data generator, a quantizer, an inverse Fourier transform, and a modulator. The quantizer is configured to quantize the waveform data generated by the waveform data generator to generate quantized data. The inverse Fourier transform unit is configured to apply the inverse Fourier transform to the quantized data to generate I data and Q data. The modulator is configured to modulate two reference high frequency signals whose phases are different from each other by 90° by using I data and Q data to generate a modulated high frequency signal. In this embodiment, the power generator is configured to generate high frequency power from the modulated high frequency signal.

In one exemplary embodiment, the power generator may further include an amplifier configured to amplify the modulated radio frequency signal to produce radio frequency power.

In one exemplary embodiment, the radio frequency power supply may be configured such that the rise time of each of the one or more pulses is adjustable.

In one exemplary embodiment, the radio frequency power supply may be configured to sequentially supply the plurality of pulses as one or more pulses in the first period.

Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 shown in FIG. 1 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein.

The chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space 10s is provided inside the chamber body 12. The chamber body 12 is made of, for example, aluminum. A film having corrosion resistance is provided on the inner wall surface of the chamber body 12. The film having corrosion resistance may be a film formed of a ceramic such as aluminum oxide or yttrium oxide.

A passage 12p is formed in the side wall of the chamber body 12. The substrate W passes through the passage 12p when being transferred between the internal space 10s and the outside of the chamber 10. The passage 12p can be opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the chamber body 12.

A support portion 13 is provided on the bottom of the chamber body 12. The support portion 13 is made of an insulating material. The support portion 13 has a substantially cylindrical shape. The support portion 13 extends upward from the bottom portion of the chamber body 12 in the internal space 10s. The support 13 supports the substrate supporter 14. The substrate supporter 14 is configured to support the substrate W in the internal space 10s.

The substrate support 14 has a lower electrode 18 and an electrostatic chuck 20. The substrate supporter 14 may further include an electrode plate 16. The electrode plate 16, the lower electrode 18, and the electrostatic chuck 20 are provided inside the chamber 10. The electrode plate 16 is made of a conductor such as aluminum and has a substantially disc shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a substantially disc shape. The lower electrode 18 is electrically connected to the electrode plate 16.

The electrostatic chuck 20 is provided on the lower electrode 18. The substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and electrodes. The main body of the electrostatic chuck 20 has a substantially disc shape and is made of a dielectric material. The electrode of the electrostatic chuck 20 is a film-shaped electrode and is provided inside the main body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to the DC power supply 20p via the switch 20s. When a voltage from the DC power supply 20p is applied to the electrodes of the electrostatic chuck 20, an electrostatic attractive force is generated between the electrostatic chuck 20 and the substrate W. The generated electrostatic attraction causes the substrate W to be attracted to the electrostatic chuck 20 and held by the electrostatic chuck 20.

A focus ring FR is mounted on the peripheral portion of the substrate supporter 14. The focus ring FR is provided to improve the in-plane uniformity of plasma processing on the substrate W. The focus ring FR has a substantially plate shape and an annular shape. The focus ring FR can be formed of, but not limited to, silicon, silicon carbide, or quartz. The substrate W is arranged on the electrostatic chuck 20 and in a region surrounded by the focus ring FR.

A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (for example, a refrigerant) is supplied to the flow path 18f from a chiller unit 22 provided outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f is returned to the chiller unit 22 via the pipe 22b. In the plasma processing apparatus 1, the temperature of the substrate W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18.

The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies the heat transfer gas (for example, He gas) from the heat transfer gas supply mechanism to the gap between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the substrate support 14. The upper electrode 30 is supported on the upper portion of the chamber body 12 via the member 32. The member 32 is made of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 is a lower surface on the side of the internal space 10s and defines the internal space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor with low Joule heat. The top plate 34 is formed with a plurality of gas discharge holes 34a. The plurality of gas discharge holes 34a penetrate the top plate 34 in the plate thickness direction.

The support body 36 detachably supports the top plate 34. The support 36 is formed of a conductive material such as aluminum. A gas diffusion space 36 a is provided inside the support 36. A plurality of gas holes 36b are formed in the support 36. The plurality of gas holes 36b extend downward from the gas diffusion chamber 36a. The plurality of gas holes 36b communicate with the plurality of gas discharge holes 34a, respectively. A gas inlet 36c is formed in the support 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

A gas source group 40 is connected to the gas supply pipe 38 via a valve group 41, a flow rate controller group 42, and a valve group 43. The gas source group 40 includes a plurality of gas sources. Each of the valve group 41 and the valve group 43 includes a plurality of open/close valves. The flow rate controller group 42 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers of the flow rate controller group 42 is a mass flow controller or a pressure control type flow rate controller. Each of the plurality of gas sources of the gas source group 40 is connected to a gas supply pipe via a corresponding opening/closing valve of the valve group 41, a corresponding flow rate controller of the flow rate controller group 42, and a corresponding opening/closing valve of the valve group 43. 38.

In the plasma processing apparatus 1, the shield 46 is detachably provided along the inner wall surface of the chamber body 12. The shield 46 is also provided on the outer periphery of the support portion 13. The shield 46 prevents the etching by-product from adhering to the chamber body 12. The shield 46 is formed, for example, by forming a film having corrosion resistance on the surface of a member formed of aluminum. The corrosion resistant film may be a film formed from a ceramic such as yttrium oxide.

A baffle plate 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle plate 48 is configured by forming a film having corrosion resistance on the surface of a member formed of aluminum, for example. The corrosion resistant film may be a film formed from a ceramic such as yttrium oxide. A plurality of through holes are formed in the baffle plate 48. An exhaust port 12e is provided below the baffle plate 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 has a vacuum pump such as a pressure control valve and a turbo molecular pump.

The plasma processing apparatus 1 further includes a high frequency power supply 61. The high frequency power supply 61 is configured to generate high frequency power HF. The fundamental frequency of the high frequency power HF is a frequency within the range of 13 MHz to 200 MHz, for example. The high frequency power supply 61 supplies high frequency power HF to generate plasma from the gas in the chamber 10. The high frequency power supply 61 is electrically connected to the lower electrode 18 via the matching unit 62. The matching device 62 has a matching circuit. The matching circuit of the matching device 62 is configured to match the impedance of the high frequency power supply 61 on the load side (lower electrode side) with the output impedance of the high frequency power supply 61. A filter 63 may be provided between the matching unit 62 and the lower electrode 18. The filter 63 is configured to pass the high-frequency power HF and reduce or block other signals going to the high-frequency power supply 61. In addition, in another embodiment, the high frequency power supply 61 may be electrically connected to the upper electrode 30 via the matching unit 62.

The plasma processing apparatus 1 further includes a bias power supply 81. The bias power source 81 is electrically connected to the lower electrode 18. The bias power source 81 is configured to generate a bias power BP for attracting ions to the substrate support 14. The bias power BP is supplied to the lower electrode 18. A filter 83 may be provided between the bias power source 81 and the lower electrode 18. The filter 83 is configured to pass the bias power BP and reduce or block other signals to the bias power supply 81.

Hereinafter, referring to FIG. 2 and FIG. 3 together with FIG. FIG. 2 is a diagram showing a configuration of a high frequency power supply and a bias power supply of the plasma processing apparatus according to one exemplary embodiment. FIG. 3 is an exemplary timing chart of high frequency power (HF), ion density (Ni), electron temperature (Te), and bias power (pulsed negative DC voltage BV).

In one embodiment, the bias power supply 81 is configured to periodically generate the pulsed negative DC voltage BV as the bias power BP at a cycle CP. The DC voltage BV is applied to the lower electrode 18. The repetition frequency of the pulsed DC voltage BV of negative polarity, that is, the reciprocal of the period CP is, for example, a frequency within the range of 1 kHz to 800 kHz.

In one embodiment, the bias power supply 81 may include a DC power supply 81a and a switching element 81b. The DC power supply 81a is a DC power supply that generates a negative DC voltage. The DC power supply 81a may be a variable DC power supply. The switching element 81b is connected between the DC power supply 81a and the lower electrode 18. When the switching element 81b becomes conductive, the DC power supply 81a conducts to the lower electrode 18 and a negative DC voltage is applied to the lower electrode 18. On the other hand, when the switching element 81b is turned off, the DC power supply 81a is electrically disconnected from the lower electrode 18, and the application of the negative DC voltage to the lower electrode 18 is stopped. Due to the state transition of the switching element 81b, a pulsed negative DC voltage BV is generated. The conducting state and the non-conducting state of the switching element 81b are controlled by the control unit 80 described below or another controller.

The high frequency power supply 61 is configured to supply the high frequency power HF as one or more pulses PL in the first period P1. In the case of the plasma processing apparatus 1, the first period P1 is a period in which the pulsed negative DC voltage BV is not applied to the lower electrode 18. In the example shown in FIG. 3, one pulse PL of the high frequency power HF is supplied in the single first period P1.

The high frequency power supply 61 is configured to stop the supply of the high frequency power HF in the second period P2. In the case of the plasma processing apparatus 1, the second period P2 is a period in which the pulsed negative DC voltage BV is applied to the lower electrode 18.

The high frequency power supply 61 generates the high frequency power HF so that each pulse PL has a power level that gradually increases from the start time to the time when the peak appears. The rising time of each pulse PL of the high frequency power HF can be set to a time longer than the minimum rising time of the pulse of the high frequency power that can be output from the high frequency power supply 61.

Ions in the plasma in the chamber 10 are accelerated toward the substrate W in the second period P2. As a result, the substrate W is etched in the second period P2. Therefore, in the second period P2, the reaction product is released from the substrate W. When the electron temperature of the plasma is high, re-dissociation of reaction products occurs in the plasma. The substance generated by the re-dissociation of the reaction product can be deposited on the substrate W. In the plasma processing apparatus 1, since the high frequency power HF is not supplied in the second period P2, the electron temperature of plasma is low in the second period P2. Therefore, according to the plasma processing apparatus 1, the re-dissociation of the reaction product is suppressed. When the re-dissociation of reaction products is suppressed, the formation of deposits on the substrate W is suppressed. As a result, reduction or blockage of the opening formed in the substrate W by plasma etching is suppressed.

In addition, in the first period P1, the high frequency power HF is supplied as one or more pulses PL. The power level of each pulse PL gradually rises to its peak. Therefore, the overshoot of the electron temperature is suppressed. As a result, according to the plasma processing apparatus 1, excessive dissociation of gas is suppressed. Therefore, according to the plasma processing apparatus 1, the substrate W can be etched at a relatively high etching rate.

In one embodiment, the high frequency power supply 61 may include a power generator 61g and an output unit 61a, as shown in FIG. The power generator 61g is configured to generate high frequency power HF. The output unit 61a is configured to output the high frequency power HF generated by the power generator 61g. The output unit 61a is electrically connected to the lower electrode 18 via the matching unit 62.

FIG. 4A is a diagram showing an example of a waveform of combined power of a plurality of power components, and FIG. 4B is a diagram showing a power spectrum of the combined power shown in FIG. FIG. 4C is a diagram showing an example of the waveform of the high frequency power HF. As shown in (c) of FIG. 4, the high frequency power HF is a pulsed high frequency power that is periodically supplied. That is, the high frequency power HF includes the pulses PL that appear periodically.

In one embodiment, the high frequency power HF includes a plurality of power components. The plurality of power components each have a plurality of frequencies. As shown in FIG. 4B, the plurality of frequencies are set symmetrically with respect to the fundamental frequency f ₀ . The fundamental frequency f ₀ is a frequency within the range of 13 MHz to 200 MHz, for example. In one example, the fundamental frequency f ₀ is 40.68 MHz. Further, as shown in FIG. 4B, the plurality of frequencies are set at intervals of a predetermined frequency f _P. In one embodiment, the frequency f _P is the reciprocal of the period CP. In the example illustrated in FIG. 4B, the frequencies of the plurality of power components are f ₀ −(3/2)×f _P , f ₀ −f _P /2, f ₀ +f _P /2, f _0. +(3/2)×f _P.

The envelope of the combined power of the plurality of power components includes a plurality of peak groups, as shown in FIG. Each of the plurality of peak groups includes a plurality of peaks that appear periodically. The plurality of peaks included in each of the plurality of peak groups appear periodically at time intervals T _P. The time interval T _P is the reciprocal of the frequency f _P.

As shown in (c) of FIG. 4, the envelope of the high frequency power HF has peaks that appear at time intervals T _P. In one embodiment, the high frequency power HF is composed of a group of peaks including a peak P _M having a maximum power level among the plurality of peaks. As shown in FIG. 4C, the high frequency power HF is set so that its power level is zero in the period P _A. The period P _A is a period excluding the period P _P. The period P _P is a period in which the peak of the envelope of the high-frequency power HF appears. In one embodiment, the period P _P is the period in which the peaks P _M respectively appear. Each of the periods P _{P is} a period between the zero-cross region Z _A of the envelope immediately before the output instant of the corresponding peak of the envelope of the high-frequency power HF and the zero-cross region Z _B of the envelope immediately after the output instant. is there. The zero-cross area Z _A and the zero-cross area Z _B may be the time points at which the amplitude of the envelope of the high-frequency power HF has a value that can be considered substantially zero. For example, each of the zero-cross area Z _A and the zero-cross area Z _B has a power level of 30% or less or 10% or less with respect to the peak power level of the envelope of the high-frequency power HF at a time when the power level of the envelope has the power level. May be

As shown in FIG. 4C, each pulse of the high frequency power HF has a power level that gradually increases up to its peak. Also, each pulse has a power level that gradually decreases from its peak. The power level of the high-frequency power HF is set to zero in the period P _A excluding the period P _P between the zero cross region Z _A immediately before each pulse and the zero cross region Z _B immediately after each pulse, that is, the period excluding the duration of each pulse. To be done. The high-frequency power HF has a narrow bandwidth. Therefore, according to the high frequency power supply 61 of one embodiment, it is possible to narrow the bandwidth of the pulsed high frequency power HF. Therefore, according to the plasma processing apparatus 1, it is possible to suppress the reflected wave with respect to the high frequency power HF.

In one embodiment, as shown in FIG. 2, the power generator 61g may include a modulation signal generator 64. In one embodiment, the power generator 61g may further include an amplifier 65. The modulated signal generator 64 generates a modulated high frequency signal. The high frequency power HF may be a modulated high frequency signal generated by the modulation signal generator 64. In this case, the amplifier 65 is unnecessary. Alternatively, the high frequency power HF may be generated by the modulated high frequency signal being amplified by the amplifier 65.

In one embodiment, the modulation signal generation unit 64 includes a waveform data generation unit 71, a quantization unit 72, an inverse Fourier transform unit 73, and a modulation unit 74. In one embodiment, the modulation signal generation unit 64 may further include D/A conversion units 75 and 76 and low pass filters 77 and 78. The modulation signal generation unit 64 may be composed of, for example, an FPGA (Field-Programmable Gate Array). Alternatively, the modulation signal generator 64 may be formed of several circuits.

The waveform data generation unit 71 generates waveform data corresponding to the modulated high frequency signal. The waveform data generation unit 71 is configured to acquire a parameter (for example, frequency and phase) for generating the waveform data from the input device, and generate the waveform data using the acquired parameter. The waveform data generator 71 outputs the generated waveform data to the quantizer 72.

The quantizer 72 is configured to quantize the waveform data generated by the waveform data generator 71 to generate quantized data. The inverse Fourier transform unit 73 is configured to apply an inverse Fourier transform to the quantized data to generate I data (in-phase component) and Q data (quadrature phase component). The I data and the Q data are input to the modulator 74 via the D/A converters 75 and 76 and the low pass filters 77 and 78, respectively.

The modulation unit 74 is configured to respectively modulate two reference high frequency signals whose phases are different from each other by 90° by using the input I data and Q data and generate a modulated high frequency signal.

In one embodiment, the modulator 74 includes a PLL oscillator 74a (Phase Locked Loop oscillator), a phase shifter 74b, mixers 74c and 74d, and a combiner 74e.

The PLL oscillator 74a is configured to generate a reference high frequency signal. The reference high frequency signal is input to the mixer 74c. Further, the reference high frequency signal is input to the phase shifter 74b. The phase shifter 74b is configured to generate a reference high frequency signal having a phase difference of 90° with respect to the reference high frequency signal input to the mixer 74c. Specifically, the phase shifter 74b is configured to shift the phase of the input reference high frequency signal by 90°. The reference high frequency signal generated by the phase shifter 74b is input to the mixer 74d.

The mixer 74c is configured to multiply the input reference high frequency signal and the I data. The signal generated by the multiplication of the mixer 74c is input to the combiner 74e. The mixer 74d is configured to multiply the input reference high frequency signal and the Q data. The signal generated by the multiplication of the mixer 74d is input to the combiner 74e. The combiner 74e is configured to add signals input from the mixer 74c and the mixer 74d to generate a modulated high frequency signal.

In one embodiment, the plasma processing apparatus 1 may further include the controller 80. The control unit 80 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, and a signal input/output interface. The control unit 80 controls each unit of the plasma processing apparatus 1. In the control unit 80, an operator can use the input device to input a command to manage the plasma processing apparatus 1. Further, in the control unit 80, the display device can visualize and display the operating status of the plasma processing apparatus 1. Further, the storage unit of the control unit 80 stores a control program and recipe data. The control program is executed by the processor of the control unit 80 in order to execute various processes in the plasma processing apparatus 1. The processor of the control unit 80 executes the control program and controls the respective units of the plasma processing apparatus 1 according to the recipe data, so that the plasma processing is executed in the plasma processing apparatus 1.

In one embodiment, the control unit 80 or another controller may control the phase of the bias power supply 81 in order to set the phase of the cycle CP of the DC voltage BV. According to this embodiment, the time difference T1 (see FIG. 3) between the end point of the supply of the pulse PL and the start point of the application of the pulsed negative DC voltage BV to the lower electrode 18 can be adjusted. It will be possible. Therefore, the electron temperature of the plasma can be adjusted before the application of the pulsed negative DC voltage BV to the lower electrode 18.

More specifically, the control unit 80 or another controller controls the bias power supply 81 so as to set the phase of the negative DC voltage BV, that is, the timing of starting the supply of the negative DC voltage BV. In one embodiment, the controller 80 or another controller controls the timing at which the switching element 81b switches from the non-conducting state to the conducting state. Thereby, the time difference T1 is controlled.

In one embodiment, the controller 80 or another controller may further control the bias power supply 81 to set the duration PW (FIG. 3) of the pulsed DC voltage BV having the negative polarity. In one embodiment, the controller 80 or another controller sets the duration PW by controlling the length of time that the switching element 81b remains conductive. This makes it possible to adjust the time difference T2 (FIG. 3) between the end time of the application of the pulsed negative DC voltage BV to the lower electrode 18 and the start time of the supply of the pulse PL.

Hereinafter, reference will be made to FIGS. 5A, 5B, and 5C. In another example, as shown in FIG. 5B, the frequencies of the plurality of power components of the high frequency power HF are f ₀ −2×f _P , f ₀ −f _P , f ₀ , f ₀ +f _P. , F ₀ +2×f _P. In this example, as shown in FIG. 5A, the envelope of the combined power of the plurality of power components includes four peak groups. In this example, as shown in FIG. 5C, the high frequency power HF is composed of a peak group including the maximum peak among the four peak groups. The high frequency power HF may be composed of two or more power components. The frequencies of the two or more power components are set symmetrically with respect to the fundamental frequency f ₀ , and are set at intervals defined by the predetermined frequency f _P.

Hereinafter, a plasma processing apparatus according to another embodiment will be described with reference to FIGS. 6, 7, and 8. FIG. 6 is a schematic diagram of a plasma processing apparatus according to another exemplary embodiment. FIG. 7 is a diagram showing a configuration of a high frequency power supply and a bias power supply of a plasma processing apparatus according to another exemplary embodiment. FIG. 8 is another exemplary timing chart of high frequency power (HF), ion density (Ni), electron temperature (Te), and bias power (high frequency bias power LF).

The plasma processing apparatus 1B according to another embodiment includes a bias power supply 81B and a filter 83B instead of the bias power supply 81 and the filter 83. The plasma processing apparatus 1B further includes a matching box 82B. In other respects, the plasma processing apparatus 1B is configured similarly to the plasma processing apparatus 1.

The bias power source 81B is configured to generate a high frequency bias power LF as the bias power BP for attracting ions to the substrate support 14. The frequency of the high frequency bias power LF is the reciprocal of the period CP. The frequency of the high frequency bias power LF is lower than the fundamental frequency f ₀ . The frequency of the high frequency bias power LF is, for example, a frequency within the range of 400 kHz to 13.56 MHz. In one example, the frequency of the high frequency bias power LF is 400 kHz. In one embodiment, the frequency of the high frequency bias power LF can be the frequency f _P described above. The high frequency bias power LF is supplied to the lower electrode 18.

The bias power source 81B is electrically connected to the lower electrode 18 via the matching unit 82B. The matching device 82B has a matching circuit. The matching circuit of the matching device 82B is configured to match the load side (lower electrode side) impedance of the bias power supply 81B with the output impedance of the bias power supply 81B. A filter 83B may be provided between the matching unit 82B and the lower electrode 18. The filter 83B is configured to pass the high frequency bias power LF and reduce or block other signals to the bias power supply 81B.

As shown in FIG. 7, in one embodiment, the bias power supply 81B may include a signal generator 81Ba and an amplifier 81Bb. The signal generator 81Ba is configured to generate a high frequency signal having the same frequency as the frequency of the high frequency bias power LF. The high frequency signal generated by the signal generator 81Ba is input to the amplifier 81Bb. The amplifier 81Bb is configured to amplify the input high frequency signal and generate the high frequency bias power LF.

In the plasma processing apparatus 1B, as shown in FIG. 8, the high frequency power supply 61 outputs one or more pulses of the high frequency power HF in the first period P1 in which the high frequency bias power LF output from the bias power supply 81B has a positive voltage. It is configured to be supplied as PL. In the example shown in FIG. 8, one pulse PL of the high frequency power HF is supplied in the single first period P1.

In the plasma processing apparatus 1B, the high frequency power supply 61 is configured to stop the supply of the high frequency power HF in the second period P2 in which the high frequency bias power LF output from the bias power supply 81B has a negative voltage.

In the plasma processing apparatus 1B as well, similar to the plasma processing apparatus 1, the high frequency power supply 61 generates the high frequency power HF so that each pulse PL has a power level that gradually increases from the start time to the time when its peak appears. .. Similarly to the plasma processing apparatus 1, in the plasma processing apparatus 1B, the rising time of each pulse PL of the high frequency power HF can be set to a time longer than the minimum rising time of the pulse of the high frequency power that can be output from the high frequency power supply 61. ..

Ions in the plasma in the chamber 10 are accelerated toward the substrate W in the second period P2. As a result, the substrate W is etched in the second period P2. Therefore, in the second period P2, the reaction product is released from the substrate W. When the electron temperature of plasma is high, re-dissociation of reaction products occurs. The substance generated by the re-dissociation of the reaction product can be deposited on the substrate W. In the plasma processing apparatus 1B, since the high frequency power HF is not supplied during the second period P2, the electron temperature of plasma is low during the second period P2. Therefore, according to the plasma processing apparatus 1B, re-dissociation of reaction products is suppressed. When the re-dissociation of reaction products is suppressed, the formation of deposits on the substrate W is suppressed. As a result, reduction or blockage of the opening formed in the substrate W by plasma etching is suppressed.

In addition, in the first period P1, the high frequency power HF is supplied as one or more pulses PL. The power level of each pulse PL gradually rises to its peak. Therefore, the overshoot of the electron temperature is suppressed. As a result, according to the plasma processing apparatus 1B, excessive dissociation of gas is suppressed. Therefore, according to the plasma processing apparatus 1B, the substrate W can be etched at a relatively high etching rate.

In one embodiment, the controller 80 or another controller may control the bias power supply 81B to set the phase of the high frequency bias power LF. Specifically, the high frequency power supply 61 and the bias power supply 81B are synchronized with each other by a clock signal provided from the control unit 80 or another controller. The control unit 80 or another controller gives a signal for setting the phase of the high frequency bias power LF to the bias power supply 81B in order to set the phase difference between the high frequency power HF and the high frequency bias power LF. The bias power source 81B outputs the high frequency bias power LF at the given phase. According to this embodiment, it is possible to adjust the time difference TA between the time when the supply of the pulse PL ends and the time when the potential of the lower electrode 18 has a negative peak. Further, it becomes possible to adjust the time difference TB between the time when the potential of the lower electrode 18 has a negative peak and the time when the supply of the pulse PL is started.

Hereinafter, FIG. 9 will be referred to. FIG. 9 is yet another exemplary timing chart of the high frequency power (HF), the ion density (Ni), the electron temperature (Te), and the bias power (pulsed negative DC voltage BV). As shown in FIG. 9, also in another embodiment, the high frequency power supply 61 generates the high frequency power HF so that each pulse PL has a power level that gradually increases from the start time of the pulse PL to the time when its peak appears. To do. In yet another embodiment, the rising time of each pulse PL of the high frequency power HF can be set to a time longer than the minimum rising time of the pulse of the high frequency power that can be output from the high frequency power supply 61. In this embodiment, the high frequency power supply 61 may have a ramp-up circuit or a ramp-up function for adjusting the rising time of the rectangular pulse of the high-frequency power, that is, the lamp rising time. As shown in FIG. 9, in yet another embodiment, the fall time of each pulse PL generated by the high frequency power supply 61 may be shorter than the rise time of each pulse PL. For example, each pulse may switch from ON to OFF substantially instantaneously or continuously. Further, in the embodiment shown in FIG. 9, the high frequency bias power LF may be used as the bias power instead of the pulsed negative DC voltage BV.

Hereinafter, FIG. 10 will be referred to. FIG. 10 is yet another exemplary timing chart of the high frequency power (HF) and the bias power (pulse-shaped negative DC voltage BV). In yet another embodiment, as shown in FIG. 10, the high frequency power supply 61 may generate a plurality of pulses PL for plasma generation within the first period P1. Within the first period P1, the plurality of pulses PL are continuously or intermittently and sequentially supplied. According to this embodiment, the average value of the electron temperature of plasma in the first period P1 is reduced. Therefore, excessive dissociation of gas in the chamber 10 is further suppressed. In the embodiment shown in FIG. 10, the high frequency bias power LF may be used as the bias power instead of the pulsed DC voltage BV having the negative polarity.

Hereinafter, FIG. 11 will be referred to. FIG. 11 is a diagram showing a configuration of a high frequency power supply according to another exemplary embodiment. As shown in FIG. 11, in another embodiment, a high frequency power supply 61B may be used instead of the high frequency power supply 61. The high frequency power supply 61B has a power generator 61Bg and an output unit 61a. The power generator 61Bg is configured to generate the high frequency power HF. In the high frequency power supply 61B, the output unit 61a is configured to output the high frequency power HF generated by the power generator 61Bg.

The power generator 61Bg has a modulation signal generator 64B. The power generator 61Bg may further include an amplifier 65. The modulation signal generator 64B generates a modulation high frequency signal. The high frequency power HF may be a modulated high frequency signal generated by the modulation signal generator 64B. In this case, the amplifier 65 is unnecessary. Alternatively, the high frequency power HF may be generated by the modulated high frequency signal being amplified by the amplifier 65.

The modulation signal generator 64B may include a plurality of signal generators 911 to 91N, an adder 92, and a switching circuit 93. Here, “N” is an integer of 2 or more. The plurality of signal generators 911 to 91N are configured to respectively generate a plurality of high frequency signals. The frequencies of the plurality of high frequency signals are set symmetrically with respect to the fundamental frequency f ₀ . The frequencies of the plurality of high frequency signals are set at intervals of a predetermined frequency f _P.

The adder 92 is configured to add a plurality of high frequency signals from the plurality of signal generators 911 to 91N and generate a combined signal. The envelope of the composite signal has peaks that appear periodically at time intervals T _P. The switching circuit 93 is configured to generate a modulated high frequency signal from the combined signal. The modulated high-frequency signal has an amplitude level between a zero-cross area Z _{A of the} envelope immediately before the output time of each peak of the envelope of the composite signal and a zero-cross area Z _B of the envelope immediately after the output time. It is set to be zero in the period P _A excluding the period P _P in between. The high frequency power supply 61B can also generate the high frequency power HF, like the high frequency power supply 61. That is, the high frequency power supply 61B can also generate high frequency power pulses.

Although various exemplary embodiments have been described above, various additions, omissions, substitutions, and changes may be made without being limited to the exemplary embodiments described above. In addition, elements in different embodiments can be combined to form other embodiments.

In another embodiment, the plasma processing apparatus may be another type of plasma processing apparatus such as an inductively coupled plasma processing apparatus. In the inductively coupled plasma processing apparatus, the high frequency power HF is supplied to an antenna for generating inductively coupled plasma.

From the foregoing description, it is understood that various embodiments of the present disclosure are described herein for purposes of illustration and that various changes may be made without departing from the scope and spirit of the disclosure. Will. Therefore, the various embodiments disclosed herein are not intended to be limiting, the true scope and spirit of which is indicated by the appended claims.

DESCRIPTION OF SYMBOLS 1... Plasma processing apparatus, 10... Chamber, 61... High frequency power supply, 81... Bias power supply.

Claims (12)

A chamber,
A substrate support having a lower electrode and configured to support a substrate in the chamber;
A high frequency power supply configured to generate high frequency power to generate plasma from gas in the chamber;
A bias power supply that is electrically connected to the lower electrode and that is configured to generate a bias power for attracting ions to the substrate support;
Equipped with
The bias power supply is configured to periodically generate a pulsed negative DC voltage as the bias power,
The high frequency power supply supplies the high frequency power as one or more pulses during a first period in which the pulsed negative DC voltage is not applied to the lower electrode, and the pulsed negative DC voltage is supplied. Is configured to stop the supply of the high-frequency power in the second period in which is applied to the lower electrode,
The radio frequency power source generates the radio frequency power such that each of the one or more pulses has a power level that gradually increases from its start time to the time its peak appears.
Plasma processing equipment. The plasma processing apparatus of claim 1, further comprising a control unit configured to control the bias power supply to set a phase of a cycle of the pulsed negative DC voltage. The plasma processing apparatus according to claim 2, wherein the control unit is configured to further control the bias power supply so as to set the duration of the pulsed negative DC voltage. A chamber,
A substrate support having a lower electrode and configured to support a substrate in the chamber;
A high frequency power supply configured to generate high frequency power to generate plasma from gas in the chamber;
A bias power supply that is electrically connected to the lower electrode and that is configured to generate a bias power for attracting ions to the substrate support;
Equipped with
The bias power source is configured to generate high frequency bias power as the bias power,
The high frequency power supply supplies the high frequency power as one or more pulses during a first period in which the high frequency bias power output from the bias power supply has a positive voltage, and outputs the high frequency bias output from the bias power supply. It is configured to stop the supply of the high frequency power in a second period in which the power has a negative voltage,
The radio frequency power supply generates the radio frequency power such that each of the one or more pulses has a power level that gradually increases from its start time to the time its peak appears.
Plasma processing equipment. The plasma processing apparatus of claim 4, further comprising a controller configured to control the bias power supply to set a phase of the high frequency bias power. The plasma processing apparatus according to claim 1, wherein a rising time of each of the one or more pulses is longer than a minimum rising time of a pulse of high-frequency power that can be output from the high-frequency power supply. The high frequency power source,
A power generator configured to generate the high frequency power;
An output unit configured to output the high frequency power generated by the power generator;
The plasma processing apparatus according to claim 1, further comprising: The power generator is the high-frequency power including a plurality of power components each having a plurality of frequencies symmetrically set with respect to the fundamental frequency at intervals of a predetermined frequency, the envelope is the predetermined frequency or It has a peak that appears periodically at a time interval defined by a frequency that is a multiple of two or more of the predetermined frequency, and its power level is a zero-cross region of the envelope immediately before the output time point of each of the peaks. And is configured to generate the high frequency power, which is set to be zero in a period excluding a period between the zero crossing region of the envelope immediately after the output time point,
The plasma processing apparatus according to claim 7. The power generator is
A waveform data generator,
Quantizing the waveform data generated by the waveform data generation unit, a quantization unit configured to generate quantized data,
An inverse Fourier transform unit configured to apply an inverse Fourier transform to the quantized data to generate I data and Q data,
A modulation unit configured to modulate two reference high frequency signals whose phases are different from each other by 90° using the I data and the Q data to generate a modulated high frequency signal;
And is configured to generate the high frequency power from the modulated high frequency signal,
The plasma processing apparatus according to claim 7. The plasma processing apparatus of claim 9, wherein the power generator further comprises an amplifier configured to amplify the modulated high frequency signal to generate the high frequency power. 7. The plasma processing apparatus according to claim 1, wherein the high frequency power supply is configured to be able to adjust the rising time of each of the one or more pulses. The plasma processing apparatus according to claim 1, wherein the high frequency power supply is configured to sequentially supply a plurality of pulses as the one or more pulses in the first period.

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