JP2022075506A - Plasma treatment apparatus and plasma treatment method - Google Patents

Abstract

To provide a technology capable of controlling an energy of an ion colliding against a substrate, by a voltage pulse applied to a bias electrode.SOLUTION: A plasma treatment apparatus includes a chamber, a substrate supporting device, a plasma generation part, and a bias power source. The substrate supporting device includes a bias electrode, and is arranged in the chamber. The plasma generation part is configured so as to generate plasma from gas in the chamber. The bias power source is electrically connected to the bias electrode, and is configured to produce a sequence of multiple voltage pulses. Each of the multiple voltage pulses has a front edge period of transiting from a reference voltage level to a pulse voltage level and a rear edge period of transiting from the pulse voltage level to the reference voltage level. At least one of a time length of the front edge period or a time length of the rear edge period is longer than 0 second and 0.5μ seconds or less.SELECTED DRAWING: Figure 1

Description

An exemplary embodiment of the present disclosure relates to a plasma processing apparatus and a plasma processing method.

Plasma processing equipment is used in plasma processing of substrates. The plasma processing device includes a chamber and a substrate holding electrode. The substrate holding electrode is provided in the chamber. The substrate holding electrode holds the substrate mounted on its main surface. A type of such plasma processing apparatus is described in Japanese Patent Application Laid-Open No. 2009-187975 (hereinafter referred to as "Patent Document 1").

The plasma processing apparatus described in Patent Document 1 further includes a high frequency generator and a DC negative pulse generator. The high frequency generator applies a high frequency voltage to the substrate holding electrode. In the plasma processing apparatus described in Patent Document 1, the high frequency voltage is switched on and off alternately. Further, in the plasma processing apparatus described in Patent Document 1, a DC negative pulse voltage is applied from the DC negative pulse generator to the substrate holding electrode according to the timing of turning on and off the high frequency voltage.

Japanese Unexamined Patent Publication No. 2009-187975

The present disclosure provides a technique for controlling the energy of ions colliding with a substrate by a voltage pulse applied to a bias electrode.

In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing device includes a chamber, a substrate support, a plasma generator, and a bias power supply. The substrate support includes a bias electrode and is provided in the chamber. The plasma generator is configured to generate plasma from the gas in the chamber. The bias power supply is electrically connected to the bias electrode and is configured to generate a sequence of multiple voltage pulses applied to the bias electrode. Each of the plurality of voltage pulses has a leading edge period in which the reference voltage level transitions to the pulse voltage level and a trailing edge period in which the pulse voltage level transitions to the reference voltage level. At least one of the time length of the leading edge period and the time length of the trailing edge period is longer than 0 seconds and 0.5 μsec or less.

According to one exemplary embodiment, it is possible to control the energy of the ions colliding with the substrate by the voltage pulse applied to the bias electrode.

It is a figure which shows schematically the plasma processing apparatus which concerns on one exemplary Embodiment. It is a figure which shows an example of the waveform of the output voltage of the bias power source in the plasma processing apparatus which concerns on one exemplary embodiment. It is a figure which shows the bias power source in the plasma processing apparatus which concerns on one exemplary Embodiment. It is a flow chart of the plasma processing method which concerns on one exemplary embodiment. It is a graph which shows the result of the 1st simulation. It is a graph which shows the result of the 2nd simulation. It is a graph which shows the result of the 3rd simulation. It is a figure which shows another example of the waveform of the output voltage of the bias power source in the plasma processing apparatus which concerns on one exemplary embodiment.

Hereinafter, various exemplary embodiments will be described.

In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing device includes a chamber, a substrate support, a plasma generator, and a bias power supply. The substrate support includes a bias electrode and is provided in the chamber. The plasma generator is configured to generate plasma from the gas in the chamber. The bias power supply is electrically connected to the bias electrode and is configured to generate a sequence of multiple voltage pulses applied to the bias electrode. Each of the plurality of voltage pulses has a leading edge period in which the reference voltage level transitions to the pulse voltage level and a trailing edge period in which the pulse voltage level transitions to the reference voltage level. At least one of the time length of the leading edge period and the time length of the trailing edge period is longer than 0 seconds and 0.5 μsec or less.

When the pulse of the voltage applied to the bias electrode is a perfect rectangular pulse, it is possible to control the energy of the ions colliding with the substrate, but the cost for this is high. According to the negative voltage pulse having at least one of the leading edge period and the trailing edge period described above, it is possible to control the energy of the ions colliding with the substrate as in the case of using a perfect rectangular pulse.

In one exemplary embodiment, at least one of the time length of the leading edge period and the time length of the trailing edge period may be longer than 0 seconds and 0.25 μs or less. In one exemplary embodiment, at least one of the time length of the leading edge period and the time length of the trailing edge period may be 0.05 μsec or more.

In one exemplary embodiment, the pulse voltage level may be greater than or equal to −20 kV and less than or equal to −0.5 kV. In one exemplary embodiment, the reference voltage level may be 0V.

In one exemplary embodiment, the bias power supply may be configured to periodically apply a plurality of voltage pulses to the bias electrode.

In one exemplary embodiment, the bias power supply may include a DC power supply and a pulse unit. The pulse unit is provided between the DC power supply and the bias electrode. The pulse unit includes a first switching element, a second switching element, and an impedance circuit. The first switching element and the second switching element are connected in series between the positive electrode and the negative electrode of the DC power supply. The impedance circuit is connected between the node and the bias electrode between the first switching element and the second switching element.

In one exemplary embodiment, the plasma processing apparatus may further include a pulse controller configured to control the pulse unit. The pulse controller alternately performs the first control of closing the first switching element and opening the second switching element and the second control of opening the first switching element and closing the second switching element. It is configured.

In one exemplary embodiment, the impedance circuit may include an inductor and a resistance element connected in series between the node and the bias electrode.

In one exemplary embodiment, the plasma generator may include a high frequency power source.

In another exemplary embodiment, plasma treatment methods are provided. The plasma processing method includes a step of preparing a substrate on a substrate support in the chamber of the plasma processing apparatus. The plasma processing method further comprises the step of generating plasma in the chamber. The plasma processing method further comprises applying a sequence of multiple voltage pulses to the substrate support while the plasma is being generated in the chamber. Each of the plurality of voltage pulses has a leading edge period in which the reference voltage level transitions to the pulse voltage level and a trailing edge period in which the pulse voltage level transitions to the reference voltage level. At least one of the time length of the leading edge period and the time length of the trailing edge period is longer than 0 seconds and 0.5 μsec or less.

In yet another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a plasma generator, and a bias power supply. The substrate support includes a bias electrode and is provided in the chamber. The plasma generator is configured to generate plasma from the gas in the chamber. The bias power supply is electrically connected to the bias electrode and is configured to generate a sequence of multiple voltage pulses. Bias power supplies include DC power supplies and pulse units. The pulse unit is provided between the DC power supply and the bias electrode. The pulse unit includes a first switching element, a second switching element, and an impedance circuit. The first switching element and the second switching element are connected in series between the positive electrode and the negative electrode of the DC power supply. The impedance circuit is connected between the node and the bias electrode between the first switching element and the second switching element.

In one exemplary embodiment, the plasma processing apparatus may further include a pulse controller configured to control the pulse unit. The pulse controller alternately performs the first control of closing the first switching element and opening the second switching element and the second control of opening the first switching element and closing the second switching element. It is configured.

In one exemplary embodiment, the impedance circuit may include an inductor and a resistance element connected in series between the node and the bias electrode.

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

FIG. 1 is a diagram schematically showing a plasma processing apparatus according to one exemplary embodiment. The plasma processing device 1 shown in FIG. 1 is a capacitively coupled plasma processing device. The plasma processing device 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The central axis of the chamber 10 is the axis AX and extends in the vertical direction.

In one embodiment, the chamber 10 may include a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space 10s is provided in the chamber body 12. The chamber body 12 is made of, for example, aluminum. The chamber body 12 is electrically grounded. A plasma-resistant film may be formed on the inner wall surface of the chamber body 12, that is, the wall surface defining the internal space 10s. This film can be a ceramic film, such as a film formed by anodizing or a film formed from yttrium oxide.

The chamber body 12 may provide a passage 12p on its side wall. The substrate W passes through the passage 12p when being conveyed between the internal space 10s and the outside of the chamber 10. A gate valve 12g is provided along the side wall of the chamber body 12 for opening and closing the passage 12p.

The plasma processing device 1 further includes a substrate support 16. The substrate support 16 is configured to support the substrate W placed on the substrate support 16 in the chamber 10. The substrate W has a substantially disk shape. The substrate support 16 may be supported by the support 15. The support 15 extends upward from the bottom of the chamber body 12. The support 15 has a substantially cylindrical shape. The support 15 is formed of an insulating material such as quartz.

The substrate support 16 has a lower electrode 18. The substrate support 16 may further include an electrostatic chuck 20. The substrate support 16 may further include an electrode plate 19. The electrode plate 19 is made of a conductive material such as aluminum and has a substantially disk shape. The lower electrode 18 is provided on the electrode plate 19. The lower electrode 18 is formed of a conductive material such as aluminum and has a substantially disk shape. The lower electrode 18 is electrically connected to the electrode plate 19. The central axis of the lower electrode 18 and the electrode plate 19 substantially coincides with the axis AX.

The lower electrode 18 may provide a flow path 18f therein. The flow path 18f is a flow path for the heat exchange medium. As the heat exchange medium, for example, a refrigerant is used. The flow path 18f receives a heat exchange medium supplied from a supply device (for example, a chiller unit) via a pipe 23a. The feeding device is provided outside the chamber 10. The heat exchange medium from the supply device flows through the flow path 18f and is returned to the supply device via the pipe 23b.

The electrostatic chuck 20 is provided on the lower electrode 18. When the substrate W is processed in the internal space 10s, the substrate W is placed on the electrostatic chuck 20 so that its center is located on the axis AX. The electrostatic chuck 20 is configured to hold the substrate. The electrostatic chuck 20 has a main body and an electrode (chuck electrode). The main body of the electrostatic chuck 20 is formed of a dielectric such as aluminum oxide or aluminum nitride. The main body of the electrostatic chuck 20 has a substantially disk shape. The central axis of the electrostatic chuck 20 substantially coincides with the axis AX.

The electrodes of the electrostatic chuck 20 are provided in the main body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is a film formed of a conductor. A DC power supply is electrically connected to the electrodes of the electrostatic chuck 20. When a DC voltage is applied from the DC power supply to the electrodes of the electrostatic chuck 20, electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The substrate W is attracted to the electrostatic chuck 20 by the generated electrostatic attraction and is held by the electrostatic chuck 20.

The substrate support 16 may further support the edge ring ER mounted on it. The edge ring ER has a ring shape and is formed of, for example, silicon or silicon carbide. The edge ring ER is mounted on the substrate support 16 so that its central axis is located on the axis AX. In one embodiment, the edge ring ER may be partially mounted on the electrostatic chuck 20. The substrate W is arranged on the electrostatic chuck 20 and in a region surrounded by the edge ring ER.

The plasma processing apparatus 1 may further include a gas supply line 25. The gas supply line 25 supplies a heat transfer gas from the gas supply mechanism, for example, He gas, to the gap between the upper surface of the electrostatic chuck 20 and the back surface (lower surface) of the substrate W.

The plasma processing device 1 may further include a cylindrical portion 28 and an insulating portion 29. The tubular portion 28 extends upward from the bottom of the chamber body 12. The tubular portion 28 extends along the outer circumference of the support 15. The tubular portion 28 is formed of a conductive material and has a substantially cylindrical shape. The tubular portion 28 is electrically grounded. The insulating portion 29 is provided on the tubular portion 28. The insulating portion 29 is formed of an insulating material. The insulating portion 29 is made of a ceramic such as quartz. The insulating portion 29 has a substantially cylindrical shape. The insulating portion 29 extends along the outer circumference of the electrode plate 19, the outer circumference of the lower electrode 18, and the outer circumference of the electrostatic chuck 20.

The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the substrate support 16. The upper electrode 30 closes the upper opening of the chamber body 12 together with the member 32. The member 32 is made of an insulating material. The upper electrode 30 is supported on the upper part of the chamber body 12 via the member 32.

The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 defines the internal space 10s. A plurality of gas holes 34a are formed in the top plate 34. The plurality of gas holes 34a penetrate the top plate 34 in the plate thickness direction (vertical direction). The top plate 34 is made of, for example, silicon. Alternatively, the top plate 34 may have a structure in which a plasma resistant film is provided on the surface of an aluminum member. This film can be a ceramic film, such as a film formed by anodizing or a film formed from yttrium oxide.

The support 36 supports the top plate 34 in a detachable manner. The support 36 is made of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support 36. A 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 holes 34a, respectively. A gas introduction port 36c is formed on the support 36. The gas introduction port 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas introduction port 36c.

The 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, the valve group 41, the flow rate controller group 42, and the valve group 43 constitute a gas supply unit. 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 valves (for example, an on-off valve). The flow rate controller group 42 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers in 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 the gas supply pipe 38 via the corresponding valve of the valve group 41, the corresponding flow rate controller of the flow rate controller group 42, and the corresponding valve of the valve group 43. It is connected. The plasma processing apparatus 1 can supply gas from one or more gas sources selected from a plurality of gas sources of the gas source group 40 to the internal space 10s at an individually adjusted flow rate. ..

The plasma processing device 1 may further include a baffle member 48. The baffle member 48 is provided between the tubular portion 28 and the side wall of the chamber body 12. The baffle member 48 can be a plate-shaped member. The baffle member 48 may be configured, for example, by coating an aluminum plate with a ceramic such as yttrium oxide. The baffle member 48 provides a plurality of through holes. Below the baffle member 48, the exhaust pipe 52 is connected to the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust pipe 52. The exhaust device 50 has a pressure controller such as an automatic pressure control valve and a vacuum pump such as a turbo molecular pump, and can reduce the pressure in the internal space 10s.

The plasma processing device 1 further includes a high frequency power supply 61. The high frequency power supply 61 is a power supply that generates high frequency power for plasma generation. The high frequency power supply 61 constitutes the plasma generation unit of one embodiment. The frequency of the high frequency power may be a frequency in the range of 27 MHz to 100 MHz, for example, 40 MHz or 60 MHz. The high frequency power supply 61 is connected to the lower electrode 18 via the matching unit 61m and the electrode plate 19. The matching device 61m has a matching circuit for matching the impedance on the load side (lower electrode 18 side) of the high frequency power supply 61 with the output impedance of the high frequency power supply 61. The high frequency power supply 61 does not have to be electrically connected to the lower electrode 18, and may be connected to the upper electrode 30 via the matching unit 61m.

In the plasma processing apparatus 1, gas is supplied from the gas supply unit to the internal space 10s. Then, the gas is excited in the internal space 10s by supplying the high frequency power from the high frequency power supply 61. As a result, plasma is generated in the internal space 10s. The substrate W is treated with chemical species such as ions and / or radicals from the plasma.

The plasma processing device 1 further includes a bias power supply 70. The bias power supply 70 is electrically connected to the bias electrode. In the example shown in FIG. 1, the lower electrode 18 is used as a bias electrode, and the bias power supply 70 is electrically connected to the lower electrode 18. Hereinafter, FIG. 2 will be referred to together with FIG. FIG. 2 is a diagram showing an example of the waveform of the output voltage of the bias power supply in the plasma processing apparatus according to one exemplary embodiment. The bias power supply 70 is configured to generate a sequence of a plurality of voltage pulses NP as shown in FIG. The bias power supply 70 is configured to apply a sequence of a plurality of voltage pulses NP to the bias electrode (in one example, the lower electrode 18). In one embodiment, the bias power source 70 is configured to periodically apply a voltage pulse NP to the bias electrode (in one example, the lower electrode 18). The time interval (ie, period) at which the voltage pulse NP is applied to the bias electrode has a time length that is the reciprocal of the bias frequency. The bias frequency that defines the period in which the voltage pulse NP is applied to the bias electrode can be a frequency of 1 kHz or more and 27 MHz or less, for example, 400 kHz.

In the plasma processing apparatus 1, the energy of ions colliding with the substrate W from the plasma is adjusted according to the magnitude of the absolute value of the negative potential of the substrate set in response to the voltage pulse NP applied to the bias electrode. Will be done. In one embodiment, each of the plurality of voltage pulse NPs may be a negative voltage pulse. In this case, the energy of the ions colliding with the substrate W from the plasma is adjusted according to the magnitude of the absolute value of the voltage level of the voltage pulse NP.

As shown in FIG. 2, the voltage pulse NP is a pulse having a leading edge LE and a trailing edge TE. The voltage level of the voltage pulse NP changes from the reference voltage level LV to the pulse voltage level NV at the leading edge LE. The voltage level of the voltage pulse NP changes from the pulse voltage level NV to the reference voltage level LV at the trailing edge TE. The pulse voltage level NV is the voltage level (eg, negative voltage level) of the voltage pulse NP in the steady state. When the voltage pulse NP does not have a steady state such as a triangular wave, the pulse voltage level NV may be a negative voltage level having the highest absolute value in the voltage pulse NP. The pulse voltage level NV may be −20 kV or higher and −0.5 kV or lower. That is, the absolute value of the pulse voltage level NV may be 0.5 kV or more and 20 kV or less. The reference voltage level LV is the level of the output voltage of the bias power supply 70 when the voltage pulse NP is not output. The reference voltage level LV may be 0V. The reference voltage level LV may be a negative voltage level having an absolute value smaller than the absolute value of the pulse voltage level NV. Alternatively, the reference voltage level LV may be a positive voltage level.

The starting edge LE start time point is defined as the output start time point of the voltage pulse NP by the bias power supply 70. The end point of the leading edge LE is defined as the time of occurrence of an inflection in which the output voltage of the bias power supply 70 changes from the waveform of the leading edge LE to the waveform immediately after the leading edge LE (waveform of the pulse voltage level NV). When the voltage pulse NP does not have a steady state like a triangular wave, the end time of the leading edge LE is the time when a negative voltage having the maximum absolute value is generated in the voltage pulse NP. good.

Further, the start time of the trailing edge TE is defined as the time of occurrence of an inflection point in which the output voltage of the bias power supply 70 changes from the waveform immediately before the trailing edge TE (the waveform of the pulse voltage level NV) to the waveform of the trailing edge TE. To. When the voltage pulse NP does not have a steady state like a triangular wave, the starting edge TE starts even when a negative voltage having the maximum absolute value is generated in the voltage pulse NP. good. The end point of the trailing edge TE is defined as the end point of output of the voltage pulse NP by the bias power supply 70.

In the voltage pulse NP output by the bias power supply 70, at least one of the time length of the leading edge LE period (that is, the leading edge period TLE) and the time length of the trailing edge TE period (that is, the trailing edge period TTE) is , Longer than 0 seconds and 0.5 μsec or less. In one embodiment, at least one of the time length of the leading edge period TLE and the time length of the trailing edge period TTE may be longer than 0 seconds and 0.25 μs or less. In one embodiment, at least one of the time length of the leading edge period TLE and the time length of the trailing edge period TTE may be 0.05 μsec or more. In one embodiment, in the voltage pulse NP output by the bias power supply 70, each of the time length of the leading edge period TLE and the time length of the trailing edge period TTE is 0.05 μsec or more and 0.5 μsec or less. There may be. Further, the absolute value of the slope of the voltage change of the front edge LE is 1 kV / μsec (= | −0.5 kV / 0.5 μsec |) or more, 400 kV / μsec (= | −20 kV / 0.05 μm). Seconds |) may be less than or equal to. Further, the slope of the time change of the voltage of the trailing edge TE may be 1 kV / μsec or more and 400 kV / μsec or less.

The plasma processing device 1 may further include a control unit MC. The control unit MC is a computer including a processor, a storage device, an input device, a display device, and the like, and controls each unit of the plasma processing device 1. Specifically, the control unit MC executes a control program stored in the storage device and controls each unit of the plasma processing device 1 based on the recipe data stored in the storage device. Under the control of the control unit MC, the process specified by the recipe data is executed in the plasma processing apparatus 1. The plasma processing method according to the exemplary embodiment described later can be executed in the plasma processing device 1 by controlling each part of the plasma processing device 1 by the control unit MC.

Hereinafter, FIG. 3 will be referred to. FIG. 3 is a diagram showing a bias power supply in the plasma processing apparatus according to one exemplary embodiment. As shown in FIGS. 1 and 3, in one embodiment, the bias power supply 70 may be connected to the bias electrode (in one example, the lower electrode 18) via the filter 70f. The filter 70f cuts off or reduces high frequency power towards the bias power source 70. In one embodiment, the filter 70f may include an inductor 70fa and a capacitor 70fb. The inductor 70fa is connected between the bias electrode (lower electrode 18 in the example of FIG. 1) and the bias power supply 70 (or its output end 72). The capacitor 70fb is connected between the node and ground between the bias power supply 70 (or its output end 72) and the inductor 70fa.

As shown in FIG. 3, in one embodiment, the bias power supply 70 may include a DC power supply 71 and a pulse unit 73. The bias power supply 70 may further include an output terminal 72 and a pulse controller 74. The DC power supply 71 is a power supply that generates a DC voltage. The DC voltage generated by the DC power supply 71 may be a negative DC voltage. The DC power supply 71 may be a variable DC power supply. The DC power supply 71 may be controlled by the control unit MC. In the bias power supply 70, the voltage pulse NP is output from the output terminal 72.

The pulse unit 73 is provided between the DC power supply 71 and the output terminal 72 (or the bias electrode). The pulse unit 73 is configured to generate a voltage pulse NP from the DC voltage generated by the DC power supply 71. The pulse unit 73 includes a first switching element 731, a second switching element 732, and an impedance circuit 76. The pulse unit 73 may further include a capacitor 733, a diode 734, and a diode 735.

The first switching element 731 and the second switching element 732 are connected in series between the positive electrode and the negative electrode of the DC power supply 71. Each of the first switching element 731 and the second switching element 732 includes a first and second terminal, and a control terminal. The first terminal of the first switching element 731 is connected to the positive electrode of the DC power supply 71. The second terminal of the first switching element 731 is connected to the first terminal of the second switching element 732. The second terminal of the second switching element 732 is connected to the negative electrode of the DC power supply 71. Each of the first switching element 731 and the second switching element 732 makes its first terminal and the second terminal conductive to each other when it is closed by the voltage applied to its control terminal. On the other hand, each of the first switching element 731 and the second switching element 732 cuts off the conduction between the first terminal and the second terminal when it is opened by the voltage applied to the control terminal. do.

The capacitor 733 is connected in parallel between the positive electrode and the negative electrode of the DC power supply 71 with a series circuit including the first switching element 731 and the second switching element 732. The cathode of the diode 734 is connected to the positive electrode of the DC power supply 71 and the first terminal of the first switching element 731. The anode of the diode 734 and the cathode of the diode 735 are connected to the node 73b. The node 73b is connected to the node 73a between the first switching element 731 and the second switching element 732. The anode of the diode 735 is connected to the negative electrode of the DC power supply 71 and the second terminal of the second switching element 732.

The impedance circuit 75 is connected between the node 73a (or the node 73b) and the output end 72 (or the bias electrode). The impedance circuit 75 may include an inductor 751 and a resistance element 752 in one embodiment. The inductor 751 and the resistance element 752 are connected in series between the node 73a (or the node 73b) and the output end 72 (or the bias electrode). The resistance element 752 may have a small resistance value of about several Ω.

The pulse controller 74 is configured to control the pulse unit 73. The pulse controller 74 may include a programmable processor. The pulse controller 74 is configured to alternately perform the first control and the second control. In the first control, the pulse controller 74 is set to the control terminal of the first switching element 731 and the control terminal of the second switching element 732 so as to close the first switching element 731 and open the second switching element 732. Gives a control signal. As a result of the first control, the output terminal 72 is connected to the positive electrode of the DC power supply 71. In the second control, the pulse controller 74 sets the control terminal of the first switching element 731 and the control terminal of the second switching element 732 so as to open the first switching element 731 and close the second switching element 732. Gives a control signal. As a result of the second control, the output terminal 72 is connected to the negative electrode of the DC power supply 71.

The frequency that defines the period in which the voltage pulse NP is applied to the bias electrode (in one example, the lower electrode 18), that is, the bias frequency, may be designated by the control unit MC to the pulse controller 74. The ratio occupied by the time length of the voltage pulse NP in the cycle, that is, the duty ratio (%) can also be specified to the pulse controller 74 by the control unit MC. The pulse controller 74 alternately executes the first control and the second control so as to generate the voltage pulse NP periodically in a cycle having a time length of the reciprocal of the specified frequency (that is, a time interval). Further, the pulse controller 74 adjusts the time lengths of the first control and the second control according to the designated duty ratio. According to such a bias power supply 70, as shown in FIG. 2, the voltage pulse NP can be periodically applied to the bias electrode (in one example, the lower electrode 18).

When the voltage pulse NP applied to the bias electrode is a perfect rectangular pulse, it is possible to control the energy of the ions colliding with the substrate W, but the cost for this is high. According to the voltage pulse NP having at least one of the leading edge period TLE and the trailing edge period TTE described above, it is possible to control the energy of the ions colliding with the substrate W as in the case of using a perfect rectangular pulse. .. When each of the time length of the leading edge period TLE and the time length of the trailing edge period TTE is 0.05 seconds or more, ringing in the voltage pulse NP can be suppressed or reduced.

Hereinafter, the plasma processing method according to one exemplary embodiment will be described with reference to FIG. 4, taking the case of being applied in the plasma processing apparatus 1 shown in FIG. 1 as an example. FIG. 4 is a flow chart of the plasma processing method according to one exemplary embodiment.

The plasma processing method shown in FIG. 4 (hereinafter referred to as “method MT”) is started in step STa. In the process STa, the substrate W is prepared. The substrate W is placed on the substrate support 16 in the chamber 10 of the plasma processing apparatus 1.

In the subsequent step STb, plasma is generated in the chamber 10. In the step STb, gas is supplied into the chamber from the gas supply unit. In step STb, the exhaust device 50 adjusts the pressure of the gas in the chamber 10 to the specified pressure. In the step STb, the plasma generation unit generates plasma from the gas in the chamber 10. In the plasma processing apparatus 1, high-frequency power is supplied from the high-frequency power source 61 in order to generate plasma. In the process STb, the control unit MC controls the gas supply unit, the exhaust device 50, and the plasma generation unit (high frequency power supply 61).

Subsequent step STc is performed in the state where plasma is generated in the chamber 10 in step STb. In the step STc, a sequence of a plurality of voltage pulses NP is applied from the bias power supply 70 to the bias electrode (in one example, the lower electrode 18). At least one of the time length of the leading edge period TLE and the time length of the trailing edge period TTE of the voltage pulse NP is longer than 0 seconds and 0.5 μsec or less, as described above. In one embodiment, at least one of the time length of the leading edge period TLE and the time length of the trailing edge period TTE may be longer than 0 seconds and 0.25 μs or less. In one embodiment, at least one of the time length of the leading edge period TLE and the time length of the trailing edge period TTE may be 0.05 μsec or more. In one embodiment, in the voltage pulse NP output by the bias power supply 70, each of the time length of the leading edge period TLE and the time length of the trailing edge period TTE is 0.05 μsec or more and 0.5 μsec or less. There may be. In the process STc, the bias power supply 70 can be controlled by the control unit MC.

Hereinafter, the simulation performed for the evaluation of the plasma processing apparatus 1 will be described.

(First simulation)

In the first simulation, the energy distribution (IED) of the ions colliding with the substrate was obtained while changing the time length of the leading edge period TLE of the voltage pulse NP applied to the lower electrode 18. The bias frequency defining the period for applying the voltage pulse NP to the lower electrode 18 was 400 kHz, and the duty ratio of the voltage pulse NP was 50%. The time lengths of the leading edge period TLE were 0 μs, 0.25 μs, 0.5 μs, 0.75 μs, 1 μs, and 1.25 μs. When the time length of the leading edge period TLE is 0 μs, the waveform of the voltage pulse NP is a perfect rectangular wave. Further, for reference, the energy distribution (IED) of the ions colliding with the substrate was obtained when the lower electrode 18 was supplied with the high frequency bias power having a frequency of 400 kHz instead of the voltage pulse NP.

FIG. 5 shows the result of the first simulation. As shown in FIG. 5, it was confirmed that the ion energy tends to decrease as the time length of the leading edge period TLE increases. However, if the time length of the front edge period TLE is 0.5 μs or less, it is possible to collide the substrate with ions having almost the same energy as the energy of the ions colliding with the substrate when a perfect square wave is used. It was confirmed that. Further, the peak of the IED that collides with the substrate when the time length of the leading edge period TLE is 0.5 μs or less is larger than the peak of the IED that collides with the substrate when high frequency bias power (RF 400 kHz in FIG. 5) is supplied. Was confirmed to be considerably high.

(Second simulation)

In the second simulation, the distribution of the angle of the ions with respect to the substrate (IAD) when the ions collide with the substrate was obtained while changing the time length of the leading edge period TLE of the voltage pulse NP applied to the lower electrode 18. The bias frequency defining the period for applying the voltage pulse NP to the lower electrode 18 was 400 kHz, and the duty ratio of the voltage pulse NP was 50%. The time lengths of the leading edge period TLE were 0 μs, 0.25 μs, 0.5 μs, 0.75 μs, 1 μs, and 1.25 μs. Further, for reference, the distribution (IAD) of the angle of the ions with respect to the substrate when the ions collide with the substrate when the low frequency bias power having a frequency of 400 kHz is supplied to the lower electrode 18 instead of the voltage pulse NP was obtained. ..

FIG. 6 shows the result of the second simulation. FIG. 6 shows that the ions collide perpendicularly with the substrate when the angle is 0 °. As shown in FIG. 6, it was confirmed that the distribution of the angles at which the ions collide with the substrate W tends to increase as the time length of the leading edge period TLE increases. However, when the time length of the leading edge period TLE was 0.5 μs or less, an IAD similar to the IAD when a perfect square wave was used was obtained. That is, it was confirmed that when the time length of the leading edge period TLE was 0.5 μs or less, the ions collided with the substrate substantially vertically and the distribution of the angles of collision of the ions with respect to the substrate was narrow.

(Third simulation)

In the third simulation, the distribution of the energy of the ions colliding with the substrate while changing the level of the voltage (voltage between the leading edge LE and the trailing edge TE) in the steady state of the voltage pulse NP applied to the lower electrode 18. (IED) was requested. The voltage levels of the voltage pulse NP applied to the lower electrode 18 in the steady state were −450V, −900V, and -1350V. The bias frequency defining the period for applying the voltage pulse NP to the lower electrode 18 was 400 kHz, and the duty ratio of the voltage pulse NP was 20%. The time length of each of the leading edge period TLE and the trailing edge period TTE was 0.3 μs.

FIG. 7 shows the result of the third simulation. As shown in FIG. 7, the peak ion energy in the IED may increase depending on the magnitude of the absolute value of the voltage level in the steady state of the voltage pulse NP applied to the lower electrode 18, that is, the bias electrode. confirmed. Therefore, it was confirmed that it is possible to control the energy of the ions colliding with the substrate by controlling the voltage level of the voltage pulse NP applied to the lower electrode 18 in the steady state.

Although various exemplary embodiments have been described above, various additions, omissions, substitutions, and changes may be made without being limited to the above-mentioned exemplary embodiments. It is also possible to combine elements in different embodiments to form other embodiments.

In another embodiment, a positive voltage pulse may be applied to the bias electrode. Even when a positive voltage pulse is applied to the bias electrode, it is possible to control the energy of ions colliding with the substrate by the potential difference between the potential of the bias electrode and the plasma potential.

FIG. 8 is a diagram showing another example of the waveform of the output voltage of the bias power supply in the plasma processing apparatus according to one exemplary embodiment. As shown in FIG. 8, each of the plurality of voltage pulse NPs has at least one difference between the reference voltage level LV and the pulse voltage level NV during at least one of the leading edge period TLE and the trailing edge period TTE. It may transition to a voltage level. In the front edge period TLE, the pulse unit 73 first floats the potential of the bias electrode for a certain period before the voltage of each of the plurality of voltage pulse NPs changes from the reference voltage level LV to the pulse voltage level NV. The switching element 731 and the second switching element 732 may be opened. In the trailing edge period TTE, the pulse unit 73 first floats the potential of the bias electrode for a certain period of time before the voltage of each of the plurality of voltage pulses NP changes from the pulse voltage level NV to the reference voltage level LV. The switching element 731 and the second switching element 732 may be opened.

In another embodiment, the plasma processing device provided with the bias power supply 70 may be another type of plasma processing device instead of the capacitively coupled plasma processing device. The other type of plasma processing apparatus may be an induction coupling type plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, a plasma processing apparatus that generates plasma using a surface wave such as a microwave, or the like. In the plasma processing methods according to various exemplary embodiments, such other types of plasma processing devices may be used.

Further, in another embodiment, the lower electrode 18 may not be used as a bias electrode. In this case, the substrate support 16 may have one or more bias electrodes provided in the main body of the electrostatic chuck 20.

In one embodiment, at least one bias electrode may be provided in the first region of the electrostatic chuck 20 on which the substrate is placed. At least one bias electrode may be provided between the chuck electrode and the lower electrode 18 in the first region. Alternatively, at least one bias electrode may be the chuck electrode of the electrostatic chuck 20. The bias power supply 70 is electrically connected to at least one bias electrode and is configured to apply a voltage pulse NP to the at least one bias electrode.

The at least one bias electrode may also extend within the second region of the electrostatic chuck 20 on which the edge ring ER is placed. Alternatively, the one or more bias electrodes may include at least one other bias electrode provided in the second region. The at least one other bias electrode may be another chuck electrode provided to generate electrostatic attraction to hold the edge ring ER, or it may be provided separately from the other chuck electrode. It may be an electrode. The other chuck electrode may be a chuck electrode constituting a unipolar type electrostatic chuck, or may be a chuck electrode constituting a bipolar type electrostatic chuck. The bias power supply 70 may be electrically connected to at least one other bias electrode in the second region in addition to the at least one bias electrode in the first region.

From the above description, it is understood that the various embodiments of the present disclosure are described herein for purposes of explanation and that various modifications can be made without departing from the scope and gist of the present disclosure. Will. Accordingly, the various embodiments disclosed herein are not intended to be limiting, and the true scope and gist is set forth by the appended claims.

1 ... Plasma processing device, 10 ... Chamber, 16 ... Board support, 18 ... Lower electrode, 61 ... High frequency power supply, 70 ... Bias power supply.

The pulse unit 73 is provided between the DC power supply 71 and the output terminal 72 (or the bias electrode). The pulse unit 73 is configured to generate a voltage pulse NP from the DC voltage generated by the DC power supply 71. The pulse unit 73 includes a first switching element 731, a second switching element 732, and an impedance circuit 75 . The pulse unit 73 may further include a capacitor 733, a diode 734, and a diode 735.

When the voltage pulse NP applied to the bias electrode is a perfect rectangular pulse, it is possible to control the energy of the ions colliding with the substrate W, but the cost for this is high. According to the voltage pulse NP having at least one of the leading edge period TLE and the trailing edge period TTE described above, it is possible to control the energy of the ions colliding with the substrate W as in the case of using a perfect rectangular pulse. .. When each of the time length of the leading edge period TLE and the time length of the trailing edge period TTE is 0.05 μsec or more, ringing in the voltage pulse NP can be suppressed or reduced.

Claims (16)

With the chamber
A substrate support including a bias electrode and provided in the chamber,
A plasma generator configured to generate plasma from gas in the chamber,
A bias power supply that is electrically connected to the bias electrode and is configured to generate a sequence of multiple voltage pulses applied to the bias electrode.
Equipped with
Each of the plurality of voltage pulses has a leading edge period for transitioning from the reference voltage level to the pulse voltage level and a trailing edge period for transitioning from the pulse voltage level to the reference voltage level, and the time of the leading edge period. At least one of the length and the time length of the trailing edge period is longer than 0 seconds and 0.5 μs or less.
Plasma processing equipment. The plasma processing apparatus according to claim 1, wherein at least one of the time length of the leading edge period and the time length of the trailing edge period is longer than 0 seconds and 0.25 μs or less. The plasma processing apparatus according to claim 1 or 2, wherein at least one of the time length of the leading edge period and the time length of the trailing edge period is 0.05 μsec or more. Each of the plurality of voltage pulses transitions to at least one different voltage level between the reference voltage level and the pulse voltage level during at least one of the leading edge period and the trailing edge period. Item 6. The plasma processing apparatus according to any one of Items 1 to 3. The plasma processing apparatus according to any one of claims 1 to 4, wherein each of the plurality of voltage pulses is a negative voltage pulse. The plasma processing apparatus according to claim 5, wherein the pulse voltage level is −20 kV or higher and −0.5 kV or lower. The plasma processing apparatus according to claim 5 or 6, wherein the reference voltage level is 0V. The plasma processing apparatus according to any one of claims 1 to 7, wherein the bias power supply is configured to periodically apply the plurality of voltage pulses to the bias electrode. The bias power supply is
DC power supply and
A pulse unit provided between the DC power supply and the bias electrode,
Including
The pulse unit is
A first switching element and a second switching element connected in series between the positive electrode and the negative electrode of the DC power supply,
An impedance circuit connected between the node between the first switching element and the second switching element and the bias electrode, and
including,
The plasma processing apparatus according to any one of claims 1 to 8. Further equipped with a pulse controller configured to control the pulse unit,
The pulse controller has a first control that closes the first switching element and opens the second switching element, and a second control that opens the first switching element and closes the second switching element. Configured to alternate,
The plasma processing apparatus according to claim 9. The plasma processing apparatus according to claim 9 or 10, wherein the impedance circuit includes an inductor and a resistance element connected in series between the node and the bias electrode. The plasma processing apparatus according to any one of claims 1 to 11, wherein the plasma generation unit includes a high-frequency power supply. The process of preparing the board on the board support in the chamber of the plasma processing device,
The process of generating plasma in the chamber and
A step of applying a sequence of a plurality of voltage pulses to the substrate support while the plasma is being generated in the chamber,
Including
Each of the plurality of voltage pulses has a leading edge period for transitioning from the reference voltage level to the pulse voltage level and a trailing edge period for transitioning from the pulse voltage level to the reference voltage level, and the time of the leading edge period. At least one of the length and the time length of the trailing edge period is longer than 0 seconds and 0.5 μs or less.
Plasma processing method. With the chamber
A substrate support including a bias electrode and provided in the chamber,
A plasma generator configured to generate plasma from gas in the chamber,
A bias power supply that is electrically connected to the bias electrode and is configured to generate a sequence of multiple voltage pulses.
Equipped with
The bias power supply is
DC power supply and
A pulse unit provided between the DC power supply and the bias electrode,
Including
The pulse unit is
A first switching element and a second switching element connected in series between the positive electrode and the negative electrode of the DC power supply,
An impedance circuit connected between the node between the first switching element and the second switching element and the bias electrode, and
including,
Plasma processing equipment. Further equipped with a pulse controller configured to control the pulse unit,
The pulse controller has a first control that closes the first switching element and opens the second switching element, and a second control that opens the first switching element and closes the second switching element. Configured to alternate,
The plasma processing apparatus according to claim 14. The plasma processing apparatus according to claim 14, wherein the impedance circuit includes an inductor and a resistance element connected in series between the node and the bias electrode.

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