Plasma treatment apparatus and plasma treatment method

Abstract

The object of this invention is to provide a technique for suppressing the power of reflected high-frequency electrical waves during plasma ignition. To achieve this object, the plasma processing apparatus of this invention includes: a processing chamber, a substrate support, a high-frequency power supply, and a bias power supply. The substrate support includes electrodes and is disposed within the processing chamber. The high-frequency power supply supplies high-frequency electrical power for generating plasma from gas within the processing chamber. The bias power supply is electrically connected to the electrodes of the substrate support. The high-frequency power supply supplies high-frequency electrical power during the ignition period when the plasma is ignited within the processing chamber. During the ignition period, the bias power supply sequentially applies a plurality of bias pulses, each a negative voltage, to the electrodes of the substrate support, and progressively increases the absolute value of the voltage level of the plurality of bias pulses.

Description

[Technical Field]

[0001] The exemplary embodiments of the present invention relate to a plasma treatment apparatus and a plasma treatment method. [Previous Technology]

[0002] A plasma processing apparatus is used for substrate processing. One type of plasma processing apparatus includes a processing chamber, a substrate support, a high-frequency power supply, and a bias power supply. The substrate support includes electrodes and is disposed within the processing chamber. The high-frequency power supply provides high-frequency electricity to generate plasma from gas within the processing chamber. The bias power supply imparts bias energy to the electrodes of the substrate support to attract ions to the substrate. Patent Document 1 below describes a technique using a pulse of negative DC voltage as bias energy. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-036658 [Summary of the Invention]

[0004] [The problem the invention aims to solve]

[0005] This invention provides a technique for suppressing the power of reflected high-frequency electrical waves during plasma ignition. [Means of the Problem]

[0006] In one illustrated embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes: a processing chamber, a substrate support, a high-frequency power supply, and a bias power supply. The substrate support includes electrodes and is disposed within the processing chamber. The high-frequency power supply supplies high-frequency power for generating plasma from gas within the processing chamber. The bias power supply is electrically connected to the electrodes of the substrate support. The high-frequency power supply supplies high-frequency power during the ignition period of igniting the plasma within the processing chamber. During the ignition period, the bias power supply sequentially applies a plurality of bias pulses, each a negative voltage, to the electrodes of the substrate support, and progressively or gradually increases the absolute value of the voltage level of the plurality of bias pulses. [Effects of the Invention]

[0007] According to an example embodiment, the power of the reflected wave of high-frequency electricity can be suppressed during the ignition of the plasma.

Implementation Method

[0009] The following describes various exemplary implementations.

[0010] In one illustrated embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes: a processing chamber, a substrate support, a high-frequency power supply, and a bias power supply. The substrate support includes electrodes and is disposed within the processing chamber. The high-frequency power supply supplies high-frequency power for generating plasma from gas within the processing chamber. The bias power supply is electrically connected to the electrodes of the substrate support. The high-frequency power supply supplies high-frequency power during the ignition period of igniting the plasma within the processing chamber. During the ignition period, the bias power supply sequentially applies a plurality of bias pulses, each a negative voltage, to the electrodes of the substrate support, and progressively or gradually increases the absolute value of the voltage level of the plurality of bias pulses.

[0011] When the absolute value of the bias pulse voltage level increases rapidly, the power of the reflected wave from the high-frequency power increases. In the above embodiment, during plasma ignition, the levels of the plurality of bias pulses increase gradually or in stages. Therefore, according to the above embodiment, the power of the reflected wave from the high-frequency power can be suppressed. Furthermore, since the power of the reflected wave can be suppressed, plasma can be stably generated in a short time, thereby shortening the time until the plasma begins to process the substrate.

[0012] In one illustrated embodiment, the bias power supply may also set the absolute value of the voltage level of each of the plurality of bias pulses to a value greater than the absolute value of the voltage level of any bias pulse previously applied to the electrodes of the substrate support. That is, the absolute value of the voltage level of the plurality of bias pulses sequentially applied to the electrodes of the substrate support during plasma ignition may also ramp up.

[0013] In one illustrated embodiment, the plurality of bias pulses may also each be a DC voltage pulse.

[0014] In one illustrated embodiment, a high-frequency power supply is provided both during the ignition period and during the processing period in which the substrate is processed with plasma in the processing chamber. A bias power supply is also used to sequentially apply a plurality of bias pulses, each with a negative voltage, to the electrodes during the processing period.

[0015] In one illustrated embodiment, the plasma treatment apparatus may further include a pressure controller that adjusts the pressure within the treatment chamber. The pressure controller may also set the pressure within the treatment chamber during treatment to a pressure different from the pressure within the treatment chamber during ignition. Alternatively, the pressure controller may set the pressure within the treatment chamber during treatment to a pressure lower than the pressure within the treatment chamber during ignition.

[0016] In one illustrated embodiment, the high-frequency power supply may also set the frequency of the high-frequency power during the processing period to a frequency different from the frequency of the high-frequency power during the ignition period. Alternatively, the high-frequency power supply may set the frequency of the high-frequency power during the processing period to a frequency lower than the frequency of the high-frequency power during the ignition period.

[0017] In one illustrated embodiment, the high-frequency power supply may also set the power level of the high-frequency power during the processing period to a power level different from the power level of the high-frequency power during the ignition period. The high-frequency power supply may also set the power level of the high-frequency power during the processing period to a higher power level than the power level of the high-frequency power during the ignition period.

[0018] In one exemplary embodiment, the plasma treatment apparatus may further include a gas supply unit that supplies gas to the treatment chamber. The plasma treatment apparatus generates plasma in the treatment chamber using the gas supplied by the gas supply unit. The gas supply unit may also be configured to set the flow rate of at least one gas supplied to the treatment chamber during treatment to a flow rate different from the flow rate of the at least one gas supplied to the treatment chamber during ignition.

[0019] In one illustrated embodiment, the ignition period and the processing period may each include a plurality of periodic pulse periods. The bias power supply may also apply a plurality of bias pulses to the electrodes during the ON period of each of the plurality of pulse periods. In this case, the bias power supply applies a plurality of bias pulses to the electrodes during the ON period of each of the plurality of pulse periods with a bias period shorter than the time interval (i.e., the pulse period) of the ON period. The bias power supply may also stop applying the plurality of bias pulses to the electrodes during the OFF period of each of the plurality of pulse periods.

[0020] In one illustrated embodiment, the bias power supply can also adjust the ratio (i.e., duty cycle) of the duration of each ON period to the duration of the pulse cycle. The bias power supply can also set the duty cycle during the processing period to a ratio different from the duty cycle during the ignition period. The bias power supply can also set the duty cycle during the processing period to a ratio smaller than the duty cycle during the ignition period.

[0021] In one illustrated embodiment, the substrate support can also support the edge ring mounted thereon. The plasma processing apparatus can also apply a plurality of bias pulses, each a negative voltage, to the edge ring.

[0022] In another exemplary embodiment, a plasma processing method is provided. The plasma processing method includes the step of igniting plasma in a processing chamber of a plasma processing apparatus during ignition. The plasma processing apparatus includes a substrate support comprising electrodes and disposed within the processing chamber. The plasma processing method further includes the step of sequentially applying a plurality of bias pulses to the electrodes during ignition. The plurality of bias pulses are negative voltages; the absolute values ​​of the voltage levels of the plurality of bias pulses increase progressively or gradually during ignition.

[0023] Hereinafter, various illustrative embodiments will be described in detail with reference to the drawings. In addition, the same or equivalent parts will be marked with the same symbols in each drawing.

[0024] Figure 1 is a schematic diagram illustrating an example of a plasma treatment apparatus. The plasma treatment apparatus 1 shown in Figure 1 includes a treatment chamber 10. Figure 2 is a schematic diagram showing the structure inside the treatment chamber of an example of a plasma treatment apparatus. As shown in Figure 2, the plasma treatment apparatus 1 can be a capacitively coupled plasma treatment apparatus.

[0025] A processing chamber 10 provides an internal space 10s therein. The central axis of the internal space 10s is an axis AX extending in the vertical direction. In one embodiment, the processing chamber 10 includes a processing chamber body 12. The processing chamber body 12 is generally cylindrical. The internal space 10s is provided within the processing chamber body 12. The processing chamber body 12 is formed, for example, of aluminum. The processing chamber body 12 is electrically grounded. The inner wall surface of the processing chamber body 12, that is, the wall surface that defines the internal space 10s, may also be covered with a plasma-resistant film layer. This film layer may be a ceramic film layer such as a film layer formed by anodizing or a film layer formed by yttrium oxide.

[0026] A passage 12p is provided on the side wall of the processing chamber body 12. The substrate W passes through the passage 12p when it is transported between the internal space 10s and the outside of the processing chamber 10. A gate valve 12g is provided along the side wall of the processing chamber body 12 for opening and closing the passage 12p.

[0027] The plasma processing apparatus 1 further includes a substrate support 16. The substrate support 16 supports the substrate W placed thereon in the processing chamber 10. The substrate W is generally disc-shaped. The substrate support 16 is supported by a support portion 17. The support portion 17 extends upward from the bottom of the processing chamber body 12. The support portion 17 is generally cylindrical. The support portion 17 is formed of an insulating material such as quartz.

[0028] In one embodiment, the substrate support 16 has a lower electrode 18 and an electrostatic chuck 20. The lower electrode 18 and the electrostatic chuck 20 are disposed in the processing chamber 10. The lower electrode 18 is formed of a conductive material such as aluminum and is generally disk-shaped.

[0029] The lower electrode 18 has a flow channel 18f inside it. The flow channel 18f is a flow channel for the heat exchange medium. The heat exchange medium is, for example, a liquid refrigerant. The flow channel 18f receives the heat exchange medium supplied from a heat exchange medium supply device (e.g., a cooling unit) via piping 23a. This supply device is located outside the processing chamber 10. The heat exchange medium supplied to the flow channel 18f flows through the flow channel 18f and returns to the supply device via piping 23b.

[0030] An electrostatic chuck 20 is disposed on the lower electrode 18. As shown in FIG1, the electrostatic chuck 20 has a dielectric portion 20d and an electrode 21a. The electrostatic chuck 20 may also have electrodes 22a and 22b. When the substrate W is processed in the internal space 10s, it is placed on the electrostatic chuck 20 and held by the electrostatic chuck 20. In addition, the substrate support 16 supports the edge ring ER mounted thereon. The edge ring ER is a plate with a generally circular shape. The edge ring ER may be conductive. The edge ring ER is, for example, formed of silicon or silicon carbide. As shown in FIG2, the edge ring ER is mounted on the substrate support 16 with its central axis aligned with the axis AX. The substrate W housed in the processing chamber 10 is disposed on the electrostatic chuck 20 and within the area surrounded by the edge ring ER.

[0031] The plasma processing apparatus 1 may further include a gas line 25. The gas line 25 supplies a heat-conducting gas, such as He gas, from the gas supply mechanism to the gap between the top surface of the electrostatic chuck 20 (the first region described later) and the back surface (bottom surface) of the substrate W.

[0032] The plasma treatment apparatus 1 may further include an outer peripheral portion 28 and an outer peripheral portion 29. The outer peripheral portion 28 extends upward from the bottom of the treatment chamber body 12. The outer peripheral portion 28 is generally cylindrical in shape and extends along the outer periphery of the support portion 17. The outer peripheral portion 28 is formed of a conductive material and is generally cylindrical in shape. The outer peripheral portion 28 is electrically grounded. The surface of the outer peripheral portion 28 may also be covered with a plasma-resistant film layer. This film layer may be a ceramic film layer formed by anodizing or formed by yttrium oxide.

[0033] An outer peripheral portion 29 is provided on the outer peripheral portion 28. The outer peripheral portion 29 is formed of an insulating material. The outer peripheral portion 29 is, for example, formed of ceramic such as quartz. The outer peripheral portion 29 has a generally cylindrical shape. The outer peripheral portion 29 extends along the outer periphery of the lower electrode 18 and the electrostatic chuck 20.

[0034] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is disposed above the substrate support 16. The upper electrode 30, together with the member 32, closes the upper opening of the processing chamber body 12. The member 32 is insulating. The upper electrode 30 is supported on the upper part of the processing chamber body 12 through the member 32.

[0035] The upper electrode 30 may also include a top plate 34 and a support 36. The bottom surface of the top plate 34 delineates an internal space 10s. The top plate 34 provides a plurality of gas holes 34a. Each of the plurality of gas holes 34a penetrates the top plate 34 from the plate thickness direction (vertical direction). The top plate 34 may be formed of silicon, for example. Alternatively, the top plate 34 may have a structure in which a plasma-resistant film layer is formed on the surface of an aluminum component. This film layer may be a ceramic film layer formed by anodizing or formed by yttrium oxide.

[0036] A support body 36 supports the top plate 34 in a detachable manner. The support body 36 is formed, for example, of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. The support body 36 further provides a plurality of gas holes 36b. 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 holes 34a respectively. The support body 36 further provides a gas inlet port 36c. The gas inlet port 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet port 36c.

[0037] A gas source group 40 is connected to the gas supply pipe 38 via a valve group 41, a flow controller group 42, and a valve group 43. The gas source group 40, valve group 41, flow controller group 42, and valve group 43 constitute a gas supply unit. The gas source group 40 includes a plurality of gas sources. Each of the valve groups 41 and 43 includes a plurality of valves (e.g., on / off valves). The flow controller group 42 includes a plurality of flow controllers. Each of the flow controllers in the flow controller group 42 is a mass flow controller or a pressure-controlled flow controller. Each of the plurality of gas sources in the gas source group 40 is connected to the gas supply pipe 38 via a corresponding valve in the valve group 41, a corresponding flow controller in the flow controller group 42, and a corresponding valve in the valve group 43. The plasma processing device 1 can supply gas from one or more gas sources selected from the plurality of gas sources in the gas source group 40 to the internal space for 10 seconds at individually adjusted flow rates.

[0038] A baffle 48 is provided between the outer peripheral portion 28 and the side wall of the processing chamber body 12. The baffle 48 may be made of, for example, an aluminum component coated with a ceramic such as yttrium oxide. A plurality of through holes are formed in the baffle 48. Below the baffle 48, an exhaust pipe 52 is connected to the bottom of the processing 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 turbomolecular pump, which can reduce the pressure in the internal space for 10 seconds.

[0039] Hereinafter, together with FIG1 and FIG2, FIG3 to FIG5 will be referred to. FIG3 and FIG4 are timing diagrams of an example of the processing of the plasma processing apparatus shown in FIG1. ​​FIG5 is a timing diagram of an example of the bias pulse to the substrate and the bias pulse to the edge ring.

[0040] As shown in FIG. 1, the plasma processing apparatus 1 further includes a high-frequency power supply 57. The high-frequency power supply 57 is connected to the lower electrode 18 through a matching adapter 58. The high-frequency power supply 57 is a power source for generating high-frequency power RF for plasma generation. The high-frequency power RF has a frequency in the range of 27 to 100 MHz, for example, a frequency of 40 MHz or 60 MHz. The matching adapter 58 has a matching circuit for matching the impedance of the load side (lower electrode 18 side) of the high-frequency power supply 57 with the output impedance of the high-frequency power supply 57. Alternatively, the high-frequency power supply 57 may not be electrically connected to the lower electrode 18, or it may be connected to the upper electrode 30 through the matching adapter 58.

[0041] In the plasma processing apparatus 1, a high-frequency electric field is generated in the processing chamber 10 using high-frequency power RF from the high-frequency power supply 57. The gas in the processing chamber 10 is excited by the generated high-frequency electric field. As a result, plasma is ignited in the processing chamber 10 and generated. As shown in FIG3, the high-frequency power supply 57 supplies high-frequency power RF to both the ignition period Pi and the processing period Pp. The ignition period Pi is the period during which the plasma is ignited in the processing chamber 10. The processing period Pp is the period after the ignition period Pi. During the processing period Pp, the substrate W is treated by chemical species such as ions and / or free radicals from the plasma generated in the processing chamber 10.

[0042] As shown in FIG. 1, in one embodiment, the substrate support 16 may also have a first region 21 and a second region 22. The first region 21 is the central region of the substrate support 16. The first region 21 includes the central region of the electrostatic chuck 20 and the central region of the lower electrode 18. The second region 22 extends radially outward from the first region 21 along the circumferential direction. The second region 22 includes the peripheral region of the electrostatic chuck 20 and the peripheral region of the lower electrode 18. In the plasma processing apparatus 1, the first region 21 and the second region 22 are formed by a single electrostatic chuck and are integrally formed with each other. In FIG. 1, the boundary between the first region 21 and the second region 22 is shown by a dashed line. In another embodiment, the first region 21 and the second region 22 may also be formed by separate electrostatic chucks.

[0043] The first region 21 supports the substrate W mounted thereon (i.e., on its top surface). The first region 21 is a region with a disk shape. The central axis of the first region 21 is approximately aligned with axis AX. The first region 21 and the second region 22 share a dielectric portion 20d. The dielectric portion 20d is formed of a dielectric such as aluminum nitride or aluminum oxide. The dielectric portion 20d is approximately disk-shaped. In one embodiment, the thickness of the dielectric portion 20d in the second region 22 is smaller than the thickness of the dielectric portion 20d in the first region 21. The position of the top surface of the dielectric portion 20d in the second region 22 in the vertical direction may also be lower than the position of the top surface of the dielectric portion 20d in the first region 21 in the vertical direction.

[0044] The first region 21 has an electrode 21a (clamp electrode). The electrode 21a is a film-shaped electrode disposed within the dielectric portion 20d in the first region 21. A DC power supply 55 is connected to the electrode 21a via a switch 56. When a DC voltage from the DC power supply 55 is applied to the electrode 21a, an electrostatic attraction is generated between the first region 21 and the substrate W. By means of the generated electrostatic attraction, the substrate W is attracted to the first region 21 and held by the first region 21.

[0045] The first region 21 further includes a first electrode 21c. The first electrode 21c is a film-shaped electrode disposed within the dielectric portion 20d in the first region 21. In addition, the electrode 21a may extend in the vertical direction closer to the top surface of the first region 21 than the first electrode 21c.

[0046] The plasma processing apparatus 1 further includes a first bias power supply 61. The first bias power supply 61 is electrically connected to the first electrode 21c. The first bias power supply 61 can also be connected to the first electrode 21c through a filter 62. The filter 62 is an electronic filter that blocks or attenuates the high-frequency power RF from the high-frequency power supply 57.

[0047] As shown in Figures 1 and 5, the first bias power supply 61 sequentially applies a plurality of bias pulses BW to the first electrode 21c. Each of the plurality of bias pulses BW is a voltage pulse. In one embodiment, each of the plurality of bias pulses BW is a negative voltage pulse. In one example, the negative voltage pulse is a negative DC voltage pulse. The output voltage of the first bias power supply 61 may be 0V when no bias pulses BW are output. Alternatively, the output voltage of the first bias power supply 61 may have a voltage level with an absolute value smaller than the absolute value |VBW| of the voltage level VBW of the bias pulses BW when no bias pulses BW are output.

[0048] The first bias power supply 61 can also periodically apply bias pulses BW to the first electrode 21c within a time interval TB defined by the bias frequency fB. The time interval TB is the bias period, which is the reciprocal of the bias frequency fB. The bias frequency fB is, for example, a frequency in the range of 200kHz to 13.56MHz. The proportion of the period during which bias pulses BW are applied to the first electrode 21c within the time interval TB (time length TA) [i.e., the duty cycle DB = TA / TB × 100 (%)] is greater than 0 and less than 100.

[0049] In one embodiment, the ignition period Pi and the processing period Pp described above may each include a plurality of periodic pulse periods PL. As shown in FIG4, each plurality of pulse periods PL includes an ON period PON and an OFF period POFF. That is, the ON period PON occurs at a time interval TP that is the same as the duration of the plurality of pulse periods PL. The first bias power supply 61 may also apply a plurality of bias pulses BW to the first electrode 21c during the ON period PON of each of the periodic plurality of pulse periods PL. The first bias power supply 61 may also stop applying bias pulses BW to the first electrode 21c during the OFF period POFF of each of the plurality of pulse periods PL. The proportion of the ON period PON (duration TON) within the time interval TP [i.e., the duty cycle DP = TON / TP × 100 (%)] is greater than 0 and less than 100. The aforementioned bias period, i.e., the time interval TB, is shorter than the pulse period, i.e., the time interval TP of the PON during the ON period. Therefore, as shown in Figure 5, during each ON period of PON, a number of bias pulses BW are sequentially applied to the first electrode 21c at time intervals TB.

[0050] As shown in FIG1, the second region 22 extends in a manner that surrounds the first region 21. The second region 22 is a generally annular region. The central axis of the second region 22 is roughly aligned with the axis AX. The second region 22 supports the edge ring ER mounted thereon (i.e., above its top surface). The second region 22 shares a dielectric portion 20d with the first region 21.

[0051] In one embodiment, the second region 22 can also retain the edge ring ER using electrostatic attraction. In this embodiment, the second region 22 may have more than one electrode (clamp electrode). In the embodiment shown in FIG1, the second region 22 has a pair of electrodes, namely electrode 22a and electrode 22b. Electrode 22a and electrode 22b are disposed within the dielectric portion 20d in the second region 22. Electrode 22a and electrode 22b constitute a bipolar electrode. Electrode 22a and electrode 22b are each a film-like electrode. Electrode 22a and electrode 22b may also extend at approximately the same height in the vertical direction.

[0052] A DC power supply 71 is connected to electrode 22a via switch 72 and filter 73. Filter 73 is an electronic filter that blocks or attenuates high-frequency power RF, bias pulse BW, and bias pulse BE (described later). A DC power supply 74 is connected to electrode 22b via switch 75 and filter 76. Filter 76 is an electronic filter that blocks or attenuates high-frequency power RF, bias pulse BW, and bias pulse BE.

[0053] DC power supplies 71 and 74 each apply a DC voltage to electrodes 22a and 22b to generate an electrostatic attraction that attracts the edge ring ER to the second region 22. Furthermore, the set potential of electrodes 22a and 22b can be any of positive, negative, or 0V. For example, the potential of electrode 22a can be set to positive and the potential of electrode 22b to negative. Additionally, the potential difference between electrodes 22a and 22b can be formed using a single DC power supply instead of two separate DC power supplies.

[0054] When a DC voltage is applied to electrodes 22a and 22b, an electrostatic attraction is generated between the second region 22 and the edge ring ER. The edge ring ER is attracted to the second region 22 by the generated electrostatic attraction and is held by the second region 22.

[0055] The second region 22 may also have a gas pipeline 22g. The gas pipeline 22g is provided for supplying heat-conducting gas GHT (e.g., He gas) to the gap between the second region 22 and the edge ring ER. The gas pipeline 22g is connected to the source of the heat-conducting gas GHT (i.e., the gas supply mechanism 86).

[0056] The second region 22 may also have a second electrode 22c. The second electrode 22c is a film-shaped electrode. The second electrode 22c is disposed within the dielectric portion 20d in the second region 22. The second electrode 22c is separate from the first electrode 21c. In addition, electrodes 22a and 22b may extend in the vertical direction closer to the top surface of the second region 22 than the second electrode 22c. In addition, the second electrode 22c may also be disposed on the outer side of the second region 22. For example, the second electrode 22c may also be disposed below the edge ring ER and disposed in the outer peripheral portion 29.

[0057] The plasma processing apparatus 1 may further include a second bias power supply 81. The second bias power supply 81 is electrically connected to the second electrode 22c. The second bias power supply 81 may also be connected to the second electrode 22c through a filter 82. The filter 82 is an electronic filter that blocks or attenuates high-frequency power RF.

[0058] As shown in Figures 1 and 5, the second bias power supply 81 sequentially applies a plurality of bias pulses BE to the second electrode 22c. The plurality of bias pulses BE are applied to the edge ring ER through the second electrode 22c. Each of the plurality of bias pulses BE is a voltage pulse. In one embodiment, each of the plurality of bias pulses BE is a negative voltage pulse. In one example, the negative voltage pulse is a negative DC voltage pulse. The output voltage of the second bias power supply 81 may be 0V when no bias pulse BE is output. Alternatively, the output voltage of the second bias power supply 81 may have a voltage level with an absolute value smaller than the absolute value |VBE| of the voltage level VBE of the bias pulse BE when no bias pulse BE is output. The bias pulse BE may be synchronized with the bias pulse BW. Alternatively, the bias pulse BE may not be synchronized with the bias pulse BW.

[0059] The second bias power supply 81 can also periodically apply bias pulses BE to the second electrode 22c at time intervals TBE. The time interval TBE is the bias period, which is the reciprocal of the bias frequency fBE. The bias frequency fBE is, for example, a frequency in the range of 200kHz to 13.56MHz. The time interval TBE can be the same as or different from the time interval TB, as shown in Figure 5.

[0060] The proportion of the period during which a bias pulse BE is applied to the second electrode 22c within the time interval TBE (time length TAE) [i.e., duty ratio DBE = TAE / TBE × 100 (%)] is greater than 0 and less than 100. The time length TAE can be the same as or different from the time length TA, as shown in Figure 5. Furthermore, the duty ratio DBE can be the same as or different from the duty ratio DB.

[0061] In one embodiment, the ignition period Pi and the processing period Pp described above may each include a plurality of periodic pulse periods PL_E. As shown in FIG4, each of the plurality of pulse periods PL_E includes an ON period PON_E and an OFF period POFF_E. That is, the ON period PON_E occurs at a time interval TP_E that is the same length as the plurality of pulse periods PL_E. The second bias power supply 81 may also apply a plurality of bias pulses BE to the second electrode 22c during the ON period PON_E of each of the periodic plurality of pulse periods PL_E. The second bias power supply 81 may also stop applying bias pulses BE to the second electrode 22c during the OFF period POFF_E of each of the plurality of pulse periods PL_E. The proportion of PON_E (duration TON_E) during the ON period within the time interval TP_E [i.e., the duty cycle DP_E = TON_E / TP_E × 100 (%)] is greater than 0 and less than 100. The aforementioned bias period, i.e., the time interval TBE, is shorter than the pulse period, i.e., the time interval TP_E of PON_E during the ON period. Therefore, as shown in Figure 5, in each ON period PON_E, a number of bias pulses BE are sequentially applied to the second electrode 22c at time interval TBE. In addition, the ON period PON_E can be synchronized with the ON period PON. Alternatively, the ON period PON_E may not be synchronized with the ON period PON.

[0062] In one embodiment, the high-frequency power supply 57 can also supply high-frequency power RF during the ON period PON_R of each of the periodic multiple pulse periods PL_R during the ignition period Pi and the processing period Pp, as shown in FIG4. That is, the high-frequency power supply 57 can also supply high-frequency power RF during the ON period PON_R that occurs at a time interval TP_R. The high-frequency power supply 57 can also stop supplying high-frequency power RF during the OFF period POFF_R of each of the multiple pulse periods PL_R. The proportion of the ON period PON_R (time TON_R) within the time interval TP_R [i.e., the duty cycle DP_R = TON_R / TP_R × 100 (%)] is greater than 0 and less than 100. In addition, the ON period PON_R can be synchronized with the ON period PON and the ON period PON_E. During the ON period, PON_R may not be synchronized with at least one of the ON period PON and the ON period PON_E.

[0063] In one embodiment, the plasma processing apparatus 1 may further include a power supply 88. The power supply 88 applies a voltage DCS to the upper electrode 30. The power supply 88 may apply the voltage DCS to the upper electrode 30 during both the ignition period Pi and the processing period Pp. The voltage DCS may be a negative voltage. The voltage DCS may also be a negative DC voltage.

[0064] In one embodiment, the power supply 88 may also apply a voltage DCS to the upper electrode 30 during the ON period PON_D of each of the periodic multiple pulse periods of PL_D during the ignition period Pi and the processing period Pp, as shown in FIG4. That is, the power supply 88 may also apply a voltage DCS to the upper electrode 30 during the ON period PON_D that occurs at a time interval TP_D. The power supply 88 may also stop applying the power supply 88 during the OFF period POFF_D of each of the multiple pulse periods of PL_D. The proportion of the ON period PON_D (time TON_D) within the time interval TP_D [i.e., the duty cycle DP_D = TON_D / TP_D × 100 (%)] is greater than 0 and less than 100. In addition, PON_D during the ON period can be synchronized with PON during the ON period, PON_R during the ON period, and PON_E during the ON period. PON_D during the ON period may also not be synchronized with at least one of PON during the ON period, PON_R during the ON period, and PON_E during the ON period.

[0065] In one embodiment, the plasma processing apparatus 1 may also include a control unit MC, as shown in FIG2. The control unit MC is a computer equipped with a processor, a memory device, an input device, a display device, etc., which controls various parts of the plasma processing apparatus 1. Specifically, the control unit MC executes the control program stored in the memory device and controls various parts of the plasma processing apparatus 1 according to the formula data stored in the memory device. Through the control of the control unit MC, the program specified in the formula data is implemented in the plasma processing apparatus 1.

[0066] Hereinafter, together with Figures 1 to 5, and referring to Figure 6, a plasma treatment method of an exemplary embodiment will be described. Furthermore, detailed examples of the operation of each part of the plasma treatment apparatus 1 will be described. Figure 6 is a flowchart of a plasma treatment method of an exemplary embodiment.

[0067] In the plasma processing method shown in FIG. 6 (hereinafter referred to as "Method MT"), the edge ring ER is held by the second region 22, and the substrate W is held by the first region 21 of the substrate support 16. Then, the gas supply unit supplies processing gas into the processing chamber 10. In the example shown in FIG. 3, the gas supply unit supplies processing gas into the processing chamber 10 starting from time point t0. The supply of processing gas into the processing chamber continues during the ignition period Pi and the processing period Pp. In addition, the exhaust device 50 (its pressure controller) adjusts the pressure in the processing chamber 10 to a specified pressure. In addition, the gas supply mechanism 86 starts supplying heat-conducting gas GHT at a time point between time point t0 and the start time point t1 of the ignition period Pi. The heat-conducting gas GHT is supplied to the gap between the second region 22 and the edge ring ER. The supply of heat-conducting gas GHT continues during the ignition period Pi and the processing period Pp.

[0068] Then, step STa is performed during ignition period Pi. That is, during ignition period Pi, the plasma is ignited in the processing chamber 10. During ignition period Pi, the high-frequency power supply 57 supplies high-frequency power RF. In the example shown in Figure 3, the high-frequency power RF is supplied at time point t1.

[0069] Furthermore, step STb is performed during ignition period Pi. In step STb, the first bias power supply 61 sequentially applies a plurality of bias pulses BW to the first electrode 21c. In the example shown in FIG3, the application of the plurality of bias pulses BW to the first electrode 21c begins at time t3 after time t1 and continues during ignition period Pi. In addition, in step STb, the first bias power supply 61 increases the absolute value |VBW| of the voltage level VBW of the plurality of bias pulses BW in stages or gradually.

[0070] In one embodiment, during ignition period Pi, the first bias power supply 61 sets the absolute value of the voltage level of each of the plurality of bias pulses BW to a value larger than the absolute value of the voltage level of any bias pulse BW previously applied to the first electrode 21c. In other words, as shown in FIG5, the absolute value of the voltage level |VBW| of the plurality of bias pulses BW sequentially applied to the first electrode 21c during ignition period Pi can be ramped up.

[0071] When the absolute value of the bias pulse BW voltage level increases sharply, the power of the reflected wave from the high-frequency power RF increases. In the plasma processing apparatus 1, during the ignition period Pi, the levels of the plurality of bias pulses BW increase gradually or intermittently. Therefore, according to the plasma processing apparatus 1, the power of the reflected wave from the high-frequency power RF can be suppressed. Furthermore, since the power of the reflected wave is suppressed, plasma can be stably generated in a short time, thereby shortening the time until the plasma treatment of the substrate begins.

[0072] In one embodiment, the second bias power supply 81 sequentially applies a plurality of bias pulses BE to the second electrode 22c during the ignition period Pi. The plurality of bias pulses BE are applied to the edge ring ER through the second electrode 22c. In the example shown in FIG3, the application of the plurality of bias pulses BE to the second electrode 22c begins at time t3 and continues during the ignition period Pi. In addition, the second bias power supply 81 increases the absolute value of the voltage level VBE of the plurality of bias pulses BE, |VBE|, in stages or gradually. At this time, the power of the reflected wave of the high-frequency power RF can also be suppressed.

[0073] In one embodiment, during the ignition period Pi, the second bias power supply 81 sets the absolute value of the voltage level of each of the plurality of bias pulses BE to a value larger than the absolute value of the voltage level of any bias pulse BE previously applied to the second electrode 22c. In other words, as shown in FIG5, the absolute value of the voltage level |VBE| of the plurality of bias pulses BE sequentially applied to the second electrode 22c during the ignition period Pi can be ramped up.

[0074] In one embodiment, the power supply 88 applies a voltage DCS to the upper electrode 30 during ignition period Pi. In the example shown in FIG3, the application of the voltage DCS to the upper electrode 30 begins at time t2 between time t1 and time t3 and continues during ignition period Pi.

[0075] In method MT, step STc is then performed. Step STc is performed during processing period Pp after ignition period Pi. In the example shown in FIG3, processing period Pp begins at time t4. During processing period Pp, the substrate W is processed in processing chamber 10 using plasma that has been continuously generated since ignition period Pi.

[0076] In one embodiment, the gas supply unit may also set the flow rate of at least one gas supplied to the processing chamber 10 during the processing period Pp to a flow rate different from the flow rate of the at least one gas supplied to the processing chamber 10 during the ignition period Pi. The flow rate of the at least one gas may also be changed at time point t5 after time point t4. The time between time point t4 and time point t5 is long, for example, 0.6 seconds.

[0077] The processing gas includes, for example, a deposition gas and an oxygen-containing gas. The deposition gas is, for example, a carbon-containing gas such as fluorocarbon gas. The oxygen-containing gas is, for example, O2 gas. The gas supply unit may also set the flow rate of the deposition gas supplied to the processing chamber 10 during processing Pp to be smaller than the flow rate of the deposition gas supplied to the processing chamber 10 during ignition Pi. The gas supply unit may also set the flow rate of the oxygen-containing gas supplied to the processing chamber 10 during processing Pp to be larger than the flow rate of the oxygen-containing gas supplied to the processing chamber 10 during ignition Pi.

[0078] In one embodiment, the pressure controller of the exhaust device 50 can also set the pressure in the processing chamber 10 during the processing period Pp to a pressure different from the pressure in the processing chamber 10 during the ignition period Pi. The pressure controller can also set the pressure in the processing chamber 10 during the processing period Pp, as shown by the solid line in Figure 3, to a lower pressure than the pressure in the processing chamber 10 during the ignition period Pi. When the pressure in the processing chamber 10 during the processing period Pp is above a threshold, the pressure controller can also set the pressure in the processing chamber 10 during the ignition period Pi (the pressure shown by the dashed line in Figure 3) to the same pressure as the pressure in the processing chamber 10 during the processing period Pp. When the pressure in the processing chamber 10 during the processing period Pp is lower than the threshold, the pressure controller can also set the pressure in the processing chamber 10 during the ignition period Pi to the same value as the threshold. The threshold for the pressure in the processing chamber 10 is, for example, 2.666 Pa (20 mTorr).

[0079] High-frequency power supply 57, in order to continuously generate plasma from the processing gas from Pi during the ignition period, also supplies high-frequency power RF during Pp during the processing period.

[0080] In one embodiment, the high-frequency power supply 57 can also set the frequency of the high-frequency power RF in Pp during the processing period to a frequency different from the frequency of the high-frequency power RF in Pi during the ignition period. As shown in FIG3, the high-frequency power supply 57 can also set the frequency of the high-frequency power RF in Pp during the processing period to a frequency lower than the frequency of the high-frequency power RF in Pi during the ignition period.

[0081] In one embodiment, the high-frequency power supply 57 may also set the power level of the high-frequency power RF during the processing period Pp to a power level different from the power level of the high-frequency power RF during the ignition period Pi. The high-frequency power supply 57 may also set the power level of the high-frequency power RF during the processing period Pp, as shown by the solid line in Figure 3, to a higher power level than the power level of the high-frequency power RF during the ignition period Pi. When the power level of the high-frequency power RF during the processing period Pp is below a threshold, the high-frequency power supply 57 may also set the power level of the high-frequency power RF during the ignition period Pi to the same level as the power level of the high-frequency power RF during the processing period Pp. Please refer to the power level of the high-frequency power RF shown by the dashed line in Figure 3. When the power level of the high-frequency power RF during the processing period Pp is greater than the threshold, the high-frequency power supply 57 may also set the power level of the high-frequency power RF during the ignition period Pi to the same value as the threshold. The threshold for the power level of a high-frequency power RF, for example, is 2500W.

[0082] In one embodiment, the high-frequency power supply 57 may also set the duty ratio DP_R during the processing period Pp to a ratio different from the duty ratio DP_R during the ignition period Pi. The high-frequency power supply 57 may also set the duty ratio DP_R during the processing period Pp to a ratio smaller than the duty ratio DP_R during the ignition period Pi. When the duty ratio DP_R during the processing period Pp is above a threshold, the high-frequency power supply 57 may also set the duty ratio DP_R during the ignition period Pi to the same ratio as the duty ratio DP_R during the processing period Pp. When the duty ratio DP_R during the processing period Pp is smaller than the threshold, the high-frequency power supply 57 may also set the duty ratio DP_R during the ignition period Pi to the same value as the threshold. The threshold for the duty ratio DP_R is, for example, 30%.

[0083] During the processing period Pp, the first bias power supply 61 also sequentially applies a plurality of bias pulses BW to the first electrode 21c. Alternatively, during the processing period Pp, similar to the ignition period Pi, a plurality of bias pulses BW can be sequentially applied to the first electrode 21c periodically. The voltage levels of the plurality of bias pulses BW can be the same during the processing period Pp.

[0084] In one embodiment, the first bias power supply 61 may also set the duty ratio DP during the processing period Pp to a ratio different from the duty ratio DP during the ignition period Pi. The first bias power supply 61 may also set the duty ratio DP during the processing period Pp, as shown by the solid line in Figure 3, to a ratio smaller than the duty ratio DP during the ignition period Pi. When the duty ratio DP during the processing period Pp is above a threshold, as shown by the dashed line in Figure 3, the first bias power supply 61 may also set the duty ratio DP during the ignition period Pi to the same ratio as the duty ratio DP during the processing period Pp. When the duty ratio DP during the processing period Pp is smaller than the threshold, the first bias power supply 61 may also set the duty ratio DP during the ignition period Pi to the same value as the threshold. The threshold for the duty ratio DP is, for example, 30%.

[0085] During the processing period Pp, the second bias power supply 81 also sequentially applies a plurality of bias pulses BE to the second electrode 22c. Alternatively, during the processing period Pp, similar to the ignition period Pi, a plurality of bias pulses BE can be sequentially applied to the second electrode 22c periodically. The voltage levels of the plurality of bias pulses BE can be the same during the processing period Pp.

[0086] In one embodiment, the second bias power supply 81 may also set the duty ratio DP_E during the processing period Pp to a ratio different from the duty ratio DP_E during the ignition period Pi. The second bias power supply 81 may also set the duty ratio DP_E during the processing period Pp to a ratio smaller than the duty ratio DP_E during the ignition period Pi. When the duty ratio DP_E during the processing period Pp is above a threshold, the second bias power supply 81 may also set the duty ratio DP_E during the ignition period Pi to a ratio the same as the duty ratio DP_E during the processing period Pp. When the duty ratio DP_E during the processing period Pp is smaller than the threshold, the second bias power supply 81 may also set the duty ratio DP_E during the ignition period Pi to a value the same as the threshold. The threshold for the duty ratio DP_E is, for example, 30%.

[0087] During the processing period Pp, the power supply 88 also applies a voltage DCS to the upper electrode 30. The voltage level of the DCS during the processing period Pp can be the same as the voltage level of the DCS during the ignition period Pi.

[0088] In one embodiment, the power supply 88 may also set the duty ratio DP_D during the processing period Pp to a ratio different from the duty ratio DP_D during the ignition period Pi. The power supply 88 may also set the duty ratio DP_D during the processing period Pp to a ratio smaller than the duty ratio DP_D during the ignition period Pi. When the duty ratio DP_D during the processing period Pp is above a threshold, the power supply 88 may also set the duty ratio DP_D during the ignition period Pi to the same ratio as the duty ratio DP_D during the processing period Pp. When the duty ratio DP_D during the processing period Pp is smaller than the threshold, the power supply 88 may also set the duty ratio DP_D during the ignition period Pi to the same value as the threshold. The threshold for the duty ratio DP_D is, for example, 30%.

[0089] The gas supply mechanism 86 also supplies heat-conducting gas GHT to the gap between the second region 22 and the edge ring ER during the processing period Pp. The gas supply mechanism 86 may also set the pressure of the heat-conducting gas GHT in Pp during the processing period to a pressure different from the pressure of the heat-conducting gas GHT in Pi during the ignition period. Alternatively, the gas supply mechanism 86 may set the pressure of the heat-conducting gas GHT in Pp during the processing period to a pressure higher than the pressure of the heat-conducting gas GHT in Pi during the ignition period.

[0090] The above description is for various illustrative embodiments, but it is not limited to the embodiments exemplified above. Various additions, omissions, substitutions, and changes can also be implemented. In addition, elements from different embodiments can be combined to form other embodiments.

[0091] For example, in another embodiment, the bias pulse BW from the first bias power supply 61 can also be applied to the lower electrode 18. In this case, the plasma processing apparatus 1 may not have the first electrode 21c. The bias pulse BW from the first bias power supply 61 can also be applied to the electrode 21a. Similarly, in this case, the plasma processing apparatus 1 may not have the first electrode 21c.

[0092] In another embodiment, the bias pulse BE from the second bias power supply 81 can also be applied to electrodes 22a and 22b. In this case, the plasma processing apparatus 1 may not have a second electrode 22c.

[0093] In another embodiment, the plasma processing apparatus may be a capacitively coupled plasma processing apparatus different from plasma processing apparatus 1. In another embodiment, the plasma processing apparatus may be other types of plasma processing apparatus. Other types of plasma processing apparatus may be inductively coupled plasma processing apparatus, electron cyclotron resonance (ECR) plasma processing apparatus, or plasma processing apparatus that generates plasma using surface waves such as microwaves.

[0094] In another embodiment, the voltage levels of the plurality of bias pulses BW can also change from positive voltage levels to negative voltage levels in stages or gradually. Similarly, after switching from a positive voltage pulse to a negative voltage pulse, the absolute value |VBW| of the voltage levels VBW of the plurality of bias pulses BW increases in stages or gradually as described above. Likewise, the voltage levels of the plurality of bias pulses BE can also change from positive voltage levels to negative voltage levels in stages or gradually. Similarly, after switching from a positive voltage pulse to a negative voltage pulse, the absolute value |VBE| of the voltage levels VBE of the plurality of bias pulses BE increases in stages or gradually as described above.

[0095] The following describes experiments 1 to 4. In experiments 1 to 4, the power of the reflected wave of the high-frequency electric power RF in Pi during ignition was measured using the plasma processing apparatus 1. In experiments 1 to 3, between time points t3 and t4 within Pi during ignition, the absolute values ​​of the voltage levels of a plurality of bias pulses BW were ramped up from 0V to 9500V. The time intervals between time points t3 and t4 in experiments 1 to 3 were 1 second, 2 seconds, and 3 seconds, respectively. Furthermore, in experiment 4, between time points t3 and t4 within Pi during ignition, the absolute values ​​of the voltage levels of a plurality of bias pulses BW were progressively increased to 2500V, 6000V, and 9500V.

[0096] Figures 7(a) and 7(b) are graphs representing the absolute value of the bias pulse BW voltage level |VBW| and the power Pr of the reflected wave from the high-frequency power RF in Experiment 1, respectively. Figures 8(a) and 8(b) are graphs representing the absolute value of the bias pulse BW voltage level |VBW| and the power Pr of the reflected wave from the high-frequency power RF in Experiment 2, respectively. Figures 9(a) and 9(b) are graphs representing the absolute value of the bias pulse BW voltage level |VBW| and the power Pr of the reflected wave from the high-frequency power RF in Experiment 3, respectively. Figures 10(a) and 10(b) are graphs representing the absolute value of the bias pulse BW voltage level |VBW| and the power Pr of the reflected wave from the high-frequency power RF in Experiment 4, respectively. As shown in the diagrams, by progressively or gradually increasing the absolute value |VBW| of the electrical level of a plurality of bias pulses BW, the power Pr of the reflected wave from the high-frequency electrical RF can be suppressed, a point we have confirmed. In particular, in experiments 3 and 4, by ramping up the absolute value |VBW| from 0V to 9500V over a period of more than 2 seconds, the power Pr of the reflected wave from the high-frequency electrical RF after the bias pulses BW were applied was significantly suppressed.

[0097] Based on the above description, it should be understood that the various embodiments of the present invention are described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of the invention. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and their true scope and spirit are indicated by the appended claims. [Simplified Explanation of the Diagram]

[0008] [Fig. 1] is a schematic diagram showing an example of a plasma processing apparatus. [Fig. 2] is a diagram showing the structure of the processing chamber of an example of a plasma processing apparatus. [Fig. 3] is a timing diagram of an example of the processing of the plasma processing apparatus shown in Fig. 1. [Fig. 4] is a timing diagram of an example of the processing of the plasma processing apparatus shown in Fig. 1. [Fig. 5] is a timing diagram of an example of the bias pulse for the substrate and the bias pulse for the edge ring. [Fig. 6] is a flowchart of an example of a plasma processing method. [Fig. 7] (a) and (b) are graphs showing the absolute value of the voltage level of the bias pulse and the reflected wave of the high-frequency power in the first experiment, respectively. [Fig. 8] (a) and (b) are graphs showing the absolute value of the voltage level of the bias pulse and the reflected wave of the high-frequency power in the second experiment, respectively. [Figure 9] (a) and (b) are graphs showing the absolute value of the bias pulse voltage level and the reflected wave of the high-frequency power in Experiment 3, respectively. [Figure 10] (a) and (b) are graphs showing the absolute value of the bias pulse voltage level and the reflected wave of the high-frequency power in Experiment 4, respectively.

Claims

1. A plasma processing apparatus, comprising: a processing chamber; a substrate support including electrodes and disposed within the processing chamber; a high-frequency power supply for supplying high-frequency power to generate plasma from gas within the processing chamber; a bias power supply electrically connected to the electrodes; and a controller for: controlling the high-frequency power supply to supply the high-frequency power during an ignition period for igniting the plasma within the processing chamber; and controlling the bias power supply to sequentially apply a plurality of pure negative voltage bias pulses to the electrodes during the ignition period, and progressively or gradually increasing the absolute value of the voltage level of the negative voltage bias pulses.

2. The plasma treatment apparatus as claimed in claim 1, wherein, These negative voltage bias pulses are each a DC voltage pulse.

3. The plasma treatment apparatus as claimed in claim 1, wherein, The controller is used to: control the high-frequency power supply to also supply the high-frequency power during the processing of the substrate in the processing chamber after the ignition period; and control the bias power supply to also sequentially apply the negative voltage bias pulses to the electrodes during the processing period.

4. The plasma treatment apparatus as described in claim 3, wherein, It further includes a pressure controller that adjusts the pressure inside the processing chamber; the pressure controller sets the pressure inside the processing chamber during the processing period to a pressure different from the pressure inside the processing chamber during the ignition period.

5. The plasma treatment apparatus as claimed in claim 4, wherein, The pressure controller sets the pressure in the processing chamber during the processing period to a lower pressure than the pressure in the processing chamber during the ignition period.

6. The plasma treatment apparatus as claimed in claim 3, wherein, The controller controls the high-frequency power supply and sets the frequency of the high-frequency power during the processing period to a frequency different from the frequency of the high-frequency power during the ignition period.

7. The plasma treatment apparatus as claimed in claim 6, wherein, The controller controls the high-frequency power supply to set the frequency of the high-frequency power during the processing period to a lower frequency than the frequency of the high-frequency power during the ignition period.

8. The plasma treatment apparatus as claimed in claim 3, wherein, The controller controls the high-frequency power supply to set the power level of the high-frequency power during the processing period to a power level different from the power level of the high-frequency power during the ignition period.

9. The plasma treatment apparatus as claimed in claim 8, wherein, The controller controls the high-frequency power supply to set the power level of the high-frequency power during the processing period to a higher power level than the power level of the high-frequency power during the ignition period.

10. The plasma treatment apparatus as claimed in claim 3, wherein, It further includes a gas supply unit that supplies gas into the processing chamber to which plasma is subsequently generated; and a controller that controls the gas supply unit to set the flow rate of at least one gas supplied to the processing chamber during the processing period to a flow rate different from that of the at least one gas supplied to the processing chamber during the ignition period.

11. The plasma treatment apparatus as claimed in claim 3, wherein, The ignition period and the processing period each include a periodic plurality of pulse periods; the controller controls the bias power supply to apply the negative voltage bias pulses to the electrode during the on period of each of the plurality of pulse periods with a bias period shorter than the pulse period which is the time interval of the on period, and to stop applying the negative voltage bias pulses to the electrode during the off period of each of the plurality of pulse periods.

12. The plasma processing apparatus as claimed in claim 11, wherein, The controller controls the bias power supply, adjusts the ratio of the duration of each conduction period to the duration of the pulse cycle, i.e., the working ratio, and sets the working ratio during the processing period to a ratio different from the working ratio during the ignition period.

13. The plasma processing apparatus as claimed in claim 12, wherein, The controller controls the bias power supply to set the duty cycle during the processing period to a smaller ratio than the duty cycle during the ignition period.

14. The plasma processing apparatus as claimed in claim 1, wherein, The substrate support supports the edge ring mounted thereon; the plasma processing apparatus further includes another bias power supply that applies the negative voltage bias pulses to the edge ring.

15. The plasma treatment apparatus as claimed in claim 1, wherein, The controller controls the bias power supply so that each of the negative voltage bias pulses is a constant voltage.

16. The plasma treatment apparatus as claimed in claim 1, wherein, Following the ignition period, a subsequent processing period is performed in the processing chamber using the plasma ignited during the ignition period to process the substrate.

17. The plasma processing apparatus as claimed in claim 16, wherein, The controller controls the bias power supply to sequentially apply a plurality of pure negative voltage bias pulses to the electrode during the processing.

18. The plasma processing apparatus as claimed in claim 17, wherein, The absolute values ​​of the voltage levels of the negative voltage bias pulses applied during this process are constant relative to each other.

19. A plasma processing method comprising: igniting plasma in a processing chamber of a plasma processing apparatus during ignition; the plasma processing apparatus including a substrate support; the substrate support including an electrode and disposed in the processing chamber; and sequentially applying a plurality of pure negative voltage bias pulses to the electrode during the ignition; wherein the absolute value of the voltage level of the negative voltage bias pulses increases periodically or gradually during the ignition.

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