Plasma processing apparatus and plasma processing method

Abstract

To provide a technique capable of improving plasma ignitability without using a rare gas.SOLUTION: A plasma processing device comprises: a processing container 1 to which plasma processing is applied; a mounting table 3 which is also used as a lower electrode and on which a substrate is mounted; a metal window 2 connected to a ground; an inductive coupling antenna 70 which is disposed while keeping electrical insulation from the metal window 2; and a control unit 9 which controls the plasma processing. The control unit 9 executes: first control of supplying a first high frequency to the mounting table 3 by first power to ignite plasma by capacitive coupling between the metal window 2 and the mounting table 3; second control of supplying a second high frequency to the inductive coupling antenna 70 by second power to maintain the plasma by inductive coupling via the metal window 2; and third control of changing the first high frequency into third power greater than the first power and applying the plasma processing to the substrate mounted on the mounting table.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a plasma processing apparatus and a plasma processing method. [Background technology]

[0002] 2. Description of the Related Art A plasma processing apparatus that processes a substrate by using inductively coupled plasma is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-17646 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique capable of improving plasma ignition performance without using a rare gas. [Means for solving the problem]

[0005] A plasma processing apparatus according to one embodiment of the present disclosure includes a processing vessel in which a plasma processing is performed on a substrate using plasma; a mounting stage disposed inside the processing vessel, which also serves as a lower electrode and on which the substrate is placed; a metal window that forms a ceiling portion of the processing vessel while maintaining electrical insulation from the processing vessel and is connected to ground; an inductively coupled antenna that faces the mounting stage through the metal window and is disposed while maintaining electrical insulation from the metal window; and a control unit that controls the plasma processing, the control unit executing a first control of supplying a first high frequency wave at a first power to the mounting stage and igniting the plasma by capacitive coupling between the metal window and the mounting stage; a second control of supplying a second high frequency wave at a second power to the inductively coupled antenna and maintaining the plasma by inductive coupling via the metal window; and a third control of changing the first high frequency wave to a third power greater than the first power and performing the plasma processing on the substrate placed on the mounting stage. Effect of the Invention

[0006] According to the present disclosure, it is possible to improve plasma ignition performance without using a rare gas. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing a plasma processing apparatus according to an embodiment; [Diagram 2] FIG. 1 shows a plasma processing method according to an embodiment. [Diagram 3] FIG. 13 is a diagram showing a plasma processing method according to a modified example of the embodiment. [Figure 4] FIG. 3 is a diagram showing plasma ignition properties when the plasma processing method shown in FIG. 2 is carried out. [Diagram 5] FIG. 4 is a diagram showing plasma ignition properties when the plasma processing method shown in FIG. 3 is carried out. [Figure 6] Graph showing plasma ignition performance when offset time is changed (1) [Figure 7] Graph (2) showing plasma ignition performance when offset time is changed [Figure 8]Figure (3) showing plasma ignition performance when the offset time is changed [Figure 9] Graph showing plasma ignition characteristics when the processing gas is changed (1) [Figure 10] Graph (2) showing plasma ignition characteristics when the processing gas is changed [Figure 11] Graph (3) showing plasma ignition characteristics when the processing gas is changed [Figure 12] A diagram showing plasma ignition performance when multi-step processing is performed. [Figure 13] FIG. 13 is a diagram showing the amount of scraping of a target film processed by the first control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all of the accompanying drawings, the same or corresponding members or parts are designated by the same or corresponding reference numerals, and duplicated descriptions will be omitted.

[0009] [Plasma Processing Apparatus] The plasma processing apparatus according to the embodiment will be described with reference to Fig. 1. The plasma processing apparatus includes a processing vessel 1, a metal window 2, a mounting table 3, a plasma generating unit 7, and a control unit 9.

[0010] The processing vessel 1 is a vacuum vessel in which the pressure can be reduced. The processing vessel 1 accommodates a mounting table 3 therein. The processing vessel 1 is made of a metal material such as aluminum or stainless steel. The processing vessel 1 is connected to ground.

[0011] A load / unload port 11 is provided on a side surface of the processing vessel 1. The load / unload port 11 is an opening for transferring a substrate G to be plasma processed. A gate valve 12 is provided at the load / unload port 11. The gate valve 12 opens and closes the load / unload port 11. The substrate G is, for example, a rectangular glass substrate.

[0012] An exhaust port 13 is provided on the bottom surface of the processing vessel 1. The exhaust port 13 may be provided at one location as shown in Fig. 1, or may be provided at multiple locations. An exhaust unit 15 is connected to the exhaust port 13 via an exhaust pipe 14. The exhaust unit 15 adjusts the pressure inside the processing vessel 1. The exhaust unit 15 includes a vacuum pump and a pressure adjustment valve (neither of which are shown).

[0013] The metal window 2 seals the upper part of the processing vessel 1 via an insulating member 16, and is supported by being suspended from the ceiling of an antenna chamber (not shown) provided adjacent to the upper part of the processing vessel 1. The metal window 2 forms the ceiling of the processing vessel 1 while maintaining electrical insulation from the processing vessel 1. The metal window 2 functions as a shower head for supplying a processing gas into the processing vessel 1. The metal window 2 is formed by a plurality of divided windows 2a. The plurality of divided windows 2a are electrically insulated from each other via an insulating member 2b. The plurality of divided windows 2a are arranged, for example, radially in a top view. The plurality of divided windows 2a may be arranged in a lattice shape in a top view. The arrangement of the plurality of divided windows 2a is not limited to the above. The number of divided windows 2a is not particularly limited, and may be, for example, 20. The metal window 2 may be formed by a single member.

[0014] Each partition window 2a has a gas dispersion chamber 20 and a gas supply hole 21. The gas dispersion chamber 20 is formed inside each partition window 2a. A plurality of gas supply holes 21 are formed on the lower surface of each partition window 2a so as to face the upper surface of the mounting table 3. The gas supply holes 21 communicate with the gas dispersion chamber 20. A gas supply source 23 is connected to each gas dispersion chamber 20 via a gas supply pipe 22. The gas supply source 23 is a supply source of a processing gas. The type of the processing gas is not limited, and may be, for example, carbon tetrafluoride (CF4), oxygen (O2), or argon (Ar). A flow rate adjustment unit 24 and a valve 25 are interposed in the gas supply pipe 22 in this order from the gas supply source 23 side. A processing gas with a flow rate adjusted is supplied to each gas dispersion chamber 20 via the gas supply pipe 22.

[0015] Each of the partition windows 2a is connected to the ground via an impedance adjustment circuit 26. The impedance adjustment circuit 26 adjusts the impedance between each of the partition windows 2a and the ground. Note that each of the partition windows 2a may be connected to the ground without going through the impedance adjustment circuit 26.

[0016] The mounting table 3 has a prismatic shape with a rectangular planar shape. The substrate G is placed on the mounting table 3. The mounting table 3 is configured by stacking a spacer 35 and a susceptor 33 in this order from below, and covering the side surfaces of the spacer 35 and the susceptor 33 with a cover 38 made of, for example, ceramic. The mounting table 3 is installed in the center of the bottom surface of the processing vessel 1 with an insulating layer 39 interposed therebetween.

[0017] A heat transfer gas supply path 34 is provided inside the mounting table 3. The downstream end of the heat transfer gas supply path 34 branches into multiple parts, which open in a dispersed manner on the upper surface of the mounting table 3 to form multiple heat transfer gas supply ports 34a. The upstream side of the heat transfer gas supply path 34 is connected to a heat transfer gas supply pipe 62 provided outside the processing chamber 1. The upstream side of the heat transfer gas supply pipe 62 is connected to a heat transfer gas supply source 64 via a flow rate adjustment unit 63. The multiple heat transfer gas supply ports 34a supply the heat transfer gas to a minute gap between the lower surface of the substrate G placed on the upper surface of the mounting table 3 and the upper surface of the mounting table 3.

[0018] An annular coolant flow passage 36 extending in the circumferential direction, for example, is provided inside the spacer 35. A coolant adjusted to a predetermined temperature by a chiller unit (not shown) is circulated and supplied to the coolant flow passage 36. By controlling the temperature of the coolant, the temperature of the substrate G can be adjusted via the susceptor 33 and the heat transfer gas on the lower surface of the substrate G.

[0019] The mounting table 3 is provided with lifting pins (not shown) for transferring the substrate G to and from an external transfer device (not shown). The lifting pins vertically penetrate the mounting table 3 and the bottom plate of the processing vessel 1, and protrude and retract from the surface of the mounting table 3.

[0020] A dielectric layer 31 is provided on the upper surface of the susceptor 33. An adsorption electrode 32 made of a metal and extending in the horizontal direction is embedded in the dielectric layer 31. The dielectric layer 31 and the adsorption electrode 32 constitute an electrostatic chuck. The adsorption electrode 32 is connected to a DC power supply 40 via a wiring 41. The DC power supply 40 applies a DC voltage (adsorption voltage) to the adsorption electrode 32 based on a set value input from, for example, the control unit 9. When the adsorption voltage is applied to the adsorption electrode 32, an electrostatic attraction is generated between the adsorption electrode 32 and the substrate G via the dielectric layer 31. As a result, the substrate G is adsorbed and held on the dielectric layer 31. A resistor 42 and a switch 43 for adjusting the adsorption voltage are provided in the wiring 41.

[0021] The plasma generating unit 7 has an inductively coupled antenna 70. The inductively coupled antenna 70 is provided above the processing vessel 1 so as to face the mounting table 3 through the metal window 2. The inductively coupled antenna 70 has a spiral or annular shape. The inductively coupled antenna 70 is stored in an antenna chamber (not shown) provided above the metal window 2. A source power supply 72 is connected to the inductively coupled antenna 70 via a matching box 71. The matching box 71 includes a variable capacitance capacitor. The source power supply 72 supplies a source RF signal (second high frequency) to the inductively coupled antenna 70. This generates an electric field for maintaining a plasma generation state in the processing vessel 1. The source RF signal has a frequency of, for example, 13.56 MHz.

[0022] The plasma generating unit 7 also has a bias power supply 75. The bias power supply 75 is connected to the susceptor 33 via a wiring 73. The bias power supply 75 supplies a bias RF signal (first high frequency) to the susceptor 33. In this embodiment, the generation of plasma can be started (plasma ignition) by capacitive coupling between the metal window 2 and the mounting table 3. In this way, the metal window 2 and the mounting table 3 also function as an upper electrode and a lower electrode in capacitive coupling at the time of plasma ignition. In addition, ions and the like contained in the plasma of the processing gas that is maintained in a generated state in the processing container 1 by the supply of the source RF signal can be drawn into the substrate G placed on the mounting table 3. A matching box 74 for matching the bias RF signal is interposed in the wiring 73. The matching box 74 includes a variable capacitance capacitor. The bias RF signal has a frequency of, for example, 3.2 MHz. Generally, a circuit including a bias power supply and the like is for drawing ions from the generated plasma, and is therefore not included in the "plasma generating unit". However, in this embodiment, since the circuit including the bias power supply has the function of igniting plasma, it is described as constituting part of the "plasma generating unit."

[0023] The control unit 9 controls each part of the plasma processing apparatus. The control unit 9 includes, for example, a computer 90. The computer 90 includes a CPU 91, a storage unit 92, and a communication interface 93. The CPU 91 performs various control operations based on a program stored in the storage unit 92. The storage unit 92 includes at least one memory type selected from a group consisting of auxiliary storage devices such as a RAM, a ROM, a hard disk drive (HDD), and a solid state drive (SSD). The storage unit 92 stores various information used when performing a plasma processing method described later. The various information includes, for example, set values ​​such as an attraction voltage, a power of a source RF signal, a power of a bias RF signal, and a flow rate of a processing gas. The various information includes, for example, preset positions of variable capacitance capacitors of the matching devices 71 and 74. The communication interface 93 may communicate with the plasma processing apparatus via a communication line such as a local area network (LAN).

[0024] [Plasma Treatment Method] With reference to FIG. 2, a plasma processing method according to the embodiment will be described taking as an example a case where plasma processing is performed on a substrate G placed on a mounting table 3 in the plasma processing apparatus shown in FIG.

[0025] First, at time t11, the control unit 9 turns on the switch 43 to apply an adsorption voltage from the DC power supply 40 to the adsorption electrode 32. Also, at time t11, the control unit 9 opens the valve 25 and controls the flow rate adjustment unit 24 to supply the processing gas with the adjusted flow rate from the gas supply source 23 to each gas dispersion chamber 20. Also, at time t11, the control unit 9 controls the exhaust unit 15 to adjust the pressure in the processing container 1 from the pre-processing pressure P1 to the ignition pressure P3. The pre-processing pressure P1 may be a pressure in a state where the exhaust unit 15 is fully exhausted. For example, the pre-processing pressure P1 is a pressure of 1 mTorr (0.13 Pa) or less. The pre-processing pressure P1 may be a predetermined pressure adjusted by the exhaust unit 15. The ignition pressure P3 is a pressure higher than the pre-processing pressure P1 and may be a predetermined pressure adjusted by the exhaust unit 15. From the viewpoint of easily realizing stable plasma ignition regardless of the type of processing gas, the ignition pressure P3 is preferably 15 mTorr to 25 mTorr (2.0 Pa to 3.3 Pa), and more preferably 20 mTorr (2.7 Pa).

[0026] Next, at time t12, the control unit 9 controls the bias power supply 75 to supply a bias RF signal to the susceptor 33 at a first bias power Pb1, and executes a first control to start plasma generation (plasma ignition) between the metal window 2 and the mounting table 3 by capacitive coupling. In the first control, it is preferable that the control unit 9 supplies a bias RF signal to the susceptor 33 in a state in which the position of the variable capacitance capacitor of the matching unit 74 is moved to a preset position for plasma ignition by the bias power supply 75 stored in the storage unit 92. This can shorten the plasma ignition time. The preset position for plasma ignition by the bias power supply 75 is determined by a preliminary experiment or the like, and is stored in advance in the storage unit 92.

[0027] Next, at time t13, the control unit 9 adjusts the pressure inside the processing vessel 1 from the ignition pressure P3 to a processing pressure P2 by controlling the exhaust unit 15. The processing pressure P2 may be a pressure lower than the ignition pressure P3. The processing pressure P2 may be, for example, 5 mTorr to 15 mTorr (0.67 Pa to 2.0 Pa).

[0028] Next, at time t14, the control unit 9 controls the source power supply 72 to supply a source RF signal to the inductively coupled antenna 70 at a first source power Ps1, thereby executing a second control for maintaining a plasma generation state by inductive coupling via the metal window 2. At time t14, the source RF signal is supplied to the inductively coupled antenna 70 while the pressure inside the processing vessel 1 is maintained at processing pressure P2.

[0029] Next, at time t15, the control unit 9 controls the bias power supply 75 to change the bias RF signal from the first bias power Pb1 to the second bias power Pb2, and executes a third control for performing a plasma process on the substrate G placed on the mounting table 3. The second bias power Pb2 ​​is a higher value than the first bias power Pb1. However, depending on the type of plasma process performed on the substrate G, the second bias power Pb2 ​​may be a lower value than the first bias power Pb1. It is preferable that the time t15 is performed after a predetermined time (hereinafter referred to as the "offset time") has elapsed from the time when the source RF signal is supplied to the inductive coupling antenna 70 (time t14). This makes it easier for the bias RF signal to be stabilized at the second bias power Pb2. It is preferable that the offset time is 2 seconds or more.

[0030] After a predetermined time has elapsed from time t15 and the plasma processing performed on the substrate G is completed, the control unit 9 controls the source power supply 72 to stop the supply of the source RF signal to the metal window 2, and controls the bias power supply 75 to stop the supply of the bias RF signal to the susceptor 33. The control unit 9 also closes the valve 25 to stop the supply of the processing gas to each gas dispersion chamber 20, and controls the exhaust unit 15 to reduce the pressure inside the processing vessel 1. Thereafter, the control unit 9 ends the processing.

[0031] Conventionally, when plasma is difficult to ignite, there is a method of igniting plasma by introducing a rare gas that easily ignites plasma, but this may have adverse effects such as degrading electrical characteristics depending on the device formed on the substrate G. According to the plasma processing method according to the embodiment described above, the control unit 9 supplies a bias RF signal to the susceptor 33 while supplying the processing gas into the processing container 1, and ignites plasma by capacitive coupling between the metal window 2 and the mounting table 3. Next, the control unit 9 supplies a source RF signal to the inductive coupling antenna 70, and maintains plasma by inductive coupling via the metal window 2. This makes it possible to improve plasma ignition without using a gas other than the processing gas (e.g., a rare gas). Therefore, the substrate G is not exposed to plasma generated from a gas other than the processing gas. As a result, the influence on the electrical characteristics of the device formed on the substrate G can be reduced.

[0032] In addition, in the plasma processing method according to the embodiment, the control unit 9 may store in the storage unit 92 log information for determining whether or not plasma is ignited by capacitive coupling when the first control is executed. This allows an administrator or the like to determine whether or not plasma is ignited by capacitive coupling when the first control is executed by checking the log information stored in the storage unit 92. The log information may include actual measurement values ​​indicating the state of the bias RF signal, for example, immediately before starting the first control, during execution of the first control, and immediately after the end of the first control. Examples of the actual measurement values ​​indicating the state of the bias RF signal include forward power and reflected power of the bias RF signal, a difference Vpp (Voltage peak to peak) between the maximum voltage and the minimum voltage of the bias RF signal, and an intermediate voltage Vdc (Voltage direct current) of the bias RF signal. In addition, the log information may include a setting value related to the first control, for example, a setting value of the power of the bias RF signal and a setting value of the execution time of the first control.

[0033] In addition, in a multi-step process including a plurality of discharge steps for performing plasma processing on the substrate G placed on the mounting table 3, the plasma processing method according to the embodiment may be performed at least for the first discharge step. That is, at least in the first discharge step, plasma is ignited by capacitive coupling between the metal window 2 and the mounting table 3, and then the plasma is maintained by inductive coupling via the metal window 2. In a multi-step process, if plasma is ignited in the first discharge step, plasma is ignited stably in the second and subsequent discharge steps. In addition, in a multi-step process, the process may start from a discharge step in the middle (e.g., the second) of the plurality of discharge steps. In this case, the plasma processing method according to the embodiment may be performed at least for the discharge step immediately after the start (e.g., the second).

[0034] With reference to Fig. 3, a plasma processing method according to a modified embodiment will be described taking as an example a case where plasma processing is performed on a substrate G placed on a mounting table 3 in the plasma processing apparatus shown in Fig. 1. The plasma processing method according to the modified embodiment differs from the plasma processing method according to the embodiment shown in Fig. 2 in that the pressure inside the processing vessel 1 is adjusted from the ignition pressure P3 to the processing pressure P2 after a source RF signal is supplied to the inductively coupled antenna 70. The following description will focus on the differences from the plasma processing method according to the embodiment shown in Fig. 2.

[0035] First, at time t21, the control unit 9 controls the switch 43 to be on, thereby applying an adsorption voltage from the DC power supply 40 to the adsorption electrode 32. Also, at time t21, the control unit 9 opens the valve 25 and controls the flow rate adjustment unit 24 to supply the processing gas, the flow rate of which is adjusted, from the gas supply source 23 to each gas dispersion chamber 20. Also, at time t21, the control unit 9 controls the exhaust unit 15 to adjust the pressure in the processing vessel 1 from the pre-processing pressure P1 to the ignition pressure P3.

[0036] Next, at time t22, the control unit 9 controls the bias power supply 75 to supply a bias RF signal to the susceptor 33 at a first bias power Pb1, thereby executing a first control to ignite plasma between the metal window 2 and the mounting table 3 by capacitive coupling.

[0037] Next, at time t23, the control unit 9 controls the source power supply 72 to supply a source RF signal to the inductively coupled antenna 70 at a first source power Ps1, thereby executing a second control for maintaining plasma by inductive coupling via the metal window 2. At time t23, the source RF signal is supplied to the inductively coupled antenna 70 while the pressure inside the processing vessel 1 is maintained at the ignition pressure P3.

[0038] Next, at time t24, the control unit 9 controls the bias power supply 75 to change the bias RF signal from the first bias power Pb1 to the second bias power Pb2, and executes a third control to perform plasma processing on the substrate G placed on the mounting table 3.

[0039] Next, at time t25, the control unit 9 adjusts the pressure inside the processing vessel 1 from the ignition pressure P3 to the processing pressure P2 by controlling the exhaust unit 15. The processing pressure P2 may be a pressure lower than the ignition pressure P3.

[0040] After a predetermined time has elapsed from time t25 and the plasma processing of the substrate G is completed, the control unit 9 controls the source power supply 72 to stop the supply of the source RF signal to the metal window 2, and controls the bias power supply 75 to stop the supply of the bias RF signal to the susceptor 33. The control unit 9 also closes the valve 25 to stop the supply of the processing gas to each gas dispersion chamber 20, and controls the exhaust unit 15 to reduce the pressure inside the processing vessel 1. Then, the control unit 9 ends the processing.

[0041] According to the plasma processing method according to the modified example of the embodiment described above, like the plasma processing method according to the embodiment shown in FIG. 2, it is possible to improve plasma ignition performance without using any gas other than the processing gas (e.g., a rare gas).

[0042] In the plasma processing method according to the modified example of the embodiment, the pressure in the processing vessel 1 is adjusted from the ignition pressure P3 to the processing pressure P2 after the bias RF signal is changed to the second bias power Pb2, but the present invention is not limited to this. For example, the pressure in the processing vessel 1 may be adjusted from the ignition pressure P3 to the processing pressure P2 after the source RF signal is supplied to the inductively coupled antenna 70 and before the bias RF signal is changed to the second bias power Pb2.

[0043] [Example] Examples performed to confirm the effects of the embodiment will be described below.

[0044] Example 1 In Example 1, the plasma ignition property was confirmed when the plasma processing method according to the embodiment shown in Figure 2 was performed using the plasma processing apparatus shown in Figure 1. In Example 1, the first bias power Pb1 was set to 0.5 kW, the second bias power Pb2 ​​was set to 2.0 kW, and the first source power Ps1 was set to 7.5 kW. In Example 1, the pre-processing pressure P1 was set to the pressure in the exhaust section 15 in a fully exhausted state, the ignition pressure P3 was set to 20 mTorr (2.7 Pa), and the processing pressure P2 was set to 10 mTorr (1.3 Pa). In Example 1, a mixed gas of CF4 and O2 (CF4 / O2 = 400 sccm / 100 sccm) was used as the processing gas.

[0045] Fig. 4 is a diagram showing plasma ignition performance when the plasma processing method shown in Fig. 2 is performed. In Fig. 4, the horizontal axis indicates time [seconds], the first vertical axis (left axis) indicates power [W], and the second vertical axis (right axis) indicates pressure [mTorr]. In Fig. 4, the thick solid line and the thick dashed line indicate the forward wave power and the reflected wave power of the source RF signal, respectively, the thin solid line and the thin dashed line indicate the forward wave power and the reflected wave power of the bias RF signal, respectively, and the dashed line indicates the pressure inside the processing vessel 1.

[0046] As shown in FIG. 4, it is understood that good ignition performance is obtained in Example 1.

[0047] Example 2 In Example 2, the plasma ignition property was confirmed when the plasma processing method according to the modified example of the embodiment shown in Fig. 3 was performed using the plasma processing apparatus shown in Fig. 1. The power, pressure, and processing gas in Example 2 were the same as those in Example 1, respectively.

[0048] Fig. 5 is a diagram showing plasma ignition performance when the plasma processing method shown in Fig. 3 is performed. In Fig. 5, the horizontal axis indicates time [seconds], the first vertical axis (left axis) indicates power [W], and the second vertical axis (right axis) indicates pressure [mTorr]. In Fig. 5, the thick solid line and the thick dashed line indicate the forward wave power and the reflected wave power of the source RF signal, respectively, the thin solid line and the thin dashed line indicate the forward wave power and the reflected wave power of the bias RF signal, respectively, and the dashed line indicates the pressure inside the processing vessel 1.

[0049] As shown in FIG. 5, it is understood that, like Example 1, good ignition performance is obtained in Example 2 as well.

[0050] Example 3 In Example 3, the plasma ignition performance was confirmed when the offset time until the bias power change was changed. In Example 3, the plasma processing method according to the embodiment shown in FIG. 2 was carried out using the plasma processing apparatus shown in FIG. 1. In Example 3, the offset time until the bias power change was set to 1 second, 2 seconds, and 3 seconds. The power, pressure, and processing gas in Example 3 were the same as those in Example 1, respectively.

[0051] 6 to 8 are diagrams showing the plasma ignition performance when the offset time until the bias power change is changed in the plasma processing method shown in FIG. 2. FIGS. 6, 7, and 8 show the results when the offset time is set to 1 second, 2 seconds, and 3 seconds, respectively. In FIGS. 6 to 8, the horizontal axis indicates time [seconds], the first vertical axis (left axis) indicates power [W], and the second vertical axis (right axis) indicates pressure [mTorr]. In FIGS. 6 to 8, the thick solid line indicates the forward wave power of the source RF signal, the thin solid line indicates the forward wave power of the bias RF signal, and the dashed dotted line indicates the pressure inside the processing vessel 1.

[0052] As shown in Fig. 6, when the offset time until the bias power change is set to 1 second, the forward wave power of the source RF signal becomes almost zero immediately after the bias RF signal starts to change from the first bias power Pb1 to the second bias power Pb2, and the plasma is misfired. At this time, the bias RF signal is also cut off before reaching 2.0 kW set as the second bias power Pb2. As shown in Figs. 7 and 8, when the offset time until the bias power change is set to 2 and 3 seconds, good ignition performance is obtained. From these results, it is considered preferable to set the offset time until the bias power change to 2 seconds or more.

[0053] Example 4 In Example 4, the plasma ignition performance was confirmed when the processing gas was changed. In Example 4, the plasma processing method according to the embodiment shown in FIG. 2 was carried out using the plasma processing apparatus shown in FIG. 1. In Example 4, the processing gas was a mixture gas of CF4 and O2 (CF4 / O2), O 2、 A mixed gas of CF4 and Ar (CF4 / Ar) was used.

[0054] Under the condition of using CF4 / O2 as the process gas, the first bias power Pb1 was set to 0.5 kW, the second bias power Pb2 ​​was set to 2.0 kW, and the first source power Ps1 was set to 7.5 kW. In addition, the pre-processing pressure P1 was set to the pressure in the exhaust section 15 exhausted state, the ignition pressure P3 was set to 20 mTorr (2.7 Pa), and the process pressure P2 was set to 10 mTorr (1.3 Pa).

[0055] Under the condition where O2 was used as the processing gas, the first bias power Pb1 was set to 0.5 kW, the second bias power Pb2 ​​was set to 0.15 kW, and the first source power Ps1 was set to 5.0 kW. In addition, the pre-processing pressure P1 was set to the pressure in the exhaust section 15 exhausted state, the ignition pressure P3 was set to 20 mTorr (2.7 Pa), and the processing pressure P2 was set to 30 mTorr (4.0 Pa).

[0056] Under the condition of using CF4 / Ar as the process gas, the first bias power Pb1 was set to 0.5 kW, the second bias power Pb2 ​​was set to 5.0 kW, and the first source power Ps1 was set to 5.0 kW. In addition, the pre-processing pressure P1 was set to the pressure in the exhaust section 15 exhausted state, the ignition pressure P3 was set to 20 mTorr (2.7 Pa), and the process pressure P2 was set to 10 mTorr (1.3 Pa).

[0057] 9 to 11 are diagrams showing plasma ignition properties when the processing gas is changed in the plasma processing method shown in FIG. 2. FIG. 9, FIG. 10, and FIG. 11 respectively show the results when CF4 / O2, O2, and CF4 / Ar were used as the processing gas. In FIG. 9 to FIG. 11, the horizontal axis indicates time [seconds], the first vertical axis (left axis) indicates power [W], and the second vertical axis (right axis) indicates pressure [mTorr]. In FIG. 9 to FIG. 11, the thick solid line indicates the forward wave power of the source RF signal, the thin solid line indicates the forward wave power of the bias RF signal, and the dashed dotted line indicates the pressure inside the processing vessel 1.

[0058] As shown in Figs. 9 to 11, it is apparent that good ignition performance was obtained when any of the processing gases was used.

[0059] Example 5 In Example 5, the plasma ignition property when a multi-step process was performed was confirmed. In Example 5, the multi-step process included four discharge steps. In Example 5, in the first discharge step, the plasma processing method according to the embodiment shown in FIG. 2 was performed using the plasma processing apparatus shown in FIG. 1. In the second to fourth discharge steps, a source RF signal was supplied to the inductive coupling antenna 70 and a bias RF signal was supplied to the susceptor 33 at the same time, without performing plasma ignition by capacitive coupling between the metal window 2 and the mounting table 3.

[0060] Fig. 12 is a diagram showing the plasma ignition performance when a multi-step process is performed. In Fig. 12, the horizontal axis indicates time [seconds], the first vertical axis (left axis) indicates power [W], and the second vertical axis (right axis) indicates pressure [mTorr]. In Fig. 12, the thick solid line indicates the forward wave power of the source RF signal, the thin solid line indicates the forward wave power of the bias RF signal, and the dashed dotted line indicates the pressure inside the process vessel 1.

[0061] 12, it can be seen that good ignition performance was obtained in all of the first to fourth discharge steps. This result shows that in a multi-step process, if plasma ignition is achieved in the first discharge step, stable plasma ignition is achieved in the second and subsequent discharge steps even without implementing the plasma processing method according to the embodiment.

[0062] Example 6 In Example 6, the influence of the plasma ignited by capacitive coupling on the film formed on the surface of the substrate G was confirmed. In Example 6, the plasma processing apparatus shown in FIG. 1 was used, and only the first control in the plasma processing method according to the embodiment shown in FIG. 2 was performed. In Example 6, the substrate G, on whose surface a silicon oxide film and a silicon nitride film were formed as the target film to be evaluated, was subjected to processing by the first control, and the thickness of the target film before and after the processing was measured to calculate the amount of scraping of the target film. In Example 6, the first bias power Pb1 was set to 0.5 kW, the ignition pressure P3 was set to 20 mTorr (2.7 Pa), and the processing time was set to 5 seconds. In Example 6, a mixed gas of CF4 and O2 (CF4 / O2=400 sccm / 100 sccm) was used as the processing gas.

[0063] Fig. 13 is a diagram showing the amount of removal of the target film that was processed by the first control. In Fig. 13, "0 Å" means that the amount of removal was below the measurement limit of the film thickness gauge, and includes cases where the target film was not removed at all and cases where the target film was hardly removed at all.

[0064] As shown in Fig. 13, the amount of removal of the silicon oxide film and silicon nitride film processed by the first control is 0 Å. This result shows that the silicon oxide film and silicon nitride film are not removed at all or are hardly removed at all even when exposed to the plasma generated by ignition through capacitive coupling. In other words, it was shown that the plasma ignited through capacitive coupling has almost no effect on the target film.

[0065] In the above embodiment, the first bias power Pb1 is an example of the first power, the first source power Ps1 is an example of the second power, and the second bias power Pb2 ​​is an example of the third power. The ignition pressure P3 is an example of the first pressure, and the process pressure P2 is an example of the second pressure.

[0066] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0067] 1 Processing vessel 2 Metal Windows 3. Placement table 9. Control Unit G board

Claims

1. a processing vessel for performing plasma processing on a substrate using plasma therein; a mounting table disposed inside the processing chamber, the mounting table also serving as a lower electrode and on which the substrate is placed; a metal window that is formed on a ceiling of the processing vessel while maintaining electrical insulation from the processing vessel and is connected to ground; an inductively coupled antenna disposed opposite the mounting table via the metal window and electrically insulated from the metal window; A control unit for controlling the plasma processing; Equipped with The control unit a first control for supplying a first high frequency wave with a first power to the mounting table and igniting the plasma by capacitive coupling between the metal window and the mounting table; a second control for supplying a second high frequency wave at a second power to the inductively coupled antenna and maintaining the plasma by inductive coupling via the metal window; and executing a third control of changing the first high frequency power to a third power greater than the first power and performing the plasma processing on the substrate placed on the mounting table. Plasma processing equipment.

2. In the third control, the change of the first radio frequency to the third power is performed after a predetermined time has elapsed from the time when the second radio frequency is supplied to the inductive coupling antenna at the second power. The plasma processing apparatus according to claim 1 .

3. a first pressure in the processing vessel during the first control is higher than a second pressure in the processing vessel during the plasma processing of the substrate; 3. The plasma processing apparatus according to claim 1 or 2.

4. In the second control, the second high frequency wave is changed from the first pressure to the second pressure before being supplied to the inductively coupled antenna at the second power. The plasma processing apparatus according to claim 3 .

5. the metal window is composed of a plurality of divided windows, each of the plurality of divided windows being connected to ground via an impedance adjustment circuit; The plasma processing apparatus according to claim 1 .

6. A processing gas is supplied into the processing chamber, the plasma is ignited from the processing gas in the first control, and the plasma is maintained in the third control. The plasma processing apparatus according to claim 1 .

7. a processing vessel for performing plasma processing on a substrate using plasma therein; a mounting table disposed inside the processing chamber, the mounting table also serving as a lower electrode and on which the substrate is placed; a metal window that is formed on a ceiling of the processing vessel while maintaining electrical insulation from the processing vessel and is connected to ground; an inductively coupled antenna disposed opposite the mounting table via the metal window and electrically insulated from the metal window; In a plasma processing apparatus comprising: supplying a first high frequency wave with a first power to the mounting table, and igniting the plasma by capacitive coupling between the metal window and the mounting table; supplying a second high frequency wave at a second power to the inductively coupled antenna and maintaining the plasma by inductive coupling through the metal window; changing the first high frequency power to a third power greater than the first power, and performing the plasma processing on the substrate placed on the mounting table; The plasma processing method comprises:

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