Plasma processing method and plasma processing apparatus

Abstract

A plasma processing method is a plasma processing method using a plasma processing apparatus, the plasma processing method including: acquiring parameters including a first initial power value, an initial power application time, and an output suppression ratio; acquiring a processing process including a process setting power value as a second initial power value; and determining an initial turn-on power to the plasma excitation antenna from among the first initial power value and the second initial power value, and determining the initial turn-on power to the plasma excitation antenna when the first initial power value is determined to be the initial turn-on power. The plasma processing method includes: supplying the determined initial ON power to the plasma excitation antenna for a time length that is at least the initial power application time; and gradually increasing the output of the high-frequency power supplied to the plasma excitation antenna from the initial turn-on power to the process setting power value.

Description

Technical Field

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

[0002] Patent document 1 discloses a plasma processing device, which includes at least one of a matching device control unit, a magnetic field setting unit, and a pressure control unit for facilitating the ignition of plasma and shortening the ignition time. According to the device described in Patent document 1, the time from the turn-on of high-frequency power to the ignition of plasma (ignition delay time) is shortened by the above-mentioned units.

[0003] In addition, a method for detecting the state of an inductively coupled plasma source is disclosed in Patent Document 2. The method described in Patent Document 2 enables accurate detection of the change of the plasma source from capacitively coupled plasma to inductively coupled plasma.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2008-060304

[0007] Patent Document 2: Japanese Patent Application Publication No. 2021-157946 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The technology according to the present disclosure appropriately suppresses the occurrence of abnormal discharge in an RF circuit during plasma processing.

[0010] Solutions for solving problems

[0011] One embodiment of the present disclosure is a plasma processing method, which is a plasma processing method using a plasma processing device, and the plasma processing method includes the following steps: obtaining parameters including a first initial power value, an initial power application time, and an output suppression ratio; obtaining a processing process including a process setting power value as a second initial power value; and determining an initial connection power for a plasma excitation antenna from one of the first initial power value and the second initial power value. When the first initial power value is determined as the initial connection power, the plasma processing method includes the following steps: supplying the determined initial connection power to the plasma excitation antenna for a time length at least longer than the initial power application time; and gradually increasing the output of the high-frequency power supplied to the plasma excitation antenna from the initial connection power to the process setting power value.

[0012] Effects of the Invention

[0013] According to the present disclosure, it is possible to appropriately suppress the occurrence of abnormal discharge in an RF circuit during plasma processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a graph showing the change with time of the Vpp value when plasma is generated.

[0015] Figure 2 It is a top view showing an example of the structure of a vacuum processing system.

[0016] Figure 3 It is a longitudinal sectional view showing an example of the structure of the plasma processing apparatus according to the present embodiment.

[0017] Figure 4 1 is a flowchart showing main steps of wafer processing according to the present embodiment.

[0018] Figure 5 3 is a graph showing the relationship between the Vpp value and the applied power when plasma is not ignited.

[0019] Figure 6 is a graph showing the relationship between the transition power and the turn-on power for generating an inductively coupled plasma.

[0020] Figure 7 : is a graph showing an example of a change over time of the Vpp value during the plasma processing according to the present embodiment.

[0021] Figure 8 : is a graph showing an example of a change over time of the Vpp value during the plasma processing according to the present embodiment.

[0022] Fig. 9 : is a graph showing an example of a change over time of the Vpp value during the plasma processing according to the present embodiment. DETAILED DESCRIPTION

[0023] In the manufacturing process of semiconductor devices, etc., plasma processing such as etching is performed on a semiconductor substrate (hereinafter, simply referred to as a "substrate") using plasma. As an example, in the plasma processing, an RF (Radio Frequency) signal is supplied to a coil disposed above a processing container for accommodating the substrate as a processing target, thereby generating an inductively coupled plasma (ICP) in the processing container.

[0024] In addition, in such plasma processing, an interlock control is performed to stop the supply of RF signal when Vpp (Voltpeak to peak) above a predetermined threshold is detected to suppress the generation of abnormal discharge in the RF circuit. However, due to the influence of high power in recent processes, it is possible that the ignition delay (see Figure 1 ) in the case where Vpp exceeds the threshold and abnormal discharge occurs in the RF circuit.

[0025] In addition, it is known that when an inductively coupled plasma is generated in a processing container, a capacitively coupled plasma (CCP) is sometimes converted to an inductively coupled plasma in the processing container. However, the conversion of the plasma mode from the capacitively coupled plasma to the inductively coupled plasma sometimes requires a large current, and abnormal discharge may also occur during the conversion of the plasma mode.

[0026] Furthermore, it is known that the resistance value of capacitively coupled plasma is larger than that of inductively coupled plasma. Therefore, even when a low-power RF signal is supplied to the coil when plasma processing is performed under the generation of inductively coupled plasma, a large current may flow in the RF circuit under the generation of capacitively coupled plasma before the plasma mode transition (see Figure 1 ), from this point of view, abnormal discharge may also occur.

[0027] Furthermore, the above-mentioned Patent Documents 1 and 2 disclose respectively that an ignition delay occurs during plasma processing and that the plasma mode changes from capacitively coupled plasma to inductively coupled plasma, but neither discloses that abnormal discharge occurs as a result, nor suggests that abnormal discharge occurs.

[0028] The technology disclosed herein is accomplished in view of the above circumstances, and appropriately suppresses the generation of abnormal discharge in the RF circuit during plasma processing. The plasma processing method and the plasma processing device for implementing the plasma processing method according to the present embodiment are described below with reference to the accompanying drawings. In addition, in this specification and the accompanying drawings, the same reference numerals are given to elements having substantially the same functional structure, thereby omitting repeated descriptions.

[0029] <Vacuum treatment system>

[0030] First, the configuration of a vacuum processing system according to one embodiment will be described.

[0031] like Figure 2 As shown, the vacuum processing system 1 has a structure in which an atmosphere part 10 and a decompression part 30 are integrally connected via a load lock module 20 .

[0032] The atmospheric section 10 includes: a loading port 11, which carries a front-opening wafer transfer box F capable of storing multiple substrates W; a cooling storage device 12, which cools the substrate W after being processed in the decompression section 30; an aligner module 13, which adjusts the horizontal orientation of the substrate W; and a loader module 14, which is used to transport the substrate W in the atmospheric section 10.

[0033] The loader module 14 is composed of a housing with a rectangular interior, and the interior of the housing is maintained at atmospheric pressure. A plurality of, for example, three, loading ports 11 are arranged in parallel on one side of the long side of the housing of the loader module 14. A plurality of, for example, two, loading interlock modules 20 are arranged in parallel on the other side of the long side of the housing of the loader module 14. A cooling storage device 12 is arranged on one side of the short side of the housing of the loader module 14. An aligner module 13 is arranged on the other side of the short side of the housing of the loader module 14.

[0034] In addition, a wafer transfer mechanism (not shown) for transferring the substrate W is provided inside the loader module 14. The wafer transfer mechanism has a transfer arm (not shown) for holding and moving the substrate W, and is configured to transfer the substrate W to the front-opening wafer pod F placed on the load port 11, the cooling storage device 12, the aligner module 13, and each load lock module 20.

[0035] Each load lock module 20 temporarily holds a substrate W so as to transfer the substrate W conveyed from the loader module 14 of the atmosphere section 10 to the transfer module 31 described later of the decompression section 30. The load lock module 20 has a plurality of, for example, two storage cabinets (not shown) inside, thereby simultaneously holding two substrates W inside. In addition, each load lock module 20 has a gate valve (not shown) for ensuring air tightness for the loader module 14 and the transfer module 31 described later. Through the gate valve, the air tightness between the loader module 14 and the transfer module 31 and the loader module 14 can be ensured, and the loader module 14 and the transfer module 31 and the loader module 14 can be mutually connected. In addition, a gas inlet (not shown) and a gas exhaust (not shown) are connected to each load lock module 20, so as to be able to switch the interior of each load lock module 20 between an atmospheric pressure atmosphere and a decompression atmosphere. That is, the load lock module 20 is configured to appropriately transfer the substrate W between the atmospheric pressure section 10 and the reduced pressure section 30 .

[0036] The decompression unit 30 includes a transfer module 31 that simultaneously transfers two substrates W, and a plasma processing device 32 that performs a desired plasma processing on the substrates W transferred from the transfer module 31. The interiors of the transfer module 31 and the plasma processing device 32 are each maintained in a decompression atmosphere. In addition, a plurality of, for example, six, plasma processing devices 32 are provided relative to the transfer module 31.

[0037] The transfer module 31 is composed of a housing having a rectangular interior, and as described above, the transfer module 31 is connected to each load lock module 20 via a gate valve. The transfer module 31 transfers the substrate W loaded into the load lock module 20 to one or more plasma processing devices 32 for plasma processing, and then carries the substrate out to the atmosphere section 10 via the load lock module 20.

[0038] A wafer transfer mechanism 40 for transferring the substrate W is provided inside the transfer module 31. The wafer transfer mechanism 40 includes transfer arms 41, 41 for holding and moving two substrates W in a longitudinal arrangement, a rotating table 42 for rotatably supporting the transfer arms 41, 41, and a rotating stage 43 for carrying the rotating table 42. In addition, a guide rail 44 extending in the longitudinal direction of the transfer module 31 is provided inside the transfer module 31. The rotating stage 43 is provided on the guide rail 44 and is configured to enable the wafer transfer mechanism 40 to move along the guide rail 44.

[0039] The plasma processing device 32 has a gate valve 32a (see Figure 3 ). Through the gate valve 32a, the airtightness between the transfer module 31 and the plasma processing device 32 can be ensured and the transfer module 31 and the plasma processing device 32 can be connected to each other.

[0040] The plasma processing device 32 is provided with two work tables 90, 90 for placing two substrates W in a horizontal arrangement. The plasma processing device 32 places the substrates W in an arranged manner on the work tables 90, 90, and performs arbitrary plasma processing on the two substrates W simultaneously. The detailed structure of the plasma processing device 32 will be described later.

[0041] The above vacuum processing system 1 is provided with a control device 50. The control device 50 is, for example, a computer having a CPU, a memory, etc., and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the substrate W in the vacuum processing system 1. In addition, the program storage unit also stores a program for controlling the operation of the drive system of the various processing modules, the conveying mechanism, etc. mentioned above to perform the timing control of the wafer conveyance described later in the vacuum processing system 1. In addition, the above program can also be recorded in a computer-readable storage medium H, and installed in the control device 50 from the storage medium H. In addition, the above storage medium H can be transient or non-transient.

[0042] <Plasma processing device>

[0043] Next, the structure of the above-mentioned plasma processing apparatus 32 will be described in detail. Figure 3 3 is a longitudinal sectional view showing an outline of the structure of the plasma processing device 32. Figure 2 As shown, inside the plasma processing device 32, two work tables 90, 90 are arranged in a horizontal direction, but Figure 3 In order to suppress the complexity of the illustration, only one stage 90 is shown in the figure. In other words, a longitudinal cross-sectional view viewed from one side surface constituting a short side of the plasma processing device 32 is shown.

[0044] like Figure 3 As shown, the plasma processing apparatus 32 includes a closed processing container 60 for accommodating substrates W. The processing container 60 is made of, for example, aluminum or an aluminum alloy, and the upper end of the processing container 60 is open, and the upper end of the processing container 60 is blocked by a cover 60a serving as a top. A loading and unloading port 60b for substrates W is provided on the side of the processing container 60, and the loading and unloading port 60b is configured to be openable and closable by the gate valve 32a described above.

[0045] The interior of the processing container 60 is partitioned into an upper plasma generation space P and a lower processing space S by a partition plate 61. The plasma generation space P is a space for generating plasma, and the processing space S is a space for performing plasma processing on a substrate W.

[0046] The partition plate 61 has at least two plate-like members 62 and 63, which are arranged to overlap with each other from the plasma generation space P toward the processing space S at a distance. The plate-like members 62 and 63 respectively have slits 62a and 63a formed to penetrate in the overlapping direction. Moreover, the slits 62a and 63a are arranged in a manner that does not overlap when viewed from above, so that the partition plate 61 functions as a so-called ion trap that suppresses ions in the plasma from passing through the processing space S when plasma is generated in the plasma generation space P. More specifically, by forming a maze structure in which the slits 62a and 63a are arranged in a manner that does not overlap, the movement of ions moving anisotropically is prevented, while on the other hand, free radicals moving isotropically are allowed to pass through.

[0047] The plasma generating space P includes a gas supply unit 70 for supplying a processing gas into the processing container 60 , and a plasma generating unit 80 for converting the processing gas supplied into the processing container 60 into plasma.

[0048] The gas supply unit 70 is connected to a plurality of gas supply sources (not shown) to supply desired processing gas corresponding to the purpose of plasma processing of the substrate W into the processing container 60. As an example, the processing gas supplied to the processing container 60 may be a mixed gas including an oxygen-containing gas such as O2 gas and a dilution gas such as Ar gas.

[0049] In addition, the gas supply unit 70 is provided with a flow rate regulator (not shown) for regulating the supply amount of the processing gas to the plasma generation space P. The flow rate regulator includes, for example, an on-off valve and a mass flow controller.

[0050] The plasma generating unit 80 is configured as an inductive coupling type device using an RF antenna. The cover 60a of the processing container 60 is formed of, for example, a quartz plate and is configured as a dielectric window. An RF antenna 81 for generating inductively coupled plasma in the plasma generating space P of the processing container 60 is formed above the cover 60a. The RF antenna 81 is connected to a high-frequency power source 83 that outputs a high-frequency power of a fixed frequency (for example, 13.56 MHz) suitable for the generation of plasma at an arbitrary output value via a matching device 82 having a matching circuit for matching the impedance of the power supply side and the load side. In addition, two RF antennas 81 are provided corresponding to two workbenches 90 described later disposed inside the processing space S, respectively.

[0051] Two workbenches 90, 90 are arranged inside the processing space S (as described above). Figure 3The two work tables 90, 90 respectively carry one substrate W in a horizontal state. The work table 90 has a roughly cylindrical shape, and has an upper table 91 for carrying the substrate W and a lower table 92 for supporting the upper table 91. A temperature regulating mechanism 93 for regulating the temperature of the substrate W is provided inside the upper table 91. In addition, the work table 90 is raised and lowered by a lifting mechanism 94. The lifting mechanism 94 is arranged outside the processing container 60, and the lifting mechanism 94 has an actuator and the like for lifting and lowering the two work tables 90 as a whole. In addition, on the work table 90, a plurality of lifting pins (not shown) used when carrying the substrate W in and out of the processing container 60 are provided in a manner that they can be freely protruded and retracted relative to the upper surface of the upper table 91.

[0052] An exhaust unit 100 is provided at the bottom of the processing container 60. The exhaust unit 100 is connected to an exhaust mechanism (not shown) such as a vacuum pump via an exhaust pipe connected to the processing space S. In addition, an automatic pressure control valve (APC) is provided in the exhaust pipe. The pressure in the processing container 60 is controlled by these exhaust mechanisms and the automatic pressure control valve.

[0053] Furthermore, the operation of the plasma processing device 32 can be controlled by the control device 50. In other words, the control device 50 may store a program for controlling the processing of the substrate W in the plasma processing device 32. However, the control device for controlling the operation of the plasma processing device 32 does not necessarily need to be the control device 50 provided outside the plasma processing device 32. For example, the operation of the plasma processing device 32 may be controlled by a control unit (not shown) provided independently of the plasma processing device 32.

[0054] <Plasma treatment method>

[0055] The vacuum processing system 1 and the plasma processing apparatus 32 according to the present embodiment are configured as described above. Next, plasma processing of the substrate W using the plasma processing apparatus 32 will be described.

[0056] When the substrate W is subjected to plasma processing, first, parameters related to the plasma processing are acquired and set ( Figure 4 The parameters set in step St1 may be input by an operator during the plasma processing of the substrate W, or may be output to the control device 50 in advance.

[0057] The parameters set in step St1 include, for example, the initial power application time of the plasma processing device 32, the interlock value of Vpp in the plasma processing device 32, the initial turn-on value of the high-frequency power supplied to the RF antenna 81 during plasma processing (hereinafter referred to as "parameter initial power value"), and the output suppression ratio described later.

[0058] The initial power application time is the time for applying high frequency power at the initial setting value to the RF antenna 81. Figure 1 The “ignition delay” refers to the time from when high-frequency power is turned on to the RF antenna 81 to when plasma is actually generated in the plasma generating space P (ignition).

[0059] The interlock value of Vpp (hereinafter referred to as "VppI / L set value") is a set value (Vpp value) when the supply of the RF signal is stopped by the interlock control as described above, and is a threshold value for suppressing the occurrence of abnormal discharge during plasma processing.

[0060] The parameter initial power value as the first initial power value is based on, for example, Figure 5 The relationship between the "power supplied to the RF antenna 81" and the "Vpp value when the plasma is not ignited (in the ignition delay time)" shown in FIG. 1 and the VppI / L setting value described above is determined. That is, in the plasma processing device 32, after the high-frequency power is supplied to the RF antenna 81, before the inductively coupled plasma is generated, the plasma is sequentially transitioned to the non-ignited state and the state of generating the capacitively coupled plasma. Furthermore, during the period until the inductively coupled plasma is generated, the Vpp value is as large as Figure 1 The figure shows an unignited state of the plasma, and therefore at least when the plasma is unignited, the parameter initial power value of the high-frequency power supplied to the RF antenna 81 is determined to be a value smaller than the VppI / L setting value so as to prevent the interlock function from operating and abnormal discharge from occurring.

[0061] Specifically, for example, when the VppI / L setting value (threshold) is 3500V, if referring to Figure 5 , the Vpp value becomes 3500V when the connected power is about 550W, so the parameter initial power value is set to less than 550W.

[0062] When the parameters related to the plasma processing are acquired and set, the processing recipe of the plasma processing performed on the substrate W in the plasma processing device 32 is acquired. Figure 4 The plasma processing recipe is assigned to each of the plurality of substrates W to be processed in the plasma processing apparatus 32.

[0063] The processing sequence acquired in step St2 includes, for example, the type of plasma processing performed on the substrate W, the set value of the high-frequency power supplied to the RF antenna 81 during the plasma processing (hereinafter referred to as the "process set power value"), the processing time, and the control cycle described later.

[0064] The process setting power value as the second initial power value is an on-value of the high frequency power supplied to the RF antenna 81 when the plasma processing is actually performed on the substrate W, and is at least Figure 6 In other words, the power is set to a value capable of generating an inductively coupled plasma for performing a plasma treatment on the substrate W.

[0065] In the plasma processing apparatus 32, as described above, high frequency power is supplied to the RF antenna 81 to generate inductively coupled plasma in the plasma generation space P, thereby processing the substrate W. However, when the high frequency power supplied to the RF antenna 81 is less than the conversion power, plasma may not be generated in the plasma generation space P, or the capacitively coupled plasma may not be converted into the inductively coupled plasma, and the plasma processing may not be performed on the substrate W. In addition, in such a state that plasma cannot be generated in the plasma generation space P (no ignition), or in a state where capacitively coupled plasma is generated, as shown in FIG. Figure 1 As shown, compared with the state where inductively coupled plasma is generated, a large current may flow in the RF circuit, that is, the risk of abnormal discharge generation increases.

[0066] Therefore, during the plasma treatment of the substrate W, Figure 6 The process setting power value supplied to the RF antenna 81 is set to a value equal to or greater than the transition power shown, thereby appropriately generating inductively coupled plasma by supplying the process setting power value to the RF antenna 81, thereby appropriately performing plasma processing on the substrate W.

[0067] In addition, the recipe setting power value is set so that the Vpp value measured by supplying high-frequency power at the recipe setting power value becomes a value at least smaller than the above-mentioned VppI / L setting value.

[0068] Specifically, for example, when the VppI / L setting value (threshold) is 3500V, if referring to Figure 5 , the Vpp value is 3500V when the connected power is about 550W, so the value above the conversion power and less than 550W ( Figure 6 The process setting power value is set on the right side of the thick line and on the left side of the single-dash line).

[0069] When the plasma processing recipe is obtained, the plasma processing of the substrate W in the plasma processing device 32 is started ( Figure 4 Step St3).

[0070] When the substrate W is subjected to plasma processing, first, the substrate W to be processed is placed on the workbench 90 in the processing space S. The substrate W to be processed is taken out from the front-opening FOUP F placed on the load port 11 by a wafer transfer mechanism (not shown), and after its horizontal orientation is adjusted in the aligner module 13, it is carried into the plasma processing apparatus 32 via the load lock module 20 and the wafer transfer mechanism 40 and placed on the workbench 90.

[0071] Furthermore, as described above, the processing recipe of the plasma processing performed in the plasma processing apparatus 32 is allocated to the substrate W as the processing target.

[0072] When the substrate W is placed on the stage 90, a processing gas ( Figure 4 Step St3-1), and high-frequency power is supplied to the RF antenna 81 to start the generation of plasma in the plasma generation space P.

[0073] Here, during the plasma treatment of the substrate W, as described above, before the inductively coupled plasma (ICP) for plasma treatment is generated, a transition to a plasma unignition state and a capacitively coupled plasma (CCP) generation state is sequentially performed. At this time, during the plasma unignition state and during the capacitively coupled plasma generation, as shown in FIG. Figure 1 As shown, a larger current tends to flow through the RF circuit compared to when the inductively coupled plasma is generated, so there is a high risk of abnormal discharge occurring due to the supply of high-frequency power.

[0074] Therefore, in the plasma processing according to the present embodiment, the high frequency power (initial power-on value) supplied to the RF antenna 81 at the start of plasma generation is determined to be the lower power value of the parameter initial power value set in step St1 and the process setting power value acquired in step St2. In other words, at the same time as the supply of the processing gas to the plasma generation space P in step St3-1, the lower power selected from the parameter initial power value and the process setting power value is supplied to the RF antenna 81 as the initial power-on power ( Figure 4 Step St3-2).

[0075] As described above, the parameter initial power value set in step St1 is set to a value lower than the VppI / L setting value so as not to cause the interlock function to operate and abnormal discharge to occur. Therefore, in this step St3-2, by supplying high-frequency power at a power at least lower than the parameter initial power value, the generation of abnormal discharge when the plasma is not ignited is suppressed.

[0076] In addition, by selecting the initial turn-on power from the lower value between the parameter initial power value and the process setting power value in this way, even if the operator inputs an incorrect process setting power value, for example, a large current flowing in the RF circuit based on the erroneous process input is suppressed, and plasma processing can be started based on the parameter initial power value that does not cause the interlock function to operate or abnormal discharge to occur.

[0077] In addition, during the plasma processing according to the present embodiment, the high frequency power is continuously supplied at the initial power value (parameter initial power value or process setting power value) determined in step St3-2 for a time period at least equal to or longer than the ignition delay time set in step St1. Figure 4 Step St3-3).

[0078] As described later, in the plasma processing according to the present embodiment, when the parameter initial power value is set to the initial power value in step St3-2, the output of the high frequency power supplied to the RF antenna 81 is gradually increased from the initial power value to the above-mentioned process setting power value. At this time, if the output of the high frequency power is increased (increased in power) when the plasma is not ignited, a large current may flow in the RF circuit, causing the interlock function to operate and abnormal discharge to occur.

[0079] Therefore, in this embodiment, the initial power value of the high-frequency power is maintained for a time period longer than the initial power application time set in step St1. More specifically, the initial power value of the high-frequency power is maintained until at least plasma is generated in the plasma generating space P, thereby suppressing the occurrence of abnormal discharge when the plasma is not ignited.

[0080] In addition, whether capacitively coupled plasma is generated in the plasma generation space P can be determined by, for example, measuring the Vpp value or current value of the high frequency power supplied to the RF antenna 81 over time. Figure 1 As shown in , the Vpp value measured when the plasma is not ignited is higher than the Vpp value measured when the capacitively coupled plasma is generated. This is because, when the capacitively coupled plasma is generated in the plasma generation space P, resistance is generated in the plasma, and the high-frequency power supplied to the RF antenna 81 is consumed here. Therefore, in the plasma processing involved in this embodiment, when the change in the Vpp measurement value is detected, it can be determined that the plasma generation space P has changed from the unignited plasma state to the capacitively coupled plasma generation state.

[0081] Moreover, in the plasma processing involved in the present embodiment, it can also be set that, in addition to the above-mentioned initial power application time, the generation of plasma is also judged based on the time-dependent change of the Vpp value (current value), and the subsequent plasma processing steps are entered at the moment when the risk of abnormal discharge is reduced.

[0082] When the initial power value is continuously supplied for a time period longer than the initial power application time to generate capacitively coupled plasma in the plasma generation space P, then inductively coupled plasma ( Figure 4 In other words, the capacitively coupled plasma generated in the plasma generating space P is transformed into the inductively coupled plasma.

[0083] Here, in step St3-2, when the process setting power value is selected as the initial turn-on power supplied to the RF antenna 81, that is, when the process setting power value is smaller than the parameter initial power value, high-frequency power is continuously supplied to the RF antenna 81 at the process setting power value.

[0084] As mentioned above, the process sets the power value to Figure 6 Therefore, by continuously supplying high frequency power at this process setting power value, the density of the capacitively coupled plasma in the plasma generating space P increases, thereby generating inductively coupled plasma (step St3-4).

[0085] Furthermore, as described above, the recipe setting power value is set to a value smaller than the VppI / L setting value set in step St1 , so that when high-frequency power is supplied at the recipe setting power value, the occurrence of abnormal discharge is suppressed.

[0086] On the other hand, in step St3-2, when the parameter initial power value is selected as the initial power supplied to the RF antenna 81, that is, when the parameter initial power value is smaller than the process setting power value, the output of the high frequency power supplied to the RF antenna 81 is gradually increased from the parameter initial power value to the process setting power value. In other words, the parameter initial power value as the initial power is gradually increased to a value at which the inductively coupled plasma for performing plasma processing on the substrate W can be generated.

[0087] Specifically, the output of high frequency power supplied to the RF antenna 81 is increased at each control cycle set in step St1 based on the following equation (1). The control cycle is set to 100 msec in one example, but the value of the control cycle is not limited thereto and can be set arbitrarily.

[0088] Next set power = current set power × output suppression ratio × VppI / L set value / Vpp current value…(1)

[0089] Among them, next set power: represents the power [W] of the high-frequency power supplied to the RF antenna 81 in the next control cycle, current set power: represents the power [W] of the high-frequency power supplied to the RF antenna 81 in the current control cycle, output suppression ratio: represents the coefficient (<1.0) that determines the power change amount until the process set power value as the set power, VppI / L set value: represents the interlock value of Vpp in the plasma processing device 32, and Vpp current value: represents the Vpp value measured when the high-frequency power is supplied with the current set power.

[0090] In addition, as described above, the output suppression ratio in formula (1) is a coefficient that determines the amount of power change until the process set power value, that is, it is a coefficient that determines the difference between the next set power and the current set power. The output suppression ratio is preferably set to a value greater than 0.8 and less than 0.95, and more preferably, it is expected to be set to 0.9. In the case where the output suppression ratio exceeds 0.95, there is a risk of overshoot depending on the monitoring value of Vpp. In addition, especially when the output suppression ratio is set to 1.0, it is possible that the monitoring value of Vpp exceeds the VppI / L setting value and the interlock function is activated. On the other hand, when the output suppression ratio is less than 0.8, the rising edge of the high-frequency power supplied to the RF antenna 81 becomes slower, which may cause deviations in the processing results of the plasma processing of the substrate W.

[0091] In the plasma processing according to the present embodiment, the high-power increase of the high-frequency power based on the above-mentioned formula (1) is repeated while feeding back the power of the high-frequency power according to the current Vpp value until the set power of the high-frequency power reaches the process set power value and inductively coupled plasma is generated in the plasma generation space P. At this time, since the process set power value is set to a value greater than the conversion power as described above, the capacitively coupled plasma in the plasma generation space P can be converted to inductively coupled plasma by making the set power reach the process set power value.

[0092] In addition, whether inductively coupled plasma is generated in the plasma generation space P can be determined based on, for example, the difference between the next set power and the current set power in the above formula (1). Specifically, when inductively coupled plasma is not generated in the plasma generation space P, since the current value of Vpp in the above formula (1) gradually increases, the difference between the next set power and the current set power gradually decreases. On the other hand, when inductively coupled plasma is generated in the plasma generation space P, since the resistance value of inductively coupled plasma is smaller than that of capacitively coupled plasma, as in Figure 1 As also shown in , the current value of Vpp in the above formula (1) decreases, and as a result, the next set power increases significantly relative to the current set power.

[0093] Therefore, in the plasma processing involved in the present embodiment, it can be set that, based on the difference between the next set power and the current set power caused by the change in the Vpp measurement value, it can be judged that the capacitively coupled plasma in the plasma generating space P is transformed into an inductively coupled plasma, and the subsequent plasma processing step can be entered at the moment when the risk of abnormal discharge is reduced.

[0094] When the inductively coupled plasma is generated in the plasma generating space P, the plasma processing of the substrate W is then performed according to the processing recipe acquired in step St2 ( Figure 4 Steps St3-5).

[0095] At this time, inductively coupled plasma is generated in step St3-4 in the plasma generating space P. As described above, the resistance value of inductively coupled plasma is smaller than that of capacitively coupled plasma, so even when high power (for example, 600 W or more) is supplied during plasma processing of the substrate W, the current flowing in the RF circuit is small and there is no problem, and the risk of abnormal discharge is reduced.

[0096] During the plasma treatment of the substrate W, the plasma generated in the plasma generation space P is supplied to the processing space S via the partition plate 61. Here, as described above, the partition plate 61 is formed with a maze structure, so that only the radicals generated in the plasma generation space P pass through the processing space S. Then, by causing the radicals supplied to the processing space S to act on the substrate W on the stage 90, the plasma treatment of the substrate W can be performed.

[0097] After that, when the desired processing result is obtained on the substrate W, the plasma processing in the plasma processing device 32 is terminated. When the plasma processing is terminated, the supply of high frequency power to the RF antenna 81 and the supply of the processing gas from the gas supply unit 70 are stopped. In addition, the exhaust unit 100 is operated to exhaust the processing gas remaining in the processing space S.

[0098] Next, the substrate W subjected to plasma treatment is transferred from the workbench 90 to the wafer transfer mechanism 40 and unloaded from the processing container 60. The substrate W unloaded from the processing container 60 is transferred to the load lock module 20 by the wafer transfer mechanism 40, and then passed through the cooling ( Figure 4 After step St4), the substrates W are stored in the front opening FOUP F placed on the load port 11. Then, when the desired plasma processing of all the substrates W stored in the front opening FOUP F is completed and the last substrate W is stored in the front opening FOUP F, a series of wafer processing in the vacuum processing system 1 is completed.

[0099] <Effects of the Technology Disclosed>

[0100] As described above, according to the plasma processing method involved in this embodiment, in order to continuously operate the plasma processing device 32 without generating abnormal discharge during plasma processing of the substrate W, control is performed so that the power is gradually increased to the process setting power value acquired in advance while the setting power of the high-frequency power is fed back according to the measured value of Vpp. In this way, the Vpp value is suppressed from rising to the specified value all at once during plasma processing, thereby suppressing the generation of abnormal discharge.

[0101] In addition, according to the present embodiment, the initial setting value of the high frequency power supplied to the RF antenna 81 during the plasma processing is set to a lower value of the parameter initial power value and the process setting power value. In the present embodiment, the parameter initial power value is set so that the Vpp value measured by supplying the parameter initial power value is smaller than the VppI / L setting value which is the threshold value for activating the interlock function, so that the generation of abnormal discharge can be further appropriately suppressed before the generation of plasma in the plasma generation space P (during the ignition delay time).

[0102] In addition, according to the present embodiment, the Vpp value is measured over time when the capacitively coupled plasma and the inductively coupled plasma are generated in the plasma generation space P, and the transition timing from the unignited state of plasma to the generated state of the capacitively coupled plasma and the transition timing from the capacitively coupled plasma to the plasma mode of the inductively coupled plasma in the plasma generation space P can be easily detected. Therefore, the switching timing of the control related to the plasma processing can be appropriately grasped, and the throughput rate related to the plasma processing can be appropriately shortened.

[0103] Furthermore, according to the present embodiment, the output suppression ratio in the above formula (1) is set to a value greater than or equal to 0.8 and less than or equal to 0.95. Thus, the set power can be made to reach the process set power value as quickly as possible while suppressing the generation of abnormal discharge when generating plasma to the plasma generating space P. In other words, the time until the inductively coupled plasma is generated to the plasma generating space P can be shortened while suppressing the generation of abnormal discharge.

[0104] Figure 7 to Figure 9 This is an example of the plasma processing according to the technology disclosed in the present invention, and shows that the initial power value of the high frequency power supplied to the RF antenna 81 is set to 100 W ( Figure 7 )、300W( Figure 8 )、500W( Fig. 9 ), and the process setting power value, initial power application time and output suppression ratio are set to 700W, 0.2msec, and 0.9 respectively. Figure 7 to Figure 9 In any of the cases shown, the initial power-on power is set by a parameter initial power value.

[0105] Moreover, as in Figure 7 to Figure 9 As shown in , according to the plasma processing involved in the technology of the present disclosure, as described above, no abnormal Vpp value occurs until the inductively coupled plasma (ICP) is generated in the plasma generating space P, that is, no abnormal discharge occurs and the interlock control operation is not performed.

[0106] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the appended claims and the gist thereof.

[0107] Description of Reference Numerals

[0108] 32: plasma processing device; 50: control device; 60: processing container; 81: RF antenna; 83: high-frequency power supply; 90: workbench; W: substrate.

Claims

1. A plasma processing method, which is a plasma processing method using a plasma processing device, comprising the following steps: acquiring parameters including a first initial power value, an initial power application time, and an output suppression ratio; acquiring a processing recipe including a process setting power value as a second initial power value; as well as determining the initial power applied to the plasma excitation antenna from one of the first initial power value and the second initial power value; When the first initial power value is determined as the initial power-on power, the plasma processing method includes the following steps: supplying the determined initial power-on to the plasma excitation antenna for a time period at least equal to the initial power application time; as well as The output of the high frequency power supplied to the plasma excitation antenna is gradually increased from the initial power supply to the process setting power value.

2. The plasma processing method according to claim 1, wherein: The initial power-on power is set to a lower power value between the first initial power value and the second initial power value.

3. The plasma processing method according to claim 2, wherein: The first initial power value is set to a value such that a peak-to-peak voltage value measured after the first initial power value is started to be supplied to the plasma excitation antenna and before the initial power application time elapses is less than a threshold value for activating an interlock function of the plasma processing apparatus.

4. The plasma processing method according to claim 1 or 2, wherein: When the second initial power value is determined as the initial power-on power, the plasma processing method includes the step of maintaining the output of the high frequency power supplied to the plasma excitation antenna at the process setting power value until inductively coupled plasma (ICP) is generated.

5. The plasma processing method according to any one of claims 1 to 3, wherein: The output of the high frequency power supplied to the plasma excitation antenna is gradually increased in each control cycle based on the following formula (1): Next output = current output × output suppression ratio × VppI / L setting value / Vpp current value…(1) Where, Next output: represents the output of the high frequency power supplied to the plasma excitation antenna in the next control cycle, Current output: represents the output of the high frequency power supplied to the plasma excitation antenna in the current control cycle, Output suppression ratio: A coefficient that determines the amount of output change until the process set power value is reached. VppI / L setting value: represents the threshold value for activating the interlock function of the plasma processing device, Vpp current value: represents the peak-to-peak voltage value measured when the current output is supplied to the plasma excitation antenna.

6. The plasma processing method according to claim 5, wherein: The output suppression ratio is set to a value of 0.8 or more and 0.95 or less.

7. A plasma processing device, comprising: Handling containers; A workbench, which is arranged inside the processing container and is used to place a substrate as a processing object; a plasma excitation antenna disposed above the processing container; a high-frequency power supply for supplying high-frequency power to the plasma excitation antenna; and a control unit, wherein: The control unit performs the following control: acquiring parameters including a first initial power value, an initial power application time, and an output suppression value; acquiring a processing recipe including a process setting power value as a second initial power value; as well as determining the initial power applied to the plasma excitation antenna from one of the first initial power value and the second initial power value; When the first initial power value is determined as the initial ON power, the control unit performs the following control: supplying the determined initial power-on to the plasma excitation antenna for a time period at least equal to or longer than the initial power application time; and The output of the high frequency power supplied to the plasma excitation antenna is gradually increased from the initial power supply to the process setting power value.

Images