Plasma processing device

Abstract

The present invention eliminates abnormal discharge without interrupting plasma generation. A plasma processing device (101) comprises: a vacuum container (1), the inside of which is vacuum evacuated; an antenna (3) that generates plasma inside the vacuum container (1); a high-frequency power supply (4) that supplies high-frequency power to the antenna (3); a bias power supply (5) that applies a bias voltage to a workpiece (10); a detection unit (6) that detects the output current and the output voltage of the bias power supply (5); an arc determination unit (71) that, on the basis of the detected output current and output voltage, determines the occurrence of an abnormal discharge (arc) inside the vacuum container (1); and a power control unit (73) that, when the occurrence of an abnormal discharge is determined, stops the output of the bias power supply (5), and reduces the output of the high-frequency power supply (4) so as to limit the high-frequency power to a power level between the minimum power needed for the plasma to not disappear and the maximum power needed to eliminate the abnormal discharge.

Description

Plasma processing equipment

[0001] The present disclosure relates to a plasma processing apparatus.

[0002] Conventionally, plasma processing apparatuses such as sputtering apparatuses have been provided with a function for extinguishing abnormal discharges, because abnormal discharges, mainly arc discharges, occurring within a vacuum chamber can damage the workpiece. For example, Patent Document 1 discloses a plasma processing apparatus that, when abnormal discharges are detected within a chamber, temporarily reduces the outputs of a target bias power supply and a high-frequency power supply, thereby halting the generation of plasma and the ejection of sputtered particles and thereby extinguishing the abnormal discharge.

[0003] Japanese Patent Application Publication No. 2020-200511

[0004] In the plasma processing apparatus disclosed in Patent Document 1, when an abnormal discharge is detected, the output of the high-frequency power supply is reduced to stop the generation of plasma. Therefore, after the abnormal discharge has disappeared, the output of the high-frequency power supply must be increased to generate plasma. Therefore, this plasma processing apparatus has the problem of reduced productivity.

[0005] An object of one aspect of the present disclosure is to extinguish abnormal discharge without interrupting plasma generation.

[0006] In order to solve the above problems, a plasma processing apparatus according to one embodiment of the present disclosure includes a vacuum vessel whose interior is evacuated to a vacuum, a plasma generating unit that generates plasma inside the vacuum vessel, a high-frequency power supply that supplies high-frequency power to the plasma generating unit, a bias power supply that applies a bias voltage to a target or workpiece, a detection unit that detects the output current and output voltage of the bias power supply, a determination unit that determines the occurrence of abnormal discharge inside the vacuum vessel based on the detected output current and output voltage, and a control unit that, when the occurrence of abnormal discharge is determined, stops the output of the bias power supply and reduces the output of the high-frequency power supply so as to limit the high-frequency power to a power between the minimum power at which the plasma is not extinguished and the maximum power at which the abnormal discharge is extinguished.

[0007] According to one aspect of the present disclosure, abnormal discharge can be extinguished without interrupting plasma generation.

[0008] 1 is a diagram showing a configuration of a plasma processing apparatus according to a first embodiment of the present disclosure, a waveform diagram showing control of power of a high frequency power supply and a bias power supply when an arc is generated in the plasma processing apparatus, and a diagram showing a configuration of a plasma processing apparatus according to a second embodiment of the present disclosure.

[0009] First Embodiment A first embodiment of the present disclosure will be described in detail below.

[0010] <Configuration of Plasma Processing Apparatus> FIG. 1 is a diagram showing the configuration of a plasma processing apparatus 101 according to the first embodiment.

[0011] 1, a plasma processing apparatus 101 is an apparatus that performs processes such as carburizing, nitriding, ashing, etching, and deposition on a workpiece 10 (object to be processed) using an inductively coupled plasma P. The plasma processing apparatus 101 includes a vacuum chamber 1, a vacuum exhaust device 2, an antenna 3 (plasma generating unit), a high-frequency power supply 4, a bias power supply 5, a detection unit 6, an arc control unit 7, and a high-frequency window 11.

[0012] A vacuum vessel 1 is a vessel into which a gas G (e.g., a reactive gas) is introduced. The interior of the vacuum vessel 1 is evacuated by a vacuum exhaust device 2. The vacuum vessel 1 is made of, for example, metal and is electrically grounded.

[0013] An opening 1a penetrating the upper wall in the thickness direction of the upper wall is formed in the upper wall of the vacuum vessel 1. The opening 1a is closed by a radio frequency window 11. The radio frequency window 11 has a support member 11a and a dielectric plate 11b.

[0014] The support member 11a is an annular member having a constant thickness and an opening formed therein that has approximately the same size and shape as the opening 1a. The support member 11a is fixed to the periphery of the opening 1a.

[0015] The dielectric plate 11b is fixed onto the support member 11a so as to cover the opening 1a and the opening of the support member 11a. The dielectric plate 11b is a plate-shaped member made entirely of a dielectric material, such as ceramics, inorganic material, or resin material. The gap between the vacuum vessel 1 and the support member 11a, and the gap between the support member 11a and the dielectric plate 11b are sealed with sealing members.

[0016] An exhaust pipe 1b is provided on the bottom wall of the vacuum vessel 1. The exhaust pipe 1b is a pipe that connects the inside of the vacuum vessel 1 with the vacuum exhaust device 2. A gate valve (not shown) is arranged between the vacuum exhaust device 2 and the exhaust pipe 1b. The gate valve has an adjustable opening. By adjusting the opening of the gate valve, the amount of exhaust by the vacuum exhaust device 2 is adjusted. By adjusting the amount of exhaust, the degree of vacuum inside the vacuum vessel 1 is adjusted.

[0017] A power supply terminal 1d is provided on the bottom wall of the vacuum vessel 1. The power supply terminal 1d is electrically connected to the bias power supply 5 and also to a workpiece holder (not shown) that holds the workpiece 10 placed inside the vacuum vessel 1.

[0018] A gas inlet 1c is provided on the side wall of the vacuum vessel 1 to introduce a gas G into the vacuum vessel 1. The gas G (reactive gas) is oxygen (O ２ ) or nitrogen (N ２ ) is used.

[0019] The antenna 3 generates an induced electric field when a high-frequency current flows due to the supply of high-frequency power from the high-frequency power source 4. This causes the antenna 3 to generate plasma inside the vacuum vessel 1. The antenna 3 has a linear main body and curved ends provided on both sides of the main body. The antenna 3 is disposed outside the vacuum vessel 1 in a position close to the high-frequency window 11, with the main body facing the opening 1a. One end of the antenna 3, which serves as the power supply end, is connected to the high-frequency power source 4, and the other end, which serves as the termination end of the antenna 3, is grounded. The antenna 3 is formed from a material such as copper, aluminum, an alloy thereof, or stainless steel, but may be formed from other materials.

[0020] The number of antennas 3 is not limited to one, and may be multiple. When multiple antennas 3 are provided, they are arranged in parallel with each other at intervals.

[0021] The high frequency power supply 4 is a power supply that supplies high frequency power to the antenna 3. The frequency of the high frequency power is, for example, a general 13.56 MHz, but is not limited to this.

[0022] The bias power supply 5 is a power supply that applies a bias voltage to the workpiece 10. The bias power supply 5 applies the bias voltage to the workpiece 10 held by the workpiece holding portion via the workpiece holding portion. The bias voltage is a DC voltage, but may also be a pulse voltage.

[0023] The detection unit 6 detects the output current and output voltage of the bias power supply 5. Specifically, the detection unit 6 has an ammeter 61 that detects the output current of the bias power supply 5 and a voltmeter 62 that detects the output voltage of the bias power supply 5.

[0024] When an arc, which is an abnormal discharge, occurs inside the vacuum vessel 1, the arc control unit 7 stops the output of the bias power supply 5 and limits the high frequency power of the high frequency power supply 4. In order to realize such a power supply control function, the arc control unit 7 has an arc determination unit 71 (determination unit), a timer 72, and a power control unit 73 (control unit). Note that the timer 72 may be omitted as described below, and is therefore not an essential component.

[0025] The arc determination unit 71 determines whether an arc has occurred inside the vacuum vessel 1 based on the output current of the bias power supply 5 detected by the ammeter 61 and the output voltage of the bias power supply 5 detected by the voltmeter 62. The arc determination unit 71 also determines whether an arc has extinguished inside the vacuum vessel 1 based on the output current of the bias power supply 5 detected by the ammeter 61.

[0026] Specifically, the arc determination unit 71 determines that an arc has occurred when the detection value of the ammeter 61 is equal to or greater than the current threshold, and determines that an arc has extinguished when the detection value of the ammeter 61 is 0. The arc determination unit 71 also determines that an arc has occurred when the detection value of the voltmeter 62 is equal to or less than the voltage threshold.

[0027] Timer 72 measures time until a predetermined time has elapsed since arc determination unit 71 determined that an arc has occurred.

[0028] When the arc determination unit 71 determines that an arc has occurred, the power control unit 73 stops the output of the bias power supply 5. Furthermore, when the arc determination unit 71 determines that an arc has occurred, the power control unit 73 reduces the output of the high frequency power supply 4 so as to limit the high frequency power of the high frequency power supply 4 to a power between the minimum power at which the plasma is not extinguished and the maximum power at which the arc is extinguished. The minimum power at which the plasma is not extinguished is lower than the maximum power at which the arc is extinguished.

[0029] The minimum power at which plasma does not disappear is a power greater than the power at which the generated plasma begins to disappear (disappearance power) and is calculated by adding a predetermined margin to the dissipation power. The maximum power at which the arc disappears is the maximum power at which the arc completely disappears. The minimum power at which plasma does not disappear and the maximum power at which the arc disappears are each set in advance based on data obtained through experiments, etc.

[0030] When the arc determination unit 71 determines that the arc has been extinguished, the power control unit 73 restores the output of the high frequency power supply 4 and the output of the bias power supply 5 .

[0031] The power control unit 73 may restore the output of the high frequency power supply 4 and the output of the bias power supply 5 a predetermined time after it is determined that an arc has occurred, i.e., when the timer 72 has completed counting the predetermined time. The predetermined time is the time from when it is determined that an arc has occurred, i.e., when the restriction on the high frequency power of the high frequency power supply 4 begins as described above, to when the arc is extinguished, and is set based on a time obtained by experiment or the like. Note that the timer 72 is omitted when the extinguishment of the arc is determined by the arc determination unit 71 as described above.

[0032] <Power Control During Arc Generation> FIG. 2 is a waveform diagram showing the control of the power of the high frequency power supply 4 and the bias power supply 5 during arc generation in the plasma processing apparatus 101. As shown in FIG.

[0033] As shown in FIG. 2, when the plasma processing apparatus 101 performs normal processing on the workpiece 10, the bias power supply 5 operates to output a specified current and voltage, and the high frequency power supply 4 outputs a specified high frequency power to generate plasma.

[0034] In contrast, when an arc occurs, the output current of the bias power supply 5 increases and the output voltage of the bias power supply 5 decreases. The arc determination unit 71 determines that an arc has occurred when at least one of the following conditions is met: the output current detected by the detection unit 6 is equal to or greater than the current threshold value, or the output voltage detected by the detection unit 6 is equal to or less than the voltage threshold value.

[0035] When the arc determination unit 71 determines that an arc has occurred, the power control unit 73 stops the output of the bias power supply 5. This reduces the output current of the bias power supply 5 and also reduces the output voltage of the bias power supply 5. However, this alone is not enough to extinguish the arc.

[0036] Therefore, when the arc determination unit 71 determines that an arc has occurred, the power control unit 73 reduces the output of the high frequency power supply 4. At this time, the power control unit 73 does not stop the high frequency output of the high frequency power supply 4, but rather limits the high frequency output to a range equal to or greater than the minimum power at which the plasma is not extinguished and equal to or less than the maximum power at which the arc is extinguished, as described above. As a result, the arc is extinguished while the generation of plasma is maintained.

[0037] After the output of bias power supply 5 and the output of high frequency power supply 4 decrease, the output voltage of bias power supply 5 decreases instantaneously to 0 V, but the output current of bias power supply 5 is affected by the arc and decreases more gradually than the output voltage to reach 0 A. Therefore, arc determination unit 71 determines that the arc has extinguished based on the fact that the output current is no longer affected by the arc and has reached 0 A.

[0038] When arc determination unit 71 determines that the arc has been extinguished, power control unit 73 restores the outputs of high frequency power supply 4 and bias power supply 5. This causes plasma processing apparatus 101 to return to an operating state in which normal processing is performed.

[0039] When the timer 72 has counted a predetermined time since the arc determination unit 71 determined that an arc has occurred, it can be assumed that the arc has been extinguished. For this reason, the power control unit 73 may restore the outputs of the high frequency power supply 4 and the bias power supply 5 when the timer 72 has counted the predetermined time, instead of having the arc determination unit 71 determine that the arc has extinguished. This omits the arc determination unit 71 from determining that the arc has extinguished, thereby reducing the processing load on the arc control unit 7.

[0040] In this way, when an arc occurs, the plasma processing apparatus 101 stops the output of the bias power supply 5 and reduces the output of the high-frequency power supply 4 so that the power is limited to a range where the arc is extinguished but the plasma is not extinguished. This allows the arc to be extinguished while maintaining plasma generation. Therefore, unlike prior art in which plasma generation is interrupted when an arc occurs, it is not necessary to regenerate plasma after the arc is extinguished. This therefore shortens the time it takes for the plasma P to return to the state required for processing the workpiece 10. This reduces the decrease in productivity when an arc occurs.

[0041] Furthermore, when the arc is extinguished, plasma processing apparatus 101 restores the outputs of high frequency power supply 4 and bias power supply 5. This allows plasma processing apparatus 101 to quickly return to an operating state for performing normal processing.

[0042] [Embodiment 2] Embodiment 2 of the present disclosure will be described below. For ease of explanation, components having the same functions as those described in the above embodiment 1 will be denoted by the same reference numerals, and the description thereof will not be repeated.

[0043] FIG. 3 is a diagram showing the configuration of a plasma processing apparatus 102 according to the second embodiment.

[0044] 3, plasma processing apparatus 102 is an apparatus that performs sputtering processing on substrate 20 using inductively coupled plasma P. Plasma processing apparatus 102 includes vacuum chamber 1, vacuum exhaust device 2, antenna 3, high frequency power supply 4, bias power supply 5, detection unit 6, and arc control unit 7.

[0045] The vacuum vessel 1 in the second embodiment does not have an opening 1a, unlike the vacuum vessel 1 in the first embodiment. In addition, an inert gas such as argon (Ar) is introduced into the vacuum vessel 1 in the second embodiment as a sputtering gas G through a gas inlet 1c.

[0046] The antenna 3 is disposed so that the main body is located inside the vacuum vessel 1. The main body of the antenna 3 is covered with an insulating tube 8 formed into a straight tube shape from an insulating material. When a high-frequency current flows through the antenna 3, a plasma P is generated around the antenna 3 inside the vacuum vessel 1.

[0047] There is no seal between the vacuum vessel 1 and both ends of the antenna 3 in the insulating tube 8. Even if gas G enters the space inside the insulating tube 8, the space is small and the electrons travel a short distance, so plasma P is not normally generated in the space.

[0048] The antenna 3 penetrates two opposing side walls of the vacuum vessel 1 at both ends of the main body. A tubular insulating member 9 is provided on each side wall, and the antenna 3 penetrates the interior of the insulating member 9. The gap between the insulating member 9 and the antenna 3 is sealed, for example, by packing. The gap between the insulating member 9 and the vacuum vessel 1 is also sealed, for example, by packing.

[0049] A substrate 20, which is the target of film formation, is held by a substrate holder (not shown) and disposed on the upper wall inside the vacuum chamber 1. A target 30 is held by a target holder (not shown) and disposed on the bottom wall inside the vacuum chamber 1. The output voltage of a bias power supply 5 is applied to the target 30 via a power supply terminal 1d and the target holder.

[0050] The target 30 is a film forming material to be formed on the substrate 20. The target 30 has a material that corresponds to the film to be formed on the substrate 20. The shape of the target 30 is, for example, a flat plate, and its planar shape is, for example, rectangular, but is not limited to this and may be circular or the like.

[0051] The bias power supply 5 in the second embodiment applies a target bias voltage as an output voltage to the target 30. The target bias voltage is a voltage that attracts ions in the plasma P to the target 30 and causes sputtering.

[0052] In the plasma processing apparatus 102 configured as described above, similarly to the above-described plasma processing apparatus 101, when the arc determination unit 71 determines that an arc has occurred inside the vacuum vessel 1, the output of the bias power supply 5 is stopped and the output of the high frequency power supply 4 is reduced. Also in the plasma processing apparatus 102, similarly to the plasma processing apparatus 101, when the arc is extinguished, the outputs of the high frequency power supply 4 and the bias power supply 5 are restored.

[0053] This allows the arc to be extinguished while maintaining plasma generation. Therefore, unlike prior art in which plasma generation is interrupted when an arc is generated, it is not necessary to regenerate plasma after the arc is extinguished. This reduces the time it takes for plasma P to return to the state required for sputtering the substrate 20. This reduces the decrease in productivity when an arc is generated.

[0054] In addition, in the plasma processing apparatus 102 serving as a sputtering apparatus, the high-frequency power of the high-frequency power supply 4 was confirmed as follows based on actual measurement data. The above-mentioned dissipation power was 0.09 kW / m, and the maximum power at which the arc was extinguished was 0.73 kW / m. The minimum power at which the plasma was not extinguished was approximately 0.1 kW / m, which is the dissipation power plus a margin. When such an antenna 3 was used, the high-frequency power used for sputtering was 1.84 kW / m. The plasma processing apparatus 102 from which the above-mentioned measurement data was obtained had four antennas 3, each with a length of 1.355 m. In addition, in the plasma processing apparatus 102, the dissipation power and the maximum power at which the arc was not extinguished were expressed as the high-frequency power supplied from the high-frequency power supply 4 divided by the total length of the antennas 3.

[0055] It should be noted that the above values ​​for the minimum power at which the plasma is not extinguished and the maximum power at which the arc is extinguished are merely examples, and the present invention is not limited to these values.

[0056] [Example of Software Implementation] The functions of the arc control unit 7 can be implemented by a program for causing a computer to function as the arc control unit 7. The program is a program for causing a computer to function as each control block of the arc control unit 7.

[0057] In this case, the arc control unit 7 includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The functions described in each of the above embodiments are realized by executing the program using the control device and storage device.

[0058] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0059] In addition, some or all of the functions of the control blocks can be realized by logic circuits. For example, the scope of the present disclosure also includes an integrated circuit in which a logic circuit that functions as each of the control blocks is formed.

[0060] [Summary] A plasma processing apparatus according to a first aspect of the present disclosure includes a vacuum vessel whose interior is evacuated to a vacuum, a plasma generating unit that generates plasma inside the vacuum vessel, a high-frequency power supply that supplies high-frequency power to the plasma generating unit, a bias power supply that applies a bias voltage to a target or workpiece, a detection unit that detects the output current and output voltage of the bias power supply, a determination unit that determines the occurrence of abnormal discharge inside the vacuum vessel based on the detected output current and output voltage, and a control unit that, when the occurrence of abnormal discharge is determined, stops the output of the bias power supply and reduces the output of the high-frequency power supply so as to limit the high-frequency power to a power between the minimum power at which the plasma is not extinguished and the maximum power at which the abnormal discharge is extinguished.

[0061] In the above configuration, when it is determined that an abnormal discharge has occurred inside the vacuum chamber, the output of the bias power supply is stopped, and the output power of the reduced high-frequency power supply is limited to a power between the minimum power at which plasma is not extinguished and the maximum power at which the abnormal discharge is extinguished. This causes the abnormal discharge to extinguish while maintaining plasma generation. In this way, even if an abnormal discharge occurs, plasma generation is maintained. Therefore, there is no need to generate plasma again after the abnormal discharge has extinguished, and it is possible to reduce the decrease in productivity when an abnormal discharge occurs.

[0062] In the plasma processing apparatus according to the second aspect of the present disclosure, in the first aspect, the judgment unit may judge the extinction of abnormal discharge inside the vacuum vessel based on the detected output current, and the control unit may restore the output of the bias power supply and the output of the high-frequency power supply when it is determined that the abnormal discharge has extinct.

[0063] Even if the output of the bias power supply is stopped due to the arc detection, the output current of the bias power supply does not become zero due to the influence of the arc. Therefore, in the above configuration, it is determined that the abnormal discharge has ceased based on the output current of the bias power supply (specifically, that it is zero). When it is determined that the abnormal discharge has ceased, the outputs of the bias power supply and the high-frequency power supply are restored. This makes it possible to determine the cessation of the abnormal discharge depending on the state of the abnormal discharge that has occurred. Therefore, the plasma processing apparatus can be quickly returned to an operating state for performing normal processing.

[0064] In the plasma processing apparatus according to the third aspect of the present disclosure, in the first aspect, the control unit may restore the output of the bias power supply and the output of the high-frequency power supply a predetermined time after it is determined that the abnormal discharge has occurred.

[0065] In the above configuration, the bias power supply output and the high-frequency power supply output are restored a predetermined time after the occurrence of abnormal discharge is determined. As a result, if the predetermined time is set based on the time it takes for the abnormal discharge to disappear, which is estimated by experiment or the like, the power can be restored after the abnormal discharge has disappeared.

[0066] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Furthermore, embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

[0067] REFERENCE SIGNS LIST 1 vacuum vessel 3 antenna (plasma generating section) 4 high frequency power supply 5 bias power supply 6 detection section 10 work (object to be processed) 30 target 71 arc determination section (determination section) 72 timer 73 power control section (control section) 101, 102 plasma processing apparatus

Claims

1. A plasma processing apparatus comprising: a vacuum vessel whose interior is evacuated to a vacuum; a plasma generating unit that generates plasma inside the vacuum vessel; a high-frequency power supply that supplies high-frequency power to the plasma generating unit; a bias power supply that applies a bias voltage to a target or workpiece; a detection unit that detects the output current and output voltage of the bias power supply; a determination unit that determines the occurrence of abnormal discharge inside the vacuum vessel based on the detected output current and output voltage; and a control unit that, when the occurrence of abnormal discharge is determined, stops the output of the bias power supply and reduces the output of the high-frequency power supply so as to limit the high-frequency power to a power between the minimum power at which the plasma is not extinguished and the maximum power at which the abnormal discharge is extinguished.

2. The plasma processing apparatus of claim 1, wherein the judgment unit judges whether the abnormal discharge inside the vacuum vessel has ceased based on the detected output current, and the control unit restores the output of the bias power supply and the output of the high-frequency power supply when it is determined that the abnormal discharge has ceased.

3. The plasma processing apparatus according to claim 1, wherein the control unit restores the output of the bias power supply and the output of the high frequency power supply a predetermined time after it is determined that the abnormal discharge has occurred.

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