Multiple voltage control method and multiple voltage control high frequency power supply device

Abstract

The multi-voltage control method of the present invention includes the following steps: (a) starting to supply high-frequency power to a plasma load; (b) executing a power surge action of continuing the output of the high-frequency power and increasing the output; (c) detecting a reflected wave reflected from the plasma load to the high-frequency power side, and determining whether a corresponding reflected wave loss amount corresponding to the amount of the reflected wave is greater than a first set value; (d) limiting the VDD magnitude of a DC voltage supplied to an RF power amplifier of the high-frequency power supply to a first limit when step (c) is satisfied; (e) after step (d), determining whether the corresponding reflected wave loss amount is less than a second set value, the second set value being less than the first set value; and (f) executing the power surge action of step (b) again when step (e) is satisfied.

Description

Technical Field

[0001] The present invention relates to a multi-voltage control method and a high-frequency power supply device with a multi-voltage control method for eliminating the unstable matching phenomenon, which minimizes the mismatching aspect after the ignition step or the matching action starts and solves the problem of stopping the process or damaging the main components due to reflected waves. Background Art

[0002] Plasma discharge is used to excite gas to generate active gas containing ions, free radicals, atoms and molecules. Active gas is widely used in various fields and is often used in large-screen display manufacturing processes or semiconductor manufacturing processes, for example, in processes such as etching, CVD (Chemical Vapor Deposition), ashing, etc.

[0003] Figure 1 is a block diagram illustrating a conventional plasma power supply system. Figure 1 The device for generating plasma generally consists of a plasma power supply 10 for supplying power, an impedance matching box 20 for supplying maximum power, and a plasma load 30. The plasma power supply 10 is composed of an RF oscillator (RF Generator) oscillating at a high frequency; the impedance matching box 20 matches the impedance of the output end of the plasma power supply 10 with the impedance of the plasma load 30 (for example, such as a processing chamber, where the impedance is not fixed but changes due to changes in the process type or the internal environment) to apply the required high-frequency power to the processing chamber.

[0004] Generally, the output impedance of the plasma power supply 10 is approximately fixed at 50 ohms, whereas the impedance of the plasma load 30 may vary in various ways. The impedance matching box 20 changes the impedance according to the impedance change of the load to match the impedance between the plasma power supply 10 and the processing chamber, thereby reducing the reflected wave from the plasma load 30, preventing the RF transmitter from being damaged, and fully using the high-frequency RF power in the processing chamber without loss.

[0005] The reflected wave reflected to the plasma power supply 10 side according to the impedance change of the plasma load 30 is inevitable, and in particular, a very high reflected wave is formed during plasma ignition. However, most high-frequency power supply devices perform a power surge operation to rapidly increase the output voltage for stable ignition, and ignore the reflected wave during the ignition operation.

[0006] The "Abnormal Discharge Suppression Device for Vacuum Equipment" of Korean Patent No. 10-1124789 has: a power control unit that controls a high-frequency power supply based on a deviation between a power command value and a power feedback value; and a power-off control unit that cuts off the power supply from the high-frequency power supply to the plasma reaction chamber based on the detection of abnormal discharge in the plasma reaction chamber. However, claim 9 of the prior art document describes a power-off control prohibition unit that prohibits arc detection until plasma ignition in the ignition mode section.

[0007] That is, the purpose of the above-mentioned prior art document is to forcibly maintain the power surge operation even if a reflected wave is detected (that is, an arc is detected) during the ignition operation, thereby performing a stable ignition operation. However, the following problem occurs.

[0008] The forced power surge operation as described above generates a reflected wave due to the matching instability phenomenon in the ignition step, and the reflected wave enters the power supply device side in reverse, which may damage the semiconductor switching element such as FET, which is an important element of the power amplifier.

[0009] To prevent this problem, the amount of transmitted power must be adjusted. However, the control method based on the deviation between the power command value and the feedback value is a structure that adjusts the power after the reflected wave occurs. Therefore, there is a problem that important components are damaged by the reflected wave before the transmission power is adjusted.

[0010] Furthermore, in the above-mentioned prior art, the ignition operation needs to be stopped in order to prevent damage to important components such as FET, but this has a problem of causing economic losses such as process interruption.

[0011] (Prior art literature)

[0012] (Patent Document)

[0013] Korean Patent No. 10-1124789 Summary of the invention

[0014] (Problem to be solved)

[0015] The object of the present invention is to provide a multi-voltage control method and a high-frequency power supply device with a multi-voltage control method, which can multiple-control the DC voltage provided to the power amplifier during the power surge action according to the amount of reflected waves reflected from the plasma load or the calculated value of the standing wave ratio (VSWR), thereby eliminating the impedance mismatching phenomenon after the ignition step or the start of the matching action, and can solve the problem of damage to major components or process interruption due to reflected waves.

[0016] (Methods of solving the problem)

[0017] A multi-voltage control method according to an embodiment of the present invention comprises the following steps: (a) starting to supply a high-frequency power supply to a plasma load; (b) executing a power surge action of continuously outputting the high-frequency power supply and increasing the output; (c) detecting a reflected wave reflected from the plasma load to the high-frequency power supply side, and determining whether a corresponding reflected wave loss amount corresponding to the amount of the reflected wave is greater than a first set value; (d) limiting the VDD magnitude of a DC voltage supplied to an RF power amplifier of the high-frequency power supply to a first limit when step (c) is satisfied; (e) after step (d), determining whether the corresponding reflected wave loss amount is less than a second set value, the second set value being less than the first set value; and (f) executing the power surge action of step (b) again when step (e) is satisfied.

[0018] A high-frequency power supply device with multiple voltage control methods according to an embodiment of the present invention is a high-frequency power supply device for supplying high-frequency power to a plasma load, comprising: a high-frequency power generating device for generating the high-frequency power; a detection module disposed at an output end of the high-frequency power generating device and detecting a traveling wave component directed toward the plasma load and a reflected wave component reflected from the plasma load; a comparison module for comparing the traveling wave component and the reflected wave component from the detection value of the detection module and extracting a corresponding reflected wave loss amount corresponding to the amount of the reflected wave component; a calculation module for comparing the corresponding reflected wave loss amount with a first set value and a second set value less than the first set value respectively to perform calculation; a multiple control module for switching control between a power surge mode and a first VDD limiting mode according to the output of the calculation module, wherein the power surge mode is for continuously increasing the output of the high-frequency power generating device and the first VDD limiting mode limits the magnitude of the DC voltage VDD supplied to the high-frequency power generating device to a first limit set in advance; and a DC module for controlling the magnitude of the DC voltage VDD input to an RF power amplifier according to the control of the multiple control modules.

[0019] (Effects of the Invention)

[0020] According to the multiple voltage control method and the high frequency power supply device of the multiple voltage control method of the present invention, the reflected wave reflected from the plasma load is detected, and the power impact mode and the VDD limiting mode are converted according to the corresponding reflected wave loss amount corresponding to the amount of the reflected wave to perform multiple controls. The VDD limiting mode controls the DC voltage supplied to the power amplifier, thereby eliminating the impedance mismatching phenomenon after the ignition step or the matching action starts, and can solve the problem of damage to the main components or process interruption due to the reflected wave. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1is a block diagram illustrating a conventional plasma power supply system;

[0022] Figure 2 is a block diagram illustrating a high frequency power supply device of the present invention;

[0023] Figure 3 is a block diagram showing a DC voltage control structure of a power amplifier according to the present invention;

[0024] Figure 4 is a flow chart illustrating a voltage control method of the present invention; and

[0025] Figure 5 is a graph illustrating the voltage control method of the present invention.

[0026] (Explanation of Reference Numerals)

[0027] 100: High frequency power generator 102: RF power amplifier

[0028] 110: Detection module 120: Comparison module

[0029] 130: calculation module 140: multiple control modules

[0030] 150: DC module 152: Rectifier

[0031] 154: DC-DC converter 156: DC-DC controller

[0032] 200: Matching device 300: Plasma load DETAILED DESCRIPTION

[0033] Additional objects, features and advantages of the present invention will become more clearly understood with reference to the following description and accompanying drawings.

[0034] Before describing the present invention in detail, the present invention may be subjected to various changes and may have various embodiments. The examples described below and shown in the accompanying drawings are not intended to limit the present invention to a specific embodiment, but should be understood to include all changes, equivalents and even substitutes included in the concept and technical scope of the present invention.

[0035] When describing that a certain component is "connected" or "contacting" another component, it may be directly connected or contacting the other component, but it should also be understood that there may be other components in between. On the contrary, when describing that a certain component is "directly connected" or "directly contacting" another component, it should be understood that there are no other components in between.

[0036] The terms used in this specification are only used to illustrate specific embodiments and are not intended to limit the present invention. For singular expressions, unless clearly defined in the text, plural expressions are included. In this specification, the terms "including" or "having" should be understood to specify only the existence of the features, numbers, steps, actions, components, parts or combinations thereof recorded in the specification, and do not exclude the existence or additional possibility of one or more other features, numbers, steps, actions, components, parts or combinations thereof in advance.

[0037] In addition, the terms "...part", "...unit", "...module" and the like described in the specification refer to a unit for processing at least one function or action, which can be implemented by hardware, software, or a combination of hardware and software.

[0038] In the description referring to the drawings, the same reference numerals are assigned to the same components regardless of the reference numerals, and repeated descriptions are omitted. In the description of the present invention, if it is determined that the description of the related known technology makes the present invention unclear, its detailed description will be omitted.

[0039] In addition, throughout the original specification, when a certain step is "above" or "before" another step, this not only refers to the case where a certain step and another step have a direct time series relationship, but also includes the case of an indirect time series in which the time series order can be reversed in the order of the two steps (such as a mixed step after each step), and both have the same scope of rights.

[0040] Figure 2 This is a block diagram illustrating a high-frequency power supply device according to the present invention.

[0041] Reference Figure 2 The high-frequency power supply device of the present invention includes: a high-frequency power generating device 100 for supplying high-frequency power to a plasma load 300, a detection module 110, a comparison module 120, a calculation module 130, a multi-control module 140, and a DC module 150.

[0042] like Figure 2 As shown, a matching device 200 may be provided between the high-frequency power generating device 100 and the plasma load 300, and the matching device 200 changes the impedance of the power supply side according to the impedance change of the load side to supply the high-frequency power. However, the device and method for eliminating the impedance mismatching aspect between the high-frequency power supply device and the plasma load 300 according to the present invention described below is not related to the matching device 200, but is achieved by controlling the output of the high-frequency power generating device 100 through the multi-control module 140.

[0043] The detection module 110 is a tool provided at the output end of the high frequency power generating device 100 and detecting the traveling wave component toward the plasma load 300 and the reflected wave component reflected from the plasma load. For example, the detection module 110 may be composed of a directional coupler and detect the components of the traveling wave and the reflected wave such as voltage, current, and frequency. Alternatively, the traveling wave power and the reflected wave power may be calculated from the detected components and output.

[0044] The comparison module 120 is a tool for extracting a corresponding reflected wave loss amount corresponding to the amount of the reflected wave component by comparing the traveling wave component and the reflected wave component from the detection value of the detection module 110. For example, the corresponding reflected wave loss amount is a standing wave ratio (VSWR: Voltage Standing Wave Ratio). Alternatively, the corresponding reflected wave loss amount may be a reflection loss calculated using the standing wave ratio. Here, the corresponding reflected wave loss amount may of course be replaced by any other value corresponding to the amount of the reflected wave.

[0045] The calculation module 130 is a tool for performing calculation by comparing the corresponding reflected wave loss with a first setting value and a second setting value that is smaller than the first setting value.

[0046] The first set value is set to prevent important components of the RF power amplifier from being damaged due to reflected waves during the ignition step, and can be set at the initial design stage of the high-frequency power generator 100 or the initial stage of the process of launching the high-frequency power generator 100. Preferably, the first set value is set to a value greater than 0.2 based on VSWR. In order to ensure a stable ignition operation, the first set value can be set relatively high; when the purpose of protecting the FET of the RF power amplifier is stronger than the ignition operation, it can be set lower.

[0047] The second set value is set as a value smaller than the first set value, and is set to stably continue the power surge operation in the ignition operation or the transition operation section of the high-frequency power generator 100. The second set value is set to a value at which the high-frequency power generator 100 and the plasma load 300 can maintain a stable matching state, which can be changed according to the type of process. Preferably, the second set value is set to a value smaller than 0.2 when the VSWR is used as a reference, and is set to a value less than half of the first set value.

[0048] The multi-control module 140 is a tool for switching control between a power striking mode and a first VDD limiting mode according to the output of the calculation module 130, wherein the power striking mode is to continue the output of the high-frequency power generating device 100 and increase the output, and the first VDD limiting mode is to limit the size of the DC voltage VDD provided to the high-frequency power generating device 100 to a first limit.

[0049] The DC module 150 is a tool for controlling the DC voltage, VDD, input to the RF power amplifier 102 of the high-frequency power generating device 100 according to the control of the multi-control module 140 .

[0050] Figure 3 is a block diagram showing a DC voltage control structure of a power amplifier according to the present invention.

[0051] Reference Figure 3 The high frequency power generating device 100 further includes: a rectifier 152 , a DC-DC converter 154 , an RF power amplifier 102 , and a DC-DC controller 156 .

[0052] The rectifier 152 rectifies the AC power stored by the power supplier. For example, the AC power is rectified into a DC positive voltage using a bridge diode. The rectified power is supplied to the components constituting the high-frequency power generating device. Although not shown, an EMI filter for eliminating electromagnetic noise may also be provided at the input end of the AC power.

[0053] The DC-DC converter 154 switches the output of the rectifier to supply a DC input voltage for controlling the operation of the RF power amplifier 102. The DC-DC controller 156 controls the VDD voltage of the input voltage of the RF power amplifier 102 by controlling the duty ratio of the switching elements constituting the DC-DC converter 154.

[0054] The RF power amplifier 102 amplifies the output of the DC-DC converter 154 to generate high frequency power. The generated high frequency power is transmitted to the plasma load 300. The RF power amplifier 102 is a device that can operate two or more RF power amplifiers in parallel to generate voltage and frequency according to various load conditions.

[0055] According to the present invention, the multi-control module 140 performs the following control: based on the calculation result received from the calculation module 130, the high-frequency power generating device 100 is operated in the power impact mode (a mode of continuing the output of the high-frequency power supply and increasing the output for plasma ignition) at the time when the power supply starts, and in the case where the corresponding reflected wave loss is greater than the first set value, the first VDD limiting mode is operated, and in the case where the corresponding reflected wave loss is reduced to less than the second set value during the operation in the first VDD limiting mode, the operation is returned to the power impact mode. This control is that the multi-control module 140 issues a voltage instruction to the DC-DC controller 156, and the DC-DC controller 156 controls the voltage of the DC-DC converter 154. For the specific control process, please refer to Figure 4 and 5 This is described in detail below.

[0056] Figure 4 is a flow chart illustrating a voltage control method of the present invention; Figure 5 is a graph illustrating the voltage control method of the present invention.

[0057] Reference Figure 4 The high-frequency power generator 100 of the present invention starts to supply high-frequency power to the plasma load 300 (ST110). Then, in order to ignite the plasma, a power surge operation is performed to continue the output of the high-frequency power and increase the output (ST120). Figure 5 In the description referring to the interval t1, the output of the high frequency power generating device 100 increases linearly.

[0058] When the high frequency power generating device 100 starts to operate, the detection module 110 continuously detects the traveling wave component and the reflected wave component. Based on the calculation results of the comparison module 120 and the calculation module 130, the multi-control module 140 determines whether to continue the power surge mode.

[0059] In the next step, it is determined whether the corresponding reflected wave loss is greater than the first set value (ST130). If the corresponding reflected wave loss is greater than the first set value, the multi-control module 140 limits the magnitude of the DC voltage VDD supplied to the RF power amplifier 102 to the first limit (ST140). Figure 5 In the description of the interval from t1 to t2 in FIG. 1 , according to the first VDD limiting mode operation in which the magnitude of VDD is limited to the first limit, the output of the high frequency power generating device 100 remains unchanged and does not increase.

[0060] If the corresponding reflected wave loss amount is less than the first set value until the ignition action is completed, the power surge action can be continued.

[0061] After step ST140, it is determined whether the corresponding reflected wave loss is less than a second set value, and the second set value is less than the first set value (ST150). If step ST150 is not satisfied, the first VDD limit mode operation of ST140 can be maintained.

[0062] If the condition of step ST150 is met, the power surge action is performed again to continuously increase the output of the high-frequency power generating device 100 until ignition (ST160). Figure 5 As described in the interval from t2 to t3, the output continues to increase.

[0063] After executing step ST160, a second VDD limit mode operation (ST170) is executed to limit the size of VDD to a second limit, wherein the second limit is greater than the first limit. The second limit is set to a value where the power supplied from the high-frequency power generating device 100 to the plasma load 300 is less than a set power (Set Power) defined in advance. Figure 5 In the case where the set power is reached, as shown in the curve after t3, the operation is performed in the second VDD limit mode in order to constantly limit the output of the high-frequency power generator 100. For example, after the ignition operation is completed, the output of the high-frequency power generator 100 is limited to a predetermined level to achieve process stability and prevent excessive output increase and arcing caused thereby.

[0064] The above-mentioned embodiments are described by limited drawings, but as long as a person with ordinary knowledge in the technical field can apply various technical modifications and variations based on them. For example, the above-mentioned techniques are performed in a different order from the described method, and / or the components of the described system, structure, device, circuit, etc. are combined or combined in a different form from the above method, or even replaced or replaced by other components or equivalents, appropriate effects can be achieved.

[0065] The embodiments and drawings described in this specification are only examples of a part of the technical ideas included in the present invention. Accordingly, the embodiments disclosed in this specification are not used to limit the technical ideas of the present invention, but are used for illustration, and the scope of the technical ideas of the present invention shall not be limited by such embodiments, and this is obvious. All modified examples and specific embodiments that can be easily inferred by those skilled in the art within the scope of the technical ideas included in the description and drawings of the present invention should be interpreted as all included in the scope of the rights of the present invention.

Claims

1. A multi-voltage control method, comprising the following steps: (a) Start supplying high frequency power to the plasma load; (b) performing a power surge operation of continuously outputting a high-frequency power supply and increasing the output; (c) detecting a reflected wave reflected from the plasma load to the high-frequency power supply side, and determining whether a corresponding reflected wave loss amount corresponding to the amount of the reflected wave is greater than a first set value; (d) when the condition of step (c) is satisfied, limiting the magnitude of the DC voltage VDD supplied to the RF power amplifier of the high frequency power supply to a first limit; (e) after step (d), determining whether the corresponding reflected wave loss is less than a second set value, the second set value being less than the first set value; and (f) If step (e) is satisfied, the power surge action of step (b) is performed again. After step (f), the method further comprises the following steps: (g) limiting the magnitude of the VDD to a second limit, the second limit being greater than the first limit.

2. The multi-voltage control method according to claim 1, characterized in that: The electric power supplied from the high frequency power source to the plasma load is smaller than a set electric power defined in advance by the second limit.

3. The multi-voltage control method according to claim 1 or 2, characterized in that: The corresponding reflected wave loss amount is calculated by a ratio of a traveling wave from the high frequency power source toward the plasma load to a reflected wave reflected from the plasma load toward the high frequency power source.

4. The multi-voltage control method according to claim 1 or 2, characterized in that: The first setting value is a value greater than the second setting value by at least two times.

5. The multi-voltage control method according to claim 4, characterized in that: The first setting value has a value greater than or equal to 0.2, and the second setting value has a value less than 0.

2.

6. A high-frequency power supply device with multiple voltage control modes, which supplies high-frequency power to a plasma load, comprising: A high-frequency power generating device, generating the high-frequency power supply; a detection module, which is disposed at the output end of the high frequency power generating device and detects a traveling wave component toward the plasma load and a reflected wave component reflected from the plasma load; a comparison module, which compares the traveling wave component and the reflected wave component from the detection value of the detection module, and extracts a corresponding reflected wave loss amount corresponding to the amount of the reflected wave component; A calculation module, which compares the corresponding reflected wave loss with a first set value set in advance and a second set value which is smaller than the first set value to perform calculation; a multiple control module, causing the high-frequency power generating device to operate in a power surge mode at a time point when power supply starts, wherein the power surge mode is a mode for continuously increasing the output of the high-frequency power generating device; when the corresponding reflected wave loss amount is greater than the first set value, the multiple control module causes the high-frequency power generating device to operate in a first VDD limiting mode, wherein the first VDD limiting mode limits the size of VDD, which is a DC voltage supplied to the high-frequency power generating device, to a first limit set in advance; when the corresponding reflected wave loss amount is reduced to less than the second set value during the operation in the first VDD limiting mode, the multiple control module causes the high-frequency power generating device to return to the power surge mode to operate; after the power surge mode, the multiple control module causes the high-frequency power generating device to operate in a second VDD limiting mode that limits the size of VDD to a second limit, wherein the second limit is greater than the first limit; The DC module controls the magnitude of the DC voltage VDD input to the RF power amplifier according to the control of the multiple control modules.

7. The high frequency power supply device of the multi-voltage control method according to claim 6, characterized in that: The power supplied from the high-frequency power generator to the plasma load is smaller than a set power defined in advance by the second limit.

8. The high frequency power supply device of multiple voltage control method according to claim 6 or 7, characterized in that: The corresponding reflected wave loss is calculated by the ratio of the traveling wave component to the reflected wave component.

9. The high frequency power supply device of the multi-voltage control method according to claim 6 or 7, characterized in that: The first setting value is greater than the second setting value by more than 2 times.

10. The high frequency power supply device of multiple voltage control method according to claim 9, characterized in that: The first set value has a value greater than or equal to 0.2, and the second set value has a value less than 0.2.

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