Matching-free plasma source and working method thereof

Abstract

The invention discloses a Matchless plasma source and a working method of the Matchless plasma source. The unmatched plasma source according to an embodiment may include: a detector connected to a reaction circuit for detecting a radio frequency (RF) voltage or current at the reaction circuit end; the reaction circuit is arranged at the output end of the unmatched plasma source; and a controller connected to the reaction circuit and the detector, and calculating and controlling a tuning frequency and a pulse width of the radio frequency power supplied by the unmatched plasma source, and a direct current (DC) voltage, based on a reactance of the reaction circuit and the radio frequency voltage or current detected by the detector.

Description

Technical Field

[0001] The invention discloses a plasma source used in a plasma processing device and a working method thereof. Background Art

[0002] Plasma processing equipment is used as a core device in the semiconductor processing steps of etching, vapor deposition, and cleaning pure semiconductor wafers.

[0003] Typically, a plasma processing apparatus includes a plasma chamber, a high-frequency power generator (RFGenerator) for generating high-frequency power, and an impedance matcher (Impedance Matcher) for matching the output impedance of the RFGenerator with the impedance of the plasma chamber to minimize power loss in the plasma chamber and supply maximum power.

[0004] Conventionally, plasma processing apparatuses typically employ a structure in which a high-frequency power generator, an impedance matcher, and a plasma chamber are physically separated and connected via coaxial cables, etc. However, such a structure can cause problems such as instability and transmission loss due to mismatching.

[0005] To address the aforementioned issues, an integrated structure has been proposed that integrates a high-frequency power generator, an impedance matching box, and a plasma chamber. This integrated structure has been disclosed in Korean Patent Publication Nos. KR10-2020-0059310, KR10-2020-0121909, and KR10-2021-0034059.

[0006] The integrated structure achieves a matching effect by adjusting the impedance of the reaction circuit and the radio frequency (RF) frequency of the signal generator to offset the jX component, which is the imaginary part, from the R+jX equivalent circuit impedance of the plasma chamber, leaving only the R component, which is the real part, to form a minimum impedance state. The structure then transmits maximum power to the plasma chamber by making the phases of the voltage and current in phase (In Phase).

[0007] In this case, the magnitude of the RF power can be adjusted by the voltage of the arbitrary waveform generator, and the integrated structure is provided by generating an arbitrary output waveform through the arbitrary waveform generator.

[0008] That is, the integrated structure can replace the function of the existing impedance matching box by using the reaction circuit and voltage adjustment method, thereby achieving simplification and miniaturization of the device.

[0009] However, since the integrated structure uses an arbitrary waveform generator that is independent of the RF signal generator used to generate RF power to quickly change the voltage of the DC power supply to the amplitude of the high-frequency power, it has the disadvantages of slow response speed, low power efficiency, high price, and inability to maximize miniaturization.

[0010] Therefore, it is necessary to propose a technology for solving the disadvantages of the integrated structure. Summary of the Invention

[0011] Technical issues

[0012] To improve response speed and power efficiency, reduce price, and maximize miniaturization, one embodiment provides a non-matched plasma source that controls an RF signal generator by generating RF power with controlled tuning frequency and pulse width from the RF signal generator without an arbitrary waveform generator.

[0013] However, the purpose of the present invention is not limited to the above-mentioned purpose, and various extensions can be made without departing from the technical idea and field of the present invention.

[0014] Technical Solution

[0015] According to one embodiment, a matchless plasma source connected to a plasma chamber to supply radio frequency power of a first frequency to an electrode of the plasma chamber may include: a detector connected to a reaction circuit and configured to detect a radio frequency voltage or current at a terminal of the reaction circuit; the reaction circuit disposed at an output terminal of the matchless plasma source; and a controller connected to the reaction circuit and the detector and configured to calculate and control a tuning frequency, a pulse width, and a direct current (DC) voltage of the radio frequency power supplied by the matchless plasma source based on a reactance of the reaction circuit and the radio frequency voltage or current detected by the detector.

[0016] According to one embodiment, the present invention is characterized in that the controller is capable of controlling the RF signal generator further provided in the unmatched plasma source so as to generate the RF power having the controlled tuning frequency and pulse width.

[0017] According to yet another embodiment, the present invention is characterized in that the controller controls the reactance of the reaction circuit so that the reactance components of the reaction circuit and the plasma chamber are resonated in series or in parallel at the first frequency to function as a band pass filter (BPF).

[0018] According to another embodiment, the present invention is characterized in that the unmatched plasma source may further include a low-pass filter (LPF) or a band-pass filter (BPF) provided at an output end of the reaction circuit.

[0019] According to another embodiment, the present invention is characterized in that the unmatched plasma source further includes: a radio frequency signal generator for generating the radio frequency power; a frequency controller for adjusting the frequency of the radio frequency power according to the control of the controller; a pulse width controller for adjusting the pulse width of the radio frequency power according to the control of the controller; a DC power supply for supplying power to the unmatched plasma source; a gate driver connected to the radio frequency signal generator; and a power amplifier connected to the gate driver for amplifying the radio frequency power.

[0020] According to yet another embodiment, the present invention is characterized in that the controller is capable of controlling the DC voltage output from the DC power supply.

[0021] According to yet another embodiment, the present invention is characterized in that the output terminal of the power amplifier may include a half-bridge transistor circuit or a full-bridge transistor circuit.

[0022] According to yet another embodiment, the present invention is characterized in that the output terminal of the power amplifier may include a transistor circuit constructed in a SiC or GaN manner.

[0023] According to another embodiment, the present invention is characterized in that the output terminal of the power amplifier may include a transistor circuit configured in a Class E series or a Class CE series.

[0024] According to another embodiment, the present invention is characterized in that when the output end of the power amplifier includes a transistor circuit constructed in an E-series or CE-series manner, the DC power supply supplying power to the unmatched plasma source has a voltage-variable output characteristic.

[0025] According to one embodiment, the matchless plasma source in the operating method of the present invention includes: a reaction circuit connected to a plasma chamber and provided at an output end for supplying radio frequency power of a first frequency to an electrode of the plasma chamber; a detector connected to a front end or a rear end of the reaction circuit; and a controller connected to the reaction circuit and the detector. The operating method of the matchless plasma source is characterized by including: a detection step, in which the detector detects radio frequency voltage or current at an end of the reaction circuit; and a control step, in which the controller calculates and controls the tuning frequency, pulse width, and DC voltage of the radio frequency power provided by the matchless plasma source based on the reactance of the reaction circuit and the radio frequency voltage or current detected by the detector.

[0026] According to one embodiment, the present invention is characterized in that the controlling step is a step of controlling the RF signal generator so that the RF signal generator further provided in the unmatched plasma source generates the RF power having the controlled tuning frequency and pulse width.

[0027] According to another embodiment, the present invention is characterized in that the controlling step further includes the step of controlling the reactance of the reaction circuit so that the reactance components of the reaction circuit and the plasma chamber are resonated in series or in parallel at the first frequency to function as a band pass filter (BPF).

[0028] Effects of the Invention

[0029] According to one embodiment, a matched-free plasma source is proposed that controls an RF signal generator in a manner that generates RF power having a tuned frequency and pulse width controlled by the RF signal generator, while omitting an arbitrary waveform generator. This can achieve the technical effects of improving response speed and power efficiency, reducing price, and maximizing miniaturization.

[0030] However, the effects of the present invention are not limited to the above effects, and various extensions can be made without departing from the technical idea and field of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figures 1 to 4 A diagram for explaining a conventional unmatched plasma source.

[0032] Figure 5 FIG. 1 is a block diagram illustrating the concept of an unmatched plasma source according to an embodiment.

[0033] Figure 6 FIG. 1 is a diagram illustrating an unmatched plasma source according to an embodiment.

[0034] Figure 7 FIG. 1 is a flow chart illustrating a method for operating a non-matching plasma source according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following describes embodiments of the present invention in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The description of the present invention is merely an embodiment for implementing the structural description and even the functional description, and the scope of protection of the present invention should not be construed as being limited to the embodiments described in the specification.

[0036] That is, the present invention can be modified in many ways and can be embodied in many different implementations, and is not limited to the embodiments described herein. Therefore, it should be understood that the scope of protection claimed by the present invention includes equivalent technical solutions that can realize the technical idea.

[0037] On the other hand, the meanings of the terms described in the present invention should be understood as follows.

[0038] Terms such as "first" and "second" are used to distinguish one structural element from other structural elements, and the scope of protection claimed in the invention should not be limited to these terms. For example, a first structural element can be named a second structural element, and similarly, a second structural element can be named a first structural element.

[0039] When a structural element is referred to as being "connected to" another structural element, it may be directly connected to the other structural element, but it should also be understood that other structural elements may exist in between. Conversely, when a structural element is referred to as being "directly connected to" another structural element, it should be understood that no other structural elements exist in between. On the other hand, other expressions that describe the relationship between structural elements should also be interpreted in this way, that is, "between" and "directly between" or "adjacent to" and "directly adjacent to".

[0040] Unless otherwise clearly indicated in the context, expressions in the singular shall be understood to include expressions in the plural, and terms such as “including” or “having” shall be understood to be used to perform the existence of the implemented features, numbers, steps, actions, structural elements, parts or combinations thereof, and do not preclude the existence or additional possibility of one or more other features, numbers, steps, actions, structural elements, parts or combinations thereof.

[0041] In each step, identifiers (e.g., a, b, c, etc.) are used for ease of description and do not indicate the order of the steps. Unless a specific order is explicitly stated in the context, the steps can be performed in a different order than the stated order. That is, the steps can be performed in the same order as stated, performed simultaneously, or performed in reverse order.

[0042] Unless otherwise defined, all terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having the same meanings as those in the relevant art in context, and should not be interpreted as having idealized or overly formalized meanings unless explicitly defined in this invention.

[0043] It should be noted that the drawings illustrate the present invention in a simplified and non-proportional manner. The relative sizes and proportions of various components in the drawings are exaggerated or reduced in size for clarity and convenience. Any dimensions are illustrative only and are not limiting. Furthermore, identical structures, elements, or components shown in two or more drawings are assigned the same reference numerals to indicate similar features.

[0044] The embodiments of the present invention specifically illustrate idealized embodiments of the present invention. Therefore, various variations in the images are to be expected. Therefore, the embodiments are not limited to the specific embodiments shown and may include variations in form that result from, for example, manufacturing.

[0045] Hereinafter, a matchless plasma source and an operating method thereof will be described with reference to the accompanying drawings.

[0046] Figures 1 to 4 A diagram for explaining a conventional unmatched plasma source.

[0047] The structural elements and control method of the unmatched plasma source of one embodiment are different from those of the existing unmatched plasma source, but the purpose is the same. The working principle of the plasma source of one embodiment will be described below based on the working principle of the existing unmatched plasma source.

[0048] Because existing unmatched plasma sources implement arbitrary waveform generators by driving an amplitude modulation (AM) modulator in conjunction with a DC power supply, thereby rapidly changing the voltage of the DC power supply to the amplitude of high-frequency power, they have disadvantages such as slow response speed, low power efficiency, high price, and inability to maximize miniaturization.

[0049] To illustrate the existing unmatched plasma source, refer to Figure 2 The existing unmatched plasma source generates a shaped control signal to the arbitrary waveform generator on the controller board by offsetting the imaginary part of the transformer coupled plasma (TCP) coil impedance of the plasma chamber through a reaction circuit, thereby applying a signal to an agile direct current (DC) rail that also has the DC power supply function of a half-bridge field effect transistor (FET) circuit, thereby changing the size of the RF power output.

[0050] The basic concept of controlling such a conventional unmatched plasma source is based on the theory that when the plasma chamber side and the reaction circuit 322A are conjugate matched, the phases of the V / I input to the V / I probe 324 will be aligned.

[0051] That is, in the conventional unmatched plasma source, the high-frequency power generator and the impedance matching box are integrated into one body, and the functions of the high-frequency power generator and the impedance matching box are performed simultaneously.

[0052] but, Figure 2 The unmatched plasma source of the structure shown makes the voltage detection waveform of the V / I probe not ideal, and has the disadvantage of being difficult to find the optimal matching point.

[0053] Therefore, in order to solve Figure 2 The shortcomings of the structure shown are proposed Figure 3 The structure shown.

[0054] Figure 3 The structure shown is a structure in which the V / I probe is replaced by the I probe. Figure 3 The conventional unmatched plasma source shown can achieve matching by leaving only the R component, which is the real part, as a minimum impedance state when the transformer-coupled plasma (TCP) coil and the reaction circuit are conjugate-matched to each other. Then, the phases of the voltage and current are brought into an in-phase state, thereby transmitting maximum power to the plasma chamber.

[0055] have Figure 4 The existing unmatched plasma source with the structure shown also has Figure 2 、 Figure 3 The basic working principle and structure of the conventional unmatched plasma source are similar to those shown in the figure. Figure 4 The conventional non-matched plasma source of the structure shown can realize a non-matched plasma system by selectively using a V / I probe or an I probe to adjust the frequency of the clock and the voltage of the DC power supply.

[0056] The conventional unmatched plasma source described above has disadvantages such as slow response speed, low power efficiency, high price, and inability to maximize miniaturization because it quickly changes the voltage of the DC power supply to the amplitude of the high-frequency power.

[0057] Therefore, the following describes an embodiment of a matchless plasma source that uses a structure and method of controlling an RF signal generator to generate RF power having a tuned frequency and pulse width controlled by the RF signal generator.

[0058] Figure 5 FIG. 1 is a block diagram illustrating the concept of an unmatched plasma source according to an embodiment.

[0059] Reference Figure 5 In one embodiment, the unmatched plasma source includes a radio frequency signal generator 510, a DC power supply 520, a power amplifier 530, and a low-pass filter (LPF) or a band-pass filter 540 (BPF). The controller combined with the radio frequency signal generator 510 controls the tuning frequency and pulse width of the radio frequency power, thereby achieving the technical effects of improving response speed and power efficiency, reducing prices, and maximizing miniaturization.

[0060] In this case, the low-pass filter or the band-pass filter 540 may be omitted according to a specific example.

[0061] Figure 6 FIG. 1 is a diagram illustrating an unmatched plasma source according to an embodiment.

[0062] Reference Figure 6 In order to supply radio frequency power of a first frequency to an electrode of the plasma chamber 605 by being connected to the plasma chamber 605, the unmatched plasma source 600 of one embodiment may include: a reaction circuit 610, which is arranged at the output end of the unmatched plasma source 600; a detector 620, which is connected to the front end or the rear end of the reaction circuit; and a controller 630, which is connected to the reaction circuit 610 and the detector 620.

[0063] The detector 620 is a structural component that detects the RF voltage or current at the end of the reaction circuit 610 (as the output of the unmatched plasma source 600, the input or output of the reaction circuit 610) and transmits the detected RF voltage or current as a feedback signal to the controller 630. For example, it can be embodied as a V / I or I probe.

[0064] The controller 630 may calculate and control the tuning frequency, pulse width, and DC voltage of the RF power provided by the unmatched plasma source 600 based on the reactance of the reaction circuit 610 and the RF voltage or current detected by the detector 620 .

[0065] In more detail, the controller 630 can control the RF signal generator 640 , which is also provided in the unmatched plasma source 600 , so as to generate RF power having a controlled tuning frequency and pulse width.

[0066] Furthermore, in order to obtain better characteristics, the controller 630 may control the output voltage of the DC power supply 650 (the DC voltage output from the DC power supply 650 ) which is also provided in the unmatched plasma source 600 .

[0067] To this end, the unmatched plasma source 600 may further include: an RF signal generator 640 for generating RF power of RF signals with bandwidths of 400 kHz, 2 MHz, 13.56 MHz, 27 MHz, and 60 MHz; a frequency controller 631 for adjusting the frequency of the RF power according to the control of the controller 630; a pulse width controller 632 for adjusting the pulse width of the RF power according to the control of the controller 630; a DC power supply 650 for supplying power to the unmatched plasma source 600; a gate driver 660 connected to the RF signal generator 640; and a power amplifier 670 connected to the gate driver 660 for amplifying the RF power.

[0068] In this case, the output terminal of the power amplifier 670 may include a half-bridge transistor circuit or a full-bridge transistor circuit.

[0069] Furthermore, the output end of the power amplifier 670 may further include a transistor circuit constructed using SiC (silicon carbide) or GaN (gallium nitride).

[0070] Furthermore, the output end of the power amplifier 670 may further include a transistor circuit configured in a class E series or a class CE manner.

[0071] If the output end of the power amplifier 670 includes a transistor circuit configured in a class E series or a class CE manner, the DC power supply 650 may have a voltage-variable output characteristic.

[0072] In the above description, the controller 630 calculates the tuning frequency and pulse width of the RF power and controls the RF signal generator 640 and the DC power supply 650 . However, the present invention is not limited thereto. The controller 630 may control not only the RF signal generator 640 and the DC power supply 650 , but also the reaction circuit 610 .

[0073] For example, if merely controlling the tuning frequency and pulse width of the RF power of the RF signal generator 640 results in an insufficient matching range, the controller 630 may further control the reactance of the reaction circuit 610 .

[0074] According to a more specific example, the controller 630 may control the reactance of the reaction circuit 610 so that the reactance components of the reaction circuit 610 and the plasma chamber 605 are resonated in series or in parallel at a first frequency to function as a bandpass filter (BPF).

[0075] Furthermore, the unmatched plasma source 600 may further include a low-pass filter (LPF) or a band-pass filter (BPF) (not shown) disposed at the output end of the reaction circuit 610 .

[0076] Figure 7 FIG. 1 is a flow chart illustrating a method for operating a non-matching plasma source according to an embodiment of the present invention.

[0077] The following working method is based on Figures 5 and 6 An embodiment of the described structure is implemented as a premise without a matched plasma source.

[0078] Reference Figure 7 In step S710 , a detector may detect a radio frequency voltage or current at the reaction circuit end (output of the unmatched plasma source).

[0079] Therefore, the detected RF voltage or current can be transmitted to the controller as a feedback signal.

[0080] In step S720 , the controller may calculate and control the tuning frequency, pulse width, and DC voltage of the RF power supplied by the plasma source based on the reactance of the reaction circuit and the RF voltage or current detected by the detector.

[0081] In more detail, in step S720 , the controller can control the RF signal generator so that the RF signal generator further provided in the unmatched plasma source generates RF power having a controlled tuning frequency and pulse width.

[0082] If the matching range is insufficient only by controlling the tuning frequency and pulse width of the RF power of the RF signal generator in step S720 , the controller may further control the reactance of the reaction circuit.

[0083] For example, the controller may control the reactance of the reaction circuit so that the reactance components of the reaction circuit and the plasma chamber resonate in series or in parallel at a first frequency, which is the frequency of the RF power provided by the unmatched plasma source, thereby functioning as a bandpass filter.

[0084] Furthermore, in step S720 , the controller may control the DC voltage output from the DC power supply. DETAILED DESCRIPTION

[0085] As described above, although a number of embodiments have been described using a limited number of examples and figures, a person skilled in the art would be able to implement various modifications and variations based on the above description. For example, the described techniques may be performed in a different order than the described methods and / or the components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different manner than the described methods. Appropriate results may be achieved even if the components are replaced or substituted with other components or equivalents.

[0086] Therefore, contents equivalent to other embodiments, other examples, and the scope of protection of the invention belong to the scope of the appended invention claims.

Claims

1. An unmatched plasma source connected to a plasma chamber, supplying radio frequency power of a first frequency to an electrode of the plasma chamber, characterized in that: include: a detector connected to the reaction circuit and configured to detect a radio frequency voltage or current at an end of the reaction circuit; The reaction circuit is arranged at the output end of the unmatched plasma source; as well as A controller is connected to the reaction circuit and the detector, and calculates and controls the tuning frequency, pulse width, and DC voltage of the RF power supplied by the unmatched plasma source based on the reactance of the reaction circuit and the RF voltage or current detected by the detector.

2. The matchless plasma source according to claim 1, characterized in that The controller controls the RF signal generator, which is also provided in the unmatched plasma source, so as to generate the RF power having the controlled tuning frequency and pulse width.

3. The matchless plasma source according to claim 1, wherein: The controller controls the reactance of the reaction circuit so that reactance components of the reaction circuit and the plasma chamber are resonated in series or in parallel at the first frequency to function as a bandpass filter.

4. The matchless plasma source according to claim 1, wherein: The unmatched plasma source further includes a low-pass filter or a band-pass filter arranged at the output end of the reaction circuit.

5. The matchless plasma source according to claim 1, wherein: The unmatched plasma source further comprises: a radio frequency signal generator, configured to generate the radio frequency power; a frequency controller for adjusting the frequency of the radio frequency power according to control of the controller; a pulse width controller for adjusting the pulse width of the radio frequency power according to control of the controller; a DC power supply, configured to supply power to the unmatched plasma source; a gate driver connected to the radio frequency signal generator; and A power amplifier is connected to the gate driver and is used to amplify the radio frequency power.

6. The matchless plasma source according to claim 5, characterized in that: The controller controls the DC voltage output from the DC power supply.

7. The matchless plasma source according to claim 5, characterized in that: The output end of the power amplifier includes a half-bridge transistor circuit or a full-bridge transistor circuit.

8. The matchless plasma source according to claim 5, characterized in that: The output end of the power amplifier includes a transistor circuit constructed in a SiC or GaN manner.

9. The matchless plasma source according to claim 5, characterized in that: The output end of the power amplifier includes a transistor circuit constructed in a Class E series or a Class CE manner.

10. The matchless plasma source according to claim 9, characterized in that: In the case where the output end of the power amplifier includes a transistor circuit constructed in a class E series or a class CE manner, the DC power supply for supplying power to the unmatched plasma source has a voltage-variable output characteristic.

11. A method for operating an unmatched plasma source, wherein the unmatched plasma source comprises: a reaction circuit connected to the plasma chamber and provided at an output end for supplying radio frequency power of a first frequency to an electrode of the plasma chamber; a detector connected to a front end or a rear end of the reaction circuit; and a controller connected to the reaction circuit and the detector, wherein the working method of the unmatched plasma source is characterized by comprising: a detection step, wherein the detector detects the radio frequency voltage or current at the reaction circuit end; as well as In a control step, the controller calculates and controls the tuning frequency, pulse width, and DC voltage of the RF power provided by the unmatched plasma source based on the reactance of the reaction circuit and the RF voltage or current detected by the detector.

12. The method for operating a non-matching plasma source according to claim 11, wherein: The control step is a step of controlling the RF signal generator further provided in the unmatched plasma source so as to generate the RF power having the controlled tuning frequency and pulse width.

13. The operating method of the non-matching plasma source according to claim 11, characterized in that: The control step further includes controlling the reactance of the reaction circuit so that reactance components of the reaction circuit and the plasma chamber resonate in series or in parallel at the first frequency to function as a bandpass filter.

Images