Matchless plasma source and method of operation thereof

Abstract

A matchless plasma source and a method for operating the same are provided. The matchless plasma source according to one embodiment includes a detector connected to a reactive circuit and detecting an RF voltage or current from the reactive circuit terminal, the reactive circuit disposed at an output terminal of the matchless plasma source, and a controller connected to the reactive circuit and the detector and calculating and controlling a tuning frequency, pulse width, and DC voltage of RF power provided by the matchless plasma source based on the reactance of the reactive circuit and the RF voltage or current detected by the detector.

Description

[Technical Field]

[0001] The present disclosure relates to a plasma source for use in a plasma processing apparatus and a method of operating the same. [Background technology]

[0002] Plasma processing equipment is used as a core device in semiconductor processing processes for etching, depositing, and cleaning pure semiconductor wafers.

[0003] Generally, a plasma processing apparatus is composed of a plasma chamber, an RF generator that generates RF power, and an impedance matcher that matches the output impedance of the RF generator with the impedance of the plasma chamber to supply maximum power and minimize power loss in the plasma chamber.

[0004] Conventionally, plasma processing equipment has typically been constructed by connecting a physically separate high-frequency power generator, impedance matching device, and plasma chamber with coaxial cables or the like. However, this type of structure can cause problems such as instability due to mismatching and transmission loss.

[0005] To address these issues, an integrated structure has been proposed that integrates a high-frequency power generator, an impedance matching box, and a plasma chamber. Such integrated structures are disclosed in Patent Documents 1, 2, and 3.

[0006] The integrated structure achieves a matching effect by canceling out the jX component, which is the imaginary part of the equivalent circuit impedance of the plasma chamber, R + jX, by adjusting the impedance of the reactive circuit and the RF frequency of the signal generator, leaving only the real R component, and then bringing the voltage and current in phase to transmit maximum power to the plasma chamber.

[0007] At this time, the RF output can be adjusted by the voltage of the arbitrary waveform generator, so that the integrated structure generates and provides any output waveform through the arbitrary waveform generator.

[0008] That is, in the integrated structure, the role of the conventional impedance matching device is taken on by the reactive circuit and voltage adjustment method, making it possible to simplify and miniaturize the device.

[0009] However, the integrated structure has drawbacks such as slow response speed, low power efficiency, high cost, and inability to maximize miniaturization, because it uses an arbitrary waveform generator that is provided separately from the RF signal generator that generates RF power to suddenly change the voltage of the DC power supply to the amplitude of the high frequency output power.

[0010] This has created a need for techniques to overcome the shortcomings of such integrated structures. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Korean Patent Publication No. 10-2020-0059310 [Patent Document 2] Korean Patent Publication No. 10-2020-0121909 [Patent Document 3] Korean Patent Publication No. 10-2021-0034059 Summary of the Invention [Problem to be solved by the invention]

[0012] In one embodiment, in order to improve response speed and power efficiency, reduce cost, and maximize miniaturization, an arbitrary waveform generator is omitted, and a matchless plasma source is proposed in which an RF signal generator controls the RF signal generator to generate RF power with a controlled tuning frequency and pulse width.

[0013] However, the technical problem to be solved by the present invention should not be limited thereto, and may be variously expanded within the scope that does not deviate from the technical idea and scope of the present invention. [Means for solving the problem]

[0014] According to one embodiment, a matchless plasma source connected to a plasma chamber and providing RF power of a first frequency to an electrode of the plasma chamber may include a detector connected to a reactive circuit and detecting an RF voltage or current at the reactive circuit end, the reactive circuit disposed at an output end of the matchless plasma source, and a controller connected to the reactive circuit and the detector and calculating and controlling the tuning frequency, pulse width, and DC voltage of the RF power provided by the matchless plasma source based on the reactance of the reactive circuit and the RF voltage or current detected by the detector.

[0015] According to one aspect, the controller may be characterized by controlling an RF signal generator further included in the matchless plasma source so that the RF signal generator generates the RF power having the controlled tuning frequency and pulse width.

[0016] According to another aspect, the controller may be characterized by controlling the reactance of the reactive circuit so that the reactance components of the reactive circuit and the plasma chamber are resonated in series or parallel at the first frequency to perform the role of a band pass filter (BPF).

[0017] According to another aspect, the matchless plasma source may further include a low pass filter (LPF) or a band pass filter (BPF) disposed at an output end of the reactive circuit.

[0018] According to another aspect, the matchless plasma source may further include an RF signal generator that generates the RF power, a frequency controller that adjusts the frequency of the RF power under control of the controller, a pulse width controller that adjusts the pulse width of the RF power under control of the controller, a DC power supply that supplies power to the matchless plasma source, a gate driver connected to the RF signal generator, and a power amplifier connected to the gate driver that amplifies the RF power.

[0019] According to another aspect, the controller may control a DC voltage output from the DC power supply.

[0020] According to another aspect, the output end of the power amplifier may include a half-bridge transistor circuit or a full-bridge transistor circuit.

[0021] According to another aspect, the output terminal of the power amplifier may include a transistor circuit made of SiC or GaN.

[0022] According to another aspect, the output terminal of the power amplifier may include a transistor circuit configured in a Class E series or Class CE system.

[0023] According to yet another aspect, a DC power supply that supplies power to the matchless plasma source may be characterized by having a variable voltage output characteristic when the output terminal of the power amplifier includes a transistor circuit configured in a Class E series or Class CE system.

[0024] According to one embodiment, a method for operating a matchless plasma source including a reactive circuit disposed at an output end in a state connected to a plasma chamber to provide RF 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 reactive circuit, and a controller connected to the reactive circuit and the detector may include a step in which the detector detects an RF voltage or current at the reactive circuit end, and a step in which the controller calculates and controls the tuning frequency, pulse width, and DC voltage of the RF power provided by the matchless plasma source based on the reactance of the reactive circuit and the RF voltage or current detected by the detector.

[0025] According to one aspect, the controlling step may be characterized as a step of controlling an RF signal generator further included in the matchless plasma source so that the RF signal generator generates the RF power having the controlled tuning frequency and pulse width.

[0026] According to another aspect, the controlling step may further include controlling the reactance of the reactive circuit so that the reactance components of the reactive circuit and the plasma chamber are resonated in series or parallel at the first frequency to function as a band pass filter (BPF). [Effects of the Invention]

[0027] One embodiment proposes a matchless plasma source in which an RF signal generator is controlled to generate RF power having a controlled tuning frequency and pulse width, without using an arbitrary waveform generator, thereby achieving technical effects of improving response speed and power efficiency, reducing cost, and maximizing miniaturization.

[0028] However, the effects of the present invention should not be limited to this, and may be variously expanded within the scope of the technical idea and scope of the present invention. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram for explaining a conventional matchless plasma source. [Figure 2] FIG. 1 is a diagram for explaining a conventional matchless plasma source. [Figure 3] FIG. 1 is a diagram for explaining a conventional matchless plasma source. [Figure 4] FIG. 1 is a diagram for explaining a conventional matchless plasma source. [Figure 5] FIG. 1 is a block diagram illustrating the concept of a matchless plasma source in one embodiment. [Figure 6] FIG. 1 illustrates a matchless plasma source in one embodiment. [Figure 7] 1 is a flow chart illustrating a method of operating a matchless plasma source in one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The description of the present invention is merely an example for explaining the structure or function, and the scope of the present invention should not be construed as being limited by the examples described herein.

[0031] In other words, the present invention is susceptible to various modifications and can be implemented in various different forms, and therefore should not be limited to the embodiments described herein, and the scope of the rights of the present invention should be interpreted as including equivalents that can realize the technical idea.

[0032] Meanwhile, the meanings of the terms used in the present invention should be understood as follows.

[0033] Terms such as "first" and "second" are used merely to distinguish one component from another, and should not be used to limit the scope of rights. For example, the first component may be named the second component, and the second component may be named the first component.

[0034] When a component is described as being "connected" to another component, it should be understood that this includes not only the case where it is directly connected to the other component, but also the case where there are other components between them. Conversely, when a component is described as being "directly connected" to another component, it should be understood that there are no other components between them. Other expressions describing the relationship between components, such as "between," "immediately between," "adjacent to," and "directly adjacent to," should be interpreted in the same way.

[0035] Singular expressions should be understood to include plural expressions unless the context clearly dictates otherwise. Furthermore, terms such as "comprise" or "have" are intended to specify the presence of embodied features, numbers, steps, operations, components, parts, or combinations thereof, and should be understood as not precluding the possible presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0036] The identification numbers (e.g., a, b, c, etc.) in each step are used for convenience of description and do not dictate the order of each step, and each step may be performed in a different order from the order described unless the context clearly dictates a specific order. That is, each step may be performed in the same order as described, substantially simultaneously, or in the reverse order.

[0037] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted in accordance with the meaning they have in the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless expressly defined in this invention.

[0038] The drawings are schematic and not drawn to scale. Relative dimensions and proportions of parts shown in the drawings have been exaggerated or reduced for clarity and convenience of the drawings, and any dimensions are illustrative only and not limiting. Furthermore, identical structures, elements, or parts shown in multiple drawings have been designated with the same reference numerals to indicate similarities in features.

[0039] The embodiments of the present invention specifically show ideal examples of the present invention, and therefore various modifications of the illustrations are expected. Therefore, the embodiments should not be limited to the specific shapes of the regions shown in the drawings, and also include modifications of the shapes due to manufacturing, for example.

[0040] A matchless plasma source and its method of operation will now be described with reference to the accompanying drawings.

[0041] 1 to 4 are diagrams for explaining a conventional matchless plasma source.

[0042] Although the matchless plasma source according to an embodiment has different components and control methods from conventional matchless plasma sources, the purpose is the same. Therefore, the operating principle of the plasma source according to an embodiment will be described below based on the operating principle of conventional matchless plasma sources.

[0043] Conventional matchless plasma sources realize an arbitrary waveform generator by using an AM modulator coupled to a DC power supply, and because the voltage of the DC power supply is suddenly changed to the amplitude of the high frequency output power, they have drawbacks such as slow response speed, low power efficiency, high cost, and difficulty in maximizing miniaturization.

[0044] To illustrate a conventional matchless plasma source, referring to Figure 2, a conventional matchless plasma source modifies the RF power output in addition to the agile DC rail, which together serve as the DC power supply for the half-bridge FET circuit, by generating a shaped control signal using an arbitrary waveform generator on the controller board to cancel the imaginary part of the TCP coil impedance of the plasma chamber in a reactive circuit.

[0045] The basic concept behind the control of such conventional matchless plasma sources is based on the theory that when the plasma chamber side and the reactive circuit 322A are conjugate matched, the V / I phase input to the VI probe 324 will match.

[0046] That is, in the conventional matchless plasma source, a high frequency power generator and an impedance matching device are integrated into one unit, and the high frequency power generator and the impedance matching device simultaneously perform their respective functions.

[0047] However, the matchless plasma source with the structure shown in Figure 2 had the drawback that the voltage detection waveform of the V / I probe did not appear ideally, making it difficult to find the optimum matching point.

[0048] Therefore, in order to solve the drawbacks of the structure shown in FIG. 2, a structure as shown in FIG. 3 has been proposed.

[0049] The structure shown in Figure 3 replaces the V / I probe with an I probe. In the conventional matchless plasma source shown in Figure 3, when the TCP coil and reactive circuit are conjugate matched with each other, only the real part, the R component, is left to create a minimum impedance state, and then the voltage and current phases are brought into an in-phase state, transmitting maximum power to the plasma chamber to perform matching.

[0050] The conventional matchless plasma source having the structure shown in Figure 4 has the same basic operating principle and components as the conventional matchless plasma sources shown in Figures 2 and 3. The conventional matchless plasma source having the structure shown in Figure 4 realizes a matchless plasma system by selectively using a V / I probe and an I probe to adjust the clock frequency and the voltage of the DC supply unit.

[0051] Such conventional matchless plasma sources have drawbacks such as slow response speed, low power efficiency, high cost, and inability to maximize miniaturization because they rapidly change the voltage of the DC power supply to the amplitude of the high frequency output power.

[0052] Therefore, the following describes one embodiment of a matchless plasma source that employs a structure and method for controlling an RF signal generator so that the RF signal generator generates RF power having a controlled tuning frequency and pulse width (or conduction angle).

[0053] FIG. 5 is a block diagram illustrating the concept of a matchless plasma source in one embodiment.

[0054] Referring to FIG. 5, a matchless plasma source according to one embodiment includes an RF signal generator 510, a DC power supply 520, a power amplifier 530, and a low pass filter (LPF) or a band pass filter (BPF) 540. The tuning frequency and pulse width of the RF power are controlled by a controller coupled to the RF signal generator 510, thereby achieving technical effects of improving response speed and power efficiency, reducing costs, and maximizing miniaturization.

[0055] In this case, the low-pass filter or band-pass filter 540 may be omitted depending on the embodiment.

[0056] FIG. 6 is a diagram illustrating a matchless plasma source in one embodiment.

[0057] Referring to FIG. 6, a matchless plasma source 600 according to one embodiment may include a reactive circuit 610 disposed at an output end of the matchless plasma source 600 to provide RF power of a first frequency to an electrode of the plasma chamber 605 while connected to the plasma chamber 605, a detector 620 connected to the front or rear end of the reactive circuit, and a controller 630 connected to the reactive circuit 610 and the detector 620.

[0058] The detector 620 is a component that detects an RF voltage or current from the reactive circuit 610 end (the output of the matchless plasma source 600, and the input or output of the reactive circuit 610) and transmits the detected RF voltage or current as a feedback signal to the controller 630, and may be realized, for example, by a V / I or I probe.

[0059] The controller 630 may calculate and control the tuning frequency and pulse width of the RF power and DC voltage provided by the matchless plasma source 600 based on the reactance of the reactive circuit 610 and the RF voltage or current detected from the detector 620.

[0060] More specifically, the controller 630 may control the RF signal generator 640, further included in the matchless plasma source 600, so that the RF signal generator 640 generates RF power having a controlled tuning frequency and pulse width (or conduction angle).

[0061] In addition, the controller 630 may control the output voltage of a DC power supply 650 (a DC voltage output from the DC power supply 650) that is further included in the matchless plasma source 600 in order to obtain better characteristics.

[0062] For this purpose, the matchless plasma source 600 may further include an RF signal generator 640 that generates RF power, which is an RF signal in the 400 kHz, 2 MHz, 13.56 MHz, 27 MHz, or 60 MHz band, a frequency controller 631 that adjusts the frequency of the RF power under the control of the controller 630, a pulse width controller 632 that adjusts the pulse width (or conduction angle) of the RF power under the control of the controller 630, a DC power supply 650 that supplies power to the matchless 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 that amplifies the RF power.

[0063] In this case, the output terminal of the power amplifier 670 may include a half-bridge transistor circuit or a full-bridge transistor circuit.

[0064] Additionally, the output of the power amplifier 670 may include a transistor circuit constructed using SiC or GaN technology.

[0065] The output terminal of the power amplifier 670 may include a transistor circuit configured in a Class E or Class CE format.

[0066] When the output terminal of the power amplifier 670 includes a transistor circuit configured in a Class E series or Class CE system, the DC power supply 650 may have a variable voltage output characteristic.

[0067] In the above, the controller 630 has been described as calculating the tuning frequency and pulse width of the RF power to control the RF signal generator 640 and the DC power supply 650, but this is not intended to be limiting or restrictive, and the controller 630 may control not only the RF signal generator 640 and the DC power supply 650 but also the reactive circuit 610.

[0068] For example, the controller 630 may control the reactance of the reactive circuit 610 when the matching range is not sufficient by simply controlling the tuning frequency and pulse width of the RF power of the RF signal generator 640 .

[0069] As a more specific example, the controller 630 may control the reactance of the reactive circuit 610 so that the reactive components of the reactive circuit 610 and the plasma chamber 605 are serially or parallel resonated at the first frequency to perform the role of a band pass filter (BPF).

[0070] Furthermore, the matchless 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 reactive circuit 610.

[0071] FIG. 7 is a flow chart illustrating a method of operating a matchless plasma source in one embodiment.

[0072] The method of operation described below is assumed to be performed by a matchless plasma source according to one embodiment, the structure of which is described with reference to FIGS.

[0073] Referring to FIG. 7, in step 710, a detector may detect an RF voltage or current from the reactive circuit end (the output of the matchless plasma source).

[0074] Thereby, the detected RF voltage or current may be transmitted to the controller as a feedback signal.

[0075] In step 720, the controller may calculate and control the tuning frequency and pulse width of the RF power and DC voltage provided by the plasma source based on the reactance of the reactive circuit and the RF voltage or current detected from the detector.

[0076] More specifically, in step 720, the controller may control an RF signal generator further included in the matchless plasma source so that the RF signal generator generates RF power having a controlled tuning frequency and pulse width.

[0077] In step 720, if the matching range is not sufficient by controlling the tuning frequency and pulse width of the RF power of the RF signal generator, the controller may also control the reactance of the reactive circuit.

[0078] For example, the controller may control the reactance of the reactive circuit so that the reactive components of the reactive circuit and the plasma chamber are resonated in series or parallel at a first frequency, which is the frequency of the RF power provided by the matchless plasma source, thereby performing the role of a bandpass filter.

[0079] Additionally, in step 720, the controller may control the DC voltage output from the DC power supply.

[0080] Although the embodiments have been described above based on limited examples and drawings, those skilled in the art will appreciate that various modifications and variations may be made from the above description. For example, the described techniques may be performed in an order different from that described, and / or the described system, structure, device, circuit, or other element may be coupled or combined in a manner different from that described, or may be substituted or replaced by other elements or equivalents, and still achieve suitable results.

[0081] Therefore, different embodiments are within the scope of the appended claims, provided that they are equivalent to the claims.

Claims

1. a matchless plasma source connected to a plasma chamber and supplying RF power of a first frequency to an electrode of the plasma chamber, a detector connected to the reactive circuit for detecting RF voltage or current from the reactive circuit; the reactive circuit disposed at the output end of the matchless plasma source; a controller connected to the reactive circuit and the detector, which calculates and controls a tuning frequency, a pulse width, and a DC voltage of the RF power provided by the matchless plasma source based on the reactance of the reactive circuit and the RF voltage or current detected by the detector; a matchless plasma source, including

2. The controller 2. The matchless plasma source of claim 1, further comprising an RF signal generator that controls the RF signal generator to generate the RF power having the controlled tuning frequency and pulse width.

3. The controller 2. The matchless plasma source of claim 1, wherein the reactance of the reactive circuit is controlled so that the reactive components of the reactive circuit and the plasma chamber are resonated in series or parallel at the first frequency to function as a band pass filter (BPF).

4. The matchless plasma source comprises: A low pass filter (LPF) or a band pass filter (BPF) disposed at the output end of the reactive circuit.

10. The matchless plasma source of claim 1 further comprising:

5. The matchless plasma source comprises: an RF signal generator that generates the RF power; a frequency controller that adjusts the frequency of the RF power according to the control of the controller; a pulse width controller that adjusts the pulse width of the RF power according to the control of the controller; a DC power supply for powering the matchless plasma source; a gate driver connected to the RF signal generator; a power amplifier connected to the gate driver for amplifying the RF power; 10. The matchless plasma source of claim 1 further comprising:

6. The controller 6. The matchless plasma source according to claim 5, wherein the DC voltage output from the DC power supply is controlled.

7. The output terminal of the power amplifier is 6. The matchless plasma source of claim 5, comprising a half-bridge transistor circuit or a full-bridge transistor circuit.

8. The output terminal of the power amplifier is 6. The matchless plasma source of claim 5, comprising a transistor circuit constructed of SiC or GaN.

9. The output terminal of the power amplifier is 6. The matchless plasma source according to claim 5, comprising a transistor circuit configured in a Class E series or Class CE system.

10. The DC power supply that supplies power to the matchless plasma source includes:

10. The matchless plasma source according to claim 9, wherein the output terminal of the power amplifier has a variable voltage output characteristic when the output terminal includes a transistor circuit configured in a Class E series or Class C-E system.

11. 1. A method for operating a matchless plasma source, comprising: a reactive circuit disposed at an output end connected to the plasma chamber to supply RF 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 reactive circuit; and a controller connected to the reactive circuit and the detector, the detector detecting an RF voltage or current from the reactive circuit end; the controller calculating and controlling a tuning frequency, a pulse width, and a DC voltage of RF power provided by the matchless plasma source based on the reactance of the reactive circuit and the RF voltage or current detected by the detector; A method of operating a matchless plasma source, comprising:

12. The controlling step includes:

12. The method of operating a plasma source of claim 11, further comprising the step of controlling an RF signal generator included in the matchless plasma source to generate the RF power having the controlled tuning frequency and pulse width.

13. The controlling step includes: controlling the reactance of the reactive circuit so that the reactive components of the reactive circuit and the plasma chamber are serially or parallel resonated at the first frequency to function as a band pass filter (BPF); 12. The method of operating a matchless plasma source of claim 11, further comprising:

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