Plasma control device and plasma processing system

Abstract

A plasma control device is provided, including: a plasma electrode disposed in a plasma chamber and having a radio frequency (RF) power of a fundamental frequency applied thereto to generate a plasma; an edge electrode disposed adjacent to the plasma electrode and corresponding to a plasma edge boundary region; and a plasma control circuit electrically connected to the edge electrode, the plasma control circuit being configured to control an electrical boundary condition in the plasma edge boundary region of a fundamental frequency component, a harmonic frequency component generated by nonlinearity of the plasma, and an intermodulation distortion frequency component generated by each of the fundamental frequency component and the harmonic frequency component and a frequency component in the plasma chamber, wherein the plasma control circuit is configured to change the electrical boundary condition to control a standing wave in the plasma chamber.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application 10-2021-0189669, filed on December 28, 2021, with the Korean Intellectual Property Office (KIPO), the entire contents of which are incorporated herein by reference. Technical Field

[0003] The example embodiments relate to plasma control devices and plasma processing systems. More specifically, the example embodiments relate to plasma control devices for controlling the distribution of plasma in a plasma chamber and plasma processing systems including the plasma control devices. Background Technology

[0004] In plasma processing systems, the uniformity of the plasma within the chamber can be a significant factor affecting processing performance. In particular, since high aspect ratio contact (HARC) etching equipment uses high frequencies as output power to generate sufficient density, the harmonic components of the primary frequency (fundamental frequency) and the intermodulation distortion (IMD) frequency components generated due to the nonlinearity of the plasma can have a substantial impact on the processing results. Summary of the Invention

[0005] One or more example embodiments provide a plasma control device configured to provide improved plasma uniformity within a plasma chamber.

[0006] One or more example embodiments also provide a plasma processing system including a plasma control device.

[0007] According to one aspect of an example embodiment, a plasma control device is provided, comprising: a plasma electrode disposed in a plasma chamber, wherein radio frequency (RF) power having a fundamental frequency is applied to the plasma electrode to generate plasma; an edge electrode disposed adjacent to the plasma electrode and corresponding to a plasma edge boundary region; and a plasma control circuit electrically connected to the edge electrode, the plasma control circuit being configured to control electrical boundary conditions in the plasma edge boundary region for a fundamental frequency component, harmonic components generated nonlinearly by the plasma, and intermodulation distortion frequency components generated by each of the fundamental frequency component and the harmonic components and frequency components in the plasma chamber, wherein the plasma control circuit is configured to change the electrical boundary conditions to control standing waves in the plasma chamber.

[0008] According to another aspect of the example embodiment, a plasma processing system is provided, comprising: a plasma chamber including plasma electrodes; a plasma power source configured to apply radio frequency (RF) power having a fundamental frequency to the plasma electrodes to generate plasma; an edge electrode disposed adjacent to the plasma electrodes and corresponding to a plasma edge boundary region; a plasma control circuit electrically connected to the edge electrodes, the plasma control circuit being configured to change electrical boundary conditions in the plasma edge boundary region based on an input control signal; a sensor configured to acquire electrical signal data of the edge electrodes; and a processor configured to acquire the electrical boundary conditions in the plasma edge boundary region based on the electrical signal data acquired by the sensor, and output a control signal to the plasma control circuit to acquire desired electrical boundary conditions.

[0009] According to another aspect of an example embodiment, a plasma processing system is provided, comprising: a plasma chamber providing a space configured to process a substrate; a substrate stage disposed within the plasma chamber to support the substrate, the substrate stage including a lower electrode; a plasma power source configured to apply radio frequency (RF) power having a fundamental frequency to the lower electrode to generate plasma; an edge electrode disposed adjacent to the lower electrode and configured to control electrical boundary conditions in a plasma edge boundary region; a plasma control circuit electrically connected to the edge electrode, the plasma control circuit being configured to change the electrical boundary conditions in the plasma edge boundary region by a fundamental frequency component, a harmonic component generated nonlinearly by the plasma, and an intermodulation distortion frequency component generated by each of the fundamental frequency component and the harmonic component and a frequency component in the plasma chamber; a sensor configured to acquire electrical signal data of the edge electrode; and a processor configured to acquire the electrical boundary conditions in the plasma edge boundary region based on the electrical signal data acquired by the sensor and to output a control signal to the plasma control circuit to acquire desired electrical boundary conditions. Attached Figure Description

[0010] The above and / or other aspects and features of this disclosure will become clearer by referring to the accompanying drawings, which describe exemplary embodiments of the present disclosure in detail, in which:

[0011] Figure 1 This is a block diagram illustrating a plasma processing system according to an example embodiment;

[0012] Figure 2 It shows Figure 1 Block diagram of the plasma control device in the image;

[0013] Figure 3 It shows Figure 2 The circuit diagram of the plasma control circuit in the image;

[0014] Figure 4 It shows Figure 1 A diagram of the high-frequency components within the plasma chamber;

[0015] Figure 5 It shows the connection to Figure 4 A circuit block diagram of the plasma control circuit for the edge electrodes in the circuit.

[0016] Figure 6 It is a graph showing the etch rate distribution based on the electrical boundary conditions in the edge boundary region;

[0017] Figure 7 This is a circuit block diagram showing the plasma control circuit of a plasma control device according to an example embodiment;

[0018] Figure 8 This is a flowchart illustrating a plasma processing method according to an example embodiment;

[0019] Figure 9 This is a block diagram illustrating a plasma processing system according to an example embodiment;

[0020] Figure 10 It shows Figure 9 A diagram of the high-frequency components in the plasma chamber; and

[0021] Figure 11 This is a block diagram illustrating a plasma processing system according to an example embodiment. Detailed Implementation

[0022] In the following text, exemplary embodiments will be described in detail with reference to the accompanying drawings.

[0023] It will be understood that when an element or layer is referred to as being "above," "over," "on," "below," "below," "connected to," or "coupled to" another element or layer, it may be directly above, above, above, below, below, or below that element or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as being "directly above," "over," "on," "below," "below," "below," "directly connected to," or "directly coupled to" another element or layer, there are no intermediate elements or layers.

[0024] Figure 1 This is a block diagram illustrating a plasma processing system according to an example embodiment. Figure 2 It shows Figure 1 Block diagram of the plasma control device. Figure 3 It shows Figure 2 The circuit diagram of the plasma control circuit. Figure 4 It shows Figure 1A diagram of the high-frequency components within the plasma chamber. Figure 5 It shows the connection to Figure 4 The circuit block diagram of the plasma control circuit for the edge electrode in the image.

[0025] refer to Figures 1 to 5 The plasma processing system 10 may include: a chamber 20 configured to provide space for performing plasma processing on a substrate such as a wafer W; a substrate stage 30 configured to support the substrate and having a lower electrode 40 and an upper electrode 50; and a plasma control device 100. Furthermore, the plasma processing system 10 may also include a plasma power supply, a gas supply, an exhaust system, etc. The plasma control device 100 may include an edge electrode 110, a sensor 120, a plasma control circuit 130, and a controller 140.

[0026] In an example embodiment, the plasma processing system 10 may be an apparatus configured to etch a target layer on a substrate, such as a semiconductor wafer W, disposed within a capacitively coupled plasma (CCP) chamber 20. However, the plasma generated by the plasma processing system is not limited to capacitively coupled plasma, and, for example, inductively coupled plasma may be generated by the plasma processing apparatus. Furthermore, the plasma processing system is not limited to etching apparatus, and, for example, may be used as a deposition apparatus, a cleaning apparatus, etc. Here, the substrate may include a semiconductor substrate, a glass substrate, etc.

[0027] Chamber 20 provides a sealed space for performing plasma etching on the wafer W. Chamber 20 can be, for example, a cylindrical vacuum chamber. Chamber 20 can include metals such as aluminum, stainless steel, etc. A door configured for loading and unloading the wafer W can be disposed in the sidewall of chamber 20. The wafer W can be loaded onto / unloaded from the substrate stage through this door.

[0028] An exhaust port can be located at the bottom of chamber 20, and the exhaust system can be connected to the exhaust port via an exhaust line. The exhaust system may include a vacuum pump (e.g., a turbomolecular pump) to control the pressure in the chamber, allowing the processing space inside chamber 20 to be depressurized to a desired vacuum level. Furthermore, processing byproducts and residual processing gases generated in chamber 20 can be discharged through the exhaust port.

[0029] A substrate stage 30 can be disposed within a chamber 20 to support a substrate. For example, the substrate stage 30 can serve as a base configured to support a wafer W located thereon. The substrate stage 30 may include a support plate 32 having electrostatic electrodes thereon for holding the wafer W using electrostatic force. The electrostatic electrodes can utilize electrostatic force to attract and hold the wafer W using a DC voltage supplied from a DC power supply. Furthermore, the support plate may have circulation channels therein for cooling. In addition, for precise wafer temperature control, a cooling gas such as helium (He) can be supplied between the electrostatic chuck and the wafer W.

[0030] The substrate stage 30 may include a disk-shaped lower electrode 40 mounted on a support plate 32. The substrate stage 30 may be mounted so as to be movable up and down via a drive mechanism. The lower electrode 40 may include a plate, a perforated plate, a screen, or any other distributed arrangement. The lower electrode 40 may include a sheet-type or mesh-type electrode.

[0031] In an example embodiment, a focusing ring 36 may be disposed adjacent to and surround the outer peripheral surface of the wafer W disposed on the support plate 32. The focusing ring 36 may be disposed on an outer insulating ring 34, which surrounds the substrate stage 30. The focusing ring 36 may have an annular shape to surround the wafer W. An edge electrode 110 may be disposed within the outer insulating ring 34. The edge electrode 110 may be disposed below the focusing ring 36. The edge electrode 110 may have an annular shape. The edge electrode 110 may be disposed adjacent to and surround the lower electrode 40, and may be arranged to be spaced apart from the lower electrode 40.

[0032] The lower electrode 40 can be disposed in a first region corresponding to the wafer W within the support plate 32, and the edge electrode 110 can be disposed in a second region corresponding to the peripheral region of the wafer W within the outer insulating ring 34 surrounding the support plate 32. The first region can be referred to as the central region PS1 of the plasma (or plasma sheath) region, and the second region can be referred to as the edge region PS2 of the plasma (or plasma sheath) region.

[0033] Edge electrode 110 may be in direct contact with focusing ring 36, or may be electrically connected to focusing ring 36. As described later, plasma control device 100 may be electrically connected to edge electrode 110 to form independent circuit paths through plasma control circuitry 130 in plasma edge boundary region EB. Electrical boundary conditions may be adjusted to change the electric field distribution of standing waves in chamber 20, thereby improving plasma uniformity. Furthermore, focusing ring 36 may prevent plasma from concentrating on the outer peripheral surface of wafer W during plasma processing of wafer W.

[0034] The substrate stage 30 may include a metallic or ceramic material. For example, the metallic or ceramic material may include at least one metal, a metal oxide, a metal nitride, a metal oxynitride, or a combination thereof. The substrate stage 30 may include aluminum, aluminum oxide, aluminum nitride, aluminum oxynitride, or a combination thereof.

[0035] The outer insulating ring 34 may have a structure that is adjacent to and surrounds the lower electrode 40. For example, the outer insulating ring 34 may include an insulating material (e.g., alumina). The focusing ring 36 may include a metal (e.g., aluminum) or an insulating material.

[0036] In an example embodiment, the plasma power source may include a first power source 60 configured to apply plasma source power to the downward electrode 40. For example, the first power source 60 may include an RF power source 62 and an RF matcher 64 as plasma source elements. The RF power source 62 may generate radio frequency (RF) signals.

[0037] RF power source 62 may include at least one source. For example, RF power source 62 may include a first source configured to generate RF power having a first frequency (fundamental frequency) in the range of several MHz to tens of MHz. Furthermore, RF power source 62 may also include a second source configured to generate RF power having a second frequency in a range lower than the first frequency. The high-frequency RF power from the first source can be used to generate plasma, while the low-frequency RF power from the second source can be used to supply energy to ions. However, embodiments are not limited thereto, and the RF power source may include three or more sources, and the low-frequency RF power may have various functions.

[0038] The RF matching unit 64 can match the impedance of the RF signal generated from the RF power source 62, so that the RF power can be optimally delivered to the plasma chamber 20. For example, the RF matching unit 64 can maximize the RF power delivery by adjusting the impedance based on the maximum power delivery theory to satisfy the complex conjugate condition.

[0039] RF matcher 64 may include two sub-matchers corresponding to each frequency of the RF power. For example, RF matcher 64 may include a first sub-matcher corresponding to a first frequency of a first source and a second sub-matcher corresponding to a second frequency of a second source.

[0040] A first transmission line 66 can be disposed between the first power supply 60 and the plasma chamber 20 to transmit RF power to the plasma chamber 20. The first transmission line 66 can electrically connect the first power supply 60 and the lower electrode 40. The first transmission line 66 can be implemented as, for example, a coaxial cable, an RF strip, an RF rod, etc. A coaxial cable can include a center conductor, an outer conductor, an insulator, and an outer sheath. A coaxial cable can have a structure in which the center conductor and the outer conductor are arranged coaxially.

[0041] The controller 140 can be connected to the first power supply 60 and the plasma control device 100 to control their operation. The controller, equipped with a microcomputer and various interface circuits, can control the operation of the plasma processing system based on program and method information stored in external or internal memory. For example, the controller 140 can output a second control signal S2 to the first power supply 60 to control RF frequency, RF transmission characteristics, etc. The controller 140 can include a simple controller, a microprocessor, a complex processor such as a central processing unit (CPU) or a graphics processing unit (GPU), a software-configurable processor, or dedicated hardware or firmware. For example, the controller 140 can be implemented by a general-purpose computer or a dedicated hardware component such as a digital signal processor (DSP), a field-programmable gate array (FPGA), or an application-specific integrated circuit (ASIC).

[0042] The upper electrode 50 can be positioned above the substrate stage 30, facing the lower electrode 40. The cavity space between the upper electrode 50 and the lower electrode 40 can be used as a plasma generation region. The upper electrode 50 can be connected to ground. According to another example embodiment, a second power source can be provided to supply RF power to the upper electrode 50. In this case, the upper electrode 50 can receive RF power from the second power source and can synchronously excite the source gas supplied to the cavity 20 into plasma with the lower electrode 40.

[0043] The upper electrode 50 may be configured as part of a nozzle for supplying gas into the chamber 20. The upper electrode 50 may include an electrode plate having a circular shape. The upper electrode 50 may be formed having a plurality of supply holes configured to supply gas into the chamber 20.

[0044] Specifically, the nozzle may support the upper electrode 50 and may include a nozzle body 70 configured to introduce gas supplied through the upper electrode 50 into the chamber 20. The nozzle body 70 may include a gas diffusion chamber 74, and the gas diffusion chamber 74 may be connected to an injection hole 72 formed in the nozzle body 70.

[0045] The gas supply may include a gas supply line 80, a flow controller 84, and a gas supply source 82 as gas supply elements. The gas supply line 80 can be connected to the gas diffusion chamber 74 of the nozzle body 70 through the supply port of the upper electrode 50, and the flow controller 84 can control the amount of gas supplied to the chamber 20 through the gas supply line 80. For example, the gas supply source 82 may include multiple gas tanks, and the flow controller 84 may include multiple mass flow controllers (MFCs) corresponding to the gas tanks respectively. The mass flow controllers can independently control the gas supply flow rate.

[0046] The first power source 60 can apply RF power to the lower electrode 40 to generate plasma from the process gas in the chamber 20 using the RF electric field formed on the lower electrode 40.

[0047] In an example embodiment, the plasma control device 100 can change the electrical boundary conditions in the plasma edge boundary region EB on the focusing ring 36 to control the standing wave in the plasma chamber, thereby controlling the plasma distribution over the entire region (center-middle-edge) of the wafer W.

[0048] Specifically, the plasma control circuit 130 can be electrically connected to the edge electrode 110 via the second transmission line 112. The plasma control circuit 130 can function as a reflector configured to change the electrical boundary conditions in the plasma edge boundary region EB in response to a first control signal S1 input from the controller 140. The plasma control circuit 130 can control the characteristic impedance of the edge region PS2 adjacent to the focusing ring 36 of the plasma (or plasma sheath) region to control the electrical boundary conditions in the plasma edge boundary region EB.

[0049] Sensor 120 can be mounted on the second transmission line 112 to acquire electrical signal data of the edge electrode 110. For example, sensor 120 may include a voltage-current sensor (VI sensor). The voltage-current measurement sensor can detect voltage (V), current (I), and phase of a first frequency component as well as harmonic and intermodulation distortion (IMD) components.

[0050] The controller 140 can calculate and obtain the electrical boundary conditions in the plasma edge boundary region EB based on the electrical signal data obtained by the sensor 120, and can output the first control signal S1 to the plasma control circuit 130 to obtain the desired electrical boundary conditions.

[0051] like Figure 4 As shown, when an RF component F1 with a first frequency (e.g., 60 MHz) is applied to the lower electrode 40, the RF component can move along its surface to generate plasma P in the plasma chamber 20. When RF power with the first frequency is applied to the plasma chamber 20, additional components (harmonic components, intermodulation distortion (IMD) frequency components) may be generated due to the nonlinearity of the plasma.

[0052] Some frequency components F2 of the high-frequency components present in the plasma sheath can travel toward the edge boundary region EB. The central region PS1 of the plasma sheath can have a first medium through a power supply circuit connected to the lower electrode 40, and the edge region PS2 of the plasma sheath can have a second medium different from the first medium through a plasma control circuit 130 connected to the edge electrode 110, wherein the edge boundary region EB is located between the central region PS1 and the edge region PS2.

[0053] Therefore, the frequency component F2 traveling to the edge boundary region EB can be partially reflected in the edge boundary region EB due to the difference between the first and second media, and some high-frequency components F3 can be reflected back into the plasma sheath, while some high-frequency components F4 can pass through and travel in parallel to the edge electrode 110. The traveling wave F2 traveling towards the edge boundary region EB in the plasma sheath and the reflected wave F3 reflected from the edge boundary region EB can intersect in the central region PS1 to form a standing wave. In the central region PS1 of the plasma sheath, the traveling wave and the reflected wave with the first frequency can intersect each other to form a standing wave, the traveling wave and the reflected wave with harmonic components can intersect each other to form a standing wave, and the traveling wave and the reflected wave with intermodulated frequency components can intersect each other to form a standing wave.

[0054] The amount and phase of the standing wave present in the central region PS1 of the plasma (or plasma sheath) can be adjusted to control the plasma distribution over the entire region (center-middle-edge) of the wafer W. The amount of reflection of high-frequency components in the plasma edge boundary region EB can be adjusted to control the amount and phase of the standing wave. The amount of reflection of high-frequency components in the plasma edge boundary region EB can be determined by the electrical boundary conditions in the edge boundary region EB. For example, the amount of reflection and transmission of traveling waves can be changed according to the electrical boundary conditions in the edge boundary region.

[0055] like Figure 2 and Figure 3 As shown, the plasma control circuit 130 may include an impedance control circuit configured to control the electrical boundary conditions of a first frequency component, a harmonic component, and an intermodulation frequency component in the plasma edge boundary region EB, wherein the harmonic component is generated nonlinearly by the plasma, and the intermodulation frequency component is generated by each of the first frequency component and the harmonic component and the frequency component in the plasma chamber.

[0056] The plasma control circuit 130 may include: a fundamental frequency control circuit 132 configured to change the electrical boundary conditions of a first frequency (fundamental wave); a first intermodulation frequency control circuit 136 configured to change the electrical boundary conditions of an intermodulation frequency component generated by the first frequency component and the frequency components in the plasma chamber; a harmonic frequency control circuit 134 configured to change the electrical boundary conditions of harmonic components; and a second intermodulation frequency control circuit 138 configured to change the electrical boundary conditions of an intermodulation frequency component generated by the harmonic components and the frequency components in the plasma chamber.

[0057] The fundamental frequency control circuit 132 and the harmonic frequency control circuit 134 can be connected in parallel to the edge electrode 110. The first intermodulation frequency control circuit 136 can be connected in series to the fundamental frequency control circuit 132. The second intermodulation frequency control circuit 138 can be connected in series to the harmonic frequency control circuit 134.

[0058] The baseband control circuit 132 may include a baseband resonant circuit configured to generate a resonance at a first frequency (fundamental wave). The baseband control circuit 132 may have a circuit structure in which a first inductor L1 and a first variable capacitor Cv1 are connected in parallel. The capacitance of the first variable capacitor Cv1 may be changed by a first control signal S11 from the controller 140 to determine the impedance Zh1 of the baseband resonant circuit. However, the embodiments are not limited thereto, and the baseband control circuit 132 may also have a circuit structure in which the first inductor L1 and the first variable capacitor Cv1 are connected in series.

[0059] The first intermodulation frequency control circuit 136 may include a first intermodulation frequency resonant circuit configured to generate a resonance at a first intermodulation frequency. The first intermodulation frequency control circuit 136 may have a circuit structure in which a second inductor L2 and a second variable capacitor Cv2 are connected in parallel. The capacitance of the second variable capacitor Cv2 may be changed by a first control signal S12 from the controller 140 to determine the impedance Zimd1 of the first intermodulation frequency resonant circuit. However, embodiments are not limited thereto, and the first intermodulation frequency control circuit 136 may have a circuit structure in which the second inductor L2 and the second variable capacitor Cv2 are connected in series.

[0060] The harmonic frequency control circuit 134 may include a harmonic frequency resonant circuit configured to generate a resonance at a harmonic frequency. The harmonic frequency control circuit 132 may have a circuit structure in which a third inductor L3 and a third variable capacitor Cv3 are connected in parallel. The capacitance of the third variable capacitor Cv3 may be changed by a first control signal S13 from the controller 140 to determine the impedance Zh2 of the harmonic frequency resonant circuit. However, the embodiments are not limited thereto, and the harmonic frequency control circuit 132 may also have a circuit structure in which the third inductor L3 and the third variable capacitor Cv3 are connected in series.

[0061] The second intermodulation frequency control circuit 138 may include a second intermodulation frequency resonant circuit configured to generate a second intermodulation frequency resonance. The second intermodulation frequency control circuit 138 may have a circuit structure in which a fourth inductor L4 and a fourth variable capacitor Cv4 are connected in parallel. The capacitance of the fourth variable capacitor Cv4 may be changed by a first control signal S14 from the controller 140 to determine the impedance Zimd2 of the second intermodulation frequency resonant circuit. However, the embodiments are not limited thereto, and the second intermodulation frequency control circuit 138 may also have a circuit structure in which the fourth inductor L4 and the fourth variable capacitor Cv4 are connected in series.

[0062] Furthermore, the plasma control circuit 130 may also include a first frequency blocking filter circuit 133 disposed before the harmonic frequency control circuit 134 to block the advance of the first frequency (fundamental frequency). For example, the first frequency blocking filter circuit 133 may have a circuit structure including a capacitor Cf connected in series and an inductor Lf connected in parallel.

[0063] It will be understood that the circuit structure of the plasma control circuit is not limited to this, and can be modified in various ways according to the overall circuit characteristics of the plasma control system and the characteristic impedance appearing in the edge boundary region.

[0064] The method for calculating and obtaining the reflection of high-frequency components in the plasma edge boundary region will be explained below.

[0065] like Figure 5 As shown, the amount of reflection in the plasma edge boundary region EB can be determined by the impedance Zc of the plasma control circuit 130. The controller 140 can calculate and obtain the electrical boundary conditions in the plasma edge boundary region EB based on the electrical signal data obtained by the sensor 120, and output the first control signal S1 to the plasma control circuit 130 to obtain the desired electrical boundary conditions (amount of reflection).

[0066] First, the electrical signal data (voltage Vc, current Ic, and phase) obtained from sensor 120 can be used as a basis. The impedance Zc of the plasma control circuit 130 is calculated and obtained, and the impedance Zc can be represented by the following equation (1).

[0067]

[0068] Edge electrode 110 can be electrically connected to plasma control circuit 130 via a transmission line with characteristic impedance Z0, serving as a load at one end of the transmission line (i.e., the second transmission line 112). In a structure transmitting high-frequency RF power, the impedance can vary depending on the length of the structure, as voltage and current values ​​change according to physical location (length). In this circuit structure, the impedance (Zedge) of edge electrode 110 can be represented by the input impedance equation as shown in equation (2), which is based on the load and characteristic impedance.

[0069]

[0070] Here, β is the phase constant (2π / λ).

[0071] The transmission line may have a first physical distance lc1 between the chamber 20 and the edge electrode 110 and a second physical distance lc2 between the plasma control circuit 130 and the chamber 20. Therefore, the characteristic impedance Z0 of the transmission line can be calculated by combining the impedances of the first physical distance lc1 and the second physical distance lc2. In this case, the characteristic impedance Z0, or the physical lengths lc1 and lc2, are constant values ​​determined by the configuration of the chambers. Thus, it can be seen that the impedance Zedge of the edge electrode 110 changes according to the impedance Zc of the plasma control circuit 130.

[0072] The amount of reflection Γ in the edge boundary region EB generated by the difference in electrical properties between the lower electrode 40 and the edge electrode 110 can be calculated by the following equation (3).

[0073]

[0074] Here, Zplasma is the impedance of the plasma.

[0075] Since the plasma impedance Zplasma is constant, it can be seen that the reflection Γ changes according to the impedance Zedge of the edge electrode 110. Therefore, the reflection Γ in the edge boundary region EB can be determined by the impedance Zc of the plasma control circuit 130.

[0076] Therefore, the controller 140 can calculate and obtain the electrical boundary conditions in the plasma edge boundary region EB based on the electrical signal data obtained by the sensor 120, and change the impedance (Zc) of the plasma control circuit 130 to obtain the desired electrical boundary conditions.

[0077] Figure 6 It is a graph showing the etch rate distribution based on the electrical boundary conditions in the edge boundary region.

[0078] refer to Figure 6Curve G1 shows the etching rate based on the wafer radius when the plasma control device 100 is not set, according to the relevant example, and curves G2, G3, and G4 show the etching rate based on the wafer radius when the plasma control device 100 is set, according to the exemplary embodiment. Curves G2, G3, and G4 are curves showing the etching rate distribution under different electrical boundary conditions in the plasma edge boundary region EB.

[0079] As shown in curve G2, regarding the etch rate distribution under the first electric boundary condition (EBC1), compared with the relevant example (curve G1), the etch rate at the center of the wafer can be reduced and the etch rate at the edge of the wafer can be increased to improve the plasma distribution across the entire region (center-middle-edge).

[0080] As shown in curve G3, regarding the etch rate distribution under the second electric boundary condition (EBC2), the etch rate at the center of the wafer can be reduced compared to the relevant example (curve G1) to improve the plasma distribution across the entire region (center-middle-edge).

[0081] As shown in curve G4, regarding the etch rate distribution under the third electric boundary condition (EBC3), the etch rate at the center, middle, and edge of the wafer can be increased compared to the relevant example (curve G1) to improve the plasma distribution across the entire region (center-middle-edge).

[0082] As described above, the plasma processing system 10 may include a plasma chamber 20 having a lower electrode 40 and a plasma control device 100, wherein the lower electrode 40 serves as a plasma electrode to which RF power having at least one fundamental frequency (first frequency) is applied, and the plasma control device 100 is configured to change the electrical boundary conditions in the plasma edge boundary region to control the standing wave in the plasma chamber. The plasma control device 100 may include an edge electrode 110 adjacent to and surrounding the lower electrode 40, and a plasma control circuit 130 electrically connected to the edge electrode 110 to change the electrical boundary conditions in response to an input control signal S1.

[0083] The plasma control circuit 130 can control the electrical boundary conditions in the plasma edge boundary region EB for the first frequency component, harmonic component and intermodulation frequency component, wherein the harmonic component is generated nonlinearly by the plasma, and the intermodulation frequency component is generated by each of the first frequency component and the harmonic component and the frequency component in the plasma cavity.

[0084] Therefore, the electric boundary conditions in the plasma edge boundary region EB can be changed to control the standing waves in the plasma chamber, thereby controlling the plasma distribution over the entire region (center-middle-edge) of the wafer W.

[0085] Figure 7 This is a circuit block diagram showing the plasma control circuit of a plasma control device according to an example embodiment. Figure 7 It shows Figure 2 The circuit block diagram of the plasma control circuit.

[0086] refer to Figure 7 The plasma control circuit 130 may include a filter control circuit configured to control the electrical boundary conditions of a first frequency component, a harmonic component, and an intermodulation frequency component in the plasma edge boundary region EB, wherein the harmonic component is generated nonlinearly by the plasma, and the intermodulation frequency component is generated by each of the first frequency component and the harmonic component and the frequency component in the plasma chamber.

[0087] The plasma control circuit 130 may include: a fundamental frequency control circuit 132 configured to change the electrical boundary conditions of a first frequency (fundamental wave); a first intermodulation frequency control circuit 136 configured to change the electrical boundary conditions of an intermodulation frequency component generated by the first frequency component and the frequency components in the plasma chamber; a harmonic frequency control circuit 134 configured to change the electrical boundary conditions of harmonic components; and a second intermodulation frequency control circuit 138 configured to change the electrical boundary conditions of an intermodulation frequency component generated by the harmonic frequency component and the frequency components in the plasma chamber.

[0088] Each of the fundamental frequency control circuit 132, the first intermodulation frequency control circuit 136, the harmonic frequency control circuit 134, and the second intermodulation frequency control circuit 138 may include a bandpass filter (BPF) connected in series with each other and a switch for switching the operation of each bandpass filter. These switches may be turned on and off by second control signals S11, S12, S13, and S14 from the controller 140, respectively. The controller 140 may function as a filter control circuit that selectively operates the bandpass filters via switches to allow only a specific range of frequencies to pass through.

[0089] The use of will be explained below. Figure 1 A method for processing a substrate using a plasma processing system.

[0090] Figure 8 This is a flowchart illustrating a plasma processing method according to an example embodiment.

[0091] refer to Figures 1 to 8An edge electrode 110 (S100) can be configured to control the electrical boundary conditions in the plasma edge boundary region EB.

[0092] In an example embodiment, the edge electrode 110 may be disposed adjacent to and surrounding the support plate 32 of the substrate stage 30 within an outer insulating ring 34. The edge electrode 110 may be disposed below a focusing ring 36 having an annular shape surrounding the wafer W. The edge electrode 110 may have an annular shape. The edge electrode 110 may be disposed adjacent to and surrounding the lower electrode 40 in the support plate 32, and may be arranged to be spaced apart from the lower electrode.

[0093] The lower electrode 40 can be disposed in a first region corresponding to the wafer W within the support plate 32, and the edge electrode 110 can be disposed in a second region corresponding to the peripheral region of the wafer W within the outer insulating ring 34 surrounding the support plate 32. The first region can be referred to as the central region PS1 of the plasma (or plasma sheath) region, and the second region can be referred to as the edge region PS2 of the plasma (or plasma sheath) region.

[0094] The plasma control circuit 130, which is configured to change the electrical boundary conditions in the edge boundary region EB, can be electrically connected to the edge electrode 110 (S110).

[0095] The plasma control circuit 130 can be electrically connected to the edge electrode 110 to form an independent circuit path. The plasma control circuit 130 can change the electrical boundary conditions in response to the input control signal S1.

[0096] Specifically, the plasma control circuit 130 may include an impedance control circuit or a filter control circuit configured to control the electrical boundary conditions in the plasma edge boundary region EB of the first frequency component, the harmonic components generated by the nonlinearity of the plasma, and the intermodulation frequency components generated by each of the first frequency component and the harmonic components and the frequency components in the plasma chamber.

[0097] Then, RF power with a first frequency (RF frequency) for plasma generation can be supplied to the plasma chamber 20 (S120).

[0098] like Figure 4 As shown, the first power supply 60 can supply an RF component F1 having a first high frequency (e.g., 60 MHz) to the lower electrode 40. This RF component can move along the surface of the substrate stage 30 including the lower electrode 40 to form plasma P in the plasma chamber 20. When RF power having the first frequency is applied to the plasma chamber 20, additional components (harmonic components, intermodulation distortion (IMD) frequency components) may be generated due to the nonlinearity of the plasma.

[0099] Some frequency components F2 of the high-frequency components present in the plasma sheath can travel toward the edge boundary region EB in the plasma sheath. The central region PS1 of the plasma sheath can have a first medium through a power supply circuit connected to the lower electrode 40, and the edge region PS2 of the plasma sheath can have a second medium different from the first medium through a plasma control circuit 130 connected to the edge electrode 110, wherein the edge boundary region EB is between the central region PS1 and the edge region PS2.

[0100] Therefore, the frequency component F2 traveling to the edge boundary region EB can be partially reflected in the edge boundary region EB due to the difference between the first and second media, and some high-frequency components F3 can be reflected back into the plasma sheath, while some high-frequency components F4 can pass through and travel in parallel to the edge electrode 110. The traveling wave F2 traveling towards the edge boundary region EB in the plasma sheath and the reflected wave F3 reflected from the edge boundary region EB can intersect in the central region PS1 to form a standing wave. In the central region PS1 of the plasma sheath, the traveling wave and the reflected wave with the first frequency can intersect each other to form a standing wave, the traveling wave and the reflected wave with harmonic components can intersect each other to form a standing wave, and the traveling wave and the reflected wave with intermodulated frequency components can intersect each other to form a standing wave.

[0101] Then, the voltage and current information of the edge electrode 110 can be obtained in real time to calculate and obtain the electric boundary conditions in the edge boundary region (S130), and the electric boundary conditions in the boundary region EB can be changed by plasma control circuit 130 based on the calculated electric boundary conditions (S140).

[0102] In an example embodiment, sensor 120 may be mounted on the second transmission line 112 to acquire electrical signal data of the edge electrode 110. For example, sensor 120 may include a voltage-current sensor (VI sensor). The voltage-current measurement sensor can detect voltage (V), current (I), and phase at a first frequency, as well as harmonic and intermodulation distortion (IMD) components.

[0103] The controller 140 can calculate and obtain the electrical boundary conditions in the plasma edge boundary region EB based on the electrical signal data obtained by the sensor 120, and output the first control signal S1 to the plasma control circuit 130 to obtain the desired electrical boundary conditions.

[0104] For example, the amount of reflection Γ (boundary condition) in the edge boundary region EB generated by the difference in electrical characteristics between the lower electrode 40 and the edge electrode 110 can be determined by the impedance Zc of the plasma control circuit 130.

[0105] The plasma control circuit 130 can be used as a reflector, which is configured to change the electrical boundary conditions in the plasma edge boundary region EB in response to a first control signal S1 input from the controller 140.

[0106] Therefore, the amount and phase of the standing wave can be controlled by controlling the amount of reflection of the high-frequency components in the plasma edge boundary region EB. Thus, the amount and phase of the standing wave present in the central region PS1 of the plasma (plasma sheath) can be changed to control the plasma distribution over the entire region (center-middle-edge) of the wafer W.

[0107] Figure 9 This is a block diagram illustrating a plasma processing system according to an example embodiment. Figure 10 It shows Figure 9 A diagram showing the high-frequency components in the plasma chamber. Aside from the arrangement of the plasma power supply and plasma control devices, this plasma processing system can be integrated with a reference... Figures 1 to 5 The plasma processing systems described are substantially the same or similar. Therefore, the same reference numerals will be used to refer to the same or similar elements, and any further repetitive descriptions of the aforementioned elements will be omitted.

[0108] refer to Figure 9 and Figure 10 The plasma power source of the plasma processing system 11 may include a second power source 70 configured to apply plasma source power to the upward electrode 50.

[0109] In an example embodiment, the second power supply 70 may include an RF power source 72 and an RF matching unit 74, which are plasma source elements. The RF power source 72 can generate radio frequency (RF) signals. A first transmission line 76 may be disposed between the second power supply 70 and the plasma chamber 20 to transmit RF power to the plasma chamber 20. The second power supply may be connected to... Figure 1 The first power sources in these systems are essentially the same or similar. Therefore, their detailed description will be omitted.

[0110] The lower electrode 40 can be connected to ground. According to another example embodiment, a first power source can be configured to supply RF power to the lower electrode 40. In this case, the lower electrode 40 can receive RF power from the first power source and can synchronously excite the source gas supplied to the chamber 20 into plasma with the upper electrode 50.

[0111] In an example embodiment, the edge electrode 110 may be disposed within an outer insulating ring 22, which is located in the upper portion of the chamber 20 adjacent to and surrounding the nozzle body 70. The outer insulating ring 22 may have a structure surrounding the nozzle body 70. For example, the outer insulating ring 22 may comprise an insulating material (e.g., alumina). The edge electrode 110 may have an annular shape. The edge electrode 110 may surround the upper electrode 50 and may be arranged spaced apart from the upper electrode. However, the embodiment is not limited thereto, and the edge electrode 110 may be disposed in an outer region within the nozzle body 70.

[0112] The upper electrode 50 can be disposed in a first region corresponding to the wafer W within the nozzle body 70, and the edge electrode 110 can be disposed in a second region corresponding to the outer region of the wafer W within the upper part of the chamber 20 surrounding the nozzle body 70. The first region can be referred to as the central region PS1 of the plasma (or plasma sheath) region, and the second region can be referred to as the edge region PS2 of the plasma (or plasma sheath) region.

[0113] Plasma control circuit 130 can be electrically connected to edge electrode 110 via second transmission line 112. Plasma control circuit 130 can function as a reflector configured to change the electrical boundary conditions in plasma edge boundary region EB in response to a first control signal S1 input from controller 140. Plasma control circuit 130 can change the characteristic impedance of the edge region PS2 of the plasma (or plasma sheath) region adjacent to edge electrode 110 to control the electrical boundary conditions in plasma edge boundary region EB.

[0114] like Figure 10 As shown, when an RF component F1 with a first high frequency (e.g., 60 MHz) is supplied to the upward electrode 50, this component can move along the surface, thereby generating plasma P in the plasma chamber 20. When RF power with the first frequency is applied to the plasma chamber 20, additional components (harmonic components, intermodulation distortion (IMD) frequency components) may be generated due to the nonlinearity of the plasma.

[0115] Some frequency components F2 of the high-frequency components present in the plasma sheath can travel toward the edge boundary region EB. The central region PS1 of the plasma sheath can have a first medium through a power supply circuit connected to the upper electrode 50, and the edge region PS2 of the plasma sheath can have a second medium different from the first medium through a plasma control circuit 130 connected to the edge electrode 110, wherein the edge boundary region EB is located between the central region PS1 and the edge region PS2.

[0116] Therefore, some frequency components F2 traveling to the edge boundary region EB can be reflected in the edge boundary region EB due to the difference between the first and second media, and some high-frequency components F3 can be reflected back into the plasma sheath, while some high-frequency components F4 can pass through and travel in parallel to the edge electrode 110. The traveling wave F2 traveling towards the edge boundary region EB in the plasma sheath and the reflected wave F3 reflected from the edge boundary region EB can intersect in the central region PS1 to form a standing wave. In the central region PS1 of the plasma sheath, the traveling wave and the reflected wave with the first frequency can intersect each other to form a standing wave, the traveling wave and the reflected wave with harmonic components can intersect each other to form a standing wave, and the traveling wave and the reflected wave with intermodulated frequency components can intersect each other to form a standing wave.

[0117] The plasma control circuit 130 of the plasma control device can control the electric boundary conditions in the plasma edge boundary region of the first frequency component, the harmonic component generated by the nonlinearity of the plasma, and the intermodulation frequency component generated by each of the first frequency component and the harmonic component and the frequency component in the plasma chamber.

[0118] This plasma control device can be connected with Figure 1 The plasma control devices in these systems are essentially the same or similar. Therefore, a detailed description of them will be omitted.

[0119] Figure 11 This is a block diagram illustrating a plasma processing system according to an example embodiment. Apart from the arrangement of the plasma power source, this plasma processing system can be integrated with a reference... Figures 1 to 5 The plasma processing systems described are substantially the same or similar. Therefore, the same reference numerals will be used to refer to the same or similar elements, and any further repetitive descriptions of the aforementioned elements will be omitted.

[0120] refer to Figure 11 The plasma power source of the plasma processing system 12 may include a second power source 70 configured to apply plasma source power to the upward electrode 50.

[0121] In an example embodiment, the second power source 70 may include an RF power source 72 and an RF matching device 74, which are plasma source elements. The RF power source 72 can generate radio frequency (RF) signals. The second power source 70 can be connected to... Figure 1 The first power sources in these systems are essentially the same or similar. Therefore, their detailed description will be omitted.

[0122] The lower electrode 40 can be connected to ground. Alternatively, a first power source can be configured to supply RF power to the lower electrode 40. In this case, the lower electrode 40 can receive RF power from the first power source and can synchronously excite the source gas supplied to the chamber 20 into plasma with the upper electrode 50.

[0123] In an example embodiment, the edge electrode 110 may be disposed within the outer insulating ring 34. The edge electrode 110 may be disposed below the focusing ring 36. The edge electrode 110 may have an annular shape. The edge electrode 110 may be disposed adjacent to and surrounding the lower electrode 40, and may be arranged to be spaced apart from the lower electrode.

[0124] The upper electrode 50 can be disposed in a first region corresponding to the wafer W within the nozzle 70, and the edge electrode 110 can be disposed in a second region corresponding to the peripheral region of the wafer W within an outer insulating ring 34 surrounding the support plate 32. The first region can be referred to as the central region PS1 of the plasma (or plasma sheath) region, and the second region can be referred to as the edge region PS2 of the plasma (or plasma sheath) region.

[0125] The edge electrode 110 can directly contact the focusing ring 36 or be electrically connected to the focusing ring 36. The plasma control device 100 can control the electric boundary conditions in the plasma edge boundary region EB through the plasma control circuit 130 electrically connected to the edge electrode 110, so as to provide an independent circuit path to change the electric field distribution of the standing wave in the chamber 20, thereby improving the uniformity of the plasma.

[0126] This plasma control device can be connected with Figure 1 The plasma control devices in these systems are essentially the same or similar. Therefore, a detailed description of them will be omitted.

[0127] The plasma processing apparatus and method described above can be used to manufacture semiconductor devices, including logic devices and memory devices. For example, semiconductor devices can be applied to logic devices (e.g., central processing unit (CPU), main processing unit (MPU), or application processor (AP), etc.), as well as volatile memory devices (e.g., DRAM devices, SRAM devices) or non-volatile memory devices (e.g., flash memory devices, PRAM devices, MRAM devices, ReRAM devices, etc.).

[0128] Although exemplary embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope defined by the appended claims and their equivalents.

Claims

1. A plasma control device, comprising: Plasma electrodes are disposed in a plasma chamber, and radio frequency (RF) power with a fundamental frequency is applied to the plasma electrodes to generate plasma; An edge electrode is disposed adjacent to the plasma electrode and corresponds to the plasma edge boundary region; as well as A plasma control circuit, electrically connected to the edge electrode, is configured to control the electrical boundary conditions in the plasma edge boundary region of the fundamental frequency component, the harmonic components generated nonlinearly by the plasma, and the intermodulation distortion frequency components generated by each of the fundamental frequency component and the harmonic components and the frequency components in the plasma chamber. The plasma control circuit is configured to change the electrical boundary conditions to control the standing waves in the plasma chamber.

2. The plasma control device according to claim 1, wherein, The edge electrode has a ring shape.

3. The plasma control device according to claim 1, wherein, The plasma electrode includes a lower electrode disposed in a substrate stage, the substrate stage being configured to support a substrate in the plasma chamber.

4. The plasma control device according to claim 3, wherein, The edge electrode is disposed adjacent to the lower electrode in the outer region of the substrate stage.

5. The plasma control device according to claim 3, further comprising: A focusing ring extending along the periphery of the substrate on the edge electrode.

6. The plasma control device according to claim 5, wherein, The edge electrode is electrically connected to the focusing ring.

7. The plasma control device according to claim 6, further comprising: A sensor is configured to acquire electrical signal data from the edge electrodes; as well as The processor is configured as follows: Based on the electrical signal data obtained by the sensor, the electrical boundary conditions in the plasma edge boundary region are obtained; and A control signal is output to the plasma control circuit to obtain the desired electrical boundary conditions.

8. The plasma control device according to claim 7, wherein, The electrical signal data obtained by the sensor includes voltage, current, and phase.

9. The plasma control device according to claim 7, wherein, The sensor includes a voltage and current sensor.

10. The plasma control device according to claim 1, wherein, The plasma control circuit includes: The fundamental frequency control circuit is configured to change the electrical boundary conditions of the fundamental frequency component; The first intermodulation frequency control circuit is configured to change the electrical boundary conditions of the intermodulation distortion frequency components generated by the frequency components in the plasma chamber and the fundamental frequency components. A harmonic frequency control circuit is configured to change the electrical boundary conditions of the harmonic components; and The second intermodulation frequency control circuit is configured to change the electrical boundary conditions of the intermodulation distortion frequency components generated by the frequency components and harmonic components in the plasma chamber.

11. A plasma processing system, comprising: Plasma chamber, including plasma electrodes; A plasma power source is configured to apply radio frequency (RF) power with a fundamental frequency to the plasma electrodes to generate plasma; An edge electrode is disposed adjacent to the plasma electrode and corresponds to the plasma edge boundary region; A plasma control circuit, electrically connected to the edge electrode, is configured to change the electrical boundary conditions in the plasma edge boundary region based on an input control signal. A sensor is configured to acquire electrical signal data from the edge electrodes; as well as The processor is configured to obtain electrical boundary conditions in the plasma edge boundary region based on the electrical signal data obtained by the sensor, and to output the control signal to the plasma control circuit to obtain the desired electrical boundary conditions.

12. The plasma processing system according to claim 11, wherein, The edge electrode has a ring shape.

13. The plasma processing system according to claim 11, wherein, The plasma electrode includes at least one of an upper electrode and a lower electrode.

14. The plasma processing system according to claim 13, wherein, When the plasma electrode includes the lower electrode, the edge electrode is disposed adjacent to the lower electrode.

15. The plasma processing system according to claim 14, further comprising: A focusing ring extending along the periphery of the substrate on the edge electrode.

16. The plasma processing system according to claim 15, wherein, The edge electrode is electrically connected to the focusing ring.

17. The plasma processing system according to claim 11, wherein, The plasma control circuit includes: A baseband control circuit is configured to change the electrical boundary conditions of the baseband. The first intermodulation frequency control circuit is configured to change the electrical boundary conditions of the intermodulation distortion frequency components generated by the frequency components in the plasma chamber and the fundamental frequency. The harmonic frequency control circuit is configured to change the electrical boundary conditions of the harmonic components; and The second intermodulation frequency control circuit is configured to change the electrical boundary conditions of the intermodulation distortion frequency components generated by the frequency components and harmonic components in the plasma chamber.

18. The plasma processing system according to claim 17, wherein, The plasma control circuit includes an impedance control circuit or a filter control circuit.

19. The plasma processing system according to claim 11, wherein, The electrical signal data obtained by the sensor includes voltage, current, and phase.

20. The plasma processing system according to claim 11, wherein, The sensor includes a voltage and current sensor.

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