Substrate processing apparatus and substrate processing method

Abstract

The present inventive concept provides a substrate processing apparatus and a substrate processing method. The substrate processing apparatus includes a process chamber having a processing space therein, a support unit for supporting a substrate in the process chamber, a gas supply unit for supplying a process gas inside the process chamber, and a plasma generation unit for generating plasma from the process gas, wherein the plasma generation unit includes a top electrode disposed above the substrate, a bottom electrode disposed below the substrate, an edge electrode disposed at an edge surrounding the substrate, three high-frequency power sources applying high-frequency power to the bottom electrode, and an edge impedance control circuit connected to the edge electrode.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2020-0186249, filed with the Korean Intellectual Property Office on December 29, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments of the inventive concept described herein relate to a substrate processing apparatus and a substrate processing method. Background Technology

[0004] Semiconductor manufacturing processes can include processes that use plasma to treat substrates. For example, during semiconductor manufacturing, etching processes can use plasma to remove thin films from a substrate. Plasma refers to an ionized gas state generated by very high temperatures, strong electric fields, or high-frequency electromagnetic fields, and composed of ions, electrons, or free radicals. In semiconductor manufacturing, plasma is used to perform etching processes. The etching process is performed by colliding ion particles contained in the plasma with the substrate.

[0005] For example, capacitively coupled plasma (CCP) sources can be used for plasma generation. When performing high aspect ratio (HAR) etching in a CCP-type plasma source, it is necessary to increase the radio frequency (RF) power to obtain a high ion energy distribution (IED). However, at higher RF powers, RF problems such as arcing are common. Therefore, an alternative method for increasing IED is needed. Summary of the Invention

[0006] Embodiments of the present invention provide a substrate processing apparatus and method capable of achieving high aspect ratio and high ion energy distribution.

[0007] The technical objectives of this invention are not limited to those mentioned above, and other unmentioned technical objectives will become apparent to those skilled in the art from the following description.

[0008] The present invention provides a substrate processing apparatus. The substrate processing apparatus includes a process chamber having a processing space; a support unit for supporting a substrate within the process chamber; a gas supply unit for supplying process gases into the process chamber; and a plasma generation unit for generating plasma from the process gases. The plasma generation unit includes: a top electrode disposed above the substrate; a bottom electrode disposed below the substrate; an edge electrode disposed at an edge surrounding the substrate; three high-frequency power supplies that apply high-frequency power to the bottom electrode; and an edge impedance control circuit connected to the edge electrode.

[0009] In one embodiment, the three high-frequency power supplies include: a first frequency power supply; a second frequency power supply; and a third frequency power supply; wherein the first frequency power supply has a range between 100 kHz and 400 kHz.

[0010] In one embodiment, the second frequency power supply has a range between 2 MHz and 10 MHz.

[0011] In one embodiment, the third frequency power supply has a range of 60 MHz or higher.

[0012] In one embodiment, the edge impedance control circuit has one or more notch filters and a variable capacitor connected in series with the one or more notch filters.

[0013] In one embodiment, the edge impedance control circuit has one or more notch filters and a high-pass filter connected in series with the one or more notch filters.

[0014] In one embodiment, one or more notch filters block frequencies within the range of the first and second frequency power supplies, and a variable capacitor controls the impedance of the third frequency power supply.

[0015] In one embodiment, one or more notch filters block frequencies within the range of the first and second frequency power supplies, and a high-pass filter controls the impedance of the third frequency power supply and shunts the harmonics of the third frequency power supply.

[0016] The present invention provides a substrate processing apparatus. The substrate processing apparatus includes a process chamber having a processing space; a support unit for supporting a substrate within the process chamber; a gas supply unit for supplying process gases into the process chamber; and a plasma generation unit for generating plasma from the process gases. The plasma generation unit includes: a top electrode disposed above the substrate; a bottom electrode disposed below the substrate; three high-frequency power supplies that apply high-frequency power to the bottom electrode; and the support unit includes: an edge ring surrounding the substrate; a coupling ring disposed below the edge ring and including an edge electrode within the coupling ring; and an edge impedance control circuit connected to the edge electrode.

[0017] In one embodiment, the three high-frequency power supplies include: a first frequency power supply; a second frequency power supply; and a third frequency power supply; wherein the first frequency power supply has a range between 100 kHz and 400 kHz.

[0018] In one embodiment, the second frequency power supply has a range between 2 MHz and 10 MHz.

[0019] In one embodiment, the third frequency power supply has a range of 60 MHz or higher.

[0020] In one embodiment, the edge impedance control circuit has one or more notch filters and a variable capacitor connected in series with the one or more notch filters.

[0021] In one embodiment, the edge impedance control circuit has one or more notch filters and a high-pass filter connected in series with the one or more notch filters.

[0022] In one embodiment, the one or more notch filters block frequencies within the range of the first and second frequency power supplies, and the variable capacitor controls the impedance of the third frequency power supply.

[0023] In one embodiment, one or more notch filters block frequencies within the range of the first and second frequency power supplies, and a high-pass filter controls the impedance of the third frequency power supply and shunts the harmonics of the third frequency power supply.

[0024] The present invention provides a substrate processing method that uses a substrate processing apparatus to generate plasma within a process chamber. The substrate processing method includes controlling a first frequency of a first frequency power supply and a second frequency of a second frequency power supply without controlling a third frequency of a third frequency power supply applied to the bottom electrode; and blocking the first and second frequencies while controlling a high-frequency impedance for the third frequency.

[0025] In one embodiment, the high-frequency impedance for controlling the third frequency includes a tuning edge impedance control circuit.

[0026] In one embodiment, the first frequency has a range of 100 kHz and 400 kHz, and the second frequency is controlled within the range of 2 MHz to 10 MHz.

[0027] In one embodiment, the first frequency is controlled to decrease from a first value to a second value lower than the first value.

[0028] According to the concept of the present invention, it is possible to obtain a high aspect ratio and a high ion energy distribution.

[0029] The effects of the inventive concept are not limited to those described above, and those skilled in the art will clearly understand from this specification and the accompanying drawings any effects not mentioned. Attached Figure Description

[0030] Referring to the following figures, the above and other objects and features will become apparent from the following description, wherein, unless otherwise specified, the same reference numerals throughout the figures refer to the same parts, and wherein:

[0031] Figure 1 This is a view illustrating a substrate processing apparatus according to an embodiment of the present invention.

[0032] Figure 2 This is a further enlarged view of a substrate processing apparatus according to an embodiment of the present invention.

[0033] Figures 3A to 3B This is a view illustrating the ion energy distribution in a substrate processing apparatus according to an embodiment of the present invention.

[0034] Figure 4 This is a view showing the ion energy distribution when the first frequency is changed in a substrate processing apparatus according to an embodiment of the present invention.

[0035] Figure 5 This is a view showing the sloping profile of the 3D-NAND etching due to low ion energy.

[0036] Figure 6 A view to explain the formation of the total driving force of ions.

[0037] Figures 7A to 7B A view illustrating an edge impedance control circuit according to an embodiment of the present invention. Detailed Implementation

[0038] The inventive concept can be modified and takes many forms, and specific embodiments of the inventive concept will be shown and described in detail in the accompanying drawings. However, the embodiments conceived according to the inventive concept are not intended to limit the specific forms disclosed, and it should be understood that the inventive concept includes all variations, equivalents, and substitutions contained within the spirit and scope of the inventive concept. In the description of the inventive concept, detailed descriptions of relevant known technologies may be omitted where such detailed descriptions might obscure the essence of the inventive concept.

[0039] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the inventive concept. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well. It will also be understood that, as used in this specification, the terms “comprise” and / or “comprising” indicate the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Furthermore, the term “exemplary” is intended to refer to embodiments or examples.

[0040] It will be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or section from another. Therefore, without departing from the teachings of the inventive concept, the first element, component, region, layer, or section discussed below may be referred to as a second element, component, region, layer, or section.

[0041] In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0042] Figure 1 An exemplary view is shown of a substrate processing apparatus according to an embodiment of the present invention.

[0043] Figure 1A substrate processing apparatus using a capacitively coupled plasma (CCP) processing method is shown. (Reference) Figure 1 The substrate processing apparatus 10 uses plasma to process the substrate S. For example, the substrate processing apparatus 10 can perform an etching process on the substrate S. The substrate processing apparatus 10 may include a chamber 100, a substrate support assembly 200, a plasma generation unit 300, a gas supply unit 400, and a partition unit 500.

[0044] Chamber 100 provides a processing space in which substrate processing processes are performed. Chamber 100 may have a processing space therein, and chamber 100 may be configured in a sealed shape. Chamber 100 may be made of a metallic material. Chamber 100 may be made of aluminum. Chamber 100 may be grounded. A vent 102 may be formed on the bottom surface of chamber 100. Vent 102 may be connected to a vent line 151. Reaction byproducts generated during the process and gaseous residues in the internal space of the chamber can be vented to the outside through the vent line 151. The internal pressure of chamber 100 can be depressurized to a predetermined pressure through a venting process.

[0045] According to one embodiment, a liner 130 may be disposed inside the chamber 100. The liner 130 may have a cylindrical shape with an open top surface and an open bottom surface. The liner 130 may be configured to contact the inner surface of the chamber 100. The liner 130 can protect the inner wall of the chamber 100 from damage by arc discharge. Furthermore, it can prevent impurities generated during substrate processing from depositing on the inner wall of the chamber 100.

[0046] The substrate support assembly 200 can be positioned inside the chamber 100. The substrate support assembly 200 can support the substrate S. The substrate support assembly 200 may include an electrostatic chuck that uses electrostatic force to attract the substrate S. Alternatively, the substrate support assembly 200 can support the substrate S in various ways, such as mechanical clamping. The substrate support assembly 200 including the electrostatic chuck will be described below.

[0047] The substrate support assembly 200 may include an electrostatic chuck, a bottom cover 250, and a plate 270. The substrate support assembly 200 may be positioned within the chamber 100 and spaced upward from the bottom surface of the chamber 100.

[0048] An electrostatic chuck may include a dielectric plate 220, a body 230, and a focusing ring 240. The electrostatic chuck may support a substrate S.

[0049] The dielectric plate 220 can be positioned at the top end of the electrostatic chuck. The dielectric plate 220 can be configured as a disk-shaped dielectric material. The substrate S can be disposed on the top surface of the dielectric plate 220. The top surface of the dielectric plate 220 can have a radius smaller than the radius of the substrate S. Therefore, the edge region of the substrate S can be located outside the dielectric plate 220.

[0050] The dielectric plate 220 may include a first electrode 223, a heater 225, and a first supply fluid channel 221. The first supply fluid channel 221 may be disposed from the top surface of the dielectric plate 220 to the bottom surface of the dielectric plate 220. A plurality of first supply fluid channels 221 are formed to be spaced apart from each other and may be configured as a passage through which a heat transfer medium is supplied to the bottom surface of the substrate S.

[0051] The first electrode 223 can be electrically connected to a first power supply 223a. The first power supply 223a may include a direct current (DC) power supply. A switch 223b may be installed between the first electrode 223 and the first power supply 223a. The first electrode 223 can be electrically connected to the first power supply 223a by turning the switch 223b on / off. When the switch 223b is on, a direct current (DC) current can be applied to the first electrode 223. The current applied to the first electrode 223 applies an electrostatic force between the first electrode 223 and the substrate S, and the substrate S can be attracted to the dielectric plate 220 by this electrostatic force.

[0052] Heater 225 may be located below first electrode 223. Heater 225 may be electrically connected to second power supply 225a. Heater 225 can generate heat by resisting current applied from second power supply 225a. The generated heat can be transferred to substrate S through dielectric plate 220. Substrate S can be maintained at a predetermined temperature by the heat generated by heater 225. Heater 225 may include a helical coil.

[0053] The main body 230 can be positioned below the dielectric plate 220. The bottom surface of the dielectric plate 220 and the top surface of the main body 230 can be bonded together by adhesive 236. The main body 230 can be made of aluminum. The top surface of the main body 230 can be stepped, such that the central region is positioned higher than the edge regions. The central region of the top surface of the main body 230 has an area corresponding to the bottom surface of the dielectric plate 220 and can be adhered to the bottom surface of the dielectric plate 220. The main body 230 can have a first circulating fluid channel 231, a second circulating fluid channel 232, and a second supply fluid channel 233 formed therein.

[0054] The first circulating fluid channel 231 can be configured as a channel through which the heat transfer medium circulates. The first circulating fluid channel 231 can be formed in a spiral shape within the main body 230. Alternatively, the first circulating fluid channel 231 can be configured such that annular channels with different radii have the same center. Each of the first circulating fluid channels 231 can be interconnected. The first circulating fluid channels 231 can be formed at the same height. The second circulating fluid channel 232 can be configured as a channel through which the cooling fluid circulates. The second circulating fluid channel 232 can be formed in a spiral shape within the main body 230. Alternatively, the second circulating fluid channel 232 can be configured such that annular channels with different radii have the same center. Each of the second circulating fluid channels 232 can be interconnected. The second circulating fluid channel 232 can have a cross-sectional area larger than that of the first circulating fluid channel 231. The second circulating fluid channel 232 can be formed at the same height. The second circulating fluid channel 232 can be located below the first circulating fluid channel 231.

[0055] The second supply fluid channel 233 can extend upward from the first circulation fluid channel 231 and can be disposed on the top surface of the body 230. The number of second supply fluid channels 233 can correspond to the number of first supply fluid channels 221, and the first circulation fluid channels 231 can be connected to the first supply fluid channels 221.

[0056] The first circulating fluid channel 231 can be connected to the heat transfer medium storage unit 231a via a heat transfer medium supply line 231b. The heat transfer medium can be stored in the heat transfer medium storage unit 231a. The heat transfer medium may include an inert gas. According to one embodiment, the heat transfer medium may include helium (He). Helium can be supplied to the first circulating fluid channel 231 via the supply line 231b, and can be supplied to the bottom surface of the substrate S sequentially via the second supply fluid channel 233 and the first supply fluid channel 221. Helium can be used as a medium through which heat transferred from the plasma to the substrate S is transferred to the electrostatic chuck.

[0057] The second circulating fluid channel 232 can be connected to the cooling fluid storage unit 232a via the cooling fluid supply line 232c. Cooling fluid can be stored in the cooling fluid storage unit 232a. A cooler 232b can be disposed within the cooling fluid storage unit 232a. The cooler 232b can cool the cooling fluid to a predetermined temperature. Alternatively, the cooler 232b can be installed at the cooling fluid supply line 232c. The cooling fluid supplied to the second circulating fluid channel 232 via the cooling fluid supply line 232c can circulate along the second circulating fluid channel 232 to cool the main body 230. The main body 230 can together cool the dielectric plate 220 and the substrate S to maintain the substrate S at a predetermined temperature.

[0058] The body 230 may include a metal plate. The body 230 may serve as a bottom electrode. In this case, the body 230 is connected to a bottom power supply unit. The bottom power supply unit supplies power to the body 230, i.e., the bottom electrode. The bottom power supply unit includes three bottom power supplies 236a, 237a, and 238a, and a matching unit 235. In one embodiment, two of the three bottom power supplies may be a first frequency power supply 236a and a second frequency power supply 237a having a frequency of 10 MHz or lower, and the other bottom power supply may be a third frequency power supply 238a having a frequency of 10 MHz or higher. Switches 236b, 237b, and 238b may be connected to each of the three bottom power supplies 236a, 237a, and 238a to be electrically connected to the bottom electrode according to the on / off state of the switches 236b, 237b, and 238b. The first frequency power supply 236a and the second frequency power supply 237a can control ion energy, and the third frequency power supply 238a can control plasma density. Matching unit 225 is electrically connected to the first frequency power supply to the third frequency power supply 236a, 237a and 238a, and supplies different amounts of frequency power to the body 230, which serves as the bottom electrode, by matching the frequency power.

[0059] A focusing ring 240 can be disposed in the edge region of the electrostatic chuck. The focusing ring 240 can have an annular shape and can be disposed around the dielectric plate 220. The top surface of the focusing ring 240 can be stepped, such that the outer surface 240a is higher than the inner surface 240b. The inner surface 240b of the top surface of the focusing ring 240 can be positioned at the same height as the top surface of the dielectric plate 220. The inner surface 240b of the top surface of the focusing ring 240 can support the edge region of the substrate S positioned outside the dielectric plate 220.

[0060] The outer portion 240a of the focusing ring 240 can be configured to surround the edge region of the substrate S. The focusing ring 240 can control the electromagnetic field to ensure a uniform plasma density distribution throughout the entire region of the substrate S. Therefore, the plasma is uniformly formed over the entire region of the substrate S, allowing each region of the substrate S to be uniformly etched. An edge impedance control circuit 600 can be connected to the focusing ring 240. The edge impedance control circuit 600 can control the impedance of the edge electrode 291 included in the focusing ring 240. The detailed configuration of the focusing ring 240 and the edge impedance control circuit 600 will be described below.

[0061] The bottom cover 250 may be located at the bottom end of the substrate support assembly 200. The bottom cover 250 may be positioned upwardly spaced from the bottom surface of the chamber 100. The bottom cover 250 may have a space having an open top surface formed therein.

[0062] The outer radius of the bottom cover 250 can have the same length as the outer radius of the main body 230. Within the interior space of the bottom cover 250, a lifting pin module (not shown) for moving the returned substrate S from the external transfer member to the electrostatic chuck can be positioned. This lifting pin module (not shown) can be spaced apart from the bottom cover 250 by a predetermined distance. The bottom surface of the bottom cover 250 can be made of a metallic material. Air can be provided within the interior space of the bottom cover 250. Since air has a dielectric constant lower than that of an insulator, it can be used to reduce the electromagnetic field inside the substrate support assembly 200.

[0063] The bottom cover 250 may have connecting members 253. The connecting members 253 connect the outer surface of the bottom cover 250 to the inner wall of the chamber 100. Multiple connecting members 253 may be disposed on the outer surface of the bottom cover 250 at fixed intervals. The connecting members 253 may support the substrate support assembly 200 inside the chamber 100. Furthermore, the connecting members 253 may be connected to the inner wall of the chamber 100, thereby electrically grounding the bottom cover 250. A first power line 223c connected to the first power supply 223a, a second power line 225c connected to the second power supply 225a, power lines 236c, 237c, and 238c connected to the three bottom power supplies 236a, 237a, and 238a, and a heat transfer medium supply line 231b connected to the heat transfer medium storage unit 231a, etc., may extend within the bottom cover 250 through the internal space of the connecting lines.

[0064] Plate 270 can be positioned between the electrostatic chuck and the bottom cover 250. Plate 270 can cover the top surface of the bottom cover 250. Plate 270 can be provided with a cross-sectional area corresponding to the body 230. Plate 270 may include an insulator. According to one embodiment, one or more plates 270 may be provided. Plate 270 can be used to increase the electrical distance between the body 230 and the bottom cover 250.

[0065] The plasma generation unit 300 can excite the process gas in the chamber 100 into a plasma state. The plasma generation unit 300 can use a capacitively coupled plasma (CCP) type plasma source. When using a CCP type plasma source, the chamber 100 can include a top electrode 330 and a bottom electrode, i.e., a body 230. The top electrode 330 and the bottom electrode 230 can be arranged parallel to each other in the up / down direction, having a processing space inserted therebetween. The top electrode 330 and the bottom electrode 230 can receive energy for plasma generation by receiving an radio frequency (RF) signal from a top power supply 310, and the number of RF signals applied to each electrode is not limited to the one shown. An electric field is formed in the space between the two electrodes, and the process gas supplied to this space can be excited in a plasma state. A substrate processing process is performed using this plasma.

[0066] Gas supply unit 400 supplies process gas to chamber 100. Gas supply unit 400 may include gas supply nozzle 410, gas supply line 420, and gas storage unit 430. Gas supply nozzle 410 may be mounted at the center of the top surface of chamber 100. Spray orifices may be formed on the bottom surface of gas supply nozzle 410. Injection port supplies process gas to chamber 100. Gas supply line 420 connects gas supply nozzle 410 and gas storage unit 430. Gas supply line 420 supplies process gas stored in gas storage unit 430 to gas supply nozzle 410. Valve 421 may be mounted on gas supply line 420. Valve 421 can open or close gas supply line 420 and control the flow rate of process gas supplied through gas supply line 420.

[0067] The partition unit 500 can be positioned between the inner wall of the chamber 100 and the substrate support assembly 200. The partition unit 500 can be arranged in an annular shape. Multiple through holes can be formed at the unit 500. The process gas supplied in the chamber 100 can pass through the through holes of the unit 500 and can be discharged through the discharge hole 102. The flow of the process gas can be controlled according to the shape of the unit 500 and the shape of its through holes.

[0068] Figure 2 This is a further enlarged block diagram of a substrate processing apparatus according to an embodiment of the present invention.

[0069] The support unit 200 according to the present invention may include a focusing ring 240 surrounding the substrate W and a coupling ring 290 disposed below the focusing ring 240. An insulator 281 and an insulator 282 may be included between the focusing ring 240 and the coupling ring 290. Figure 2 In one implementation, two insulators 281 and 282 may be provided, but they may be combined to form a single insulator.

[0070] Electrode 291 may be included in coupling ring 290. Edge impedance control circuitry 600 may be connected to electrode 291 included in coupling ring 290. Edge impedance control circuitry 600 and electrode 291 included in coupling ring 290 may be electrically connected to each other via RF cable 700. Edge impedance control circuitry 600 may provide an impedance path to ground for RF signals received in the edge region of substrate W. RF signals may flow to electrode 291 through the capacitance between focusing ring 240 and electrode 291. Electrode 291 may output RF signals.

[0071] The substrate processing apparatus according to the present invention may include: a top electrode 330 and a bottom electrode 230 arranged facing each other, the top electrode and the bottom electrode having a space in which plasma is generated in a process chamber 100; a top power supply 310 for applying power to the top electrode 330; and three bottom power supplies 236a, 237a and 238a for applying high-frequency power, each having a different frequency, to the bottom electrode 230.

[0072] The three bottom power supplies 236a, 237a and 238a are high-frequency power supplies that apply high-frequency power to the bottom electrode 230. Two of the high-frequency power supplies may have a frequency of 10 MHz or lower, and the other high-frequency power supply may have a frequency of 10 MHz or higher.

[0073] According to the present invention, the three high-frequency power supplies may include a first frequency power supply 236a and a second frequency power supply 237a having frequencies in the range of 50 kHz to 10 MHz, and a third frequency power supply 238c having frequencies in the range of 10 MHz to 100 MHz. In this case, the first frequency power supply 236a and the second frequency power supply 237a can control the ion energy incident on the substrate. A frequency of 10 MHz or less has high impedance in the vacuum chamber and is applied to a plasma sheath in which only ions are present, thereby increasing the ion energy to increase the etching rate by ions incident on the substrate. The third frequency power supply 238c can improve the plasma density. That is, when a high frequency of 10 MHz or higher is applied, the plasma sheath area is reduced, and therefore the ion energy is also reduced. Therefore, the power lost by ions is reduced, and thus the power applied from the third frequency power supply 238c having a frequency of 10 MHz or higher can be used to improve the plasma density.

[0074] In this invention, in order to obtain a high slope of the etching profile with a depth-to-width ratio, the first frequency power supply 236a and the second frequency power supply 237a can be adjusted to obtain a higher ion energy distribution.

[0075] In other words, in the present invention, the ion energy distribution can be adjusted by frequency adjustment of the first frequency power supply 236a and the second frequency power supply 237a and by control of the edge impedance control circuit 600.

[0076] refer to Figure 4 The diagram shows the cases where the first frequency power supply 236a has a frequency of 400kHz and 300kHz. According to... Figure 4 As can be seen from the exemplary embodiment, when the frequency of the first frequency power supply 236a is reduced from 400 kHz to 300 kHz, the ion energy increases by approximately 15%. That is, according to the present invention, the ion energy can be increased by adjusting the frequency of the first frequency power supply 236a to a lower value within a predetermined range. Furthermore, simulations have confirmed that using a lower frequency can include a higher IED.

[0077] The purpose of this invention is to control IED and HAR (high aspect ratio) etching. For HAR etching that does not have deflections such as bending, twisting or tilting, the purpose of this invention is to obtain higher IED and more uniform plasma.

[0078] In CCP plasma generation devices, harmonic generation produces static wave effects (SWEs) that alter plasma homogeneity. Because low and mid-frequency harmonics exhibit slight SWEs due to their larger wavelengths, these frequency changes have minimal impact on plasma homogeneity. However, at high frequencies, even small changes can amplify in the harmonics, potentially drastically altering both SWE and plasma homogeneity. In other words, locally inhomogeneous plasma can cause twisting or bending of the etching profile, leading to chip architecture failure.

[0079] Therefore, in this invention, without compromising plasma uniformity, a higher ion energy distribution can be obtained simply by controlling the frequencies of the first frequency power supply 236a and the second frequency power supply 237a, other than the highest frequency from the third frequency power supply 238a.

[0080] Referring to Figure 3, it is shown that the IED can be controlled by tuning the edge impedance control circuit 600. Figure 3A As can be seen, the ion energy density is concentrated at the edge. Furthermore, referencing... Figure 3B The diagram shows that the IED can be adjusted by tuning the edge impedance control circuit 600. Figure 3B The horizontal axis represents kinetic energy, and the vertical axis represents IED. It appears that kinetic energy and IED can be further adjusted by changing the tuning ratio of the variable capacitor or high-pass filter in the edge impedance control circuit 600 to 1%, 50%, and 100%, respectively.

[0081] Figure 5 This is a view showing the sloping profile of the 3D-NAND etching due to low ion energy.

[0082] As technology advances, semiconductor manufacturing structures become increasingly complex. The highest aspect ratio of traditional planar NAND architectures is approximately 15, but this represents an aspect ratio of 25 for first-generation NAND, while the aspect ratio for the latest 3D-NAND is approximately 100. At aspect ratios above 100, the etching profile shape exhibits stochastic action, making unforeseen consequences (such as twisting, bending, or tilting) almost unavoidable during etching. As the aspect ratio increases, the orientation and shape of the profile can be arbitrarily altered through polymer deposition and sidewall charge accumulation, weakening vertical etching stability. In 3D-NAND, the charge effect of the tungsten word line makes HAR etching more difficult, thereby disrupting the local electric field. When the electric field is disrupted, ions are randomly driven, leading to deflection and failure of the etching profile. More specifically, the stepped structure of 3D NAND architectures, including tungsten layers, disrupts the electric field. Such a stepped structure, in turn, alters the force balance and deflects ion orbitals. Figure 5 The diagram illustrates the bending of the etching profile due to charge effects. During etching, the bottom of the feature is filled with ions. When the etched feature contacts the tungsten line, the ions diffused along the tungsten conductive layer are essentially released. Therefore, “C” Repulsive force dominates "A" The force was thus applied, and the curvature of the "B" profile was observed. That is, the effect of ions tilting from the incomplete profile to the complete profile in HAR was amplified, and the etching profile was essentially tilted. Therefore, 3D-NAND production may fail when "B" contacts "A". To avoid... Figure 5 The tilting problem discussed earlier can be addressed by increasing the ion driving force along the vertical direction.

[0083] Therefore, for HAR, deflection solutions must precisely control high-energy ions during etching.

[0084] Figure 6 This is a view used to explain the formation of the total driving force of ions.

[0085] exist Figure 6 In this context, Fatr represents the horizontal force of gravity, Fkin represents the vertical force of ion kinetic energy, and Ft represents the total force acting on the ion.

[0086] refer to Figure 6 The tilt angle can be reduced by increasing the ion kinetic energy. This control of ion kinetic energy can be achieved by controlling the plasma sheath (increasing ion energy). Therefore, the present invention proposes a configuration for controlling the frequencies of the first frequency power supply 236a and the second frequency power supply 237a as a method for increasing the ion energy distribution with a high aspect ratio.

[0087] According to the present invention, it can be seen that changing the frequency from 400kHz to 300kHz increases the IED by approximately 15%. The increase in IED is due to the increase in CCP impedance at a lower frequency. A higher voltage drop across the CCP electrode at a fixed power corresponds to a higher load impedance, resulting in an increase in sheath voltage, which in turn leads to an increase in IED. Using the same concept, adjusting the intermediate frequency in the range of 9 to 10MHz achieves the effect of obtaining an even higher IED.

[0088] Furthermore, the edge impedance control circuit 600 can control the impedance of the edge electrode 291. In the case of a floating edge electrode, the equivalent area of ​​the bottom electrode is maximized due to the coupling between the electrostatic chuck and the edge electrode. When the impedance is low, the edge electrode potential approaches 0, allowing the equivalent area of ​​the bottom electrode to be reduced. Since the ratio of the top electrode to the bottom electrode is inversely proportional to the sheath voltage, this change can be tuned to the IED by the edge impedance control circuit 600.

[0089] Figures 7A to 7B A view showing an edge impedance control circuit 600 according to an embodiment of the present invention.

[0090] according to Figure 7A An edge impedance control circuit 600 according to an embodiment of the present invention may include one or more notch filters 610 and a variable capacitor 620 connected in series with the one or more notch filters 610.

[0091] refer to Figure 7B An edge impedance control circuit 600 according to an embodiment of the present invention may include one or more notch filters 610 and a high-pass filter 630 connected in series with the one or more notch filters 610.

[0092] refer to Figure 7A As shown in Figure B, the edge impedance control circuit 600 conceived according to the present invention may include one or more notch filters 610 to avoid impedance fluctuations at the first and second frequencies. Figure 7A and Figure 7B The implementation may include a first notch filter 611 for blocking a first frequency and a notch filter 612 for blocking a second frequency.

[0093] refer to Figure 7A The edge impedance control circuit 600 may include a variable capacitor 620 connected in series with the notch filter 610. The high-frequency impedance can be controlled by adjusting the capacitance of the variable capacitor 620.

[0094] refer to Figure 7BThe edge impedance control circuit 600 may include a high-pass filter 630 connected in series with the notch filter 610. The high-pass filter 630 may include a controllable cutoff frequency to classify higher harmonics and reduce inhomogeneities caused by quiescent effects. The high-pass filter 630 can control the shunting of high-frequency, higher harmonics.

[0095] In this invention, the impedance in the edge region at 60 MHz can be adjusted by tuning the high-frequency impedance. Furthermore, the plasma characteristics inside the chamber can be altered, the IED can be adjusted, and there is an effect where no change in IAD is observed.

[0096] According to the concept of the present invention, using according to Figure 1 The substrate processing apparatus can process substrates in a substrate processing apparatus that generates plasma inside a process chamber.

[0097] The inventive concept may include controlling the first frequency of the first frequency power supply and the second frequency of the second frequency power supply without controlling the third frequency of the third frequency power supply applied to the bottom electrode; and blocking the first frequency and the second frequency, and controlling the high-frequency impedance that occurs due to the third frequency.

[0098] In this case, the step of controlling the high-frequency impedance that occurs due to the third frequency is the step of tuning the edge impedance control circuit.

[0099] The first frequency can be controlled within the range of 100kHz to 400kHz, and the second frequency within the range of 2MHz to 10MHz. The first frequency can be reduced from a first value to a second value lower than the first value through control. This achieves the effect of maintaining a high aspect ratio and increasing ion energy distribution.

[0100] While preferred embodiments of the inventive concept have been described and illustrated so far, the inventive concept is not limited to the specific embodiments described above, and it is worth noting that those skilled in the art who fall within the scope of the inventive concept can implement the inventive concept in different ways without departing from the essence of the inventive concept claimed in the claims, and modifications should not be interpreted separately from the technical spirit or prospect of the inventive concept.

Claims

1. A substrate processing apparatus, the substrate processing apparatus comprising: A process chamber having processing space; A support unit for supporting a substrate in the process chamber; A gas supply unit, the gas supply unit being used to supply process gas into the process chamber; as well as A plasma generation unit is used to generate plasma from the process gas. The plasma generation unit includes: A top electrode, wherein the top electrode is disposed above the substrate; A bottom electrode is disposed below the substrate; An edge electrode is disposed at the edge surrounding the substrate; Three high-frequency power supplies, which apply high-frequency power to the bottom electrode, include: a first frequency power supply having a range between 100 kHz and 400 kHz; a second frequency power supply having a range between 2 MHz and 10 MHz; and a third frequency power supply having a range of 60 MHz or higher; and An edge impedance control circuit is connected to the edge electrode and includes one or more notch filters and a variable capacitor connected in series with the one or more notch filters.

2. The substrate processing apparatus according to claim 1, wherein, The one or more notch filters block frequencies within the range of the first and second frequency power supplies, and the variable capacitor controls the impedance of the third frequency power supply.

3. A substrate processing apparatus, the substrate processing apparatus comprising: A process chamber having processing space; A support unit for supporting a substrate in the process chamber; A gas supply unit, the gas supply unit being used to supply process gas into the process chamber; as well as A plasma generation unit is used to generate plasma from the process gas. The plasma generation unit includes: A top electrode, wherein the top electrode is disposed above the substrate; A bottom electrode is disposed below the substrate; An edge electrode is disposed at the edge surrounding the substrate; Three high-frequency power supplies, which apply high-frequency power to the bottom electrode, include: a first frequency power supply having a range between 100 kHz and 400 kHz; a second frequency power supply having a range between 2 MHz and 10 MHz; and a third frequency power supply having a range of 60 MHz or higher; and An edge impedance control circuit is connected to the edge electrode and includes one or more notch filters and a high-pass filter, the high-pass filter being connected in series with the one or more notch filters.

4. The substrate processing apparatus according to claim 3, wherein, The one or more notch filters block frequencies within the range of the first and second frequency power supplies, and the high-pass filter controls the impedance of the third frequency power supply and shunts the harmonics of the third frequency power supply.

5. A substrate processing apparatus, the substrate processing apparatus comprising: A process chamber having processing space; A support unit for supporting a substrate in the process chamber; A gas supply unit, the gas supply unit being used to supply process gas into the process chamber; as well as A plasma generation unit is used to generate plasma from the process gas. The plasma generation unit includes: A top electrode, wherein the top electrode is disposed above the substrate; Bottom electrode, the bottom electrode being disposed below the substrate; and Three high-frequency power supplies, which apply high-frequency power to the bottom electrode, include: a first frequency power supply having a range between 100 kHz and 400 kHz; a second frequency power supply having a range between 2 MHz and 10 MHz; and a third frequency power supply having a range of 60 MHz or higher; and The support unit includes: An edge ring surrounds the substrate; A coupling ring, disposed below the edge ring, and including an edge electrode within the coupling ring; and An edge impedance control circuit is connected to the edge electrode and includes one or more notch filters and a variable capacitor connected in series with the one or more notch filters.

6. The substrate processing apparatus according to claim 5, wherein, The one or more notch filters block frequencies within the range of the first and second frequency power supplies, and the variable capacitor controls the impedance of the third frequency power supply.

7. A substrate processing apparatus, the substrate processing apparatus comprising: A process chamber having processing space; A support unit for supporting a substrate in the process chamber; A gas supply unit, the gas supply unit being used to supply process gas into the process chamber; as well as A plasma generation unit is used to generate plasma from the process gas. The plasma generation unit includes: A top electrode, wherein the top electrode is disposed above the substrate; Bottom electrode, the bottom electrode being disposed below the substrate; and Three high-frequency power supplies, which apply high-frequency power to the bottom electrode, include: a first frequency power supply having a range between 100 kHz and 400 kHz; a second frequency power supply having a range between 2 MHz and 10 MHz; and a third frequency power supply having a range of 60 MHz or higher; and The support unit includes: An edge ring surrounds the substrate; A coupling ring, disposed below the edge ring, and including an edge electrode within the coupling ring; and An edge impedance control circuit is connected to the edge electrode and includes one or more notch filters and a high-pass filter, the high-pass filter being connected in series with the one or more notch filters.

8. The substrate processing apparatus according to claim 7, wherein, The one or more notch filters block frequencies within the range of the first and second frequency power supplies, and the high-pass filter controls the impedance of the third frequency power supply and shunts the harmonics of the third frequency power supply.

9. A substrate processing method, wherein the substrate processing method uses a substrate processing apparatus according to any one of claims 1 to 8 to generate plasma in a process chamber, the substrate processing method comprising: Without controlling the third frequency of the third frequency power supply applied to the bottom electrode, control the first frequency of the first frequency power supply and the second frequency of the second frequency power supply; as well as Block the first frequency and the second frequency and control the high-frequency impedance of the third frequency.

10. The substrate processing method according to claim 9, wherein, The high-frequency impedance that controls the third frequency includes tuning the edge impedance control circuit.

11. The substrate processing method according to claim 10, wherein, The first frequency is reduced from a first value to a second value lower than the first value by the control.

Images