Etching method and plasma treatment device

Abstract

The etching method disclosed in this invention includes: (a) a step of etching a titanium nitride film using a first plasma; and (b) a step of etching a titanium nitride film using a second plasma. The first plasma is generated by a first process gas, and the second plasma is generated by a second process gas. One of the first and second process gases contains a chlorine-containing gas and a fluorocarbon gas, and the other contains a chlorine-containing gas but does not contain a fluorocarbon gas. The cycle comprising (a) and (b) is repeated. The repetition of the cycle is stopped when the titanium nitride film is partially etched in its thickness direction.

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to an etching method and a plasma treatment apparatus. Background Technology

[0002] Japanese Patent Application Publication No. 2004-519838 (hereinafter referred to as "Patent Document 1") discloses a plasma etching method for processing films on substrates. Specifically, Patent Document 1 discloses that in the plasma etching of titanium nitride films, plasma generated from a gas containing chlorine and fluorocarbon is used. Summary of the Invention

[0003] The present invention provides the following technology: suppressing the roughness of the bottom surface obtained by local etching of titanium nitride film, and reducing the difference in etching rate of titanium nitride film caused by pattern density.

[0004] In one exemplary embodiment, an etching method is provided. The etching method includes: (a) a step of etching a titanium nitride film using a first plasma. The etching method further includes: (b) a step of etching the titanium nitride film using a second plasma. The first plasma is generated by a first process gas, and the second plasma is generated by a second process gas. One of the first and second process gases contains a chlorine-containing gas and a fluorocarbon gas. The other of the first and second process gases contains a chlorine-containing gas and does not contain a fluorocarbon gas. In the etching method, the cycle including (a) and (b) is repeatedly performed. The repetition of the cycle is stopped when the titanium nitride film is partially etched in its thickness direction, so that the titanium nitride film provides a bottom surface between its upper and lower surfaces.

[0005] According to one exemplary embodiment, the roughness of the bottom surface obtained by local etching of the titanium nitride film can be suppressed, and the difference in etching rate of the titanium nitride film caused by the density of the pattern can be reduced. Attached Figure Description

[0006] Figure 1 This is a flowchart of an etching method according to an exemplary implementation.

[0007] Figure 2 This is a partially enlarged cross-sectional view of a substrate as an example.

[0008] Figure 3 (a)~ Figure 3 (c) are respectively in Figure 1 A partially enlarged cross-sectional view of the substrate produced in the corresponding process of the etching method shown.

[0009] Figure 4 This is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment. Detailed Implementation

[0010] The following describes various exemplary embodiments.

[0011] In one exemplary embodiment, an etching method is provided. The etching method includes: (a) a step of etching a titanium nitride film using a first plasma. The etching method further includes: (b) a step of etching the titanium nitride film using a second plasma. The first plasma is generated by a first process gas, and the second plasma is generated by a second process gas. One of the first and second process gases contains a chlorine-containing gas and a fluorocarbon gas. The other of the first and second process gases contains a chlorine-containing gas and does not contain a fluorocarbon gas. In the etching method, the cycle including (a) and (b) is repeatedly performed. The repetition of the cycle is stopped when the titanium nitride film is partially etched in its thickness direction, so that the titanium nitride film provides a bottom surface between its upper and lower surfaces.

[0012] In etching based on plasma generated by a process gas containing chlorine gas but not fluorocarbon gas, the difference in etching rate of the titanium nitride film resulting from the pattern density is small. However, in etching based on plasma generated by a process gas containing chlorine gas but not fluorocarbon gas, the roughness of the bottom surface obtained by local etching of the titanium nitride film increases. On the other hand, in etching based on plasma generated by a process gas containing both chlorine gas and fluorocarbon gas, the roughness of the bottom surface obtained by local etching of the titanium nitride film is suppressed. However, in etching based on plasma generated by a process gas containing both chlorine gas and fluorocarbon gas, the difference in etching rate of the titanium nitride film resulting from the pattern density increases. In the above embodiment, plasma etching of the titanium nitride film based on a first plasma generated by a first process gas and plasma etching of the titanium nitride film based on a second plasma generated by a second process gas are performed alternately. Therefore, according to the above embodiment, the roughness of the bottom surface obtained by local etching of the titanium nitride film can be suppressed, and the difference in etching rate of the titanium nitride film resulting from the pattern density can be reduced.

[0013] In one exemplary embodiment, the substrate having a titanium nitride film may further have a phase change material layer. The titanium nitride film is disposed on the phase change material layer. In this embodiment, the etching method may further include a step of etching a portion of the titanium nitride film between the bottom surface and the lower surface, and a portion of the phase change material layer in the thickness direction, using a third plasma generated by a third process gas.

[0014] In one exemplary embodiment, the third processing gas may contain a bromine-containing gas. According to this embodiment, the phase change material layer can be etched while suppressing damage to the phase change material layer.

[0015] In one exemplary embodiment, the phase change material layer may be formed of germanium, antimony, and tellurium.

[0016] In one exemplary embodiment, the etching method may further include a step of further etching the phase change material layer using a fourth plasma generated by a fourth process gas.

[0017] In one exemplary embodiment, the fourth processing gas may contain hydrogen and hydrocarbon gas.

[0018] In one exemplary embodiment, the time lengths of (a) and (b) in the cycle can be more than 1 second and less than 3 seconds, respectively. According to this embodiment, the roughness of the bottom surface obtained by local etching of the titanium nitride film can be suppressed more effectively, and the difference in etching rate of the titanium nitride film caused by the density of the pattern can be reduced more effectively.

[0019] In another exemplary embodiment, a plasma processing apparatus may be provided. The plasma processing apparatus includes a chamber, a substrate support, a gas supply unit, a plasma generation unit, and a control unit. The substrate support is configured to support a substrate within the chamber. The gas supply unit is configured to supply a first processing gas and a second processing gas within the chamber. The plasma generation unit is configured to generate plasma from the gas within the chamber. The control unit is configured to control the gas supply unit and the plasma generation unit. One of the first and second processing gases contains a chlorine-containing gas and a fluorocarbon gas. The other of the first and second processing gases contains a chlorine-containing gas and does not contain a fluorocarbon gas. The control unit repeatedly executes a control cycle including the first control and the second control. The first control executed by the control unit includes controlling the gas supply unit and the plasma generation unit to generate a first plasma from the first processing gas within the chamber to etch a titanium nitride film on the substrate supported by the substrate support. The second control executed by the control unit includes controlling the gas supply unit and the plasma generation unit to generate a second plasma from the second processing gas within the chamber to etch a titanium nitride film. Regarding the repeated control of the cycle, it is stopped when the titanium nitride film is partially etched in its thickness direction, so that the titanium nitride film provides a bottom surface between its upper and lower surfaces.

[0020] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent parts are labeled with the same symbols.

[0021] Figure 1 This is a flowchart of an etching method according to an exemplary implementation. Figure 1 The etching method shown (hereinafter referred to as "Method MT") is performed to etch a titanium nitride film on a substrate.

[0022] Figure 2 This is a partially enlarged cross-sectional view of a substrate as an example. The MT method is applicable to... Figure 2 The substrate W shown has a titanium nitride film TNF. The substrate W may also have a PCL layer. The PCL layer is a phase change material layer. The titanium nitride film TNF is disposed on the PCL layer. The substrate W including the PCL layer is used, for example, to manufacture a phase change memory. The PCL layer is formed of a chalcogenide alloy. The PCL layer may contain germanium (Ge), antimony (Sb), and tellurium (Te). The composition of the PCL layer is, for example, Ge2Sb2Te5.

[0023] The substrate W may also have a mask MK. The mask MK is disposed on a titanium nitride film TNF. The mask MK has a pattern transferred onto the titanium nitride film TNF. That is, the mask MK is patterned to provide patterns and spaces. The mask MK has regions providing wider spaces, i.e., regions in which patterns are disposed at a relatively low density (hereinafter referred to as "coarse regions"). And, the mask MK has regions providing narrower spaces, i.e., regions in which patterns are disposed at a relatively high density (hereinafter referred to as "dense regions").

[0024] The mask MK is formed of a material having an etching rate lower than that of the titanium nitride film TNF in processes ST1 and ST2, as described later. The mask MK is, for example, formed of silicon nitride.

[0025] The substrate W may also have a base region UR. A layer PCL is disposed on the base region UR. The base region UR is formed, for example, from silicon nitride.

[0026] The following, with Figure 1 and Figure 2 Together, for reference Figure 3 (a)~ Figure 3 (c) Figure 3 (a)~ Figure 3 (c) are respectively in Figure 1 A partially enlarged cross-sectional view of the substrate produced in the corresponding process of the etching method shown.

[0027] like Figure 1 As shown, method MT includes steps ST1 and ST2. Steps ST1 and ST2 are arranged within the chamber of the plasma processing apparatus. Figure 2 The process is performed in the state of the substrate W shown. In step ST1, the titanium nitride film TNF is etched using a first plasma generated in the chamber. In the following step ST2, the titanium nitride film TNF is etched using a second plasma generated in the chamber of the plasma processing apparatus. In steps ST1 and ST2, the portion of the titanium nitride film TNF exposed from the mask MK is etched.

[0028] In step ST1, the first plasma is generated by the first processing gas, and in step ST2, the second plasma is generated by the second processing gas. One of the first and second processing gases contains both a chlorine-containing gas and a fluorocarbon gas. The other of the first and second processing gases contains a chlorine-containing gas but does not contain a fluorocarbon gas. The chlorine-containing gas includes, for example, one or more of Cl2, HCl, CH3Cl, and ClF. The fluorocarbon gas is, for example, CF4 gas.

[0029] In method MT, the cycle CY, which includes operations ST1 and ST2, is executed repeatedly. Regarding the repetition of cycle CY, as follows... Figure 3 As shown in (a), the process is stopped when the titanium nitride film TNF is locally etched in its thickness direction. As a result of repeated cycles of CY, the titanium nitride film TNF provides a bottom surface BS. The bottom surface BS is provided between the upper surface US and the lower surface LS of the titanium nitride film TNF.

[0030] Method MT may include step STJ. In step STJ, it is determined whether a stopping condition is met. For example, in step STJ, the stopping condition is determined to be met if the number of repetitions of cycle CY reaches a predetermined number. If the number of repetitions of cycle CY reaches the predetermined number, the etching of the titanium nitride film TNF proceeds as follows: Figure 3 The process stops when the titanium nitride film TNF is partially etched along its thickness direction, as shown in (a). If the stopping condition is not met in process STJ, cycle CY is executed again. If the stopping condition is met in process STJ, the repetition of cycle CY ends.

[0031] In etching based on plasma generated by a process gas containing chlorine gas but not fluorocarbon gas, the difference in etching rate of the titanium nitride film resulting from the pattern density is small. However, in etching based on plasma generated by a process gas containing chlorine gas but not fluorocarbon gas, the roughness of the bottom surface obtained by local etching of the titanium nitride film increases.

[0032] On the other hand, in etching based on plasma generated by a process gas containing chlorine and fluorocarbon gases, the roughness of the bottom surface obtained by local etching of the titanium nitride film is suppressed. However, in etching based on plasma generated by a process gas containing chlorine and fluorocarbon gases, the difference in etching rate of the titanium nitride film caused by the pattern density becomes larger. Specifically, in etching based on plasma generated by a process gas containing chlorine and fluorocarbon gases, the etching rate of the titanium nitride film in the coarse region is low, while the etching rate of the titanium nitride film in the dense region is high.

[0033] In method MT, plasma etching of the titanium nitride film TNF based on a first plasma generated by a first process gas and plasma etching of the titanium nitride film TNF based on a second plasma generated by a second process gas are performed alternately. Therefore, according to method MT, the roughness of the bottom surface BS obtained by local etching of the titanium nitride film TNF can be suppressed, and the difference in etching rate of the titanium nitride film TNF caused by the pattern density can be reduced.

[0034] In one embodiment, the time lengths of process ST1 and process ST2 in cycle CY can be more than 1 second and less than 3 seconds, respectively. According to this embodiment, the roughness of the bottom surface BS obtained by local etching of the titanium nitride film TNF can be more effectively suppressed, and the difference in etching rate of the titanium nitride film TNF caused by the pattern density can be more effectively reduced.

[0035] In one embodiment, method MT may further include step ST3. Step ST3 is performed after repeated execution of cycle CY. Step ST3 is disposed within the chamber of the plasma processing apparatus. Figure 3 The process is performed in the state of the substrate W shown in (a). When performing step ST3, a plasma processing apparatus for repeatedly performing cycle CY can be used. That is, cycle CY and step ST3 can be performed using a single plasma processing apparatus. Alternatively, step ST3 can be performed using a plasma processing apparatus different from the plasma processing apparatus for repeatedly performing cycle CY. When step ST3 is performed using a plasma processing apparatus different from the plasma processing apparatus for repeatedly performing cycle CY, the substrate W can be transported between these plasma processing apparatuses via a depressurized environment. That is, the substrate W can be transported between these plasma processing apparatuses without breaking the vacuum.

[0036] In process ST3, a third plasma generated within the plasma processing chamber is used to etch the portion between the bottom surface BS and the lower surface LS of the titanium nitride film TNF, as well as a portion of the PCL layer in the thickness direction. Figure 3 Example of the state of substrate W after performing process ST3 is shown in (b).

[0037] In process ST3, a third plasma is generated by a third process gas. Regarding the third process gas, it can be selected in a manner that minimizes the damage to the PCL layer caused by the third plasma compared to the damage that might occur simply by repeatedly etching the PCL layer using cyclic CY. The third process gas may contain a halogen gas. The third process gas may contain other gases that dilute the halogen gas (e.g., inactive gases such as rare gases). Alternatively, the third process gas may contain a halogen gas and C. x Hy X z A mixture of gases. Here, "X" represents a halogen element, and x, y, and z are integers greater than or equal to 0. A halogen gas is, for example, Cl₂ gas. C x H y X z The gas used is, for example, hydrogen bromide (HBr gas), CH3F gas, CHF3 gas, or CF4 gas. According to process ST3, the PCL layer can be etched while suppressing damage to the PCL layer.

[0038] In one embodiment, method MT may further include step ST4. Step ST4 is performed after step ST3. Step ST4 is disposed within the chamber of the plasma processing apparatus. Figure 3 The process is performed in the state of substrate W shown in (b). When performing step ST4, a plasma processing apparatus for repeatedly performing cycle CY or the plasma processing apparatus used in step ST3 can be used. Cycle CY, step ST3, and step ST4 can be performed using a single plasma processing apparatus. Alternatively, step ST4 can be performed using a plasma processing apparatus for repeatedly performing cycle CY and a plasma processing apparatus different from the one used in step ST3. When step ST4 is performed using a plasma processing apparatus different from the one used in step ST3, substrate W can be transported between these plasma processing apparatuses in a depressurized environment. That is, substrate W can be transported between these plasma processing apparatuses without breaking the vacuum.

[0039] In process ST4, a fourth plasma generated within the chamber of the plasma processing apparatus is used to further etch the PCL layer. For example... Figure 3 As shown in (c), the PCL layer can be etched in process ST4 to expose the substrate region UR.

[0040] In step ST4, the fourth plasma is generated by the fourth processing gas. The fourth processing gas may contain hydrogen (H2 gas), a mixture of hydrogen and hydrocarbon gases (e.g., methane gas), hydrogen halides (e.g., HBr gas), or one or more organic halide gases. The fourth processing gas may be a mixture of hydrogen, hydrocarbon gases, hydrogen halides, and one or more organic halide gases. The one or more organic halide gases may contain one or more of CH3F gas, CHF3 gas, and CF4 gas.

[0041] The plasma processing apparatus that can be used to perform method MT will be described below. Figure 4 This is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment.

[0042] Figure 4 The plasma processing apparatus 1 shown is an inductively coupled plasma processing apparatus. The plasma processing apparatus 1 includes a chamber 10. A space Sp is provided within the chamber 10. Plasma processing of the substrate W is performed in the space Sp. In one embodiment, the chamber 10 may include a chamber body 12. The chamber body 12 has a generally cylindrical shape (e.g., a generally circular shape). The chamber body 12 is formed of a metal such as aluminum. A space Sp is provided inside the chamber body 12.

[0043] The plasma processing apparatus 1 also includes a substrate support 16. The substrate support 16 is configured to support the substrate W within the chamber 10. The substrate support 16 can be supported by a support portion 14. The support portion 14 is disposed on the bottom of the chamber 10. The support portion 14 may have a generally cylindrical shape. The support portion 14 may be formed of an insulating material. The insulating material of the support portion 14 may be quartz. The support portion 14 extends upward from the bottom of the chamber 10 within the chamber 10.

[0044] In one embodiment, the substrate support 16 may include a lower electrode 18 and an electrostatic chuck 20. The substrate support 16 may also include an electrode plate 19. The electrode plate 19 is formed of a metal such as aluminum. The electrode plate 19 has a generally disk-shaped form.

[0045] A lower electrode 18 is disposed on an electrode plate 19. The lower electrode 18 is formed of a metal such as aluminum. The lower electrode 18 has a generally disc-shaped shape. The lower electrode 18 is electrically connected to the electrode plate 19. A flow path 24 can be provided in the lower electrode 18. The flow path 24 constitutes a temperature regulating mechanism. The flow path 24 is connected to a cooling unit disposed outside the chamber 10 via pipes 26a and 26b. The cooling unit supplies refrigerant to the flow path 24 via pipe 26a. The refrigerant supplied to the flow path 24 returns to the cooling unit via pipe 26b. The temperature of the substrate W supported by the substrate support 16 is controlled by controlling the temperature of the refrigerant supplied to the flow path 24.

[0046] An electrostatic chuck 20 is disposed on the lower electrode 18. A substrate W is placed on the electrostatic chuck 20. The electrostatic chuck 20 includes a body and electrodes. The body of the electrostatic chuck 20 is formed of a dielectric such as aluminum oxide or aluminum nitride. The electrodes of the electrostatic chuck 20 are conductive films and are disposed in the body of the electrostatic chuck 20. A DC power supply 22 is connected to the electrodes of the electrostatic chuck 20 via a switch 23. When a DC voltage from the DC power supply 22 is applied to the electrodes of the electrostatic chuck 20, an electrostatic attraction is generated between the substrate W placed on the electrostatic chuck 20 and the electrostatic chuck 20. Due to the generated electrostatic attraction, the substrate W is held by the electrostatic chuck 20.

[0047] The substrate support 16 can further support the edge ring ER mounted thereon. The edge ring ER is generally annular. The edge ring ER is formed, for example, from silicon, silicon carbide, or quartz. The substrate W is disposed on the electrostatic chuck 20 and within the area surrounded by the edge ring ER.

[0048] In one embodiment, the plasma processing apparatus 1 may further include a gas supply line 28. The gas supply line 28 supplies heat transfer gas (e.g., He gas) from the heat transfer gas supply mechanism to the gap between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0049] In one embodiment, the plasma processing apparatus 1 may further include a heater HT. The heater HT may be disposed in the substrate support 16 to regulate the temperature of the substrate W. The heater HT may be disposed in the electrostatic chuck 20. A heater power supply HP is connected to the heater HT. When power is supplied to the heater HT from the heater power supply HP, the heater HT heats up, thereby regulating the temperature of the substrate W.

[0050] In one embodiment, the plasma processing apparatus 1 may further include a dielectric 194. The dielectric 194 may be plate-shaped. The dielectric 194 is disposed above the substrate support 16. The dielectric 194 constitutes a canopy portion that divides the space Sp.

[0051] In one embodiment, the plasma processing apparatus 1 may further include a shield 46. The shield 46 can be detachably mounted along the inner wall of the chamber 10. The shield 46 may also be disposed on the outer periphery of the support portion 14. The shield 46 prevents etching byproducts from adhering to the chamber 10. The shield 46 may be formed, for example, by coating the surface of an aluminum component with a ceramic such as Y2O3.

[0052] In one embodiment, the plasma processing apparatus 1 may further include a baffle member 48. The baffle member 48 is disposed between the support portion 14 and the side wall of the chamber 10. The baffle member 48 can be formed, for example, by coating the surface of a plate-shaped component made of aluminum with a ceramic such as Y2O3. A plurality of through holes are formed in the baffle member 48.

[0053] In one embodiment, an exhaust port 12e may be provided at the bottom of chamber 10. The plasma processing apparatus 1 may also include an exhaust device 50. The exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 may include a vacuum pump such as a turbomolecular pump and a pressure controller (e.g., an automatic pressure control valve). The exhaust device 50 is capable of reducing the pressure of space Sp to a specified pressure.

[0054] In one embodiment, the plasma processing apparatus 1 may further include a high-frequency power supply 64. The high-frequency power supply 64 is a power supply that generates high-frequency power, i.e., high-frequency bias power, for introducing ions into the substrate W. The frequency of the high-frequency bias power is, for example, 400 kHz or higher and 40.68 MHz or lower. The high-frequency power supply 64 is electrically connected to the lower electrode 18 via a matching device 68. The matching device 68 has circuitry for matching the impedance of the load side (lower electrode 18 side) of the high-frequency power supply 64 with the output impedance of the high-frequency power supply 64.

[0055] The plasma processing apparatus 1 may also include a gas supply unit 120. The gas supply unit 120 is configured to supply the first and second processing gases to the space Sp. The gas supply unit 120 may also be configured to supply a third and / or a fourth processing gas to the space Sp, in addition to the first and second processing gases. A gas inlet 121 may be provided on the side wall of the chamber 10. The gas supply unit 120 may be connected to the gas inlet 121 via a pipe 123.

[0056] The gas supply unit 120 may include a gas supply source 122, a flow controller 124, and an on / off valve 126. The gas supply source 122 includes a first processed gas source and a second processed gas source. The gas supply source 122 may also include a third processed gas source and / or a fourth processed gas source. The gas supply source 122 is connected to the space Sp via the flow controller 124 and the on / off valve 126. The gas supply source 122 may be connected to the piping 123 via the flow controller 124 and the on / off valve 126. The flow controller 124 is, for example, a mass flow controller or a pressure-controlled flow controller. Gas from the gas supply source 122 is supplied to the space Sp with its flow rate regulated by the flow controller 124.

[0057] Furthermore, the structure of the gas supply unit 120 is not limited to... Figure 4 The structure shown is illustrated. In another embodiment, the gas supply unit 120 may be configured to supply gas from the ceiling portion of the chamber 10 to the space Sp. The gas supply unit 120 may supply gas to the space Sp from a gas inlet formed, for example, in the central portion of the dielectric 194.

[0058] The plasma processing apparatus 1 further includes a plasma generation unit. The plasma generation unit is configured to generate plasma from gas within the chamber 10. The plasma generation unit introduces energy that excites the gas within the chamber 10 into the chamber 10. In one embodiment, the plasma generation unit may include an antenna 140. The antenna 140 is a planar high-frequency antenna and is disposed above the dielectric 194. The antenna 140 may be covered by a shielding member 160.

[0059] In one embodiment, antenna 140 may include an inner antenna element 142A and an outer antenna element 142B. The inner antenna element 142A is disposed above the central portion of dielectric 194. The outer antenna element 142B is configured to surround the outer periphery of the inner antenna element 142A. The inner antenna element 142A and the outer antenna element 142B are respectively formed of a conductor such as copper, aluminum, or stainless steel. The inner antenna element 142A and the outer antenna element 142B may each be formed in a helical shape.

[0060] The inner antenna element 142A and the outer antenna element 142B can be fixed together by a plurality of clamping bodies 144. Each of the plurality of clamping bodies 144 is, for example, rod-shaped. The plurality of clamping bodies 144 are arranged radially, extending from near the center of the inner antenna element 142A to the outside of the outer antenna element 142B.

[0061] The shielding component 160 may include an inner shielding wall 162A and an outer shielding wall 162B. The inner shielding wall 162A is disposed between the inner antenna element 142A and the outer antenna element 142B in a manner that surrounds the inner antenna element 142A. The outer shielding wall 162B is disposed to surround the outer antenna element 142B. The outer shielding wall 162B may have a cylindrical shape. In this example, the space above the dielectric 194 is divided into an inner central region of the inner shielding wall 162A and a peripheral region between the inner shielding wall 162A and the outer shielding wall 162B.

[0062] The shielding component 160 may further include an inner shielding plate 164A and an outer shielding plate 164B. The inner shielding plate 164A may have a circular plate shape. The inner shielding plate 164A is disposed above the inner antenna element 142A to close the opening of the inner shielding wall 162A. The outer shielding plate 164B may have a generally annular plate shape. The outer shielding plate 164B is disposed above the outer antenna element 142B to close the opening between the inner shielding wall 162A and the outer shielding wall 162B.

[0063] High-frequency power supplies 150A and 150B are connected to the inner antenna element 142A and the outer antenna element 142B, respectively. The high-frequency power supplies 150A and 150B supply high-frequency power of the same or different frequencies to the inner antenna element 142A and the outer antenna element 142B, respectively. For example, the frequency of the high-frequency power supplied by the high-frequency power supplies 150A and 150B is 27MHz. If high-frequency power from the high-frequency power supply 150A is supplied to the inner antenna element 142A, the inner antenna element 142A generates an induced magnetic field within the cavity 10. The generated induced magnetic field excites the gas within the cavity 10, generating a ring-shaped plasma above the center of the substrate W. If high-frequency power from the high-frequency power supply 150B is supplied to the outer antenna element 142B, the outer antenna element 142B generates an induced magnetic field within the cavity 10. The generated induced magnetic field excites the gas within the cavity 10, generating a ring-shaped plasma above the periphery of the substrate W.

[0064] In another embodiment, the plasma processing apparatus 1 may further include actuators 168A and 168B. Actuators 168A and 168B are used to adjust the electrical length of the inner antenna element 142A and the outer antenna element 142B respectively, based on the high-frequency power output from the high-frequency power supplies 150A and 150B. Actuators 168A and 168B adjust the electrical length of the inner antenna element 142A and the outer antenna element 142B respectively by adjusting the height-direction position of the inner shielding plate 164A and the height-direction position of the outer shielding plate 164B.

[0065] The plasma processing apparatus 1 may also include a control unit 80. The control unit 80 is configured to control each component of the plasma processing apparatus 1. The control unit 80 may be a computer equipped with a processor, storage device, input device, display device, etc. The control unit 80 executes a control program stored in the storage device and controls each component of the plasma processing apparatus 1 according to the scheme data stored in the storage device. The method MT can be executed in the plasma processing apparatus 1 through the control of each component of the plasma processing apparatus 1 based on the control unit 80.

[0066] The control unit 80 repeatedly executes a control cycle including a first control and a second control. The first control executed by the control unit 80 includes controlling the gas supply unit 120 and the plasma generation unit to generate a first plasma from a first processing gas within the chamber 10 to etch the titanium nitride film TNF on the substrate W supported by the substrate support 16. In one embodiment, the first control includes controlling the gas supply unit 120 to supply the first processing gas into the chamber 10. The first control may also include controlling the exhaust device 50 to set the pressure within the chamber 10 to a specified pressure. The first control further includes controlling the plasma generation unit to generate plasma from the first processing gas within the chamber 10. In the first control, the control unit 80 controls the high-frequency power supply 150A and the high-frequency power supply 150B respectively to supply high-frequency power to the inner antenna element 142A and the outer antenna element 142B. The first control may also include controlling the high-frequency power supply 64 to supply high-frequency bias power to the lower electrode 18. Process ST1 is executed by the first control based on the control unit 80.

[0067] The second control performed by the control unit 80 includes controlling the gas supply unit 120 and the plasma generation unit to generate a second plasma from the second processing gas within the chamber 10 to etch the titanium nitride film TNF on the substrate W supported by the substrate support 16. In one embodiment, the second control includes controlling the gas supply unit 120 to supply the second processing gas into the chamber 10. The second control may also include controlling the exhaust device 50 to set the pressure within the chamber 10 to a specified pressure. The second control further includes controlling the plasma generation unit to generate plasma from the second processing gas within the chamber 10. In the second control, the control unit 80 controls the high-frequency power supply 150A and the high-frequency power supply 150B to supply high-frequency power to the inner antenna element 142A and the outer antenna element 142B, respectively. The second control may also include controlling the high-frequency power supply 64 to supply high-frequency bias power to the lower electrode 18. Process ST2 is executed based on the second control of the control unit 80.

[0068] The control unit 80 stops the repetition of the control cycle to halt the etching of the titanium nitride film TNF while it is partially etched in its thickness direction. At the end of the control cycle, a bottom surface BS is provided between the upper surface US and the lower surface LS of the titanium nitride film TNF.

[0069] In one embodiment, the control unit 80 may also perform a third control. The third control is performed after repeatedly executing the above control cycle. The third control includes controlling the gas supply unit 120 and the plasma generation unit to generate a third plasma from the third processing gas within the chamber 10 to etch a portion of the titanium nitride film TNF and the PCL layer of the substrate W supported by the substrate support 16. In one embodiment, the third control includes controlling the gas supply unit 120 to supply the third processing gas into the chamber 10. The third control may also include controlling the exhaust device 50 to set the pressure within the chamber 10 to a specified pressure. The third control further includes controlling the plasma generation unit to generate plasma from the third processing gas within the chamber 10. In the third control, the control unit 80 controls the high-frequency power supply 150A and the high-frequency power supply 150B respectively to supply high-frequency power to the inner antenna element 142A and the outer antenna element 142B. The third control may also include controlling the high-frequency power supply 64 to supply high-frequency bias power to the lower electrode 18. Process ST3 is executed by the third control based on the control unit 80.

[0070] In one embodiment, the control unit 80 may further perform a fourth control. The fourth control is performed after the third control. The fourth control includes controlling the gas supply unit 120 and the plasma generation unit to generate a fourth plasma from the fourth processing gas within the chamber 10 to further etch the PCL layer of the substrate W supported by the substrate support 16. In one embodiment, the fourth control includes controlling the gas supply unit 120 to supply the fourth processing gas into the chamber 10. The fourth control may also include controlling the exhaust device 50 to set the pressure within the chamber 10 to a specified pressure. The fourth control further includes controlling the plasma generation unit to generate plasma from the fourth processing gas within the chamber 10. In the fourth control, the control unit 80 controls the high-frequency power supply 150A and the high-frequency power supply 150B respectively to supply high-frequency power to the inner antenna element 142A and the outer antenna element 142B. The fourth control may also include controlling the high-frequency power supply 64 to supply high-frequency bias power to the lower electrode 18. Process ST4 is executed by the fourth control based on the control unit 80.

[0071] The above descriptions have illustrated various exemplary embodiments, but the embodiments are not limited to these exemplary embodiments. Various additions, omissions, substitutions, and modifications can be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

[0072] For example, in another embodiment, the plasma processing apparatus can be a plasma processing apparatus other than an inductively coupled plasma processing apparatus. Such a plasma processing apparatus can be a capacitively coupled plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, or a plasma processing apparatus that uses surface waves such as microwaves to generate plasma.

[0073] Based on the above description, it should be understood that the various embodiments of the present invention have been described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of the invention. Therefore, it is not intended that the various embodiments disclosed in this specification are limited, and the actual scope and spirit are indicated by the appended technical solutions.

Claims

1. An etching method, comprising: (a) The process of etching a titanium nitride film using a first plasma; and (b) The process of etching the titanium nitride film using a second plasma. The first plasma is generated by the first processing gas, and the second plasma is generated by the second processing gas. One of the first processing gas and the second processing gas contains chlorine-containing gas and fluorocarbon gas. The first processing gas and the other of the second processing gas contain chlorine gas but do not contain fluorocarbon gas. Repeatedly execute the loop including (a) and (b) described above. The repetition of the cycle is stopped when the titanium nitride film is partially etched in its thickness direction, so that the titanium nitride film provides a bottom surface between its upper and lower surfaces.

2. The etching method according to claim 1, wherein, The substrate having the titanium nitride film also has a phase change material layer. The titanium nitride film is disposed on the phase change material layer. The etching method further includes a step of etching the portion between the bottom surface and the lower surface of the titanium nitride film and a portion of the phase change material layer in the thickness direction using a third plasma generated by a third processing gas.

3. The etching method according to claim 2, wherein, The third processing gas contains bromine-containing gas.

4. The etching method according to claim 2 or 3, wherein, The phase change material layer is formed of germanium, antimony and tellurium.

5. The etching method according to claim 2 or 3, further comprising: The process of further etching the phase change material layer using a fourth plasma generated by a fourth processing gas.

6. The etching method according to claim 5, wherein, The fourth processing gas includes hydrogen and hydrocarbon gas.

7. The etching method according to any one of claims 1 to 3, wherein, The time lengths of (a) and (b) in the cycle are respectively more than 1 second and less than 3 seconds.

8. A plasma processing apparatus comprising: chamber; A substrate support configured to support a substrate within the cavity; A gas supply unit configured to supply a first processing gas and a second processing gas to the chamber; A plasma generation unit configured to generate plasma from gas within the chamber; and The control unit is configured to control the gas supply unit and the plasma generation unit. One of the first processing gas and the second processing gas contains chlorine-containing gas and fluorocarbon gas. The first processing gas and the other of the second processing gas contain chlorine gas but do not contain fluorocarbon gas. The control unit is configured to repeatedly execute the following control loop, which includes: A first control controls the gas supply unit and the plasma generation unit to generate a first plasma from the first processing gas in the chamber to etch the titanium nitride film of the substrate supported by the substrate support. as well as A second control unit controls the gas supply unit and the plasma generation unit to generate a second plasma from the second processing gas within the chamber to etch the titanium nitride film. The repetition of the control cycle is stopped when the titanium nitride film is partially etched in its thickness direction, so that the titanium nitride film provides a bottom surface between its upper and lower surfaces.

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