Substrate processing method and substrate processing apparatus

Abstract

To remove a reaction product deposited by an etching step and containing transition metal.SOLUTION: Provided is a substrate processing method comprising the steps of: preparing a substrate with a laminate film formed thereon and having at least an etching-target film, a ground layer disposed on a lower layer of the etching-target film, and a mask disposed an upper layer of the etching-target film; etching the etching-target film through the mask by plasma; and making a thermal treatment on the substrate at a desired temperature after the etching step, provided that at least one of the mask and the ground layer contains transition metal.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. [Background technology]

[0002] A method is known for etching holes with a high aspect ratio in a low-temperature environment in a semiconductor wafer having a silicon oxide layer and a silicon nitride layer stacked thereon (see, for example, Patent Document 1). When etching a film to be etched that contains silicon nitride using a hydrogen-containing gas, reaction products are generated and are deposited on the surface and side walls of the film to be etched after the etching process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-207840 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a substrate processing method and a substrate processing apparatus capable of removing reaction products containing transition metals deposited by an etching process. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, a method for manufacturing a semiconductor device includes the steps of: preparing a substrate on which a laminated film is formed, the laminated film including at least a film to be etched, a base layer disposed below the film to be etched, and a mask disposed above the film to be etched; etching the film to be etched through the mask by plasma; and, after the etching step, The above heat treating the substrate at a desired temperature; After the heat treatment step, the substrate is washed with hydrofluoric acid; At least one of the mask and the underlayer contains a transition metal. and when a first temperature is set to a value lower than a temperature at which a first reaction product containing the transition metal, which is generated in the etching step and deposited on at least one of the etching target film and the mask, reacts with oxygen O to form a metal oxide, the heat treatment step sets a desired temperature of the substrate lower than the first temperature. A method for processing a substrate is provided. Effect of the Invention

[0006] According to one aspect, the deposited reaction products containing the transition metal can be removed by the etching process. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of a substrate processing system according to an embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of a substrate processing apparatus (etching and plasma ashing) according to an embodiment. [Diagram 3] FIG. 2 is a diagram showing an example of a substrate processing apparatus (radical ashing) according to an embodiment. [Figure 4] 1A and 1B are diagrams showing an example of a film structure formed on a substrate according to an embodiment. [Diagram 5] 4 is a flowchart showing an example of a substrate processing method according to the embodiment. [Figure 6] 10 is a flowchart showing another example of a substrate processing method according to the embodiment. [Figure 7] 5A and 5B are diagrams showing examples of an etching rate and a mask selectivity with respect to a substrate temperature according to the embodiment. [Figure 8] FIG. 2 is a graph showing a vapor pressure curve of a tungsten-containing gas versus temperature. [Figure 9] FIG. 13 is a diagram showing an example of generation of tungsten residue according to the embodiment. [Figure 10] FIG. 4 is a graph showing the relationship between the ashing rate of an organic resist coating film and the substrate temperature according to the embodiment. [Figure 11] FIG. 13 is a graph showing the amount of tungsten-containing residue, ammonium fluorosilicate residue, and CF polymer residue versus substrate temperature according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0009] [Substrate processing system] First, an example of a substrate processing system 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of a substrate processing system 1 according to an embodiment. In the substrate processing system 1, a substrate processing method including an etching process and a heat treatment process according to an embodiment is performed. However, without being limited thereto, the substrate processing system 1 may also perform an etching process and an ashing process. Alternatively, a substrate processing method including an etching process, a heat treatment process and an ashing process may be performed.

[0010] The substrate processing system 1 includes processing chambers 211-214, a vacuum transfer chamber 220, load lock chambers 231 and 232, an atmospheric transfer chamber 240, load ports 251-253, gate valves 261-268, and a control unit 270.

[0011] The processing chamber 211 has a stage ST on which a substrate W is placed, and is connected to the vacuum transfer chamber 220 via a gate valve 261. Similarly, the processing chamber 212 has a stage ST on which a substrate is placed, and is connected to the vacuum transfer chamber 220 via a gate valve 262. The processing chamber 213 has a stage ST on which a substrate is placed, and is connected to the vacuum transfer chamber 220 via a gate valve 263. The processing chamber 214 has a stage ST on which a substrate is placed, and is connected to the vacuum transfer chamber 220 via a gate valve 264. The insides of the processing chambers 211 to 214 are depressurized to a predetermined vacuum atmosphere, and the substrate is subjected to a desired process (etching process, heat treatment, ashing process, etc.) therein. The operation of each part for processing in the processing chambers 211 to 214 is controlled by the control unit 270.

[0012] The inside of the vacuum transfer chamber 220 is depressurized to a predetermined vacuum atmosphere. A transfer mechanism 221 is provided in the vacuum transfer chamber 220. The transfer mechanism 221 transfers substrates to the processing chambers 211 to 214 and the load lock chambers 231 and 232. The operation of the transfer mechanism 221 is controlled by the control unit 270.

[0013] The load lock chamber 231 has a stage 231a on which a substrate is placed, is connected to the vacuum transfer chamber 220 via a gate valve 265, and is connected to the atmospheric transfer chamber 240 via a gate valve 267. Similarly, the load lock chamber 232 has a stage 232a on which a substrate is placed, is connected to the vacuum transfer chamber 220 via a gate valve 266, and is connected to the atmospheric transfer chamber 240 via a gate valve 268. The inside of the load lock chambers 231 and 232 can be switched between an atmospheric atmosphere and a vacuum atmosphere. The switching between the vacuum atmosphere and the atmospheric atmosphere in the load lock chambers 231 and 232 is controlled by the control unit 270.

[0014] The atmosphere inside the atmospheric transfer chamber 240 is atmospheric, and for example, a downflow of clean air is formed. A transfer mechanism 241 is provided in the atmospheric transfer chamber 240. The transfer mechanism 221 transfers substrates to the load lock chambers 231, 232 and carriers C of the load ports 251 to 253 described later. The operation of the transfer mechanism 241 is controlled by the control unit 270.

[0015] The load ports 251 to 253 are provided on the long side wall of the atmospheric transfer chamber 240. Carriers C accommodating substrates or empty carriers C are attached to the load ports 251 to 253. As the carriers C, for example, a FOUP (Front Opening Unified Pod) or the like can be used.

[0016] The gate valves 261 to 268 are configured to be openable and closable. The opening and closing of the gate valves 261 to 268 is controlled by the control unit 270.

[0017] The control unit 270 controls the entire substrate processing system 1 by controlling the operations of the processing chambers 211-214, the transfer mechanisms 221, 241, the opening and closing of the gate valves 261-268, switching between a vacuum atmosphere and an air atmosphere in the load lock chambers 231, 232, and the like.

[0018] Next, a description will be given of an example of the operation of the substrate processing system 1. For example, the control unit 270 opens the gate valve 267 and controls the transfer mechanism 241 to transfer, for example, a substrate accommodated in the carrier C of the load port 251 to the stage 231a of the load lock chamber 231. The control unit 270 closes the gate valve 267 and creates a vacuum atmosphere inside the load lock chamber 231.

[0019] The control unit 270 opens the gate valves 261, 265 and controls the transfer mechanism 221 to transfer the substrate in the load lock chamber 231 to the stage ST of the processing chamber 211. The control unit 270 closes the gate valves 261, 265 and operates the processing chamber 211. As a result, a predetermined process (e.g., etching process, etc.) is performed on the substrate in the processing chamber 211.

[0020] Next, the control unit 270 opens the gate valves 261, 263 and controls the transfer mechanism 221 to transfer the substrate processed in the processing chamber 211 to the stage ST of the processing chamber 213. The control unit 270 closes the gate valves 261, 263 and operates the processing chamber 213. As a result, a predetermined process (for example, a heat treatment to be described later) is performed on the substrate in the processing chamber 213.

[0021] The control unit 270 may transport the substrate processed in the processing chambers 211, 212 to the stage ST of the processing chambers 213, 214. In this embodiment, the substrate processed in the processing chambers 211, 212 may be transported to the processing chamber 213 or the processing chamber 214 depending on the operating state of the processing chamber 213 and the processing chamber 214, and an ashing process may be performed. The control unit 270 can perform a predetermined process (e.g., etching process, heat treatment, etc.) on multiple substrates in parallel using the processing chambers 213 and 214. This can increase productivity.

[0022] The control unit 270 controls the transfer mechanism 221 to transfer the substrate that has been heat-treated after etching (or the substrate that has been ashed) to the stage 231a of the load lock chamber 231 or the stage 232a of the load lock chamber 232. The control unit 270 sets the inside of the load lock chamber 231 or the load lock chamber 232 to an atmospheric air. The control unit 270 opens the gate valve 267 or the gate valve 268, and controls the transfer mechanism 241 to transfer the substrate in the load lock chamber 232 to, for example, the carrier C of the load port 253 and store it therein.

[0023] In this manner, according to the substrate processing system 1 shown in FIG. 1, while the substrate is being processed in each processing chamber, the substrate can be subjected to etching processing, heat treatment, ashing processing, etc. without being exposed to the atmosphere, i.e., without breaking the vacuum.

[0024] [Substrate processing equipment] Next, a substrate processing apparatus for implementing at least one of the processing chambers 211-214 will be described with reference to Figs. 2 and 3. Figs. 2 and 3 are diagrams showing an example of a substrate processing apparatus according to an embodiment. In the substrate processing apparatus 2 of Fig. 2, a plasma etching process and / or a plasma ashing process is performed on a substrate W. In the substrate processing apparatus 3 of Fig. 3, a baking process or a radical ashing process is performed on a substrate W.

[0025] In the baking process, the reaction product containing silicon Si, nitrogen N, and fluorine F is sublimated and removed by the thermal energy that heats the substrate W. The reaction product containing silicon Si, nitrogen N, and fluorine F is generated in the etching process, and an example of the reaction product containing silicon Si, nitrogen N, and fluorine F that is deposited on the film to be etched is ammonium silicofluoride. The reaction product containing silicon Si, nitrogen N, and fluorine F is an example of a second reaction product. The baking process is an example of a process of heat treating the substrate W.

[0026] The second reaction product includes a reaction product containing nitrogen N, hydrogen H, and a halogen, which is generated in the etching process and deposited on the film to be etched. An example of a reaction product containing nitrogen N, hydrogen H, and a halogen is ammonium halide. The second reaction product may include at least one of ammonium, ammonium chloride, ammonium bromide, and ammonium iodide.

[0027] In the ashing process using plasma (hereinafter also referred to as "plasma ashing"), the supply of radicals in the plasma and ion irradiation energy from the plasma are used to remove the organic film mask. In the plasma ashing process, reaction products containing carbon (C) and fluorine (F) generated in the etching process are also removed. Reaction products containing carbon (C) and fluorine (F), such as CF polymers, generated in the etching process are an example of a third reaction product.

[0028] In the radical ashing process (hereinafter also referred to as "radical ashing"), ions from plasma are not used, but the organic film mask is removed by supplying radicals and by thermal energy for heating the substrate W. In the radical ashing process, reaction products containing carbon C and fluorine F that are generated in the etching process are also removed.

[0029] The ashing rate is different between the plasma ashing process and the radical ashing process. In the plasma ashing process, radicals and ions are used for ashing, so the ashing rate is higher than in the radical etching process in which radicals are used for ashing. In addition, the temperature ranges controlled are different between the plasma ashing process and the radical ashing process. Both the radical ashing process and the plasma ashing process are also examples of processes for heat treating the substrate W, since temperature control is performed on the substrate W.

[0030] (Substrate processing device 2) Hereinafter, first, a substrate processing apparatus 2 capable of performing a plasma ashing process will be described with reference to Fig. 2. The substrate processing apparatus 2 may perform an etching (plasma etching) process, and then perform a plasma ashing process.

[0031] The substrate processing apparatus 2 has a processing vessel 10. The processing vessel 10 provides a processing chamber 10s therein. The processing vessel 10 includes a main body 12. The main body 12 has a substantially cylindrical shape. The main body 12 is made of, for example, aluminum. A corrosion-resistant film is provided on the inner wall surface of the main body 12. The corrosion-resistant film may be an oxide film made of ceramics such as alumina (aluminum oxide) or yttrium oxide and subjected to anodizing treatment.

[0032] A passage 12p is formed in a side wall of the main body 12. The substrate W passes through the passage 12p when being transferred between the processing chamber 10s and the outside of the processing container 10. The passage 12p can be opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the main body 12.

[0033] A support 13 is provided on the bottom of the main body 12. The support 13 is made of an insulating material. The support 13 has a substantially cylindrical shape. The support 13 extends upward from the bottom of the main body 12 within the processing chamber 10s. An edge ring 25 (also called a focus ring) that surrounds the periphery of the substrate is provided on the support 13. The edge ring 25 has a substantially cylindrical shape and may be made of silicon or the like.

[0034] The substrate processing apparatus 2 further includes a stage ST. The stage ST is supported by a support 13. The stage ST is provided in a processing chamber 10s, and is configured to support a substrate W.

[0035] The stage ST includes a lower electrode 18 and an electrostatic chuck 20 according to an exemplary embodiment. The stage ST may further include an electrode plate 16. The electrode plate 16 is made of a conductor such as aluminum and has a substantially disk-like shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is made of a conductor such as aluminum and has a substantially disk-like shape. The lower electrode 18 is electrically connected to the electrode plate 16. The outer peripheral surface of the lower electrode 18 and the outer peripheral surface of the electrode plate 16 are surrounded by a support 13.

[0036] The electrostatic chuck 20 is provided on a lower electrode 18. The electrode of the electrostatic chuck 20 is connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrode, the substrate W is held on the electrostatic chuck 20 by electrostatic attraction. The electrostatic chuck 20 supports the substrate W and an edge ring 25. The electrode plate 16 and the lower electrode 18 are an example of a base that supports the electrostatic chuck 20.

[0037] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., a refrigerant) is supplied to the flow path 18f from a chiller unit provided outside the processing vessel 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f is returned to the chiller unit via a pipe 22b. In the substrate processing apparatus 2, the temperature of the substrate W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18.

[0038] The substrate processing apparatus 2 is provided with a gas supply line 24. The gas supply line 24 supplies a heat transfer gas (for example, He gas) from a heat transfer gas supply mechanism between the upper surface of the electrostatic chuck 20 and the lower surface of the substrate W.

[0039] The substrate processing apparatus 2 further includes an upper electrode 30. The upper electrode 30 is provided above the stage ST. The upper electrode 30 is supported on the upper part of the main body 12 via a member 32. The member 32 is made of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the main body 12.

[0040] The upper electrode 30 may include a top plate 34 and a support 36. The bottom surface of the top plate 34 is the bottom surface on the processing chamber 10s side and defines the processing chamber 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor with little Joule heat. A plurality of gas discharge holes 34a are formed in the top plate 34. The plurality of gas discharge holes 34a penetrate the top plate 34 in the plate thickness direction.

[0041] The support 36 detachably supports the top plate 34. The support 36 is made of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support 36. A plurality of gas holes 36b are formed in the support 36. The plurality of gas holes 36b extend downward from the gas diffusion chamber 36a. The plurality of gas holes 36b are connected to the plurality of gas discharge holes 34a, respectively. A gas inlet 36c is formed in the support 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

[0042] A gas supply unit GS including a gas source group 40, a flow rate controller group 44, and a valve group 42 is connected to the gas supply pipe 38. The gas source group 40 is connected to the gas supply pipe 38 via the flow rate controller group 44 and the valve group 42. The gas source group 40 includes a plurality of gas sources. The valve group 42 includes a plurality of opening and closing valves. The flow rate controller group 44 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers of the flow rate controller group 44 is a mass flow controller or a pressure control type flow rate controller. Each of the plurality of gas sources of the gas source group 40 is connected to the gas supply pipe 38 via a corresponding flow rate controller of the flow rate controller group 44 and a corresponding opening and closing valve of the valve group 42. The power source 70 is connected to the upper electrode 30. The power source 70 applies a voltage to the upper electrode 30 to draw positive ions present in the processing chamber 10s to the top plate 34.

[0043] In the substrate processing apparatus 2, a shield 46 is detachably provided along the inner wall surface of the main body 12. The shield 46 is also provided on the outer periphery of the support portion 13. The shield 46 prevents reaction products such as etching by-products from adhering to the main body 12. The shield 46 is formed, for example, by forming a corrosion-resistant film on the surface of a member made of aluminum. The corrosion-resistant film can be an oxide film such as alumina or yttrium oxide.

[0044] A baffle plate 48 is provided between the support 13 and the side wall of the main body 12. The baffle plate 48 is formed by forming a corrosion-resistant film on the surface of a member made of aluminum, for example. The corrosion-resistant film may be an oxide film such as alumina or yttrium oxide. A plurality of through holes are formed in the baffle plate 48. An exhaust port 12e is provided below the baffle plate 48 and at the bottom of the main body 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 has a pressure regulating valve and a vacuum pump such as a turbo molecular pump.

[0045] The substrate processing apparatus 2 includes a first high frequency power supply 62 that applies high frequency HF power for generating plasma. The first high frequency power supply 62 is configured to generate high frequency HF power in order to generate plasma from the gas in the processing chamber 10. The frequency of the high frequency HF is, for example, within a range of 27 MHz to 100 MHz.

[0046] The first high frequency power supply 62 is electrically connected to the lower electrode 18 via a matching box 66. The matching box 66 has a matching circuit. The matching circuit of the matching box 66 is configured to match the impedance of the load side (lower electrode side) of the first high frequency power supply 62 to the output impedance of the first high frequency power supply 62. In another embodiment, the first high frequency power supply 62 may be electrically connected to the upper electrode 30 via the matching box 66.

[0047] The substrate processing apparatus 2 may further include a second high frequency power supply 64 that applies high frequency LF power for attracting ions. The second high frequency power supply 64 is configured to generate high frequency LF power. The high frequency LF has a frequency suitable for mainly attracting ions into the substrate W, and is, for example, a frequency within a range of 400 kHz to 13.56 MHz. Alternatively, the high frequency LF may be a pulsed voltage having a rectangular waveform.

[0048] The second high frequency power supply 64 is electrically connected to the lower electrode 18 via a matching box 68. The matching box 68 has a matching circuit. The matching circuit of the matching box 68 is configured to match the impedance of the load side (lower electrode side) of the second high frequency power supply 64 to the output impedance of the second high frequency power supply 64.

[0049] The substrate processing apparatus 2 may further include a second control unit 80. The second control unit 80 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, and the like. The second control unit 80 controls each unit of the substrate processing apparatus 2. In the second control unit 80, an operator can use the input device to input commands and the like to manage the substrate processing apparatus 2. In addition, the second control unit 80 can visualize and display the operating status of the substrate processing apparatus 2 using the display device. Furthermore, a control program and recipe data are stored in the storage unit of the second control unit 80. The control program is executed by the processor of the second control unit 80 to execute various processes in the substrate processing apparatus 2. The processor of the second control unit 80 executes the control program and controls each unit of the substrate processing apparatus 2 according to the recipe data, whereby various processes, for example, a plasma processing method, are executed in the substrate processing apparatus 2.

[0050] (Substrate processing device 3) Next, a substrate processing apparatus 3 capable of performing a radical ashing process will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the substrate processing apparatus 3. The substrate processing apparatus 3 has a processing container 101 and a control unit 130. The substrate processing apparatus 3 in this embodiment performs a radical ashing process on an organic film formed on a substrate W by using ICP (Inductively Coupled Plasma).

[0051] The substrate processing apparatus 3 has a substantially cylindrical airtight processing vessel 101 whose inner wall surface is formed of, for example, aluminum that has been anodized. The processing vessel 101 is grounded. The processing vessel 101 is divided into upper and lower sections by an upper top plate 102, and the upper surface side of the upper top plate 102 is an antenna chamber 103 in which an antenna 113 is housed, and the lower surface side of the upper top plate 102 is a processing chamber 104 in which plasma is generated. In this embodiment, the upper top plate 102 is made of quartz and constitutes the ceiling wall of the processing chamber 104. The upper top plate 102 may be made of ceramics such as Al2O3.

[0052] An ion trap 111 made of quartz and formed into a plate shape is provided below the upper top plate 102. The ion trap 111 divides the space inside the processing chamber 104 into upper and lower spaces S1 and S2. The ion trap 111 suppresses the intrusion of ions contained in the plasma generated in the space S1 into the space S2. The ion trap 111 has a large number of through-holes 112 formed therein, which penetrate in the thickness direction of the ion trap 111, and electrons and radicals contained in the plasma generated in the space S1 can intrude into the space S2 through the respective through-holes 112.

[0053] A gas supply pipe 124 is provided on the side wall 104a of the processing chamber 104, one end of which is connected to the space S1 and the other end of which is connected to the gas supply mechanism 120. Gas supplied from the gas supply mechanism 120 is supplied into the space S1 through the gas supply pipe 124. The gas supply mechanism 120 includes a gas source group 121, a flow rate controller group 122, and a valve group 123.

[0054] The valve group 123 includes a plurality of on-off valves. The flow rate controller group 122 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers in the flow rate controller group 122 is a mass flow controller or a pressure-controlled flow rate controller. The gas source group 121 supplies a plurality of gases such as an oxygen-containing gas and an inert gas. The oxygen-containing gas is, for example, O2 gas, and the inert gas is, for example, Ar or N2 gas. Each of the plurality of gas sources in the gas source group 121 is connected to a gas supply pipe 124 via a corresponding flow rate controller in the flow rate controller group 122 and a corresponding on-off valve in the valve group 123. The gas supply mechanism 120 is an example of a gas supply unit.

[0055] An antenna 113 is disposed within the antenna chamber 103. The antenna 113 has an antenna wire 113a formed of a highly conductive metal such as copper or aluminum. The antenna wire 113a is formed in any shape such as a ring or a spiral. The antenna 113 is separated from the upper top plate 102 by a spacer 117 formed of an insulating material.

[0056] One end of a power supply member 116 extending upward from the antenna chamber 103 is connected to a terminal 118 of the antenna line 113a. One end of a power supply line 119 is connected to the other end of the power supply member 116, and the other end of the power supply line 119 is connected to a high-frequency power source 115 via a matching device 114. The high-frequency power source 115 supplies high-frequency power of, for example, a frequency of 13.56 MHz to the antenna 113 via the matching device 114, the power supply line 119, the power supply member 116, and the terminal 118. As a result, an induced electric field is formed in the space S1 in the processing chamber 104 below the antenna 113, and the gas supplied from the gas supply pipe 124 is turned into plasma by this induced electric field, generating an inductively coupled plasma in the space S1. The antenna 113 is an example of a plasma generating unit.

[0057] A stage ST on which the substrate W is placed is provided on the bottom wall of the processing chamber 104 via a spacer 126 made of an insulating material. The stage ST has a base 131 provided on the spacer 126, an electrostatic chuck 132 provided on the base 131, and a protective member 133 made of an insulating material and covering the side walls of the base 131 and the electrostatic chuck 132. The base 131 and the electrostatic chuck 132 have a circular shape corresponding to the shape of the substrate W, and the entire stage ST is formed into a cylindrical shape. The spacer 126 and the protective member 133 are made of insulating ceramics such as alumina.

[0058] The electrostatic chuck 132 is provided on the upper surface of the base material 131. The electrostatic chuck 132 has a dielectric layer 145 made of a ceramic sprayed film and an electrode 146 embedded inside the dielectric layer 145. The electrode 146 can have various shapes, such as a plate shape, a film shape, a lattice shape, a mesh shape, and the like. A DC power supply 148 is connected to the electrode 146 via a power supply line 147, and a DC voltage supplied from the DC power supply 148 is applied to the electrode 146. The DC voltage applied to the electrode 146 from the DC power supply 148 via the power supply line 147 is controlled by a switch (not shown). The DC voltage applied from the DC power supply 148 generates an electrostatic adsorption force such as a Coulomb force or a Johnsen-Rahbek force in the electrode 146, and the substrate W placed on the electrostatic chuck 132 is adsorbed and held on the upper surface of the electrostatic chuck 132. The dielectric layer 145 of the electrostatic chuck 132 can be made of Al2O3, Y2O3, or the like.

[0059] A temperature adjustment mechanism and a temperature sensor (neither of which is shown) for controlling the temperature of the substrate W are provided in the base material 131 of the stage ST. A temperature adjustment mechanism and a temperature sensor (neither of which is shown) for controlling the temperature of the gas in the processing chamber 104 are also provided in the side wall 104a of the processing chamber 104. The processing vessel 101 is also provided with a heat transfer gas supply mechanism (not shown) for supplying a heat transfer gas, for example, He gas, between the substrate W and the stage ST in a state in which the substrate W is placed on the stage ST to adjust the amount of heat transfer between the substrate W and the stage ST. Furthermore, the stage ST is provided with a plurality of lift pins (not shown) for transferring the substrate W so as to be capable of projecting and retracting from the upper surface of the electrostatic chuck 132.

[0060] A load / unload port 155 is provided on the side wall 104a of the processing chamber 104 for loading the substrate W into the processing chamber 104 and unloading the substrate W from the processing chamber 104, and the load / unload port 155 can be opened and closed by a gate valve G. By controlling the gate valve G to an open state, the substrate W can be loaded and unloaded through the load / unload port 155.

[0061] An exhaust port 159 is formed in the bottom wall of the processing chamber 104, and an exhaust mechanism 160 is provided at the exhaust port 159. The exhaust mechanism 160 has an APC (Auto Pressure Controller) valve 162 and a vacuum pump 163 that exhausts the inside of the processing chamber 104 via an exhaust pipe 161. The APC valve 162 adjusts the aperture of the exhaust pipe 161 connected to the exhaust port 159 to control the pressure inside the processing chamber 104. The processing chamber 104 is exhausted by the vacuum pump 163, and during the etching process using plasma, the aperture of the APC valve 162 is adjusted to maintain the inside of the processing chamber 104 at a predetermined vacuum level.

[0062] The control unit 130 includes a memory such as a Read Only Memory (ROM) or a Random Access Memory (RAM), and a processor such as a Central Processing Unit (CPU). The processor in the control unit 130 reads and executes a program stored in the memory in the control unit 130 to control each part of the processing vessel 101.

[0063] [Membrane structure] Next, a film structure formed on the substrate W according to the embodiment will be described with reference to FIG. 4. FIG. 4 is a diagram showing an example of a film structure formed on the substrate W according to the embodiment. As shown in FIG. 4(a), the substrate W has an etching target film 300 formed by alternately stacking silicon oxide (SiO2) layers 300a and silicon nitride (SiN) layers 300b as an example of an etching target film. A tungsten layer 303 as an example of a base layer is disposed under the etching target film 300. A mask 301 is disposed over the etching target film 300. Note that this film structure is an example, and the substrate W may have a laminated film having at least the etching target film, the base layer disposed under the etching target film, and the mask disposed over the etching target film. The tungsten layer 303 may be a tungsten-containing film.

[0064] For example, the underlayer may be a transition metal other than the tungsten layer 303. Also, the present invention is not limited to this, and at least one of the mask 301 and the underlayer may contain a transition metal. In this embodiment, the tungsten layer 303 is disposed below the hole H formed in the mask 301 at a position corresponding to the hole H.

[0065] In the etching process, the film 300 to be etched is etched using a transition metal as an underlayer. In this embodiment, the film 300 to be etched is etched using a tungsten layer 303 as an underlayer. In etching performed by controlling the substrate temperature to 0° C. or less (hereinafter referred to as "low-temperature etching"), reaction products containing transition metals are generated. FIG. 4(b) shows an example of a state when etching has progressed until the tungsten layer 303 is exposed by low-temperature etching. Reaction products 304 containing tungsten are deposited on the tungsten layer 303 and on the sidewalls of the film 300 to be etched.

[0066] Even when a transition metal is used for the mask, a reaction product containing the transition metal is generated by low-temperature etching. The reaction product containing a transition metal such as tungsten that is deposited on at least one of the etching target film 300 and the mask 301 by low-temperature etching is an example of a first reaction product. The first reaction product may be a halide of the transition metal. For example, when a tungsten layer 303 is used as the underlayer, the first reaction product may be a halide of tungsten.

[0067] A gas containing a CF-based gas is used to etch the film 300 to be etched. The film 300 to be etched is etched through a mask 301 using plasma of the CF-based gas, thereby forming holes H and slit-shaped grooves in the film 300 to be etched. When the silicon oxide layer 300a and the silicon nitride layer 300b are etched using plasma of the CF-based gas or CHF-based gas, a reaction product of ammonium silicofluoride (AFS) is generated during the etching process and is deposited on the film 300 to be etched. The reaction product of ammonium silicofluoride is an example of a second reaction product containing nitrogen N, hydrogen H, and a halogen.

[0068] The second reaction product that is deposited on the film to be etched may be an ammonium halide. The second reaction product may include at least one of ammonium, ammonium chloride, ammonium bromide, and ammonium iodide.

[0069] [Substrate processing method] An example of a substrate processing method according to the present embodiment for processing a substrate W having the above-mentioned film structure will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a flowchart showing an example of the substrate processing method according to the embodiment. Fig. 6 is a flowchart showing another example of the substrate processing method according to the embodiment.

[0070] In the substrate processing method of Fig. 5, a substrate W having a laminated film formed thereon is prepared, the laminated film having at least a film to be etched 300, a tungsten layer 303 disposed under the film to be etched 300, and a mask 301 disposed over the film to be etched 300 (step S1). Next, the film to be etched 300 is etched through the mask 301, for example, by radicals (step S2: main etching). After etching, the substrate W is heat-treated while being controlled to a desired temperature (step S3), and this process is completed. In the heat treatment, mainly reaction products of ammonium silicofluoride are removed. The heat treatment includes radical ashing and baking.

[0071] When the substrate W is exposed to the atmosphere while the reaction products of ammonium silicofluoride are deposited thereon, the reaction products react with moisture in the atmosphere. As the exposure time to the atmosphere increases, the side surfaces of the silicon nitride layer 300b are likely to be dented (side etched), and foreign matter that swells due to reaction with moisture is likely to be generated on the side walls of the silicon nitride layer 300b. This causes damage to the laminated film and blockage of the holes H, adversely affecting subsequent processes and causing a decrease in yield. In order to minimize such a decrease in yield, it is necessary to manage the time during which the substrate W is exposed to the atmosphere between the end of etching and the next substrate processing process so as to be as short as possible.

[0072] Therefore, it is important to remove ammonium silicofluoride before exposing the substrate W to the atmosphere. It is also possible to use wet cleaning using pure water or a chemical solution to remove ammonium silicofluoride. However, in this case, the substrate W must be exposed to the atmosphere in order to perform the wet cleaning. In other words, wet cleaning may cause side etching or swelling foreign matter on the substrate, which may damage the silicon nitride layer 300b. In addition, there is a concern that the throughput may decrease because an additional process of wet cleaning is required.

[0073] In contrast, in the substrate processing system 1 according to the present embodiment, after the etching process, the substrate W can be heat-treated without being exposed to the atmosphere. This makes it possible to remove ammonium silicofluoride and prevent damage to the laminated film.

[0074] In the substrate processing method shown in FIG. 6, a substrate W on which a laminated film is formed is prepared in the same manner as in step S1 in FIG. 5 (step S1). Next, the etching target film 300 is etched by plasma through a mask 301 (step S2). After etching, the substrate W is subjected to an ashing process while being controlled to a desired temperature (step S4), and this process is completed. In the ashing process, the mask 301 is removed. It is also possible to remove reaction products containing ammonium silicofluoride and CF polymer. The ashing process in step S4 is also included as an example of a heat treatment. The reaction product containing CF polymer is an example of a third reaction product containing carbon C and fluorine F. The third reaction product is generated in the etching process and is deposited on the etching target film 300.

[0075] The etching step and the heat treatment step (ashing step) are performed without exposing the substrate W to the atmosphere. That is, the processes of steps S2 and S3 in Fig. 5 and the processes of steps S2 and S4 in Fig. 6 may be performed in the same processing chamber among the processing chambers 211-214 of the substrate processing system 1 in which the substrate W is not exposed to the atmosphere, or may be performed in different processing chambers.

[0076] The conditions for each step are shown below.

[0077] (Etching process) Gas conditions: H2 gas / C4F8 gas Processing chamber pressure: 30mTorr (4.0Pa) Wafer temperature during processing: 0°C (substrate temperature) First high frequency: 40M~100MHz, 3kW, continuous wave Second high frequency: 400k~3MHz, 6kW, continuous wave (Heat treatment process: baking) Gas conditions: O2 gas / N2 gas, or N2 gas Processing chamber pressure: 1.3 Torr (173 Pa) Wafer temperature during processing: 250℃ (stage temperature) (Heat treatment process: radical ashing process) Gas conditions: O2 gas / N2 gas Chamber pressure: 1.3 Torr Wafer temperature during processing: 50 to 300°C (stage temperature) Plasma source ICP (Heat treatment process: plasma ashing process) Gas condition: O2 gas Processing chamber pressure: 400mTorr (53.3Pa) Wafer temperature during processing: -30 to 50°C (stage temperature) First high frequency: 40M~100MHz, 1.5kW, continuous wave

[0078] [Low temperature etching] The characteristics of low-temperature etching will be described with reference to Fig. 7. Fig. 7 is a graph showing the etching rate (Fig. 7(a)) of the film 300 to be etched (a laminated film of a silicon oxide layer 300a and a silicon nitride layer 300b) and the mask selectivity (Fig. 7(b)) on the vertical axis against the substrate temperature on the horizontal axis. The mask selectivity is the ratio of the etching rate of the film 300 to be etched to the etching rate of the mask 301.

[0079] 7(a) and (b), the etching rate and mask selectivity of the etching target film 300 can be improved by low-temperature etching in which the substrate temperature is controlled to a low temperature range (e.g., 0° C. or lower). Regarding the etching rate, the etching rates of the silicon oxide layer 300a and the silicon nitride layer 300b are increased.

[0080] However, in low-temperature etching, the substrate temperature is controlled to a low temperature below 0°C, so there is a large temperature difference between the etching process and the subsequent heat treatment process (ashing process), and it takes time to heat up the processing chamber, resulting in reduced throughput.

[0081] Furthermore, there is a problem regarding the transport of radicals when a silicon layer 302 is used as an underlying layer of the film 300 to be etched in the etching process (see FIG. 4(a)). For example, when the underlying layer is the silicon layer 302 under the set conditions (pressure in the process chamber=30 mT (4.0 Pa), substrate temperature≦0° C.), the Si-F-based gas generated during etching vaporizes, and the CF-based precursor cannot be supplied to the bottom of the hole H. As a result, the protective film containing C is not deposited at the bottom of the hole H, and the silicon layer 302 is etched away, making it impossible to ensure the underlying selectivity. The underlying selectivity is the ratio of the etching rate of the film 300 to the etching rate of the underlying layer (e.g., the silicon layer 302).

[0082] In order to ensure the underlayer selectivity, an over-etching step may be performed after the main etching step of step S2 in Fig. 5 or 6, in which the substrate temperature is increased to allow carbon radicals to reach the bottom of hole H. However, in the over-etching step, the substrate temperature is controlled to 0°C or higher, resulting in an etching rate lower than that obtained by low-temperature etching, which reduces throughput and decreases productivity.

[0083] Therefore, in the film structure according to this embodiment, as shown in Fig. 4(a), a tungsten layer 303 is disposed as an underlayer below a hole H formed in a mask 301. This allows low-temperature etching in the etching process, and the etching target film 300 is etched at a high etching rate. When the underlayer is exposed at the bottom of the hole H in the etching target film 300, the tungsten layer 303 is exposed instead of the silicon layer 302, as shown in Fig. 4(b), and this makes it possible to prevent the silicon layer 302 from being etched at the bottom of the hole H.

[0084] When the tungsten layer 303 is exposed at the bottom of the hole H in the etching target film 300, the tungsten layer 303 is removed. Fig. 8 is a diagram showing vapor pressure curves of WF5, WF6, and WOF4 versus temperature.

[0085] As shown in the vapor pressure curve, WF5, WF6, and WOF4 do not vaporize when the vapor pressure is lower than the vapor pressure defined by the curves of WF5, WF6, and WOF4 at a certain temperature, for example, below 40° C. If a material with a high underlayer selectivity, such as tungsten, is selected as the underlayer, the reaction product 304 of tungsten (see FIG. 4(b)) is unlikely to vaporize, and the reaction product 304 can ensure the underlayer selectivity even without supplying carbon radicals to the bottom of the hole H.

[0086] For example, under the above-mentioned set conditions (pressure in the process chamber=30 mT (4.0 Pa), substrate temperature≦40° C.), WF5 and WOF4 do not vaporize and are deposited on the tungsten-containing layer such as the tungsten layer 303. In the example of FIG. 4(b), a reaction product 304 containing tungsten is deposited on the top of the tungsten layer 303 and on the sidewall of the film 300 to be etched.

[0087] In this state, heat treatment (including radical ashing and plasma ashing) was performed. In FIG. 9(b), heat treatment was performed after low-temperature etching, and then hydrofluoric acid cleaning was performed. In this case, a tungsten-containing oxide film 306 was generated on the sidewalls of the etching target film 300, where the reaction product of tungsten was oxidized. It was found that the tungsten-containing oxide film 306 was changed into a substance that could not be removed by hydrofluoric acid cleaning by performing heat treatment before hydrofluoric acid cleaning.

[0088] In comparison, Fig. 9(a) shows the result when hydrofluoric acid cleaning (HF cleaning) was performed without heat treatment after low-temperature etching. In this case, no reaction product 304 containing tungsten is present on the sidewalls of the etching target film 300. In both cases, the hydrofluoric acid cleaning was performed after exposing the substrate W to the atmosphere.

[0089] From the above, it was found that the reaction product 304 containing tungsten became a stable tungsten-containing oxide film (WOx) during the heat treatment process, and became a film that could not be removed even by washing with hydrofluoric acid. Note that the reaction product 305 of ammonium silicofluoride generated during the etching process was removed by washing with hydrofluoric acid.

[0090] Furthermore, as shown in FIG. 9(b), after cleaning with hydrofluoric acid, the tungsten-containing oxide film 306 remained on the sidewall of the silicon oxide layer 300a, but did not remain on the sidewall of the silicon nitride layer 300b.

[0091] The reason why the tungsten-containing oxide film 306 is not present on the sidewall of the silicon nitride layer 300b is that the tungsten oxide film on the silicon nitride layer 300b adheres to the ammonium silicofluoride formed on the silicon nitride layer 300b. Therefore, it is considered that when the ammonium silicofluoride is peeled off by hydrofluoric acid during the hydrofluoric acid cleaning, the tungsten-containing oxide film 306 is also peeled off and removed. In addition, when oxygen gas is not used in the heat treatment, the reaction product 304 containing tungsten that adheres to the silicon nitride layer 300b is not oxidized. Therefore, when oxygen gas is not used in the heat treatment, the tungsten-containing oxide film 306 is not formed on the silicon nitride layer 300b.

[0092] On the other hand, the tungsten-containing oxide film 306 attached to the sidewall of the silicon oxide layer 300a is considered to be formed by the reaction between the silicon oxide layer 300a and the reaction product 304 containing tungsten during the heat treatment.

[0093] There are two possible sources of oxygen used when the tungsten reaction product 304 is oxidized to form the tungsten-containing oxide film 306. The first source is the silicon oxide layer 300a, and the second source is oxygen gas. That is, since the film to be etched 300 has a silicon-oxygen-containing film, for example the silicon oxide layer 300a, the oxygen O that oxidizes the tungsten reaction product may be supplied from the silicon-oxygen-containing film on which the tungsten-containing oxide film 306 is deposited. Alternatively, the oxygen O that oxidizes the tungsten reaction product may be supplied from the oxygen-containing gas by supplying the oxygen-containing gas into the processing vessel.

[0094] The above-described substrate processing and substrate temperature control for removing the tungsten-containing reaction product generated during low-temperature etching without forming a tungsten-containing oxide film 306 from the tungsten-containing reaction product will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a diagram showing the relationship between the ashing rate and the temperature of the substrate W when an ashing process is performed on an organic resist coating film as a substitute for the organic film mask 301 according to the embodiment. Fig. 11 is a diagram showing the presence or absence of residue on the substrate W after the substrate W according to the embodiment is subjected to a heat treatment.

[0095] 10 shows the ashing rate versus substrate temperature when the radical ashing process and the plasma ashing process are performed after the etching process based on the above-mentioned etching process conditions, radical ashing process conditions, and plasma ashing process conditions. It can be seen that the controlled substrate temperatures are different when the radical ashing process and the plasma ashing process are performed.

[0096] In the case of radical ashing, since it does not have ion energy, when the temperature is high, i.e., when the thermal energy is high, oxygen reacts with the organic film mask and vaporizes. Therefore, the ashing rate is highly temperature dependent, and the higher the temperature, the higher the ashing rate.

[0097] On the other hand, when the temperature is lowered, the ashing rate decreases, and at approximately 90° C. the ashing rate approaches 0. For this reason, the organic film mask cannot be completely removed at a substrate temperature lower than approximately 90° C. Therefore, in radical ashing, the substrate temperature is controlled to a temperature higher than approximately 90° C. at which the organic film mask can be completely removed.

[0098] FIG. 11 shows the presence or absence of tungsten-containing residues, the presence or absence of ammonium silicofluoride residues, and the presence or absence of CF polymer residues on the substrate W relative to the wafer temperature (substrate temperature) of the substrate W after the radical ashing process and the plasma ashing process are performed on the substrate W based on the above-mentioned etching process conditions, radical ashing process conditions, and plasma ashing process conditions.

[0099] In the case of radical ashing, when the wafer temperature is higher than 115°C, residues of tungsten-containing substances (W residues) are observed on the substrate W. This suggests that a stable tungsten oxide film is formed at temperatures of about 115°C or higher. Therefore, the substrate temperature during radical ashing is controlled to be lower than about 115°C. Therefore, in the case of radical ashing, in order to completely remove the organic film mask without forming a tungsten oxide film, it is preferable to control the substrate temperature to a range of about 90°C to about 115°C.

[0100] That is, a first reaction product containing a transition metal, for example tungsten, is generated in the etching process. When the first reaction product reacts with oxygen O to form a metal oxide, for example a tungsten oxide film, the heat treatment process sets the desired temperature (substrate temperature) of the substrate W to be lower than the first temperature. An example of the first temperature is about 115° C., at which a stable tungsten oxide film is formed. In addition, the first temperature is preferably lower than the temperature at which the etching target film 300 is deformed or altered by heat.

[0101] In the case of plasma ashing, ashing is performed by the energy of ions in addition to radicals, so that an ashing rate can be ensured even at a substrate temperature lower than that during radical ashing. However, when the wafer temperature is lower than 60°C, residues due to ammonium silicofluoride (AFS) are observed. The decomposition temperature of ammonium silicofluoride (AFS) is about 60°C. Therefore, in the case of plasma ashing, in order to remove ammonium silicofluoride without forming a tungsten oxide film, it is preferable to control the substrate temperature to a range of about 60°C to about 115°C.

[0102] That is, a second reaction product containing silicon Si, nitrogen N, and fluorine F, for example ammonium silicofluoride, is generated in the etching process. When the second temperature is equal to or higher than the temperature at which the second reaction product is thermally decomposed, the heat treatment process may set a desired temperature (substrate temperature) of the substrate W to equal to or higher than the second temperature to remove the second reaction product. An example of the second temperature is about 60° C., which is the decomposition temperature of ammonium silicofluoride (AFS). The second reaction product deposited on the film to be etched contains ammonium silicofluoride.

[0103] In the case of radical ashing, when the wafer temperature is lower than 90°C, CF polymer residues are observed. In the case of plasma ashing, there is no trend depending on the wafer temperature, and no CF polymer residues are observed. This coincides with the trend of the ashing rate. In other words, by setting the temperature at which the organic film mask can be removed, the CF polymer can also be removed. However, if the process conditions of the etching process change, the temperature at which the CF polymer can be removed in the ashing process also changes, so it is not limited to the temperature at which the CF polymer can be removed being the same as the temperature at which the organic film mask can be removed.

[0104] As explained above, in order to increase the ashing rate during ashing, it is desirable to control the substrate temperature as high as possible, but once a tungsten oxide film is formed, it cannot be removed even by washing with hydrofluoric acid. For this reason, the upper limit of the substrate W temperature must be controlled to about 115°C.

[0105] Next, since ammonium silicofluoride is likely to remain in low-temperature etching, it is preferable to control the lower limit of the substrate temperature to about 60° C. during plasma ashing in order to completely remove the ammonium silicofluoride.

[0106] Furthermore, in the case of radical ashing, in order to completely remove the organic film mask, it is preferable to control the lower limit of the substrate W temperature at the time of radical ashing to about 90°C.

[0107] [Variations] When the second temperature is set to a value equal to or higher than the temperature at which the second reaction product containing nitrogen N, hydrogen H, and halogens, which is generated in the etching process and deposited on the etching target film 300, is thermally decomposed, the heat treatment process may set the temperature of the substrate W to the second temperature or higher. This makes it possible to remove the second reaction product.

[0108] In addition, the temperature at which the CF polymer, which is a reaction product generated in the etching process, can be removed may be considered to be about 90° C., which is the same as the mask removal temperature. Therefore, by controlling the substrate temperature to about 90° C. or higher, the third reaction product, which is an example of the CF polymer and contains carbon C and fluorine F, can be removed. However, if the process conditions of the etching process change, the temperature at which the CF polymer can be removed in the ashing process also changes, so it is preferable to set the substrate temperature to a temperature at which the CF polymer can be removed.

[0109] In other words, when the third temperature is set to a value equal to or higher than the temperature at which the third reaction product such as CF polymer can be removed by the ashing process, the ashing process may be performed by setting the substrate temperature to the third temperature or higher to remove the third reaction product.

[0110] When the mask is an organic film, the ashing step may remove the organic film. The third temperature may be equal to or higher than a temperature at which the organic film becomes removable by the ashing step.

[0111] In the etching process, the substrate temperature may be set to a value lower than the temperature indicated by the vapor pressure curve of the transition metal halide.

[0112] Furthermore, not only when tungsten is used for the underlayer, but also when tungsten is used for the mask, the same effects as those described above can be obtained by setting the substrate temperature according to the radical ashing or plasma ashing shown in FIG. 10.

[0113] In the etching process, when the etching target film 300 contains silicon (Si), the etching target film 300 may be etched by plasma of a gas containing nitrogen (N), hydrogen (H), and fluorine (F).

[0114] In the etching process, when the etching target film 300 contains silicon nitride (SiN), the etching target film 300 may be etched by plasma of a gas containing hydrogen (H) and fluorine (F).

[0115] The etching step and the heat treatment step are performed without exposing the substrate W to the atmosphere. After the ammonium silicofluoride is removed in the heat treatment step, the substrate W may be exposed to the atmosphere. In other words, the substrate W may be exposed to the atmosphere in the ashing step and hydrofluoric acid cleaning performed after the heat treatment step.

[0116] In the case where the substrate processing apparatus performing the radical ashing process and the substrate processing apparatus performing the plasma ashing process are separate apparatuses, the lower limit value does not matter as long as the upper limit value of the substrate W temperature is controlled to about 115°C in the substrate processing apparatus performing the radical ashing process. This prevents the formation of a tungsten-containing oxide film and allows the reaction products of tungsten to be removed. Also, in the substrate processing apparatus performing the plasma ashing process, the upper limit value does not matter as long as the lower limit value of the substrate W temperature is controlled to about 60°C in order not to leave ammonium silicofluoride behind.

[0117] When the substrate processing apparatus performing the radical ashing process and the substrate processing apparatus performing the plasma ashing process are the same apparatus, the substrate temperature is controlled to a range of about 60°C to about 115°C.

[0118] In addition, when oxygen radical ashing or oxygen plasma ashing is performed on the etching shape such as hole H formed in the main etching process, the mask 301 on the etching target film 300 can be removed. The CD of the widest position (Bow CD) of the hole H in the etching target film 300 and the CD of the bottom of the hole H (BTM CD), measured after removing the mask 301, were almost unchanged before and after ashing. Therefore, the etching shape is not affected by oxygen radical ashing or oxygen plasma ashing.

[0119] In the substrate processing system 1, the etching process and the heat treatment are not limited to being performed on the same system (In-System), but may be performed in the same processing chamber (In-situ). The processing chamber in which the heat treatment is performed has a heater on the stage, and the stage is heated to a high temperature to heat-treat the substrate. The heat treatment may be performed in at least one of a processing chamber having a stage with a heater and a load lock chamber. The heat treatment may be performed in a vacuum transfer chamber 220 in which a heater is mounted on an arm of the transfer mechanism 21 that holds the substrate. The substrate W may also be heat-treated by radiant heat from a lamp or the like, infrared heating, or the like.

[0120] As described above, according to the substrate processing method and substrate processing apparatus of the present embodiment, reaction products containing transition metals deposited in the etching process can be removed.

[0121] The substrate processing method and substrate processing apparatus according to the presently disclosed embodiments should be considered as illustrative and not restrictive in all respects. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be configured in other ways without contradiction, and can be combined without contradiction.

[0122] The substrate processing apparatus of the present disclosure can be applied to any type of apparatus, including Atomic Layer Deposition (ALD) apparatus, Capacitively Coupled Plasma (CCP), Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP). [Explanation of symbols]

[0123] 1. Substrate Processing System 2,3 Substrate processing equipment 10 Processing vessel 101 Processing vessel 102 Top plate 103 Antenna Room 104 Processing Room 111 Ion Trap 130 Control section 211~214 Processing Room 220 Vacuum Transfer Chamber 231,232 Load lock chamber 240 Atmospheric Transport Chamber 251~253 Loading port 261~268 Gate valve 270 Control Unit 300 Film to be etched 300a silicon oxide layer 300b Silicon nitride layer 301 Mask 303 Tungsten layer 305 Reaction products of ammonium silicofluoride 306 Tungsten oxide film ST Stage

Claims

1. A step of preparing a substrate on which a laminated film is formed, the laminated film including at least a film to be etched, a base layer disposed below the film to be etched, and a mask disposed above the film to be etched; Etching the film to be etched through the mask with plasma; After the etching step, heat treating the substrate at a desired temperature; After the heat treatment step, the substrate is washed with hydrofluoric acid; having At least one of the mask and the underlayer contains a transition metal; When a value lower than a temperature at which a first reaction product containing the transition metal, which is generated in the etching step and deposited on at least one of the etching target film and the mask, reacts with oxygen O to form a metal oxide, is set to a first temperature, The heat treatment step includes setting a desired temperature of the substrate lower than the first temperature. A method for processing a substrate.

2. The desired temperature of the substrate in the heat treatment step is lower than 115°C. The method of claim 1 .

3. When a value equal to or higher than a temperature at which a second reaction product containing silicon Si, nitrogen N, and fluorine F, which is generated in the etching step and deposited on the etching target film, is thermally decomposed, The heat treatment step includes setting a desired temperature of the substrate to be equal to or higher than the second temperature, and removing the second reaction product. The substrate processing method according to claim 1 .

4. the second reaction product deposited on the film to be etched includes ammonium silicofluoride; The substrate processing method according to claim 3 .

5. The etching step includes: When the film to be etched contains silicon (Si), the film to be etched is etched using plasma of a gas containing nitrogen (N), hydrogen (H), and fluorine (F); The substrate processing method according to any one of claims 1 to 4.

6. The etching step includes: When the film to be etched contains silicon nitride (SiN), the film to be etched is etched using plasma of a gas containing hydrogen (H) and fluorine (F); The substrate processing method according to any one of claims 1 to 5.

7. When a value equal to or higher than a temperature at which a second reaction product containing nitrogen N, hydrogen H, and a halogen, which is generated in the etching step and deposited on the etching target film, is thermally decomposed, the second temperature is set to a value equal to or higher than a temperature at which the second reaction product containing nitrogen N, hydrogen H, and a halogen, which is generated in the etching step and deposited on the etching target film, The heat treatment step includes setting a desired temperature of the substrate to be equal to or higher than the second temperature, and removing the second reaction product. The substrate processing method according to claim 1 .

8. the second reaction product that deposits on the film to be etched is an ammonium halide; The substrate processing method according to claim 7 .

9. The second reaction product deposited on the film to be etched contains at least one of ammonium, ammonium chloride, ammonium bromide, and ammonium iodide generated in the etching step. The substrate processing method according to claim 7 or 8.

10. The etching target film includes a silicon-oxygen-containing film, The oxygen O is supplied from the silicon-oxygen-containing film of the etching target film on which the first reaction product is deposited. The substrate processing method according to claim 2 .

11. supplying an oxygen-containing gas into a processing vessel in which the substrate is prepared; The oxygen O is supplied from the oxygen-containing gas. The substrate processing method according to claim 2 or 10.

12. The heat treatment step includes ashing the substrate using plasma. The substrate processing method according to any one of claims 1 to 11.

13. The ashing step removes a third reaction product containing carbon C and fluorine F produced in the etching step. The method of claim 12.

14. When a third temperature is set to a value equal to or higher than a temperature at which the third reaction product can be removed by the ashing step, The ashing step includes setting a desired temperature of the substrate to a third temperature or higher, and removing the third reaction product. The method of claim 13.

15. the third temperature is equal to or higher than a temperature at which the organic film can be removed by the ashing step; The method of claim 14.

16. When the mask is an organic film, the ashing step removes the organic film. The substrate processing method according to any one of claims 12 to 15.

17. The first temperature is lower than a temperature at which the film to be etched is deformed or altered by heat. The substrate processing method according to claim 2 , 10 , or 11 .

18. The etching step and the heat treatment step include is performed without exposing the substrate to atmosphere. The substrate processing method according to any one of claims 1 to 17.

19. The etching step includes: setting the desired temperature of the substrate to a value lower than the temperature indicated by the vapor pressure curve of the transition metal halide; The substrate processing method according to any one of claims 1 to 18.

20. The transition metal is tungsten (W). The substrate processing method according to any one of claims 1 to 19.

21. A substrate processing apparatus having a processing vessel, a stage on which a substrate is placed, and a control unit, The control unit is A step of preparing a substrate on which a laminated film is formed, the laminated film including at least a film to be etched, a base layer disposed below the film to be etched, and a mask disposed above the film to be etched; Etching the film to be etched through the mask with plasma; After the etching step, heat treating the substrate at a desired temperature; After the heat treatment step, the substrate is washed with hydrofluoric acid; Control the At least one of the mask and the underlayer contains a transition metal; When a value lower than a temperature at which a first reaction product containing the transition metal, which is generated in the etching step and deposited on at least one of the etching target film and the mask, reacts with oxygen O to form a metal oxide, is set to a first temperature, The heat treatment step includes setting a desired temperature of the substrate lower than the first temperature. Substrate processing equipment.

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