Etching method and plasma etching apparatus

Abstract

To improve the etching rate by supplying a bottom part of an etched shape formed on a substrate having a carbon-containing film with an etchant efficiently.SOLUTION: An etching method includes the steps for (a) providing a substrate having a carbon-containing film on a substrate support part and (b) etching the substrate with plasma generated from a gas including H and O to form an etched shape having a bottom part on the carbon-containing film. The temperature of the substrate support part is adjusted to 0°C or less in step (b).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an etching method and a plasma etching apparatus. [Background technology]

[0002] Patent Document 1 describes a technique for performing plasma etching to form a recess with a high aspect ratio in a silicon oxide film as an etching target film. In this technique, a silicon oxide film is etched by generating plasma of a process gas containing a fluorine-containing gas, such as a fluorocarbon gas or a hydrofluorocarbon gas, and hydrogen gas. In a high aspect structure such as a contact hole in a memory device, the aspect ratio increases as etching progresses, and the amount of etchant supplied decreases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-122774 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for efficiently supplying an etchant to the bottom of an etching shape (concave portion) formed in a substrate having a carbon-containing film, thereby improving the etching rate. [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: (a) providing a substrate having a carbon-containing film on a substrate support; (b) etching the substrate with a plasma generated from a gas containing H and O to form an etched feature having a bottom in the carbon-containing film; (c) selectively depositing H at the bottom of the etched feature by a plasma generated from a gas containing H and O; 2 forming a condensed or solidified layer of O;and in the step (b), adjusting the temperature of the substrate support to 0° C. or lower. Effect of the Invention

[0006] According to one aspect, an etchant can be efficiently supplied to the bottom of an etching shape formed on a substrate having a carbon-containing film, thereby improving the etching rate. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a plasma processing system according to an embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an example of a plasma etching apparatus according to an embodiment. [Diagram 3] FIG. 3 is a flowchart showing the etching method according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between the temperature of the substrate support part and H2O adsorption by H2O gas. [Diagram 5] FIG. 5 is a diagram showing the relationship between the temperature of the substrate supporting part and the etching rate by H2O gas. [Figure 6] FIG. 6 is a diagram showing the relationship between the temperature of the substrate support part and H2O adsorption by O2 gas. [Figure 7] FIG. 7 is a diagram showing the relationship between the temperature of the substrate support part and the etching rate by O 2 gas. [Figure 8] FIG. 8 is a flowchart showing the etching method according to the second embodiment. [Figure 9] FIG. 9 is a diagram for explaining the flow of etching of the etching target film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In one exemplary embodiment, a method for etching a carbon-containing film is provided, the method comprising the steps of (a) providing a substrate having a carbon-containing film on a substrate support, and (b) etching the substrate with plasma generated from a gas containing H and O to form an etched feature having a bottom in the carbon-containing film, wherein the temperature of the substrate support is adjusted to 0° C. or lower in the step (b). According to this embodiment, an etchant can be efficiently supplied to the bottom of the etched feature, thereby increasing the etching rate.

[0009] In one exemplary embodiment, the method may include (c) selectively forming a condensed or solidified layer of HO at the bottom of the etched feature using a plasma generated from a gas containing H and O.

[0010] In one exemplary embodiment, steps (b) and (c) may be performed simultaneously.

[0011] In one exemplary embodiment, step (c) may be performed with an opening diameter of the etched shape of 200 nm or less and an aspect ratio of 3 or more.

[0012] Etching may be progressed by attracting ions in the plasma to the bottom portion and causing the condensed or solidified layer formed on the bottom portion to react with the bottom portion.

[0013] In one exemplary embodiment, after step (a), the temperature of the substrate support may be set to −30° C. or lower.

[0014] In one exemplary embodiment, the method includes a step (d) of supplying bias power to the substrate support and etching the bottom with the generated plasma, and the temperature of the substrate support may be adjusted to 0°C or lower in steps (b) to (d).

[0015] In one exemplary embodiment, etching may be carried out by attracting ions in the plasma to the bottom portion and reacting with a liquid condensed layer or a solid coagulated layer formed on the bottom portion.

[0016] The bias voltage may be pulsed. The bias voltage may be a negative DC bias.

[0017] In one exemplary embodiment, a plasma etching apparatus is provided, the plasma etching apparatus including a chamber, a substrate support disposed in the chamber and supporting a substrate, a plasma generating unit for generating plasma in the chamber, and a controller, the controller of the apparatus executing the steps of (a) providing a substrate having a carbon-containing film on the substrate support, and (b) etching the substrate with plasma generated from a gas containing H and O to form an etching shape having a bottom in the carbon-containing film, and adjusting the temperature of the substrate support to 0° C. or lower in the step (b).

[0018] 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.

[0019] [Plasma processing system] In one embodiment, the plasma processing system shown in FIG. 1 includes a plasma etching apparatus 1 and a controller 2. The plasma etching apparatus 1 includes a plasma processing chamber 10 (hereinafter also referred to as "chamber 10"), a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 described later, and the gas exhaust port is connected to an exhaust system 40 described later. The substrate support 11 is disposed in the plasma processing space, and has a substrate support surface for supporting a substrate.

[0020] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR plasma), a helicon wave plasma (HWP), a surface wave plasma (SWP), or the like. Also, various types of plasma generating units may be used, including an alternating current (AC) plasma generating unit and a direct current (DC) plasma generating unit. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100 kHz to 10 GHz. Thus, the AC signal includes a radio frequency (RF) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 200 kHz to 150 MHz.

[0021] The controller 2 processes computer-executable instructions that cause the plasma etching apparatus 1 to perform various steps described in this disclosure. The controller 2 may be configured to control each element of the plasma etching apparatus 1 to perform various steps described herein. In one embodiment, a part or all of the controller 2 may be included in the plasma etching apparatus 1. The controller 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processor (CPU: Central Processing Unit) 2a1, a memory unit 2a2, and a communication interface 2a3. The processor 2a1 may be configured to perform various control operations based on programs and recipes stored in the memory unit 2a2. The memory unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma etching apparatus 1 via a communication line such as a local area network (LAN).

[0022] Next, a configuration example of a capacitively coupled plasma etching apparatus 1 will be described as an example of the plasma etching apparatus 1 with reference to FIG. 2. The plasma etching apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma etching apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a shower head 13. The substrate support 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support 11. In one embodiment, the shower head 13 constitutes at least a part of a ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The sidewall 10a is grounded. The shower head 13 and the substrate support 11 are electrically insulated from the plasma processing chamber 10 housing.

[0023] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region (substrate support surface) 111a for supporting a substrate (wafer) W, and an annular region (ring support surface) 111b for supporting the ring assembly 112. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. In one embodiment, the main body 111 includes a base and an electrostatic chuck, and holds the substrate W by electrostatic force. The base includes a conductive member. The conductive member of the base functions as a lower electrode. The electrostatic chuck is disposed on the base. The upper surface of the electrostatic chuck has a substrate support surface 111a. The ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. Although not shown, the substrate support 11 may include a temperature adjustment module configured to adjust at least one of the electrostatic chuck, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A flow path 18 is formed in the substrate support 11. A heat transfer fluid such as brine or gas flows through the flow path 18. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a. For example, a heat transfer gas is supplied between the back surface of the substrate W and the substrate support surface 111a from a heat transfer gas pipe 19 penetrating the substrate support 11.

[0024] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes a conductive member. The conductive member of the shower head 13 functions as an upper electrode. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0025] The gas supply 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include at least one flow modulation device to modulate or pulse a flow rate of the at least one process gas.

[0026] The power source 30 includes an RF power source 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to a conductive member of the substrate support 11 and / or a conductive member of the showerhead 13. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power source 31 can function as at least a part of the plasma generating unit 12. In addition, by supplying a bias RF signal to the conductive member of the substrate support 11, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

[0027] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to the conductive member of the substrate support 11 and / or the conductive member of the shower head 13 via at least one impedance matching circuit, and is configured to generate a source RF signal (HF power) for plasma generation. The HF power is a high-frequency power for plasma generation that mainly contributes to plasma generation. In one embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to the conductive member of the substrate support 11 and / or the conductive member of the shower head 13. The second RF generating unit 31b is coupled to the conductive member of the substrate support 11 via at least one impedance matching circuit, and is configured to generate a bias RF signal (LF power, bias power). The LF power is a high-frequency power for bias that mainly contributes to attracting ions to the substrate W. In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 200 kHz to 13.56 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are provided to the conductive member of the substrate support 11. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0028] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to a conductive member of the substrate support 11 and configured to generate a first DC signal. The generated first DC signal is applied to the conductive member of the substrate support 11. In one embodiment, the first DC signal may be applied to another electrode, such as an electrode in an electrostatic chuck. In one embodiment, the second DC generator 32b is connected to a conductive member of the showerhead 13 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the showerhead 13. In various embodiments, the first and second DC signals may be pulsed. The pulsed first and second DC signals may be negative polarity DC biases. The first and second DC generating units 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided in place of the second RF generating unit 31b.

[0029] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0030] Here, the substrate W to be processed is a wafer having a diameter of 300 mm. The surface temperature of the substrate W may be controlled by measuring it with a temperature sensor attached to the surface of the substrate W via an adhesive such as silicone gel. The surface temperature may be calculated from the temperature difference between each part of the substrate support part 11, or the substrate temperature may be measured by an optical method. In this specification, a mixed gas refers to a gas (etching gas) in which two or more types of gases are mixed.

[0031] First Embodiment [Etching method] In the first embodiment, a method MT1 for etching a substrate will be described with reference to Fig. 3. Hereinafter, the method MT1 will be described taking as an example a case where the method MT1 is applied to a substrate W using a plasma etching apparatus 1. The method MT1 includes steps S1 to S11.

[0032] 2, in step S1, a substrate W including a carbon-containing film is supported by a substrate support 11 in a chamber 10. The carbon-containing film functions as a mask for a film to be etched, which serves as an underlying film.

[0033] 9(a), for example, a silicon-containing film is used as a base film 53 on a substrate 54, and a carbon-containing film 51 thereon is etched. The carbon-containing film 51 is etched in the pattern of the openings of the film 50 on the carbon-containing film 51, thereby forming an etched shape (recess) such as a hole H in the carbon-containing film 51. The film 50 may be a silicon-containing film or a metal-containing film.

[0034] The carbon-containing film 51 may be a carbon film, an amorphous carbon film, or SOC (Spin On Carbon). The undercoat film 53 may be a silicon-containing film such as a silicon oxide film (SiO2), and may include two or more types of silicon-containing films. The two or more types of silicon-containing films may include a laminated film of a silicon oxide film and a polysilicon film, or a laminated film of a silicon oxide film and a silicon nitride film. In this embodiment, for example, in memory devices such as 3D-NAND, etching of a silicon-containing film having an aspect ratio of 3 or more is performed. At that time, the carbon-containing film 51 is used as a mask material, and the etching method MT1 according to this embodiment is effective for etching the carbon-containing film 51.

[0035] In FIG. 3, next, in step S3, the temperature of the substrate support 11 is set to, for example, −30° C. or less before the start of etching (the temperature of the substrate before the start of etching is substantially the same as the temperature of the substrate support 11 before the start of etching). The temperature of the substrate support may be, for example, 0° C. or less. By setting the temperature of the substrate support to a low temperature, for example, −30° C. or less, the supply of the etchant to the bottom of the etching shape is promoted, and the etching rate can be improved. The temperature of the substrate support may be controlled by cooling the substrate support 11 using a cooler, or by passing a coolant such as liquid nitrogen or fluorocarbons through the substrate support 11 to cool the substrate support 11. The temperature of the substrate may be adjusted in this way. In consideration of the heat input by the plasma, the temperature of the coolant passing through the substrate support 11 during etching is set to a temperature 10° C. to 50° C. lower than the target temperature of the substrate. In one example, a coolant of −100° C. to −10° C. is supplied to the flow path 18 in the substrate support 11. The target temperature of the substrate may be set in advance to any temperature of 0° C. or less. Also, a heat transfer gas may be supplied between the electrostatic chuck 5 and the back surface of the substrate W held thereon from a heat transfer gas pipe 19 penetrating the substrate support portion 11. By controlling the pressure of the heat transfer gas supplied between the electrostatic chuck 5 and the back surface of the substrate W, it is possible to control the thermal conduction and thereby adjust the temperature of the substrate. An inert gas may be used as the heat transfer gas. As an example, a rare gas, for example, helium gas, may be used.

[0036] Next, in step S5, H2O gas obtained by gasifying H2O is supplied from the gas supply unit 20 into the plasma processing chamber 10 as an etching gas. However, the etching gas is not limited to H2O, and may be any gas containing H and O. The gas containing H and O may be H2O2 gas or a mixed gas of H2 gas and O2 gas. The etching gas may be a mixed gas of two or more types of gas containing H2O and / or H2O2.

[0037] In step S7, the substrate W is etched. In step S7, for example, high frequency power for plasma generation of 27 MHz to 100 MHz is supplied from the first RF generating unit 31a to the shower head 13 (upper electrode) to etch the carbon-containing film 51 with the plasma of H2O gas. High frequency power for plasma generation may be supplied from the first RF generating unit 31a to the substrate support unit 11 (lower electrode). The mixed gas may be prepared by supplying two or more types of gases to the chamber 10 and mixing them in the chamber 10, or may be mixed before being supplied to the chamber 10. The frequency of the high frequency supplied from the first RF generating unit 31a may be 0.1 kW to 5 kW, for example. In the present disclosure, H2O gas is supplied, and the carbon-containing film 51 is etched with the plasma of H2O gas.

[0038] The etching process of the carbon-containing film 51 in step S7 includes the following two steps. These two steps (the first and second steps described below) may be performed simultaneously or separately. Only one of the two steps is not performed. In the first step, a condensed or solidified layer of H2O is selectively formed at the bottom of the etched shape formed in the carbon-containing film 51. This condensed or solidified layer is formed by preferentially physically adsorbing H2O, which functions as an etchant, to the bottom of the etched shape. Physical adsorption of H2O occurs by lowering the temperature of the substrate support (for example, 0° C. or lower). The adsorption of H2O to the bottom forms a condensed or solidified layer of H2O.

[0039] Examples of a method for adjusting the substrate support to a low temperature (e.g., 0° C. or lower) include controlling the pressure of the heat transfer gas supplied between the substrate W and the electrostatic chuck 5 during etching and / or controlling the magnitude of the bias power. This allows the flow rate of the HO gas to be adjusted to selectively form a liquid-phase condensed layer or a solid-phase solidified layer in which HO is condensed at the bottom of the etched shape.

[0040] In the second step, a bias power of 200 kHz to 13.56 MHz is supplied from the second RF generating unit 31b to the substrate support unit 11 to promote etching with plasma of H2O gas. The magnitude of the bias power may be 500 W or more. The bias power is not limited to high-frequency power, and may be a voltage pulse such as a DC pulse. The bias power draws ions in the plasma to the bottom of the etching shape, and the condensed or solidified layer formed at the bottom reacts with the bottom to advance the etching. As a result, an etching shape having a bottom is formed in the carbon-containing film.

[0041] The step of etching the substrate with plasma generated from HO gas to form an etched shape having a bottom in the carbon-containing film 51 and the step of selectively forming a condensed or solidified layer of HO at the bottom of the etched shape with plasma generated from HO gas may be performed simultaneously.

[0042] During etching, the temperature of the substrate rises due to heat input from the plasma. However, in the present disclosure, after the substrate W is provided on the substrate support 11, the temperature of the substrate support is adjusted to 0° C. or lower in the process of etching the substrate with plasma generated from HO gas and the process of reacting the condensed or solidified layer formed at the bottom of the etched shape with the bottom.

[0043] Next, in step S9, it is determined whether to terminate the etching of the carbon-containing film 51. The etching in step S7 is performed until it is determined in step S9 that the etching of the carbon-containing film 51 is terminated. When it is determined in step S9 that the etching of the carbon-containing film 51 is terminated, the substrate W is unloaded from the plasma processing chamber 10 in step S11, and this process is terminated.

[0044] [H2O adsorption] The temperature of the substrate support part and the adsorption of H2O to the bottom of the etched shape due to the supply of H2O gas will be described with reference to Fig. 4. Fig. 4 is a diagram showing the relationship between the temperature of the substrate support part and the adsorption of H2O due to H2O gas. The horizontal axis of Fig. 4 indicates the temperature of the substrate support part, and the vertical axis indicates the amount of H2O adsorbed to the substrate surface. The amount of H2O adsorption is calculated from the amount of H2O exhausted measured using a quadrupole mass spectrometer (QMS).

[0045] 5, the horizontal axis represents the temperature of the substrate support part, and the vertical axis represents the etching rate. The etching rate on the vertical axis is normalized by setting the etching rate when the temperature of the substrate support part is −70° C. as 1.

[0046] As a result, as shown in Fig. 4 and Fig. 5, when the temperature of the substrate support part is 0°C or less, the lower the temperature of the substrate support part, the more H2O gas is adsorbed to the substrate, and the etching rate significantly increases at -30°C or less. From the above, it is considered that when the temperature of the substrate support part is 0°C or less, H2O is adsorbed to the bottom of the etched shape formed in the carbon-containing film, and a condensed or solidified layer of H2O is formed. The increase in the etching rate due to the adsorption of H2O is remarkable when the temperature of the substrate support part is -30°C or less, but the temperature of the substrate support part needs to be 0°C or less, and does not have to be the etching start temperature. This indicates that the amount of etchant increases as the amount of H2O adsorbed to the bottom of the etched shape of the carbon-containing film increases, and the etching rate increases. In other words, it is considered that the condensed or solidified layer of H2O formed at the bottom of the etched shape reacts with the bottom, and etching proceeds mainly by oxygen atoms in H2O, and by-products such as CO generated at that time are volatilized.

[0047] There is a correlation between the increase in the amount of H2O adsorbed to the bottom of the etched shape and the etching rate of the carbon-containing film, and the etching rate of the carbon-containing film increases as the amount of H2O adsorbed increases. However, if the amount of H2O adsorbed to the bottom of the etched shape of the carbon-containing film increases too much, the surface of the etched shape of the carbon-containing film is completely covered with H2O, and the ions in the plasma cannot reach the carbon-containing film, so the etching rate decreases. Therefore, as shown in Figure 5, the temperature of the substrate support is preferably -80°C or higher at which the surface of the etched shape is not completely covered with H2O.

[0048] In addition, when the carbon-containing film contains H, O2 gas may be supplied instead of H2O gas. The temperature of the substrate support part and the adsorption of H2O to the bottom in this case will be described with reference to Figures 6 and 7. The horizontal axis of Figure 6 indicates the temperature of the substrate support part, and the vertical axis indicates the amount of H2O adsorbed to the substrate surface. The amount of H2O adsorbed is calculated from the amount of H2O exhausted measured by a quadrupole mass spectrometer. The horizontal axis of Figure 7 indicates the temperature of the substrate support part, and the vertical axis indicates the etching rate. The etching rate on the vertical axis is normalized by setting the etching rate when the temperature of the substrate support part is -70°C as 1.

[0049] As a result, as shown in Figures 6 and 7, when the temperature of the substrate support part is 0°C or less, the lower the temperature of the substrate support part, the more H2O gas is adsorbed to the substrate, and the etching rate significantly increases at -30°C or less. From the above, it is considered that when the temperature of the substrate support part is 0°C or less, the O2 gas plasma reacts with H in the carbon-containing film, and H2O is adsorbed to the bottom of the etching shape formed in the carbon-containing film, forming a condensed or solidified layer of H2O. The increase in the etching rate due to the adsorption of H2O is significant when the temperature of the substrate support part is -30°C or less, but the temperature of the substrate support part only needs to be 0°C or less, and does not have to be the etching start temperature.

[0050] In the etching method according to the first embodiment and the second embodiment described below, the carbon-containing film may be etched while increasing the temperature of the substrate (or the substrate support table). For example, etching may be started by setting the temperature of the substrate support to -70°C, and etching may be performed while increasing the temperature of the substrate support during etching. In this case, the temperature of the substrate support may be increased during etching of the carbon-containing film, or may be increased after etching. In this case, the temperature of the substrate support is also adjusted to 0°C or lower during etching.

[0051] During etching, the temperature of the substrate rises due to heat input from the plasma, but the temperature of the substrate is controlled by adjusting the pressure of the heat transfer gas supplied between the back surface of the substrate and the front surface of the substrate support part, and the temperature of the substrate support part is adjusted to 0° C. or less even during etching. In other words, the temperature of the substrate support part is adjusted to 0° C. or less during the process of supplying an etching gas containing hydrogen fluoride gas into the chamber 10, and the process of supplying high-frequency power for plasma generation and etching the substrate W with the plasma generated from the etching gas.

[0052] <Second embodiment> [Etching method] In the second embodiment, a method MT2 for etching a substrate will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a flowchart showing the etching method according to the second embodiment. Fig. 9 is a diagram for explaining the flow of etching a film to be etched.

[0053] The method MT2 will be described below by taking as an example a case where the method MT2 is applied to a substrate W using a plasma etching apparatus 1. In the method MT2, the same steps as those in the method MT1 are given the same numbers and their descriptions will be omitted. The method MT2 includes the same steps S1 to S11 as the method MT1, and further includes steps S19, S71, and S72 between steps S7 and S9.

[0054] In method MT2, steps S1 to S7 are performed in the same manner as in method MT1, and then in step S19, the etched shape reaches a predetermined opening diameter or less and a predetermined aspect ratio or more, for example, the opening diameter of the etched shape is 200 nm or less and the aspect ratio is 3 or more, and then the flow rate of H2O gas is adjusted to selectively form a liquid condensed layer or a solid coagulated layer in which H2O is condensed at the bottom of the etched shape. This condensed layer or coagulated layer is formed by preferentially physically adsorbing H2O, which functions as an etchant, at the bottom of the etched shape. According to method MT2, even after etching has progressed to a depth where the aspect ratio is a predetermined value or more, for example, an aspect ratio of 3 or more, the condensed layer or coagulated layer can maintain or improve the etching rate.

[0055] 9(a) shows etching of a hole H at an etching depth A1 having an aspect ratio less than a predetermined aspect ratio, for example, an aspect ratio less than 3 (etching in step S7). The hole H is an example of an etching shape formed in the carbon-containing film 51, and the etching shape may be a line pattern.

[0056] 9(b) shows the etching of hole H at an etching depth A2 (>A1) with an aspect ratio of 3 or more (forming a condensed layer etc. in step S71 and etching in S72). In this etching, hole H becomes deeper, and a condensation phenomenon or solidification phenomenon occurs. By utilizing this, an etchant of HO gas is efficiently supplied to the bottom of the etched shape, and a condensed layer or solidification layer 52 of HO is selectively formed at the bottom of the etched shape.

[0057] In step S72, if the flow rate of the HO gas is too high, the amount of HO adsorbed to the bottom increases too much, the surface of the etched shape of the carbon-containing film is completely covered with HO, and the ions in the plasma do not reach the carbon-containing film, which reduces the etching rate. Therefore, by controlling the flow rate of the HO gas to a predetermined value and controlling the temperature of the substrate support to 0°C or lower, a condensed or solidified layer of HO is selectively formed at the bottom of the etched shape by the condensation or solidification phenomenon, and etching is promoted.

[0058] 8, in step S72, bias power is supplied to the substrate support 11 to cause ions in the plasma of the generated H2O gas to reach the bottom of the etching shape. Then, the energy of the ions causes a condensed or solidified layer 52 of H2O to react with the carbon-containing film, accelerating the etching of the carbon-containing film 51. As a result, anisotropic etching is performed on the carbon-containing film 51, as shown in FIG. 9(b).

[0059] Particularly in step S72, bias power is applied to the substrate support 11 to control the ions to reach the condensed or solidified layer 52. This promotes etching by the condensed or solidified layer 52 functioning as an etchant, thereby improving the etching rate.

[0060] In step S9 shown in Fig. 8, it is determined whether etching of the carbon-containing film 51 has been completed. For example, as shown in Fig. 9(c), it may be determined that etching has been completed when the base film 53 of the carbon-containing film 51 is exposed. For example, whether the base film 53 is exposed can be determined using an end point detection technique. However, the method of determining whether etching has been completed is not limited to this.

[0061] If it is determined in step S9 that the etching of the carbon-containing film is not completed, the process returns to step S71, and steps S71 and S72 are repeated. While steps S71 and S72 are repeated, the temperature of the substrate support is adjusted to 0° C. or less. If it is determined in step S9 that the etching is completed, the method MT2 is terminated.

[0062] In the method MT2 described above, step S71 of forming the condensed or solidified layer 52 and step S72 of etching with plasma of H2O gas are described as different steps, but they may be performed simultaneously. Steps S71 and S72 may be repeated. This is not limited to the case where steps S71 and S72 are repeatedly performed in order, but also includes the case where a process of forming the condensed or solidified layer 52 and etching with plasma of H2O gas are performed simultaneously. Performing them simultaneously improves the throughput of etching.

[0063] As a matter applicable to both the above-described method MT1 and method MT2, the gas containing H and O used for etching may contain a rare gas. Examples of the rare gas include argon gas and helium gas. In etching, the rare gas contributes to the promotion of etching by the action of ions (e.g., argon ions) in the plasma. That is, in etching, bias power is supplied to the substrate support 11, and the rare gas ions in the plasma are attracted to the bottom of the etched shape. This allows the condensed or solidified layer 52 formed at the bottom of the etched shape to react with the bottom of the etched shape by the energy of the ions, and allows the etching to proceed. However, it is not only the rare gas ions that impart energy to the condensed or solidified layer 52 and contribute to the promotion of etching. Various ions in the plasma of the gas containing the rare gas, H, and O are attracted to the substrate W, and energy is imparted to the condensed or solidified layer 52, allowing the etching to proceed. Note that the gas used for etching in steps S7 and S72 may contain a rare gas, and the plasma is generated stably. Furthermore, the gas used for etching in steps S71 and S72 may contain a gas containing C, S, P, or Si as a gas for correcting the shape.

[0064] In step S71 of method MT2, a gas containing H and O, such as HO gas, is supplied to form the condensed layer or solidified layer 52, and in step S72, the gas type is switched from the gas containing H and O to a rare gas, the rare gas is supplied to perform etching, and steps S71 and S72 may be repeated. However, a rare gas may be included in the gas containing H and O, and steps S71 and S72 may be performed using the same gas type.

[0065] [Example] An example of process conditions for each step in the methods MT1 and MT2 according to the embodiment is shown below. <Etching in step S7 in FIG. 3> Target film Carbon-containing film HF power: 0.1kW~5kW, 27MHz~100MHz LF power: 500W or more, 200kHz~13.56MHz Gas: Gas containing H and O (e.g., HO gas) Temperature of the substrate support part: 0℃ or less Pressure in the space between the back surface of the substrate and the electrostatic chuck: 10~200 Torr <Etching in step S7 of FIG. 8> Target film Carbon-containing film (aspect ratio less than 3) HF power: 0.1kW~5kW, 27MHz~100MHz LF power: 500W or more, 200kHz~13.56MHz Gas: Gas containing H and O (e.g., HO gas) Temperature of the substrate support part: 0℃ or less Pressure in the space between the back surface of the substrate and the electrostatic chuck: 10~200 Torr <Etching in steps S71 and S72 in FIG. 8> Target film Carbon-containing film (aspect ratio 3 or more) (Condensation layer formation step (S71 in FIG. 8) and etching step (S72 in FIG. 8)) HF power: 0.1kW~5kW, 27MHz~100MHz LF power: 500W or more, 200kHz~13.56MHz Gas: Gas containing H and O (e.g., HO gas) Temperature of the substrate support part: 0℃ or less Pressure in the space between the back surface of the substrate and the electrostatic chuck: 10~200 Torr As described above, according to the etching method of the present embodiment, etching can be accelerated.

[0066] 8 may not be performed. For example, when preparing a substrate W having a recess of a first depth formed in a carbon-containing film (step S1), steps S7 and S19 may not be performed if the recess of the first depth is already formed in the substrate W, or the recess of the first depth is formed by etching. The recess of the first depth means a depth at which a condensed layer and / or a solidified layer can be formed, and steps S7 and S19 can be omitted by providing a substrate having a recess of that depth formed.

[0067] The disclosed embodiment further includes the following aspects (A1) and (A2). (A1) An etching method comprising the steps of: (a) providing a substrate having a carbon-containing film, the carbon-containing film having a recess having a first depth defined by a bottom and sidewalls; (b) supplying a gas containing H and O to selectively form a condensed or solidified layer of HO at the bottom; (c) applying a bias power to the substrate support and etching the bottom surface with a plasma to form a recess having a second depth that is deeper than the first depth; The etching method, wherein in the steps (b) and (c), the temperature of the substrate support is adjusted to 0° C. or lower. (A2) An etching method comprising the steps of: (a) providing a substrate having a carbon-containing film and a mask on the carbon-containing film, the carbon-containing film having a recess having a first depth defined by a bottom and sidewalls; (b) supplying a gas containing H and O to selectively form a condensed or solidified layer of HO at the bottom; (c) applying a bias power to the substrate support and etching the bottom surface with a plasma to form a recess having a second depth that is deeper than the first depth; An etching method, wherein in the steps (b) and (c), the temperature of the substrate support part is adjusted to 0° C. or lower. (A3) The etching method according to (A2), wherein an aspect ratio calculated by combining the recess of the substrate and the mask in the providing step is 3 or greater. (A4) The etching method according to any one of (A1) to (A3), wherein in the step of forming the condensed layer or the solidified layer, plasma is formed from H2O.

[0068] The recess of the first depth has an aspect ratio shown in A1 of FIG. 9(a) smaller than a predetermined value, and in one example, the aspect ratio is smaller than 3. The recess of the second depth has an aspect ratio shown in A2 of FIG. 9(b) equal to or greater than a predetermined value, and in one example, the aspect ratio is equal to or greater than 3. The recess of the second depth may have an aspect ratio equal to or greater than a predetermined value and an opening diameter equal to or smaller than a predetermined value. The recess of the second depth may have an aspect ratio equal to or greater than 3 and an opening diameter equal to or smaller than 200 nm, in one example.

[0069] The etching method and plasma etching apparatus according to the presently disclosed embodiment should be considered as illustrative and not restrictive in all respects. The above-described embodiment can be modified and improved in various forms without departing from the scope and spirit of the appended claims. The matters described in the above-described embodiments can be configured in other ways without contradiction, and can be combined without contradiction. [Explanation of symbols]

[0070] 1. Plasma Etching Equipment 2. Control section 2a Computer 2a1 Processing section 2a2 Storage section 2a3 Communication Interface 10 Plasma Processing Chamber 11 Substrate support 13. Shower Head 21 Gas Source 20 Gas supply section 30 power supply 31 RF power supply 31a First RF generation unit 31b Second RF generation unit 32a First DC generation unit 32b Second DC generation section 40 Exhaust system 111 Main body 112 Ring Assembly

Claims

1. (a) providing a substrate having a carbon-containing film on a substrate support; (b) etching the substrate with plasma generated from a gas containing H and O to form an etched shape having a bottom in the carbon-containing film; (c) selectively forming a condensed or solidified layer of H2O at the bottom of the etched shape by plasma generated from a gas containing H and O; In the step (b), the temperature of the substrate support is adjusted to 0° C. or less. Etching method.

2. The step (b) and the step (c) are carried out simultaneously. The etching method according to claim 1 .

3. The step (c) is performed in such a manner that the opening diameter of the etched shape is 200 nm or less and the aspect ratio is 3 or more. The etching method according to claim 1 or 2.

4. Ions in the plasma are attracted to the bottom portion, and the condensed or solidified layer formed on the bottom portion reacts with the bottom portion to advance etching. The etching method according to any one of claims 1 to 3.

5. After the step (a), the temperature of the substrate support is adjusted to −30° C. or lower. The etching method according to any one of claims 1 to 4.

6. (d) applying a bias voltage to the substrate support and etching the bottom portion with the generated plasma; In the steps (b) to (d), the temperature of the substrate support is adjusted to 0° C. or lower. The etching method according to any one of claims 1 to 5.

7. The bias voltage is pulsed. The etching method according to claim 6.

8. The bias voltage is a negative DC bias. The etching method according to claim 6 or 7.

9. 1. A plasma etching apparatus comprising: A chamber; a substrate support disposed within the chamber and supporting a substrate; a plasma generating unit for generating plasma in the chamber; A control unit, The control unit is (a) providing a substrate having a carbon-containing film on a substrate support; (b) etching the substrate with plasma generated from a gas containing H and O to form an etched shape having a bottom in the carbon-containing film; (c) selectively forming a condensed or solidified layer of H 2 O at the bottom of the etched shape by plasma generated from a gas containing H and O; A plasma etching apparatus, wherein the temperature of the substrate support part is adjusted to 0° C. or lower in the step (b).

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