Etching method and etching apparatus

Abstract

The present invention provides an etching method and an etching apparatus. The etching method includes a step of providing, a step of setting, and a step of etching. The step of providing supplies a substrate to a stage, the substrate having an etched film including a silicon oxide film and a mask formed on the etched film. The step of setting is a step of setting the temperature of the stage to a temperature below 0°C. The step of etching generates plasma from a gas and etches the silicon oxide film through the mask, the gas containing fluorine, nitrogen, and carbon, and the ratio F / N of the amount of fluorine to the amount of nitrogen being in the range of 0.5 to 10. According to the present invention, it is possible to suppress the expansion of CD (Critical Dimension) and improve the etching rate.

Description

Technical Field

[0001] The invention relates to an etching method and an etching device. Background Art

[0002] There is a technology for forming deep holes in a silicon oxide film or a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked and formed on a target object.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent document 1: Japanese Patent Application Publication No. 2016-39310. Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present invention provides an etching method and an etching device capable of suppressing the expansion of CD (Critical Dimension) and improving the etching rate.

[0008] Technical solutions to the problem

[0009] An etching method according to one embodiment of the present invention includes a providing step, a setting step, and an etching step. In the providing step, a substrate is provided on a stage, the substrate having an etched film including a silicon oxide film and a mask formed on the etched film. In the setting step, the temperature of the stage is set to a temperature below 0°C. In the etching step, plasma is generated from a gas to etch the silicon oxide film through the mask, the gas including fluorine, nitrogen, and carbon, and the ratio F / N of the amount of fluorine to the amount of nitrogen is in the range of 0.5 to 10.

[0010] Effects of the Invention

[0011] According to the present invention, it is possible to suppress the expansion of CD and improve the etching rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 FIG. 1 is a diagram showing an example of a plasma processing system according to an embodiment of the present invention.

[0013] Figure 2 FIG. 1 is a diagram showing an example of the structure of a substrate etched by the etching apparatus according to the present embodiment.

[0014] Figure 3 This is a flowchart showing an example of etching processing in this embodiment.

[0015] Figure 4 This is a diagram schematically illustrating an example of the principle of etching in this embodiment.

[0016] Figure 5 It is a graph showing the change in the etching rate in the experimental results.

[0017] Figure 6 It is a graph showing the change in CD in the experimental results.

[0018] Figure 7 It is a diagram showing an example of the experimental results when the flow rate ratio of HF / N2 gas is changed.

[0019] Figure 8 It is showing Figure 7 the change in the etching rate in the experimental results of

[0020] Figure 9 It is showing Figure 7 the change in CD in the experimental results of

[0021] Figure 10 It is a graph showing the temperature dependence in the experimental results.

[0022] Explanation of reference numerals

[0023] 1 Plasma processing system

[0024] 1a Plasma processing apparatus

[0025] 1b Control unit

[0026] 10 Reaction chamber

[0027] 11 Support part

[0028] 20 Gas supply part

[0029] 30 RF electric power supply part

[0030] 40 Exhaust system

[0031] 102 Silicon oxide film

[0032] 103 Mask

[0033] W Substrate Detailed implementation mode

[0034] Hereinafter, with reference to the drawings, the embodiments of the disclosed etching method and etching apparatus will be described in detail. In addition, the disclosed technology is not limited by the following embodiments.

[0035] There is a technology called HARC (High Aspect Ratio Contact) processing, which forms high aspect ratio holes in a silicon oxide film formed on a substrate, or a multilayer film formed by alternately laminating a silicon oxide film and a silicon nitride film. In HARC processing, nitrogen trifluoride (NF3) is used. However, NF3 has a high reactivity with mask materials such as SOC (Spin On Carbon) or amorphous carbon film (ACL: Amorphous Carbon Layer), etc., which causes CD to expand. Therefore, a technology that can suppress the expansion of CD and increase the etching rate is desired.

[0036] [Structure of Plasma Processing System 1]

[0037] Figure 1 It is a diagram showing an example of a plasma processing system in an embodiment of the present invention. As Figure 1 shown, in one embodiment, the plasma processing system 1 includes a plasma processing device 1a and a control unit 1b. The plasma processing device 1a is an example of an etching device for etching a silicon oxide film. The plasma processing device 1a includes a reaction chamber 10, a gas supply unit 20, a Radio Frequency (RF) electric power supply unit 30, and an exhaust system 40. In addition, the plasma processing device 1a includes a support portion 11 and an upper electrode shower head 12. The support portion 11 is disposed in the lower region of the plasma processing space 10s in the reaction chamber 10. The upper electrode shower head 12 is disposed above the support portion 11 and can function as a part of the ceiling of the reaction chamber 10.

[0038] The support portion 11 is configured to be able to support the substrate W in the plasma processing space 10s. In addition, the support portion 11 is also referred to as a stage. In one embodiment, the support portion 11 includes a lower electrode 111, an electrostatic chuck 112, and an edge ring 113. The electrostatic chuck 112 is disposed on the lower electrode 111 and can support the substrate W on the upper surface of the electrostatic chuck 112. The edge ring 113 is disposed so as to surround the substrate W on the upper surface of the peripheral portion of the lower electrode 111. In addition, although not shown in the figure, in one embodiment, the support portion 11 may include a temperature adjustment module configured to be able to adjust at least one of the electrostatic chuck 112 and the substrate W to a target temperature. The temperature adjustment module may include a heater, a flow path, or a combination thereof. A temperature adjustment fluid such as a refrigerant or a heat transfer gas flows in the flow path. The temperature adjustment module can be set as a target temperature, for example, so that the substrate W becomes any temperature within the range of 50°C to -100°C.

[0039] The upper electrode showerhead 12 is configured to supply one or more than one processing gas from the gas supply unit 20 to the plasma processing space 10s. In one embodiment, the upper electrode showerhead 12 has a gas inlet 12a, a gas diffusion chamber 12b, and a plurality of gas outlets 12c. The gas inlet 12a is in fluid communication with the gas supply unit 20 and the gas diffusion chamber 12b. The plurality of gas outlets 12c are in fluid communication with the gas diffusion chamber 12b and the plasma processing space 10s. In one embodiment, the upper electrode showerhead 12 is configured to supply one or more than one processing gas from the gas inlet 12a to the plasma processing space 10s via the gas diffusion chamber 12b and the plurality of gas outlets 12c.

[0040] The gas supply unit 20 may include one or more than one gas source 21 and one or more than one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply one or more than one processing gas from the corresponding gas source 21 to the gas inlet 12a via the corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Moreover, the gas supply unit 20 may include one or more than one flow modulator for modulating or pulsing the flow rate of one or more than one processing gas.

[0041] The RF electric power supply unit 30 is configured to supply RF electric power, for example, one or more than one RF signal, to one or more than one of the lower electrode 111, the upper electrode showerhead 12, or both the lower electrode 111 and the upper electrode showerhead 12. Thereby, plasma can be generated from one or more than one processing gas supplied to the plasma processing space 10s. Thus, the RF electric power supply unit 30 can function as at least a part of a plasma generation unit that generates plasma from one or more than one processing gas in the reaction chamber. In one embodiment, the RF electric power supply unit 30 includes two RF generation units 31a, 31b and two matching circuits 32a, 32b. In one embodiment, the RF electric power supply unit 30 is configured to supply a first RF signal from the first RF generation unit 31a to the lower electrode 111 via the first matching circuit 32a. For example, the first RF signal may have a frequency in the range of 27 MHz to 100 MHz.

[0042] In addition, in one embodiment, the RF electric power supply unit 30 is configured to be able to supply a second RF signal from the second RF generation unit 31b to the lower electrode 111 via the second matching circuit 32b. For example, the second RF signal may have a frequency in the range of 400 kHz to 13.56 MHz. Instead of this method, a DC (Direct Current) pulse generation unit may be used in place of the second RF generation unit 31b.

[0043] In addition, although not shown in the drawings, other embodiments are also considered in the present invention. For example, in an alternative embodiment, the RF electric power supply unit 30 may be configured to be able to supply a first RF signal from an RF generation unit to the lower electrode 111, supply a second RF signal from another RF generation unit to the lower electrode 111, and supply a third RF signal from yet another RF generation unit to the lower electrode 111. In addition, in other alternative embodiments, a DC voltage may be applied to the upper electrode showerhead 12.

[0044] In addition, in various embodiments, the amplitude of one or more RF signals (i.e., the first RF signal, the second RF signal, etc.) may be pulsed or modulated. Amplitude modulation may include processing the amplitude of the RF signal between an on state and an off state or between two or more different on states.

[0045] The exhaust system 40 may be connected, for example, to an exhaust port 10e provided at the bottom of the reaction chamber 10. The exhaust system 40 may include a pressure valve and a vacuum pump. The vacuum pump may include a turbo molecular pump, a roughing pump, or a combination thereof.

[0046] In one embodiment, the control unit 1b processes computer-executable commands that cause the plasma processing apparatus 1a to perform various steps described in the present invention. The control unit 1b may be configured to be able to control each element of the plasma processing apparatus 1a to perform the various steps described herein. In one embodiment, part or all of the control unit 1b is included in the plasma processing apparatus 1a. The control unit 1b may include, for example, a computer 51. The computer 51 may include, for example, a processing unit (CPU: Central Processing Unit) 511, a storage unit 512, and a communication interface 513. The processing unit 511 may be configured to be able to perform various control actions based on programs stored in the storage unit 512. The storage unit 512 may include a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 513 may communicate with the plasma processing apparatus 1a via a communication line such as a LAN (Local Area Network).

[0047] [Structure of Substrate W]

[0048] Figure 2 It is a diagram showing an example of the structure of a substrate etched by the etching apparatus of the present embodiment.

[0049] The substrate W is, for example, as Figure 2 shown, has a silicon oxide film 102 as an etched film on a silicon substrate 101. Further, on the silicon oxide film 102, a mask 103 having an opening with a predetermined pattern is formed. Further, the etched film may also be a multilayer film formed by alternately laminating a silicon oxide film and a silicon nitride film. Further, the etched film may contain a silicon (Si) film in addition to the silicon oxide film. Further, the etched film may contain a Low-k film in addition to the silicon oxide film. The Low-k film may be of the SiOCN type.

[0050] The mask 103 may be an organic mask or a metal-containing mask. Examples of the organic mask are a photoresist, a spin-on carbon (SOC) film, and an amorphous carbon (ACL) film. The metal-containing masks are tungsten, tungsten carbide, titanium nitride, titanium oxide, etc. The mask 103 uses a carbon-containing mask made of a carbon-containing material when a carbon-free gas is used as the processing gas.

[0051] [Etching Method]

[0052] Next, the etching method of the present embodiment will be described. Figure 3This is a flowchart showing an example of etching processing in this embodiment.

[0053] In the etching method of this embodiment, the control unit 1b opens the opening portion not shown in the figure, and sends the substrate W formed with the silicon oxide film 102 and the mask 103 thereon into the reaction chamber 10, and places it on the electrostatic chuck 112 of the support portion 11. A DC voltage is applied to the electrostatic chuck 112 to hold the substrate W on the electrostatic chuck 112. Thereafter, the control unit 1b closes the opening portion and controls the exhaust system 40 to exhaust the gas from the plasma processing space 10s so that the atmosphere of the plasma processing space 10s becomes a specified vacuum degree. In addition, the control unit 1b adjusts the temperature of the substrate W to a specified temperature, for example, below 0°C, by controlling the temperature adjustment module not shown in the figure (step S1). In addition, the temperature of the substrate W is more preferably adjusted to below -30°C.

[0054] Next, the control unit 1b supplies a mixed gas of HF and N2 (hereinafter referred to as HF / N2 gas) to the gas inlet 12a. After the processing gas is supplied to the gas inlet 12a, it is supplied to the gas diffusion chamber 12b and diffused. After the processing gas diffuses in the gas diffusion chamber 12b, it is supplied to the plasma processing space 10s of the reaction chamber 10 in a shower shape through the plurality of gas outlets 12c and introduced into the plasma processing space 10s.

[0055] The control unit 1b supplies RF signals for plasma excitation and bias to the support unit 11 by controlling the RF power supply unit 30. In the plasma processing space 10s, plasma is generated by supplying the RF signal for plasma excitation to the support unit 11. The plasma is accelerated toward the substrate W by supplying the RF signal for bias to the support unit 11. The silicon oxide film 102 as the etched film is etched by the plasma generated in the plasma processing space 10s (step S2).

[0056] Specifically, the control unit 1b etches the silicon oxide film 102 by plasma generated from the HF / N2 gas through the mask 103 in the plasma processing space 10s into which the HF / N2 gas as the processing gas is introduced. In the etching step, the silicon oxide film 102 is etched so that the aspect ratio of the hole formed in the silicon oxide film 102 becomes a predetermined value (for example, 5 or more).

[0057] Here, the plasma generated in the plasma processing space for 10 s is a plasma using hydrogen, fluorine, and nitrogen from HF / N2 gas and carbon from the mask 103 as reactive species. The ratio F / N of the amount of fluorine contained in the plasma to the amount of nitrogen can be set according to the flow rate ratio of HF gas to N2 gas. For example, in the case of HF / N2 gas, the N2 gas is set in the range of 5% to 50% with respect to the total flow rate, that is, the ratio F / N is in the range of 0.5 to 10. In addition, it is preferable to set the ratio F / N in the range of 1.5 to 10. More preferably, the ratio F / N is set to approximately 4.5. This corresponds to the case of HF / N2 gas, where the flow rate ratio of N2 gas is in the range of 5% to 25%, and more preferably approximately 10%. When using other gases as the processing gas, the flow rate ratio of the processing gas is adjusted based on the ratio F / N. In addition, as other processing gases, for example, a mixed gas of H2, CF4, and N2 (hereinafter referred to as H2 / CF4 / N2 gas) can be used.

[0058] Here, use Figure 4 , to illustrate the principle of etching with N-type gas. Figure 4 is a diagram schematically showing an example of the principle of etching in the present embodiment. In Figure 4 state 201, plasma of HF / N2 gas or H2 / CF4 / N2 gas is irradiated onto the holes of the silicon oxide film 102. That is, in the plasma, a cyanide-containing gas (CN-type gas) can be included as a reactive species. In this way, as shown in state 202, CN-type radicals are adsorbed to the region 104 inside the holes (the etched portion). In addition, although the vapor pressure of the CN-type gas is high, by lowering the temperature of the substrate W, the CN-type radicals can be adsorbed to the region 104. In addition, examples of cyanide (CN group) include HCN, CNF, C2N2, etc.

[0059] When CN-type radicals are adsorbed to the region 104, as shown in state 203, the region 104 where N2+ ions collide and the region 105 of the silicon oxide film 102 below it can be removed. That is, the Si unsaturated bond generated by ion bombardment is terminated with CN, and the bond of SiO2 is cut off, so the etching rate increases. In addition, the bond of N2 is very strong and difficult to dissociate, so isotropic etching caused by N radicals can be suppressed. That is, by repeating from state 201 to state 203, the expansion of CD can be suppressed and the etching rate can be increased. In this way, in the present embodiment, the CN compound generated by adding N2 also contributes to the increase in the etching rate.

[0060] Return to Figure 3Explanation. During the etching step, the control unit 1b determines whether a specified shape has been obtained (step S3). If the control unit 1b determines that the specified shape has not been obtained (step S3: No), the process returns to step S2. On the other hand, if the control unit 1b determines that the specified shape has been obtained (step S3: Yes), the process ends.

[0061] When the control unit 1b ends the process, it stops supplying the RF signal to the support unit 11 by controlling the RF power supply unit 30. The control unit 1b opens an opening (not shown). The substrate W is sent out from the plasma processing space 10s of the reaction chamber 10 through the opening.

[0062] [Experimental Results]

[0063] Next, Figures 5 to 9 will be used to explain the experimental results. In addition, in the following explanations, the temperature represents the temperature at the start of plasma processing (etching) of the substrate W. First, Figure 5 and Figure 6 will be used to explain the comparison of etching rates in cases where various gases are added. In each experimental result of cases where various gases are added, the total flow rate is set to 500 sccm, and 50 sccm of various gas X is added to 450 sccm of HF gas, and the silicon oxide film and the silicon nitride film are etched under the following processing conditions. In addition, in Figure 5 and Figure 6 , the silicon oxide film is denoted as Ox, and the silicon nitride film is denoted as Nit. In addition, the various gas X is any one of N2 gas, NF3 gas, SF6 gas, and CF4 gas. In addition, when no various gas X is added, the flow rate of HF gas is 500 sccm. In addition, in the processing conditions, "CW" for the electric power of the RF signal represents continuous wave.

[0064] <Processing Conditions>

[0065] (Etching)

[0066] Pressure inside the reaction chamber 10: 25 mTorr (3.333 Pa)

[0067] Electric power of the first RF signal (40 MHz): 4.4 kW (CW)

[0068] Electric power of the second RF signal (400 kHz): 7.0 kW (CW)

[0069] Processing time: 30 seconds

[0070] Temperature: -70 °C

[0071] Processing gas: HF / various gases X = 450 / 50 sccm

[0072] Figure 5 is a graph showing the change in etching rate in the experimental results. Figure 6 is a graph showing the change in CD in the experimental results. In Figure 5 and Figure 6 the increase and decrease are shown based on the case of HF gas. In addition, Figure 5 the unit of the difference in etching rate (ΔE / R) of Figure 6 is [nm / min], and the unit of ΔCD of Figure 5 and Figure 6 is [nm]. As shown in Figure 6 and

[0073] it can be seen that in the case of N-type gases (N2 gas, NF3 gas), when N2 gas is "508" and NF3 gas is "530", the difference (increase amount) in the etching rate of the silicon oxide film increases significantly. On the other hand, it can be seen that in the case of SF6 gas and CF4 gas, when SF6 gas is "214" and CF4 gas is "86", the difference (increase amount) in the etching rate of the silicon oxide film is small. In addition, for the silicon nitride film, the etching rate increases in the case of all gases of N2 gas, NF3 gas, SF6 gas, and CF4 gas. In addition, regarding CD, as shown in Figures 7 to 9 it can be seen that compared with other gases, NF3 deteriorates significantly. As described above, in HF / N2 gas, the expansion of CD can be suppressed and the etching rate of the silicon oxide film can be increased. Figure 7 is a graph showing an example of the experimental results when the flow ratio of HF / N2 gas is changed. In Figure 7 in each experimental result, the total flow rate is set to 200 sccm, the flow ratio of N2 gas is set to 0%, 5%, 10%, 25%, 50%, and the silicon oxide film and the silicon nitride film are etched under the following processing conditions. In addition, in the processing conditions, "CW" of the electric power of the RF signal indicates continuous wave. In addition, in Figures 7 to 9 the silicon oxide film is denoted as Ox and the silicon nitride film is denoted as Nit. In addition, in Figure 7 the mask etching rate (mask ER), the silicon oxide film etching rate (OxER), the silicon nitride film etching rate (NitER), and the selectivity are shown for each flow ratio. In addition, the unit of the etching rate is [nm / min].

[0074] <Processing conditions>

[0075] (Etching)

[0076] Pressure inside reaction chamber 10: 25 mTorr (3.333 Pa)

[0077] Electric power of the first RF signal (40 MHz): 4.4 kW (CW)

[0078] Electric power of the second RF signal (400 kHz): 7.0 kW (CW)

[0079] Processing time: 30 seconds

[0080] Temperature: -70 °C

[0081] Flow rate of processing gas (HF / N2): 200 / 0 sccm (0%)

[0082] : 190 / 10 sccm (5%)

[0083] : 180 / 20 sccm (10%)

[0084] : 150 / 50 sccm (25%)

[0085] : 100 / 100 sccm (50%)

[0086] Figure 8 represents Figure 7 a graph showing the change in etching rate in the experimental results of Figure 9 represents Figure 7 a graph showing the change in CD in the experimental results of Figure 8 and Figure 9 the increase and decrease are shown with the case where the flow rate ratio of N2 gas is 0% as the reference. In addition, Figure 8 the unit of the difference in etching rate (ΔE / R) of Figure 9 is [nm / min], and Figures 7 to 9 the unit of the difference in CD (ΔCD) of Figure 9 is [nm / min]. As Figures 7 to 9 shown, it can be seen that for the silicon oxide film, the difference in etching rate becomes the maximum "460" when the flow rate ratio of N2 gas is 10%. On the other hand, it can be seen that for the silicon nitride film, although the difference in etching rate also becomes the maximum "330" when the flow rate ratio of N2 gas is 10% as in the case of the silicon oxide film, the difference in etching rate is "-226" when the flow rate ratio of N2 gas is 50%, which is lower than the case of 0%. In addition, as Figure 9 shown, it can be seen that for the silicon oxide film, CD does not expand when the flow rate ratio of N2 gas is 5% - 50%. In addition, for the silicon nitride film, CD does not expand when the flow rate ratio of N2 gas is 5% - 25%, and CD expands to some extent at 50%. That is, it can be seen that the change in the flow rate ratio of N2 gas only affects the etching rate.

[0087] Next, the dependence of the etching rate on the electric power (LF power) of the second RF signal will be described. When N2 gas is not added to the HF gas, the difference (ΔE / R) in the etching rate between when N2 gas is added and when it is not added depends on the electric power of the second RF signal. Plotting the difference in the etching rate against the electric power of the second RF signal as a graph, when extrapolating the two points of "0 kW" and "7 kW", the graph becomes a straight line connecting "-800" and "200" of the difference (ΔE / R) in the etching rate. In addition, the unit of the difference (ΔE / R) in the etching rate is [nm / min]. In this graph, the electric power of the second RF signal at which the difference in the etching rate exceeds "0" is about 6 kW, and after normalization it is about 8.49 W / cm 2 level. That is, when the electric power of the second RF signal is 6 kW or more, adding N2 gas has the effect of increasing the etching rate compared to the case where N2 gas is not added. In addition, when the power of the ions exceeds about 8.49 W / cm 2 level, the nitrided region is removed and the etching of the bottom progresses.

[0088] Next, the temperature dependence in the case where N2 gas is added to the H2 / CF4 gas will be described. Among the experimental results for the cases where the temperature was changed, the substrate W before etching was set to -70 °C, -40 °C, and 20 °C, the processing gases were H2 / CF4 gas and H2 / CF4 / N2 gas, and the silicon oxide film and the silicon nitride film were etched under the following processing conditions. In addition, in the processing conditions, "CW" for the electric power of the RF signal indicates continuous wave.

[0089] <Processing conditions>

[0090] (Etching)

[0091] Pressure inside reaction chamber 10: 25 mTorr (3.333 Pa)

[0092] Electric power of the first RF signal (40 MHz): 4.4 kW (CW)

[0093] Electric power of the second RF signal (400 kHz): 7.0 kW (CW)

[0094] Processing time: 30 seconds

[0095] Temperature: -70 °C, -40 °C, 20 °C

[0096] Processing gas: H2 / CF4 / N2 = 150 / 50 / 0 sccm

[0097] : H2 / CF4 / N2 = 150 / 50 / 20 sccm

[0098] Figure 10 It is a graph showing the temperature dependence in the experimental results. Figure 10 The shown graph 230 is a graph plotting the etching rate curve of the silicon oxide film in the experimental results. Graph 231 shows the temperature dependence of the etching rate in the case of H2 / CF4 gas. Graph 232 shows the temperature dependence of the etching rate in the case of H2 / CF4 / N2 gas. Compare the temperature dependence of the etching rate in the case of H2 / CF4 gas shown in graph 231 with that in the case of H2 / CF4 / N2 gas shown in graph 232. In addition, the unit of the etching rate is [nm / min]. In the case of H2 / CF4 gas, it is "460" at -70°C, "294" at -40°C, and "444" at 20°C. On the other hand, in the case of H2 / CF4 / N2 gas, it is "642" at -70°C, "488" at -40°C, and "222" at 20°C. That is, from -70°C via -40°C to around 0°C, the etching rate of H2 / CF4 / N2 gas is higher than that of H2 / CF4 gas. On the other hand, from around 0°C to 20°C, conversely, the etching rate of H2 / CF4 gas is higher than that of H2 / CF4 / N2 gas. That is, it can be seen that the effect of increasing the etching rate by adding N2 works in the low temperature region. On the other hand, it can be seen that the effect is opposite at room temperature.

[0099] Next, in the experimental results, the temperature dependence of the etching rate in the case of H2 / CF4 gas is compared with that in the case of H2 / CF4 / N2 gas for the silicon nitride film. In addition, the unit of the etching rate is [nm / min]. In the case of H2 / CF4 gas, it is "2104" at -70°C, "2350" at -40°C, and "1790" at 20°C. On the other hand, in the case of H2 / CF4 / N2 gas, it is "1920" at -70°C, "96" at -40°C, and "714" at 20°C. That is, at -40°C under the condition of H2 / CF4 / N2 gas, the etching rate of the silicon nitride film is "96", which is lower than "488" of the etching rate of the silicon oxide film. From this, it can be known that the condition of -40°C and H2 / CF4 / N2 gas can be applied to SAC (Self-Aligned Contact) processing. That is, under this condition, in the SAC processing of a multilayer film stacked with a silicon nitride film (SiN) and a silicon oxide film (SiO2), the silicon oxide film (SiO2) can be selectively etched. In addition, when applied to SAC processing, as the temperature condition, a range of -50°C to -30°C is preferred, and -40°C is more preferred.

[0100] In addition, in the above-mentioned embodiment, the plasma processing system 1 is an example of an etching device for etching silicon oxide films, namely, a plasma processing device 1a and a control unit 1b, but it can also be an etching device for etching silicon oxide films in a form including the plasma processing device 1a and the control unit 1b.

[0101] As described above, according to the present embodiment, an etching device (plasma processing system 1) for etching a silicon oxide film includes a reaction chamber, a stage (support portion 11), a plasma generating portion, and a control portion 1b. The control portion 1b is configured to be able to control the device so as to provide a substrate W having an etched film including a silicon oxide film 102 and a mask 103 formed on the etched film onto the stage. The control portion is configured to be able to control the device so that the temperature of the stage becomes a temperature below 0°C. The control portion 1b is configured to be able to control the device so that plasma is generated from a gas to etch the silicon oxide film 102 through the mask 103, wherein the gas contains fluorine, nitrogen, and carbon, and the ratio F / N of the amount of fluorine to the amount of nitrogen is in the range of 0.5 to 10. As a result, the expansion of CD can be suppressed and the etching rate can be improved.

[0102] According to the present embodiment, the mask 103 is a mask containing carbon. As a result, carbon can be supplied to the plasma during etching using HF / N2 gas.

[0103] In addition, according to this embodiment, the gas further includes a hydrogen-containing gas. As a result, the etching rate can be increased in a low-temperature environment.

[0104] In addition, according to the present embodiment, the gas includes a carbon-containing gas. As a result, the mask 103 that does not contain carbon can be used.

[0105] In addition, according to the present embodiment, the gas includes a gas containing HF and N 2. As a result, the increase in CD can be suppressed and the etching rate can be increased.

[0106] Furthermore, according to the present embodiment, the temperature of the substrate W (temperature of the mounting table) before etching is set to be -30°C or lower. As a result, the etching rate can be further increased.

[0107] In addition, according to the present embodiment, the film to be etched is a stacked film further including a silicon nitride film. As a result, the etching rate can be increased also in the stacked film.

[0108] In addition, according to this embodiment, the gas includes a cyanide-containing gas. As a result, the etching rate can be further increased.

[0109] In addition, according to the present embodiment, etching is performed such that the final aspect ratio of the silicon oxide film 102 is 5 or more. As a result, in deep hole processing, an increase in CD can be suppressed and the etching rate can be increased.

[0110] As described above, various exemplary embodiments have been described, but the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and changes can be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0111] In addition, in the above embodiment, as the processing gas, a gas containing fluorine and nitrogen, that is, HF / N2 gas, is used, but the present invention is not limited thereto. For example, in addition to NF3 gas, various gases such as H2 / CF4 / N2 gas and a gas containing a cyanide (CN group) such as HCN, CNF, and C2N2 can be used in a part of the experimental results. In addition, for example, depending on the material of the film to be etched and the mask, a gas containing silicon and fluorine or a gas containing a metal element (Ti, W) and chlorine can be used.

[0112] In addition, in the above embodiment, as the plasma source, the plasma processing apparatus 1a that uses capacitively coupled plasma to etch the substrate W and the like is described as an example, but the disclosed technology is not limited thereto. The plasma source only needs to be a device that uses plasma to process the substrate W, and is not limited to capacitively coupled plasma. For example, inductively coupled plasma, microwave plasma, or any other plasma source can be used.

Claims

1. An etching method, characterized in that, Comprising: The step of providing a substrate onto a mounting table, wherein the substrate has an etched film including a silicon oxide film and a carbon-containing mask formed on the etched film; The step of setting the temperature of the mounting table to a temperature below 0°C; and The step of generating plasma from a process gas including HF gas and N2 gas, wherein the flow rate of the N2 gas is 5% to 50% of the total flow rate of the HF gas and the N2 gas; and The step of etching the silicon oxide film through the carbon-containing mask using the generated plasma.

2. The etching method according to claim 1, characterized in that: The process gas includes a carbon-containing gas.

3. The etching method according to claim 1 or 2, characterized in that: The setting step is set so that the substrate becomes a temperature below -30°C.

4. The etching method according to claim 1 or 2, characterized in that: The etched film is a stacked film further including a silicon nitride film.

5. The etching method according to claim 1 or 2, characterized in that: The process gas includes a cyanide-containing gas.

6. The etching method according to claim 1 or 2, characterized in that: The etching step is performed to etch so that the final aspect ratio of the silicon oxide film is 5 or more.

7. An etching apparatus for a silicon oxide film, characterized in that, Comprising: A reaction chamber; A mounting table provided in the reaction chamber; A plasma generation unit that generates plasma in the reaction chamber; And A control unit, The control unit is configured to be able to control the etching apparatus to provide a substrate onto the mounting table, wherein the substrate has an etched film including a silicon oxide film and a carbon-containing mask formed on the etched film, The control unit is configured to be able to control the etching apparatus to set the temperature of the mounting table to a temperature below 0°C, The control unit is configured to be able to control the etching apparatus to generate plasma from a process gas including HF gas and N2 gas, and use the generated plasma to etch the silicon oxide film through the carbon-containing mask, wherein the flow rate of the N2 gas is 5% to 50% of the total flow rate of the HF gas and the N2 gas.

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