Method for manufacturing semiconductor device, substrate processing method, recording medium, and substrate processing apparatus

Abstract

The present application includes (a) a step of carrying a substrate having a film formed on a surface into a processing vessel; (b) a step of generating reaction species containing oxygen and reaction species of a rare gas by plasma-izing a mixed gas containing a rare gas and an oxygen-containing gas; and (c) a step of supplying the reaction species containing oxygen to the substrate together with the reaction species of the rare gas to oxidize the film, wherein in (b), the partial pressure P N of the rare gas in the processing vessel is set to 0.4 or less with respect to the total pressure P T of the mixed gas. The ratio P N of the rare gas is set to 0.4 or less with respect to the total pressure P T of the mixed gas.

Description

Technical Field

[0001] This disclosure relates to methods for manufacturing semiconductor devices, methods for processing substrates, recording media, and apparatus for processing substrates. Background Technology

[0002] As part of the manufacturing process of semiconductor devices, sometimes a process is performed to modify the film formed on the surface of a substrate using plasma (see, for example, Patent Documents 1 and 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-75579

[0006] Patent Document 2: International Publication 2018 / 179038 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this disclosure is to provide techniques that can improve the properties of films formed on the surface of a substrate.

[0009] Methods for solving problems

[0010] According to one aspect of this disclosure, the following technology is provided, which has the following steps:

[0011] (a) The process of transferring a substrate with a film formed on its surface into a processing container;

[0012] (b) A step of plasma-generating a mixture of a rare gas and an oxygen-containing gas to produce an oxygen-containing reaction species and the aforementioned rare gas reaction species; and,

[0013] (c) The process of supplying the above-mentioned oxygen-containing reactants together with the above-mentioned rare gas reactants to the above-mentioned substrate to oxidize the above-mentioned film.

[0014] In (b) above, the partial pressure P of the rare gas in the processing container is... N Relative to the total pressure P of the above mixed gas T The ratio, i.e., P N / P T Set it to a size of 0.4 or less.

[0015] The effects of the invention

[0016] According to this disclosure, it is possible to improve the properties of a film formed on the surface of a substrate. Attached Figure Description

[0017] [ Figure 1 [A schematic diagram of a substrate processing apparatus 100 preferred in one embodiment of this disclosure, and a diagram showing a portion of the processing furnace 202 in longitudinal cross-section.]

[0018] [ Figure 2 The diagram illustrates the principle of plasma generation in one embodiment of this disclosure.

[0019] [ Figure 3 [This is a schematic configuration diagram of the controller 221 of the substrate processing apparatus 100, which is preferably used in one embodiment of this disclosure, and a block diagram showing the control system of the controller 221.]

[0020] [ Figure 4 [Example: The wet etching resistance of the modified film is compared with the partial pressure ratio P of the rare gas in the oxidation treatment.] N / P T A diagram illustrating the relationship.

[0021] [ Figure 5 [Graph showing the results of wet etching resistance test of the modified film.] Detailed Implementation

[0022] <One way this public text is published>

[0023] See below. Figures 1-3 One way to describe this public text.

[0024] (1) Substrate processing device

[0025] like Figure 1 As shown, the substrate processing apparatus 100 includes a processing furnace 202 that houses a wafer 200 as a substrate and performs plasma processing. The processing furnace 202 includes a processing container 203 that constitutes a processing chamber 201. The processing container 203 has a dome-shaped upper container 210 and a bowl-shaped lower container 211. The processing chamber 201 is formed by covering the lower container 211 with the upper container 210.

[0026] A gate valve 244, serving as an inlet / outlet (separation valve), is provided on the lower side wall of the lower container 211. By opening the gate valve 244, the wafer 200 can be moved into and out of the processing chamber 201 via the inlet / outlet 245. By closing the gate valve 244, the airtightness of the processing chamber 201 can be maintained.

[0027] like Figure 2As shown, the processing chamber 201 includes a plasma generation space 201a and a substrate processing space 201b communicating with the plasma generation space 201a and processing the wafer 200. A resonant coil 212, described later, is disposed around the plasma generation space 201a and on the outer periphery of the processing container 203. The plasma generation space 201a refers to the space where plasma is generated and is located within the processing chamber 201, for example, at the lower end of the resonant coil 212. Figure 1 The space is located further up than the single-dotted line in the image. On the other hand, the substrate processing space 201b refers to the space where the wafer 200 is processed by plasma and is located further down than the lower end of the resonant coil 212.

[0028] A susceptor 217 serving as a substrate mount is disposed at the center of the bottom side within the processing chamber 201. A substrate mounting surface 217d for mounting the wafer 200 is provided on the upper surface of the susceptor 217. A heater 217b serving as a heating mechanism is embedded inside the susceptor 217. By supplying power to the heater 217b via the heater power regulating mechanism 276, the wafer 200 mounted on the substrate mounting surface 217d can be heated to a predetermined temperature, for example, within the range of 25 to 1000°C.

[0029] The support 217 is electrically insulated from the lower container 211. An impedance adjustment electrode 217c is installed inside the support 217. The impedance adjustment electrode 217c is grounded via an impedance variable mechanism 275, which serves as an impedance adjustment unit. The impedance variable mechanism 275 is configured to include a coil, a variable capacitor, etc., and by controlling the inductance and resistance of the coil, the capacitance of the variable capacitor, etc., the impedance of the impedance adjustment electrode 217c can be varied within a predetermined range from approximately 0 Ω to the parasitic impedance value of the processing chamber 201. Therefore, the potential (bias voltage) of the wafer 200 in plasma processing can be controlled via the impedance adjustment electrode 217c and the support 217.

[0030] A support lifting mechanism 268 is provided below the support 217 to raise and lower the support 217. Three through holes 217a are provided in the support 217. On the bottom surface of the lower container 211, three support pins 266, serving as supports for the wafer 200, are provided corresponding to each of the three through holes 217a. When the support 217 is lowered, the front ends of each of the three support pins 266 pass through their respective through holes 217a and protrude towards the upper surface of the support 217 compared to the substrate mounting surface 217d of the support 217. This allows the wafer 200 to be held from below.

[0031] A gas supply head 236 is provided above the processing chamber 201, that is, above the upper container 210. The gas supply head 236 is configured to have a cap-shaped cover 233, a gas inlet 234, a buffer chamber 237, an opening 238, a shielding plate 240, and a gas outlet 239, and supplies gas into the processing chamber 201. The buffer chamber 237 functions as a dispersion space to disperse the gas introduced through the gas inlet 234.

[0032] The downstream ends of gas supply pipe 232a (supplying rare gases such as helium (He), oxygen supply pipe 232b (supplying oxygen-containing gases such as oxygen (O2), and hydrogen-containing gases such as hydrogen (H2)) and gas supply pipe 232c (supplying hydrogen-containing gases such as hydrogen (H2)) are connected to gas inlet 234 in a confluence manner. On gas supply pipe 232a, starting from the upstream side of the gas flow, a rare gas supply source 250a, a mass flow controller (MFC) 252a (serving as a flow control device), and a valve 253a (serving as an on / off valve) are sequentially arranged. On gas supply pipe 232b, starting from the upstream side of the gas flow, an oxygen-containing gas supply source 250b, an MFC 252b, and a valve 253b are sequentially arranged. On gas supply pipe 232c, starting from the upstream side of the gas flow, a hydrogen-containing gas supply source 250c, an MFC 252c, and a valve 253c are sequentially arranged. A valve 243a is installed downstream of the confluence of gas supply pipes 232a to 232c. By opening and closing valves 253a to 253c and 243a, the flow rate can be regulated using MFCs 252a to 252c, and rare gases, O-containing gases, and H-containing gases can be supplied to the processing container 203 respectively. It should be noted that it can also be configured to supply N2 gas, which is an inactive gas, in addition to the various gases mentioned above, from gas supply pipes 232a to 232c.

[0033] The mixed gas containing rare gases, O-containing gases, and H-containing gases functions by being plasma-treated and supplied to the wafer 200 in the substrate processing step described later, thereby modifying (oxidizing) the film formed on the surface of the wafer 200. The O-containing gas functions as an oxidant in the substrate processing step. While the H-containing gas alone cannot achieve oxidation, it functions by reacting with the O-containing gas under specific conditions in the substrate processing step, thereby generating reactants (oxidizing agents, reactive agents) such as hydroxyl radicals (OH radicals), thus improving the efficiency of the oxidation process. The rare gases function by suppressing the deactivation of the generated oxygen-containing reactants or increasing their activity in the substrate processing step, promoting and maintaining the oxidation effect brought about by the oxygen-containing reactants. Regarding N2 gas, it is used in the substrate processing step without being plasma-treated, serving as a purge gas, etc.

[0034] The first supply system (rare gas supply system) mainly consists of gas supply head 236 (cover 233, gas inlet 234, buffer chamber 237, opening 238, shielding plate 240, gas outlet 239), gas supply pipe 232a, MFC 252a, valves 253a and 243a). The second supply system (including O gas supply system and oxidant supply system) mainly consists of gas supply head 236, gas supply pipe 232b, MFC 252b, valves 253b and 243a. The third supply system (including H gas supply system) mainly consists of gas supply head 236, gas supply pipe 232c, MFC 252c, valves 253c and 243a. It is worth considering including the third gas supply system within the second gas supply system.

[0035] An exhaust port 235 for venting exhaust from the processing chamber 201 is provided on the side wall of the lower container 211. The exhaust port 235 is connected to the upstream end of the exhaust pipe 231. On the exhaust pipe 231, starting from the upstream side, an APC (Auto Pressure Controller) valve 242, a valve 243b serving as a pressure regulator (pressure regulating unit), and a vacuum pump 246 serving as a vacuum exhaust device are sequentially arranged. The exhaust unit is mainly composed of the exhaust port 235, the exhaust pipe 231, the APC valve 242, and the valve 243b. The vacuum pump 246 can be included within the exhaust unit.

[0036] A spiral resonant coil 212 is provided on the outer periphery of the processing chamber 201, that is, on the outer side of the side wall of the upper container 210, in a manner that surrounds the processing container 203. An RF (Radio Frequency) sensor 272, a high-frequency power supply 273, and a frequency matching unit (frequency control unit) 274 are connected to the resonant coil 212. A shielding plate 223 is provided on the outer periphery of the resonant coil 212.

[0037] The high-frequency power supply 273 is configured to supply high-frequency power to the resonant coil 212. An RF sensor 272 is disposed on the output side of the high-frequency power supply 273. The RF sensor 272 is configured to monitor information about the traveling wave and reflected wave of the high-frequency power supplied from the high-frequency power supply 273. The frequency matcher 274 is configured to match the frequency of the high-frequency power output from the high-frequency power supply 273 in a manner that minimizes the reflected wave, based on information about the reflected wave monitored by the RF sensor 272.

[0038] Both ends of the resonant coil 212 are electrically grounded. One end of the resonant coil 212 is grounded via a movable tap 213. The other end of the resonant coil 212 is grounded via a fixed grounding terminal 214. A movable tap 215 is provided between these two ends of the resonant coil 212, allowing the position for receiving power from the high-frequency power supply 273 to be arbitrarily set. With the above configuration, when initially setting up the substrate processing apparatus 100 or changing the processing conditions, the electrical length and impedance of the resonant coil 212 can be finely adjusted, and the resonant characteristics can be easily made approximately equal to those of the high-frequency power supply 273, etc.

[0039] The shielding plate 223 is configured to shield the electromagnetic wave leakage from the resonant coil 212 to the outside, and forms a capacitance component between it and the resonant coil 212 required for constituting the resonant circuit.

[0040] The plasma generation unit (plasma generation section) mainly consists of a resonant coil 212, an RF sensor 272, and a frequency matching unit 274. A high-frequency power supply 273 and a shielding plate 223 can be included within the plasma generation unit.

[0041] The following uses Figure 2 The operation of the plasma generation unit and the properties of the generated plasma are further explained.

[0042] The resonant coil 212 is configured to function as a high-frequency inductively coupled plasma (ICP) electrode. The winding diameter, winding pitch, and number of turns of the resonant coil 212 are set to generate a standing wave of a specified wavelength and to resonate in a full-wavelength mode. The electrical length of the resonant coil 212, i.e., the electrode length between ground and resonant coil, is adjusted to be an integer multiple of the wavelength of the high-frequency power supplied from the high-frequency power source 273. These configurations, the power supplied to the resonant coil 212, and the magnetic field strength generated in the resonant coil 212 are appropriately determined by examining the shape of the substrate processing apparatus 100 and the processing requirements. As an example, the effective cross-sectional area of ​​the resonant coil 212 is set to 50–300 mm². 2 The coil diameter is set to 200–500 mm, and the number of turns is set to 2–60. The high-frequency power supplied to the resonant coil 212 is set to 0.5–5 kW, preferably 1.0–4.0 kW, and the frequency is set to 800 kHz–50 MHz. The magnetic field generated in the resonant coil 212 is set to 0.01–10 Gauss. In this embodiment, as a preferred example, the frequency of the high-frequency power is set to 27.12 MHz, and the electrical length of the resonant coil 212 is set to the length of one wavelength (approximately 11 meters).

[0043] The high-frequency power supply 273 includes a power control unit and an amplifier. The power control unit is configured to output a specified high-frequency signal (control signal) to the amplifier based on output conditions related to power and frequency preset via an operation panel. The amplifier is configured to output high-frequency power obtained by amplifying the control signal received from the power control unit to the resonant coil 212 via a transmission line. As described above, an RF sensor 272 is provided on the output side of the amplifier to detect reflected power in the transmission line and feed its voltage signal back to the frequency matching unit 274.

[0044] Frequency matcher 274 receives a voltage signal related to the reflected wave power from RF sensor 272 and performs correction control to increase or decrease the frequency (oscillation frequency) of the high-frequency power output by high-frequency power source 273 in a manner that minimizes the reflected wave power. The oscillation frequency correction is performed using a frequency control circuit within frequency matcher 274. The frequency control circuit is configured to oscillate at the no-load resonant frequency of resonant coil 212 before plasma ignition and at a preset frequency (the frequency after increasing or decreasing the no-load resonant frequency) in a manner that minimizes the reflected wave power after plasma ignition. The frequency control circuit feeds back a control signal, including the corrected frequency, to high-frequency power source 273. High-frequency power source 273 corrects the frequency of the high-frequency power based on this control signal. The frequency of the high-frequency power is optimized to the resonant frequency at which the reflected wave power in the transmission line becomes zero.

[0045] Using the above configuration, the induced plasma excited within the plasma generation space 201a becomes a high-quality plasma with almost no capacitive coupling to the inner wall of the processing chamber 201, the liner 217, etc. Within the plasma generation space 201a, a plasma with extremely low electrical potential and appearing ring-shaped when viewed from above is generated. In this embodiment, where the electrical length of the resonant coil 212 is set to one wavelength of the high-frequency power, such a ring-shaped plasma is generated near a height position corresponding to the electrical midpoint of the resonant coil.

[0046] like Figure 3As shown, the controller 221, serving as the control unit, is configured as a computer comprising a CPU (Central Processing Unit) 221a, RAM (Random Access Memory) 221b, a storage device 221c, and I / O ports 221d. The RAM 221b, storage device 221c, and I / O ports 221d are configured to exchange data with the CPU 221a via an internal bus 221e. Input / output devices 225 can be connected to the controller 221, such as a touch panel, mouse, keyboard, or operating terminal. A display unit, such as a monitor, can be connected to the controller 221.

[0047] The storage device 221c is composed of, for example, flash memory, HDD (Hard Disk Drive), CD-ROM, etc. Within the storage device 221c, control programs that control the operation of the substrate processing apparatus 100 and process flow diagrams describing substrate processing steps and conditions are stored in a readable manner. The process flow diagram functions as a program, combining the steps in the substrate processing process described later by the controller 221 to obtain a predetermined result. RAM 221b is configured as a memory area (working area) that temporarily holds programs, data, etc., read by the CPU 221a.

[0048] I / O port 221d is connected to the aforementioned MFC252a-252c, valves 253a-253c, 243a, 243b, gate valve 244, APC valve 242, vacuum pump 246, heater 217b, RF sensor 272, high-frequency power supply 273, frequency matcher 274, support lifting mechanism 268, impedance variable mechanism 275, etc.

[0049] CPU 221a is configured to read and execute control programs from storage device 221c, and to read process data from storage device 221c based on inputs such as operation commands from input / output device 225. For example... Figure 1As shown, CPU 221a is configured to control the opening adjustment of APC valve 242, the opening and closing of valve 243b, and the start and stop of vacuum pump 246 via I / O port 221d and signal line A, respectively, according to the read process information. It controls the lifting action of liner lifting mechanism 268 via signal line B, controls the power supply adjustment (temperature adjustment action) to heater 217b based on temperature sensor using heater power adjustment mechanism 276, and the impedance value adjustment action using impedance variable mechanism 275 via signal line C, controls the opening and closing action of gate valve 244 via signal line D, controls the operation of RF sensor 272, frequency matcher 274, and high-frequency power supply 273 via signal line E, and controls the flow rate adjustment of various gases using MFCs 252a to 252c and the opening and closing action of valves 253a to 253c and 243a via signal line F.

[0050] (2) Substrate processing process

[0051] Using the substrate processing apparatus 100 described above as a step in the manufacturing process of a semiconductor device, an example of a substrate processing sequence for oxidizing a film formed on the surface of a wafer 200 that serves as a substrate will be described. In the following description, the operation of each part constituting the substrate processing apparatus 100 is controlled by the controller 221.

[0052] The substrate processing sequence in this method includes the following steps:

[0053] Step A: The wafer 200 with a silicon oxide film (SiO film) formed on its surface is moved into the processing container 203;

[0054] Step B involves plasma-plating a mixture of He gas (a rare gas) and O2 gas (an oxygen-containing gas) to generate a reaction species containing oxygen and He (i.e., a reaction species containing rare gas elements); and,

[0055] Step C involves supplying the oxygen-containing reactants and the He reactants together to the wafer 200 to oxidize the SiO film.

[0056] In step B, the partial pressure P of the rare gas in the processing container 203 is reduced. N Relative to the total pressure P of the mixed gas T The ratio, i.e., the partial pressure ratio P, is... N / P T Sizes below 0.4.

[0057] It should be noted that the substrate processing sequence in this method is illustrated with the following example: In step B, in addition to O2 gas, H2 gas, which is H gas, is added as an O-containing gas.

[0058] When the term "wafer" is used in this specification, it may refer to the wafer itself, or it may refer to a laminate such as a specified layer or film formed on the wafer and its surface. When the term "surface of the wafer" is used in this specification, it may refer to the surface of the wafer itself, or it may refer to the surface of a specified layer, etc., formed on the wafer. When it is described as "forming a specified layer on the wafer," it may refer to forming the specified layer directly on the surface of the wafer itself, or it may refer to forming the specified layer on top of a layer, etc., formed on the wafer. When the term "substrate" is used in this specification, it is synonymous with the use of the term "wafer."

[0059] (Chip loading)

[0060] With the support 217 lowered to the designated transfer position, the gate valve 244 is opened, and the wafer 200 to be processed is transferred into the processing container 203 via a transfer mechanism (not shown) (step A). ​​The wafer 200 transferred into the processing container 203 is supported horizontally by three support pins 266 protruding upward from the substrate mounting surface 217d of the support 217. After the wafer 200 has been transferred into the processing container 203, the arm of the transfer mechanism is retracted from the processing container 203, and the gate valve 244 is closed. Then, the support 217 is raised to the designated processing position, and the wafer 200 to be processed is transferred from the support pins 266 onto the support 217.

[0061] A SiO film, which is the target of modification (oxidation), is pre-formed on the wafer 200. The SiO film is formed, for example, by depositing SiO on the wafer 200 at a relatively low temperature, such as room temperature to 600°C, preferably 100 to 500°C, using methods such as CVD or ALD. SiO films formed at such lower temperatures tend to contain more impurities and have a lower film density compared to SiO films formed at higher temperatures. The impurities tend to include at least one selected from the group consisting of hydrogen (H), oxygen (O), water (H₂O), carbon (C), nitrogen (N), phosphorus (P), sulfur (S), fluorine (F), and chlorine (Cl). SiO films containing a large number of impurities and having a low film density typically exhibit a high wet etching rate (WER) to aqueous solutions of hydrogen fluoride (HF), i.e., low wet etching resistance.

[0062] (Pressure regulation, temperature regulation)

[0063] Next, vacuum pump 246 is used to exhaust air from the processing container 203 to bring it to the desired processing pressure. The pressure inside the processing container 203 is measured by a pressure sensor, and the APC valve 242 is controlled based on the measured pressure information. Furthermore, the wafer 200 is heated using heater 217b to bring it to the desired processing temperature. After the processing container 203 reaches the desired processing pressure and the temperature of the wafer 200 reaches and stabilizes at the desired processing temperature, the oxidation process described later begins.

[0064] (Oxidation treatment)

[0065] In this process, a mixed gas containing He, O2, and H2 is supplied to the processing container 203 and plasma-generated to generate reaction species containing O and He (step B). Specifically, valves 253a-253c are opened, and while the flow is controlled using MFCs 252a-252c, the He, O2, and H2 gases are supplied to the processing chamber 201 via buffer chamber 237 while being mixed. At this time, high-frequency power is supplied to the resonant coil 212 from the high-frequency power supply 273. As a result, an induced plasma, which appears as a ring when viewed from above, is excited at a height corresponding to the electrical midpoint of the resonant coil 212 within the plasma generation space 201a.

[0066] The O2 and H2 gases in the mixed gas are activated (excited) and react through stimulation by induced plasma, generating O-containing reaction species within the processing container 203. These O-containing reaction species contain excited O atoms (O atoms in an excited state). ＊ The mixture contains at least one of ionized O atoms and OH radicals. Additionally, He gas in the mixture is activated by inductive plasma excitation, generating He reaction species within the processing container 203. The He reaction species includes excited He atoms (He... ＊ ), and at least one of the ionized He atoms.

[0067] In step B, the generated O-containing reactants and He-containing reactants, along with He gas, are supplied to wafer 200. As a result, the SiO film previously formed on the surface of wafer 200 is modified (oxidized) (step C). Because the O-containing reactants possess very high energy, impurities such as H, H₂O, C, N, P, S, F, and Cl in the target SiO film are removed from the SiO film. The O supplied to the SiO film, the O contained in the SiO film, and the unconnected Si bonds generated in the SiO film due to impurity removal combine to form new Si-O bonds in the SiO film. In this way, compared to the unmodified SiO film, the target SiO film has less impurity content and more Si-O bonds, resulting in a high-purity and dense SiO film. Compared to the unmodified SiO film, the modified SiO film has a low WER (Wet Errone) to HF aqueous solutions, i.e., high resistance to wet etching.

[0068] Examples of processing conditions in steps B and C can be shown below:

[0069] He gas supply flow rate: 0.01~5 slm, preferably 0.1~1 slm

[0070] O2 gas supply flow rate: 0.01–5 slm, preferably 0.1–1 slm

[0071] H2 gas supply flow rate: 0.01–5 slm, preferably 0.1–1 slm

[0072] Gas supply time: 0.2–60 minutes, preferably 0.5–10 minutes.

[0073] High-frequency power: 100–5000W, preferably 500–3500W

[0074] Processing temperature: room temperature to 1000℃, preferably 600 to 900℃, more preferably 700 to 800℃

[0075] Processing pressure: 1–250 Pa, more preferably 30–150 Pa

[0076] The distance from the plasma generation space to the substrate surface is 10–200 mm, preferably 30–100 mm.

[0077] In particular, by setting the processing pressure to 30 Pa or higher, it is possible to suppress splashing onto the inner wall of the processing container 203 under these processing conditions.

[0078] It should be noted that the "distance from the plasma generation space to the substrate surface" mentioned above refers to the distance from the lower end of the resonant coil 212 to the surface of the wafer 200.

[0079] Furthermore, the numerical range "10 to 5000 sccm" in this specification refers to "more than 10 sccm and less than 5000 sccm". The same applies to other numerical ranges.

[0080] The He supplied to the wafer 200 along with the O-containing reactants serves the following purposes during the period from the plasma generation space 201a (especially at a height corresponding to the electrical midpoint of the resonant coil 212 that generates the induced plasma) to reaching the surface of the wafer 200: it activates the O-containing gas to further generate the O-containing reactants; or it activates the O-containing reactants to prevent deactivation. That is, during the period until the O-containing reactants reach the surface of the wafer 200, the He supplied to the wafer 200 helps maintain or increase the density of the O-containing reactants.

[0081] Furthermore, He, supplied to the wafer 200 along with the O-containing reactants, is an element with a very small atomic radius. Therefore, the He reactants deeply penetrate (permeate) into the interior of the SiO film to be modified, spreading throughout the entire thickness direction of the SiO film. The He reactants penetrating into the SiO film function to prevent the deactivation of the O-containing reactants in the film and to enhance the aforementioned modification effect in the film using the O-containing reactants. Therefore, when He reactants are supplied together with the O-containing reactants, the oxidation treatment of the SiO film using the aforementioned O-containing reactants can be effectively assisted, enabling reliable oxidation of the entire area of ​​the SiO film. The oxidation treatment in this method occurs not only on the surface of the SiO film but also, for example, throughout the entire thickness direction of the SiO film.

[0082] The effect of maintaining the density of the O-containing reactants and the oxidation-assisted effect (modification-assisted effect) (hereinafter, both effects are referred to as oxidation-assisted effect) described herein, resulting from the supply of O-containing reactants together with He, are obtained by adding a predetermined amount of He gas to the mixed gas during steps B and C. That is, the aforementioned modification effect, which reduces the WER of the SiO film, is achieved by adjusting the partial pressure P of the He gas within the processing container 203. N The total pressure P relative to the mixed gas (He, O2, H2) T The ratio, i.e., P N / P T It is obtained by setting a size greater than 0.

[0083] Figure 4 The WER of the modified SiO film is schematically illustrated with respect to the partial pressure ratio P mentioned above in step B. N / P T The relationship between their sizes. Specifically, Figure 4The vertical axis shows the WER[au] of the modified SiO film. Figure 4 The horizontal axis represents P in step B, indicated by [%]. N / P T The size of P. In the diagram, P is referred to as P. N / P T =0 means that in step B, O2 gas and H2 gas are supplied to the processing container 203 respectively, but He gas is not supplied to the processing container 203 (only O2 + H2). Additionally, the so-called P... N / P T =100 means that in step B, He gas is supplied to the processing container 203, but O2 gas and H2 gas are not supplied to the processing container 203 respectively (only He).

[0084] like Figure 4 As shown, by P N / P T Setting the value to a value greater than 0 allows for the aforementioned oxidation-assisted effect resulting from the combined supply of O-containing reactants and He reactants. Consequently, the WER of the modified SiO film can be reduced, i.e., its wet etching resistance can be improved. Specifically, the WER of the modified SiO film obtained by sequentially performing steps B and C can be made to be a value lower than that of the SiO film (hereinafter also referred to as SiO film X) obtained by supplying O-containing reactants separately to the wafer 200 in the processing container 203 without supplying He reactants in step C. It should be noted that by using P N / P T Setting the value to 0.02 [2%] or higher significantly improves the oxidation-assisted effect resulting from the supply of reactants containing O and reactants containing He, thereby reducing the WER of the modified SiO film. Furthermore, by using P... N / P T Setting the value to 0.04 [4%] or higher, the aforementioned oxidation-assisted effect resulting from the combined supply of reactants containing O and reactants containing He can be reliably obtained, and the WER of the modified SiO film can be reliably reduced.

[0085] However, as Figure 4 As shown, P N / P TWhen the value exceeds 0.6 [60%], the following situation occurs: it is difficult to obtain the aforementioned oxidation-assisted effect resulting from the supply of reactants containing O along with reactants containing He, that is, the effect of reducing the WER of the modified SiO film. Specifically, the following situation occurs: the WER of the modified SiO film obtained by sequentially performing steps B and C is greater than that of the SiO film X obtained by supplying reactants containing O alone to the wafer 200 in the processing container 203 in step C without supplying reactants containing He. By P N / P T By setting the value to 0.6 [60%] or less, the aforementioned oxidation-assisted effect resulting from the combined supply of O-containing reactants and He reactants can be obtained, resulting in a WER of the modified SiO film that is lower than that of SiO film X. By using P N / P T By setting the value to 0.4 [40%] or less, the aforementioned oxidation-assisted effect resulting from the supply of reactants containing O along with reactants containing He can be reliably obtained, resulting in a reliable reduction in the WER of the modified SiO film. By using P N / P T Setting the value to 0.2 [20%] or less allows for more reliable acquisition of the aforementioned oxidation-assisted effect resulting from the supply of reactants containing O and reactants containing He, and as a result, allows for a more reliable reduction in the WER of the modified SiO film.

[0086] Based on the above, preferably, in step B, the partial pressure P of the He gas in the processing container 203 is... N The total pressure P relative to the mixed gas (He, O2, H2) T The ratio, i.e., P N / P T The value is set to a value greater than 0 and less than 0.6, preferably between 0.01 and 0.4, and more preferably between 0.05 and 0.2. It should be noted that the partial pressure ratio P... N / P T The size can be adjusted, for example, by controlling the flow rate of He gas supplied to the processing container 203 and the ratio of the total flow rate of O2 gas and H2 gas supplied to the processing container 203 in step B.

[0087] Furthermore, in order to obtain the aforementioned oxidation-assisted effect resulting from the supply of O-containing reactants along with He, the distance from the plasma generation space to the substrate surface needs to be set to a distance at which at least a portion of the He reactants reaches the substrate surface without deactivation. In this embodiment, for example, by setting this distance to 10–200 mm, preferably 30–100 mm, the required flow rate of He reactants to obtain the aforementioned oxidation-assisted effect is supplied to the substrate surface. Moreover, the magnitude of the aforementioned oxidation-assisted effect can be adjusted by changing this distance. For example, by increasing the distance, the aforementioned oxidation-assisted effect can be reduced.

[0088] In addition to He, other rare gases such as Ar, Ne, and Xe can also be used as rare gases.

[0089] In addition to O2, other oxygen-containing gases that do not contain hydrogen, such as ozone (O3), water vapor (H2O), nitric oxide (NO), and nitrous oxide (N2O), can also be used as oxygen-containing gases.

[0090] In addition to H2 gas, deuterium (D2) gas can also be used as a gas containing H.

[0091] (Post-purging and atmospheric pressure recovery)

[0092] After the above modification treatment is completed, the supply of He gas, O2 gas, and H2 gas to the treatment container 203 is stopped, and the supply of high-frequency power to the resonant coil 212 is also stopped. Then, N2 gas, used as a purge gas, is supplied to the treatment container 203 and exhausted from the exhaust pipe 231. As a result, the treatment container 203 is purged, and the gases and reaction byproducts remaining in the treatment container 203 are removed. Then, the atmosphere in the treatment container 203 is replaced with N2 gas, and the pressure in the treatment container 203 is restored to atmospheric pressure.

[0093] (Chip removal)

[0094] Next, the support 217 is lowered to the designated transport position, and the wafer 200 is transferred from the support 217 to the support pin 266. Then, the gate valve 244 is opened, and using a transport mechanism (not shown), the processed wafer 200 is moved out of the processing container 203. The above steps complete the substrate processing steps involved in this method.

[0095] (3) Effects of this method

[0096] According to this method, one or more of the following effects can be obtained.

[0097] (a) By performing steps B and C, the aforementioned impurities contained in the unmodified SiO film can be removed from the film. Furthermore, the modified SiO film can be made to have a higher content of Si-O bonds and be more dense than the unmodified SiO film. As a result, for example, the properties of the modified SiO film can be improved, such as making the wet etching resistance of the modified SiO film higher than that of the unmodified SiO film.

[0098] (b) By generating reactants containing O and He in step B, and supplying the reactants containing O and He together to the wafer 200 in step C, the aforementioned oxidation-assisted effect resulting from the supply of reactants containing O and He together can be obtained. This improves the properties of the film, such as enhancing the wet etching resistance of the modified SiO film.

[0099] (c) By reducing the partial pressure P of the He gas in the processing container 203 in step B. N The total pressure P relative to the mixed gas (He, O2, H2) T The ratio, i.e., P N / P T By setting the value to a size greater than 0 and less than 0.6, the oxidation-assisted effect resulting from the supply of reactants containing O along with reactants containing He can be obtained. This further improves the wet etching resistance of the modified SiO film. It should be noted that by using P... N / P T Setting the value to between 0.02 and 0.4 yields significant results regarding the effects described here, by making P... N / P T A size between 0.04 and 0.2 is sufficient to reliably achieve the effects described herein.

[0100] (d) In step B, by adding H2 gas to the O2 gas, an improved oxidizing power can be obtained compared to the case where O2 gas, which is an O-containing gas, is supplied alone. This improves the properties of the modified SiO film, such as its resistance to wet etching.

[0101] (e) By using He gas, which has a small atomic radius and extremely high permeability in the film, as a rare gas, the aforementioned oxidation-assisted effect can be obtained, for example, throughout the entire thickness direction of the SiO film. This improves the properties of the modified SiO film, such as enhancing its resistance to wet etching.

[0102] (f) The same effects can be obtained when using a noble gas other than He, an O-containing gas other than O2, or a H-containing gas other than H2. A preferred aspect is that, compared to using a noble gas other than He, using He as the noble gas results in a smaller atomic radius, thus more reliably achieving the aforementioned effects. When using a noble gas other than He, it is preferable to use it in combination with He. That is, for the noble gas, it is preferable to contain at least He.

[0103] (4) Variations

[0104] The substrate processing sequence in this method is not limited to the above-described method and can be modified as shown in the following variations. These variations can be combined arbitrarily. Unless otherwise specified, the processing steps and conditions in each step of each variation can be the same as the processing steps and conditions in each step of the above-described substrate processing sequence.

[0105] (Variation Example 1)

[0106] In steps B and C, it is not limited to adding H2 gas to O2 gas; O2 gas or other gases can also be used alone as the O-containing gas. In this case, the same effect as the substrate treatment sequence described above can be obtained. Among these, from the perspective of obtaining an effect that improves oxidation power, it is preferable to add H2 gas to the O2 gas, which is an O-containing gas.

[0107] (Variation Example 2)

[0108] The modified film pre-formed on wafer 200 is not limited to SiO film, but can also be other films containing elements other than Si. For example, the modified film can be a film containing Si and N, i.e., a silicon nitride film (SiN film), or a film containing Si, O, and N, i.e., a silicon oxynitride film (SiON film). Alternatively, the modified film can also be a Si film formed from elemental Si. In these cases, the same effect as the substrate processing sequence described above can be obtained.

[0109] <Other methods>

[0110] The above details the format of this disclosure. However, this disclosure is not limited to the above format and may be modified in various ways without departing from its intent.

[0111] For example, the above description addresses an example where the film of the modified object is directly formed on a substrate, i.e., the substrate of the film of the modified object is the surface of the substrate (an example of a Si single crystal). However, this disclosure is not limited to such an approach. For example, the substrate of the film of the modified object can be a film formed on a substrate. Examples of such films include Si films, SiO films, SiN films, and SiON films. In such cases, the same effect as described above can be obtained by performing the same substrate processing sequence as described above.

[0112] Furthermore, for example, the above description focuses on the plasma treatment of a mixture of rare gas and O-containing gas within a processing container, but this disclosure is not limited to this method. That is, the plasma treatment of the mixed gas can be performed outside the processing container, and the O-containing reaction mixture generated outside the processing container, along with the rare gas, can be supplied into the processing container. Of these, the above-described method is preferred to fully obtain the aforementioned oxidation-assisted effect.

[0113] The above methods and variations can be used in appropriate combinations. The processing steps and conditions can be set to be the same as those in the methods described above.

[0114] Example

[0115] As sample 1, using Figure 1 The substrate processing apparatus shown oxidizes the SiO film formed on the wafer surface using the substrate processing sequence described above. In step B, the supply flow rates of He gas, O2 gas, and H2 gas into the processing container are set to 1 slm, 0.75 slm, and 0.75 slm respectively, and the aforementioned partial pressure ratio P is... N / P T Set to 0.4. Other processing conditions are the specified conditions within the range of processing conditions described above.

[0116] As sample 2, using Figure 1 The substrate processing apparatus shown oxidizes the SiO film formed on the surface of the wafer using the substrate processing sequence described above. In step B, the supply flow rates of He gas, O2 gas, and H2 gas into the processing container are set to 0.5 slm, 1 slm, and 1 slm respectively, and the aforementioned P... N / P T Set to 0.2. Other processing conditions are the specified conditions within the range of processing conditions described above, and are common to the processing conditions in Sample 1.

[0117] As sample 3, using Figure 1The substrate processing apparatus shown oxidizes the SiO film formed on the surface of the wafer. When preparing sample 3, He gas is not supplied to the processing container, and the supply flow rates of O2 gas and H2 gas are set to 1.25 slm and 1.25 slm, respectively. The aforementioned P... N / P T Set to 0. Other processing conditions are the specified conditions within the range of processing conditions described above, and are the same as the processing conditions in Sample 1.

[0118] Then, the wet etching resistance of the oxidized SiO film was evaluated. Figure 5 The upper chart in the image represents samples 1 through 3 from left to right. Figure 5 The vertical axis of the upper chart represents the WER improvement rate [%). The WER improvement rate is defined as (R0-R1) / R0, where R0 is the WER of the unmodified SiO film relative to a 1% HF aqueous solution, and R1 is the WER of the modified SiO film. A higher WER improvement rate indicates a greater improvement in film quality (enhanced wet etching resistance) due to the oxidation treatment.

[0119] like Figure 5 As shown, it can be seen that compared to P N / P T Sample 3 with a value of 0, P N / P T Samples 1 and 2, with WER improvements below 0.4, exhibited greater resistance to wet etching. Furthermore, it is known that P... N / P T Sample 2 with a value of 0.2 compared to P N / P T For sample 1 with a value of 0.4, the WER improvement rate is greater, indicating higher resistance to wet etching. That is, it can be seen that by using P... N / P T Setting the value to between 0.01 and 0.4 achieves the aforementioned modification effect, by adjusting P... N / P T Setting P to a value below 0.2 can further improve the aforementioned modification effect. Furthermore, it is known that by... N / P T Setting the value to between 0.2 and 0.4 reliably achieves the aforementioned modification effect.

[0120] Explanation of reference numerals in the attached figures

[0121] 200 wafers (substrates)

[0122] 203 Processing Container

Claims

1. A method for manufacturing a semiconductor device, comprising the steps of: (a) a step of carrying a substrate having a film formed on a surface thereof into a processing vessel; (b) a step of generating reactive species containing oxygen and reactive species of a rare gas by plasma-activating a mixed gas containing the rare gas and an oxygen-containing gas; and (c) a step of supplying the reactive species containing oxygen and the reactive species of the rare gas to the substrate together to oxidize the film while suppressing deactivation of the reactive species containing oxygen by the reactive species of the rare gas infiltrating into an inside of the film, wherein a wet etching rate of the film after modification obtained by sequentially performing the steps (b) and (c) is lower than a wet etching rate of the film before modification obtained by sequentially performing the steps (b) and (c). In the step (b), a hydrogen-containing gas is added to the oxygen-containing gas and used.

6. The method for manufacturing a semiconductor device according to claim 5, wherein at least either one of an oxygen gas or an ozone gas is used as the oxygen-containing gas, at least either one of a hydrogen gas or a deuterium gas is used as the hydrogen-containing gas. wherein In the (b), the partial pressure P of the rare gas in the processing vessel is made 0.4 or less N with respect to the total pressure P of the mixed gas T The ratio, i.e., the partial pressure ratio P N / P T is set to 0.4 or less, and the size is selected within a range such that the wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) becomes lower than the wet etching rate of a film obtained by supplying only the reaction species containing oxygen to the substrate in the processing vessel without supplying the reaction species of the rare gas in the (b) In the step (b), a gas not containing hydrogen is used as the oxygen-containing gas.

2. The method for manufacturing a semiconductor device according to claim 1, wherein In the (b), the partial pressure ratio P N / P T is set to a size of 0.2 or less.

3. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein In the (b), the partial pressure ratio P N / P T is set to a size of 0.02 or more.

4. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein In the (b), the partial pressure ratio P N / P T is set to 0.04 or more.

5. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein In the step (b), a helium gas is used as the rare gas. The film formed on the surface of the substrate is a silicon-containing film. The film formed on the surface of the substrate is a silicon oxide film. The film formed on the surface of the substrate is a silicon nitride film.

7. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein The film formed on the surface of the substrate is a film containing at least one impurity selected from the group consisting of hydrogen, oxygen, moisture, carbon, nitrogen, phosphorus, sulfur, fluorine, and chlorine.

8. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein In the steps (b) and (c), the temperature of the substrate is 700°C or higher.

9. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein 15. A method for manufacturing a semiconductor device, comprising the steps of: (a) a step of carrying a substrate having a film formed on a surface thereof into a processing vessel; (b) a step of generating reactive species containing oxygen and reactive species of a rare gas by plasma-activating a mixed gas containing the rare gas and an oxygen-containing gas; and (c) a step of oxidizing the film by supplying the reactive species containing oxygen and the reactive species of the rare gas to the substrate together, 10. The method of manufacturing a semiconductor device according to Claim 9, wherein a wet etching rate of the film after modification obtained by sequentially performing the steps (b) and (c) is lower than a wet etching rate of the film before modification obtained by sequentially performing the steps (b) and (c).

11. The method of manufacturing a semiconductor device according to Claim 9, wherein 16. A substrate processing method, comprising the steps of: (a) a step of carrying a substrate having a film formed on a surface thereof into a processing vessel; (b) a step of generating reactive species containing oxygen and reactive species of a rare gas by plasma-activating a mixed gas containing the rare gas and an oxygen-containing gas; and (c) a step of oxidizing the film by supplying the reactive species containing oxygen and the reactive species of the rare gas to the substrate together while suppressing deactivation of the reactive species containing oxygen by the reactive species of the rare gas infiltrating into an inside of the film, 12. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein ​ 13. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein In the (b), the P is adjusted by controlling the ratio of the flow rate of the rare gas supplied into the processing vessel to the flow rate of the oxygen-containing gas supplied into the processing vessel. N / P T value.

14. The method of manufacturing a semiconductor device according to Claim 1 or 2, wherein ​ ​ ​ ​ ​ wherein In the (b), the partial pressure P of the rare gas in the processing vessel is selected within a range where N the total pressure P of the mixed gas T the ratio P N / P T , that is, so that the wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) becomes within a range below the wet etching rate of a film obtained by supplying only the reaction species containing oxygen to the substrate in the processing vessel without supplying the reaction species of the rare gas in the (b), ​ ​ ​ ​ ​ wherein In the (b), the partial pressure P of the rare gas in the processing vessel is set to 0.4 Pa or less N with respect to the total pressure P of the mixed gas T The ratio, i.e., the partial pressure ratio P N / P T is set to 0.4 Pa or less, and the size is selected within a range such that the wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) becomes lower than the wet etching rate of a film obtained by supplying only the reaction species containing oxygen to the substrate in the processing vessel without supplying the reaction species of the rare gas in the (b) wherein a wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) is less than a wet etching rate of the film before modification obtained by sequentially performing the (b) and the (c).

17. A computer-readable recording medium recording a program for causing a substrate processing apparatus to execute the steps of: (a) a step of carrying a substrate on which a film is formed into a processing vessel of a substrate processing apparatus; (b) a step of generating reaction species containing oxygen and reaction species of a rare gas by plasma-izing a mixed gas containing the rare gas and an oxygen-containing gas; and (c) a step of supplying the reaction species containing oxygen and the reaction species of the rare gas to the substrate together, and oxidizing the film while suppressing deactivation of the reaction species containing oxygen by the reaction species of the rare gas that penetrates into the inside of the film; and In the (b), the partial pressure P of the rare gas in the processing vessel is N The ratio, i.e. the partial pressure ratio P T The ratio, i.e. the partial pressure ratio P N / P T is set to 0.4 or less, and the size is selected from a range in which the wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) becomes lower than the wet etching rate of a film obtained by supplying only the reaction species containing oxygen to the substrate in the processing vessel without supplying the reaction species of the rare gas in the (b), and making a wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) less than a wet etching rate of the film before modification obtained by sequentially performing the (b) and the (c).

18. A substrate processing apparatus having: a processing vessel that accommodates a substrate; a conveyance system that carries a substrate into the processing vessel; a first supply system that supplies a rare gas into the processing vessel; a second supply system that supplies an oxygen-containing gas into the processing vessel; a plasma generation section that plasma-izes a gas supplied into the processing vessel; an exhaust system that exhausts the inside of the processing vessel; and a control section configured to be capable of controlling the conveyance system, the first supply system, the second supply system, the plasma generation section, and the exhaust system to perform the following processing: (a) a process of carrying into the processing vessel a substrate on which a film is formed; (b) a process of generating reaction species containing oxygen and reaction species of the rare gas by plasma- izing a mixed gas containing the rare gas and the oxygen-containing gas; and (c) a process of supplying the reaction species containing oxygen together with the reaction species of the rare gas to the substrate, oxidizing the film while suppressing deactivation of the reaction species containing oxygen by the reaction species of the rare gas infiltrating into the inside of the film; and in the (b), the partial pressure P N of the rare gas in the processing vessel is set to 0.4 or less, and the ratio, i.e., the partial pressure ratio P T of the rare gas to the total pressure P N of the mixed gas is set to 0.4 or less. T The process is set to a size of 0.4 or less, and is selected from a range in which a wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) becomes a wet etching rate of a film obtained by supplying only the reaction species containing oxygen to the substrate in the processing vessel without supplying the reaction species of the rare gas in the (b). making a wet etching rate of the modified film obtained by sequentially performing the (b) and the (c) less than a wet etching rate of the film before modification obtained by sequentially performing the (b) and the (c).

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