Substrate processing method, semiconductor device manufacturing method, substrate processing apparatus, and recording medium

Abstract

The present invention relates to a substrate processing method, a semiconductor device manufacturing method, a substrate processing apparatus, and a computer-readable recording medium. Provided is a technology capable of modifying the surface of a substrate into an oxide layer having a desired thickness and excellent characteristics even under low-temperature conditions. Provided is a technology having (a) a step of supplying a reaction species, which is generated by plasma excitation of a first processing gas containing oxygen and hydrogen at a first ratio of hydrogen to oxygen, to a substrate to modify the surface of the substrate into a first oxide layer, and (b) a step of supplying a reaction species, which is generated by plasma excitation of a second processing gas containing oxygen and hydrogen at a second ratio of hydrogen to oxygen that is smaller than the first ratio, to the substrate to modify the first oxide layer into a second oxide layer.

Description

Technical Field

[0001] This disclosure relates to substrate processing methods, semiconductor device manufacturing methods, substrate processing apparatus, and recording media. Background Technology

[0002] As a step in the manufacturing process of semiconductor devices, the following process is sometimes performed: using a gas excited by plasma to modify the surface of a film formed on a substrate into an oxide layer (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2016 / 125606 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The purpose of this disclosure is to provide a technique for modifying the surface of a substrate into an oxide layer of desired thickness with excellent properties, even under low-temperature conditions.

[0008] Methods for solving problems

[0009] According to one aspect of this disclosure, the following technology is provided, which has:

[0010] (a) A process of modifying (oxidizing) the surface of a substrate into a first oxide layer by supplying a reaction seed to the substrate, wherein the reaction seed is generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and

[0011] (b) A process of supplying the substrate with the following reaction seed to modify the first oxide layer into a second oxide layer, wherein the reaction seed is generated by plasma excitation of a second processing gas containing oxygen and hydrogen, wherein the ratio of hydrogen to oxygen is less than the first ratio.

[0012] The effects of the invention

[0013] According to this disclosure, even at low temperatures, the surface of a substrate can be modified into an oxide layer of desired thickness with excellent properties. Attached Figure Description

[0014] [ Figure 1 [This is a schematic configuration diagram of a substrate processing apparatus 100 preferably used in one embodiment of the present disclosure, and is a diagram showing the processing furnace 202 portion in a longitudinal cross-sectional view.]

[0015] [ Figure 2[Illustrative diagram illustrating the plasma generation principle in a substrate processing apparatus 100 preferred in one embodiment of this disclosure.]

[0016] [ Figure 3 [This is a schematic configuration diagram of the controller 221 provided in the substrate processing apparatus 100 preferred in one embodiment of the present disclosure, and is a block diagram showing the control system of the controller 221.]

[0017] [ Figure 4 This is a graph showing the relationship between the ratio of hydrogen in the processing gas at various processing temperatures and the thickness of the oxide layer formed by the modification treatment.

[0018] [ Figure 5 This is a graph showing the relationship between the processing temperature and the thickness of the oxide layer formed by the modification process at various ratios of hydrogen contained in the processing gas.

[0019] [ Figure 6 [This is a schematic configuration diagram of a substrate processing apparatus 100' preferred in one embodiment of the present disclosure, and is a diagram showing a portion of the processing furnace 202 in a longitudinal sectional view.]

[0020] Explanation of reference numerals in the attached figures

[0021] 200 wafers (substrates)

[0022] 201 Processing Room

[0023] 212 Resonant Coil

[0024] 250a Hydrogen-containing gas supply source

[0025] 250b Oxygen-containing gas supply source Detailed Implementation

[0026] <One way of publishing this text>

[0027] The following is mainly based on Figures 1-5 This disclosure will be described in one manner. It should be noted that the accompanying drawings used in the following description are schematic, and the dimensional relationships and ratios of the elements shown in the drawings may not necessarily correspond to actual dimensions. Furthermore, the dimensional relationships and ratios of elements may not necessarily be consistent across multiple drawings.

[0028] (1) Composition of substrate processing device

[0029] like Figure 1As shown, the substrate processing apparatus 100 includes a processing furnace 202 for plasma processing of a wafer 200, which serves as a substrate. The processing furnace 202 includes a processing container 203 constituting a processing chamber 201. The processing container 203 includes a dome-shaped upper container 210 as a first container and a bowl-shaped lower container 211 as a second container. The processing chamber 201 is formed by covering the lower container 211 with the upper container 210. The upper container 210 is made of a non-metallic material such as alumina (Al₂O₃) or quartz (SiO₂), and the lower container 211 is made of, for example, aluminum (Al).

[0030] 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 the processing chamber 201 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.

[0031] like Figure 2 As 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 used for processing the wafer 200. 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 Compared to the single-dotted line in the image, the space is located further above. On the other hand, the substrate processing space 201b is the space where the substrate is processed by plasma, and refers to the space located further below the lower end of the resonant coil 212.

[0032] At the center of the bottom side of the processing chamber 201, a support 217 is disposed as a substrate mounting part for mounting the wafer 200. The support 217 is made of non-metallic materials such as aluminum nitride (AlN), ceramic, or quartz.

[0033] Inside the support 217, a heater 217b, which serves as a heating mechanism, is integrally embedded. By supplying power to the heater 217b via the heater power regulating mechanism 276, the surface of the wafer 200 can be heated to a specified temperature within the range of, for example, 25 to 1000°C.

[0034] 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, and the capacitance of the variable capacitor, the impedance of the impedance adjustment electrode 217c can be varied within a specified range from approximately 0 Ω to the parasitic impedance value of the processing chamber 201. Therefore, the potential (bias voltage) of the wafer 200 during plasma processing can be controlled via the impedance adjustment electrode 217c and the support 217.

[0035] A support lifting mechanism 268 is provided below the support 217 to raise and lower the support. A through hole 217a is provided in the support 217. A support pin 266, serving as a support for the wafer 200, is provided on the bottom surface of the lower container 211. At least three through holes 217a and support pins 266 are provided at positions opposite to each other. When the support 217 is lowered using the support lifting mechanism 268, the support pins 266 pass through the through hole 217a without contacting the support 217. This allows the wafer 200 to be held from below.

[0036] A gas supply head 236 is provided above the processing chamber 201, specifically at the upper part of the upper container 210. The gas supply head 236 is configured to include 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, enabling it to supply gas into the processing chamber 201. The buffer chamber 237 functions as a dispersion space to disperse the reactive gas introduced through the gas inlet 234.

[0037] The downstream end of a gas supply pipe 232a supplying hydrogen-containing gas (H), the downstream end of a gas supply pipe 232b supplying oxygen-containing gas (O), and a gas supply pipe 232c supplying inert gas are connected to a gas inlet 234 in a confluence manner. On gas supply pipe 232a, starting from the upstream side, a hydrogen-containing gas supply source 250a, a mass flow controller (MFC) 252a (as a flow control device), and a valve 253a (as an on / off valve) are sequentially arranged. On gas supply pipe 232b, starting from the upstream side, an oxygen-containing gas supply source 250b, an MFC 252b (as a flow control device), and a valve 253b (as an on / off valve) are sequentially arranged. On gas supply pipe 232c, starting from the upstream side, an inert gas supply source 250c, an MFC 252c (as a flow control device), and a valve 253c (as an on / off valve) are sequentially arranged. A valve 243a is provided downstream of the confluence of gas supply pipes 232a, 232b, and 232c, and is connected to the upstream end of the gas inlet 234. By opening and closing valves 253a-253c and 243a, the flow rates of each gas can be adjusted using MFCs 252a-252c, and hydrogen-containing gas, oxygen-containing gas, and inactive gas can be supplied to the processing chamber 201 via gas supply pipes 232a, 232b, and 232c.

[0038] The hydrogen-containing gas supply system mainly consists of a gas supply head 236 (cover 233, gas inlet 234, buffer chamber 237, opening 238, shielding plate 240, and gas outlet 239), a gas supply pipe 232a, an MFC 252a, and valves 253a and 243a. Additionally, the oxygen-containing gas supply system mainly consists of a gas supply head 236, a gas supply pipe 232b, an MFC 252b, and valves 253b and 243a. Furthermore, the inactive gas supply system mainly consists of a gas supply head 236, a gas supply pipe 232c, an MFC 252c, and valves 253c and 243a.

[0039] 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.

[0040] The exhaust section mainly consists of exhaust port 235, exhaust pipe 231, APC valve 242, and valve 243b. The vacuum pump 246 may also be included in the exhaust section.

[0041] 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, to surround the processing chamber 201. 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.

[0042] 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 power monitored by the RF sensor 272.

[0043] The two 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, which can be arbitrarily set to receive power from the high-frequency power supply 273.

[0044] The excitation section (plasma generation section) mainly consists of a resonant coil 212, an RF sensor 272, and a frequency matcher 274. The excitation section excites the gas supplied to the processing chamber 203 (plasma generation space 201a) from the hydrogen gas supply system and the oxygen gas supply system. Alternatively, a high-frequency power supply 273 and a shielding plate 223 may be included in the excitation section.

[0045] The following uses Figure 2 The operation of the excitation unit and the properties of the generated plasma are explained in detail.

[0046] 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 resonate in 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 considering the shape of the substrate processing apparatus 100 and the processing requirements. As an example, the coil diameter of the resonant coil 212 is set to 200–500 mm, and the number of turns is set to 2–60.

[0047] 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.

[0048] The frequency matcher 274 receives a voltage signal related to the reflected wave power from the RF sensor 272 and performs correction control to increase or decrease the frequency (oscillation frequency) of the high-frequency power output by the high-frequency power supply 273 in a manner that minimizes the reflected wave power.

[0049] 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 potential and a ring-shaped appearance when viewed from above is generated.

[0050] like Figure 3 As 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, such as touch panels, mice, keyboards, and operating terminals, can be connected to the controller 221. A display unit, such as a monitor, can also be connected to the controller 221.

[0051] Storage device 221c is configured with, for example, flash memory, HDD (Hard Disk Drive), CD-ROM, etc. Within storage device 221c, control programs for controlling the operation of substrate processing apparatus 100 and process recipes describing substrate processing steps, conditions, etc., are stored in a readable manner. The process recipe functions as a program, combining steps in the substrate processing process described later by a controller 221 configured as a computer to execute the substrate processing apparatus 10 and obtain a predetermined result. Hereinafter, the process recipe, control program, etc., will be collectively referred to as a program. It should be noted that when the term "program" is used in this specification, it may refer only to the process recipe itself, only to the control program itself, or both. RAM 221b is configured as a memory area (working area) for temporarily storing programs, data, etc., read by CPU 221a.

[0052] I / O port 221d is connected to the aforementioned MFCs 252a-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.

[0053] CPU 221a is configured to read and execute control programs from storage device 221c, and to read process technology from storage device 221c based on inputs such as operation commands from input / output device 225. Furthermore, as... Figure 1 As shown, CPU 221a is configured to, according to the read process information, 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; control the lifting action of liner lifting mechanism 268 via signal line B; control the power supply adjustment action (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; control the opening and closing action of gate valve 244 via signal line D; control the operation of RF sensor 272, frequency matcher 274, and high-frequency power supply 273 via signal line E; and control the flow rate adjustment action 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.

[0054] It should be noted that the controller 221 is not limited to being configured as a dedicated computer, but can also be configured as a general-purpose computer. For example, by preparing an external storage device (e.g., magnetic tape, floppy disk, hard disk, CD, DVD, MO, USB memory, memory card, etc.) 226 storing the aforementioned program, and using the external storage device 226 to install programs on a general-purpose computer, the controller 221 according to this embodiment can be configured. It should be noted that the means for supplying programs to the computer is not limited to supplying them through the external storage device 226. For example, communication means such as networks or dedicated lines can be used to supply programs without using the external storage device 226. It should be noted that the storage device 221c and the external storage device 226 are configured as computer-readable recording media. Hereinafter, they will also be collectively referred to as recording media. It should be noted that in this specification, the term "recording media" may include only the storage device 221c itself, only the external storage device 226 itself, or both.

[0055] (2) Substrate processing process

[0056] 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 processing a wafer 200, which serves as a substrate, will be described. Specifically, an example of a sequence for surface modification of a film formed on the surface of the wafer 200 to form an oxide layer will be described. In the following description, the operation of each part constituting the substrate processing apparatus 100 is controlled by the controller 221.

[0057] In the substrate processing sequence of this method, the following steps are performed:

[0058] Step a involves supplying the following reaction seed to the wafer 200 to modify (oxidize) the surface of the wafer 200 into a first oxide layer, wherein the reaction seed is generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and

[0059] Step b involves supplying the following reaction seed to the wafer 200 to modify the first oxide layer into a second oxide layer. This reaction seed is generated by plasma excitation of a second processing gas containing oxygen and hydrogen, wherein the ratio of hydrogen to oxygen is less than the first ratio.

[0060] When the term "wafer" is used in this specification, it may refer to the wafer itself, or it may refer to a laminate of a wafer and a specified layer or film formed on the wafer's 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."

[0061] (Chip loading)

[0062] With the support 217 lowered to the designated transport position, gate valve 244 is opened, and the wafer 200 to be processed is transported into the processing chamber 201 by a transport robot (not shown). The wafer 200, transported into the processing chamber 201, is supported horizontally on support pins 266 protruding from the surface of the support 217. After the wafer 200 has been transported into the processing chamber 201, the arm of the transport robot is retracted from the processing chamber 201, and 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. It should be noted that the wafer transport can be performed while purging the processing chamber 201 with an inert gas or similar material.

[0063] It should be noted that, as an example, the surface of the wafer 200, which is the object of the modification treatment, is composed of a substrate of elemental Si (single-crystal Si, polycrystalline Si, or amorphous silicon). That is, as an example, the surface of the wafer 200 is composed of a substrate containing Si. Here, the term "substrate" includes, for example, the case of a film, or the case where the surface of the wafer, which serves as the substrate, is exposed.

[0064] (Pressure and temperature regulation)

[0065] Next, vacuum pump 246 is used to exhaust air from the processing chamber 201 to achieve the desired processing pressure. The pressure inside the processing chamber 201 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 by heater 217b to achieve the desired processing temperature. After the processing pressure inside the processing container 203 is reached and the temperature of the wafer 200 stabilizes at the desired processing temperature, the nitriding process (described later) begins. Vacuum pump 246 is operated until the wafer unloading process (described later) is completed.

[0066] Then, perform the following steps a and b in sequence.

[0067] [Step a: First oxide layer formation process]

[0068] In step a, the following steps are performed: step a-1, supplying oxygen-containing gas and hydrogen-containing gas into the processing chamber 201; and step a-2, plasma-exciting the gas containing oxygen-containing gas and hydrogen-containing gas supplied to the processing chamber 201, and supplying the reaction seed generated by plasma excitation to the wafer 200, thereby modifying (oxidizing) the surface of the wafer 200 into a first oxide layer.

[0069] Specifically, valve 253a is opened to allow hydrogen-containing gas to flow into gas supply pipe 232a, and valve 253b is opened to allow oxygen-containing gas to flow into gas supply pipe 232b. The flow rates of the hydrogen-containing gas and oxygen-containing gas are regulated by MFCs 252a and 252b, respectively, and supplied to the processing chamber 201 via buffer chamber 237, and exhausted from exhaust port 235. At this time, a mixture of hydrogen-containing gas and oxygen-containing gas (the first processing gas supply) is supplied to the processing chamber 201 as the first processing gas containing hydrogen and oxygen. It should be noted that at this time, valve 243c can be opened to simultaneously supply inactive gas to the processing chamber 201 via buffer chamber 237.

[0070] For example, hydrogen (H2) gas, deuterium (D2) gas, water vapor (H2O gas), hydrogen peroxide (H2O2) gas, etc., can be used as hydrogen-containing gases. More than one of them can be used as hydrogen-containing gases.

[0071] Examples of oxygen-containing gases that can be used include oxygen (O2), nitrous oxide (N2O), nitric oxide (NO), nitrogen dioxide (NO2), ozone (O3), water vapor (H2O), carbon monoxide (CO), and carbon dioxide (CO2). More than one of these gases can be used. It should be noted that when using hydrogen-containing gases such as H2O or H2O2 as oxygen-containing gases, it is preferable to use gases other than these as hydrogen-containing gases.

[0072] As inert gases, for example, rare gases such as N2, argon (Ar), helium (He), neon (Ne), and xenon (Xe) can be used. More than one of these can be used as an inert gas. This also applies to the steps described later.

[0073] At this point, regarding the ratio of oxygen to hydrogen in the first processed gas, the flow rates of the hydrogen-containing gas and the oxygen-containing gas are adjusted using MFCs 252a and 252b in such a way that the ratio of hydrogen to oxygen is the first ratio. Thus, by configuring the system to have separate hydrogen-containing gas supply systems and oxygen-containing gas supply systems, flow rate adjustment can be performed separately, thereby easily adjusting the mixing ratio of hydrogen-containing gas and oxygen-containing gas to control the hydrogen ratio in the processed gas.

[0074] It should be noted that in this specification, the "hydrogen-to-oxygen ratio" in the gas mainly refers to the ratio of the number of hydrogen atoms to the total number of oxygen atoms and hydrogen atoms in the gas.

[0075] Additionally, simultaneously with or after the start of the supply of the first processing gas, high-frequency (RF) power is applied to the resonant coil 212 from the high-frequency power supply 273. This excites annular induced plasmas, which appear as if viewed from above, at positions corresponding to the heights of the grounding and neutral points above and below the resonant coil 212 within the plasma generation space 201a. The excitation of the induced plasma activates the first processing gas containing hydrogen and oxygen, generating a reaction species containing an oxide. This reaction species includes at least one of excited-state O atoms (O*) acting as an oxide, ionized O atoms, excited-state OH radicals (OH*), and ions containing O and H. Furthermore, the reaction species includes at least one of excited-state H atoms (H*) and ionized H atoms as a reaction species containing H atoms. The reaction species containing H atoms can also be understood as part of an oxide species.

[0076] It should be noted that, as in this embodiment, by generating a reaction seed through plasma excitation of the processing gas supplied to the processing chamber 201, the reaction seed is directly supplied to the wafer 200. Therefore, compared with the case where the reaction seed generated outside the processing chamber 201 is supplied to the wafer 200, the generated reaction seed can be supplied to the wafer 200 more efficiently, thereby improving the efficiency of oxidation and modification of the surface of the wafer 200.

[0077] As a processing condition in this step, it can be exemplified as follows:

[0078] Processing temperature: room temperature to 300℃, preferably 100 to 200℃

[0079] Processing pressure: 1–1000 Pa, preferably 100–200 Pa

[0080] The hydrogen-to-oxygen ratio in the first treatment gas is 60–95%, preferably 70–95%.

[0081] The first processing gas supply flow rate is 0.1–10 slm, preferably 0.2–0.5 slm.

[0082] First processing gas supply time: 60–400 seconds, preferably 120–400 seconds; Inactive gas supply flow rate: 0–10 slm

[0083] RF power: 100–5000W, preferably 500–3500W

[0084] RF frequency: 800kHz~50MHz.

[0085] It should be noted that the numerical ranges expressed as "100~200℃" in this specification refer to the lower and upper limits, which are included within the range. Therefore, for example, "100~200℃" means "above 100℃ and below 200℃". The same applies to other numerical ranges. Furthermore, the processing temperature in this specification refers to the temperature of the wafer 200 or the temperature inside the processing chamber 201, and the processing pressure refers to the pressure inside the processing chamber 201. Additionally, a gas supply flow rate of 0 slm indicates that no gas is supplied. These same principles apply in the following descriptions.

[0086] Under the aforementioned processing conditions, the first processing gas is excited by plasma and then supplied to the wafer 200, thereby supplying a reaction seed containing an oxide seed to the surface of the wafer 200. Through the supplied reaction seed, the surface of the wafer 200 is oxidized, at least the surface is modified into a first oxide layer.

[0087] Here, as illustrated in the processing temperature example in this step, when using plasma-excited oxygen-containing gas to oxidize the substrate surface and form an oxide layer at lower processing temperatures, under conventional conditions, it is sometimes impossible to obtain the desired oxidation rate, and it is also difficult to form an oxide layer of the desired thickness. This is believed to be mainly because, at low temperatures, the oxide species generated by plasma excitation are difficult to diffuse in the modified substrate (e.g., a Si elemental substrate); at low temperatures, it is difficult to generate oxide species by plasma excitation (i.e., the amount of oxide species generated decreases); and so on.

[0088] To address this issue, measures such as increasing the processing temperature to promote the diffusion or formation of oxide seeds can be considered. However, increasing the processing temperature is generally not preferable for the thermal history (thermal budget) of the device structure formed on the wafer 200, and sometimes it is necessary to perform the modification process while maintaining the processing temperature at a lower level.

[0089] Therefore, in this step, by making the first ratio of hydrogen contained in the plasma-excited processing gas a predetermined ratio or higher, an increase in oxidation rate and / or an increase in oxide layer thickness is achieved at a lower processing temperature.

[0090] The following, more specifically, uses Figure 4 and Figure 5 Please provide an explanation. Figure 4 A graph showing the relationship between the ratio of hydrogen to oxygen in the processing gas and the thickness of the oxide layer formed by the modification treatment when the processing temperatures are 100°C, 300°C, 500°C, and 700°C, respectively. Figure 5 A graph showing the relationship between the processing temperature and the thickness of the oxide layer formed by the modification treatment is provided for cases where the ratio of hydrogen to oxygen in the processing gas is 0% (i.e., no hydrogen), 5%, 30%, 50%, 70%, and 95%. Regarding these modification treatment conditions, except for the processing temperature and the ratio of hydrogen in the processing gas, they are all within the same range as the conditions described in step a, and the object being modified is also the same (i.e., a Si elemental substrate).

[0091] like Figure 4 As shown, when modification is performed under relatively low processing temperatures such as 100°C and 300°C, in regions where the hydrogen ratio in the processing gas is between 60% and 95%, the thickness of the oxide layer formed by the modification tends to increase compared to regions with a relatively low hydrogen ratio. Furthermore, as... Figure 5 As shown, when modification is performed under conditions where the hydrogen ratio in the processing gas is 70% or 95%, the thickness of the oxide layer formed by the modification tends to increase in the region with a processing temperature below 300°C compared to the region with a higher temperature.

[0092] Thus, the reason why the oxidation rate or oxide layer thickness increases by increasing the ratio of hydrogen in the treatment gas under low temperature conditions is believed to be that the oxidation brought about by the oxidation species is promoted (assisted) by H and / or H-containing reactants in the treatment gas; under low temperature conditions, H and / or H-containing reactants that diffuse into the modified treatment object (substrate, etc.) are not easy to detach from the modified treatment object and are easy to remain; and so on.

[0093] Therefore, in this step, the following temperature is selected as the processing temperature: a temperature at which the oxidation rate (oxide layer formation rate) on the surface of wafer 200 increases, or the thickness of the formed oxide layer increases, when the ratio of hydrogen in the processing gas is increased in this step. By selecting such a processing temperature, even under low-temperature conditions, the oxidation rate or the thickness of the oxide layer can be maintained or increased by increasing the ratio of hydrogen in the first processing gas.

[0094] Furthermore, in this step, regarding the first ratio of hydrogen contained in the first processing gas, the following ratio is selected: a ratio that decreases the oxidation rate on the surface of wafer 200 as the processing temperature increases in this step; or a ratio that decreases the thickness of the formed oxide layer. In other words, in this step, the first ratio is selected such that a hydrogen ratio increases the oxidation rate on the surface of wafer 200 as the processing temperature decreases in this step. By selecting such a hydrogen ratio, the oxidation rate or the thickness of the oxide layer can be maintained or increased even under low-temperature conditions.

[0095] More specifically, in this step, the processing temperature is set to between room temperature and 300°C, preferably between 100°C and 200°C, and the hydrogen content in the first processing gas is set to between 60% and 95%, preferably between 70% and 95%.

[0096] By keeping the processing temperature below 300°C, the oxidation rate and oxide layer thickness can be maintained even when using a processing gas with a high hydrogen ratio in this step. When the processing temperature exceeds 300°C, it becomes difficult to maintain the oxidation rate or oxide layer thickness when using a processing gas with a high hydrogen ratio, and the thermal history can significantly affect the device structure on the wafer 200. Furthermore, by keeping the processing temperature below 200°C, this step can be performed using a processing gas with a high hydrogen ratio, thereby increasing the oxidation rate and oxide layer thickness. It should be noted that by keeping the processing temperature above room temperature, cooling of the wafer 200 is unnecessary, and by keeping the processing temperature above 100°C, temperature stability of the wafer 200 is easily achieved.

[0097] Furthermore, by maintaining the hydrogen content in the first processing gas at 60% to 95%, the oxidation rate or oxide layer thickness can be maintained or increased even at low temperatures, such as below 300°C. When the hydrogen content is less than 60%, it becomes difficult to maintain the oxidation rate or oxide layer thickness at low temperatures. When the hydrogen content exceeds 95%, the amount of oxide seeds generated by plasma excitation decreases significantly, making it difficult to maintain a practical oxidation rate or oxide layer thickness.

[0098] It should be noted that the thickness of the oxide layer formed on the surface of wafer 200 in this step is preferably 4 nm or more, more preferably 5 nm or more. By forming an oxide layer with a thickness of 4 nm or more, insulation can be ensured even when this oxide layer is used as an insulating layer. Furthermore, for example... Figure 5 As shown, in low-temperature regions where the processing temperature is, for example, below 200°C, and the hydrogen ratio in the processing gas is less than 70%, it is difficult to form an oxide layer with a thickness of 4 nm or more. Therefore, in order to form an oxide layer with a thickness of 4 nm or more in low-temperature regions, it is preferable to perform modification treatment using the processing conditions in this step.

[0099] Here, it is believed that the hydrogen contained in the processing gas remains in the first oxide layer formed on the surface of the wafer 200 during this step, thus reducing the properties of the first oxide layer, such as its processability (resistance to wet etching, resistance to dry etching, etc.) and electrical properties. Therefore, in this embodiment, the first oxide layer is modified by further performing step b (described later) after this step (step a) to reduce the hydrogen concentration therein, thereby improving its properties.

[0100] After the above modification treatment is completed, valves 253a and 253b are closed to stop the supply of hydrogen-containing gas and oxygen-containing gas to the treatment chamber 201, and the supply of RF power to the resonant coil 212 is also stopped. Then, a vacuum is vented from the treatment chamber 201 to remove any remaining gases. At this time, valve 253c is opened to supply inactive gas to the treatment chamber 201. The inactive gas acts as a purge gas, thereby purging the treatment chamber 201.

[0101] It should be noted that in this embodiment, the above-mentioned purging process is performed between the modification treatment in step a and step b. However, this purging process may be omitted, and instead, after the modification treatment in step a is completed, RF power is continued to be applied to the resonant coil 212, and step b is started continuously. In this case, the supply flow rate and flow ratio (i.e., the ratio of hydrogen in the treated gas) of hydrogen-containing gas and oxygen-containing gas into the treatment chamber 201 can be varied in a stepwise manner. Alternatively, they can be varied gradually over a specified time.

[0102] [Step b: Second oxide layer formation process]

[0103] In step b, the following steps are performed: step b-1, supplying oxygen-containing gas and hydrogen-containing gas into the processing chamber 201; and step b-2, plasma-exciting the gas containing oxygen-containing gas and hydrogen-containing gas supplied to the processing chamber 201, and supplying the reaction seeds generated by plasma excitation to the wafer 200, thereby modifying the first oxide layer into a second oxide layer.

[0104] Specifically, valve 253a is opened to allow hydrogen-containing gas to flow into gas supply pipe 232a, and valve 253b is opened to allow oxygen-containing gas to flow into gas supply pipe 232b. The flow rates of the hydrogen-containing gas and oxygen-containing gas are regulated using MFCs 252a and 252b, respectively, and supplied to the processing chamber 201 via buffer chamber 237, and exhausted from exhaust port 235. At this time, a mixture of hydrogen-containing gas and oxygen-containing gas (the second processing gas supply) is supplied to the processing chamber 201 as the second processing gas containing hydrogen and oxygen. It should be noted that, similar to step a, an inactive gas can also be supplied to the processing chamber 201 simultaneously.

[0105] At this point, regarding the ratio of oxygen to hydrogen in the second processed gas, the flow rates of hydrogen-containing gas and oxygen-containing gas are regulated using MFC 252a and 252b in a manner that makes the ratio of hydrogen to oxygen a second ratio that is less than the first ratio.

[0106] Additionally, RF power is applied to the resonant coil 212 from the high-frequency power supply 273 simultaneously with or after the start of the supply of the second processing gas. As a result, similar to step a, induced plasma is excited within the plasma generation space 201a. Through the excitation of the induced plasma, the second processing gas containing hydrogen and oxygen is activated, generating a reaction species containing oxides, similar to step a. However, since this step involves plasma excitation of the second processing gas with a hydrogen ratio lower than that of the first processing gas, it is assumed that the hydrogen (atoms) ratio in the generated reaction species is lower than that in the reaction species generated in step a.

[0107] As a processing condition in this step, it can be exemplified as follows:

[0108] The hydrogen-to-oxygen ratio in the second treatment gas is 0–20%, preferably 5–20%.

[0109] The second processing gas supply flow rate is 0.1–10 slm, preferably 0.2–0.5 slm.

[0110] The second processing gas supply time is 60 to 400 seconds, preferably 120 to 400 seconds.

[0111] The processing temperature is substantially the same as or lower than that in step a. Specifically, considering factors such as minimizing the time required for temperature changes between steps and promoting the modification of the first oxide layer, it is preferable that the processing temperature is substantially the same as that in step a, compared to a processing temperature lower than that in step a. Alternatively, the processing temperature can be higher than that in step a, but in this case, considering the impact of the thermal process on the device structure on the wafer 200, it should be selected from a range below the permissible temperature.

[0112] Alternatively, the supply time can be the same as the supply time of the first processing gas in step a. However, it is preferable to adjust the supply time of the second processing gas according to the allowable concentration of hydrogen (atoms) remaining in the second oxide layer. For example, if the allowable concentration of hydrogen is high, the supply time is shortened; if the allowable concentration of hydrogen is low, the supply time is extended, thereby improving productivity.

[0113] Other processing conditions are the same as those in step a when nitrogen-containing gas is supplied.

[0114] By supplying the second processing gas to the wafer 200 under the above processing conditions using plasma to excite it, a reaction seed containing oxide seeds is supplied to the first oxide layer on the wafer 200. Through the supplied reaction seed, the first oxide layer is modified into a second oxide layer.

[0115] Specifically, in this step, a reaction species with a lower hydrogen content compared to the reaction species generated in step a is supplied to the first oxide layer. This suppresses hydrogen entry into the first oxide layer while simultaneously causing hydrogen (atoms) entering the first oxide layer to detach from the layer via oxide species, thus modifying the first oxide layer into one with a lower hydrogen concentration. The modified second oxide layer exhibits improved oxide layer properties compared to the first oxide layer, including improved processing resistance (wet etching resistance, dry etching resistance, etc.) and electrical properties. For example, compared to the first oxide layer, the second oxide layer has a higher wet etching rate (WER) compared to the first oxide layer. The rate decreases by 1 / minute. The evaluation of WER utilizes, for example, the etching rate when etching is performed using a 1% diluted aqueous solution of hydrogen fluoride (DHF solution).

[0116] In this step, regarding the second ratio of hydrogen contained in the second processing gas, it is preferable to select a hydrogen ratio in which the oxidation rate of the wafer 200 surface increases with the increase of the processing temperature in the modification process of step a. By selecting such a hydrogen ratio, the hydrogen contained in the first oxide layer can be efficiently removed while maintaining low temperature conditions.

[0117] More specifically, in this step, the hydrogen content in the second processing gas is set to 0% to 20%, preferably 5% to 20%. By setting the hydrogen content in the second processing gas to 0% to 20%, hydrogen contained in the first oxide layer can be removed while maintaining low-temperature conditions. When the hydrogen content in the second processing gas exceeds 20%, it becomes difficult to remove hydrogen contained in the first oxide layer. Furthermore, by setting the hydrogen content in the second processing gas to 5% or more, hydrogen contained in the first oxide layer can be removed efficiently while maintaining low-temperature conditions. When it is less than 5%, the generation of OH radicals decreases, which reduces the efficiency of hydrogen removal from the first oxide layer.

[0118] After the above modification treatment is completed, valves 253a and 253b are closed to stop the supply of hydrogen-containing gas and oxygen-containing gas to the treatment chamber 201, and to stop the supply of RF power to the resonant coil 212.

[0119] (After purging and atmospheric pressure recovery)

[0120] After step b is completed, a vacuum is vented from the processing chamber 201 to remove any remaining gases or other substances. Then, using the same processing steps and conditions as described above, any remaining gaseous substances or other substances in the processing chamber 201 are removed (post-purging). The atmosphere in the processing chamber 201 is then replaced with the purging gas, and the pressure inside the processing chamber 201 is restored to atmospheric pressure (atmospheric pressure restoration).

[0121] (Chip removal)

[0122] 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 the processed wafer 200 is moved out of the processing chamber 201 using a transport mechanism (not shown). This concludes the substrate processing steps involved in this method.

[0123] (3) Variations

[0124] The substrate processing sequence of this method 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.

[0125] (Variation Example 1)

[0126] In this modified example, in step b, the hydrogen content of the second processed gas is set to 0%, i.e., it contains no hydrogen. Specifically, in step b, hydrogen-containing gas is not supplied from the hydrogen-containing gas supply system; only oxygen-containing gas is supplied from the oxygen-containing gas supply system. Furthermore, in this case, hydrogen-free gases such as O2 or O3 are used as the oxygen-containing gas.

[0127] In this modified example, the same effect as described above can also be obtained. Furthermore, according to this modified example, the second processing gas in step b is made free of hydrogen; therefore, no new hydrogen enters the first oxide layer in step b, potentially promoting the removal of hydrogen from the first oxide layer.

[0128] (Variation Example 2)

[0129] In the above embodiment, the following example will be described: In step a, a mixture of gases supplied from the hydrogen-containing gas supply system and the oxygen-containing gas supply system is supplied to the processing chamber 201 as a first processing gas; similarly, in step b, a mixture of gases supplied from the hydrogen-containing gas supply system and the oxygen-containing gas supply system is supplied to the processing chamber 201 as a second processing gas. In contrast, the substrate processing apparatus according to this modified example includes: a first processing gas supply system that supplies a first processing gas containing a hydrogen ratio of a first ratio; and a second processing gas supply system that supplies a second processing gas containing a hydrogen ratio of a second ratio.

[0130] More specifically, for example, it can be like Figure 6 The configuration shown includes: a first processing gas supply system having a first processing gas supply source 250a' instead of the hydrogen-containing gas supply source 250a in the above embodiment; and a second processing gas supply system having a second processing gas supply source 250b' instead of the oxygen-containing gas supply source 250b in the above embodiment. Furthermore, control is performed using a controller 121 such that: in step a, a first processing gas is supplied from the first processing gas supply system into the processing chamber 201; and in step b, a second processing gas is supplied from the second processing gas supply system into the processing chamber 201.

[0131] Alternatively, as in Modification 1, the second processing gas supplied from the second processing gas supply system may be specifically configured as an oxygen-containing gas that does not contain hydrogen.

[0132] <Other ways of publishing this text>

[0133] The foregoing has specifically described the manner of this disclosure. However, this disclosure is not limited to the above manner, and various modifications can be made without departing from the spirit of the invention.

[0134] The above description focuses on an example where a Si-based substrate is used as the target for modification. However, this disclosure is not limited to this. The target for modification may, for example, be a Si-containing substance (Si compound) such as silicon nitride (SiN), silicon oxynitride (SiON), silicon oxycarbonitride (SiOCN), silicon germanium (SiGe), or silicon carbide (SiC). Furthermore, the target for oxidation treatment may, for example, be a metal containing aluminum (Al), tungsten (W), molybdenum (Mo), titanium (Ti), hafnium (Hf), or zirconium (Zr), or a compound thereof. However, substances other than their oxides are preferred.

[0135] The above description illustrates an example of performing steps a and b consecutively within a single processing chamber (i.e., processing chamber 201), but this disclosure is not limited to this. For example, after performing step a on the substrate, the substrate may be moved from the processing chamber where it was processed to a transport chamber that is not open to the atmosphere. Subsequently, the substrate may be moved to another processing chamber for step b.

[0136] The above-described method, for example, describes a substrate processing example using a monolithic substrate processing apparatus that processes one or more substrates at a time. This disclosure is not limited to the above-described method and can also be suitably applied to cases using an intermittent substrate processing apparatus that processes multiple substrates at a time.

[0137] When using the above-described substrate processing apparatus, each processing step and processing condition can be performed using the same processing steps and processing conditions as those in the above-described method and modified examples, and the same effect as in the above-described method and modified examples can be obtained.

Claims

1. A substrate processing method comprising the following steps: (a) A process of modifying the surface of a substrate into a first oxide layer by supplying a reaction seed to the substrate, the reaction seed being generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and (b) A process of modifying the first oxide layer into a second oxide layer by supplying the substrate with the following reaction seed, wherein the reaction seed is generated by plasma excitation of a second processing gas containing oxygen and hydrogen, wherein the hydrogen-to-oxygen ratio is a second ratio less than the first ratio. in, The first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

2. The substrate processing method as described in claim 1, wherein, The temperature of the substrates in (a) and (b) is the same specified temperature.

3. The substrate processing method as described in claim 2, wherein, The specified temperature is selected as the temperature at which, in (a), the greater the ratio of hydrogen to oxygen in the first processing gas, the greater the oxidation rate of the substrate surface.

4. The substrate processing method as described in claim 2, wherein, The specified temperature is below 300℃.

5. The substrate processing method as described in claim 1, wherein, (a) The first processing gas excited by plasma does not contain inactive gases.

6. The substrate processing method as described in claim 1, wherein, The first ratio is between 60% and 95%.

7. The substrate processing method as described in claim 1, wherein, The second ratio is below 20%.

8. The substrate processing method as described in claim 7, wherein, The second ratio is 5% or higher.

9. The substrate processing method as described in claim 1, wherein, The surface of the substrate modified into the first oxide layer in (a) is composed of a silicon-containing substrate.

10. The substrate processing method as described in claim 9, wherein, The silicon-containing substrate is composed of elemental silicon.

11. The substrate processing method as described in claim 1, wherein, The thickness of the first oxide layer is 4 nm or more.

12. The substrate processing method as described in claim 1, wherein, The hydrogen concentration in the second oxide layer is lower than that in the first oxide layer.

13. The substrate processing method as described in claim 1, wherein, In (a), the first processing gas supplied to the processing chamber containing the substrate is subjected to plasma excitation. In (b), the second processing gas supplied to the processing chamber is subjected to plasma excitation.

14. The substrate processing method as described in claim 1, wherein, The first processing gas is a mixture of oxygen and hydrogen.

15. The substrate processing method as described in claim 2, wherein, The specified temperature is between 100℃ and 200℃.

16. A substrate processing method, comprising: (a) A process of modifying the surface of a substrate into a first oxide layer by supplying a reaction seed to the substrate, the reaction seed being generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and (b) A step of modifying the first oxide layer into a second oxide layer by supplying a reaction seed to the substrate, wherein the reaction seed is generated by plasma excitation of a second processing gas containing oxygen but not hydrogen. in, The first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

17. A method for manufacturing a semiconductor device, comprising: (a) A process of modifying the surface of a substrate into a first oxide layer by supplying a reaction seed to the substrate, the reaction seed being generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and (b) A process of modifying the first oxide layer into a second oxide layer by supplying the substrate with the following reaction seed, wherein the reaction seed is generated by plasma excitation of a second processing gas containing oxygen and hydrogen, wherein the hydrogen-to-oxygen ratio is less than the first ratio. in, The first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

18. A method for manufacturing a semiconductor device, comprising: (a) A process of modifying the surface of a substrate into a first oxide layer by supplying a reaction seed to the substrate, the reaction seed being generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and (b) A step of modifying the first oxide layer into a second oxide layer by supplying a reaction seed to the substrate, wherein the reaction seed is generated by plasma excitation of a second processing gas containing oxygen but not hydrogen. in, The first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

19. A substrate processing apparatus, comprising: The plasma generation space where plasma is generated; An oxygen-containing gas supply system that supplies oxygen-containing gas into the plasma generation space; A hydrogen gas supply system that supplies hydrogen gas into the plasma generation space; The excitation unit excites the gas supplied to the plasma generation space to generate plasma; and The control unit is configured to control the oxygen-containing gas supply system, the hydrogen-containing gas supply system, and the excitation unit to perform the following processes: (a-1) A process of supplying a first processing gas, which is a mixture of the oxygen-containing gas and the hydrogen-containing gas, with a hydrogen-to-oxygen ratio of a first ratio, into the plasma generation space; (a-2) A process of modifying the surface of the substrate into a first oxide layer by supplying a reaction seed generated by plasma excitation of the first processing gas into the substrate; (b-1) A process of supplying a second processing gas, which is a mixture of the oxygen-containing gas and the hydrogen-containing gas, with a hydrogen-to-oxygen ratio of a second ratio less than the first ratio, into the plasma generation space; and (b-2) A process of modifying the first oxide layer into a second oxide layer by supplying a reaction seed generated by plasma excitation of the second processing gas into the substrate. in, The first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

20. A substrate processing apparatus, comprising: The plasma generation space where plasma is generated; An oxygen-containing gas supply system that supplies oxygen-containing gas (without hydrogen) into the plasma generation space; A hydrogen gas supply system that supplies hydrogen gas into the plasma generation space; The excitation unit excites the gas supplied to the plasma generation space to generate plasma; and The control unit is configured to control the oxygen-containing gas supply system, the hydrogen-containing gas supply system, and the excitation unit to perform the following processes: (a-1) A process of supplying a first processing gas, which is a mixture of the oxygen-containing gas and the hydrogen-containing gas, with a hydrogen-to-oxygen ratio of a first ratio, into the plasma generation space; (a-2) A process of modifying the surface of the substrate into a first oxide layer by supplying a reaction seed generated by plasma excitation of the first processing gas into the substrate; (b-1) A process of supplying a second processing gas, which contains the oxygen-containing gas but does not contain the hydrogen-containing gas, into the plasma generation space; and (b-2) A process of modifying the first oxide layer into a second oxide layer by supplying a reaction seed generated by plasma excitation of the second processing gas into the substrate. in, The first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

21. A computer-readable recording medium having a program recorded thereon that enables a substrate processing apparatus to perform the following steps using a computer, the steps including: (a) A step of modifying the surface of a substrate into a first oxide layer by supplying a reaction seed to a substrate housed in a processing chamber of a substrate processing apparatus, wherein the reaction seed is generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and (b) The step of modifying the first oxide layer into a second oxide layer by supplying the substrate with the following reaction seed, wherein the reaction seed is generated by plasma excitation of a second processing gas containing oxygen and hydrogen, wherein the hydrogen-to-oxygen ratio is less than the first ratio. Wherein, the first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

22. A computer-readable recording medium having a program recorded thereon that enables a substrate processing apparatus to perform the following steps using a computer, the steps including: (a) A step of modifying the surface of a substrate into a first oxide layer by supplying a reaction seed to a substrate housed in a processing chamber of a substrate processing apparatus, wherein the reaction seed is generated by plasma excitation of a first processing gas containing oxygen and hydrogen in a hydrogen-to-oxygen ratio of a first ratio; and (b) The step of modifying the first oxide layer into a second oxide layer by supplying a reaction seed to the substrate, wherein the reaction seed is generated by plasma excitation of a second processing gas containing oxygen and not hydrogen. Wherein, the first ratio is selected as the ratio of hydrogen to oxygen in (a) such that the lower the temperature of the substrate, the greater the oxidation rate of the substrate surface.

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