Substrate processing method and plasma processing apparatus

Abstract

The present invention provides a substrate processing method and a plasma processing apparatus for forming a nitride film. [Solution] A substrate processing method comprising the steps of: generating ammonia plasma; detecting the emission spectrum of the ammonia plasma; adjusting the plasma generation conditions based on the emission intensity of the emission wavelength derived from NH radicals in the emission spectrum; generating ammonia plasma under the adjusted plasma generation conditions and performing a nitriding treatment on the substrate; supplying a raw material gas to the substrate and performing an adsorption treatment to adsorb the raw material gas onto the substrate; and repeating the cycle, with the nitriding treatment and the adsorption treatment forming one cycle.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a method for forming a metal nitride film.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On one aspect, the present disclosure provides a substrate processing method and a plasma processing apparatus for forming a nitride film.

Means for Solving the Problems

[0005] In order to solve the above problems, according to one aspect, there is provided a substrate processing method including: a step of generating ammonia plasma; a step of detecting an emission spectrum of the ammonia plasma; a step of adjusting plasma generation conditions based on the emission intensity of an emission wavelength derived from NH radicals in the emission spectrum; a step of generating ammonia plasma under the adjusted plasma generation conditions and performing nitriding treatment on a substrate; a step of supplying a raw material gas to the substrate and performing an adsorption treatment of adsorbing the raw material gas on the substrate; and a step of repeating the cycle with the nitriding treatment and the adsorption treatment as one cycle. <​​​​​​​​​

[0007] [Figure 1] An example of a schematic diagram showing an example of the configuration of a plasma processing apparatus. [Figure 2] An example of a schematic diagram showing the configuration of a plasma processing apparatus with the processing vessel horizontally cut. [Figure 3] Another example of a schematic diagram showing an example of the configuration of a plasma processing apparatus. [Figure 4] A flowchart illustrating an example of substrate processing. [Figure 5] A flowchart illustrating an example of a process for adjusting plasma generation conditions. [Figure 6] An example of the emission spectrum of ammonia plasma. [Figure 7] An example of a potential energy curve for an NH radical. [Figure 8] A model diagram illustrating the nitridation reaction of NH radicals onto chemically adsorbed DCS. [Modes for carrying out the invention]

[0008] The following describes embodiments for implementing this disclosure with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0009] [Example of a plasma processing device] An example of the plasma processing apparatus 100 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is an example of a schematic diagram showing an example of the configuration of the plasma processing apparatus 100. Figure 2 is an example of a schematic diagram showing an example of the configuration of the plasma processing apparatus 100 when the processing vessel 1 is cut horizontally. Here, the plasma processing apparatus 100 is a batch-type plasma processing apparatus having a remote plasma source, and is a film deposition apparatus that deposits a silicon nitride film (SiN) on a substrate W using the plasma ALD (Plasma-enhanced atomic layer deposition) method.

[0010] The plasma processing apparatus 100 has a cylindrical processing vessel 1 with a ceiling that is open at the lower end. The entire processing vessel 1 is made of, for example, quartz. A ceiling plate 2 made of quartz is provided near the upper end of the processing vessel 1, and the area below the ceiling plate 2 is sealed. A cylindrical metal manifold 3 is connected to the opening at the lower end of the processing vessel 1 via a sealing member 4 such as an O-ring.

[0011] The manifold 3 supports the lower end of the processing container 1, and a wafer boat (substrate support section) 5, which supports a large number of semiconductor wafers (e.g., 25 to 150 wafers, hereinafter referred to as "substrates W") in multiple stages, is inserted into the processing container 1 from below the manifold 3. In this way, a large number of substrates W are housed in the processing container 1 in a substantially horizontal manner with spacing along the vertical direction. The wafer boat 5 is made of, for example, quartz. The wafer boat 5 has three rods 6 (two are shown in Figure 1), and the large number of substrates W are supported by grooves (not shown) formed in the rods 6.

[0012] The wafer boat 5 is placed on the table 8 via a heat-insulating tube 7 made of quartz. The table 8 is supported on a rotating shaft 10 that passes through a metal (stainless steel) cover 9 that opens and closes the opening at the lower end of the manifold 3.

[0013] A magnetic fluid seal 11 is provided at the penetration portion of the rotating shaft 10, which hermetically seals the rotating shaft 10 and supports it so that it can rotate. A sealing member 12 is provided between the periphery of the lid 9 and the lower end of the manifold 3 to maintain airtightness inside the processing container 1.

[0014] The rotating shaft 10 is attached to the tip of an arm 13 supported by a lifting mechanism (not shown), such as a boat elevator, and the wafer boat 5 and the lid 9 move up and down together and are inserted into and removed from the processing container 1. Alternatively, a table 8 may be fixed to the lid 9 side, allowing the substrate W to be processed without rotating the wafer boat 5.

[0015] In addition, the plasma processing apparatus 100 includes a gas supply unit (processing gas supply unit) 20 that supplies predetermined gases such as a processing gas and a purge gas into the processing chamber 1.

[0016] The gas supply unit 20 includes gas supply pipes 21, 22, and 23. The gas supply pipe 21 is formed of, for example, quartz, penetrates the side wall of the manifold 3 inward, bends upward, and extends vertically. A plurality of gas holes 21g are formed at predetermined intervals over the vertical length corresponding to the wafer support range of the wafer boat 5 in the vertical portion of the gas supply pipe 21. Each gas hole 21g discharges gas in the horizontal direction. The gas supply pipe 22 is formed of, for example, quartz, penetrates the side wall of the manifold 3 inward, bends upward, and extends vertically. A plurality of gas holes 22g are formed at predetermined intervals over the vertical length corresponding to the wafer support range of the wafer boat 5 in the vertical portion of the gas supply pipe 22. Each gas hole 22g discharges gas in the horizontal direction. The gas supply pipe 23 is composed of, for example, a short quartz pipe provided through the side wall of the manifold 3.

[0017] The vertical portion (the vertical portion where the gas holes 21g are formed) of the gas supply pipe 21 is provided inside the processing chamber 1. A processing gas is supplied to the gas supply pipe 21 from a gas supply source 21a via a gas pipe. A flow controller 21b and an on-off valve 21c are provided in the gas pipe. Thus, the processing gas from the gas supply source 21a is supplied into the processing chamber 1 via the gas pipe and the gas supply pipe 21. Note that, for example, raw material gases (precursor gases) such as dichlorosilane (SiH2Cl2) gas, monochlorosilane (SiHCl3) gas, and trichlorosilane (SiH3Cl) gas can be used as the processing gas supplied from the gas supply source 21a. In the following description, dichlorosilane (SiH2Cl2) gas (hereinafter also referred to as DCS) is used as the raw material gas (precursor gas).

[0018] Thus, the raw material gas supply unit includes a gas supply pipe 21, a gas supply source 21a, a flow controller 21b, a flow controller 21b, and an on / off valve 21c. The raw material gas supply unit supplies raw material gas to the processing space within the processing container 1.

[0019] The gas supply pipe 22 has a vertical portion (the vertical portion where the gas holes 22g are formed) located in the plasma generation space, which will be described later. Process gas is supplied to the gas supply pipe 22 from the gas supply source 22a via gas piping. The gas piping is equipped with a flow controller 22b and an on-off valve 22c. As a result, the process gas from the gas supply source 22a is supplied to the plasma generation space via gas piping and the gas supply pipe 21, where it is plasma-generated and supplied into the processing container 1. The process gas supplied from the gas supply source 22a can be, for example, a nitriding gas such as ammonia (NH3) gas. In the following description, ammonia (NH3) gas will be used as the nitriding gas.

[0020] Purge gas is supplied to the gas supply pipe 23 from a purge gas supply source (not shown) via gas piping. The gas piping (not shown) is equipped with a flow controller (not shown) and an on / off valve (not shown). As a result, the purge gas from the purge gas supply source is supplied into the processing container 1 via the gas piping and gas supply pipe 23. As the purge gas, an inert gas such as argon (Ar) or nitrogen (N2) can be used. Although the case in which the purge gas is supplied from the purge gas supply source to the processing container 1 via the gas piping and gas supply pipe 23 has been described, the system is not limited to this, and the purge gas may also be supplied from the gas supply pipe 21.

[0021] A plasma generation mechanism 30 is formed in a portion of the side wall of the processing container 1. The plasma generation mechanism 30 converts the processing gas from the gas supply source 22a into plasma.

[0022] The plasma generation mechanism 30 comprises a plasma compartment wall 32, a pair of plasma electrodes 33 (one is shown in Figure 1), a power supply line 34, and a high-frequency power supply 35. The plasma generation mechanism (remote plasma section) 30 generates a nitride gas plasma (ammonia plasma) in the plasma generation space and supplies radicals to the processing space in the processing container 1.

[0023] The plasma compartment wall 32 is hermetically welded to the outer wall of the processing vessel 1. The plasma compartment wall 32 is made of, for example, quartz. The plasma compartment wall 32 has a concave cross-section and covers the opening 31 formed in the side wall of the processing vessel 1. The opening 31 is elongated in the vertical direction so as to cover all the substrates W supported by the wafer boat 5 in the vertical direction. A gas supply pipe 22 for discharging processing gas is located in the inner space defined by the plasma compartment wall 32 and communicating with the inside of the processing vessel 1, i.e., the plasma generation space. The gas supply pipe 21 for discharging processing gas is located near the substrates W along the inner wall of the processing vessel 1 outside the plasma generation space.

[0024] A pair of plasma electrodes 33 (one is shown in Figure 1) each have an elongated shape and are arranged facing each other vertically on the outer surfaces of the walls on both sides of the plasma compartment wall 32. Each plasma electrode 33 is held by a holding part (not shown) provided, for example, on the side of the plasma compartment wall 32. A power supply line 34 is connected to the lower end of each plasma electrode 33.

[0025] The power supply line 34 electrically connects each plasma electrode 33 to the high-frequency power supply 35. In the illustrated example, one end of the power supply line 34 is connected to the lower end of each plasma electrode 33, and the other end is connected to the high-frequency power supply 35.

[0026] The high-frequency power supply 35 is connected to the lower end of each plasma electrode 33 via a power supply line 34 and supplies high-frequency power of, for example, 13.56 MHz to the pair of plasma electrodes 33. This applies high-frequency power to the plasma generation space defined by the plasma partition wall 32. The processing gas discharged from the gas supply pipe 21 is plasma-generated in the plasma generation space to which high-frequency power is applied, and supplied to the inside of the processing container 1 through the opening 31. That is, the active species (radicals, etc.) of the nitride gas generated in the plasma generation space are supplied to the processing container 1 (processing space) through the opening 31. Specifically, NH3, NH2, NH, N, H, etc. are supplied to the processing container 1. In addition, ions generated in the plasma generation space are drawn towards the plasma electrodes 33, thereby suppressing the supply of ions to the processing space.

[0027] An exhaust port (exhaust section) 40 for vacuuming the inside of the processing container 1 is provided on the side wall portion of the processing container 1 facing the opening 31. The exhaust port 40 is formed to be long and narrow vertically, corresponding to the wafer boat 5. An exhaust port cover member 41, which is formed in a U-shape in cross-section, is attached to the portion of the processing container 1 corresponding to the exhaust port 40. The exhaust port cover member 41 extends upward along the side wall of the processing container 1. An exhaust pipe 42 for exhausting the processing container 1 through the exhaust port 40 is connected to the lower part of the exhaust port cover member 41. An exhaust device 44, which includes a pressure control valve 43 for controlling the pressure inside the processing container 1 and a vacuum pump, is connected to the exhaust pipe 42, and the inside of the processing container 1 is exhausted through the exhaust pipe 42 by the exhaust device 44.

[0028] A cylindrical heating mechanism 50 is provided around the processing container 1. The heating mechanism 50 heats the processing container 1 and the substrate W inside it. The heating mechanism 50 controls the temperature of the processing container 1 to a desired temperature (for example, a temperature of 600°C or lower). As a result, the substrate W inside the processing container 1 is heated by radiant heat from the walls of the processing container 1.

[0029] The plasma processing apparatus 100 also has a plasma emission detection unit 200 that detects the emission of plasma generated in the plasma generation space within the plasma compartment wall 32. The plasma emission detection unit 200 includes a light receiving unit 210, an optical fiber 220, and a plasma monitor 230. Here, the plasma compartment wall 32 is formed of, for example, quartz, and the plasma light generated within the plasma compartment wall 32 passes through the plasma compartment wall 32. The light receiving unit 210 is provided on the outside of the plasma compartment wall 32, penetrating the heating mechanism 50. The plasma light generated within the plasma compartment wall 32 passes through the plasma compartment wall 32 and is incident on the light receiving unit 210. The plasma light incident on the light receiving unit 210 is input to the plasma monitor 230 via the optical fiber 220. The plasma monitor 230 is a spectrometer. The plasma monitor 230 acquires the emission spectrum in a predetermined wavelength range (in the example of Figure 6 described later, the wavelength range is 320 nm to 340 nm). The plasma monitor 230 then spectrally analyzes the plasma for each wavelength (resolution in the wavelength domain) and detects the emission intensity for each wavelength (resolution in the wavelength domain).

[0030] The plasma processing apparatus 100 also has a control unit 60. The control unit 60 controls the operation of each part of the plasma processing apparatus 100, for example, the supply and cessation of each gas by opening and closing the on / off valves 21c and 22c, the control of the gas flow rate by the flow controllers 21b and 22b, and the exhaust control (pressure control of the plasma generation space) by the exhaust device 44. The control unit 60 also controls the on / off of high-frequency power by the high-frequency power supply 35, for example, and the temperature of the processing container 1 and the substrate W inside it by the heating mechanism 50.

[0031] Furthermore, the control unit 60 adjusts the plasma generation conditions based on the emission intensity of a predetermined wavelength (a wavelength of 336.0 nm derived from NH radicals, described later) detected by the plasma monitor 230. The plasma generation conditions include pressure control of the plasma generation space and / or power control of the high-frequency power.

[0032] The control unit 60 may be, for example, a computer. Furthermore, the computer program that controls the operation of each part of the plasma processing apparatus 100 is stored in a storage medium. The storage medium may be, for example, a flexible disk, compact disk, hard disk, flash memory, DVD, etc.

[0033] [Another example of a plasma processing device] In Figure 1, the plasma processing apparatus 100 is described using a batch-type plasma processing apparatus as an example, but it is not limited to this. A single-wafer plasma processing apparatus may also be used. Figure 3 is another example of a schematic diagram showing the configuration of the plasma processing apparatus 100A. Here, the plasma processing apparatus 100A is a single-wafer plasma processing apparatus having a remote plasma source, and is a film deposition apparatus that deposits a silicon nitride (SiN) film on a substrate W using the plasma ALD method.

[0034] The plasma processing apparatus 100A comprises a processing vessel 310, a susceptor 320, a gas shower head 330, an insulating side wall 340, a high-frequency electrode 350, a high-frequency power supply 360, an exhaust device 370, and a control unit 380.

[0035] The processing container 310 is a roughly cylindrical metal container that is grounded. The processing container 310 has a processing space S1 inside it.

[0036] The susceptor (substrate support) 320 is provided within the processing space S1 and supports the substrate W in a substantially horizontal position. The susceptor 320 also has a temperature control mechanism (not shown), such as a heater, for adjusting the temperature of the susceptor 320 and the substrate W. The temperature control mechanism controls the temperature of the susceptor 320 (the temperature of the substrate W placed on the susceptor 320) to a desired temperature (for example, a temperature of 600°C or less). The susceptor 320 is also grounded.

[0037] The gas shower head 330 is positioned above the susceptor 320 and separates the processing space S1 from the plasma generation space S2. The gas shower head 330 also has a gas discharge section 331 and a communication hole 332.

[0038] The gas supply passage 335 is connected to a raw material gas supply source (not shown) and supplies raw material gas (e.g., DCS gas) to the gas discharge section 331. The gas discharge section 331 discharges the raw material gas (e.g., DCS gas) supplied from the gas supply passage 335 into the processing space S1.

[0039] Thus, the raw material gas supply unit includes a gas shower head 330, a gas supply channel 335, and a raw material gas supply source (not shown). The raw material gas supply unit supplies raw material gas to the processing space S1 within the processing container 310.

[0040] A plasma generation space S2 is formed by the gas shower head 330, the insulating side wall 340, and the high-frequency electrode 350. A communication hole 332 in the gas shower head 330 connects the processing space S1 and the plasma generation space S2. The insulating side wall 340 is positioned between the gas shower head 330 and the high-frequency electrode 350, and insulates the gas shower head 330 from the high-frequency electrode 350. The high-frequency electrode 350 is positioned above the gas shower head 330 and opposite the gas shower head 330.

[0041] The high-frequency electrode 350 is connected to the high-frequency power supply 360. The high-frequency power supply 360 supplies high-frequency power to the high-frequency electrode 350 for plasma generation. The gas shower head 330 is also grounded. As a result, high-frequency power is applied to the plasma generation space S2 between the high-frequency electrode 350 and the gas shower head 330.

[0042] The gas supply channel 336 is connected to a nitride gas supply source (not shown) and supplies nitride gas (e.g., NH3 gas) to the plasma generation space S2. The nitride gas (e.g., NH3 gas) supplied from the gas supply channel 336 to the plasma generation space S2 is plasma-generated within the plasma generation space S2, where high-frequency power is applied. The active species (e.g., radicals, etc.) of the nitride gas (e.g., NH3 gas) generated in the plasma generation space S2 are supplied to the processing space S1 through the communication holes 332. Specifically, NH3, NH2, NH, N, H, etc., are supplied to the processing space S1. Ions generated in the plasma generation space S2 are drawn towards the gas shower head 330, thereby suppressing the supply of ions to the processing space S1.

[0043] Thus, the remote plasma unit includes a gas shower head 330, an insulating side wall 340, a high-frequency electrode 350, and a high-frequency power supply 360. The remote plasma unit generates a nitride gas plasma (ammonia plasma) in the plasma generation space S2 and supplies radicals to the processing space S1 in the processing container 310.

[0044] Furthermore, the gas supply lines 335 and / or 336 may be connected to a purge gas supply source (not shown) and configured to supply purge gas.

[0045] The exhaust device 370 is connected to the exhaust port 310a of the processing container 310 and exhausts the gas from the processing space S1. The exhaust device 370 also adjusts the pressure in the processing space S1 by exhausting the gas from the processing space S1. Furthermore, the exhaust device 370 adjusts the pressure in the plasma generation space S2 by exhausting the gas from the plasma generation space S2 through the processing space S1 and the communication hole 332.

[0046] Furthermore, the plasma processing apparatus 100A has a plasma emission detection unit 200 that detects the emission of plasma generated in the plasma generation space S2. The plasma emission detection unit 200 includes a light receiving unit 210, an optical fiber 220, and a plasma monitor 230. Here, a window 345 made of, for example, quartz is provided in the insulating side wall 340. Plasma light generated in the plasma generation space S2 passes through the window 345. The light receiving unit 210 is provided outside the window 345. Plasma light generated in the plasma generation space S2 passes through the plasma compartment wall 32 and is incident on the light receiving unit 210. The plasma light incident on the light receiving unit 210 is input to the plasma monitor 230 via the optical fiber 220. The plasma monitor 230 acquires the emission spectrum in a predetermined wavelength range (in the example of Figure 6 described later, the wavelength range is 320 nm to 340 nm). The plasma monitor 230 then detects the emission intensity for each wavelength (resolution of the wavelength range).

[0047] The plasma processing apparatus 100 also has a control unit 380. The control unit 380 controls the operation of each part of the plasma processing apparatus 100, for example, the flow rate of the raw material gas supplied from the gas supply passage 335, the flow rate supplied from the gas supply passage 336, and exhaust control by the exhaust device 370 (pressure control of the plasma generation space S2). The control unit 380 also controls the on / off of high-frequency power by the high-frequency power supply 360, and controls the temperature of the substrate W by the heater of the susceptor 320.

[0048] Furthermore, the control unit 380 adjusts the plasma generation conditions based on the emission intensity of a predetermined wavelength (a wavelength of 336.0 nm derived from NH radicals, described later) detected by the plasma monitor 230. The plasma generation conditions include pressure control of the plasma generation space and / or power control of the high-frequency power.

[0049] The control unit 380 may be, for example, a computer. Furthermore, the computer program that controls the operation of each part of the plasma processing apparatus 100 is stored in a storage medium. The storage medium may be, for example, a flexible disk, compact disk, hard disk, flash memory, DVD, etc.

[0050] [Substrate processing using plasma processing equipment] Next, an example of substrate processing using the plasma processing apparatus 100 will be explained with reference to Figure 4. Figure 4 is a flowchart illustrating an example of substrate processing. Here, we will explain using the case where SiH2Cl2 gas is used as the source gas and NH3 gas is used as the nitriding gas, and a silicon nitride film (SiN) is deposited on the substrate W using the plasma ALD method.

[0051] First, the substrate W is prepared. In the plasma processing apparatus 100 shown in Figures 1 and 2, a wafer boat 5 holding the substrate is inserted into the processing container 1. In the plasma processing apparatus 100A shown in Figure 3, the substrate W is placed on the susceptor 320. The substrate W is also controlled to a predetermined film deposition temperature (for example, a temperature of 600°C or lower). In the plasma processing apparatus 100 shown in Figures 1 and 2, the substrate W is heated by a heating mechanism 50. In the plasma processing apparatus 100A shown in Figure 3, the substrate W is heated by a heater (not shown) of the susceptor 320. The pressure inside the processing container containing the substrate W is controlled to a predetermined level.

[0052] Next, the substrate processing shown in Figure 4 is started.

[0053] In step S101, a nitride gas (NH3) plasma is generated, and the active species of the nitride gas are supplied to the substrate W. This performs a nitriding treatment to nitride the substrate surface. Furthermore, in the second cycle and beyond, as described later, a nitriding treatment is performed to nitride the DCS adsorbed surface on which the source gas (DCS) has been adsorbed.

[0054] In the plasma processing apparatus 100 shown in Figures 1 and 2, the control unit 60 controls the on-off valve 22c to open it. This supplies nitride gas from the gas supply source 22a through the gas supply pipe 22 into the plasma compartment wall 32. The control unit 60 also controls the high-frequency power supply 35 to apply high-frequency power to the plasma electrode 33. This generates plasma within the plasma compartment wall 32, creating active species of nitride gas. The active species of nitride gas are supplied from the opening 31 to the substrate W in the processing container 1.

[0055] In the plasma processing apparatus 100A shown in Figure 3, the control unit 380 controls a nitride gas supply source (not shown) to supply nitride gas (NH3) from the gas supply passage 336 into the plasma generation space S2. The control unit 380 also controls a high-frequency power supply 360 to apply high-frequency power to the high-frequency electrode 350. As a result, plasma is generated in the plasma generation space S2, and active species of nitride gas are generated. The active species of nitride gas are supplied to the substrate W in the processing container 310 (processing space S1) from the communication hole 332.

[0056] In step S102, a purging process is performed. The purging process is a process of purging excess nitriding gas, etc., from the processing container.

[0057] In the plasma processing apparatus 100 shown in Figures 1 and 2, the control unit 60 controls the on-off valve 22c to close it and stop the supply of nitriding gas. As a result, the purge gas that is constantly supplied from the gas supply pipe 23 purges excess nitriding gas, gases generated in the nitriding reaction (S101), etc., in the processing container 1.

[0058] In the plasma processing apparatus 100A shown in Figure 3, the control unit 380 controls a purge gas supply source (not shown) to supply purge gas from the gas supply passage 335 and / or gas supply passage 336 into the processing container 310 (processing space S1). This allows the purge gas to purge excess nitriding gas, gases generated by the nitriding reaction (S101), etc., from the processing container 310 (processing space S1).

[0059] In step S103, the source gas (DCS) is supplied to the substrate W. This performs an adsorption process in which the source gas (DCS) is adsorbed onto the substrate surface, forming a DCS adsorption surface.

[0060] In the plasma processing apparatus 100 shown in Figures 1 and 2, the control unit 60 controls the on-off valve 21c to open it. This supplies raw material gas from the gas supply source 21a to the substrate W in the processing container 1 via the gas supply pipe 21.

[0061] In the plasma processing apparatus 100A shown in Figure 3, the control unit 380 controls a raw material gas supply source (not shown) and supplies raw material gas from the gas supply passage 335 to the substrate W inside the processing container 310 (inside the processing space S1) via the gas discharge section 331.

[0062] In step S104, a purging process is performed. The purging process is a process of purging excess raw material gas, etc., from the processing container.

[0063] In the plasma processing apparatus 100 shown in Figures 1 and 2, the control unit 60 controls the on-off valve 21c to close it and stop the supply of raw material gas. As a result, the purge gas that is constantly supplied from the gas supply pipe 23 purges excess raw material gas, gas generated by the adsorption reaction (S103), etc., in the processing container 1.

[0064] In the plasma processing apparatus 100A shown in Figure 3, the control unit 380 controls a purge gas supply source (not shown) to supply purge gas from the gas supply passage 335 and / or gas supply passage 336 into the processing container 310 (processing space S1). This allows the purge gas to purge excess raw material gas, gas generated by the adsorption reaction (S103), etc., from the processing container 310 (processing space S1).

[0065] In step S105, the control unit (60,380) determines whether a predetermined number of cycles have been repeated, considering steps S101 to S104 as one cycle of the ALD cycle. If the predetermined number of cycles has not been repeated (S105 - NO), the control unit (60,380) returns to step S101 and repeats the ALD cycle. If the predetermined number of cycles has been repeated (S105 - YES), the control unit (60,380) terminates the substrate processing (film deposition process).

[0066] This allows for the deposition of a silicon nitride (SiN) film of a desired thickness onto the substrate W.

[0067] Here, we will explain again the nitriding reaction (S101) and adsorption reaction (S103) in the substrate processing shown in Figure 4.

[0068] First, in step S101, active species (active nitride species) generated by ammonia plasma are supplied to the substrate W, and the substrate surface is nitrided. This creates "NH bonds" on the substrate surface.

[0069] Next, in step S103, the DCS gas supplied to the substrate surface undergoes a thermal reaction with the "NH bonds" on the substrate surface, and DCS is adsorbed while generating HCl. That is, the "-NH2" on the substrate surface is changed to "-NH-SiH2Cl", ​​and the generated HCl is exhausted. Depending on the film deposition conditions, the substrate surface may become "-N(SiH2Cl)2".

[0070] -NH2+ SiH2Cl2→ -NH-SiH2Cl + HCl↑ -NH2+ 2SiH2Cl2→ -N(SiH2Cl)2+ 2HCl↑

[0071] In step S101 of the next ALD cycle, active species (active nitride species) generated by the ammonia plasma are supplied to the substrate W to nitride the DCS adsorbed surface. When nitriding "-NH-SiH2Cl" on the substrate surface, the chemical adsorption sites for the nitride species are "Si-H" or "Si-Cl". Here, when the covalent bond concentrations of each bond in the resulting SiN film are analyzed by FT-IR, the Si-H bond concentration is below the detection limit. Therefore, the nitridation reaction at the chemical adsorption sites of the nitride species preferentially occurs at "Si-H" rather than "Si-Cl".

[0072] Here, the active nitride species, excluding the ions generated by the ammonia plasma, are electronically excited ammonia molecules NH3(3), vibrationally excited ammonia molecules NH3v, NH2 radicals, NH radicals, and N radicals. However, due to the short lifetimes of the diffusion process from the plasma generation section (plasma generation space within the plasma compartment wall 32 in Figure 1, and plasma generation space S2 in Figure 3) to the substrate W, the contributions of NH3(3) and N to the nitridation reaction can be ignored.

[0073] Vibrationally excited ammonia molecules (NH3v) are used as the nitriding species on the DCS adsorption surface. Furthermore, by using radicals with high reaction rates (those with unpaired electrons), it is desirable to further improve the efficiency of the nitriding reaction and enhance film quality (e.g., by reducing the wet etching rate). Specifically, optimizing the plasma generation conditions to generate a large amount of NH radicals and / or NH2 radicals in the plasma is desirable to further improve the efficiency of the nitriding reaction and enhance film quality.

[0074] [Process for adjusting plasma generation conditions] Next, the process of adjusting (optimizing) the plasma generation conditions will be explained using Figure 5. Figure 5 is a flowchart illustrating an example of the process of adjusting the plasma generation conditions. Note that the process shown in Figure 5 may be performed, for example, before starting the substrate processing shown in Figure 4.

[0075] In step S201, a nitride gas (NH3) plasma is generated. The control for generating the ammonia plasma is the same as the control in step S101, so a redundant explanation is omitted.

[0076] In step S202, the plasma emission spectrum is detected. Here, the plasma emission from the plasma generation space is received by the light receiving unit 210, and the emission intensity for each wavelength (resolution of the wavelength domain) is detected by the plasma monitor 230.

[0077] Figure 6 shows an example of an emission spectrum of ammonia plasma. The horizontal axis represents the wavelength of the spectrally separated emission spectrum. The vertical axis represents the emission intensity for each wavelength.

[0078] As shown in Figure 6, the emission spectrum of ammonia plasma includes wavelengths originating from NH2 radicals (326 nm), wavelengths originating from NH radicals (336.0 nm), wavelengths originating from N2 (337.1 nm), etc.

[0079] Figure 7 shows an example of the potential energy curve of an NH radical. The NH radical undergoes an electronic transition (A) indicated by the arrow. 3 Π→X 3 Σ - ) accompanies the emission of plasma light with a wavelength of 336.0 nm. Although not shown in the diagram, the NH2 radical undergoes an electronic transition (c 1 Π→a 1 In conjunction with Δ), it emits plasma light with a wavelength of 326.0 nm.

[0080] In step S203, the plasma generation conditions are adjusted so that the emission intensity at the emission wavelength (336.0 nm) originating from NH radicals increases (for example, reaches its maximum). Specifically, the plasma generation pressure and high-frequency power are adjusted within a range where particle generation and impurity contamination do not occur.

[0081] By adjusting the plasma generation conditions to increase the emission intensity at the emission wavelength (336.0 nm) derived from NH radicals, the amount of NH radicals generated can be increased. Then, by performing nitriding treatment (see S101 in Figure 4) using plasma generation conditions that increase the amount of NH radicals generated, the nitriding reaction on the DCS adsorption surface can be made more efficient, and the film quality of the silicon nitride (SiN) film can be improved.

[0082] Furthermore, there are multiple reaction pathways for the nitridation reaction of DCS adsorbed surfaces using ammonia plasma. By using NH radicals, which have a low activation energy, the nitridation reaction of the DCS adsorbed surface can be made more efficient, and the film quality of the silicon nitride (SiN) film can be improved.

[0083] Furthermore, the plasma generation conditions may be adjusted to maximize the emission intensity at the emission wavelength (336.0 nm) derived from NH radicals. This can further increase the amount of NH radicals generated, making the nitriding reaction on the DCS adsorption surface more efficient and further improving the film quality of the silicon nitride (SiN) film.

[0084] Furthermore, the plasma generation conditions are adjusted in multiple plasma processing devices so that the emission intensity at the emission wavelength (336.0 nm) originating from NH radicals is maximized in each device. This reduces inter-device differences in film deposition performance caused by the plasma.

[0085] Thus, the substrate processing shown in Figure 4 can be performed under plasma generation conditions adjusted by the process shown in Figure 5. Note that although the process shown in Figure 5 was described as being performed before starting the substrate processing shown in Figure 4, it is not limited to this.

[0086] The process shown in Figure 5 may be performed during the substrate processing shown in Figure 4. That is, when plasma is generated in step S101, the processes in steps S201 and S202 of Figure 5 may be performed, and the plasma generation conditions (pressure, high-frequency power) may be adjusted (S203) during the substrate processing.

[0087] Alternatively, the substrate processing for the first substrate W (see Figure 4) may involve performing steps S201 and S202 in Figure 5, adjusting the plasma generation conditions (pressure, high-frequency power) (S203) before starting the substrate processing for the second substrate W (see Figure 4), and then performing the substrate processing for the second substrate W (see Figure 4) under the adjusted plasma generation conditions.

[0088] [Reaction Analysis] Next, we will describe the reaction pathway of the nitridation reaction of the DCS adsorption surface by ammonia plasma.

[0089] Assuming the initial state in which DCS molecules are chemically adsorbed onto nitrogen atoms on the substrate surface is (SiH3)2N-SiH2Cl, a reaction analysis was performed on the reaction between NH radicals and NH2 radicals on the Si atoms of "-SiH2Cl".

[0090] For the reaction of NH radicals, the following reaction pathways (1) to (4) were assumed, and the analysis was carried out.

[0091] • H extraction reaction (1) (SiH3)2N-SiH2Cl + NH → (SiH3)2N-SiHCl + NH2

[0092] • Cl abstraction reaction (2) (SiH3)2N-SiH2Cl + NH → (SiH3)2N-SiH2+ NHCl

[0093] • Nitride reaction (3) (SiH3)2N-SiH2Cl + NH → (SiH3)2N-SiH(NH2)Cl (4) (SiH3)2N-SiH2Cl+NH → (SiH3)2N-SiH2(NHCl)

[0094] Reaction analysis of NH radicals revealed that reaction pathway (3) readily occurs with a low activation energy, while reaction pathways (1), (2), and (4) hardly occur at temperatures below 600°C. Furthermore, the results showed that hydrogen abstraction reactions (1) and chlorine abstraction reactions (2) by NH radicals do not occur.

[0095] Figure 8 is a model diagram illustrating the nitridation reaction of NH radicals onto chemically adsorbed DCS.

[0096] In the initial state, the DCS adsorption surface has "-SiH2Cl". Furthermore, "-SiH2Cl" has "Si-H bonds". In the transition state, NH radicals become oriented. The NH radicals then abstract hydrogen atoms from the "Si-H bonds" of "-SiH2Cl" (hydrogen abstraction reaction) and chemically adsorb as NH2 onto the Si atoms. This results in the final state. After the reaction, the number of "Si-H bonds" in the resulting SiN film decreases, and the number of "NH bonds" to which DCS is adsorbed increases.

[0097] Next, regarding the reaction of the NH2 radical, we assumed the following reaction pathways (5) to (9) and conducted an analysis.

[0098] • H extraction reaction (5) (SiH3)2N-SiH2Cl + NH2 → (SiH3)2N-SiHCl + NH3

[0099] • Cl abstraction reaction (6) (SiH3)2N-SiH2Cl + NH2 → (SiH3)2N-SiH2+ NH2Cl

[0100] • Nitride reaction (7) (SiH3)2N-SiH2Cl + NH2 → (SiH3)2N-SiH(NH2)Cl + H (8) (SiH3)2N-SiH2Cl + NH2 → (SiH3)2N-SiH2(NH2) + Cl (9) (SiH3)2N-SiH2Cl + NH2 → (SiH3)2N-SiH(NH2) + HCl

[0101] The reaction analysis of the NH2 radical revealed that the hydrogen abstraction reaction in reaction pathway (5) is the one with a low activation energy, is easily carried out, and has a stable final state. On the other hand, reaction pathways (6) to (9) were found to have high activation energies and / or have final states that are not the most stable states, making the reactions difficult to proceed.

[0102] As described above, the nitridation reaction by NH2 radicals on the DCS adsorption surface (reaction pathways (7) to (9)) is difficult to carry out. Therefore, the nitridation reaction on the DCS adsorption surface by radicals is mainly carried out by the nitridation reaction by NH radicals (especially reaction pathway (3)).

[0103] Furthermore, in the hydrogen abstraction reaction by radicals on the DCS adsorption surface (reaction pathways (1) and (5)), after hydrogen is abstracted from the "Si-H bond," an unpaired electron is generated on the Si atom. Therefore, the subsequently supplied NH2 and H can be chemically adsorbed onto this unpaired electron on the Si atom with a low activation energy.

[0104] (10) (SiH3)2N-SiHCl + NH2 → (SiH3)2N-SiH(NH2)Cl (11) (SiH3)2N-SiHCl + H → (SiH3)2N-SiH2Cl

[0105] Thus, after hydrogen abstraction occurs via reaction pathway (1) or reaction pathway (5), a portion is nitrided via reaction pathway (10). In other words, the nitriding reaction is carried out in two steps: reaction pathway (5) and reaction pathway (10). Furthermore, after hydrogen abstraction occurs via reaction pathway (1) or reaction pathway (5), the remaining portion returns to its original state through chemical adsorption of hydrogen atoms via reaction pathway (11).

[0106] It should be noted that the present invention is not limited to the configurations shown in the above embodiments, including combinations with other elements. These aspects can be modified without departing from the spirit of the present invention and can be appropriately determined according to their application. [Explanation of Symbols]

[0107] 1. Processing container 5. Wafer boat (substrate support section) 20 Gas Supply Department 21. Gas supply pipe (raw material gas supply section) 21a Gas supply source (raw material gas supply section) 21b Flow controller (raw material gas supply unit) 21c Shut-off valve (raw material gas supply section) 30 Plasma generation mechanism (remote plasma section) 60 Control Unit 100,100A Plasma Processing Equipment 200 Plasma emission detection unit 210 Light receiving section 220 optical fibers 230 Plasma Monitor 310 Processing container 320 Susceptor (Substrate support part) 330 Gas shower head (remote plasma unit, raw gas supply unit) 331 Gas discharge section (raw material gas supply section) 332 Communication holes (remote plasma section) 335 Gas supply line (raw material gas supply section) 336 Gas supply path (remote plasma section) 340 Insulating sidewall (remote plasma section) 350 High-frequency electrode (remote plasma section) 360 High-Frequency Power Supply (Remote Plasma Unit) 380 Control Unit S1 Processing Space S2 Plasma generation space W board

Claims

1. The process of generating ammonia plasma, A step of detecting the emission spectrum of the ammonia plasma, A step of adjusting the plasma generation conditions based on the emission intensity of the emission wavelength originating from NH radicals in the emission spectrum, A step of generating ammonia plasma under the adjusted plasma generation conditions and performing a nitriding treatment on the substrate, A step of supplying a raw material gas to the substrate and performing an adsorption process to adsorb the raw material gas onto the substrate, The process includes a step of repeating the cycle, with the nitriding treatment and the adsorption treatment being considered as one cycle. Substrate processing method.

2. The emission wavelength originating from NH radicals is 336.0 nm. The substrate processing method according to claim 1.

3. The step of adjusting the plasma generation conditions is: The plasma generation conditions are adjusted so that the emission intensity of the emission wavelength originating from the NH radical increases. The substrate processing method according to claim 1.

4. The step of adjusting the plasma generation conditions is: The plasma generation conditions are adjusted so that the emission intensity of the emission wavelength originating from the NH radical is maximized. The substrate processing method according to claim 1.

5. The step of adjusting the plasma generation conditions is: Adjust the plasma generation pressure and / or the power of the high-frequency power. The substrate processing method according to claim 1.

6. The nitriding treatment step is: The temperature of the substrate is 600°C or lower. The substrate processing method according to claim 1.

7. In the process of performing the adsorption treatment, The aforementioned raw material gas is one of monochlorosilane gas, dichlorosilane gas, or trichlorosilane gas. The substrate processing method according to claim 1.

8. A processing container having a processing space, A substrate support portion is provided within the processing container to support the substrate, A remote plasma unit that generates ammonia plasma in a plasma generation space and supplies radicals to the processing space, A raw material gas supply unit that supplies raw material gas to the processing space, A plasma emission detection unit for detecting the emission spectrum of the ammonia plasma generated in the plasma generation space, It comprises a control unit and, The control unit, A step of controlling the remote plasma unit to generate ammonia plasma in the plasma generation space, The steps include detecting the emission spectrum of the ammonia plasma using the plasma emission detection unit, A step of adjusting the plasma generation conditions based on the emission intensity of the emission wavelength originating from NH radicals in the emission spectrum, A step of controlling the remote plasma unit to generate ammonia plasma under the adjusted plasma generation conditions, supplying radicals to the processing space, and performing nitriding treatment on the substrate, A step of controlling the raw material gas supply unit to supply raw material gas to the processing space and performing an adsorption process to adsorb the raw material gas onto the substrate, The system is configured to perform a process of repeating the nitriding treatment and the adsorption treatment, with the cycle being considered as one cycle. Plasma processing equipment.

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