Plasma treatment method and substrate processing apparatus

Abstract

To provide a technique capable of reducing generation of particles by suppressing active species of nitrogen due to plasma when a nitride film is deposited.SOLUTION: Provided is a plasma processing method in which a nitride film is deposited on a substrate by using plasma. The plasma processing method includes the steps of: (a) supplying a plasma processing gas that includes a nitrogen-containing gas to a plasma processing space inside a processing container; and (b) supplying high-frequency power from a high-frequency power supply to an antenna disposed on a quartz portion exposed to the plasma processing space to generate the plasma in the plasma processing space, in performing the step of (a). In the step of (b), the average electron temperature of the plasma is lowered relative to the average electron density of the plasma by feeding, as the high frequency power, a pulse wave that repeats on and off to the antenna.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This disclosure relates to a plasma processing method and a substrate processing apparatus. [Background technology]

[0002] Patent Document 1 discloses a plasma processing method (film deposition method) for depositing a silicon oxide film on the surface of a substrate by generating plasma in the internal space of a processing container. In this plasma processing method, argon gas, oxygen gas, ammonia gas, etc. are supplied to the internal space of the processing container, and high-frequency power is supplied to an antenna at the top of the internal space to generate plasma in the internal space.

[0003] Nitrogen (N), a component of ammonia, becomes an active species when affected by high-energy electrons ionized within its internal space. This active nitrogen species can potentially damage quartz. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-135154 [Overview of the project] [Problems that the invention aims to solve]

[0005] This disclosure provides a technology that can suppress nitrogen reactive species when generating plasma and depositing a nitride film. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a plasma processing method for forming a nitride film on a substrate using plasma comprises: (a) a step of supplying a plasma processing gas containing nitrogen gas to a plasma processing space inside a processing vessel; and, during the execution of step (a), (b) a step of supplying high-frequency power from a high-frequency power supply to an antenna placed on a quartz portion exposed to the plasma processing space in order to generate the plasma in the plasma processing space, wherein in step (b), a pulse wave that repeatedly switches on and off is supplied to the antenna as the high-frequency power, thereby lowering the average electron density and average electron temperature of the plasma. Furthermore, step (b) includes a step of supplying a continuous wave of the high-frequency power from the high-frequency power supply to the antenna before the step of supplying the pulse wave, wherein the output value of the high-frequency power in the step of supplying the pulse wave is greater than the output value of the high-frequency power in the step of supplying the continuous wave. A plasma treatment method is provided. [Effects of the Invention]

[0007] According to one embodiment, when generating plasma and depositing a nitride film, the active species of nitrogen can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing an example of the configuration of a substrate processing apparatus according to one embodiment. [Figure 2] Figure 1 is a schematic plan view of the substrate processing apparatus. [Figure 3] This is a schematic cross-sectional view showing the configuration of a substrate processing apparatus that forms a plasma processing area. [Figure 4] This is a schematic plan view showing the plasma processing area of ​​a substrate processing device. [Figure 5] This is a schematic diagram illustrating a power supply circuit that provides high-frequency power. [Figure 6] This graph illustrates the electron density and electron temperature states of the plasma generated in the plasma processing space by a plasma processing method. [Figure 7] This flowchart shows the process for depositing a SiON film. [Figure 8] This is a timing chart showing an example of high-frequency power supply in the power supply process. [Figure 9]A graph and a table comparing the number of particles generated on a wafer by changing the conditions of the high-frequency power output from a high-frequency power source in a plasma treatment step.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for implementing the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components, and redundant descriptions may be omitted.

[0010] FIG. 1 is a schematic cross-sectional view showing a configuration example of a substrate processing apparatus 100 according to an embodiment. FIG. 2 is a schematic plan view of the substrate processing apparatus 100 of FIG. 1. In FIG. 2, for convenience of explanation, the illustration of the top plate is omitted. A plasma processing method according to an embodiment forms a predetermined film on the surface of a substrate using the substrate processing apparatus 100 shown in FIGS. 1 and 2. The substrate processing apparatus 100 performs a film formation process by an atomic layer deposition (ALD) method or a molecular layer deposition (MLD) method.

[0011] Examples of the substrate on which the film formation process is performed include semiconductor wafers such as silicon semiconductors, compound semiconductors, or oxide semiconductors (hereinafter, the substrate is also referred to as a wafer W). The wafer W may have recessed patterns such as trenches and vias.

[0012] Also, in the plasma processing method according to the present embodiment, a silicon oxynitride (SiON:SiO x N y ) film is formed on the surface of the wafer W. Note that the plasma processing method is not limited to forming a SiON film as long as it is a film formation process for forming a nitride film, and for example, a SiN film, a SiCN film, a SiBCN film, a SiOCN film, etc. may be used.

[0013] As shown in FIG. 1, the substrate processing apparatus 100 includes a substantially cylindrical processing chamber 1 and a rotary table 2 (substrate support unit) that rotates (revolves) the wafer W within the processing chamber 1. The substrate processing apparatus 100 also has a control unit 110 that controls each component of the apparatus.

[0014] The processing chamber 1 houses a plurality of wafers W therein and forms a SiON film on each wafer W. The processing chamber 1 includes a top plate 11 and a chamber body 12, and has a processing chamber inside for housing a plurality of wafers W and forming a SiON film on each wafer W. The processing chamber 1 has an annular seal member 13 on the outer peripheral wall of the upper surface of the chamber body 12, and the top plate 11 can be detachably and airtightly fixed to the chamber body 12. The diameter (inner diameter) of the processing chamber 1 in plan view is preferably designed to be about 1100 mm, for example.

[0015] A separation gas supply pipe 16 for supplying separation gas is connected to the central portion of the top plate 11. A purge gas supply pipe 17 for supplying a purge gas such as Ar gas is connected to the bottom surface portion 14 of the chamber body 12. A plurality of purge gas supply pipes 17 are provided along the circumferential direction of the bottom surface portion 14. The bottom surface portion 14 has an annular protrusion 12a at a position close to the outer peripheral surface of the core portion 21 that fixes the rotary table 2.

[0016] On the outer peripheral wall of the processing chamber 1, a transfer port 15 for transferring the wafer W between the rotary table 2 and the transfer arm 10 and a gate valve G for opening and closing the transfer port 15 are provided (see FIG. 2). The gate valve G airtightly seals the processing chamber of the processing chamber 1 in the closed state of the transfer port 15. The rotary table 2 transfers the wafer W to and from the transfer arm 10 by arranging a recess 24 for placing the wafer W at a position adjacent to the transfer port 15.

[0017] The rotary table 2 housed within the processing container 1 is fixed to a roughly disc-shaped core 21 in the center of the processing container 1 (see Figure 1). The core 21 is connected to a vertically extending rotating shaft 22, which is supported by a drive unit 23. The drive unit 23 rotates the rotary table 2 around the vertical axis (clockwise in Figure 2) via the rotating shaft 22. The diameter of the rotary table 2 is not particularly limited, but for example, if the diameter of the processing container 1 is 1100 mm, it is preferable to have a diameter of about 1000 mm.

[0018] The drive unit 23 includes an encoder 25 that detects the rotation angle of the rotating shaft 22. The rotation angle of the rotating shaft 22 detected by the encoder 25 is transmitted to the control unit 110, which uses it to determine the position of the wafer W placed in each recess 24 on the rotary table 2.

[0019] The lower end of the rotating shaft 22, the drive unit 23, and the encoder 25 are housed in a case body 26. The case body 26 is airtightly attached to the bottom surface 14 of the processing container 1. A purge gas supply pipe 27, which supplies purge gas to the area below the rotary table 2, is also connected to the case body 26.

[0020] The rotary table 2 has multiple circular recesses 24 on its surface (six in this embodiment) capable of accommodating a wafer W with a diameter of, for example, 300 mm (see also Figure 2). The multiple recesses 24 are arranged at equal intervals along the rotation direction of the rotary table 2 (clockwise in Figure 2). Each recess 24 has an inner diameter slightly larger than the diameter of the wafer W (approximately 1 mm to 4 mm). The depth of the recess 24 is set to be greater than or equal to the thickness of the wafer W.

[0021] Multiple through holes (for example, three) not shown are formed in the bottom surface of the recess 24 for passing through multiple lifting pins (not shown). Each lifting pin is located at a wafer W transfer position near the transport port 15 and moves up and down by a lifting mechanism (not shown). Each lifting pin rises after the transport arm 10 holding the wafer W enters to receive the wafer W, and lowers after the transport arm 10 retracts to place the wafer W in the recess 24. Furthermore, each lifting pin raises the wafer W after substrate processing and then transfers the wafer W to the transport arm 10 that enters afterward.

[0022] As shown in Figure 2, the substrate processing apparatus 100 has multiple gas nozzles positioned above the passage range of each recess 24. Each gas nozzle extends along the normal to the rotation direction of the rotary table 2 and is installed at intervals from one another along the circumferential direction of the processing container 1. In this embodiment, the multiple gas nozzles are a first processing gas nozzle 31, a second processing gas nozzle 32, third processing gas nozzles 33-35, and separation gas nozzles 41, 42.

[0023] The first processing gas nozzle 31, the second processing gas nozzle 32, the third processing gas nozzles 33-35, and the separation gas nozzles 41 and 42 are arranged in the processing chamber between the rotary table 2 and the top plate 11. Each of the first processing gas nozzle 31, the second processing gas nozzle 32, and the separation gas nozzles 41 and 42 extends linearly along the radial direction from the outer peripheral wall of the processing container 1 toward the central region C, and is fixed parallel (horizontally) to the rotary table 2. In Figure 2, the third processing gas nozzles 33-35, the separation gas nozzle 41, the first processing gas nozzle 31, the separation gas nozzle 42, and the second processing gas nozzle 32 are arranged in this order clockwise from the transport port 15.

[0024] The first processing gas nozzle 31 has a plurality of gas holes (not shown) on its lower side (the side facing the rotary table 2), and ejects the first processing gas through each gas hole into the first processing area P1 on the lower side of the processing chamber. The first processing gas nozzle 31 is connected to the supply source of the first processing gas outside the processing container 1 via a flow rate adjustment valve and an on / off valve (neither shown). When forming a SiON film, the first processing gas nozzle 31 ejects, for example, a silicon-containing gas as the first processing gas onto the wafer W.

[0025] A nozzle cover 40 is provided above the first processing gas nozzle 31. The nozzle cover 40 covers the top and both sides of the first processing gas nozzle 31, allowing the first processing gas to flow along the wafer W and guiding the separated gas to flow along the top plate 11 of the processing container 1, avoiding the wafer W.

[0026] The second processing gas nozzle 32 has a plurality of gas holes on its lower side (the side facing the rotary table 2), and ejects the second processing gas through each gas hole into the second processing area P2 on the lower side of the processing chamber. The second processing gas nozzle 32 is connected to the supply source of the second processing gas outside the processing container 1 via a flow control valve and an on / off valve (neither of which are shown). When forming a SiON film, the second processing gas nozzle 32 ejects, for example, an oxygen-containing gas (O2, O3, or a mixture thereof, etc.) as the second processing gas.

[0027] The third processing gas nozzles 33-35 eject the third processing gas into the third processing area P3 of the processing chamber. The third processing area P3 is the area where plasma processing is performed on the wafer W, and will hereafter be referred to as the plasma processing area P3. The configuration provided in this plasma processing area P3 will be described in detail later.

[0028] The separation gas nozzles 41 and 42 form separation regions D1 and D2, which separate the first processing region P1 from the second processing region P2, and the third processing region P3 from the first processing region P1. Each of the separation gas nozzles 41 and 42 has multiple gas holes on its lower side (the side facing the rotary table 2), and a separation gas such as an inert gas or a noble gas is injected into the separation regions D1 and D2 through each gas hole. The separation gas nozzles 41 and 42 are connected to a supply source of separation gas outside the processing container 1 via a flow control valve and an on / off valve (neither of which are shown).

[0029] The underside of the top plate 11 (see Figure 1) of the processing container 1 in the separation regions D1 and D2 is provided with a roughly fan-shaped convex portion 4. The convex portion 4 has a groove (not shown) that extends radially in the circumferential center, and each separation gas nozzle 41, 42 is housed within this groove.

[0030] Returning to Figure 1, a projection 5 is provided in the center of the lower surface of the top plate 11, which is formed in a substantially annular shape along the circumferential direction, continuous with the portion of the convex portion 4 on the central region C side. The lower surface of the projection 5 is formed at the same height as the lower surface of the convex portion 4. A labyrinth structure 51 is provided closer to the rotation center of the rotary table 2 than the projection 5 and above the core portion 21, in order to suppress the mixing of each gas in the central region C.

[0031] Furthermore, as shown in Figures 1 and 2, the processing container 1 is equipped with an annular side ring 18, which is a cover body, located outside and below the rotary table 2. A groove-shaped gas flow path 18a is formed inside the side ring 18, through which gas can flow.

[0032] The side ring 18 has a first exhaust port 61 and a second exhaust port 62 on its upper surface. The first exhaust port 61 is formed between the first processing gas nozzle 31 and the separation region D1. The second exhaust port 62 is formed between the plasma processing region P3 and the separation region D2. The first exhaust port 61 mainly exhausts the first processing gas and separation gas, and the second exhaust port 62 mainly exhausts the third processing gas and separation gas. As shown in Figure 1, an exhaust pipe 63 is connected to the gas flow path 18a via an exhaust port on the bottom surface 14 of the processing container 1. A pressure adjustment unit 64 such as a butterfly valve and a vacuum exhaust mechanism 65 such as a vacuum pump are connected to the exhaust pipe 63.

[0033] Furthermore, the substrate processing apparatus 100 is equipped with a heater unit 7 in the space between the bottom surface 14 of the processing container 1 and the rotary table 2. The heater unit 7 is housed in a cover body 71 supported by a protrusion 12a of the container body 12, and heats the wafer W on the rotary table 2 to, for example, room temperature to about 700°C.

[0034] Furthermore, the control unit 110 of the substrate processing apparatus 100 can be a control computer having one or more processors 111, memory 112, input / output interfaces, and electronic circuits (not shown). The processor 111 is a combination of one or more of the following: CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), circuit consisting of multiple discrete semiconductors, etc. The memory 112 includes volatile memory and non-volatile memory (for example, a combination of one or more of the following: compact disc, DVD (Digital Versatile Disc), hard disk, flash memory, etc.). The processor 111 operates the substrate processing apparatus 100 to perform film deposition by reading and executing recipes such as programs and process conditions stored in the memory 112.

[0035] Next, the configuration of the plasma processing area P3 of the substrate processing apparatus 100 will be described. As shown in Figure 2, the substrate processing apparatus 100 is equipped with a plasma source 80 located above the plasma processing area P3. The plasma source 80 is formed in a substantially fan shape in plan view and is installed so as to straddle the diameter portion of the recess 24 (wafer W) on the rotary table 2.

[0036] Figure 3 is a schematic cross-sectional view showing the configuration of the substrate processing apparatus 100 that forms the plasma processing region P3. Figure 4 is a schematic plan view showing the plasma processing region P3 of the substrate processing apparatus 100. In Figure 4, for ease of understanding, the third processing gas nozzles 33-35 are shown with solid lines, and the configuration of the processing vessel 1 and the plasma source 80 is shown with dashed lines (two-dot dashed lines). As shown in Figures 3 and 4, the plasma processing region P3 is configured as an inductively coupled plasma (ICP) type, with high frequency output from the plasma source 80 above the processing vessel 1. Inside the processing vessel 1, a plasma processing space 99 is formed between the plasma source 80 and the rotary table 2, where the third processing gas ejected from the third processing gas nozzles 33-35 is converted into plasma.

[0037] The plasma source unit 80 includes an antenna 83 that forms an induced electric field in the plasma processing space 99. The antenna 83 is installed so as to be airtightly partitioned from the internal region of the processing container 1. In a plan view, the antenna 83 has a flattened coil shape that follows the rectangular shape of the plasma source unit 80 (see also Figure 2). As an example, the antenna 83 is formed by winding a metal wire or the like multiple times (for example, three times) around a vertical axis.

[0038] The antenna 83 is connected to the high-frequency power supply 85 via a matching unit 84 outside the processing vessel 1. The plasma source unit 80 also has connecting electrodes 86 for electrically connecting the antenna 83, the matching unit 84, and the high-frequency power supply 85. The antenna 83 may be provided with a configuration that allows it to be folded up and down, an up and down movement mechanism that allows the antenna 83 to be automatically folded up and down, a mechanism that allows the central part of the rotary table 2 to move up and down, etc. (not shown) as needed.

[0039] A roughly fan-shaped opening 11a is formed in the top plate 11 above the third processing gas nozzles 33-35 in a plan view (see Figure 3). The plasma source unit 80 has a housing 90 containing an antenna 83 installed via an annular member 82 that runs around the edge of the opening 11a in the top plate 11. A sealing member 11b, such as an O-ring, is provided between the annular member 82 and the housing 90. The plasma source unit 80 is assembled to the processing container 1 by fixing a frame-shaped pressing member 91 along the boundary between the annular member 82 and the housing 90 to the top plate 11 with fixing means such as bolts, while the annular member 82 and the housing 90 are fitted into the opening 11a. This hermetically seals the ceiling side of the plasma processing space 99.

[0040] In this embodiment, the housing 90 is a quartz portion formed of quartz, and the antenna 83 is positioned below the top plate 11. The housing 90 has a flange portion 90a that protrudes along the circumferential direction on its upper edge, and the central part is recessed toward the internal area of ​​the processing container 1 below, forming a box with a concave shape in cross-section. When the wafer W is positioned below the housing 90, the housing 90 is positioned so as to straddle the wafer W in the radial direction of the rotary table 2. The lower surface of the housing 90 is an opposing surface 93 facing the rotary table 2 in the plasma processing space 99.

[0041] On the side of the housing 90 opposite to the opposing surface 93, a Faraday shield 95 and an insulating plate 94 are laminated. The Faraday shield 95 is made of a conductive plate (metal plate). The insulating plate 94 ensures insulation between the Faraday shield 95 and the antenna 83, and is made of quartz or the like.

[0042] The housing 90 has a projection 92 that protrudes downward from the opposing surface 93 toward the rotary table 2. The projection 92 surrounds the plasma processing space 99 on the lower side of the housing 90 along the circumferential direction. The third processing gas nozzles 33 to 35 are arranged in the plasma processing space 99, which is surrounded by the opposing surface 93 of the housing 90, the inner circumferential surface of the projection 92, and the upper surface of the rotary table 2. The projection 92 located at the base end of the third processing gas nozzles 33 to 35 (on the inner wall side of the processing container 1) is cut out to conform to the outer shape of the third processing gas nozzles 33 to 35.

[0043] The third processing gas nozzles 33-35 eject a plasma processing gas, which is the third processing gas, in conjunction with the plasma source 80. This generates plasma in the plasma processing space 99. The third processing gas nozzles 33-35 eject a rare gas, nitrogen-containing gas, etc., for plasma generation, either alone or in mixture. Examples of rare gases include argon (Ar) gas and helium (He) gas. An example of a nitrogen-containing gas is ammonia (NH3) gas. The third processing gas nozzles 33-35 may also be configured to eject other gases (for example, oxygen-containing gases such as O2 and O3, or hydrogen-containing gases such as H2) in addition to the rare gas and nitrogen-containing gas.

[0044] Specifically, the third processing gas nozzles 33-35 include a base nozzle 33, an outer nozzle 34, and an axial nozzle 35 (see Figure 4). The base nozzle 33 is a gas nozzle that supplies plasma processing gas to the entire surface of the wafer W and is positioned upstream of the rotation direction of the rotary table 2 in the plasma processing space 99 (near the projection 92). The base nozzle 33 extends linearly along the radial direction of the rotary table 2 and reaches near the central region C of the processing container 1.

[0045] The base nozzle 33 has multiple gas holes 33a facing the downstream side in the rotational direction of the rotary table 2. Each gas hole 33a is arranged at equal intervals along the longitudinal direction of the base nozzle 33 at the installation position of the plasma source 80 (below the opposing surface 93). Each gas hole 33a ejects plasma processing gas parallel to the plane direction (horizontal direction) of the opposing surface 93 of the plasma source 80. Alternatively, the multiple gas holes 33a may be formed at an angle downward (towards the rotary table 2) with respect to the horizontal direction, and the plasma processing gas may be ejected toward the rotary table 2.

[0046] The outer nozzle 34 is a nozzle for supplying plasma processing gas intensively to the outer region of the wafer W, and is provided in the plasma processing space 99 near the upstream side in the rotational direction of the rotary table 2. The outer nozzle 34 has a radial portion that extends a short distance from the outer peripheral wall of the processing container 1 toward the central region C, and an outer portion that bends near the outer peripheral wall and extends linearly in a clockwise direction. The outer nozzle 34 is provided with one or more gas holes 34a in the outer portion. The multiple gas holes 34a are formed, for example, to face the central region C and to look diagonally downward (towards the rotary table 2).

[0047] The axial nozzle 35 is a nozzle for supplying plasma processing gas intensively to the wafer W near the central region C of the processing container 1, and is provided in the plasma processing space 99 near the downstream side in the rotational direction of the rotary table 2. The axial nozzle 35 has a radial portion that extends radially from the outer peripheral wall of the processing container 1 toward the central region C, and an axial portion that bends near the central region C and extends linearly in a counterclockwise direction (opposite to the rotational direction of the rotary table 2). The axial nozzle 35 is provided with one or more gas holes 35a in the axial portion. The multiple gas holes 35a are formed, for example, to face the outer peripheral wall of the processing container 1 and to look diagonally downward (towards the rotary table 2).

[0048] The flow rates (supply amounts) of Ar gas and NH3 gas that constitute the plasma processing gas may differ from each other in the base nozzle 33, outer nozzle 34, and axial nozzle 35. For example, the substrate processing apparatus 100 can be configured to supply NH3 gas from the base nozzle 33 and outer nozzle 34, while not supplying NH3 gas from the axial nozzle 35. Alternatively, the base nozzle 33, outer nozzle 34, and axial nozzle 35 may be configured to eject gas at the same flow rate from each other. The substrate processing apparatus 100 may also be configured without one or both of the outer nozzle 34 and axial nozzle 35.

[0049] Furthermore, the third processing gas nozzles 33 to 35 are connected to the processing gas supply unit 37 outside the processing container 1 (see Figure 3). For example, the processing gas supply unit 37 has an Ar gas source 371, an NH3 gas source 372, a base nozzle buffer section 373, an outer nozzle buffer section 374, and an axial nozzle buffer section 375 for supplying plasma processing gas. A flow regulator, on / off valve, etc., not shown, are provided between the Ar gas source 371 and the NH3 gas source 372 and the base nozzle buffer section 373, the outer nozzle buffer section 374, and the axial nozzle buffer section 375.

[0050] The base nozzle buffer section 373 mixes Ar gas from the Ar gas source 371, NH3 gas from the NH3 gas source 372, etc., at an appropriate flow rate ratio and supplies it to the base nozzle 33. The outer nozzle buffer section 374 mixes Ar gas from the Ar gas source 371, NH3 gas from the NH3 gas source 372, etc., at an appropriate flow rate ratio and supplies it to the outer nozzle 34. The shaft-side nozzle buffer section 375 mixes Ar gas from the Ar gas source 371, NH3 gas from the NH3 gas source 372, etc., at an appropriate flow rate ratio and supplies it to the shaft-side nozzle 35.

[0051] Figure 5 is a schematic diagram illustrating a power supply circuit for supplying high-frequency power. As shown in Figure 5, the substrate processing apparatus 100 has a high-frequency power supply 85, a matching circuit 84, an antenna 83, and a blocking capacitor 87 connected in series, in order from the power supply side to the ground side. The matching circuit 84 has multiple variable capacitance capacitors and / or inductors inside and performs impedance matching when an induced electric field is formed by the antenna 83.

[0052] The high-frequency power supply 85 is equipped with an oscillator capable of outputting a high-frequency power of 13.56 MHz and an output value of 500 W to 5 kW (5000 W). Furthermore, the high-frequency power supply 85 is configured to output both continuous and pulsed high-frequency power. In particular, when outputting pulsed high-frequency power, it is desirable that the high-frequency power supply 85 allows adjustment of the duty cycle over a range of 10% to 99.9%.

[0053] The high-frequency power supply 85 is connected to the control unit 110 in a communicative manner and outputs adjusted high-frequency power to the antenna 83 based on control commands transmitted from the control unit 110. The control commands include information such as the output value of the high-frequency power, the duty cycle of the pulse wave, and the output timing of the continuous wave and pulse wave. As a result, the substrate processing apparatus 100 can appropriately control the induced electric field of the plasma processing space 99 at the control unit 110.

[0054] The substrate processing apparatus 100, configured as described above, is configured to output high-frequency pulse waves from the high-frequency power supply 85 during the period when plasma processing is actually applied to the wafer W in the film deposition process. The significance of outputting pulse waves from this high-frequency power supply 85 will be explained below with reference to Figure 6. Figure 6 is a graph illustrating the electron density and electron temperature of the plasma generated in the plasma processing space 99 by the plasma processing method, where (A) is when a continuous wave is supplied and (B) is when a pulse wave is supplied.

[0055] As shown in Figure 6(A), in the plasma processing space 99, the electron density (Ne) and electron temperature (Te) of the plasma fluctuate in accordance with the high-frequency power supplied to the antenna 83. Specifically, when a continuous wave is output from the high-frequency power supply 85 to the antenna 83, the electron density (Ne) and electron temperature (Te) of the plasma processing space 99 increase as the high-frequency power rises from zero (off) to a predetermined output value (e.g., 4kW: on). At this time, the electron temperature (Te) rises sharply, roughly in conjunction with the switching from off to on of the high-frequency power. Electrons in the plasma readily receive energy from the induced electric field and experience little energy loss even when colliding with other particles. Therefore, the electron temperature (Te) easily follows changes in high-frequency power. On the other hand, the electron density (Ne) rises based on the ionization of the plasma processing gas in the plasma, and therefore lags behind the rise in high-frequency power.

[0056] Here, when the electron temperature is high, electrons in the plasma collide with nitrogen (N), generating active nitrogen species. When these active nitrogen species collide with the housing 90 (quartz part), they damage the quartz, causing particle generation. However, if the output of the high-frequency power is lowered to suppress the electron temperature, the ionization of the plasma processing gas also decreases. To suppress particles resulting from quartz damage, it is necessary to reduce the electron temperature while maintaining a high electron density.

[0057] As shown in Figure 6(B), when a pulse wave is output that repeatedly switches high-frequency power on and off, the electron density (Ne) and electron temperature (Te) decrease when the high-frequency power is turned off. However, the attenuation rate of electron temperature (Te) decreases rapidly as the induced electric field disappears when the high-frequency power is turned off. On the other hand, the attenuation rate of electron density (Ne) decreases at a much smaller rate than the attenuation rate of electron temperature (Te). Therefore, by utilizing the difference in attenuation between electron temperature (Te) and electron density (Ne) when the high-frequency power is turned off, it becomes possible to reduce the electron temperature while maintaining the electron density.

[0058] Specifically, due to the pulsed wave of high-frequency power, the electron temperature (Te) starts to repeat large amplitudes, and the average electron density (average Ne), which is its average value, decreases. On the other hand, due to the pulsed wave of high-frequency power, the electron density (Ne) gradually decreases from a high density state and starts to repeat small amplitudes, and its average value, the average electron temperature (average Te), can be maintained at a high level. Therefore, by using the pulsed wave of high-frequency power, the substrate processing apparatus 100 can suppress particles associated with quartz damage by significantly reducing the average electron temperature with respect to the average electron density.

[0059] In order to accurately control the average electron density and average electron temperature in the plasma processing space 99, the control unit 110 of the substrate processing apparatus 100 commands the duty of the high-frequency power supplied from the high-frequency power source 85 to output a pulsed wave. The duty of the pulsed wave of high-frequency power can be obtained by the following formula (1). Duty = T ON / (T ON + T OFF ) Here, T ON is the on-period of the high-frequency power, and T OFF is the off-period of the high-frequency power.

[0060] The control unit 110 can set the duty of the pulsed wave of high-frequency power in the range of 10% to 99.9%. However, as the actual duty of the pulsed wave, it is preferably set in the range of 66.7% to 99.9%. When the duty of the pulsed wave is less than 66.7%, while the attenuation of the electron temperature (Te) decreases, the attenuation of the electron density (Ne) increases, so the average electron density tends to decrease.

[0061] On the other hand, if the duty of the pulsed wave is 66.7% or more, while the electron temperature (Te) significantly decreases, the high-frequency power turns on at a stage where the decrease in the electron density (Ne) is small. Therefore, it is possible to maintain the average electron density at a sufficiently high value. Note that the control unit 110 not only commands the duty of the pulsed wave but also the on-period T ON and the off-period T OFFA configuration that commands the following is also acceptable: Duty, On period T ON and off period T OFF This can be a user-configurable setting.

[0062] The substrate processing apparatus 100 according to this embodiment is basically configured as described above, and its operation (film formation process) will be explained below.

[0063] Figure 7 is a flowchart showing the process of forming an SiON film, where (A) is a flowchart showing each step of the film formation process, and (B) is a flowchart showing the plasma treatment method for the plasma annealing step S2. After placing the wafer W in each recess 24 of the rotary table 2 in the processing container 1, the control unit 110 of the substrate processing apparatus 100 sequentially performs the SiO2 film formation step S1 and the plasma annealing step S2 as a substrate processing method, as shown in Figure 7(A).

[0064] In the SiO2 film formation process S1, the control unit 110 controls the pressure inside the processing container 1 to a predetermined level using the pressure adjustment unit 64 and the vacuum evacuation mechanism 65, and while rotating the rotary table 2, heats the wafer W to a predetermined temperature using the heater unit 7. At this time, the control unit 110 supplies separation gas (for example, Ar gas) from the separation gas nozzles 41 and 42.

[0065] Furthermore, the control unit 110 supplies a silicon-containing gas, which is the first processing gas, from the first processing gas nozzle 31. As a result, the silicon-containing gas adheres to the surface of the wafer W in the first processing region P1.

[0066] Furthermore, the control unit 110 supplies a second processing gas, an oxygen-containing gas, from the second processing gas nozzle 32. As a result, in the second processing region P2, the silicon-containing gas on the wafer W, which has moved with the rotation of the rotary table 2, reacts with the oxygen-containing gas. Consequently, a molecular layer of SiO2, a thin film component, is formed and deposited on the wafer W.

[0067] The control unit 110 then continues the rotation of the rotary table 2, repeating the deposition of silicon-containing gas onto the surface of the wafer W and the reaction between the silicon-containing gas and the oxygen-containing gas. As a result, an SiO2 film of the desired thickness is formed on the surface of the wafer W. When the thickness of the SiO2 film reaches the desired thickness, the control unit 110 terminates the SiO2 film formation process S1.

[0068] Next, in the plasma annealing process S2, the control unit 110 performs plasma processing on each wafer W in the plasma processing area P3 of the processing vessel 1. As shown in Figure 7(B), the control unit 110 controls the pressure inside the processing vessel 1 to a predetermined level using the pressure adjustment unit 64 and the vacuum exhaust mechanism 65, and rotates the rotary table 2 on which each wafer W is placed (step S21). At this time, the control unit 110 also heats the wafer W to a predetermined level using the heater unit 7 and supplies separation gas from the separation gas nozzles 41 and 42.

[0069] Then, the control unit 110 controls the processing gas supply unit 37 to perform a gas supply process in which plasma processing gas (Ar gas, NH3 gas) is supplied from the third processing gas nozzles 33 to 35 to the plasma processing space 99 (step S22). Furthermore, while the gas supply is continuing, the control unit 110 supplies high-frequency power from the high-frequency power supply 85 to the antenna 83 to perform a power supply process in which plasma is generated in the plasma processing space 99 (step S23). The plasma in the plasma processing space 99 modifies the SiO2 film deposited on the wafer W, thereby generating an SiON film.

[0070] Figure 8 is a timing chart showing an example of high-frequency power supply in the power supply process. As shown in Figure 8, in the power supply process, the control unit 110 first performs an initial step of supplying a continuous wave of high-frequency power from the high-frequency power supply 85 to the antenna 83. This excites Ar gas in the plasma processing space 99, allowing the plasma to be rapidly ignited. The high-frequency power for the initial step of supplying the continuous wave should be set to, for example, 2 kW. By using low high-frequency power in the initial step, the substrate processing apparatus 100 can suppress damage to the quartz constituting the housing 90.

[0071] When the plasma processing space 99 reaches a point where plasma is stably generated, the control unit 110 continues to supply the plasma processing gas and transitions to a plasma processing step in which it supplies high-frequency pulse waves from the high-frequency power supply 85. Preferably, the output value of the high-frequency power in this plasma processing step is set to 1.5 times or more the output value of the high-frequency power in the initial step. For example, in Figure 8, the control unit 110 sets the output value of the high-frequency power in the plasma processing step to 4kW, which is twice the output value of the initial step. As a result, the substrate processing apparatus 100 can efficiently perform plasma processing on each wafer W even when supplied with high-frequency pulse waves.

[0072] By performing the above power supply process, the substrate processing apparatus 100 can lower the average electron temperature in the plasma processing space 99 while maintaining the average electron density of the plasma. Specifically, by maintaining a high average electron density, it becomes possible to perform plasma processing on the SiO2 film on the wafer W and smoothly modify the SiO2 film into a SION film. On the other hand, the substrate processing apparatus 100 can reduce damage to the quartz by lowering the average electron temperature, thereby suppressing particles generated as a result of quartz damage.

[0073] Returning to Figure 7(A), when the control unit 110 of the substrate processing apparatus 100 completes the plasma annealing process S2, it controls the processing gas supply unit 37 to stop the plasma processing gas and also stops supplying high-frequency power to the plasma source unit 80. After that, the control unit 110 removes the processed wafer W from the processing container 1 and completes the film formation process. In the substrate processing method of the above embodiment, the case in which the SiO2 film formation process S1 and the plasma annealing process S2 are performed sequentially once each has been described, but the method is not limited to this, and the SiO2 film formation process S1 and the plasma annealing process S2 may be repeated alternately multiple times. In addition, in the substrate processing method, the supply of silicon-containing gas in the first processing area P1, the supply of oxygen-containing gas in the second processing area P2, and the plasma modification in the plasma processing area P3 may be performed simultaneously while each wafer W is rotated.

[0074] [Examples] An experiment was conducted to confirm the effectiveness of the plasma processing method described above. Figure 9 is a graph and table comparing the number of particles generated on the wafer W when the conditions of the high-frequency power output from the high-frequency power supply 85 were changed during the plasma processing step.

[0075] In the bar graph of Figure 9, the horizontal axis represents each pattern of high-frequency power conditions, and the vertical axis represents the number of particles generated on the wafer W during plasma processing. In this experiment, the process conditions were as follows: the wafer W was heated to 400°C, and the pressure inside the processing vessel 1 was adjusted to 1.5 Torr (200 Pa). Furthermore, the plasma processing method was performed with the wafer W placed in the plasma processing space 99 with the rotation of the wafer W by the rotary table 2 stopped. The plasma processing gases supplied to the plasma processing space 99 were Ar gas and NH3 gas.

[0076] As can be seen from the experimental results shown in Figure 9, when a continuous wave of high-frequency power is supplied, the number of particles generated on the wafer W increases. In particular, when the high-frequency power is 3kW or 4kW, the number of particles increases significantly. In the substrate processing apparatus 100, which performs a plasma processing method while rotating the wafer W with a rotary table 2, the processing efficiency can be improved by setting the high-frequency power value to a high value, but the increase in particles at power values ​​such as 3kW and 4kW becomes a problem.

[0077] In contrast, when a high-frequency pulsed wave is supplied, the number of particles is reduced compared to when a continuous wave is supplied. Therefore, it can be said that by supplying a high-frequency pulsed wave, damage to the quartz is reduced and particles can be suppressed. In particular, the on-period T of the pulsed wave ON If the off period is 1 msec and T OFF When the duration is 0.5 msec (Duty is 66.7%), it can be seen that the particles are sufficiently suppressed. ON It can be inferred that shortening the on-period T of the high-frequency pulse wave reduces the period during which the plasma electron temperature (Te) is high, thereby reducing the damage inflicted by the N-active species on the quartz. Therefore, the plasma treatment method is based on the on-period T of the high-frequency power pulse wave. ON and off period T OFF By appropriately configuring these settings, it is possible to achieve plasma processing with reduced particle generation.

[0078] The substrate processing apparatus 100 and plasma processing method of this disclosure are not limited to the embodiments described above, and can be modified in various ways. For example, in the embodiments described above, a substrate processing apparatus 100 is described in which a plasma processing method is performed while rotating a plurality of wafers W using a rotary table 2, but the plasma processing method of this disclosure can also be applied to a substrate processing apparatus in which a single wafer W is placed on a mounting table (not shown).

[0079] The plasma processing method may be configured to vary the output value of the high-frequency power during the plasma processing step in which a pulse wave of high-frequency power is supplied. For example, by gradually increasing the high-frequency power at the start of pulse wave supply, it is possible to suppress local increases in electron density and electron temperature. As described above, the high-frequency power supply 85 can adjust the high-frequency power in the range of 500W to 5kW, so it is possible to output high-frequency power at an appropriate output value depending on the situation.

[0080] Furthermore, the plasma processing method may also be configured to output a pulsed wave immediately after the plasma annealing process, without outputting a continuous wave of high-frequency power. Even in this case, the high-frequency power of the pulsed wave can ignite the plasma in the plasma processing space 99.

[0081] The technical ideas and effects of this disclosure, as described in the embodiments above, are described below.

[0082] A first aspect of this disclosure is a plasma processing method for depositing a nitride film on a substrate (wafer W) using plasma, comprising: (a) supplying a plasma processing gas containing nitrogen gas to a plasma processing space 99 inside a processing container 1; and, during the execution of step (a), (b) supplying high-frequency power from a high-frequency power supply 85 to an antenna 83 located in a quartz section (housing 90) exposed to the plasma processing space 99 in order to generate plasma in the plasma processing space 99, wherein in step (b), pulse waves that repeatedly switch on and off are supplied to the antenna 83 as high-frequency power, thereby lowering the average electron density and the average electron temperature relative to the average electron density of the plasma.

[0083] The plasma treatment method described above suppresses the generation of nitrogen reactive species caused by ionized electrons by supplying high-frequency pulsed power when depositing a nitride film using plasma. In other words, the plasma treatment method can lower the average electron temperature while maintaining the average electron density by supplying pulsed power. Therefore, damage to the quartz part (housing 90) caused by nitrogen becoming an reactive species due to the effects of high electron temperature is suppressed. As a result, the plasma treatment method can significantly reduce the generation of particles caused by the abrasion of quartz.

[0084] Furthermore, in step (b), the duty cycle of the pulse wave is set to a range of 66.7% to 99.9%. This allows the plasma processing method to sufficiently lower the average electron temperature while maintaining the average electron density.

[0085] Furthermore, in step (b), a high-frequency power output value in the range of 500W to 5000W is supplied. This allows the plasma processing method to stably generate plasma in the plasma processing space 99, even when supplying pulsed waves of high-frequency power.

[0086] Furthermore, in step (b), before the step of supplying pulse waves, there is a step of supplying a continuous wave of high-frequency power from the high-frequency power supply 85, and the output value of the high-frequency power in the step of supplying pulse waves is greater than the output value of the high-frequency power in the step of supplying continuous waves. In this way, by igniting the plasma with a continuous wave of high-frequency power and then supplying pulse waves, the plasma processing method can generate plasma well while significantly reducing the number of particles.

[0087] Furthermore, the output value of the high-frequency power in the step of supplying pulsed waves is 1.5 times or more the output value of the high-frequency power in the step of supplying continuous waves. As a result, the plasma processing method can suppress damage to the quartz part (housing 90) in the step of supplying continuous waves, and can perform plasma processing efficiently in the step of supplying pulsed waves.

[0088] Furthermore, in steps (a) and (b), a rotary table 2 on which multiple substrates (wafers W) are placed, located inside the processing container 1, is rotated. This allows the plasma processing method to perform stable plasma processing on each substrate while reducing the number of particles, even when depositing nitride films on multiple substrates while rotating them.

[0089] A second aspect of this disclosure is a substrate processing apparatus 100 for depositing a nitride film on a substrate (wafer W) using plasma, comprising: a processing container 1 for housing the substrate; processing gas nozzles (third processing gas nozzles 33-35) for supplying a plasma processing gas containing nitrogen gas to a plasma processing space 99 inside the processing container 1; a plasma source unit 80 capable of generating plasma in the plasma processing space 99, with an antenna 83 positioned on a quartz part (housing 90) exposed to the plasma processing space 99; and a high-frequency power supply 85 for supplying high-frequency power to the antenna 83 when the plasma processing gas is supplied from the processing gas nozzles to the plasma processing space 99, wherein the high-frequency power supply 85 supplies pulse waves that repeatedly switch on and off as high-frequency power to the antenna 83, thereby lowering the average electron density and the average electron temperature relative to the average electron density of the plasma. Even in this case, the substrate processing apparatus 100 can suppress nitrogen reactive species when generating plasma and depositing a nitride film.

[0090] The plasma processing methods according to the embodiments disclosed herein are illustrative and not restrictive in all respects. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be otherwise configured and combined in a non-consistent manner.

[0091] The plasma processing method disclosed herein is applicable not only to ICP but also to other devices such as Capacitively Coupled Plasma (CCP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP). [Explanation of symbols]

[0092] 1. Processing container 83 Antenna 85 High frequency power supply 90 cabinets 99 Plasma Processing Space 100 Substrate Processing Equipment W wafer

Claims

1. A plasma processing method for depositing a nitride film on a substrate using plasma, (a) A step of supplying a plasma treatment gas containing nitrogen gas to the plasma treatment space inside the treatment vessel, During the execution of step (a) above, the process includes (b) supplying high-frequency power from a high-frequency power supply to an antenna placed on a quartz portion exposed to the plasma processing space in order to generate the plasma in the plasma processing space, In step (b) above, the average electron temperature of the plasma is reduced relative to the average electron density by supplying the antenna with a pulse wave that repeatedly switches on and off as the high-frequency power. Furthermore, step (b) includes a step of supplying a continuous wave of the high-frequency power from the high-frequency power supply to the antenna before the step of supplying the pulse wave, The output value of the high-frequency power in the step of supplying the pulse wave is greater than the output value of the high-frequency power in the step of supplying the continuous wave. Plasma treatment method.

2. In step (b) above, the duty cycle of the pulse wave is set to a range of 66.7% to 99.9%. The plasma treatment method according to claim 1.

3. In step (b) above, the high-frequency power is supplied with an output value in the range of 500W to 5000W. The plasma treatment method according to claim 1.

4. The output value of the high-frequency power in the step of supplying the pulse wave is 1.5 times or more the output value of the high-frequency power in the step of supplying the continuous wave. A plasma treatment method according to any one of claims 1 to 3.

5. In steps (a) and (b) above, a rotary table on which multiple substrates are placed is rotated inside the processing container. A plasma treatment method according to any one of claims 1 to 3.

6. A substrate processing apparatus for depositing a nitride film on a substrate using plasma, A processing container for housing the aforementioned substrate, A processing gas nozzle that supplies a plasma processing gas containing nitrogen gas to the plasma processing space inside the processing container, An antenna is placed on the quartz portion exposed to the plasma processing space, and a plasma source capable of generating the plasma is placed in the plasma processing space. When the plasma processing gas is supplied from the processing gas nozzle to the plasma processing space, a high-frequency power supply is provided to supply high-frequency power to the antenna, It comprises a control unit and, The control unit controls the high-frequency power supply and supplies the antenna with pulse waves that repeatedly switch on and off as high-frequency power, thereby lowering the average electron temperature relative to the average electron density of the plasma. Furthermore, the control unit performs the step of supplying a continuous wave of the high-frequency power from the high-frequency power supply to the antenna before the step of supplying the pulse wave. The output value of the high-frequency power in the step of supplying the pulse wave is made greater than the output value of the high-frequency power in the step of supplying the continuous wave. Circuit board processing equipment.

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