Plasma processing apparatus and film forming method

Abstract

To increase plasma density.SOLUTION: A plasma processing apparatus for depositing a film on a substrate comprises: a reaction tube provided in a processing vessel; a boat holding the substrate and carried in and out of the reaction tube; a plasma generator unit connected to the reaction tube and generating plasma from a gas; a gas supply unit supplying the gas to the plasma generator unit; an electrode installation unit installed across the plasma generator unit and having electrodes; an RF power supply connected to the electrodes and supplying RF to the electrodes; a coil installed in the electrode installation unit and separated from the electrodes; and a DC power supply connected to the coil and supplying DC current to the coil.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a plasma processing apparatus and a film forming method. [Background technology]

[0002] During the film formation process, a desired film adheres to and accumulates on the inner walls of the plasma processing apparatus, etc. When the cumulative thickness of the desired film exceeds a predetermined threshold, the film peels off, and the amount of particles generated on the substrate increases in proportion to the cumulative thickness.

[0003] The film deposited on the inner wall of the plasma processing apparatus is removed by dry cleaning when the cumulative film thickness reaches a predetermined value so that the amount of particles generated on the substrate does not exceed a control value. To increase productivity, it is desirable to make the period between one dry cleaning and the next, i.e., the dry cleaning cycle, as long as possible.

[0004] Many particles generated on a substrate are generated from the plasma generation unit. As one method for reducing particles generated on a substrate, for example, Patent Document 1 proposes a method for controlling the stress generated in a deposited film. However, there is a concern that including this film stress control process in the film deposition process may reduce productivity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4607637 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides techniques for increasing plasma density. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, there is provided a plasma processing apparatus for forming a film on a substrate, the plasma processing apparatus comprising: a reaction tube disposed within a processing vessel; a boat for holding a substrate and being loaded into and unloaded from the reaction tube; a plasma generating unit communicating with the reaction tube and generating plasma from a gas; a gas supply unit for supplying the gas to the plasma generating unit; electrode installation units disposed on either side of the plasma generating unit and having an electrode; an RF power supply connected to the electrode and supplying a high frequency to the electrode; a coil disposed within the electrode installation unit and spaced apart from the electrode; and a DC power supply connected to the coil and supplying a DC current to the coil. The electrodes are disposed facing each other inside the electrode mounting portion, and one or more coils are disposed alongside the facing electrodes. SUMMARY OF THE INVENTION A plasma processing apparatus is provided. [Effects of the Invention]

[0008] According to one aspect, the plasma density can be increased. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view illustrating an example of a heat treatment apparatus according to an embodiment. [Figure 2] 4 is a cross-sectional view (cross-section BB in FIG. 3) showing an example of an electrode placement portion according to the embodiment. FIG. [Figure 3] FIG. 2 is a cross-sectional view of FIG. 1 taken along line AA. [Figure 4] FIG. 2 is a schematic three-dimensional view of a coil according to an embodiment. [Figure 5] 10 is a diagram showing the expected generation of a magnetic field generated by a coil according to an embodiment. [Figure 6] FIG. 10 is a schematic cross-sectional view showing another example of the electrode placement portion according to the embodiment. [Figure 7] 1 is a flowchart showing an example of a film forming method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0011] [Heat treatment equipment] A heat treatment apparatus having a plasma generating unit will be described as an example of a plasma treatment apparatus according to an embodiment with reference to Fig. 1. Fig. 1 is a schematic view showing an example of a heat treatment apparatus according to an embodiment.

[0012] The heat treatment apparatus 1 has a processing vessel 10 and a reaction tube 3. The processing vessel 10 has a substantially cylindrical shape. The reaction tube 3 is disposed inside the processing vessel 10. The reaction tube 3 has a substantially cylindrical shape with a ceiling. The reaction tube 3 is made of a heat-resistant material such as quartz. The reaction tube 3 accommodates a substrate. The heat treatment apparatus 1 has a double structure consisting of the reaction tube 3 and the processing vessel 10.

[0013] The heat treatment apparatus 1 includes a manifold 13, injectors 14 and 15, a cover 16, a gas outlet 19, etc. The manifold 13 has a substantially cylindrical shape. The manifold 13 supports the lower end of the reaction tube 3. The manifold 13 is made of, for example, stainless steel.

[0014] A boat 18 carrying a large number of substrates W (e.g., 25 to 150 substrates) stacked in multiple stages is inserted (loaded) into the reaction tube 3 from below the manifold 13. In this manner, during film formation, the large number of substrates W are accommodated substantially horizontally in the reaction tube 3 with vertical spacing between them. The boat 18 is made of, for example, quartz. The boat 18 has three rods 6 (only two are shown in FIG. 1 ), and grooves (not shown) formed in the rods 6 support the large number of substrates W. The substrates W may be, for example, semiconductor wafers. After the boat 18 is loaded into the reaction tube 3 and a desired film is formed on the substrates W, the boat 18 is unloaded from the reaction tube 3.

[0015] The boat 18 is placed on the table 5 via a heat-insulating tube 17 made of quartz. The table 5 is supported on a rotary shaft 7 that passes through a metal (stainless steel) cover 16 that opens and closes the opening at the bottom end of the manifold 13.

[0016] A magnetic fluid seal is provided at the penetration portion of the rotating shaft 7, which airtightly seals and rotatably supports the rotating shaft 7. A seal member 8 is provided between the periphery of the lid 16 and the lower end of the manifold 13 to maintain airtightness inside the processing vessel 10.

[0017] The rotation shaft 7 is attached to the tip of an arm 2 supported by a lifting mechanism (not shown), such as a boat elevator, and the boat 18 and the lid 16 are raised and lowered as a unit to be inserted into and removed from the processing vessel 10. Note that the table 5 may be fixed to the lid 16 side, so that the substrates W can be processed without rotating the boat 18.

[0018] The heat treatment apparatus 1 includes a gas supply unit 20 that supplies predetermined gases, such as a process gas and a purge gas, into the processing chamber 10. The gas supply unit 20 includes injectors 14 and 15, which are gas supply pipes. The injectors 14 and 15 are made of, for example, quartz, and extend vertically, penetrating the sidewall of the manifold 13. A plurality of gas holes 14a and 15a are formed at predetermined intervals in the vertical portion of the injectors 14 and 15, respectively, over a length corresponding to the substrate support range of the boat 18. Each gas hole 14a and 15a discharges gas horizontally. The injectors 14 and 15 are made of, for example, quartz, and are quartz tubes that penetrate the sidewall of the manifold 13. While the example in FIG. 1 shows a single injector 14 and 15, multiple injectors 14 and 15 may be used.

[0019] A silicon-containing gas for film formation is supplied to the injector 14 from a source gas supply source 21 via a gas pipe. In this embodiment, an example in which dichlorosilane (SiH2Cl2) is supplied will be described, but the silicon-containing gas is not limited to this. A flow rate controller 22 and an on-off valve V0 are provided in the gas pipe. Dichlorosilane is output from the source gas supply source 21, and its flow rate is controlled by the flow rate controller 22. The supply of dichlorosilane into the reaction tube 3 is turned on and off by opening and closing the on-off valve V0.

[0020] The vertical portion of the injector 15 is provided within the plasma generation unit 60. Ammonia (NH3) gas is supplied to the injector 15 from an ammonia gas supply source 23 via a gas pipe. The gas pipe is provided with a flow rate controller 25 and an on-off valve V1. NH3 gas is output from the ammonia gas supply source 23, and its flow rate is controlled by the flow rate controller 25. The on-off valve V1 opens and closes to turn on or off the supply of NH3 gas into the plasma generation unit 60. The NH3 gas is converted into plasma in the plasma generation unit 60 and supplied into the reaction tube 3. Hydrogen (H2) gas is also supplied to the injector 15 from a hydrogen gas supply source 24 via a gas pipe. The gas pipe is provided with a flow rate controller 25 and an on-off valve V2. H2 gas is output from the hydrogen gas supply source 24, and its flow rate is controlled by the flow rate controller 25. The on-off valve V2 opens and closes to turn on or off the supply of H2 gas into the plasma generation unit 60. The H2 gas is converted into plasma in the plasma generation unit 60 and supplied into the reaction tube 3.

[0021] Although not shown, an injector may be provided to supply purge gas from a purge gas supply source via a gas pipe. The gas pipe is provided with a flow rate controller and an on-off valve. Thus, the purge gas is supplied from the purge gas supply source to the reaction tube 3 via the gas pipe at a predetermined flow rate. Examples of the purge gas include inert gases such as nitrogen (N2) and argon (Ar). The purge gas may be supplied from at least one of the injectors 14 and 15. In this embodiment, the purge gas is supplied from the injectors 14 and 15. With this configuration, the gas supply unit 20 supplies ammonia gas, hydrogen gas, and purge gas to the plasma generation unit 60. The gas supply unit 20 also supplies dichlorosilane and purge gas to the reaction tube 3. The process gas includes, for example, a film formation gas, a cleaning gas, and a purge gas. In this embodiment, the film formation gas is a gas used to form a silicon nitride (SiN) film and includes a silicon-containing gas such as dichlorosilane, ammonia gas, and hydrogen gas.

[0022] The heat treatment apparatus 1 further includes an exhaust unit 30, a heating unit 40, a cooling unit 50, a control device 90, etc. The process gas supplied into the process chamber 10 is exhausted by the exhaust unit 30 through a gas outlet 19. The gas outlet 19 is formed in the manifold 13. The exhaust unit 30 includes an exhaust device 31, an exhaust pipe 32, and a pressure controller 33. The exhaust device 31 is, for example, a vacuum pump such as a dry pump or a turbomolecular pump. The exhaust pipe 32 connects the gas outlet 19, the pressure controller 33, and the exhaust device 31. The pressure controller 33 is installed in the exhaust pipe 32 and controls the pressure inside the process chamber 10 by adjusting the conductance of the exhaust pipe 32. The pressure controller 33 is, for example, an automatic pressure control valve.

[0023] The heating unit 40 includes a heat insulating material 41, a heater 42, and an outer skin 43. The heat insulating material 41 has a substantially cylindrical shape and is provided around the outer tube 12. The heat insulating material 41 is formed mainly of silica and alumina. The heater 42 is an example of a heating element and is provided on the inner periphery of the heat insulating material 41. The heater 42 is provided in a linear or planar shape on the side wall of the processing vessel 10 so that the temperature can be controlled in multiple zones in the height direction of the processing vessel 10. The outer skin 43 is provided to cover the outer periphery of the heat insulating material 41. The outer skin 43 maintains the shape of the heat insulating material 41 and reinforces it. The outer skin 43 is made of a metal such as stainless steel. In addition, a water-cooled jacket (not shown) may be provided around the outer periphery of the outer skin 43 to suppress thermal influence of the heating unit 40 on the outside. In the heating unit 40, the amount of heat generated by the heater 42 is determined by the power supplied to the heater 42, and the inside of the processing chamber 10 is thereby heated to a desired temperature.

[0024] The cooling unit 50 supplies a cooling fluid toward the processing vessel 10 to cool the wafer W in the processing vessel 10. The cooling fluid may be, for example, air. The cooling unit 50 supplies the cooling fluid toward the processing vessel 10 when, for example, rapidly lowering the temperature of the wafer W after heat treatment. The cooling unit 50 has a fluid flow path 51, an outlet 52, a distribution flow path 53, a flow rate adjustment unit 54, and a heat exhaust port 55.

[0025] A plurality of fluid flow paths 51 are formed in the height direction between the thermal insulation material 41 and the outer skin 43. The fluid flow paths 51 are, for example, flow paths formed along the circumferential direction on the outside of the thermal insulation material 41. Blowing holes 52 are formed from each fluid flow path 51 to penetrate the thermal insulation material 41, and blow out the cooling fluid into the space between the outer pipe 12 and the thermal insulation material 41.

[0026] The distribution flow path 53 is provided outside the outer skin 43, and distributes and supplies the cooling fluid to each fluid flow path 51. The flow rate adjustment unit 54 is interposed in the distribution flow path 53, and adjusts the flow rate of the cooling fluid supplied to the fluid flow path 51.

[0027] The heat exhaust port 55 is provided above the plurality of outlet holes 52, and exhausts the cooling fluid supplied to the space between the outer pipe 12 and the heat insulating material 41 to the outside of the heat treatment device 1. The cooling fluid exhausted to the outside of the heat treatment device 1 is cooled, for example, by a heat exchanger, and then supplied again to the distribution flow path 53. However, the cooling fluid exhausted to the outside of the heat treatment device 1 may be exhausted without being reused.

[0028] The control device 90 controls the operation of the heat treatment device 1. The control device 90 may be, for example, a computer. A computer program that controls the overall operation of the heat treatment device 1 is stored in a storage medium. The storage medium may be, for example, a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like.

[0029] [Plasma generation unit and electrode installation unit] A plasma generating unit 60 is formed on a part of the sidewall of the reaction tube 3. The plasma generating unit 60 is in communication with the reaction tube 3 via an opening 81 provided in the reaction tube 3. An example of the configuration of the plasma generating unit 60 and the electrode installation unit will be described with reference to Figs. 2 and 3 in addition to Fig. 1. Fig. 2 is a cross-sectional schematic diagram showing an example of the electrode installation unit 70 according to the embodiment, and shows the BB cross section of Fig. 3, the matching circuit 27, the RF power supply 28, and the DC power supply 63. Fig. 3 is a diagram showing the AA cross section of Fig. 1.

[0030] 1 to 3, the plasma generating unit 60 is provided on a part of the side wall of the reaction tube 3 along the longitudinal direction (vertical direction) of the reaction tube 3, and generates plasma from gas. Referring to FIG. 3, the plasma generating unit 60 has a plasma compartment wall 60a (see FIG. 4) that protrudes in a rectangular shape from the reaction tube 3 along the longitudinal direction of the reaction tube 3. The plasma compartment wall 60a is welded to the reaction tube 3, and the internal space of the plasma generating unit 60 communicates with the reaction tube 3 via an opening 81 (see FIGS. 1 and 3).

[0031] 3, an injector 14 for supplying a silicon precursor (e.g., dichlorosilane SiH2Cl2) is installed in the reaction tube 3. A raw material gas supply source 21 of a gas supply unit 20 supplies dichlorosilane gas into the reaction tube 3 from multiple gas holes 14a formed in the vertical direction.

[0032] An injector 15 for supplying NH3 gas and H2 gas is installed inside the plasma generating unit 60. An ammonia gas supply source 23 of the gas supply unit 20 supplies NH3 gas into the plasma generating unit 60 from multiple gas holes 15a formed in the vertical direction, and a hydrogen gas supply source 24 supplies H2 gas into the plasma generating unit 60 from multiple gas holes 15a formed in the vertical direction.

[0033] An exhaust port 19 (see FIGS. 1 and 3) for evacuating the inside of the reaction tube 3 is provided at the lower part of the side wall of the reaction tube 3 opposite the opening 81, and exhausts the gases supplied from the injectors 14 and 15.

[0034] 3, the electrode installation unit 70 is installed so as to sandwich the plasma generation unit 60, and has the high-frequency electrode 26 and coils 61, 62 inside. The electrode installation unit 70 is installed adjacent to the opposing plasma partition walls 60a1, 60a2 of the plasma partition walls 60a of the plasma generation unit 60. The pair of high-frequency electrodes 26 are installed on both side walls 60a1, 60a2 of the plasma generation unit 60 so as to sandwich the plasma generation unit 60. The plasma generation unit 60 is a vacuum space, and the electrode installation unit 70 is an atmospheric space.

[0035] 2 shows the high-frequency electrode 26 and coils 61, 62 provided in one electrode installation section 70 of the plasma generation section 60. As shown in FIG. 2, the high-frequency electrode 26 extends in the longitudinal direction along one of the opposing plasma compartment walls 60a1, 60a2 (hereinafter also referred to as walls 60a1, 60a2). The high-frequency electrode 26 forms a pair with the high-frequency electrode 26 that extends in the longitudinal direction along the other of the walls 60a1, 60a2 in the other electrode installation section 70. The coils 61, 62 are wound along the walls 60a1, 60a2 (see FIG. 4).

[0036] The pair of high-frequency electrodes 26 are connected to an RF power supply 28 via a matching circuit 27, and are supplied with radio frequency (RF) from the RF power supply 28. The plasma generating unit 60 uses the radio frequency power to convert NH gas into plasma and generate active species for nitriding a film within the plasma generating unit 60. The plasma generating unit 60 also uses the radio frequency power to convert H gas into plasma and generate hydrogen (H) radicals within the plasma generating unit 60.

[0037] The coils 61 and 62 are provided at a distance from the high-frequency electrode 26. As shown in Fig. 2, the coils 61 and 62 are connected to a DC power supply 63. The DC power supply 63 supplies a DC current to the coils 61 and 62.

[0038] As shown in FIG. 3, an insulating member 36 such as quartz is embedded in the electrode installation section 70 to electrically insulate the pair of high-frequency electrodes 26 and coils 61 and 62 provided along the opposing walls 60a1 and 60a2 of the plasma partition wall 60a.

[0039] The coils 61 and 62 are wound one or more times along the opposing walls 60a1 and 60a2. FIG. 4 is a three-dimensional schematic diagram of the coils 61 and 62 for applying a magnetic field. The two coils 61 and 62 are wound on the outside of the plasma generation unit 60. The coil 61 is the one farther from the reaction tube 3, and the coil 62 is the one closer to the reaction tube 3. As shown in FIG. 4, the coils 61 and 62 are connected below the plasma generation unit 60 to form an integrated coil. A DC power supply 63 is connected to these coils, and a DC current is supplied from the DC power supply 63. A high frequency is also applied to the high frequency electrode 26 from the RF power supply 28. This applies a magnetic field inside the plasma generation unit 60, which generates plasma. The coils 61 and 62 may be separated and connected to their own dedicated DC power supplies. Although FIG. 4 shows the coils 61 and 62 wound one turn along the walls 60a1 and 60a2, the coils 61 and 62 may be wound multiple turns.

[0040] FIG. 5 shows a predicted diagram of the magnetic field generated by coils 61 and 62 according to the embodiment. Increasing the plasma density in the plasma generating unit 60 and increasing the amount of reactive species generated can shorten the time required for the plasma processing step during film formation. Therefore, in this embodiment, in order to increase the plasma density and increase the amount of reactive species generated, coils 61 and 62 are installed near the high-frequency electrode 26 (parallel plate electrode). A direct current is then passed through the coils 61 and 62 to generate a magnetic field. The generated magnetic field is then applied to plasma generated from NH3 gas and H2 gas by high-frequency waves.

[0041] The magnetic field formed by the two coils 61, 62 has a direction and range indicated by the arrows in FIG. 5. In the example of FIGS. 4 and 5, a direct current flows from bottom to top through the front coils 61, 62, flows toward the back at the top, and flows from top to bottom through the back coils 61, 62. This generates the magnetic field shown in FIG. 5. However, the direction of the direct current may be reversed. Electrons in the plasma P undergo circular motion (cyclotron motion) under the influence of the magnetic field. This increases the number of times electrons collide with neutral particles in the plasma P (collision frequency). As a result, even when the same power of radio frequency is supplied to the radio frequency electrode 26, in this embodiment where a magnetic field is formed, the density of the plasma P can be increased compared to when a magnetic field is not formed.

[0042] Points a, b, and c shown in Figure 5 are located in the center of the plasma generation unit 60 (at approximately the same distance from the walls 60a1 and 60a2). Point a is located closer to the injector 15 than the region directly below the high-frequency electrode 26, midway along the line connecting the front and back coils 61 shown in Figure 5, and is affected by the magnetic field generated by the coil 61. Point b is located closer to the reaction tube 3 than the region directly below the high-frequency electrode 26, midway along the line connecting the front and back coils 62, and is affected by the magnetic field generated by the coil 62. Point c is located in the region directly below the high-frequency electrode 26, i.e., in the center between the high-frequency electrodes 26, and a combined magnetic field generated by the coils 61 and 62 is generated from the substrate W side toward the injector 15 side. The magnetic field at point c is weaker than the magnetic fields at points a and b, and is a region where the effect of magnetic field application is small.

[0043] Coils 61 and 62, or only coil 62, are installed, and a magnetic field generated by passing a direct current through the coils is applied to the plasma to increase the plasma density. Each coil has approximately 1 to 10 turns. The direct current supplied to the coils is approximately 1 A to 10 A. Only one of coils 61 and 62 may be installed. However, if either coil 61 or 62 is installed, it is preferable to install coil 62, which is closer to substrate W, than coil 61, which is farther from substrate W.

[0044] The coils 61 and 62 are made of a metal material with high heat resistance and high conductivity because they are installed inside the processing vessel 10 in which the heater 42 is disposed. By using a material with high conductivity, a strong magnetic field can be generated.

[0045] An electron (mass m) in a magnetic field with magnetic flux density B e , charge e) moves at a constant angular velocity (angular frequency) ω in a plane perpendicular to the magnetic field. c =eB / m e It performs a cyclotron motion with ω c is called the cyclotron frequency, and electromagnetic waves with an angular frequency equal to this frequency are resonantly absorbed. This phenomenon is called electron cyclotron resonance (ECR).

[0046] cyclotron frequency ω c When is equal to the radio frequency ω, the electron velocity is directly proportional to time, and the electrons accelerate with time. Since the electrons continue to absorb energy from the electric field created by the radio frequency electrode, this condition is electron cyclotron resonance.

[0047] For example, when the frequency of the high frequency power for generating plasma output from the RF power supply 28 is 13.56 MHz, the cyclotron frequency of the electrons in the plasma at point b is ω c [rad / s]. ω c / 2π=f c [s -1 The magnetic flux density at point b is 0.48 mT when [MHz] coincides with 13.56 MHz, which is the frequency of RF power supply 28. To achieve a magnetic flux density of 0.48 mT at point b by installing only coil 62, coil 62 must be wound five times and a current of about 5 A must be passed through it.

[0048] The current flowing through the coils 61 and 62 can be set arbitrarily within the range of 0 A to 10 A by the control device 90, so that an optimum magnetic field can be applied in accordance with the plasma generation conditions. The magnitude of the current flowing through the coils 61 and 62 can be set as one of the process parameters that can be set in the film formation recipe used in the film formation method of this embodiment.

[0049] One or more coils, up to two in number, may be installed inside the electrode installation unit 70. However, this is not limiting, and the coils may be attached to the outside of the plasma generation unit 60 along the wall 60a3 of the plasma compartment wall 60a where the injector 15 is installed. Fig. 6 shows an example in which a coil 64 is formed outside the plasma generation unit 60 along the wall 60a3. In this case, three coils, 61, 62, and 64, may be installed, or at least one of the coils 61, 62, and 64 may be installed.

[0050] In addition, in this embodiment, as shown in Figure 4, single-turn coils 61 and 62 are arranged side by side, but this is not limited to this. Each of coils 61 and 62 may be divided into two, upper and lower, and the upper coils 61 and 62 may be provided separately from the lower coils 61 and 62.

[0051] It is preferable that the plasma density be highest at the position facing the RF power supply 28 in the center of the plasma generating unit 60. Therefore, as shown in Fig. 6, recesses may be provided on both sides of the high-frequency electrode 26 in the walls 60a1 and 60a2 of the plasma generating unit 60, and coils 61 and 62 may be placed in the recesses. This allows the coils 61 and 62 to be placed closer to the position facing the RF power supply 28 in the center of the plasma generating unit 60. This creates a strong magnetic field near the center of the plasma generating unit 60, further increasing the plasma density.

[0052] [Film forming method] A method for depositing a film by loading a substrate W into the heat treatment apparatus 1, which is a batch-type plasma treatment apparatus described above, will now be described. In this embodiment, a film deposition process for depositing a silicon nitride film (hereinafter referred to as "SiN film") by ALD (Atomic Layer Deposition) is performed. However, the film deposition method is not limited to ALD. For example, film deposition by CVD may also be used.

[0053] If the cumulative thickness of the SiN film deposited on the inner wall or the like of the processing vessel 10 of the heat treatment apparatus 1 during the film formation process exceeds a preset threshold, the SiN film peels off, and the amount of particles generated on the substrate increases in proportion to the cumulative thickness. For example, when the temperature inside the reaction tube 3 is maintained at 500°C to 600°C and a SiN film is formed by the ALD method using plasma, the cumulative thickness of the film may exceed the control value for the amount of particle increase when the cumulative thickness is around 1.0 μm.

[0054] The SiN film formed on the inner wall of the processing vessel 10 of the heat treatment apparatus 1 is removed by dry cleaning when a predetermined cumulative film thickness is reached so that the amount of particles generated on the substrate does not exceed a control value. The SiN film formation process using the ALD method is then repeated until the predetermined cumulative film thickness is reached again. The period between dry cleanings of the processing vessel 10 is called the "dry cleaning cycle," and its length is usually expressed in cumulative film thickness (μm). In recent years, extending the dry cleaning cycle has become an important issue for improving the operating rate of the heat treatment apparatus 1.

[0055] When a SiN film is formed by the ALD method in the heat treatment apparatus 1, particles generated on the substrate are mostly generated from the plasma generating unit 60 installed near the substrate. It is thought that the SiN film formed in the plasma generating unit 60 is partially peeled off by the action of the plasma and adheres to the surface of the substrate W as minute particles.

[0056] There are several methods for reducing particles generated on the substrate W, but one effective method is to control the stress generated in the SiN film being deposited. In this case, to control the stress generated in the SiN film, a hydrogen radical purge step (HRP) is added to the ALD sequence (ALD cycle).

[0057] However, adding the HRP process increases the ALD cycle time, which causes a problem of reduced productivity. Therefore, in order to achieve both productivity and film stress control, in other words, to maintain and improve the effect of HRP while shortening the ALD cycle time, film formation is performed using a heat treatment apparatus 1 that can increase the plasma density and increase the amount of generated reactive species required.

[0058] The ALD cycle for a SiN film using the heat treatment device 1 repeats steps (1) to (5) in the following order: (1) nitridation using ammonia gas plasma using plasma assistance, (2) vacuum purging, (3) silicon precursor flow, (4) vacuum purging, and (5) HRP. An example of the silicon precursor flow in (3) is flowing dichlorosilane gas into the reaction tube 3 to cause a thermal reaction. No plasma is used in step (3).

[0059] To improve productivity, it is effective to shorten the time required for the plasma-using processes (1) and (5). To achieve this, the plasma density in the plasma generating unit 60 is increased to increase the amount of reactive species generated. It is known that simply increasing the applied high-frequency power to increase the amount of reactive species generated proportionally increases the amount of particles generated. Therefore, in the heat treatment apparatus 1 according to this embodiment, the goal of improving productivity is achieved not by increasing the high-frequency power, but by applying a DC magnetic field to the generated capacitively coupled plasma P. The film formation method according to this embodiment will now be described with reference to FIG. 7. FIG. 7 is a flowchart illustrating an example of the film formation method according to this embodiment. The film formation method of FIG. 7 is controlled by a control device 90.

[0060] When this process is started, the control device 90 supplies a direct current to the coils 61 and 62 to generate a magnetic field in the plasma generation unit 60. Also, NH3 gas is supplied from the injector 15, and high-frequency power is applied to the high-frequency electrode 26. This causes the high-frequency power to generate plasma from the NH3 gas. This causes the substrate W in the reaction tube 3 to be exposed to the plasma of the NH3 gas sent from the plasma generation unit 60, thereby executing a nitriding step (step S1) to nitride the film on the substrate W. The nitrogen-containing gas is not limited to NH3 gas, but may be N2 gas or the like.

[0061] Next, the control device 90 supplies an inert gas such as Ar gas from the injectors 14 and 15, and evacuates the reaction tube 3 using the exhaust device 31, thereby performing a vacuum purging step (step S3).

[0062] Next, the control device 90 causes SiH2Cl2 gas to flow from the injector 14 into the reaction tube 3 to cause a thermal reaction (step S5). Plasma is not used at this time. This exposes the substrate W to a film-forming gas containing silicon, forming a SiN film. Next, the control device 90 supplies an inert gas such as Ar gas from the injectors 14 and 15, evacuates the reaction tube 3 using the exhaust device 31, and performs a vacuum purge step (step S7).

[0063] Next, the control device 90 supplies a direct current to the coils 61 and 62 to generate a magnetic field in the plasma generation unit 60. It also supplies H2 gas from the injector 15 and applies high-frequency power to the high-frequency electrode 26. This generates plasma from the H2 gas using the high-frequency power, and the substrate W is exposed to the generated H2 gas plasma (step S9). This executes a hydrogen radical purge (HRP) process. This controls the stress generated in the deposited SiN film. As a result, the stress in the film can be controlled to reduce particles generated on the substrate W.

[0064] Next, the control device 90 supplies an inert gas such as Ar gas from the injectors 14 and 15, evacuates the reaction tube 3 using the exhaust device 31, and performs a vacuum purging step (step S11). Note that step S11 may be omitted.

[0065] Next, the control device 90 determines whether the process has been repeated a predetermined number of times (step S13). If the control device 90 determines that the process has not been repeated the predetermined number of times, the process returns to step S1 and repeats steps S1 to S11 in this order. If the control device 90 determines that the process has been repeated the predetermined number of times in step S13, the process ends.

[0066] According to the film forming method of this embodiment, plasma is generated in steps S1 and S9. At this time, high-frequency power is supplied to the high-frequency electrode 26 provided on the electrode installation unit 70 arranged along the plasma generation unit 60, and direct current is supplied to the coils 61 and 62 provided on the electrode installation unit 70.

[0067] This allows the time for step S1 (nitridation time) to be reduced by approximately 10 to 20% and the time for step S9 (HRP time) to be reduced by approximately 10 to 30% while maintaining film formation performance. Film formation performance refers to film quality, film thickness uniformity, and ALD cycle rate (the thickness of the film formed in one cycle of steps S1 to S11).

[0068] In this embodiment, a heat treatment device 1 equipped with coils 61 and 62 is used. This allows the dry cleaning cycle time to be extended by approximately 1.5 times compared to a heat treatment device not equipped with coils 61 and 62. As a result, the operating rate of the heat treatment device 1 can be increased. Furthermore, it is possible to reduce the man-hours and material costs for quality control.

[0069] As described above, the plasma processing apparatus and film formation method of this embodiment can increase the density of the plasma generated in the plasma generation unit 60. Furthermore, the productivity can be improved while suppressing particle generation in the film formation method. For example, the nitridation time using NH3 gas plasma and the HRP time using H2 gas plasma can be shortened within the time range of the film formation recipe (ALD cycle time) used in the ALD film formation method of this embodiment. This improves productivity while optimizing the stress generated in the SiN film to be formed, thereby suppressing particle generation. This allows the dry cleaning cycle to be extended by approximately 1.5 times compared to the current system.

[0070] The plasma processing apparatus and film forming method according to the presently disclosed embodiments should be considered to be illustrative in all respects and not restrictive. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0071] This film formation method is not limited to the formation of SiN films, but can also be used when forming other films. Furthermore, for example, this film formation method can also be used for surface treatment of a desired film, and the surface condition of the film can be changed. For example, when a substrate W on which a silicon oxide film (SiO2) has been formed is carried into a plasma processing apparatus, NH3 gas plasma is generated, and the substrate W is subjected to plasma processing, the surface of the silicon oxide film is nitrided. According to the plasma processing apparatus of the embodiment, the density of the NH3 gas plasma can be increased, thereby shortening the surface treatment time. [Explanation of symbols]

[0072] 1. Heat treatment equipment 3 Reaction tube 10 Processing container 14, 15 Injectors 20 Gas supply unit 26 High-frequency electrodes 40 Heating section 42 Heater 50 Cooling section 60 Plasma generation unit 61,62 Coil 70 Electrode installation part 90 Control device

Claims

1. A plasma processing apparatus for forming a film on a substrate, a reaction tube provided in the processing vessel; a boat that holds a substrate and is carried into and out of the reaction tube; a plasma generating unit communicating with the reaction tube and generating plasma from a gas; a gas supply unit that supplies the gas to the plasma generating unit; an electrode installation unit having an electrode and installed so as to sandwich the plasma generation unit; an RF power supply connected to the electrode and supplying high frequency waves to the electrode; a coil provided in the electrode installation portion and spaced apart from the electrode; a DC power supply connected to the coil and supplying a DC current to the coil; and The electrodes are disposed opposite each other inside the electrode mounting portion, In the plasma processing apparatus, one or more of the coils are installed in parallel with the opposing electrodes.

2. A plasma processing apparatus for forming a film on a substrate, comprising: a reaction tube provided in the processing vessel; a boat that holds a substrate and is carried into and out of the reaction tube; a plasma generating unit communicating with the reaction tube and generating plasma from a gas; a gas supply unit that supplies the gas to the plasma generating unit; an electrode installation unit having an electrode and installed so as to sandwich the plasma generation unit; an RF power supply connected to the electrode and supplying a high frequency to the electrode; a coil provided in the electrode installation portion and spaced apart from the electrode; a DC power supply connected to the coil and supplying a DC current to the coil; and The electrodes are disposed opposite each other inside the electrode mounting portion, A plasma processing apparatus, wherein a plurality of the coils are installed on both sides of the opposing electrodes.

3. the plasma generating unit protrudes from the reaction tube in a rectangular shape, The electrode installation portion is provided along the plasma partition wall of the plasma generation portion protruding in a rectangular shape.

3. The plasma processing apparatus according to claim 1 or 2.

4. The coil is wound one or more times along the opposing plasma compartment walls of the plasma generation unit. The plasma processing apparatus according to claim 3 .

5. At least one of the coils is installed closer to the reaction tube than the electrode. The plasma processing apparatus according to any one of claims 1 to 4.

6. A method for forming a film on a substrate in the plasma processing apparatus according to any one of claims 1 to 5, (a) exposing a substrate to a plasma generated from a nitrogen-containing gas; (b) exposing the substrate to a deposition gas containing silicon; (c) exposing the substrate to a plasma formed from hydrogen gas; (d) repeating the steps (a) to (c) in this order; A film forming method, wherein when generating the plasma in the steps (a) and (c), high frequency is supplied to the electrode provided in the electrode installation section arranged along the plasma generation section, and direct current is supplied to the coil provided in the electrode installation section.

7. a step of purging the inside of the reaction tube between the step (a) and the step (b) and between the step (b) and the step (c), The film forming method according to claim 6.

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