Substrate processing method and substrate processing system

Abstract

To provide a substrate processing method and a substrate processing system capable of forming a sound, low-resistance Ru film using electroless plating.SOLUTION: A substrate processing method has the processes of forming a Ru film on a substrate by electroless plating, processing the substrate on which the Ru film is formed with a plasma of inert gas, and reducing the substrate after the processing with the plasma of inert gas.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] In Patent Document 1, in forming an embedded multilayer wiring, in a via formed in an insulating film provided on a wiring, from the bottom surface where the wiring is exposed, using the exposed wiring as a catalyst, a film containing Cu, Co, Ni, or Ru is formed by electroless plating.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a substrate processing method and a substrate processing system capable of forming a sound and low-resistance Ru film using electroless plating.

Means for Solving the Problems

[0005] A substrate processing method according to an aspect of the present disclosure includes a step of forming a Ru film by electroless plating on a substrate, a step of treating the substrate on which the Ru film is formed with plasma of an inert gas, and a step of reducing the substrate after the treatment with plasma of the inert gas.

Effects of the Invention

[0006] According to the present disclosure, a substrate processing method and a substrate processing system capable of forming a sound and low-resistance Ru film using electroless plating are provided.

Brief Description of the Drawings

[0007] [Figure 1] This is a schematic diagram showing the state of cracks that occur when a Ru film is deposited by electroless plating and then subjected to reducing annealing. [Figure 2] This is a flowchart of a substrate processing method according to one embodiment. [Figure 3] A cross-sectional view showing an example of the structure of a substrate using a substrate processing method according to one embodiment. [Figure 4] Figure 3 is a cross-sectional view showing a state in which a Ru film has been embedded in vias formed on the substrate by electroless plating. [Figure 5] This is a block diagram showing a substrate processing system for carrying out a substrate processing method according to one embodiment. [Figure 6] Figure 5 is a cross-sectional view showing an example of an electroless plating apparatus included in the substrate processing system. [Figure 7] Figure 5 is a cross-sectional view showing an example of an inert gas plasma processing apparatus included in a substrate processing system. [Figure 8] Figure 5 is a cross-sectional view showing an example of a reduction treatment apparatus included in the substrate processing system. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the attached drawings.

[0009] <Background> First, let me explain the background. Patent Document 1, mentioned above, describes forming a film containing Cu, Co, Ni, or Ru within a via by electroless plating. Among these, Ru is attracting attention as a next-generation wiring material. However, Ru is easily oxidized, and oxidation is observed on the film surface and within the film in the as-depo state. Furthermore, in the as-depo state, Ru is not sufficiently crystallized, and its grain size is minute, making it close to an amorphous state. For this reason, Ru films in the as-depo state have high resistance.

[0010] Therefore, it is conceivable to form a Ru film by electroless plating, and then subject the Ru film to a reduction treatment such as reductive annealing to decompose the Ru oxide and promote crystallization.

[0011] However, it was found that when a reduction treatment such as reductive annealing is applied to a Ru film in the as-depo state formed by electroless plating, cracks C occur along the grain boundaries of the Ru film, as shown in the schematic diagram in Figure 1. The main causes of the cracks are thought to be that Ru is easily oxidized, and oxides are formed between the Ru grains, so oxygen is removed during the reduction treatment, degrading the adhesion between the Ru grains, and volume shrinkage occurs due to the promotion of crystallization by the reduction treatment.

[0012] Therefore, in one embodiment, as a post-treatment after forming a Ru film by electroless plating, the substrate is treated with a plasma of an inert gas such as Ar gas or N2 gas, followed by a reduction treatment. When treating the substrate with a plasma of an inert gas, the physical action of the plasma of the inert gas can destroy the Ru grains and decompose the Ru oxide. As a result, deterioration of adhesion between grains does not occur, and cracks due to volume shrinkage when crystallization is promoted by the subsequent reduction treatment are suppressed, making it possible to form a sound Ru film with low resistance.

[0013] <Substrate Processing Method> Next, a substrate processing method according to one embodiment will be described in more detail. Figure 2 is a flowchart showing a substrate processing method according to one embodiment. The substrate processing method of this embodiment includes the steps of forming a Ru film on a substrate by electroless plating (step ST1), performing a plasma treatment of the substrate after the Ru film has been formed using an inert gas (step ST2), and performing a reduction treatment of the substrate after step ST2 (step ST3).

[0014] In step ST1, the substrate is not particularly limited, but a semiconductor substrate (semiconductor wafer) having a semiconductor substrate such as silicon can be used. For example, it may be a substrate having a structure as shown in FIG. 3. The substrate W in FIG. 3 has a structural portion 110 provided on a Si substrate (not shown). The structural portion 110 has a lower layer wiring 101 and an insulating film 102 formed on the lower layer wiring 101, and fine vias 103 are formed in the insulating film 102. The lower layer wiring 101 is exposed at the bottom surface of the via 103. The insulating film 102 has a lower nitride film 102a and an upper oxide film 102b. For the lower layer wiring 101, Cu or Ru can be preferably used. Alternatively, Ni or Co can also be used.

[0015] The electroless plating process in step ST1 is performed by applying a chemical solution (plating solution) for electroless plating on the substrate and then heating it. The heating temperature is 50~85 preferably [temperature value] °C. After heating, a drying process is performed on the substrate.

[0016] When the substrate has the structure shown in FIG. 3, as shown in FIG. 4, by performing an electroless plating process, a Ru film 105 is embedded in the via 103. At this time, with the lower layer wiring 101 exposed at the bottom surface of the via 103 as a catalyst, the Ru film 105 grows bottom-up from the bottom surface of the via 103.

[0017] The step of performing the treatment with the plasma of an inert gas in step ST2 exposes the substrate on which the Ru film is formed by electroless plating to the plasma of the inert gas, and the physical action of the plasma is exerted on the Ru film. Thereby, the Ru grains of the ruthenium oxide film can be destroyed, and the ruthenium oxide formed by oxidizing the Ru film can be decomposed.

[0018] The plasma treatment in step ST2 is performed in a vacuum atmosphere. The pressure may be in the range of 100 mTorr to 2 Torr (13.3 to 266.6 Pa). The substrate temperature may be in the range of 70 to 400°C, with 70 to 130°C and more preferably 100 to 130°C. Degassing tends to increase above 130°C. The processing time for step ST2 may be 5 to 300 seconds. As the inert gas, noble gases such as Ar gas and He gas, or N2 gas can be used. Among these, Ar gas and N2 gas are preferred, but Ar gas, which has a large number of atoms and strong physical activity, is particularly preferred. It may be 100% Ar gas, but it may also be a mixture of two or more inert gases, such as Ar gas + He gas, or Ar gas + N2 gas. The plasma in step ST2 is not particularly limited, and various plasmas such as capacitively coupled plasma, inductively coupled plasma, and microwave plasma can be used.

[0019] Furthermore, in step ST2, a bias may be applied to the substrate. By applying a bias to the substrate, ions in the plasma can be attracted to the substrate, increasing the physical effect on the Ru film on the substrate surface. In particular, a greater effect can be obtained by using Ar ions, which have a large number of atoms. The bias may be a high-frequency bias.

[0020] Step ST3, the process of reducing the substrate, is a process that reduces the oxidized parts of the Ru film and promotes the crystallization of the Ru film, thereby lowering the resistance of the Ru film.

[0021] The reduction treatment may be reduction annealing or hydrogen plasma treatment. Reduction annealing is a process in which the substrate is heated while supplying a reducing gas, and is performed at atmospheric pressure. Hydrogen plasma treatment is a process in which the substrate is treated with a plasma containing H2 gas, for example, H2 gas alone, or H2 gas + inert gas, and is performed under vacuum.

[0022] If the reduction treatment is reductive annealing, the substrate temperature may be 200 to 430°C, for example, 400°C. Examples of reducing gases include forming gas, H2 gas, formic acid, etc., and at least one of these can be suitably used. The forming gas is a mixture of H2 gas and N2 gas, and a mixture in which H2 gas is 5.7% or less of the explosion limit, for example, 4%, can be used. The time for reductive annealing depends on the thickness of the Ru film, but may be about 5 to 120 minutes. Reductive annealing is performed at atmospheric pressure, but it is preferable to use a sealed apparatus so that the gas composition can be maintained.

[0023] If the reduction treatment is performed using hydrogen plasma, the treatment is carried out in a vacuum atmosphere. The pressure may be in the range of 100 mTorr to 2 Torr (13.3 to 266.6 Pa). The substrate temperature may be in the range of 70 to 400°C, with a range of 70 to 130°C, and more preferably 100 to 130°C. The hydrogen plasma treatment can be performed using a plasma of H2 gas or H2 gas + inert gas. The plasma used is not particularly limited, and various plasmas such as capacitively coupled plasma, inductively coupled plasma, and microwave plasma can be used. When the reduction treatment is performed using hydrogen plasma, it may be carried out using the same apparatus as the inert gas plasma treatment in step ST2.

[0024] As described above, in this embodiment, by performing the reduction treatment in step ST3 after the plasma treatment with an inert gas in step ST2, the decrease in adhesion between grains due to oxygen desorption and the occurrence of cracks due to crystallization promotion during the reduction treatment are suppressed.

[0025] In other words, the plasma treatment with inert gas in step ST2 can destroy Ru grains and decompose Ru oxides, thereby suppressing the deterioration of adhesion between grains and preventing cracks caused by volume shrinkage during the subsequent reduction treatment.

[0026] The reaction model for the plasma treatment in step ST2 is presumed to be similar to the destruction and amorphous formation of Si crystals that occurs when impurities are doped into a Si substrate using implantation.

[0027] Thus, according to this embodiment, the Ru film formed by electroless plating can be reduced without causing cracks, and a sound, low-resistance Ru film can be formed.

[0028] Furthermore, when using a substrate with a structure in which fine vias 103 are formed as shown in Figure 3, and embedding a Ru film within the vias 103, void-free embedding is difficult with conventional CVD or PVD. However, by using electroless plating as in this embodiment, void-free embedding is possible. That is, in the case of electroless plating, Ru selectively grows from the underlying wiring 101 exposed on the bottom surface of the via 103, using the underlying wiring 101 as a catalyst, and is embedded by bottom-up growth, allowing for void-free embedding even in fine vias. In addition, the temperature during film formation is low, less than 100°C. Moreover, in this embodiment, as described above, a low-resistance Ru film can be obtained without generating cracks by electroless plating, thus effectively demonstrating the advantages of embedding Ru in such vias by electroless plating.

[0029] <Substrate Processing System> Next, we will describe a substrate processing system for implementing the above substrate processing method. Figure 5 is a block diagram showing a substrate processing system for carrying out a substrate processing method according to one embodiment.

[0030] The substrate processing system 200 includes an electroless plating apparatus 300, an inert gas plasma processing apparatus 400, and a reduction processing apparatus 500. Substrate transport between the electroless plating apparatus 300 and the inert gas plasma processing apparatus 400, and between the inert gas plasma processing apparatus 400 and the reduction processing apparatus 500, are performed by substrate transport mechanisms 600 and 700, respectively. The substrate processing system 200 also includes a control unit 800 for controlling the electroless plating apparatus 300, the inert gas plasma processing apparatus 400, the reduction processing apparatus 500, and the substrate transport mechanisms 600 and 700. These will be described individually below.

[0031] [Electroless plating equipment] Figure 6 is a cross-sectional view showing an example of an electroless plating apparatus 300. The electroless plating apparatus 300 forms a Ru film by electroless plating and, as shown in Figure 6, comprises a chamber 51, a substrate holding section 52, and a plating solution supply section 53. The substrate holding section 52 is located inside the chamber 51 and has a chuck member 521 that vacuum-adheres the lower surface (back surface) of the substrate W, holding the substrate W horizontally. The substrate holding section 52 may be a mechanical chuck. The plating solution supply section 53 supplies the plating solution L1 to the upper surface (processing surface) of the substrate W held by the substrate holding section 52.

[0032] A rotary motor 523 is connected to the substrate holder 52 via a rotary shaft 522. When the rotary motor 523 is driven, the substrate holder 52 rotates together with the substrate W. The rotary motor 523 is supported by a base 524 fixed to the chamber 51.

[0033] The plating solution supply unit 53 includes a plating solution nozzle 531 that discharges plating solution L1 onto a substrate W held by a substrate holding unit 52, and a plating solution supply source 532 that supplies the plating solution L1 to the plating solution nozzle 531. The plating solution supply source 532 supplies the plating solution L1, which is temperature-controlled to a predetermined temperature, to the plating solution nozzle 531. The plating solution nozzle 531 is held by a nozzle arm 56 and is configured to be movable.

[0034] The plating solution L1 is, for example, a plating solution for autocatalytic (reducing) electroless plating, and contains Ru ions and a reducing agent such as hypophosphorous acid, dimethylamine borane, or hydrazine. The plating solution L1 may also contain appropriate additives. By discharging the plating solution L1 from the plating solution nozzle 531, a Ru film is applied to the upper surface of the substrate W.

[0035] The electroless plating apparatus 300 further includes, as other processing liquid supply units, a cleaning liquid supply unit 54 that supplies cleaning liquid L2 to the upper surface of the substrate W held by the substrate holding unit 52, and a rinsing liquid supply unit 55 that supplies rinsing liquid L3 to the upper surface of the substrate W.

[0036] The cleaning solution supply unit 54 includes a cleaning solution nozzle 541 that discharges cleaning solution L2 onto a substrate W held by the substrate holding unit 52, and a cleaning solution supply source 542 that supplies cleaning solution L2 to the cleaning solution nozzle 541. For example, organic acids or dilute hydrofluoric acid (DHF) can be used as the cleaning solution L2. The cleaning solution nozzle 541 is held by a nozzle arm 56 and is movable together with the plating solution nozzle 531.

[0037] The rinse liquid supply unit 55 includes a rinse liquid nozzle 551 that discharges rinse liquid L3 onto a substrate W held by a substrate holding unit 52, and a rinse liquid supply source 552 that supplies rinse liquid L3 to the rinse liquid nozzle 551. The rinse liquid nozzle 551 is held by a nozzle arm 56 and is movable together with the plating solution nozzle 531 and the cleaning solution nozzle 541. For example, pure water can be used as the rinse liquid L3.

[0038] The nozzle arm 56, which holds the plating solution nozzle 531, the cleaning solution nozzle 541, and the rinsing solution nozzle 551, is configured to move horizontally and vertically by a nozzle moving mechanism (not shown). The nozzle arm 56 is movable between a discharge position, which dispenses the plating solution L1, cleaning solution L2, or rinsing solution L3 onto the substrate W, and a retracted position, which is retracted from the discharge position. The discharge position is a position that can supply the liquid to any position on the upper surface of the substrate W, for example, a position that can supply the liquid to the center of the substrate W. The retracted position is a position outside the substrate W.

[0039] A cup 571 is provided around the substrate holder 52. This cup 571 is formed in a ring shape and, when the substrate W rotates, catches any liquid splashed from the substrate W and guides it to a drain duct 581, which will be described later. An atmosphere-blocking cover 572 is provided on the outer circumference of the cup 571 to suppress the diffusion of the atmosphere around the substrate W into the chamber 51. This atmosphere-blocking cover 572 is formed in a cylindrical shape that extends vertically and has an open upper end. A lid 6, which will be described later, can be inserted into the atmosphere-blocking cover 572 from above.

[0040] A drain duct 581 is provided below the cup 571. This drain duct 581 is formed in a ring shape and receives and discharges the liquid that has been received and descended by the cup 571, as well as the processing liquid that has descended directly from around the substrate W. An inner cover 582 is provided on the inner circumference side of the drain duct 581.

[0041] The upper surface of the substrate W held by the substrate holding portion 52 is covered by the cover 6. The cover 6 has a ceiling portion 61 that extends horizontally and a side wall portion 62 that extends downward from the ceiling portion 61. When the cover 6 is positioned in the lower position (i.e., the processing position) described later, the ceiling portion 61 faces the upper substrate W held by the substrate holding portion 52 at a relatively small distance.

[0042] The ceiling portion 61 includes a first ceiling plate 611 and a second ceiling plate 612 provided on the first ceiling plate 611. The first ceiling plate 611 and the second ceiling plate 612 are provided so as to sandwich a heater 63. A seal ring 613 is provided on the outer circumference of the heater 63 between the first ceiling plate 611 and the second ceiling plate 612, and the heater 63 is sealed by this seal ring 613 so that the heater 63 does not come into contact with a liquid such as the plating solution L1. The first ceiling plate 611 and the second ceiling plate 612 may be made of a material that is suitable for having corrosion resistance to liquids such as the plating solution L1, for example, an aluminum alloy. To further enhance corrosion resistance, the first ceiling plate 611, the second ceiling plate 612 and the side wall portion 62 may be coated with Teflon®.

[0043] A lid moving mechanism 7 is connected to the lid 6 via a lid arm 71. The lid moving mechanism 7 includes a swivel motor 72 for moving the lid 6 horizontally and a cylinder 73 for moving the lid 6 vertically. The swivel motor 72 is mounted on a support plate 74 that is movably positioned vertically relative to the cylinder 73.

[0044] The swivel motor 72 of the lid movement mechanism 7 moves the lid 6 between an upper position located above the substrate W held by the substrate holding section 52 and a retracted position, which is a position retracted from the upper position. The retracted position is outside the substrate W inside the chamber 51. The rotation axis of the swivel motor 72 extends in the vertical direction, and the lid 6 is capable of swiveling horizontally between the upper position and the retracted position.

[0045] The cylinder 73 of the lid moving mechanism 7 moves the lid 6 between a lower position (shown by a solid line in Figure 6) and an upper position (shown by a dashed line in Figure 6) to adjust the distance between the substrate W, on which the plating solution L1 is applied to the upper surface, and the first ceiling plate 611 of the ceiling portion 61. When the lid 6 is positioned in the lower position, the first ceiling plate 611 is close to the substrate W.

[0046] When the lid 6 is positioned in the lower position described above, the plating solution L1 on the substrate W is heated by the heater 63.

[0047] The side wall portion 62 of the lid 6 extends downward from the peripheral edge of the first ceiling plate 611 of the ceiling portion 61, and is positioned on the outer periphery of the substrate W when the lid 6 is positioned in a lower position to heat the plating solution L1 on the substrate W.

[0048] The ceiling portion 61 and side wall portions 62 of the lid 6 are covered by a lid cover 64. This lid cover 64 is placed on the second ceiling plate 612 of the lid 6 via a plurality of support portions 65. The lid cover 64 is preferably made of a material that has higher thermal insulation properties than the ceiling portion 61 and side wall portions 62, such as a resin material, in order to suppress heat from escaping from inside the lid 6 to the surroundings.

[0049] A fan filter unit 59 is provided at the top of the chamber 51 to supply clean air around the lid 6. The fan filter unit 59 supplies air into the chamber 51 (particularly inside the atmosphere-blocking cover 572). The supplied air flows towards the exhaust pipe 81, which will be described later. A downflow is formed around the lid 6, and gas vaporized from the processing liquid, such as the plating solution L1, flows towards the exhaust pipe 81 due to this downflow. This prevents the gas vaporized from the processing liquid from rising and diffusing into the chamber 51.

[0050] The gas supplied from the fan filter unit 59 described above is discharged by the exhaust mechanism 8. This exhaust mechanism 8 has two exhaust pipes 81 located below the cup 571 and an exhaust duct 82 located below the drain duct 581. The two exhaust pipes 81 pass through the bottom of the drain duct 581 and communicate with the exhaust duct 82, respectively. The exhaust duct 82 is substantially formed in the shape of a semicircular ring when viewed from above. One exhaust duct 82 is located below the drain duct 581, and the two exhaust pipes 81 communicate with this exhaust duct 82.

[0051] In the electroless plating apparatus 300 configured in this way, first, clean air is supplied into the chamber 51 from the fan filter unit 59, and the substrate W is brought into the electroless plating apparatus 300 and held horizontally in the substrate holding section 52.

[0052] Next, the substrate W held in the substrate holder 52 is cleaned. In this cleaning process, the rotary motor 523 rotates the substrate W at a predetermined speed, moving the nozzle arm 56 from the retracted position to the discharge position, and cleaning liquid L2 is supplied from the cleaning liquid nozzle 541 to the upper surface of the rotating substrate W. This cleans the surface of the substrate W and removes any attached substances. The cleaning liquid L2 supplied to the substrate W is discharged into the drain duct 581.

[0053] Next, the substrate W is rinsed. In this rinsing process, rinsing liquid L3 is supplied to the rotating substrate W from the rinsing liquid nozzle 551, rinsing the surface of the substrate W. This washes away any remaining cleaning liquid L2 on the substrate W. The rinsing liquid L3 supplied to the substrate W is discharged into the drain duct 581.

[0054] Next, plating solution L1 is supplied to the upper surface of the substrate W held by the substrate holding unit 52, forming a paddle of plating solution L1 on the upper surface of the substrate W. When forming the paddle on the upper surface of the substrate W, first, with the substrate W rotating at a lower rotation speed than during the rinsing process, the plating solution L1 is discharged from the plating solution nozzle 531 onto the upper surface of the substrate W. This plating solution L1 remains on the upper surface due to surface tension, forming a layer of plating solution L1, known as a paddle. A portion of the plating solution L1 flows out from the upper surface and is discharged through the drain duct 581. After a predetermined amount of plating solution L1 has been discharged from the plating solution nozzle 531, the discharge of the plating solution L1 is stopped. Then, the nozzle arm 56 is retracted to the retracted position. By forming the paddle while rotating the substrate W in this way, the plating film can be made uniform. Alternatively, the rotation of the substrate W may be stopped to increase the amount of plating solution L1 applied.

[0055] Next, a process of heating the plating solution L1 applied to the substrate W is carried out. This plating solution heating process includes the operation of covering the substrate W with a lid 6, the operation of supplying an inert gas, the operation of actually heating the plating solution L1 by positioning the lid 6 in a lower position, and the operation of moving the lid 6 away from the substrate W. It is preferable that the rotation speed of the substrate W (including when it is stopped) is maintained during the heating process of the plating solution L1 in the same way as during the application of the plating solution.

[0056] The operation of supplying inert gas involves supplying inert gas to the space between the substrate W held by the substrate holding section 52 and the lid 6 located below it, thereby maintaining a low-oxygen atmosphere around the substrate W while performing the plating treatment on the upper surface of the substrate W.

[0057] When the plating solution L1 is actually heated, its temperature rises to the temperature at which its components precipitate. As a result, the components of the plating solution L1 precipitate on the upper surface of the substrate W, forming and growing a plating film (Ru film). This heating operation is performed for the time necessary to obtain a plating film of the desired thickness, while maintaining the temperature of the plating solution L1 at the temperature at which the plating film precipitates, for example, 50-85°C.

[0058] Next, the substrate W is rinsed. In this rinsing process, first, the rotation speed of the substrate W is increased to a speed higher than that used during the plating process (paddle formation and heating), for example, the substrate W is rotated at the same rotation speed as the substrate rinsing process before the plating process. Subsequently, the rinsing liquid nozzle 551 is moved from the retracted position to the discharge position. Next, the rinsing liquid L3 is supplied from the rinsing liquid nozzle 551 to the rotating substrate W to wash away any remaining plating solution L1 on the substrate W.

[0059] Next, the substrate W is dried. In this drying process, the substrate W is rotated at high speed to shake off any remaining rinse solution L3 on the substrate W and dry it. This results in a substrate having a Ru film, which is an electroless plating film, in a dried state. In this case, an inert gas such as N2 gas may be blown onto the substrate W to accelerate drying.

[0060] Subsequently, the substrate W is removed from the substrate holder 52 and unloaded from the electroless plating apparatus 300.

[0061] In practice, the electroless plating apparatus 300 is configured as a unit with multiple units arranged together. It is located at the loading / unloading station, and a transport mechanism transports substrates from a substrate storage container that holds multiple substrates to one of the electroless plating apparatuses 300 for processing.

[0062] [Inert Gas Plasma Treatment System] Figure 7 is a cross-sectional view showing an example of an inert gas plasma processing apparatus 400. The inert gas plasma processing apparatus 400 performs plasma treatment with an inert gas on a Ru film formed by electroless plating, and is configured as a capacitively coupled plasma processing apparatus.

[0063] This inert gas plasma processing apparatus 400 has a processing chamber 210 that is substantially cylindrical and made of metal, for example, aluminum whose surface has been anodized. This processing chamber 210 is grounded for safety.

[0064] A cylindrical metal support base 214 is positioned at the bottom of the processing container 210 via an insulating plate 212 made of ceramics or the like, and a substrate mounting base 216 made of metal, such as aluminum, is provided on top of this support base 214. The substrate mounting base 216 constitutes the lower electrode. The substrate mounting base 216 has an electrostatic chuck 218 on its upper surface that attracts and holds the substrate W by electrostatic force. This electrostatic chuck 218 has a structure in which an electrode 220 is provided inside an insulator, and by applying a DC voltage from a DC power supply 222 for attraction to the electrode 220, the substrate W is attracted and held by electrostatic force such as Coulomb force.

[0065] A conductive focus ring 224, made of, for example, silicon, is positioned around the electrostatic chuck 218 to improve the uniformity of the plasma treatment. Cylindrical inner wall members 226, made of, for example, quartz, are provided on the sides of the substrate mounting table 216 and the support table 214.

[0066] A temperature control mechanism 228 is provided inside the support base 214. A temperature control medium is circulated and supplied to this temperature control mechanism 228 via pipes 230a and 230b from an external chiller unit (not shown). A heater 219 is also provided inside the substrate mounting base 216. The temperature control mechanism 228 and heater 219 control the temperature of the substrate W to a desired temperature, for example, in the range of 70 to 400°C.

[0067] Furthermore, a heat transfer gas, such as He gas, from a heat transfer gas supply mechanism (not shown) is supplied between the upper surface of the electrostatic chuck 218 and the back surface of the substrate W via the gas supply line 232.

[0068] An upper electrode 234 is provided above the substrate mounting table (lower electrode) 216, facing the substrate mounting table 216. The space between the upper electrode 234 and the substrate mounting table (lower electrode) 216 becomes the plasma generation space.

[0069] The upper electrode 234 is supported on the upper part of the processing container 210 via an insulating shielding member 243. The upper electrode 234 consists of an electrode plate 236 that forms the surface facing the substrate mounting base 216 and has a number of gas discharge holes 237, and a water-cooled electrode support 238 that detachably supports the electrode plate 236. A gas diffusion chamber 240 is provided inside the electrode support 238, and a number of gas passage holes 241 that communicate with the gas discharge holes 237 extend downward from this gas diffusion chamber 240. A gas inlet 242 is formed in the electrode support 238 to guide inert gas to the gas diffusion chamber 240, and a gas pipe 251 connected to a gas supply unit 250, which will be described later, is connected to this gas inlet 242. The inert gas supplied from the gas supply unit 250 is supplied to the gas diffusion chamber 240 and then supplied to the plasma generation space in the processing container 210 via the gas passage holes 241 and gas discharge holes 237. In other words, the upper electrode 234 is configured as a shower head.

[0070] The gas supply unit 250 supplies an inert gas for generating plasma and includes a gas source, piping, and a flow rate controller. The inert gas from the gas supply unit 250 is supplied to the gas diffusion chamber 240 via the gas piping 251 as described above. As the inert gas supplied from the gas supply unit 250, noble gases such as Ar gas and He gas, or N2 gas can be used. Among these, Ar gas, which has a large number of atoms and strong physical effects, is preferred. Two or more inert gases may be mixed.

[0071] An exhaust port 260 is provided at the bottom of the processing container 210, and an exhaust device 264 is connected to this exhaust port 260 via an exhaust pipe 262. The exhaust device 264 has an automatic pressure control valve and a vacuum pump, and this exhaust device 264 is capable of exhausting the inside of the processing container 210 and maintaining the inside of the processing container 210 at a desired vacuum level. An inlet / outlet 265 for loading and unloading substrates W into and out of the processing container 210 is provided on the side wall of the processing container 210, and this inlet / outlet 265 is configured to be opened and closed by a gate valve 266.

[0072] A first high-frequency power supply 288 for plasma generation is electrically connected to the upper electrode 234. A first matching unit 287 is interposed in the feed line 289 that supplies power from the first high-frequency power supply 288 to the upper electrode 234. When high-frequency power is supplied from the first high-frequency power supply 288 to the upper electrode 234, a high-frequency electric field is formed in the plasma generation space between the upper electrode 234 and the substrate mounting base (lower electrode) 216, and a capacitively coupled plasma is generated. The high-frequency power supplied from the first high-frequency power supply 288 may have a frequency of 0.4 to 100 MHz and a power of 100 to 3000 W. The first matching unit 287 is used to match the load (plasma) impedance to the impedance on the first high-frequency power supply 288 side.

[0073] A second high-frequency power supply 292 for bias application is electrically connected to the substrate mounting table 216, which is the lower electrode. A second matching unit 291 is interposed in the power supply line 293 that supplies power from the second high-frequency power supply 292 to the substrate mounting table 216. When high-frequency power is supplied from the second high-frequency power supply 292 to the substrate mounting table 216, a bias is applied to the substrate W, and ions are attracted to the substrate W. In this way, by applying a bias to the substrate W and attracting ions in the plasma, especially Ar ions, to the substrate, the physical effect on the Ru film on the substrate surface can be increased. The high-frequency power supplied from the second high-frequency power supply 292 may have a frequency of 0.4 to 100 MHz and a power of 100 to 1000 W. The second matching unit 291 is for matching the load (plasma) impedance to the impedance of the second high-frequency power supply 292. The second high-frequency power supply 292 is not essential, but it is preferable to provide it in order to increase the physical effect on the substrate W.

[0074] In the inert gas plasma processing apparatus 400 configured in this way, first, the substrate W is brought into the processing container 210 and placed on the substrate mounting table 216. At this time, the temperature of the substrate mounting table 216 is controlled by the temperature control mechanism 228 and the heater 219 so that the temperature of the placed substrate W is 70 to 400°C, preferably 70 to 130°C, and even more preferably 100 to 130°C.

[0075] Next, after evacuating the processing container 210, an inert gas is supplied to the processing container 210 while the pressure inside the processing container 210 is adjusted to, for example, 100 mTorr to 2 Torr (13.3 to 266.6 Pa).

[0076] In this state, by supplying an inert gas from the gas supply unit 250 and supplying high-frequency power to the upper electrode 234 from the first high-frequency power supply 288 for plasma generation, a capacitively coupled plasma is generated in the plasma generation space, and the physical effects of the plasma are exerted on the Ru film on the surface of the substrate W. Furthermore, by supplying high-frequency power to the lower electrode, the substrate mounting table 216, from the second high-frequency power supply 292 for bias application, a bias is applied to the substrate W, and ions in the plasma are drawn into the substrate W. This increases the physical effects on the Ru film. In particular, by using Ar gas, which has a large number of atoms, as the inert gas, the physical effects on the Ru film can be further enhanced.

[0077] After performing the plasma treatment described above for a predetermined time, for example, 5 to 300 seconds, the plasma is turned off, the inside of the treatment container 210 is purged with an inert gas, and then the material is removed from the treatment container 210.

[0078] In this example, a capacitively coupled plasma was used, but other plasmas such as inductively coupled plasma or microwave plasma may also be used.

[0079] Furthermore, the inert gas plasma processing apparatus 400 is actually connected to a vacuum-sealed vacuum transport chamber, and is incorporated into a system configured such that substrates are transported from a substrate storage container located at the loading / unloading station to the inert gas plasma processing apparatus 400 via a load lock chamber and a transport mechanism within the vacuum transport chamber.

[0080] [Reduction treatment device] Figure 8 is a cross-sectional view showing an example of a reduction processing apparatus 500. The reduction processing apparatus 500 includes a processing container 310, a heating plate 320, and a gas supply unit 330.

[0081] The processing container 310 is a cylindrical metal container with a nearly sealed structure, and the inside is maintained at atmospheric pressure. A heating plate 320 is provided in the center of the bottom of the processing container 310. An inlet / outlet 311 for loading and unloading substrates W is formed in the side wall of the processing container 310, and the inlet / outlet 311 is opened and closed by a shutter 312. In addition, a gas inlet 313 for introducing reducing gas is formed in the center of the top wall of the processing container 310, and a number of exhaust ports 314 are formed on the outside of the heating plate 320 on the bottom wall.

[0082] Heating plate 320 is, gold This device is made of metal and heats a substrate W placed on its top surface, with a heater 321 embedded inside. The heater 321 heats the heating plate 320 so that the temperature of the substrate W placed on it reaches 200 to 430°C, for example, 400°C.

[0083] The gas supply unit 330 supplies reducing gas into the processing container 310 via piping 331 and gas inlet 313. As the reducing gas, foaming gas, H2 gas, formic acid, etc., can be used.

[0084] In the reduction processing apparatus 500 configured in this way, first, the substrate W, which has undergone plasma treatment with an inert gas, is transported into the processing container 310 by a transport mechanism (not shown) and placed on the heating plate 320. At this time, the temperature of the heating plate 320 is controlled by a heater 321 so that the temperature of the placed substrate W is 200 to 430°C, for example, 400°C.

[0085] Next, reducing gas is supplied from the gas supply unit 330 into the processing container 310, and the substrate W on the heating plate 320 is subjected to a reduction treatment. This reduces the oxidized parts of the Ru film and promotes the crystallization of the Ru film, thereby lowering its resistance. The processing time at this stage may be approximately 5 to 120 minutes.

[0086] After supplying reducing gas for a predetermined time, the supply of reducing gas is stopped, and the substrate on the heating plate 320 is removed from the processing container 310 by a transport mechanism (not shown).

[0087] The reduction processing device 500, which is configured as a reduction annealing device, is actually incorporated into a system in which substrates are transported from substrate storage containers located at the loading / unloading station to the reduction processing device 500 by a transport mechanism.

[0088] In the above example, a reduction treatment apparatus 500 that performs reduction annealing at atmospheric pressure was described, but a hydrogen plasma treatment apparatus that performs hydrogen plasma treatment may also be used as the reduction treatment apparatus 500. Such a hydrogen plasma treatment apparatus has a structure similar to the inert gas plasma treatment apparatus 400 shown in Figure 7, and the gas supplied from the gas supply unit can be H2 gas or H2 gas + inert gas. However, in the case of a hydrogen plasma treatment apparatus, a high-frequency power supply for biasing does not need to be used. In addition, the gas supply unit 250 of the inert gas plasma treatment apparatus 400 shown in Figure 7 may be equipped with an H2 gas supply function so that reduction treatment can be performed in the inert gas plasma treatment apparatus 400.

[0089] When a reduction annealing apparatus is used as the reduction treatment apparatus 500, it is necessary to bring the pressure from the inert gas plasma treatment apparatus 400, where vacuum treatment is performed, to atmospheric pressure. In contrast, when the reduction treatment is hydrogen plasma treatment, it is a vacuum treatment, so both inert gas plasma treatment and hydrogen plasma treatment can be performed in a single vacuum system, which is efficient. Furthermore, by enabling hydrogen plasma treatment in the inert gas plasma treatment apparatus 400 (performing both the inert gas plasma treatment apparatus 400 and the reduction treatment apparatus 500 in a single apparatus), an even more efficient substrate processing system can be realized.

[0090] [Substrate transport mechanism] The substrate transport mechanisms 600 and 700 transport substrates in multiple substrate storage containers between the electroless plating apparatus 300 and the inert gas plasma processing apparatus 400, and between the inert gas plasma processing apparatus 400 and the reduction processing apparatus 500, respectively. It is preferable that the substrate transport mechanisms 600 and 700 transport the substrate storage containers while maintaining them in a non-oxidizing atmosphere such as an inert atmosphere or a reducing atmosphere, so as to suppress oxidation of the Ru film formed by electroless plating.

[0091] [Control Unit] The control unit 800 controls each component of the substrate processing system 200, namely the electroless plating apparatus 300, the inert gas plasma processing apparatus 400, the reduction processing apparatus 500, and the substrate transport mechanisms 600 and 700. The control unit 800 has a main control unit with a CPU (computer), an input device, an output device, a display device, and a storage device. The main control unit of the control unit 800 causes the substrate processing system 200 to perform a desired operation based, for example, a processing recipe stored in a storage medium built into the storage device or a storage medium set in the storage device.

[0092] In the substrate processing system 200, the substrate processing method of one embodiment can be realized by operating the electroless plating apparatus 300, the inert gas plasma processing apparatus 400, and the reduction processing apparatus 500, all configured as described above, under the control of the control unit 800.

[0093] <Example of experiment> Here, we prepared three samples of Ru films formed by electroless plating: one in the as-depo state (Sample 1), one that underwent only reduction annealing after plating (Sample 2), and three that underwent Ar plasma treatment followed by reduction annealing (Samples 3 and 4). For reduction annealing, we used a forming gas (4% H2) as the reducing gas and performed the treatment at 400°C for 10 minutes. For Ar plasma treatment, we used 100% Ar gas, with common conditions of high-frequency power (HF): 1500W to the upper part, high-frequency power (LF): 500W to the lower part, and a time of 100 sec. The pressure and temperature were varied between Sample 3 and Sample 4. Specifically, for Sample 3, the pressure was 300 mTorr and the temperature was 80°C, while for Sample 4, the pressure was 200 mTorr and the temperature was 120°C.

[0094] SEM observation revealed that in sample 1, which was in the as-depo state, crystal growth had not progressed sufficiently, and it was close to an amorphous state. In sample 2, which underwent only reduction annealing, crystal growth was observed, but numerous cracks were also seen. Among the samples treated with Ar plasma, sample 3 showed almost no cracks in the film, but a few defects were found within the film, while sample 4 showed almost no cracks or defects in the film.

[0095] When the resistivity of the films was measured, sample 1 in the as-depo state had a resistivity of 113 μΩ·cm, sample 2 which underwent only reduction annealing had a resistivity of 43.7 μΩ·cm, while samples 3 and 4, which underwent Ar plasma treatment, both showed a low resistivity of 15.1 μΩ·cm.

[0096] From these results, it was confirmed that a sound, low-resistance Ru film can be obtained by performing Ar plasma treatment on a Ru film formed by electroless plating, followed by a reduction treatment.

[0097] <Other applications> Although embodiments have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0098] For example, the electroless plating apparatus in the above embodiment is merely illustrative, and apparatuses with various other configurations can be used. Also, in the above embodiment, the inert gas plasma processing apparatus is merely illustrative, and apparatuses with various other configurations can be used. Furthermore, as for the plasma, as mentioned above, it is not limited to capacitively coupled plasma, but other plasmas such as inductively coupled plasma or microwave plasma may be used.

[0099] Furthermore, although the above embodiment shows a case where a semiconductor substrate (semiconductor wafer) having a semiconductor substrate is used as the substrate, the substrate is not limited to a semiconductor wafer, but may be other substrates such as an FPD (flat panel display) substrate or a ceramic substrate. Moreover, although the above embodiment shows a case in which a Ru film is embedded in fine vias, it is not limited to this. [Explanation of symbols]

[0100] 101;Lower layer wiring 102; insulating film 102a; Nitride film 102b; Oxide film 103; Via 105;Ru film 110;Structure section 200; Substrate processing system 300; Electroless plating apparatus 400; Inert gas plasma processing apparatus 500; Reduction treatment device 600, 700; Substrate transport mechanism 800; Control Unit W; substrate

Claims

1. A process of forming a Ru film on a substrate by electroless plating, A step of treating the substrate on which the Ru film is formed with an inert gas plasma, The process involves reducing the substrate after the treatment with the inert gas plasma, A substrate processing method having the following characteristics.

2. The substrate processing method according to claim 1, wherein the step of forming the Ru film by electroless plating comprises applying an electroless plating solution to the substrate, heating the substrate to deposit a plating film that will become the Ru film, and drying the substrate.

3. The substrate processing method according to claim 2, wherein the heating of the substrate is performed at 50 to 85°C.

4. In the plasma treatment of the inert gas, the inert gas is Ar gas or N ２ A substrate processing method according to claim 1, comprising a gas.

5. The substrate processing method according to claim 4, wherein the plasma treatment with the inert gas is performed while a bias is applied to the substrate.

6. The substrate has a lower layer wiring, an insulating film formed on the lower layer wiring, and vias provided in the insulating film such that the lower layer wiring is exposed on the bottom surface. The substrate processing method according to any one of claims 1 to 5, wherein the Ru film is grown from the lower layer wiring using the lower layer wiring as a catalyst in a bottom-up manner.

7. The substrate processing method according to any one of claims 1 to 5, wherein the step of reducing the substrate is performed by reducing annealing, in which the substrate is heated at atmospheric pressure while a reducing gas is supplied.

8. The reducing gas is a foaming gas, H ２ The substrate processing method according to claim 7, wherein the material is at least one selected from the group consisting of gas and formic acid.

9. The substrate processing method according to claim 7, wherein the heating temperature of the substrate in the step of reducing the substrate is in the range of 200 to 430°C.

10. The step of reducing the substrate is H ２ A substrate processing method according to any one of claims 1 to 5, which is performed by hydrogen plasma processing, in which the substrate is processed by a plasma of a gas containing gas.

11. The substrate processing method according to any one of claims 1 to 5, wherein the step of processing with plasma of the inert gas is performed at a pressure in the range of 13.3 to 266.6 Pa.

12. The substrate processing method according to any one of claims 1 to 5, wherein the step of processing with plasma of the inert gas is performed at a temperature in the range of 70 to 400°C.

13. The substrate processing method according to any one of claims 1 to 5, wherein the time for the step of processing with plasma of the inert gas is 5 to 300 seconds.

14. An electroless plating apparatus for forming a Ru film on a substrate by electroless plating, The substrate on which the Ru film has been formed by the electroless plating apparatus is subjected to treatment with an inert gas plasma treatment apparatus, A reduction apparatus for reducing the substrate that has been treated by the inert gas plasma apparatus, A substrate processing system having the following features.

15. In the aforementioned inert gas plasma processing apparatus, the inert gas is Ar gas or N ２ A substrate processing system according to claim 14, comprising a gas.

16. The substrate processing system according to claim 15, wherein the inert gas plasma processing apparatus has bias application means for applying a bias to the substrate.

17. The substrate processing system according to any one of claims 14 to 16, wherein the reduction processing apparatus is a reduction annealing apparatus that heats the substrate at atmospheric pressure while supplying a reducing gas.

18. The reduction apparatus is H ２ A substrate processing system according to any one of claims 14 to 16, which is a hydrogen plasma processing apparatus for processing a substrate with a gas-containing plasma.

Images