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 technology]

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

[0003] [Patent Document 1] International Publication No. 2019 / 151078 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a substrate processing method and a substrate processing system capable of forming a healthy, low-resistance Ru film by using electroless plating. [Means for solving the problem]

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

[0006] According to the present disclosure, there is provided a substrate processing method and a substrate processing system capable of forming a healthy, low-resistance Ru film by using electroless plating. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing a state in which cracks are generated when a Ru film is formed by electroless plating and then subjected to reduction annealing. [Diagram 2] 1 is a flowchart illustrating a substrate processing method according to an embodiment. [Diagram 3] 1 is a cross-sectional view showing an example of a structure of a substrate for which a substrate processing method according to an embodiment is used; [Figure 4] 4 is a cross-sectional view showing a state in which a Ru film is embedded in a via formed in the substrate of FIG. 3 by electroless plating. [Diagram 5] 1 is a block diagram showing a substrate processing system for carrying out a substrate processing method according to an embodiment; [Figure 6] 6 is a cross-sectional view showing an example of an electroless plating apparatus included in the substrate processing system of FIG. 5. [Figure 7] 6 is a cross-sectional view showing an example of an inert gas plasma processing apparatus included in the substrate processing system of FIG. 5. [Figure 8] 6 is a cross-sectional view showing an example of a reduction treatment device included in the substrate processing system of FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment will be described with reference to the accompanying drawings.

[0009] <Background> First, the background will be explained. The above-mentioned Patent Document 1 describes the formation of a film containing Cu, Co, Ni or Ru in 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, Ru is not sufficiently crystallized in the as-depo state, and the grain size is minute and the state is close to amorphous. For this reason, the resistance of the Ru film in the as-depo state is high.

[0010] For this reason, it is conceivable that after a Ru film is formed by electroless plating, the Ru film may be subjected to a reduction treatment such as reduction annealing to decompose the Ru oxide and promote crystallization.

[0011] However, it was found that when a reduction treatment such as reduction annealing is performed on an as-depo Ru film formed by electroless plating, cracks C occur along the crystal grain boundaries of the Ru film, as shown in the schematic diagram in Figure 1. The main cause of the cracks is thought to be that Ru is easily oxidized and oxides are formed between the grains of Ru, which causes oxygen to be released during the reduction treatment, degrading the adhesion between the Ru grains, and that the reduction treatment promotes crystallization, causing volumetric shrinkage.

[0012] Therefore, in one embodiment, as a post-treatment after forming a Ru film by electroless plating, the substrate is treated with plasma of an inert gas such as Ar gas or N2 gas, and then a reduction treatment is performed. When the substrate is treated with 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. Therefore, the adhesion between the grains is not deteriorated, and cracks due to volumetric shrinkage when crystallization is promoted by the subsequent reduction treatment are suppressed, and a healthy and low-resistance Ru film can be formed.

[0013] <Substrate processing method> Next, the substrate processing method according to the embodiment will be described in more detail. FIG. 2 is a flowchart showing a substrate processing method according to an embodiment. The substrate processing method of this embodiment includes a step of forming a Ru film on a substrate by electroless plating (step ST1), a step of treating the substrate after the Ru film is formed with an inert gas plasma (step ST2), and a step of reducing 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 base such as silicon can be used. For example, the substrate may have a structure as shown in FIG. 3. The substrate W in FIG. 3 has a structure 110 provided on a Si base (not shown). The structure 110 has a lower wiring 101 and an insulating film 102 formed on the lower wiring 101, and a fine via 103 is formed in the insulating film 102. The lower wiring 101 is exposed at the bottom of the via 103. The insulating film 102 has a lower nitride film 102a and an upper oxide film 102b. The lower wiring 101 can be preferably made of Cu or Ru. Alternatively, Ni or Co can be used.

[0015] The electroless plating process in step ST1 is performed by applying a chemical solution (plating solution) for electroless plating onto a substrate, followed by heating. The heating temperature is preferably 60 to 70° C. After heating, the substrate is subjected to a drying process.

[0016] When the substrate has the structure shown in Fig. 3, an electroless plating process is performed to embed a Ru film 105 in the via 103, as shown in Fig. 4. At this time, the Ru film 105 grows bottom-up from the bottom surface of the via 103 using the lower wiring 101 exposed at the bottom surface of the via 103 as a catalyst.

[0017] In step ST2, a process of performing a treatment using an inert gas plasma is performed by exposing the substrate on which the Ru film is formed by electroless plating to an inert gas plasma, and the physical action of the plasma is applied to the Ru film. This destroys the Ru grains in the Ru oxide film, and decomposes the Ru oxide formed by the oxidation of the Ru film.

[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, preferably 70 to 130°C, more preferably 100 to 130°C. If the temperature exceeds 130°C, degassing tends to increase. The treatment time in step ST2 may be 5 to 300 seconds. As the inert gas, rare gases such as Ar gas and He gas, and N2 gas can be used. Among these, Ar gas and N2 gas are preferred, and Ar gas, which has a large atomic number and a large physical action, is particularly preferred. The gas may be 100% Ar gas, or two or more inert gases such as Ar gas + He gas or Ar gas + N2 gas may be mixed. 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] 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, and the physical action on the Ru film on the substrate surface can be increased. In particular, a large effect can be obtained by using Ar ions having a large atomic number. The bias may be a high-frequency bias.

[0020] The process of reducing the substrate in step ST3 is a process of reducing the oxidized portion of the Ru film and promoting the crystallization of the Ru film to reduce the resistance of the Ru film.

[0021] The reduction treatment may be reduction annealing or hydrogen plasma treatment. Reduction annealing is a treatment in which a substrate is heated while a reduction gas is supplied, and is a normal pressure treatment. Hydrogen plasma treatment is a treatment in which a substrate is treated with a gas containing H2 gas, for example, H2 gas alone or H2 gas + inert gas plasma, and is a vacuum treatment.

[0022] When the reduction treatment is reduction annealing, the substrate temperature may be 200 to 430°C, for example, 400°C. Examples of the reduction gas include forming gas, H2 gas, formic acid, etc., and at least one of these may be suitably used. The forming gas is a mixed gas of H2 gas and N2 gas, and H2 gas may be 5.7% or less, which is the explosion limit, for example, 4%, which is used. The reduction annealing time may be about 5 to 120 minutes, depending on the thickness of the Ru film. The reduction annealing is a normal pressure treatment, and is preferably performed using an apparatus with a sealed structure so that the gas composition can be maintained.

[0023] When the reduction treatment is a hydrogen plasma treatment, the treatment 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, preferably in the range of 70 to 130°C, more preferably in the range of 100 to 130°C. The hydrogen plasma treatment can be performed using plasma of H2 gas or H2 gas + inert gas. The plasma 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 a hydrogen plasma treatment, the treatment may be performed in the same apparatus as the inert gas plasma treatment in step ST2.

[0024] As described above, in this embodiment, after the inert gas plasma treatment in step ST2, the reduction treatment in step ST3 is performed, thereby suppressing the decrease in adhesion between grains due to oxygen desorption and the occurrence of cracks due to the promotion of crystallization during the reduction treatment.

[0025] In other words, the treatment with the inert gas plasma in step ST2 destroys the Ru grains and decomposes the Ru oxides, thereby suppressing deterioration of adhesion between the grains and suppressing cracks due to volumetric shrinkage caused by the subsequent reduction treatment.

[0026] The reaction model of the plasma processing in step ST2 is assumed to be similar to the destruction and amorphization of silicon crystals that occurs when impurities are doped into a silicon substrate by implantation.

[0027] As described above, according to this embodiment, the Ru film formed by electroless plating can be reduced without generating cracks, and a healthy Ru film with low resistance can be formed.

[0028] In addition, when a substrate having a structure in which fine vias 103 are formed as shown in FIG. 3 is used and a Ru film is embedded in the vias 103, it is difficult to embed voids by conventional CVD or PVD, but by using electroless plating as in this embodiment, it is possible to embed the vias 103 without voids. That is, in the case of electroless plating, Ru selectively grows from the lower wiring 101 using the lower wiring 101 exposed on the bottom surface of the via 103 as a catalyst, and is embedded by bottom-up growth, so that even fine vias can be embedded without voids. In addition, the temperature during film formation is low, less than 100° C. In addition, in this embodiment, as described above, a low-resistance Ru film can be obtained by electroless plating without generating cracks, so that the advantage of embedding Ru in such vias by electroless plating can be effectively exhibited.

[0029] <Substrate processing system> Next, a substrate processing system for carrying out the above substrate processing method will be described. FIG. 5 is a block diagram showing a substrate processing system for carrying out a substrate processing method according to an 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. Substrates are transported 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, 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. Each of these will be described below individually.

[0031] [Electroless plating equipment] Fig. 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 Fig. 6, includes a chamber 51, a substrate holding unit 52, and a plating solution supply unit 53. The substrate holding unit 52 is disposed in the chamber 51, and has a chuck member 521 that vacuum-adsorbs the lower surface (rear surface) of the substrate W, and holds the substrate W horizontally. The substrate holding unit 52 may be a mechanical chuck. The plating solution supply unit 53 supplies a plating solution L1 to the upper surface (processing surface) of the substrate W held by the substrate holding unit 52.

[0032] A rotary motor 523 is connected to the substrate holding part 52 via a rotary shaft 522. When the rotary motor 523 is driven, the substrate holding part 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 has a plating solution nozzle 531 that discharges the plating solution L1 onto the substrate W held by the 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, the temperature of which is adjusted to a predetermined temperature, to the plating solution nozzle 531. The plating solution nozzle 531 is held by a nozzle arm 56 and 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 contain appropriate additives. The plating solution L1 is discharged from the plating solution nozzle 531, so that a Ru film is applied onto 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 a 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 a rinsing liquid L3 to the upper surface of the substrate W.

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

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

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

[0039] A cup 571 is provided around the substrate holding part 52. This cup 571 is formed in a ring shape, and receives liquid scattered from the substrate W when the substrate W rotates, and guides it to a drain duct 581 described later. An atmosphere blocking cover 572 is provided on the outer periphery of the cup 571, and prevents the atmosphere around the substrate W from diffusing into the chamber 51. This atmosphere blocking cover 572 is formed in a cylindrical shape so as to extend in the vertical direction, and has an open upper end. A lid body 6 described later can be inserted into the atmosphere blocking cover 572 from above.

[0040] A drain duct 581 is provided below the cup 571. The drain duct 581 is formed in a ring shape, and receives and discharges the liquid received by the cup 571 and descending, or the processing liquid that descends directly from the periphery of the substrate W. An inner cover 582 is provided on the inner peripheral side of the drain duct 581.

[0041] The upper surface of the substrate W held by the substrate holding part 52 is covered by a lid 6. The lid 6 has a ceiling part 61 extending horizontally and a side wall part 62 extending downward from the ceiling part 61. When the lid 6 is located at a lower position (i.e., a processing position) described below, the ceiling part 61 faces the substrate W above the substrate W held by the substrate holding part 52 with a relatively small gap therebetween.

[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 the heater 63. A seal ring 613 is provided between the first ceiling plate 611 and the second ceiling plate 612 on the outer periphery side of the heater 63, 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 liquid L1. The first ceiling plate 611 and the second ceiling plate 612 may be formed of a material that is suitable for having corrosion resistance against a liquid such as the plating liquid L1, for example, an aluminum alloy. In order to further increase the corrosion resistance, the first ceiling plate 611, the second ceiling plate 612, and the side wall portion 62 may be coated with Teflon (registered trademark).

[0043] A lid moving mechanism 7 is connected to the lid 6 via a lid arm 71. The lid moving mechanism 7 has a rotation motor 72 that moves the lid 6 horizontally, and a cylinder 73 that moves the lid 6 up and down. The rotation motor 72 is attached to a support plate 74 that is provided so as to be movable up and down relative to the cylinder 73.

[0044] The swivel motor 72 of the lid moving mechanism 7 moves the lid 6 between an upper position located above the substrate W held by the substrate holder 52 and a retracted position retracted from the upper position. The retracted position is a position outside the substrate W in the chamber 51. The rotation axis of the swivel motor 72 extends in the vertical direction, and the lid 6 is capable of swivel movement in the horizontal direction 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 (position shown by a solid line in FIG. 6) and an upper position (position shown by a two-dot chain line in FIG. 6) to adjust the distance between the substrate W, on whose upper surface the plating solution L1 is poured, and the first ceiling plate 611 of the ceiling portion 61. When the lid 6 is disposed in the lower position, the first ceiling plate 611 comes close to the substrate W.

[0046] When the lid 6 is located at the above-mentioned lower position, the plating solution L1 on the substrate W is heated by the heater 63.

[0047] The side wall portion 62 of the lid body 6 extends downward from the peripheral portion 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 body 6 is positioned in a lower position to heat the plating solution L1 on the substrate W.

[0048] The ceiling 61 and side wall 62 of the lid 6 are covered by a lid cover 64. This lid cover 64 is placed on a second ceiling plate 612 of the lid 6 via a plurality of supports 65. In order to prevent heat from escaping from within the lid 6 to the surroundings, the lid cover 64 is preferably formed from a material having higher thermal insulation properties than the ceiling 61 and side wall 62, such as a resin material.

[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, into the atmosphere blocking cover 572). The supplied air flows toward an exhaust pipe 81, which will be described later. A downflow in which the air flows downward is formed around the lid 6, and gas vaporized from the processing liquid, such as the plating liquid L1, flows toward the exhaust pipe 81 by 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 is exhausted by the exhaust mechanism 8. The exhaust mechanism 8 has two exhaust pipes 81 provided below the cup 571 and an exhaust duct 82 provided below the drain duct 581. The two exhaust pipes 81 penetrate the bottom of the drain duct 581 and are each connected to the exhaust duct 82. The exhaust duct 82 is formed in a substantially semicircular ring shape when viewed from above. One exhaust duct 82 is provided below the drain duct 581, and two exhaust pipes 81 are connected to this exhaust duct 82.

[0051] In the electroless plating apparatus 300 configured as described above, first, with clean air being supplied into the chamber 51 from the fan filter unit 59, the substrate W is loaded into the electroless plating apparatus 300 and held horizontally by the substrate holding portion 52.

[0052] Next, a cleaning process is performed on the substrate W held by the substrate holder 52. In this cleaning process, the substrate W is rotated at a predetermined rotation speed by the rotary motor 523, the nozzle arm 56 is moved from the retracted position to the discharge position, and the 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 deposits and the like. The cleaning liquid L2 supplied to the substrate W is discharged into the drain duct 581.

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

[0054] Next, the plating solution L1 is supplied to the upper surface of the substrate W held by the substrate holder 52, and a puddle of the plating solution L1 is formed on the upper surface of the substrate W. When forming a puddle on the upper surface of the substrate W, the plating solution L1 is discharged from the plating solution nozzle 531 onto the upper surface of the substrate W while the substrate W is rotated at a rotation speed lower than that during the rinsing process. The plating solution L1 remains on the upper surface due to surface tension, and a so-called puddle, which is a layer of the plating solution L1, is formed. A part of the plating solution L1 flows out from the upper surface and is discharged through the drain duct 581. After a predetermined amount of the plating solution L1 is 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 a puddle while rotating the substrate W in this way, the plating film can be made uniform. The rotation of the substrate W may be stopped to increase the amount of plating solution L1 applied.

[0055] Next, a process is performed to heat the plating solution L1 piled on the substrate W. This plating solution heating process includes the steps of covering the substrate W with the lid 6, supplying an inert gas, placing the lid 6 in a lower position to actually heat the plating solution L1, and retracting the lid 6 from above the substrate W. Note that, even during the process of heating the plating solution L1, it is preferable that the rotation speed of the substrate W (including when it is stopped) is maintained in the same manner as when the plating solution was piled.

[0056] The operation of supplying the inert gas is intended to supply the inert gas into the space between the substrate W held by the substrate holding portion 52 and the lid body 6 located at a lower position, thereby performing plating processing on the upper surface of the substrate W while maintaining a low-oxygen atmosphere around the substrate W.

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

[0058] Next, the substrate W is rinsed. In this rinse, the rotation speed of the substrate W is increased to be higher than the rotation speed during the plating (puddle formation and heating), for example, the substrate W is rotated at the same rotation speed as the substrate rinsing before the plating. Next, the rinse liquid nozzle 551 is moved from the retreated position to the discharge position. Next, the rinse liquid L3 is supplied from the rinse liquid nozzle 551 to the rotating substrate W to wash away the plating liquid L1 remaining on the substrate W.

[0059] Next, a drying process is performed on the substrate W. In this drying process, the substrate W is rotated at high speed to shake off the rinsing liquid L3 remaining 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 sprayed onto the substrate W to promote drying.

[0060] Thereafter, the substrate W is removed from the substrate holder 52 and carried out from the electroless plating apparatus 300.

[0061] In reality, multiple electroless plating apparatuses 300 are arranged as a unit, and are placed at a loading / unloading station. A transport mechanism is used to transport a substrate from a substrate storage container that stores multiple substrates to one of the electroless plating apparatuses 300 for processing.

[0062] [Inert gas plasma processing equipment] 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 processing using an inert gas on a Ru film formed by electroless plating, and is configured as a capacitively coupled plasma processing apparatus.

[0063] The inert gas plasma processing apparatus 400 has a substantially cylindrical processing vessel (chamber) 210 made of metal, for example, aluminum whose surface is anodized. The processing vessel 210 is safety grounded.

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

[0065] In order to improve the uniformity of the plasma processing, a conductive focus ring 224 made of, for example, silicon is disposed around the electrostatic chuck 218. A cylindrical inner wall member 226 made of, for example, quartz is provided on the side surfaces of the substrate mounting table 216 and the support table 214.

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

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

[0068] An upper electrode 234 is provided above the substrate mounting table (lower electrode) 216 so as to face the substrate mounting table 216. The space between the upper electrode 234 and the substrate mounting table (lower electrode) 216 becomes a plasma generation space.

[0069] The upper electrode 234 is supported on the upper part of the processing vessel 210 via an insulating shielding member 243. The upper electrode 234 is composed of an electrode plate 236 that forms a surface facing the substrate placement table 216 and has a number of gas discharge holes 237, and an electrode support 238 with a water-cooled structure that detachably supports the electrode plate 236. A gas diffusion chamber 240 is provided inside the electrode support 238, and a number of gas flow holes 241 that communicate with the gas discharge holes 237 extend downward from the gas diffusion chamber 240. A gas inlet 242 that introduces an inert gas into the gas diffusion chamber 240 is formed in the electrode support 238, and a gas pipe 251 that is connected to a gas supply unit 250 described later is connected to the gas inlet 242. The inert gas supplied from the gas supply unit 250 is supplied to the gas diffusion chamber 240, and is supplied to the plasma generation space in the processing vessel 210 through the gas flow holes 241 and the gas discharge holes 237. That is, 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 supply source, a pipe, 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 pipe 251 as described above. The inert gas supplied from the gas supply unit 250 may be a rare gas such as Ar gas or He gas, or N2 gas. Among these, Ar gas is preferable because it has a large atomic number and a large physical effect. Two or more inert gases may be mixed.

[0071] An exhaust port 260 is provided at the bottom of the processing vessel 210, and an exhaust device 264 is connected to the exhaust port 260 via an exhaust pipe 262. The exhaust device 264 has an automatic pressure control valve and a vacuum pump, and is capable of exhausting the inside of the processing vessel 210 and maintaining the inside of the processing vessel 210 at a desired vacuum level by the exhaust device 264. A load / unload port 265 for loading / unloading the substrate W into / from the processing vessel 210 is provided at a sidewall of the processing vessel 210, and the load / unload port 265 is configured to be opened and closed by a gate valve 266.

[0072] A first high frequency power supply 288 for generating plasma is electrically connected to the upper electrode 234. A first matching box 287 is interposed in a power supply 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 placement table (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 box 287 is for matching 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 applying a bias is electrically connected to the substrate mounting table 216, which is the lower electrode. A second matching box 291 is interposed in a power feeder 293 that supplies power from the second high frequency power supply 292 to the substrate mounting table 216. A bias is applied to the substrate W by supplying high frequency power from the second high frequency power supply 292 to the substrate mounting table 216, and ions are attracted to the substrate W. In this way, the bias is applied to the substrate W to attract ions in the plasma, particularly Ar ions, to the substrate, thereby increasing the physical action on the Ru film on the substrate surface. 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 box 291 is for matching the load (plasma) impedance to the impedance on the second high frequency power supply 292 side. The second high frequency power supply 292 is not essential, but is preferably provided in order to increase the physical action on the substrate W.

[0074] In the inert gas plasma processing apparatus 400 thus configured, first, the substrate W is carried into the processing chamber 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 adjustment 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, or further 100 to 130°C.

[0075] Next, after the processing vessel 210 is evacuated to a vacuum, the pressure inside the processing vessel 210 is adjusted to, for example, 100 mTorr to 2 Torr (13.3 to 266.6 Pa) while supplying an inert gas into the processing vessel 210.

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

[0077] After the above plasma processing is performed for a predetermined time, for example, 5 to 300 seconds, the plasma is turned off, the processing vessel 210 is purged with an inert gas, and then the processing vessel 210 is unloaded.

[0078] In this embodiment, the capacitively coupled plasma is used, but other plasma such as inductively coupled plasma or microwave plasma may be used.

[0079] In addition, the inert gas plasma processing apparatus 400 is actually connected to a vacuum transfer chamber maintained at a vacuum, and is incorporated into a system configured such that a substrate is transferred from a substrate storage container arranged in a loading / unloading station to the inert gas plasma processing apparatus 400 by a transfer mechanism in the vacuum transfer chamber via a load lock chamber.

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

[0081] The processing vessel 310 is a cylindrical metal vessel having a substantially sealed structure, and the inside is maintained at normal pressure. A heating plate 320 is provided at the center of the bottom inside the processing vessel 310. A loading / unloading port 311 for loading and unloading the substrate W is formed in the side wall of the processing vessel 310, and the loading / unloading port 311 is opened and closed by a shutter 312. A gas inlet 313 for introducing a reducing gas is formed in the center of the ceiling wall of the processing vessel 310, and a plurality of exhaust ports 314 are formed outside the heating plate 320 in the bottom wall.

[0082] The heating plate 320 supplies a reducing gas into the processing vessel 310, is made of metal, has a substrate W placed on its upper surface and is heated, and has a heater 321 embedded inside. The heater 321 heats the heating plate 320 so that the temperature of the substrate W placed thereon becomes 200 to 430°C, for example, 400°C.

[0083] The gas supply unit 330 supplies a reducing gas into the processing vessel 310 through a pipe 331 and a gas inlet 313. The reducing gas may be a forming gas, H2 gas, formic acid, or the like.

[0084] In the reduction processing apparatus 500 configured as above, first, the substrate W after the plasma processing using the inert gas is carried 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 the heater 321 so that the temperature of the placed substrate W is 200 to 430°C, for example, 400°C.

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

[0086] After the reducing gas is supplied for a predetermined time, the supply of the reducing gas is stopped, and the substrate on the heating plate 320 is carried out from the processing chamber 310 by a transfer mechanism (not shown).

[0087] The reduction processing device 500 configured as a reduction annealing device is actually incorporated into a system configured such that substrates are transported to the reduction processing device 500 by a transport mechanism from a substrate storage container arranged in a carry-in / out station.

[0088] In the above example, the reduction processing apparatus 500 is described as one that performs reduction annealing at normal pressure, but the reduction processing apparatus 500 may be a hydrogen plasma processing apparatus that performs hydrogen plasma processing. Such a hydrogen plasma processing apparatus may have a structure similar to that of the inert gas plasma processing apparatus 400 shown in FIG. 7, and may be one in which the gas supplied from the gas supply unit is H2 gas or H2 gas + inert gas. However, in the case of a hydrogen plasma processing apparatus, a high frequency power supply for bias may not be used. Also, the gas supply unit 250 of the inert gas plasma processing apparatus 400 shown in FIG. 7 may be provided with an H2 gas supply function so that the reduction processing can be performed in the inert gas plasma processing apparatus 400.

[0089] When a reduction annealing apparatus is used as the reduction processing apparatus 500, it is necessary to set the pressure at normal pressure from the inert gas plasma processing apparatus 400 where the vacuum processing is performed. In contrast, when the reduction processing is hydrogen plasma processing, it is a vacuum processing, so that the inert gas plasma processing and the hydrogen plasma processing can be realized in one vacuum system, which is efficient. In addition, by making it possible to perform hydrogen plasma processing in the inert gas plasma processing apparatus 400 (performing the inert gas plasma processing apparatus 400 and the reduction processing apparatus 500 in one apparatus), an even more efficient substrate processing system can be realized.

[0090] [Substrate transport mechanism] The substrate transport mechanisms 600 and 700 transport substrates stored in a substrate storage container 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. The substrate transport mechanisms 600 and 700 preferably transport the substrates in a state in which the substrate storage container is maintained in a non-oxidizing atmosphere such as an inert atmosphere or a reducing atmosphere, so that oxidation of the Ru film formed by electroless plating is suppressed.

[0091] [Control Unit] The control unit 800 controls each component of the substrate processing system 200, i.e., 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 having 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 on a processing recipe stored in, for example, 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 electroless plating apparatus 300, the inert gas plasma processing apparatus 400, and the reduction processing apparatus 500 configured as described above are operated as described above under the control of the control unit 800, thereby realizing one embodiment of the substrate processing method.

[0093] <Experimental Example> Here, the following samples were prepared for the Ru film formed by electroless plating: an as-depo state (sample 1), a sample that was only subjected to reductive annealing after plating (sample 2), and samples that were subjected to Ar plasma treatment and then reductive annealing after plating (samples 3 and 4). The reductive annealing was performed for 10 minutes at 400°C using forming gas (4% H2) as the reducing gas. The Ar plasma treatment was performed under the common conditions of 100% Ar gas, high frequency power (HF) to the top: 1500W, high frequency power (LF) to the bottom: 500W, and time: 100sec, while the pressure and temperature were changed for sample 3 and sample 4. That is, the pressure was 300mTorr and the temperature was 80°C for sample 3, and the pressure was 200mTorr and the temperature was 120°C for sample 4.

[0094] SEM observations showed that in as-depo sample 1, crystal growth had not progressed sufficiently and the film was close to amorphous. In sample 2, which had only been subjected to reduction annealing, crystal growth was observed but numerous cracks were also found. Of the samples that had been treated with Ar plasma, sample 3 had almost no cracks in the film, but slight defects were found in the film, and sample 4 had almost no cracks or defects in the film.

[0095] Measurements of the resistivity of the films revealed that Sample 1 in the as-depo state had a resistivity of 113 μΩ·cm, Sample 2, which had only been subjected to reductive annealing, had a resistivity of 43.7 μΩ·cm, while Samples 3 and 4, which had been treated with Ar plasma, both had low resistivities of 15.1 μΩ·cm.

[0096] From the above results, it was confirmed that a healthy Ru film with low resistance can be obtained by performing Ar plasma treatment on a Ru film formed by electroless plating and then performing reduction treatment.

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

[0098] For example, the electroless plating apparatus in the above embodiment is merely an example, and various other apparatuses may be used. Also, the inert gas plasma processing apparatus in the above embodiment is merely an example, and various other apparatuses may be used. As for the plasma, as described above, it is not limited to capacitively coupled plasma, and other plasmas such as inductively coupled plasma and microwave plasma may be used.

[0099] Furthermore, in the above embodiment, a case has been shown in which a semiconductor substrate (semiconductor wafer) having a semiconductor base is used as the substrate, but the substrate is not limited to a semiconductor wafer, and may be other substrates such as an FPD (flat panel display) substrate, a ceramic substrate, etc. Furthermore, in the above embodiment, a case has been shown in which a Ru film is embedded in a fine via, but the present invention is not limited to this. [Explanation of symbols]

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

Claims

1. forming a Ru film on the substrate by electroless plating; a step of performing a plasma treatment of an inert gas on the substrate on which the Ru film is formed; performing a reduction treatment on the substrate after the treatment with the inert gas plasma; The substrate processing method comprises:

2. 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 onto the substrate, heating the substrate to deposit a plating film that becomes the Ru film, and drying the substrate.

3. 3. The substrate processing method according to claim 2, wherein the substrate is heated to a temperature of 50 to 85.degree.

4. In the treatment with the plasma of the inert gas, the inert gas is Ar gas or N ２ The method of claim 1 comprising a gas.

5. 5. The substrate processing method according to claim 4, wherein the processing with the plasma of the inert gas is performed in a state where 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 a via provided in the insulating film so that the lower layer wiring is exposed at a bottom surface thereof; 6. The substrate processing method according to claim 1, wherein the Ru film grows bottom-up from the lower wiring using the lower wiring as a catalyst.

7. 6. The substrate processing method according to claim 1, wherein the step of reducing the substrate is performed by reduction annealing in which the substrate is heated at normal pressure while a reducing gas is supplied.

8. The reducing gas is a forming gas, H ２ 8. The method of claim 7, wherein the gas is at least one selected from the group consisting of a gas and formic acid.

9. 8. 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.degree.

10. The step of reducing the substrate comprises ２ The substrate processing method according to claim 1 , wherein the substrate is processed by a hydrogen plasma process using a plasma of a gas containing the hydrogen gas.

11. 6. The substrate processing method according to claim 1, wherein the step of performing the treatment using the inert gas plasma is performed at a pressure in the range of 13.3 to 266.6 Pa.

12. 6. The substrate processing method according to claim 1, wherein the step of performing the treatment using the inert gas plasma is performed at a temperature in the range of 70 to 400.degree.

13. 6. The substrate processing method according to claim 1, wherein the time for performing the treatment using the 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; an inert gas plasma processing apparatus for processing the substrate on which the Ru film has been formed by the electroless plating apparatus, using plasma of an inert gas; a reduction treatment device that performs a reduction treatment on the substrate that has been treated by the inert gas plasma treatment device; A substrate processing system comprising:

15. In the inert gas plasma processing apparatus, the inert gas is Ar gas or N ２ The substrate processing system of claim 14 comprising a gas.

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

17. 17. The substrate processing system according to claim 14, wherein the reduction treatment device is a reduction annealing device that heats the substrate at normal pressure while supplying a reduction gas.

18. The reduction treatment device is H ２ 17. The substrate processing system according to claim 14, which is a hydrogen plasma processing apparatus for processing a substrate with plasma of a gas containing the hydrogen gas.

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