Plating method and plating apparatus

Abstract

A plating method according to an embodiment of the present disclosure includes a removal step and a formation step. In the removal step, a potassium hydroxide aqueous solution is brought into contact with a substrate (W) that is exposed on the surface (111) of an insulating film (110) and that has wiring (100) containing ruthenium, and a ruthenium-containing residue (R) affixed to the surface of the substrate (W) is removed. In the formation step, an electroless plating solution is brought into contact with the surface of a substrate (W) from which the residue (R) has been removed, and the wiring (100) is used as a catalyst and an electroless plating film (130) is formed.

Description

Technical Field

[0001] The present disclosure relates to a plating treatment method and a plating treatment apparatus. Background Art

[0002] Conventionally, as a method for forming multilayer wiring on a semiconductor wafer serving as a substrate, there has been known a method of performing electroless plating treatment using wiring exposed from the bottom of a via as a catalyst to fill the inside of the via with the wiring (see Patent Document 1). Prior Art Documents Patent Documents

[0003] Patent Document 1 International Publication No. 2019 / 163531 Summary of the Invention Problems to be Solved by the Invention

[0004] The present disclosure provides a technique capable of satisfactorily forming an electroless plating film using ruthenium-containing wiring as a catalyst. Means for Solving the Problems

[0005] A plating treatment method according to one aspect of the present disclosure includes a removing step and a forming step. In the removing step, a potassium hydroxide aqueous solution is brought into contact with a substrate having ruthenium-containing wiring exposed on a surface of an insulating film, to remove ruthenium-containing residues attached to the surface of the substrate. In the forming step, an electroless plating solution is brought into contact with the surface of the substrate from which the residues have been removed, and an electroless plating film is formed using the wiring as a catalyst. Effects of the Invention

[0006] According to this disclosure, electroless plating films can be successfully formed using wiring containing ruthenium as a catalyst. The effects described herein are not necessarily limited and may include any of the effects described in this disclosure. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows the configuration of a substrate processing apparatus according to an embodiment. [Figure 2] Figure 2 shows the configuration of the plating processing unit according to the embodiment. [Figure 3] Figure 3 is an enlarged cross-sectional view showing the state of the substrate surface before the residue removal treatment according to the embodiment. [Figure 4] Figure 4 is a diagram illustrating the residue removal process according to the embodiment. [Figure 5] Figure 5 is an enlarged cross-sectional view showing the state of the substrate surface after the residue removal treatment according to the embodiment. [Figure 6] Figure 6 is an enlarged cross-sectional view showing the state of the substrate surface after electroless plating according to the embodiment. [Figure 7] Figure 7 shows the relationship between the residue removal solution and the results of the electroless plating process. [Figure 8] Figure 8 is a flowchart showing the processing procedure in the plating process according to the embodiment. [Figure 9] Figure 9 is a flowchart showing the processing procedure in the plating process according to a modified embodiment. [Modes for carrying out the invention]

[0008] The embodiments of the plating method and plating apparatus disclosed herein will be described in detail below with reference to the attached drawings. However, the embodiments described below do not limit this disclosure. Furthermore, it should be noted that the drawings are schematic, and the dimensional relationships and ratios of the elements may differ from reality. Additionally, there may be differences in dimensional relationships and ratios between the drawings themselves.

[0009] Conventionally, a known method for forming multilayer wiring on a semiconductor wafer substrate involves electroless plating using the exposed wiring at the bottom of a via as a catalyst, thereby filling the inside of the via with wiring.

[0010] On the other hand, when ruthenium wiring is exposed from the bottom of a via using a dry etching method, ruthenium-containing residue is scattered and adheres to the surface of the substrate. Since this residue cannot be easily removed by conventional methods, if electroless plating is performed using the ruthenium wiring exposed from the bottom of the via as a catalyst, the residue remaining on the surface also functions as a catalyst.

[0011] Therefore, with conventional technology, the electroless plating film is formed not only inside the via but also in other areas, making it extremely difficult to fill only the inside of the via with the electroless plating film.

[0012] Therefore, there is a need to overcome the aforementioned problems and realize a technology that can successfully form an electroless plating film at a desired location (for example, inside a via) using wiring containing ruthenium as a catalyst.

[0013] <Overview of substrate processing equipment> First, the schematic configuration of the substrate processing apparatus 1 according to the embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing the configuration of the substrate processing apparatus 1 according to the embodiment. In the following, in order to clarify the positional relationships, the X, Y, and Z axes are defined as being orthogonal to each other, and the positive direction of the Z axis is defined as the vertically upward direction.

[0014] As shown in Figure 1, the substrate processing apparatus 1 comprises an input / output station 2 and a processing station 3. The input / output station 2 and the processing station 3 are located adjacent to each other.

[0015] The carry-in / out station 2 includes a carrier mounting table 11 and a transfer unit 12. A plurality of carriers C that accommodate a plurality of substrates, in this embodiment semiconductor wafers (hereinafter also referred to as substrates W), in a horizontal state are mounted on the carrier mounting table 11.

[0016] On the carrier mounting table 11, a plurality of load ports are arranged side by side adjacent to the transfer unit 12, and one carrier C is mounted on each of the plurality of load ports.

[0017] The transfer unit 12 is provided adjacent to the carrier mounting table 11, and includes a substrate transfer device 13 and a transfer unit 14 inside. The substrate transfer device 13 includes a wafer holding mechanism that holds the substrate W. Further, the substrate transfer device 13 is capable of moving in horizontal and vertical directions and rotating about a vertical axis, and transfers the substrate W between the carrier C and the transfer unit 14 using the wafer holding mechanism.

[0018] The processing station 3 is provided adjacent to the transfer unit 12. The processing station 3 includes a transfer unit 15 and a plurality of plating processing units 5. The plurality of plating processing units 5 are arranged side by side on both sides of the transfer unit 15. The configuration of the plating processing unit 5 will be described later.

[0019] The transfer unit 15 includes a substrate transfer device 17 inside. The substrate transfer device 17 includes a wafer holding mechanism that holds the substrate W. Further, the substrate transfer device 17 is capable of moving in horizontal and vertical directions and rotating about a vertical axis, and transfers the substrate W between the transfer unit 14 and the plating processing unit 5 using the wafer holding mechanism.

[0020] Further, the substrate processing apparatus 1 includes a control device 9. The control device 9 is, for example, a computer, and includes a control unit 91 and a storage unit 92. Programs for controlling various processes executed in the substrate processing apparatus 1 are stored in the storage unit 92. The control unit 91 controls the operation of the substrate processing apparatus 1 by reading and executing the program stored in the storage unit 92.

[0021] Furthermore, such a program may have been recorded on a computer-readable storage medium and installed from that storage medium into the storage unit 92 of the control device 9.

[0022] Computer-readable storage media include, for example, hard disks (HDs), flexible disks (FDs), compact discs (CDs), magnetic optical discs (MOs), and memory cards.

[0023] In the substrate processing apparatus 1 configured as described above, first, the substrate transport device 13 of the loading / unloading station 2 takes out the substrate W from the carrier C placed on the carrier mounting table 11 and places the taken out substrate W on the transfer unit 14.

[0024] The substrate W placed on the transfer unit 14 is removed from the transfer unit 14 by the substrate transport device 17 of the processing station 3, transported to the plating processing unit 5, and processed by the plating processing unit 5.

[0025] For example, recesses such as trenches and vias 120 (see Figure 3) are formed on the front surface of the substrate W, and the plating treatment unit 5 fills these recesses with metal using an electroless plating method. The front surface of the substrate W is an example of the surface of the substrate W.

[0026] The substrate W processed by the plating processing unit 5 is removed from the plating processing unit 5 by the substrate transport device 17 and placed on the transfer unit 14. The processed substrate W placed on the transfer unit 14 is then returned to the carrier C on the carrier mounting table 11 by the substrate transport device 13.

[0027] <Overview of the plating process> Next, the general configuration of the plating processing unit 5 will be described with reference to Figure 2. Figure 2 is a diagram showing the configuration of the plating processing unit 5 according to an embodiment. The plating processing unit 5 is configured, for example, as a single-wafer processing unit that processes substrates W one at a time.

[0028] The plating section 5 is configured to perform a solution treatment, including electroless plating. The plating section 5 includes a chamber 51, a substrate holding section 52 positioned inside the chamber 51 to hold the substrate W horizontally, and a plating solution supply section 53 that supplies the plating solution L1 to the front surface (upper surface) of the substrate W held by the substrate holding section 52.

[0029] In this embodiment, the substrate holding portion 52 has a chuck member 521 that vacuum-suctions the back surface (bottom surface) of the substrate W. This chuck member 521 is, for example, a vacuum chuck type chuck member.

[0030] A rotary motor 523 is connected to the substrate holder 52 via a rotary shaft 522. When this 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. Note that no heating source such as a heater is provided inside the substrate holder 52.

[0031] The plating solution supply unit 53 includes a plating solution nozzle 531 that discharges (supplies) the plating solution L1 to 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 is configured to supply the plating solution L1, which has been heated or temperature-controlled to a predetermined temperature, to the plating solution nozzle 531 via the plating solution piping 533.

[0032] The temperature of the plating solution L1 when it is discharged from the plating solution nozzle 531 is, for example, 55°C to 75°C, and more preferably 60°C to 70°C. The plating solution nozzle 531 is held by a nozzle arm 56 and is configured to be movable.

[0033] Plating solution L1 is a plating solution for autocatalytic (reducing) electroless plating. Plating solution L1 contains, for example, metal ions and a reducing agent. The metal ions contained in plating solution L1 include, for example, ruthenium (Ru) ions, cobalt (Co) ions, nickel (Ni) ions, tungsten (W) ions, copper (Cu) ions, palladium (Pd) ions, and gold (Au) ions.

[0034] Furthermore, the reducing agents contained in the plating solution L1 include hypophosphorous acid, dimethylamine borane, and glyoxylic acid. Examples of plating layers formed by the plating process using the plating solution L1 include Ru, CoWB, CoB, CoWP, CoWBP, NiWB, NiB, NiWP, NiWBP, Cu, and Pd.

[0035] The plating section 5 further includes a removal liquid supply unit 54 that supplies a residue removal liquid L2 to the front 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 front surface of the substrate W.

[0036] The removal liquid supply unit 54 supplies residue removal liquid L2 to the substrate W, which is held and rotated by the substrate holding unit 52, and removes the residue R (see Figure 3) adhering to the front surface of the substrate W. This removal liquid supply unit 54 includes a removal liquid nozzle 541 that discharges the residue removal liquid L2 to the substrate W held by the substrate holding unit 52, and a removal liquid supply source 542 that supplies the residue removal liquid L2 to the removal liquid nozzle 541.

[0037] Of these, the removal liquid supply source 542 is configured to supply the residue removal liquid L2, which has been heated or temperature-controlled to a predetermined temperature, to the removal liquid nozzle 541 via the cleaning liquid piping 543, as will be described later. The removal liquid nozzle 541 is held by the nozzle arm 56 and is movable together with the plating liquid nozzle 531.

[0038] As the residue removal solution L2, an aqueous solution of potassium hydroxide (KOH) adjusted to a given concentration is used. That is, the residue removal solution L2 according to this embodiment consists only of potassium hydroxide, water, and unavoidable impurities.

[0039] The rinse liquid supply unit 55 includes a rinse liquid nozzle 551 that discharges rinse liquid L3 onto the substrate W held by the substrate holding unit 52, and a rinse liquid supply source 552 that supplies rinse liquid L3 to the rinse liquid nozzle 551.

[0040] Of these, the rinse solution nozzle 551 is held by the nozzle arm 56 and is movable together with the plating solution nozzle 531 and the removal solution nozzle 541. The rinse solution supply source 552 is configured to supply the rinse solution L3 to the rinse solution nozzle 551 via the rinse solution piping 553. For the rinse solution L3, for example, DIW can be used.

[0041] A nozzle arm 56, which holds the plating solution nozzle 531, removal solution nozzle 541, and rinsing solution nozzle 551 described above, is connected to a nozzle moving mechanism (not shown). This nozzle moving mechanism moves the nozzle arm 56 in the horizontal and vertical directions.

[0042] More specifically, the nozzle arm 56 is movable between a discharge position where it discharges the processing liquid (plating solution L1, residue removal solution L2, or rinsing solution L3) onto the substrate W, and a retracted position where it is moved away from the discharge position, via a nozzle movement mechanism.

[0043] The discharge position is not particularly limited as long as the processing liquid can be supplied to any position on the front surface of the substrate W. For example, it is preferable to set the discharge position to one that can supply the processing liquid to the center of the substrate W.

[0044] The discharge position of the nozzle arm 56 may differ depending on whether plating solution L1 is supplied to the substrate W, residue removal solution L2 is supplied, or rinsing solution L3 is supplied. The retracted position is a position within the chamber 51 that does not overlap with the substrate W when viewed from above, and is away from the discharge position. When the nozzle arm 56 is positioned in the retracted position, interference between the moving cover 6 and the nozzle arm 56 is avoided.

[0045] A cup 571 is provided around the substrate holder 52. This cup 571 is formed in a ring shape when viewed from above, and when the substrate W rotates, it catches the processing liquid that splashes from the substrate W and guides it to the drain duct 581.

[0046] An atmosphere-blocking cover 572 is provided on the outer circumference of the cup 571 to suppress the diffusion of the surrounding atmosphere of the substrate W into the chamber 51. This atmosphere-blocking cover 572 is formed in a cylindrical shape that extends vertically, with an open upper end. A lid 6, which will be described later, can be inserted into the atmosphere-blocking cover 572 from above.

[0047] In this embodiment, the substrate W held in the substrate holding portion 52 is covered by a cover 6. This cover 6 has a top portion 61 and a side wall portion 62 extending downward from the top portion 61.

[0048] The ceiling section 61 includes a first ceiling plate 611 and a second ceiling plate 612 provided on the first ceiling plate 611. A heater 63 is interposed between the first ceiling plate 611 and the second ceiling plate 612. The first ceiling plate 611 and the second ceiling plate 612 are configured to seal the heater 63 and prevent the heater 63 from coming into contact with the processing liquid such as the plating solution L1.

[0049] More specifically, a seal ring 613 is provided on the outer circumference of the heater 63, and the heater 63 is sealed by this seal ring 613. The first ceiling plate 611 and the second ceiling plate 612 preferably have corrosion resistance to processing liquids such as plating solution L1, and may be made of, 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®.

[0050] A lid moving mechanism 7 is connected to the lid 6 via a lid arm 71. The lid moving mechanism 7 moves the lid 6 horizontally and vertically. More specifically, 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.

[0051] The slewing motor 72 is mounted on a support plate 74 that is movable vertically relative to the cylinder 73. Instead of the cylinder 73, an actuator (not shown) including a motor and a ball screw may be used.

[0052] 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 part 52 and a retracted position, which is a position retracted from the upper position. The upper position is a position that is relatively far away from the substrate W held by the substrate holding part 52 and overlaps with the substrate W when viewed from above.

[0053] The retracted position is a position within the chamber 51 that does not overlap with the substrate W when viewed from above. When the lid 6 is positioned in the retracted position, interference between the moving nozzle arm 56 and the lid 6 is avoided. The rotation axis of the slewing motor 72 extends in the vertical direction, and the lid 6 is capable of slewing horizontally between the upper position and the retracted position.

[0054] The cylinder 73 of the lid moving mechanism 7 moves the lid 6 vertically to adjust the distance between the substrate W to which the plating solution L1 is supplied and the first ceiling plate 611 of the ceiling portion 61. More specifically, the cylinder 73 positions the lid 6 in a lower position (shown by a solid line in Figure 2) and an upper position (shown by a dashed line in Figure 2).

[0055] In this embodiment, when the heater 63 is driven and the lid 6 is positioned in the lower position described above, the substrate holding portion 52 or the plating solution L1 on the substrate W is heated.

[0056] 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 support portions 65. Specifically, a plurality of support portions 65 are provided on the second ceiling plate 612, projecting upward from the upper surface of the second ceiling plate 612, and the lid cover 64 is placed on these support portions 65.

[0057] The lid cover 64 is movable horizontally and vertically together with the lid 6. Furthermore, it is preferable that the lid cover 64 has higher thermal insulation properties than the ceiling portion 61 and the side wall portion 62 in order to suppress heat from escaping from inside the lid 6 to the surroundings. For example, it is preferable that the lid cover 64 is made of a resin material, and it is even more preferable that the resin material has heat resistance.

[0058] In this embodiment, a lid 6 equipped with a heater 63 and a lid cover 64 are integrally provided, and a cover unit 10 that covers the substrate holding portion 52 or the substrate W when positioned in a lower position is formed by these lid 6 and lid cover 64.

[0059] 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), and the supplied air flows toward the exhaust pipe 81.

[0060] A downflow is formed around the lid 6, allowing the air to flow downwards. The gas vaporized from the processing solution, such as the plating solution L1, flows towards the exhaust pipe 81 due to this downflow. In this way, the gas vaporized from the processing solution is prevented from rising and diffusing into the chamber 51.

[0061] The gas supplied from the fan filter unit 59 described above is discharged by the exhaust mechanism 8.

[0062] <Details of the plating process> Next, the details of the plating process according to the embodiment will be explained with reference to Figures 3 to 7. Figure 3 is an enlarged cross-sectional view showing the state of the substrate W surface before the residue removal process according to the embodiment.

[0063] Note that elements not shown have already been formed on the substrate W shown in Figure 3. Then, in the wiring formation process after the formation of such elements (so-called BEOL (Back End of Line)), various processes for filling the vias 120 formed in the insulating film 110 on the wiring 100 with metal wiring will be described below.

[0064] As shown in Figure 3, metal wiring 100 is formed on the substrate W, and an insulating film 110 is provided on the wiring 100. In this embodiment, for example, the entire insulating film 110 is composed of a silicon oxide film.

[0065] The wiring 100 according to the embodiment is composed of an element that does not diffuse inside the insulating film 110. The wiring 100 is composed of a conductive material containing, for example, ruthenium.

[0066] Furthermore, vias 120 are formed on the substrate W at a given position in the insulating film 110. Such vias 120 are an example of recesses and are formed to penetrate from the surface 111 of the insulating film 110 to the wiring 100. The vias 120 have a side surface 121 and a bottom surface 122 in which the wiring 100 is exposed.

[0067] As a method for forming vias 120 in the insulating film 110 of the substrate W, any conventionally known method can be appropriately adopted. Specifically, for example, a general-purpose technique using fluorine-based or chlorine-based gas can be applied as a dry etching technique.

[0068] In particular, as a method for forming vias 120 with a large aspect ratio (ratio of depth to diameter), the ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching) technique, which enables high-speed deep etching, can be employed.

[0069] For example, the so-called Bosch process, which involves repeatedly performing an etching step using sulfur hexafluoride (SF6) and a protection step using a gas such as C4F8, can be suitably employed.

[0070] In this embodiment, as shown in Figure 3, during the process of forming the via 120, the residue R that is scattered when the bottom surface 122 of the via 120 is exposed adheres to the surface 111 of the insulating film 110 and the side surface 121 of the via 120. This residue R, like the wiring 100, contains ruthenium.

[0071] Furthermore, this ruthenium-containing residue R is extremely difficult to remove with conventional pre-washing solutions (for example, organic acids such as dicarboxylic acids or tricarboxylic acids).

[0072] Therefore, in conventional technology, when electroless plating is performed using the wiring 100 exposed from the bottom surface 122 of the via 120 as a catalyst, the residue R remaining on the surface 111 of the insulating film 110 and the side surface 121 of the via 120 also functions as a catalyst.

[0073] As a result, in conventional technology, an electroless plating film is formed on the surface 111 of the insulating film 110 and the side surface 121 of the via 120, making it extremely difficult to fill only the inside of the via 120 with an electroless plating film.

[0074] Therefore, in this embodiment, a residue removal treatment is performed to remove residue R as a pretreatment for electroless plating. Figure 4 is a diagram illustrating the residue removal treatment according to this embodiment.

[0075] As shown in Figure 4, in the plating process according to this embodiment, first, the control unit 91 (see Figure 1) controls the removal liquid supply unit 54 to discharge the residue removal liquid L2 from the removal liquid nozzle 541 onto the front surface of the substrate W, and bring the residue removal liquid L2 into contact with the front surface of the substrate W.

[0076] As a result, the control unit 91 uses the residue removal liquid L2 to perform a process to remove the residue R (see Figure 3) adhering to the front surface of the substrate W.

[0077] This residue removal process removes the residue R (see Figure 3) adhering to the front surface of the substrate W (for example, the surface 111 of the insulating film 110 or the side surface 121 of the via 120), as shown in Figure 5. Figure 5 is an enlarged cross-sectional view showing the state of the substrate W surface after the residue removal process according to the embodiment.

[0078] Furthermore, in this embodiment, since the residue removal solution L2 is an aqueous potassium hydroxide solution, the outermost surface of the insulating film 110 can be efficiently etched, and the residue R adhering to this outermost surface can be efficiently lifted off.

[0079] Furthermore, in this embodiment, since the residue removal solution L2 is an alkaline potassium hydroxide aqueous solution, the front surface of the substrate W becomes negatively charged. And since the residue R containing metal is also negatively charged, in this embodiment, an electrostatic repulsion force acts between the front surface of the substrate W and the residue R, thereby suppressing the re-adhesion of the residue R to the front surface of the substrate W.

[0080] Furthermore, in this embodiment, since the residue removal solution L2 is an aqueous potassium hydroxide solution, the ruthenium wiring 100 exposed on the bottom surface 122 of the via 120 is hardly etched. As a result, the state of the wiring 100 exposed on the bottom surface 122 of the via 120 hardly changes, and the wiring 100 functions well as a catalyst in the subsequent electroless plating process.

[0081] Following the residue removal process described above, in this embodiment, an electroless plating process is performed. In this electroless plating process, for example, the control unit 91 (see Figure 1) controls the plating solution supply unit 53 (see Figure 2) to discharge the plating solution L1 (see Figure 2) from the plating solution nozzle 531 (see Figure 2) onto the front surface of the substrate W, and bring the plating solution L1 into contact with the front surface of the substrate W.

[0082] The plating solution L1 discharged onto the surface of the substrate W remains on the surface of the substrate W due to surface tension, and the plating solution L1 is deposited on the surface of the substrate W, forming a layer of plating solution L1 (a so-called paddle).

[0083] As a result, as shown in Figure 6, the wiring 100 exposed on the bottom surface 122 of the via 120 acts as a catalyst, forming an electroless plating film 130 that rises from the bottom surface 122 of the via 120, and filling the inside of the via 120 with the electroless plating film 130. Figure 6 is an enlarged cross-sectional view showing the state of the substrate W surface after the electroless plating treatment according to the embodiment.

[0084] As described above, in this embodiment, by performing a residue removal treatment using an aqueous potassium hydroxide solution as a pretreatment for electroless plating, the ruthenium-containing wiring 100 can be used as a catalyst to form a good electroless plating film 130.

[0085] Figure 7 shows the relationship between the residue removal solution L2 and the results of the electroless plating treatment. Note that the results in Figure 7 are experimental results when a ruthenium film was formed as the electroless plating film 130.

[0086] As shown in Figure 7, when an aqueous potassium hydroxide solution was used as the residue removal solution L2, the residue R was effectively removed, and the electroless plating film 130 was formed well only on the vias 120 (rating A).

[0087] On the other hand, when alkaline TMAH (tetramethylammonium hydroxide) was used as the residue removal solution L2, the removal of residue R was insufficient, and a certain amount of electroless plating film 130 was formed not only on the vias 120 but also on the surface 111 of the insulating film 110 (evaluation C).

[0088] Furthermore, when acidic DHF (dilute hydrofluoric acid) is used as the residue removal solution L2, the front surface of the substrate W becomes positively charged, causing the lifted residue R to easily reattach to the front surface of the substrate W due to electrostatic attraction. As a result, many electroless plating films 130 are formed not only on the vias 120 but also on the surface 111 of the insulating film 110 (D rating).

[0089] In this embodiment, the concentration of the potassium hydroxide aqueous solution used in the residue removal solution L2 during the residue removal process may be 1 (wt%) to 5 (wt%). This makes it possible to remove the residue R adhering to the front surface of the substrate W in a relatively short time without significantly changing the shape of the vias 120.

[0090] Furthermore, in the embodiment, potassium hydroxide aqueous solutions of different concentrations may be used consecutively in the residue removal process. For example, in the embodiment, the residue R is first roughly removed with a potassium hydroxide aqueous solution of a first concentration (e.g., about 30 wt%). Subsequently, the residue R may be precisely removed with a potassium hydroxide aqueous solution of a second concentration lower than the first concentration (e.g., about 1 wt% to 5 wt%).

[0091] This makes it possible to remove the residue R adhering to the front surface of the substrate W in a relatively short time without significantly changing the shape of the via 120. In this disclosure, the residue R may be removed first with a low-concentration potassium hydroxide aqueous solution, and then with a high-concentration potassium hydroxide aqueous solution.

[0092] Furthermore, in this embodiment, the temperature of the potassium hydroxide aqueous solution used in the residue removal solution L2 during the residue removal process may be 25°C or higher. This makes it possible to remove the residue R adhering to the front surface of the substrate W in a relatively short time without significantly changing the shape of the vias 120.

[0093] Furthermore, in this embodiment, an electroless plating film 130 containing ruthenium may be formed during the electroless plating process. This allows for the successful formation of a low-resistance electroless plating film 130 on the substrate W.

[0094] In this disclosure, the electroless plating film 130 is not limited to containing ruthenium, but may also contain cobalt, nickel, tungsten, or palladium. Furthermore, if the electroless plating film 130 contains cobalt and tungsten, it is preferable that the electroless plating film 130 contains 1 (at%) to 20 (at%) of tungsten, with the remainder being cobalt and unavoidable impurities.

[0095] This effectively suppresses the diffusion of the electroless plating film 130 filling the inside of the via 120 into the inside of the insulating film 110.

[0096] In this embodiment, the wiring 100 is exposed on the bottom surface of a recess such as a via 120 formed in the insulating film 110, and the inside of such a recess may be filled with an electroless plating film 130. This makes it possible to form via wiring that does not require a barrier layer and has low resistance well inside a recess formed in the insulating film 110.

[0097] In the above embodiment, an example was shown in which an electroless plating film 130 is formed on the front surface of the substrate W using the ruthenium wiring 100 exposed on the bottom surface 122 of the via 120 as a catalyst. However, this disclosure is not limited to such an example.

[0098] For example, before forming the electroless plating film 130 on the substrate W using the ruthenium wiring 100 formed on the surface 111 of the insulating film 110 as a catalyst, a residue removal treatment using an aqueous potassium hydroxide solution may be performed. This also allows for the successful formation of an electroless plating film using the ruthenium-containing wiring 100 as a catalyst.

[0099] Furthermore, although the above embodiment shows an example of applying the technology of this disclosure to a plating processing unit 5 configured as a single-wafer processing unit that processes substrates W one by one, this disclosure is not limited to such an example.

[0100] For example, in a batch-type processing unit that processes multiple substrates W by immersing them together in a processing tank, the residue R may be removed from the multiple substrates W by immersing them in a residue removal solution L2 of potassium hydroxide aqueous solution before electroless plating.

[0101] The plating apparatus (substrate apparatus 1) according to the embodiment comprises a substrate holding unit 52, a removal solution supply unit 54, a plating solution supply unit 53, and a control unit 91. The substrate holding unit 52 holds the substrate W. The removal solution supply unit 54 supplies an aqueous potassium hydroxide solution (residue removal solution L2) to the substrate W held by the substrate holding unit 52. The plating solution supply unit 53 supplies an electroless plating solution (plating solution L1) to the substrate W held by the substrate holding unit 52. The control unit 91 controls each unit. The control unit 91 also contacts the substrate W, which has wiring 100 containing ruthenium exposed on the surface 111 of the insulating film 110, with the aqueous potassium hydroxide solution (residue removal solution L2) to remove the ruthenium-containing residue R adhering to the surface of the substrate W. The control unit 91 also contacts the surface of the substrate W from which the residue R has been removed with the electroless plating solution (plating solution L1) to form an electroless plating film 130 using the wiring 100 as a catalyst. This allows for the smooth formation of an electroless plating film 130 using the ruthenium-containing wiring 100 as a catalyst.

[0102] <Details of the plating process> Next, with reference to Figures 8 and 9, the details of the plating process performed by the substrate processing apparatus 1 according to the embodiment and modified examples will be described. Figure 8 is a flowchart showing the processing procedure in the plating process according to the embodiment.

[0103] First, the control unit 91 controls the substrate transport devices 13 and 17 to transport the substrate W from the carrier C into the plating processing unit 5, and prepares the substrate W by holding it in the substrate holding unit 52 (step S101).

[0104] Next, the control unit 91 performs a residue removal process on the substrate W (step S102). In this case, first, the rotary motor 523 is driven and the substrate W rotates at a predetermined rotational speed. Subsequently, the nozzle arm 57, which was positioned in the retracted position (the position shown by the solid line in Figure 2), moves to the discharge position above the center of the substrate W.

[0105] Next, the residue removal liquid L2 is supplied to the rotating substrate W from the removal liquid nozzle 541, and the residue R adhering to the front surface of the substrate W is removed. The residue removal liquid L2 supplied to the substrate W is discharged into the drain duct 581.

[0106] In the residue removal treatment according to the embodiment, for example, the concentration of the potassium hydroxide aqueous solution is often 1 wt% to 30 wt%, and preferably 1 wt% to 5 wt%. The temperature of the potassium hydroxide aqueous solution is often 25°C to 80°C, and preferably 25°C to 60°C. The processing time for the residue removal treatment is preferably 1 to 10 minutes.

[0107] Next, the control unit 91 performs a rinsing treatment on the substrate W (step S103). In this case, rinsing liquid L3 is supplied to the rotating substrate W from the rinsing liquid nozzle 551, and the front surface of the substrate W is rinsed. This washes away any remaining residue removal liquid L2 on the substrate W. The rinsing liquid L3 supplied to the substrate W is discharged into the drain duct 581.

[0108] Next, the control unit 91 performs electroless plating on the substrate W (step S104). In this case, the plating solution L1 is supplied from the plating solution nozzle 531 to the substrate W, which is rotating at 100 rpm or less, and a paddle of the plating solution L1 is formed on the front surface of the substrate W. As a result, the wiring 100 exposed from the bottom surface 122 of the via 120 formed in the insulating film 110 acts as a catalyst, and an electroless plating film 130 is formed inside the via 120.

[0109] Next, the control unit 91 covers the substrate W with the cover 6 and operates the heater 63 to heat the paddle of the plating solution L1 formed on the front surface of the substrate W (step S105). This promotes the formation of the electroless plating film 130.

[0110] Next, the control unit 91 performs a rinsing treatment on the substrate W (step S106). In this case, first, the cover 6 is moved away from above the substrate W. Subsequently, the rotary motor 523 is driven and the substrate W rotates at a predetermined rotational speed.

[0111] Then, rinsing liquid L3 is supplied to the rotating substrate W from the rinsing liquid nozzle 551, and the front surface of the substrate W is rinsed. This washes away any remaining plating solution L1 on the substrate W. The rinsing liquid L3 supplied to the substrate W is discharged into the drain duct 581.

[0112] Next, the rinsed substrate W is dried (step S107). In this case, for example, the rotation speed of the substrate W is increased compared to the rotation speed during the rinsing process (step S106), causing the substrate W to rotate at high speed. This shakes off any remaining rinse liquid L3 on the substrate W, drying the substrate W.

[0113] Once the drying process is complete, the substrate W is removed from the plating treatment area 5 by the substrate transport device 17 and transported to the transfer area 14. The substrate W transported to the transfer area 14 is then removed from the transfer area 14 by the substrate transport device 13 and placed in the carrier C. This completes the series of plating processes for one substrate W.

[0114] Figure 9 is a flowchart showing the processing procedure in a plating process according to a modified embodiment. First, the control unit 91 controls the substrate transport devices 13 and 17 to transport the substrate W from the carrier C into the plating processing unit 5, and prepares the substrate W by holding the substrate W in the substrate holding unit 52 (step S201).

[0115] Next, the control unit 91 performs a first removal process on the substrate W (step S202). In this case, first, the rotary motor 523 is driven and the substrate W rotates at a predetermined rotational speed. Subsequently, the nozzle arm 57, which was positioned in the retracted position (the position shown by the solid line in Figure 2), moves to the discharge position above the center of the substrate W.

[0116] Next, the residue removal liquid L2 is supplied to the rotating substrate W from the removal liquid nozzle 541, and the residue R adhering to the front surface of the substrate W is removed. The residue removal liquid L2 supplied to the substrate W is discharged into the drain duct 581.

[0117] In the modified first removal treatment (step S202), for example, the concentration of the potassium hydroxide aqueous solution is a first concentration (for example, 30 (wt%)).

[0118] Next, the control unit 91 performs a second removal process on the substrate W (step S203). In this case, the residue removal liquid L2 is supplied to the rotating substrate W from the removal liquid nozzle 541, and the residue R adhering to the front surface of the substrate W is removed. The residue removal liquid L2 supplied to the substrate W is discharged into the drain duct 581.

[0119] In the modified second removal treatment (step S203), for example, the concentration of the potassium hydroxide aqueous solution is a second concentration lower than the first concentration described above (for example, 1 (wt%) to 5 (wt%)).

[0120] Next, the control unit 91 performs a rinsing treatment on the substrate W (step S204). Since this rinsing treatment is the same as the treatment in step S103 described above, a detailed explanation will be omitted.

[0121] Next, the control unit 91 performs an electroless plating process on the substrate W (step S205). Since this electroless plating process is the same as the process in step S104 described above, a detailed explanation is omitted.

[0122] Next, the control unit 91 covers the substrate W with the cover 6 and operates the heater 63 to heat the paddle of the plating solution L1 formed on the front surface of the substrate W (step S206). This promotes the formation of the electroless plating film 130.

[0123] Next, the control unit 91 performs a rinsing treatment on the substrate W (step S207). Since this rinsing treatment is the same as the treatment in step S106 described above, a detailed explanation is omitted.

[0124] Next, the rinsed substrate W is dried (step S208). This drying process is the same as the process in step S107 described above, so a detailed explanation is omitted. This completes the series of plating processes according to the modified example.

[0125] The plating method according to the embodiment includes a removal step (steps S102, S202, S203) and a forming step (steps S104, S205). In the removal step (steps S102, S202, S203), an aqueous potassium hydroxide solution is brought into contact with a substrate W having wiring 100 containing ruthenium that is exposed on the surface 111 of the insulating film 110, to remove the ruthenium-containing residue R adhering to the surface of the substrate W. In the forming step (steps S104, S205), an electroless plating solution (plating solution L1) is brought into contact with the surface of the substrate W from which the residue R has been removed, to form an electroless plating film 130 using the wiring 100 as a catalyst. This makes it possible to form an electroless plating film 130 well using the ruthenium-containing wiring 100 as a catalyst.

[0126] Furthermore, in the plating method according to the embodiment, the removal step includes a first removal step (step S202) and a second removal step (step S203). The first removal step (step S202) involves bringing a potassium hydroxide aqueous solution having a first concentration into contact with the surface of the substrate W. The second removal step (step S203) involves bringing a potassium hydroxide aqueous solution having a second concentration different from the first concentration into contact with the surface of the substrate W after the first removal step (step S202). This makes it possible to remove the residue R adhering to the front surface of the substrate W in a relatively short time without significantly changing the shape of the vias 120.

[0127] Furthermore, in the plating method according to the embodiment, the first concentration is higher than the second concentration. This makes it possible to remove the residue R adhering to the front surface of the substrate W in a relatively short time without significantly changing the shape of the vias 120.

[0128] Furthermore, in the plating method according to the embodiment, the concentration of the potassium hydroxide aqueous solution in the removal step (step S102) is 1 (wt%) to 5 (wt%). This makes it possible to remove the residue R adhering to the front surface of the substrate W in a relatively short time without significantly changing the shape of the vias 120.

[0129] Furthermore, in the plating method according to the embodiment, the temperature of the potassium hydroxide aqueous solution is 25°C or higher in the removal step (steps S102, S202, S203). This makes it possible to remove the residue R adhering to the front surface of the substrate W in a relatively short time without significantly changing the shape of the vias 120.

[0130] Furthermore, in the plating method according to the embodiment, the wiring 100 is exposed on the bottom surface of the recess formed in the insulating film 110. This makes it possible to form via wiring that does not require a barrier layer and has low resistance well inside the recess formed in the insulating film 110.

[0131] Furthermore, in the plating method according to the embodiment, the forming step (steps S104 and S205) involves filling the inside of the recess with an electroless plating film 130. This makes it possible to form via wiring that does not require a barrier layer and has low resistance well inside the recess formed in the insulating film 110.

[0132] Furthermore, in the plating method according to the embodiment, the forming step (steps S104 and S205) forms an electroless plating film 130 containing ruthenium. This makes it possible to form a low-resistance electroless plating film 130 well on the substrate W.

[0133] While embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from its spirit.

[0134] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0135] 1. Substrate processing equipment (an example of plating processing equipment) 5 Plating Processing Section 52 Board holding part 53 Plating solution supply unit 54 Removal liquid supply section 91 Control Unit 100 Wiring 110 Insulating Film 111 Surface L1 Plating solution (an example of an electroless plating solution) L2 Residue removal liquid W board R residue

Claims

1. A step of removing ruthenium-containing residue adhering to the surface of a substrate having wiring exposed on the surface of an insulating film and containing ruthenium, by contacting an aqueous potassium hydroxide solution with the substrate. The process involves bringing an electroless plating solution into contact with the surface of the substrate from which the residue has been removed, and forming an electroless plating film using the wiring as a catalyst. A plating method that includes [a specific type of plating].

2. The aforementioned removal process is: A first removal step involves bringing an aqueous potassium hydroxide solution having a first concentration into contact with the surface of the substrate, The process includes, after the first removal step, a second removal step in which an aqueous potassium hydroxide solution having a second concentration different from the first concentration is brought into contact with the surface of the substrate. The plating method according to claim 1.

3. The first concentration is higher than the second concentration. The plating method according to claim 2.

4. In the removal step described above, the concentration of the potassium hydroxide aqueous solution is 1 wt% to 5 wt%. A plating method according to any one of claims 1 to 3.

5. In the removal process described above, the temperature of the potassium hydroxide aqueous solution is 25°C or higher. A plating method according to any one of claims 1 to 3.

6. The wiring is exposed on the bottom surface of the recess formed in the insulating film. A plating method according to any one of claims 1 to 3.

7. The above forming step involves filling the inside of the recess with an electroless plating film. The plating method according to claim 6.

8. The above-mentioned step involves forming an electroless plating film containing ruthenium. A plating method according to any one of claims 1 to 3.

9. A substrate holding section that holds the substrate, A removal liquid supply unit that supplies an aqueous potassium hydroxide solution to the substrate held by the substrate holding unit, A plating solution supply unit that supplies an electroless plating solution to the substrate held by the substrate holding unit, A control unit that controls each part, Equipped with, The control unit, The potassium hydroxide aqueous solution is brought into contact with the substrate having wiring exposed on the surface of the insulating film and containing ruthenium, to remove the ruthenium-containing residue adhering to the surface of the substrate. The electroless plating solution is brought into contact with the surface of the substrate from which the residue has been removed, and the wiring is used as a catalyst to form an electroless plating film. Plating equipment.

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