Plating method and plating apparatus

Abstract

A plating method according to one embodiment of the present disclosure includes a preparation step, a first plating step, and a second plating step. The preparation step involves preparing a substrate (W) having a cobalt or cobalt alloy seed layer (132) formed in a recessed section. The first plating step involves performing replacement plating in which a surface layer of the seed layer (132) is replaced with copper by using a first plating solution (L1) containing copper ions on the substrate (W). The second plating step involves subjecting the recessed section to a reduction plating by using a second plating solution (L2) containing copper ions and a reducing agent on the substrate (W) after the first plating step.

Description

[Technical field]

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

[0002] Conventionally, a known method for forming multilayer wiring on a semiconductor wafer substrate involves performing an electroless plating process using a copper seed layer formed inside a via as a catalyst to fill the inside of the via with copper wiring (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-102448 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can effectively fill the inside of a via with copper wiring. [Means for solving the problem]

[0005] A plating method according to one embodiment of the present disclosure includes a preparation step, a first plating step, and a second plating step. The preparation step is to prepare a substrate having a seed layer of cobalt or a cobalt alloy formed in a recess. The first plating step is to perform a substitution plating process on the substrate using a first plating solution containing copper ions to substitute a surface layer of the seed layer with copper. The second plating step is to perform a reduction plating process on the recess after the first plating step using a second plating solution containing copper ions and a reducing agent. Effect of the Invention

[0006] According to the present disclosure, the inside of the via can be satisfactorily filled with copper wiring. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a configuration of a substrate processing apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the configuration of the plating processing unit according to the embodiment. [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing the state of the substrate surface before the first plating treatment according to the embodiment. [Figure 4] FIG. 4 is a diagram for explaining the first plating treatment according to the embodiment. [Diagram 5] FIG. 5 is an enlarged cross-sectional view showing the state of the substrate surface after the first plating treatment according to the embodiment. [Figure 6] FIG. 6 is a view for explaining the second plating treatment according to the embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing the state of the substrate surface after the second plating treatment according to the embodiment. [Figure 8] FIG. 8 is a diagram for explaining the first plating process according to a modified example of the embodiment. [Figure 9] FIG. 9 is a diagram for explaining the second plating treatment according to the modified example of the embodiment. [Figure 10] FIG. 10 is a diagram for explaining the second plating treatment according to another modified example of the embodiment. [Figure 11] FIG. 11 is a flowchart showing a processing procedure in the plating process according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, with reference to the attached drawings, an embodiment of the plating method and plating apparatus disclosed in the present application will be described in detail. Note that the present disclosure is not limited to the following embodiment. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from the reality. Furthermore, the drawings may include parts with different dimensional relationships and ratios.

[0009] Conventionally, a known method for forming multilayer wiring on a semiconductor wafer as a substrate is to perform electroless plating using a copper seed layer formed inside a via as a catalyst, thereby filling the inside of the via with copper wiring.

[0010] On the other hand, since the copper seed layer can only be formed by the PVD (Physical Vapor Deposition) method, when the inner diameter of the via becomes smaller due to the recent trend toward finer multilayer wiring, it may not be possible to form a homogeneous copper seed layer inside the via.

[0011] Furthermore, due to the formation of an inhomogeneous copper seed layer inside the via, there is a risk that the inside of the via cannot be filled satisfactorily with copper wiring.

[0012] Therefore, there is a need to realize a technology that can overcome the above-mentioned problems and satisfactorily fill the inside of a via with copper wiring.

[0013] <Outline of the substrate processing system> First, a schematic configuration of a substrate processing apparatus 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the configuration of the substrate processing apparatus 1 according to an embodiment. The substrate processing apparatus 1 is an example of a plating processing apparatus.

[0014] In the following description, in order to clarify the positional relationships, an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other are defined, and the positive direction of the Z-axis is defined as the vertically upward direction.

[0015] 1, the substrate processing apparatus 1 includes a loading / unloading station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are provided adjacent to each other.

[0016] The loading / unloading station 2 includes a carrier mounting table 11 and a transport section 12. On the carrier mounting table 11, a plurality of carriers C are mounted, each of which horizontally accommodates a plurality of substrates, in this embodiment, semiconductor wafers (hereinafter also referred to as substrates W).

[0017] A plurality of load ports are arranged on the carrier placement table 11 adjacent to the transfer section 12, and one carrier C is placed on each of the plurality of load ports.

[0018] The transfer section 12 is provided adjacent to the carrier mounting table 11, and includes therein a substrate transfer device 13 and a transfer section 14. The substrate transfer device 13 includes a wafer holding mechanism that holds the substrate W. The substrate transfer device 13 is capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transfers the substrate W between the carrier C and the transfer section 14 using the wafer holding mechanism.

[0019] The processing station 3 is provided adjacent to the transport section 12. The processing station 3 includes a transport section 15 and a plurality of plating sections 5. The plurality of plating sections 5 are arranged side by side on both sides of the transport section 15. The configuration of the plating sections 5 will be described later.

[0020] The transfer section 15 includes a substrate transfer device 17 therein. The substrate transfer device 17 includes a wafer holding mechanism that holds the substrate W. The substrate transfer device 17 is capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transfers the substrate W between the delivery section 14 and the plating processing section 5 using the wafer holding mechanism.

[0021] The substrate processing apparatus 1 also 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. The storage unit 92 stores programs for controlling various processes executed in the substrate processing apparatus 1. The control unit 91 controls the operation of the substrate processing apparatus 1 by reading out and executing the programs stored in the storage unit 92.

[0022] Incidentally, such a program may be recorded in a computer-readable storage medium and installed in the storage unit 92 of the control device 9 from the storage medium.

[0023] Examples of computer-readable storage media include hard disks (HD), flexible disks (FD), compact disks (CD), magnet optical disks (MO), and memory cards.

[0024] In the substrate processing apparatus 1 configured as described above, first, the substrate transport device 13 in the loading / unloading station 2 removes the substrate W from the carrier C placed on the carrier placement table 11, and places the removed substrate W on the transfer section 14.

[0025] The substrate W placed on the transfer section 14 is removed from the transfer section 14 by the substrate transport device 17 of the processing station 3, transported to the plating processing section 5, and processed by the plating processing section 5.

[0026] For example, recesses such as trenches and vias 120 (see FIG. 3) are formed on the surface of the substrate W, and the plating processing section 5 fills such recesses with metal by electroless plating.

[0027] The substrate W processed by the plating processing section 5 is carried out from the plating processing section 5 by the substrate transport device 17 and placed on the delivery section 14. Then, the processed substrate W placed on the delivery section 14 is returned to the carrier C of the carrier mounting table 11 by the substrate transport device 13.

[0028] <Overview of Plating Department> Next, a schematic configuration of the plating processing section 5 will be described with reference to Fig. 2. Fig. 2 is a diagram showing the configuration of the plating processing section 5 according to an embodiment. The plating processing section 5 is configured, for example, as a single-wafer processing unit that processes substrates W one by one.

[0029] The plating processing section 5 is configured to perform liquid processing including electroless plating. The plating processing section 5 includes a chamber 51, a substrate holding section 52, a first plating solution supply section 53, and a second plating solution supply section 54. The first plating solution supply section 53 and the second plating solution supply section 54 are examples of chemical solution supply sections.

[0030] The substrate holding unit 52 is disposed in the chamber 51 and holds the substrate W horizontally. The first plating solution supply unit 53 supplies a first plating solution L1 to the surface (upper surface) of the substrate W held by the substrate holding unit 52. The second plating solution supply unit 54 supplies a second plating solution L2 to the surface (upper surface) of the substrate W held by the substrate holding unit 52.

[0031] In this embodiment, the substrate holding portion 52 has a chuck member 521 that vacuum-sucks the lower surface (rear surface) of the substrate W. This chuck member 521 is of a so-called vacuum chuck type.

[0032] A rotary motor 523 (rotation drive unit) is connected to the substrate holding unit 52 via a rotary shaft 522. When the rotary motor 523 is driven, the substrate holding unit 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 heat source such as a heater is provided inside the substrate holding unit 52.

[0033] The first plating solution supply section 53 has a first plating solution nozzle 531 that ejects (supplies) a first plating solution L1 onto the substrate W held by the substrate holding section 52, and a first plating solution supply source 532 that supplies the first plating solution L1 to the first plating solution nozzle 531.

[0034] Of these, the first plating solution supply source 532 is configured to supply a first plating solution L1, which has been heated or adjusted to a predetermined temperature, to the first plating solution nozzle 531 via a first plating solution pipe 533.

[0035] The temperature of the first plating solution L1 when it is discharged from the first plating solution nozzle 531 is, for example, from 40° C. to 70° C., and more preferably from 60° C. to 70° C. The first plating solution nozzle 531 is held by a nozzle arm 57 and configured to be movable.

[0036] The first plating solution L1 is a plating solution for a displacement-type electroless plating process (hereinafter also referred to as a displacement plating process). The first plating solution L1 contains, for example, copper (Cu) ions. Furthermore, the first plating solution L1 according to the embodiment contains a reducing agent at a rate smaller than a given rate, or does not contain a reducing agent.

[0037] Examples of reducing agents that may be contained in the first plating solution L1 include hypophosphorous acid, dimethylamine borane, and glyoxylic acid.

[0038] The second plating solution supply section 54 has a second plating solution nozzle 541 that ejects (supplies) a second plating solution L2 onto the substrate W held by the substrate holding section 52, and a second plating solution supply source 542 that supplies the second plating solution L2 to the second plating solution nozzle 541.

[0039] Of these, the second plating solution supply source 542 is configured to supply the second plating solution L2, which has been heated or adjusted to a predetermined temperature, to the second plating solution nozzle 541 via a second plating solution pipe 543.

[0040] The temperature of the second plating solution L2 when discharged from the second plating solution nozzle 541 is, for example, from 40° C. to 70° C., and more preferably from 60° C. to 70° C. The second plating solution nozzle 541 is held by a nozzle arm 57 and configured to be movable.

[0041] The second plating solution L2 is a plating solution for reduction-type electroless plating (hereinafter also referred to as reduction plating). The second plating solution L2 contains, for example, copper ions and a reducing agent having a larger proportion than that of the first plating solution L1. The reducing agent contained in the second plating solution L2 is, for example, hypophosphorous acid, dimethylamine borane, glyoxylic acid, etc.

[0042] In addition to the metal ions and the reducing agent, the second plating solution L2 according to the embodiment may contain a complexing agent, a pH adjuster, etc. The complexing agent that may be contained in the second plating solution L2 may be any agent capable of forming a complex with the copper ions, and examples of the complexing agent include oxycarboxylic acid or a salt thereof, aminocarboxylic acid or a salt thereof, triethanolamine, and glycerin.

[0043] Examples of such oxycarboxylic acids include lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, etc. Examples of such aminocarboxylic acids include nitrilotriacetic acid, ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, 1,3-propanediaminetetraacetic acid, etc.

[0044] Examples of pH adjusters that may be contained in the second plating solution L2 include sodium oxide, tetramethylammonium hydroxide (TMAH), potassium hydroxide, and ammonia.

[0045] The plating processing unit 5 further includes a cleaning liquid supply unit 55 that supplies a cleaning liquid L3 to the surface of the substrate W held by the substrate holding unit 52, and a rinsing liquid supply unit 56 that supplies a rinsing liquid L4 to the surface of the substrate W.

[0046] The cleaning liquid supply unit 55 supplies cleaning liquid L3 to the substrate W held and rotated by the substrate holding unit 52, thereby performing a pre-cleaning process on the substrate W. This cleaning liquid supply unit 55 has a cleaning liquid nozzle 551 that ejects cleaning liquid L3 onto the substrate W held by the substrate holding unit 52, and a cleaning liquid supply source 552 that supplies cleaning liquid L3 to the cleaning liquid nozzle 551.

[0047] Of these, the cleaning solution supply source 552 is configured to supply cleaning solution L3, which has been heated or adjusted to a predetermined temperature as described below, to the cleaning solution nozzle 551 via a cleaning solution pipe 553. The cleaning solution nozzle 551 is held by a nozzle arm 57 and is movable together with the first plating solution nozzle 531 and the second plating solution nozzle 541.

[0048] The cleaning solution L3 may be a dicarboxylic acid or a tricarboxylic acid. As the dicarboxylic acid, for example, an organic acid such as malic acid, succinic acid, malonic acid, oxalic acid, glutaric acid, adipic acid, or tartaric acid may be used. As the tricarboxylic acid, for example, an organic acid such as citric acid may be used.

[0049] The rinsing liquid supply unit 56 has a rinsing liquid nozzle 561 that discharges the rinsing liquid L4 onto the substrate W held by the substrate holder 52, and a rinsing liquid supply source 562 that supplies the rinsing liquid nozzle 561 with the rinsing liquid L4.

[0050] Of these, the rinsing solution nozzle 561 is held by a nozzle arm 57 and is movable together with the first plating solution nozzle 531 , the second plating solution nozzle 541 and the cleaning solution nozzle 551 .

[0051] Moreover, the rinse liquid supply source 562 is configured to supply the rinse liquid L4 to the rinse liquid nozzle 561 via a rinse liquid pipe 563. As the rinse liquid L4, for example, DIW (deionized water) or the like can be used.

[0052] A nozzle moving mechanism (not shown) is connected to the nozzle arm 57 that holds the first plating solution nozzle 531, the second plating solution nozzle 541, the cleaning solution nozzle 551, and the rinsing solution nozzle 561 described above.

[0053] This nozzle movement mechanism moves the nozzle arm 57 in horizontal and vertical directions. More specifically, the nozzle movement mechanism enables the nozzle arm 57 to move between a discharge position where the processing liquid (first plating liquid L1, second plating liquid L2, cleaning liquid L3, or rinsing liquid L4) is discharged onto the substrate W and a retracted position where the nozzle arm 57 is retracted from the discharge position.

[0054] Among these, the discharge position is not particularly limited as long as the processing liquid can be supplied to any position on the surface of the substrate W. For example, it is preferable to set the discharge position to a position where the processing liquid can be supplied to the center of the substrate W.

[0055] The discharge position of the nozzle arm 57 may be different when supplying the first plating liquid L1, the second plating liquid L2, the cleaning liquid L3, and the rinsing liquid L4 to the substrate W.

[0056] The retracted position is a position within the chamber 51 that does not overlap the substrate W when viewed from above and is away from the discharge position. When the nozzle arm 57 is positioned at the retracted position, interference between the moving lid body 6 and the nozzle arm 57 is avoided.

[0057] A cup 581 is provided around the substrate holder 52. This cup 581 is formed in a ring shape when viewed from above, and receives the processing liquid splashed from the substrate W when the substrate W is rotated, and guides it to a drain duct 583.

[0058] An atmosphere blocking cover 582 is provided on the outer periphery of the cup 581 to prevent the atmosphere around the substrate W from diffusing into the chamber 51. The atmosphere blocking cover 582 is formed in a cylindrical shape extending in the vertical direction and has an open upper end. A lid body 6, which will be described later, can be inserted into the atmosphere blocking cover 582 from above.

[0059] In the embodiment, the substrate W held by the substrate holding portion 52 is covered by a lid 6. The lid 6 has a ceiling portion 61 and a side wall portion 62 extending downward from the ceiling portion 61.

[0060] The ceiling portion 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.

[0061] 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 processing liquids such as the second plating liquid L2. More specifically, a seal ring 613 is provided on the outer periphery of the heater 63, and the heater 63 is sealed by this seal ring 613.

[0062] The first ceiling plate 611 and the second ceiling plate 612 are preferably resistant to corrosion by processing liquids such as the second plating liquid L2, and may be made of, for example, an aluminum alloy. To further improve 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).

[0063] A lid body moving mechanism 7 is connected to the lid body 6 via a lid body arm 71. The lid body moving mechanism 7 moves the lid body 6 horizontally and vertically. More specifically, the lid body moving mechanism 7 has a rotation motor 72 that moves the lid body 6 horizontally, and a cylinder 73 that moves the lid body 6 vertically.

[0064] Of these, the rotation motor 72 is attached on a support plate 74 that is provided so as to be movable up and down relative to the cylinder 73. Instead of the cylinder 73, an actuator (not shown) including a motor and a ball screw may be used.

[0065] The swivel motor 72 of the lid body moving mechanism 7 moves the lid body 6 between an upper position located above the substrate W held by the substrate holding part 52 and a retracted position retracted from the upper position. Of these, the upper position is a position facing the substrate W held by the substrate holding part 52 with a relatively large gap therebetween, and is a position overlapping the substrate W when viewed from above.

[0066] 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 body 6 is positioned at the retracted position, the moving nozzle arm 57 is prevented from interfering with the lid body 6. The rotation axis of the swing motor 72 extends in the vertical direction, and the lid body 6 is capable of swinging in the horizontal direction between the upper position and the retracted position.

[0067] The cylinder 73 of the lid moving mechanism 7 moves the lid 6 up and down to adjust the distance between the substrate W to which the second plating solution L2 has been supplied and the first ceiling plate 611 of the ceiling section 61. More specifically, the cylinder 73 positions the lid 6 at a lower position (the position indicated by the solid line in FIG. 2) and an upper position (the position indicated by the two-dot chain line in FIG. 2).

[0068] In this embodiment, the heater 63 is driven and the second plating solution L2 on the substrate holder 52 or the substrate W is heated when the cover 6 is positioned at the above-mentioned lower position.

[0069] 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 the second ceiling plate 612 of the lid 6 via supports 65. That is, a plurality of supports 65 protruding upward from the upper surface of the second ceiling plate 612 are provided on the second ceiling plate 612, and the lid cover 64 is placed on the supports 65.

[0070] The lid cover 64 is movable horizontally and vertically together with the lid 6. In addition, the lid cover 64 preferably has higher thermal insulation properties than the ceiling portion 61 and the side wall portion 62 in order to prevent heat from escaping from within the lid 6 to the surroundings.

[0071] For example, the lid cover 64 is preferably made of a resin material, and it is even more preferable that the resin material has heat resistance.

[0072] Thus, in this embodiment, the lid body 6 equipped with the heater 63 and the lid body cover 64 are integrally provided, and the cover unit 10 that covers the substrate holding portion 52 or the substrate W when positioned in the lower position is formed by the lid body 6 and the lid body cover 64.

[0073] A fan filter unit 59 that supplies clean air to the periphery of the lid 6 is provided at the top of the chamber 51. The fan filter unit 59 supplies air to the inside of the chamber 51 (particularly, the inside of the atmosphere blocking cover 582), and the supplied air flows toward the exhaust pipe 81.

[0074] A downflow of the air flowing downward is formed around the lid 6, and the gas vaporized from the processing liquid such as the second plating liquid L2 flows toward the exhaust pipe 81 by this downflow. In this way, the gas vaporized from the processing liquid is prevented from rising and diffusing into the chamber 51.

[0075] The gas supplied from the fan filter unit 59 described above is exhausted by the exhaust mechanism 8.

[0076] <Embodiment> Next, details of the plating process according to this embodiment will be described with reference to Fig. 3 to Fig. 7. Fig. 3 is an enlarged cross-sectional view showing the state of the surface of the substrate W before the first plating process according to this embodiment.

[0077] 3, elements (not shown) have already been formed on the substrate W. In the wiring formation process (so-called BEOL (Back End of Line)) after the element formation, various processes for filling the via 120 formed in the insulating film 110 on the wiring 100 with metal wiring will be described below.

[0078] 3, metal wiring 100 is formed on the substrate W, and an insulating film 110 is provided on the wiring 100. In the embodiment, for example, the entire insulating film 110 is made of an oxide film.

[0079] The wiring 100 according to the embodiment is made of an element that does not diffuse inside the insulating film 110, which is an oxide film. The wiring 100 is made of a conductive material containing, for example, Co, Ni, or Ru.

[0080] Furthermore, in the substrate W, a via 120 is formed at a given position in the insulating film 110. The via 120 is an example of a recess, and is formed so as to penetrate from the upper surface of the insulating film 110 to the wiring 100.

[0081] In addition, prior to the first plating process of the embodiment, a barrier layer 131 composed of Ta, TaN, etc. and a seed layer 132 composed of cobalt (Co) or a cobalt alloy are formed in sequence on the surface of the substrate W, including the inside of the via 120.

[0082] Here, in the embodiment, for example, the seed layer 132 made of cobalt or a cobalt alloy is formed by a CVD (Chemical Vapor Deposition) method.

[0083] Moreover, a method for forming the via 120 in the insulating film 110 of the substrate W can be appropriately adopted from conventionally known methods. Specifically, for example, a general-purpose technique using a fluorine-based or chlorine-based gas can be applied as a dry etching technique.

[0084] In particular, as a method for forming a via 120 with a large aspect ratio (ratio of depth to diameter), an ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching) technique that enables high-speed deep etching can be adopted.

[0085] For example, the so-called Bosch process, in which an etching step using sulfur hexafluoride (SF6) and a protection step using a gas such as C4F8 are repeatedly performed, can be suitably adopted.

[0086] As shown in FIG. 3, a via 120 is formed in an insulating film 110 on a wiring 100, and a substrate W on which a barrier layer 131 and a seed layer 132 are formed is loaded into the above-mentioned plating processing section 5, where a given plating process is performed.

[0087] 4 is a diagram for explaining the first plating process according to the embodiment. As shown in FIG. 4, in the plating process method according to the embodiment, first, the control unit 91 (see FIG. 1) controls the first plating solution supply unit 53 to discharge the first plating solution L1 from the first plating solution nozzle 531 onto the surface of the substrate W.

[0088] As a result, the control unit 91 performs a displacement plating process on the vias 120 (see FIG. 3) using the first plating solution L1.

[0089] By this substitution plating process, the cobalt surface layer of the seed layer 132 formed inside the via 120 is replaced with a copper thin film 133, as shown in Fig. 5. Fig. 5 is an enlarged cross-sectional view showing the state of the surface of the substrate W after the first plating process according to the embodiment.

[0090] 6, following the above-described first plating process, the control unit 91 (see FIG. 1) controls the second plating solution supply unit 54 to discharge the second plating solution L2 from the second plating solution nozzle 541 onto the surface of the substrate W. FIG. 6 is a view for explaining the second plating process according to the embodiment.

[0091] As a result, the control unit 91 performs reduction plating on the vias 120 (see FIG. 5) using the second plating solution L2.

[0092] 7, this reduction plating process forms a copper reduction plating film 134 using the copper thin film 133 exposed inside the via 120 as a catalyst, and the inside of the via 120 is filled with the reduction plating film 134. Fig. 7 is an enlarged cross-sectional view showing the state of the surface of the substrate W after the second plating process according to the embodiment.

[0093] In this manner, in the embodiment, the thin film 133 formed by the displacement plating process is used as a catalyst to form the reduced plating film 134, and the inside of the via 120 is filled with the reduced plating film 134. This makes it possible to form good copper wiring without voids or seams inside the via 120, which has a large aspect ratio and is difficult to form copper wiring in.

[0094] In the embodiment, the reduction plating is not performed directly on the seed layer 132 made of cobalt, but rather the surface layer of the seed layer 132 is replaced with a copper thin film 133 and then the reduction plating is performed. This makes it possible to fill the inside of the via 120 with copper wiring more satisfactorily than when the copper reduction plating film 134 is formed using cobalt as a catalyst.

[0095] In addition, if reduction plating is to be performed on a copper seed layer, the copper seed layer can only be formed by a normal PVD method, and therefore, there is a risk that a homogeneous seed layer cannot be formed inside the via 120, particularly when the inner diameter of the via 120 is reduced as the multilayer wiring becomes finer.

[0096] Furthermore, due to the formation of a non-uniform seed layer inside the via 120, there is a risk that the inside of the via 120 cannot be filled satisfactorily with the reduction plating film 134 (ie, copper wiring).

[0097] However, in the embodiment, since the cobalt seed layer 132, which can be formed by a method other than the PVD method, is used, a more homogeneous seed layer 132 can be formed inside the via 120 than when a copper seed layer is used. Therefore, according to the embodiment, the inside of the via 120 can be filled with copper wiring more satisfactorily than when a copper seed layer is used.

[0098] In addition, in the embodiment, the cobalt seed layer 132 may be formed by a CVD method. This allows a more uniform seed layer 132 to be formed inside the via 120. Therefore, according to the embodiment, the inside of the via 120 can be more effectively filled with copper wiring.

[0099] In the embodiment, the cobalt seed layer 132 may have a thickness of 1 nm or more. This allows the seed layer 132 to be formed in the via 120 in a film shape rather than an island shape, and therefore allows a more uniform seed layer 132 to be formed in the via 120. Therefore, according to the embodiment, the inside of the via 120 can be more satisfactorily filled with copper wiring.

[0100] In the embodiment, it is more preferable that the cobalt seed layer 132 has a thickness of 2 (nm) to 5 (nm). This makes it possible to form a more uniform seed layer 132 inside the via 120 and to suppress deterioration of electrical resistance due to the thick cobalt seed layer 132.

[0101] Next, the first plating process and the second plating process described above will be described in detail. The first plating process is performed by supplying a first plating solution L1 to the substrate W at, for example, room temperature or a temperature higher than room temperature (for example, 23 (°C) to 70 (°C)).

[0102] In this manner, by carrying out the displacement plating process with the first plating solution L1 at a temperature higher than room temperature, the surface layer of the seed layer 132 can be efficiently displaced with the thin film 133.

[0103] The first plating process is preferably performed by controlling the rotation speed of the substrate W to 1000 (rpm) or less. This makes it possible to prevent the first plating liquid L1 from being shaken off and running out on the surface of the substrate W. Therefore, according to the embodiment, the displacement plating process can be performed evenly over the entire surface of the substrate W.

[0104] The first plating process may be performed, for example, by controlling the rotation speed of the substrate W at a low speed (for example, about 20 rpm) to form a puddle (puddle) of the first plating liquid L1 on the surface of the substrate W. This makes it possible to reduce the amount of the first plating liquid L1 used in the first plating process.

[0105] Furthermore, the first plating process may be performed, for example, by repeatedly forming a puddle of the first plating liquid L1 on the surface of the substrate W and shaking off the puddle.

[0106] As a result, in the first plating process according to the embodiment, the amount of the first plating solution L1 used can be reduced, and impurities such as substituted cobalt can be removed from the first plating solution L1, so that a thin film 133 in good condition can be formed.

[0107] Furthermore, the first plating process may be performed, for example, by controlling the rotation speed of the substrate W at a relatively high speed (for example, about 250 (rpm)) and draining the continuously supplied first plating solution L1 from the edge of the substrate W as needed. This makes it possible to remove impurities such as substituted cobalt from the first plating solution L1 in the first plating process, thereby making it possible to form a thin film 133 in good condition.

[0108] The first plating process may be performed using, for example, a first plating solution L1 that does not contain a reducing agent, which can suppress reaction between metal ions and the reducing agent in the first plating solution L1 stored in the first plating solution supply source 532 (see FIG. 2), thereby improving the processing efficiency of the first plating process.

[0109] The second plating process according to the embodiment is preferably performed by controlling the rotation speed of the substrate W to 100 rpm or less. This allows the reduction plating process to be performed while forming a puddle of the second plating liquid L2 on the surface of the substrate W, thereby reducing the amount of the second plating liquid L2 used in the second plating process.

[0110] The second plating process may be performed, for example, by covering the substrate W on which the puddle of the second plating liquid L2 has been formed with the lid body 6 and heating the puddle of the second plating liquid L2 to a given temperature (for example, 40 (°C) to 70 (°C) by the heater 63 of the lid body 6.

[0111] This allows the reduction plating process to be performed using the second plating solution L2 at a temperature higher than room temperature, so that even if the vias 120 are miniaturized, the insides of the vias 120 can be more effectively filled with the reduction plating film 134.

[0112] In addition, the temperature of the second plating solution L2 in the second plating process is preferably higher than the temperature of the first plating solution L1 in the first plating process, which allows the second plating process, which takes more time, to be carried out efficiently, thereby reducing the overall processing time for the substrate W.

[0113] In the second plating process, first, a second plating liquid L2 is supplied to the surface of the substrate W, and a puddle of the second plating liquid L2 is formed on the surface of the substrate W.

[0114] Next, the substrate W on which the puddle of the second plating liquid L2 has been formed is covered with the lid body 6. In this case, first, the rotation motor 72 of the lid body moving mechanism 7 is driven to rotate the lid body 6 in the horizontal direction and position it at the upper position (the position indicated by the two-dot chain line in FIG. 2).

[0115] Then, the cylinder 73 of the lid moving mechanism 7 is driven, and the lid 6 located at the upper position is lowered to the processing position. As a result, the distance between the second plating solution L2 on the substrate W and the first ceiling plate 611 of the lid 6 becomes a given distance, and the side wall 62 of the lid 6 is disposed on the outer periphery of the substrate W.

[0116] In the embodiment, the lower end of the side wall portion 62 of the lid 6 is positioned at a position lower than the lower surface of the substrate W. In this manner, the substrate W is covered by the lid 6, and the space around the substrate W is closed.

[0117] Next, the heater 63 is turned on to heat the second plating solution L2 that has been piled on the substrate W. The set temperature of the heater 63 is fixed to the target temperature at which the second plating solution L2 reaches the above-mentioned given temperature. The target temperature is, for example, 100 (°C) to 140 (°C).

[0118] When the temperature of the second plating solution L2 rises to a temperature at which the components precipitate, the components of the second plating solution L2 precipitate on the surface of the thin film 133, and a reduced plating film 134 is formed.

[0119] Then, when a time set in advance as the processing time of the heating process has elapsed since the heating process by the heater 63 has started, the heater 63 is turned off.

[0120] Next, the lid body 6 is retracted from the substrate W. For example, the lid body moving mechanism 7 is driven to position the lid body 6 at the retracted position, and then the rotation motor 72 of the lid body moving mechanism 7 is driven to rotate the lid body 6, which is positioned at the upper position, in the horizontal direction and position it at the retracted position. This completes the second plating process.

[0121] It is preferable that the surface of the substrate W is wet with the first plating liquid L1 (i.e., a liquid film of the first plating liquid L1 is formed on the surface of the substrate W) during the period from the end of the first plating process to the start of the second plating process. This makes it possible to prevent the thin film 133 formed in the first plating process from being oxidized by air.

[0122] That is, in the embodiment, the second plating process can be carried out using the thin film 133 in good condition as a catalyst, so that the inside of the via 120 can be filled with the reduced plating film 134 more satisfactorily.

[0123] <Various modified examples> Next, various modified examples of the embodiment will be described with reference to Figures 8 to 10. Figure 8 is a view for explaining a first plating treatment according to a modified example of the embodiment.

[0124] As shown in FIG. 8, in the plating processing method according to the modified example, first, the control unit 91 (see FIG. 1) controls the first plating solution supply unit 53 to eject the first plating solution L1 from the first plating solution nozzle 531 onto the surface of the substrate W.

[0125] As a result, the control unit 91 performs a displacement plating process on the via 120 (see FIG. 3) using the first plating solution L1. By this displacement plating process, the cobalt surface layer of the seed layer 132 formed inside the via 120 is replaced with a copper thin film 133, as shown in FIG. 5. Note that the first plating process according to the modified example is similar to that of the above-described embodiment, and therefore a detailed description thereof will be omitted.

[0126] 9 is a diagram for explaining a second plating process according to a modified example of the embodiment. As shown in Fig. 9, in the plating process method according to the modified example, following the above-mentioned first plating process, the control unit 91 (see Fig. 1) controls the first plating solution supply unit 53 to discharge the first plating solution L1 from the first plating solution nozzle 531 onto the surface of the substrate W.

[0127] Furthermore, in the modified example, the control unit 91 controls the second plating solution supply unit 54 to discharge the third plating solution L2a from the second plating solution nozzle 541 onto the surface of the substrate W. The third plating solution L2a contains a larger proportion of a reducing agent than the first plating solution L1, and does not contain copper ions.

[0128] In the modified example, in the second plating process, the control unit 91 discharges the first plating liquid L1 and the third plating liquid L2a onto the surface of the substrate W and mixes them on the surface of the substrate W to generate the second plating liquid L2. Then, the control unit 91 performs a reduction plating process on the vias 120 (see FIG. 5) using the generated second plating liquid L2.

[0129] As a result, a reduced plating film 134 (see FIG. 7) is formed in the via 120. Note that the second plating process according to the modified example is similar to that of the above-described embodiment except that the first plating solution L1 and the third plating solution L2a are simultaneously discharged instead of the second plating solution L2, and therefore a detailed description thereof will be omitted.

[0130] In the modification described above, similarly to the above-mentioned embodiment, the surface layer of the seed layer 132 made of cobalt is replaced with a copper thin film 133, and then reduction plating is performed. Therefore, according to the modification, similarly to the above-mentioned embodiment, the inside of the via 120 can be satisfactorily filled with copper wiring.

[0131] In a modified example, the first plating solution L1 does not contain a reducing agent, and the third plating solution L2a contains a reducing agent and unavoidable impurities. In the modified example, the first plating solution L1 and the third plating solution L2a are mixed on the surface of the substrate W to generate the second plating solution L2.

[0132] This makes it possible to prevent the reaction between the copper ions and the reducing agent in the stored second plating solution L2 from progressing during standby. In other words, in the modified example, deterioration of the second plating solution L2 used in the reduction plating process can be prevented, so that the inside of the via 120 can be more satisfactorily filled with copper wiring.

[0133] In the modified examples described above, an example has been shown in which the first plating liquid L1 and the third plating liquid L2a are mixed on the surface of the substrate W to generate the second plating liquid L2. However, the present disclosure is not limited to such an example, and for example, the first plating liquid L1 and the third plating liquid L2a may be mixed above the substrate W (i.e., before the discharged first plating liquid L1 and third plating liquid L2a reach the substrate W) to generate the second plating liquid L2.

[0134] In the above-described modified example, the first plating solution L1 and the third plating solution L2a are both discharged in the second plating process, but the present disclosure is not limited to such an example. Fig. 10 is a diagram for explaining the second plating process according to another modified example of the embodiment.

[0135] 10, in the second plating process, the control unit 91 (see FIG. 1) controls the second plating solution supply unit 54 to discharge only the third plating solution L2a from the second plating solution nozzle 541 onto the surface of the substrate W on which the liquid film of the first plating solution L1 has been formed. In this way, the control unit 91 mixes the discharged third plating solution L2a with the liquid film of the first plating solution L1 on the surface of the substrate W to generate the second plating solution L2.

[0136] Then, the control unit 91 performs a reduction plating process on the vias 120 (see FIG. 4) using the generated second plating solution L2. As a result, a reduction plating film 134 (see FIG. 6) is formed in the vias 120.

[0137] In the other modified example described above, similar to the above-mentioned embodiment, the surface layer of the seed layer 132 made of cobalt is substituted with a thin copper film 133 by a displacement plating process, and then a reduction plating process is performed. Therefore, according to the other modified example, similar to the above-mentioned embodiment, the inside of the via 120 can be satisfactorily filled with copper wiring.

[0138] Furthermore, in another modified example, as in the modified example described above, deterioration of the second plating solution L2 used in the reduction plating process can be suppressed, so that the interior of the via 120 can be filled with copper wiring more satisfactorily.

[0139] In the embodiments and various modified examples described so far, an example has been shown in which the via 120 is filled with copper wiring (reduced plating film 134), but the present disclosure is not limited to such an example, and various recesses (e.g., trenches, etc.) formed on the surface of the substrate W may also be filled with copper wiring.

[0140] The plating processing apparatus (substrate processing apparatus 1) according to the embodiment includes a substrate holding unit 52 that rotatably holds a substrate W, a chemical solution supply unit (first plating solution supply unit 53, second plating solution supply unit 54) that supplies a chemical solution to the substrate W, and a control unit 91 that controls each unit. The control unit 91 holds the substrate W, in which a seed layer 132 of cobalt or a cobalt alloy is formed in a recess (via 120), by the substrate holding unit 52. The control unit 91 also performs a substitution plating process on the substrate W, using a first plating solution L1 containing copper ions to substitute the surface layer of the seed layer 132 with copper. After the substitution plating process, the control unit 91 also performs a reduction plating process on the recess (via 120) by using a second plating solution L2 containing copper ions and a reducing agent on the substrate W. This allows the interior of the via 120 to be satisfactorily filled with copper wiring.

[0141] Moreover, in the plating processing apparatus (substrate processing apparatus 1) according to the embodiment, the chemical solution supply unit is configured to be able to supply a first plating solution L1 having a reducing agent content smaller than a given ratio, and a third plating solution L2a having a reducing agent content greater than that of the first plating solution L1, to the substrate W. Furthermore, the control unit 91 performs a reduction plating process using a second plating solution L2 generated by mixing the first plating solution L1 and the third plating solution L2a on the substrate W. This allows the interior of the via 120 to be more satisfactorily filled with copper wiring.

[0142] In the plating processing apparatus (substrate processing apparatus 1) according to the embodiment, the control unit 91 controls the rotation speed of the substrate W to 1000 (rpm) or less during the substitution plating process. This allows the substitution plating process to be performed evenly over the entire surface of the substrate W.

[0143] In the plating processing apparatus (substrate processing apparatus 1) according to the embodiment, the control unit 91 controls the rotation speed of the substrate to 100 (rpm) or less during reduction plating, thereby reducing the amount of the second plating solution L2 used.

[0144] <Plating process details> Next, the plating process performed by the substrate processing apparatus 1 according to the embodiment will be described in detail with reference to Fig. 11. Fig. 11 is a flowchart showing the procedure of the plating process according to the embodiment.

[0145] First, the control unit 91 controls the substrate transport devices 13, 17 to transport the substrate W from the carrier C to the inside of the plating processing unit 5, and prepares the substrate W by holding the substrate W with the substrate holding unit 52 (step S101).

[0146] Next, the control unit 91 performs a cleaning process on the substrate W (step S102). In this case, first, the rotation motor 523 is driven to rotate the substrate W at a predetermined rotation speed. Next, the nozzle arm 57, which has been positioned at the retreated position (the position indicated by the solid line in FIG. 2), moves to a discharge position above the center of the substrate W.

[0147] Next, the cleaning liquid L3 is supplied from the cleaning liquid nozzle 551 to the rotating substrate W to clean the surface of the substrate W. As a result, deposits and the like attached to the substrate W are removed from the substrate W. The cleaning liquid L3 supplied to the substrate W is discharged to the drain duct 583.

[0148] Next, the control unit 91 performs a rinsing process on the substrate W (step S103). In this case, the rinsing liquid L4 is supplied from the rinsing liquid nozzle 561 to the rotating substrate W, and the surface of the substrate W is rinsed. This washes away the cleaning liquid L3 remaining on the substrate W. The rinsing liquid L4 supplied to the substrate W is discharged to the drain duct 583.

[0149] Next, the control unit 91 performs a first plating process on the substrate W (step S104). In this case, the first plating solution L1 is supplied from the first plating solution nozzle 531 to the substrate W rotating at 1000 (rpm) or less, and the cobalt seed layer 132 formed inside the via 120 is subjected to a displacement plating process.

[0150] As a result, a thin copper film 133 is formed on the surface of the cobalt seed layer 132. The first plating solution L1 supplied to the substrate W is discharged to the drain duct 583.

[0151] Next, the control unit 91 performs a second plating process on the substrate W (step S105). In this case, the second plating solution L2 is supplied from the second plating solution nozzle 541 to the substrate W rotating at 100 (rpm) or less, and a puddle of the second plating solution L2 is formed on the surface of the substrate W. As a result, a reduced plating film 134 is formed inside the via 120 using the thin copper film 133 formed in the first plating process as a catalyst.

[0152] Next, the control unit 91 covers the substrate W with the lid 6 and operates the heater 63 to heat the puddle of the second plating solution L2 formed on the surface of the substrate W (step S106). This promotes the formation of the reduced plating film 134. Note that the details of the process of step S106 have been described above, so a detailed description thereof will be omitted.

[0153] Next, the control unit 91 performs a rinsing process on the substrate W (step S107). In this case, first, the cover 6 is retracted from above the substrate W. Next, the rotation motor 523 is driven to rotate the substrate W at a predetermined rotation speed.

[0154] Then, the rinsing liquid L4 is supplied from the rinsing liquid nozzle 561 to the rotating substrate W, thereby rinsing the surface of the substrate W. This washes away the second plating liquid L2 remaining on the substrate W. The rinsing liquid L4 supplied to the substrate W is discharged to the drain duct 583.

[0155] Next, the rinsed substrate W is dried (step S108). In this case, for example, the rotation speed of the substrate W is increased to be higher than the rotation speed of the rinse process (step S107) to rotate the substrate W at a high speed. As a result, the rinsing liquid L4 remaining on the substrate W is shaken off, and the substrate W is dried.

[0156] When the drying process is completed, the substrate W is removed from the plating processing section 5 by the substrate transport device 17 and transported to the delivery section 14. The substrate W transported to the delivery section 14 is then removed from the delivery section 14 by the substrate transport device 13 and stored in the carrier C. This completes a series of plating processes for one substrate W.

[0157] The plating method according to the embodiment includes a preparation step (step S101), a first plating step (step S104), and a second plating step (step S105). In the preparation step (step S101), a substrate W is prepared in which a seed layer 132 of cobalt or a cobalt alloy is formed in a recess (via 120). In the first plating step (step S104), a substitution plating process is performed on the substrate W using a first plating solution L1 containing copper ions to substitute the surface layer of the seed layer 132 with copper. In the second plating step (step S105), after the first plating step (step S104), a reduction plating process is performed on the recess (via 120) using a second plating solution L2 containing copper ions and a reducing agent. This allows the interior of the via 120 to be satisfactorily filled with copper wiring.

[0158] In the plating method according to the embodiment, the second plating step is performed using a second plating solution L2 produced by mixing a first plating solution L1 containing a reducing agent at a smaller ratio than a given ratio with a third plating solution L2a containing a reducing agent at a larger ratio than that of the first plating solution L1. This allows the interior of the via 120 to be filled with copper wiring more satisfactorily.

[0159] In the plating method according to the embodiment, the first plating solution L1 does not contain a reducing agent, which allows the interior of the via 120 to be filled with copper wiring more effectively.

[0160] In the plating method according to the embodiment, the second plating step (step S105) is performed on the substrate W wet with the first plating liquid L1. This allows the inside of the via 120 to be filled with the reduced plating film 134 more satisfactorily.

[0161] In the plating method according to the embodiment, the seed layer 132 is formed by a CVD method, which allows the inside of the via 120 to be filled with copper wiring more satisfactorily.

[0162] In the plating method according to the embodiment, the seed layer 132 has a thickness of 1 nm or more, which allows the interior of the via 120 to be filled with copper wiring more satisfactorily.

[0163] Furthermore, in the plating method according to the embodiment, the second plating solution L2 has a higher temperature than the first plating solution L1, which makes it possible to reduce the overall processing time for the substrate W.

[0164] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0165] The disclosed embodiments should be considered to be illustrative and not restrictive in all respects. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0166] 1. Substrate processing equipment (example of plating processing equipment) 5. Plating section 52 Board holding part 53 First plating solution supply unit (an example of a chemical solution supply unit) 54 Second plating solution supply unit (an example of a chemical solution supply unit) 91 Control Unit 120 Via (an example of a recess) 132 Seed Layer 133 Thin Film 134 Reduction plating film L1 First plating solution L2 Second plating solution L2a Third plating solution W substrate

Claims

1. A preparation step of preparing a substrate having a seed layer of cobalt or a cobalt alloy formed in a recess; a first plating step of performing a substitution plating process on the substrate using a first plating solution containing copper ions to substitute a surface layer of the seed layer with copper; a second plating step of performing a reduction plating process on the recessed portion of the substrate using a second plating solution containing copper ions and a reducing agent after the first plating step; Including, the first plating step and the second plating step are performed by supplying the first plating solution or the second plating solution to the substrate while rotating the substrate by a substrate holder that rotatably holds the substrate; The rotation speed of the substrate in the first plating step is 1000 (rpm) or less, and the rotation speed of the substrate in the second plating step is 100 (rpm) or less. Plating process.

2. The first plating solution does not contain a reducing agent. The plating method according to claim 1 .

3. The second plating step is performed on the substrate wetted with the first plating solution. The plating method according to claim 1 or 2.

4. The seed layer is formed by a CVD method. The plating method according to any one of claims 1 to 3.

5. The seed layer has a thickness of 1 nm or more. The plating method according to any one of claims 1 to 4.

6. The second plating solution has a higher temperature than the first plating solution. The plating method according to any one of claims 1 to 5.

7. a substrate holder that rotatably holds the substrate; A chemical supply unit that supplies a chemical to the substrate; A control unit for controlling each unit; Equipped with The control unit is The substrate having a cobalt or cobalt alloy seed layer formed in the recess is held by the substrate holder; supplying a first plating solution containing copper ions to the substrate while rotating the substrate, thereby performing a substitution plating process for substituting a surface layer of the seed layer with copper; after the displacement plating process, a second plating solution containing copper ions and a reducing agent is supplied to the substrate while rotating the substrate, thereby performing a reduction plating process on the recessed portion; The rotation speed of the substrate in the substitution plating process is 1000 (rpm) or less, and the rotation speed of the substrate in the reduction plating process is 100 (rpm) or less. Plating processing equipment.

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