Plating apparatus and plating method

Abstract

The present invention improves in-plane uniformity of a plating film formed on a rectangular substrate.　The present invention comprises: a plating tank; a substrate holder configured to hold a rectangular substrate, the substrate holder having an electrical contact configured to supply power to a first side and a second side of the rectangular substrate, wherein the first side and the second side face each other; an anode disposed in the plating tank so as to face the rectangular substrate held by the substrate holder; and an anode mask that defines an opening corresponding to the outer shape of the rectangular substrate, the anode mask having a first mask member and a second mask member, wherein the first mask member defines a first recessed part so that the opening expands to a central portion of a first opening side corresponding to the first side of the rectangular substrate in the opening, the second mask member defines a second recessed part so that the opening expands to a central portion of a second opening side corresponding to the second side of the rectangular substrate in the opening, and the anode mask is configured so that the distance between the first mask member and the second mask member can be adjusted.

Description

Plating apparatus and plating method

[0001] The present application relates to a plating apparatus and a plating method.

[0002] Conventionally, wiring has been formed in minute wiring grooves, holes, or resist openings provided on the surface of a substrate such as a semiconductor wafer, or bumps (protruding electrodes) that electrically connect to package electrodes, etc., have been formed on the surface of the substrate. Known methods for forming these wiring and bumps include electrolytic plating, vapor deposition, printing, and ball bumping. With the increase in the number of I / Os on semiconductor chips and the trend toward finer pitches, electrolytic plating, which allows for finer wiring and has relatively stable performance, has become increasingly popular.

[0003] When forming wiring or bumps using electrolytic plating, a low-electrical-resistance seed layer (power supply layer) is formed on the surface of a barrier metal provided in wiring grooves, holes, or resist openings on a substrate. A plating film grows on the surface of this seed layer. Known substrate shapes include circular and rectangular.

[0004] A rectangular substrate has corners, and the distance from the center of the substrate to the periphery of the substrate varies depending on the location. Therefore, when using an anode mask with openings of a similar shape to the rectangular substrate, the plating film thickness distribution tendency may differ near the corners and at the center of the sides (the center between the vertices). In particular, when electrical contacts are arranged on the periphery of all sides of a rectangular substrate, the final plating film thickness tends to be smaller in areas near the corners, which are relatively far from the center. For this reason, Patent Document 1 proposes an anode mask in which the center of the opening side protrudes inward.

[0005] Patent No. 7285389

[0006] For rectangular substrates, instead of placing electrical contacts on the peripheries of all sides of the rectangular substrate, electrolytic plating is sometimes performed with electrical contacts placed on the peripheries of a pair of opposing sides. In such cases, if an anode mask with openings similar in shape to the rectangular substrate is used, the final plating thickness tends to be larger near the corners and smaller, especially near the center of the sides where no electrical contacts are located. This effect varies depending on the resist opening ratio of the rectangular substrate being processed, the plating recipe, and the use of the plating solution.

[0007] The present invention has been made in view of the above-mentioned problems, and one of its objects is to improve the in-plane uniformity of a film plated on a rectangular substrate.

[0008] According to one embodiment, a plating apparatus is proposed, which comprises: a plating tank; a substrate holder configured to hold a rectangular substrate, the substrate holder having electrical contacts configured to supply power to opposing first and second sides of the rectangular substrate; an anode arranged in the plating tank so as to face the rectangular substrate held by the substrate holder; and an anode mask that defines an opening corresponding to the outer shape of the rectangular substrate, the anode mask having: a first mask member that defines a first recess so that the opening extends to a center of a first opening edge in the opening corresponding to the first side of the rectangular substrate; and a second mask member that defines a second recess so that the opening extends to a center of a second opening edge in the opening corresponding to the second side of the rectangular substrate, the anode mask being configured so that the distance between the first mask member and the second mask member can be adjusted.

[0009] According to another embodiment, a method for plating a rectangular substrate by passing an electric current between an anode and the rectangular substrate in a plating apparatus is proposed, the method comprising: an anode mask defining an opening corresponding to the outer shape of the rectangular substrate, the anode mask having a first mask member defining a first recess so that the opening extends to a center of a first opening edge in the opening corresponding to a first side of the rectangular substrate; and a second mask member defining a second recess so that the opening extends to a center of a second opening edge in the opening corresponding to a second side of the rectangular substrate opposite the first side; adjusting the distance between the first mask member and the second mask member; holding the rectangular substrate with a substrate holder having electrical contacts configured to supply power to the first side and the second side of the rectangular substrate; and passing an electric current between the anode and the polygonal substrate.

[0010] FIG. 1 is an overall layout diagram of a plating apparatus of an embodiment; FIG. 2 is a schematic side cross-sectional view (longitudinal cross-sectional view) of a plating unit provided in the plating apparatus; FIG. 3 is a schematic front view of a substrate holder used in the plating unit; FIG. 4 is a view showing an anode mask in one embodiment from the substrate side; FIG. 5 is a view showing an anode mask in one embodiment from the substrate side; FIG. 6 is a schematic view showing a plating film thickness on a rectangular substrate when a conventional anode mask of a comparative example is used; and FIG. 7 is a schematic view showing a plating film thickness on a rectangular substrate when the anode mask of this embodiment is used.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings described below, identical or corresponding components are designated by the same reference numerals, and redundant description will be omitted.

[0012] FIG. 1 shows the overall layout of a plating apparatus according to an embodiment. As shown in FIG. 1, this plating apparatus includes two cassette tables 102 on which cassettes 100 containing substrates such as semiconductor wafers are mounted, an aligner 104 that aligns the substrates in a predetermined direction, and a rinse dryer 106 that dries the substrates after plating. Near the rinse dryer 106, there is provided a substrate loading / unloading section 120 on which a substrate holder 30 is placed for loading and unloading substrates. At the center of these units 100, 104, 106, and 120, there is provided a substrate transfer device 122 consisting of a transfer robot that transfers substrates between these units.

[0013] The substrate loading / unloading section 120, the stocker 124 for storing and temporarily placing the substrate holders 30, the pre-wet tank 126 for immersing the substrates in pure water, the pre-soak tank 128 for etching away the oxide film on the surface of a conductive layer such as a seed layer formed on the surface of the substrate, the first cleaning tank 130a for cleaning the substrates after pre-soaking together with the substrate holders 30 with a cleaning liquid (such as pure water), the blow tank 132 for draining the substrates after cleaning, the second cleaning tank 130b for cleaning the substrates after plating together with the substrate holders 30 with a cleaning liquid, and the plating unit 10 are arranged in this order, as an example.

[0014] The plating unit 10 is configured by accommodating a plurality of plating tanks 14 inside an overflow tank 136. Each plating tank 14 accommodates one substrate therein, and the substrate is immersed in the plating solution held therein to perform plating such as copper plating on the surface of the substrate.

[0015] The plating apparatus includes a substrate holder transport device 140, which is positioned to the side of each of these devices and transports the substrate holder 30 together with the substrate between these devices, and which employs, for example, a linear motor system. This substrate holder transport device 140 includes a first transporter 142 that transports substrates between the substrate loading / unloading section 120, the stocker 124, the pre-wet tank 126, the pre-soak tank 128, the first cleaning tank 130a, and the blow tank 132, and a second transporter 144 that transports substrates between the first cleaning tank 130a, the second cleaning tank 130b, the blow tank 132, and the plating unit 10. The plating apparatus may include only the first transporter 142, without including the second transporter 144.

[0016] On the opposite side of the overflow tank 136 from the substrate holder transport device 140, a paddle drive device 146 is arranged which drives a paddle 16 (see Figure 2) located inside each plating tank 14 as a stirring rod for stirring the plating solution in the plating tank 14.

[0017] The substrate loading / unloading section 120 is equipped with a flat loading plate 152 that can slide laterally along rails 150. The two substrate holders 30 are placed in parallel and horizontally on this loading plate 152, and after a substrate is transferred between one substrate holder 30 and the substrate transport device 122, the loading plate 152 is slid laterally, and the substrate is transferred between the other substrate holder 30 and the substrate transport device 122.

[0018] The plating apparatus also includes a control device 17 for controlling the entire apparatus. The control device 17 can be configured, for example, as a general computer or a dedicated computer provided with an input / output interface for an operator.

[0019] Fig. 2 is a schematic side cross-sectional view (longitudinal cross-sectional view) of a plating unit 10 provided in the plating apparatus shown in Fig. 1. As shown in Fig. 2, the plating unit 10 has a plating tank 14 configured to contain a plating solution, a substrate holder 30, and an anode holder 13, and an overflow tank (not shown). The anode holder 13 is configured to hold an anode 12 having a metal surface.

[0020] The plating unit 10 includes a regulation plate 20 for adjusting the electric field between the substrate Wf and the anode 12, and a paddle 16 for stirring the plating solution. The regulation plate 20 is disposed between the substrate holder 30 and the anode 12. As a specific example, the lower end of the regulation plate 20 is inserted between a pair of protruding members 28 provided on the floor of the plating tank 14, thereby fixing the regulation plate 20 to the plating tank 14. The regulation plate 20 has an arm (not shown) protruding outward near its upper end, and may be suspended and supported within the stocker 124 shown in FIG. 1 by hooking the arm onto the upper surface of the peripheral wall of the stocker 124. The paddle 16 is disposed between the substrate holder 30 and the regulation plate 20.

[0021] FIG. 3 is a diagram showing a schematic configuration of a substrate holder in this embodiment. The substrate holder 30 is configured to hold a substrate Wf in the plating tank 14. In this embodiment, the substrate Wf has a rectangular shape elongated in the vertical direction, but this is not limited to this example and may be a rectangular shape such as a square. The substrate holder 30 includes a main body 31 that holds the substrate Wf and an arm 32 provided at the upper end of the main body 31. The substrate holder 30 is transported with the arm 32 held by the transporters 142 and 144. As indicated by dashed lines in FIG. 3 , the main body 31 includes electrical contacts 34 for supplying power to two opposing sides (first and second sides) of the rectangular substrate Wf. In the example shown in FIG. 3 , the electrical contacts 34 extend along the longitudinal direction of the rectangular substrate Wf and are configured to contact the entire edges of the two longitudinal sides of the substrate Wf. The electrical contacts 34 are electrically connected to a power supply contact 36 provided on the arm 32. 3, the power supply contact 36 is provided on one end of the arm portion 32, but it may be provided on both ends of the arm portion 32. When the substrate holder 30 is transported to each treatment tank and immersed in the treatment solution therein, the arm portion 32 is placed on an arm receiving member (not shown) of each treatment tank. When the substrate holder 30 is placed in the plating tank 14, the power supply contact 36 comes into contact with an electrical contact (not shown) provided on the arm receiving member of the plating tank 14. As a result, power is supplied from the plating power source 15 (see FIG. 2), and a current flows between the substrate Wf and the anode 12, forming a plating film on the surface to be plated of the substrate Wf.

[0022] Referring again to Figure 2, the anode holder 13 has an anode mask 18 for adjusting the electric field between the anode 12 and the substrate Wf. The anode mask 18 is a substantially plate-shaped member made of, for example, a dielectric material, and is provided on the front surface of the anode holder 13. Here, the front surface of the anode holder 13 refers to the surface facing the substrate holder 30. In other words, the anode mask 18 is disposed between the anode 12 and the substrate holder 30. An opening 18a is formed in the approximate center of the anode mask 18, through which a current flows between the anode 12 and the substrate Wf.

[0023] 4 and 5 are views showing the anode mask 18 in one embodiment from the substrate Wf side. The anode mask 18 has multiple mask members 181-184 that define rectangular openings corresponding to the rectangular shape of the substrate Wf. In the example shown in FIGS. 4 and 5, four mask members 181-184 are provided corresponding to the four sides of the rectangular substrate Wf. For ease of viewing, the pair of opposing mask members 181, 183 that define the long sides of the opening 18a and the pair of mask members 182, 184 that define the short sides are hatched differently.

[0024] The mask members 181, 183 that define the long sides of the opening 18a have side portions 181a, 183a that run along the long sides of the substrate Wf, and recesses 181b, 183b that are provided at positions corresponding to the centers of the long sides of the substrate Wf and that extend outward from the anode mask 18. In other words, the mask members 181, 183 have recesses 181b, 183b formed in the centers of the opening sides that define the opening 18a so that the opening 18a widens. As an example, the recesses 181b, 183b have a trapezoidal shape that narrows as it moves away from the center of the opening 18a of the anode mask 18, but they may also have other shapes, such as an arc shape.

[0025] The mask members 181 and 183 are configured so that the distance between them can be adjusted. The mask members 181 and 183 may be configured so that they can move toward and away from each other, i.e., in directions perpendicular to the sides 181a and 183a. Alternatively, the mask members 181 and 183 may be configured so that their distances from a position corresponding to the center of the anode 12 are equal. FIG. 4 illustrates an anode mask 18 in which the mask members 181 and 183 are relatively far apart, while FIG. 5 illustrates an anode mask 18 in which the mask members 181 and 183 are relatively close together. Note that FIGS. 4 and 5 illustrate an example of the state of the opening 18a of the anode mask 18, and the positions of the mask members 181 and 183 may be smoothly adjustable. The mask members 181 and 183 may be manually moved. The plating unit 10 may also include a moving mechanism (not shown) for moving the mask members 181 and 183. The movement mechanism may be a known mechanism, for example, a motor and a ball screw.

[0026] The mask members 182 and 184, which define the short sides of the opening 18a, have side portions 182a and 184a that align with the short sides of the substrate Wf. In this embodiment, the opening sides defined by the mask members 182 and 184 are straight and smooth. However, this is not limited to this example, and the opening sides defined by the mask members 182 and 184 may have irregularities. The mask members 182 and 184 may be configured so that the distance between them is adjustable. For example, the mask members 182 and 184 may be configured so that they are equally spaced from a position corresponding to the center of the anode 12. As shown in FIGS. 4 and 5, the mask members 182 and 184 may be positioned so that the greater the distance between the mask members 181 and 183, the closer they are to each other, and the closer the distance between the mask members 181 and 183, the farther they are from each other. It is preferable that the positions of the mask members 182 and 184 be smoothly variable, similar to the mask members 181 and 183. The mask members 182 and 184 may be configured to be moved manually, similar to the mask members 181 and 183, or may be configured to be movable by a movement mechanism (not shown).

[0027] As described above, the anode mask 18 includes first and second mask members (e.g., mask members 181 and 183) that define opening edges corresponding to the opposing first and second edges (e.g., side edges) of the substrate Wf with which the electrical contacts 34 come into contact. The first and second mask members 181 and 183 have recesses 181b and 183b formed in the centers of the opening edges that define the opening 18a, respectively, so that the opening 18a widens. The first and second mask members 181 and 183 are configured so that the distance between them can be adjusted. The anode mask 18 also includes third and fourth mask members (e.g., mask members 182 and 184) that define opening edges corresponding to the third and fourth edges (e.g., upper and lower edges) of the substrate Wf that are perpendicular to the first and second edges. The third mask member 182 and the fourth mask member 184 define straight opening sides corresponding to the third and fourth sides of the substrate Wf. The third mask member 182 and the fourth mask member 184 are configured so that the distance between them can be adjusted.

[0028] By configuring the anode mask 18 in this manner, the shape of the opening 18a in the anode mask 18 can be adjusted by moving the mask members 181-184. Here, the inventors have found that when electrical contacts are arranged on the peripheral edges of a pair of opposing sides of a rectangular substrate as shown in FIG. 3 , the plating film thickness tends to be thicker near the vertices of the substrate and thinner near the center of the sides where the electrical contacts do not come into contact. In the anode mask 18 of this embodiment, recesses 181b and 183b are formed in the mask members 181 and 183, so that the amount of shielding is greater near the corners of the opening 18a and smaller near the center of the opening side. The anode mask 18 having such an opening shape can improve the in-plane uniformity of the film plated on the substrate. The dimensions and shape of the recesses 181b and 183b in the mask members 181 and 183 may be appropriately determined through experiments, simulations, or the like to improve the in-plane uniformity of the plating film. Furthermore, the control device 17 of the plating device may control the movement mechanism so that the shape of the openings in the anode mask 18 is changed during plating.

[0029] FIG. 6 is a schematic diagram showing the plating film thickness on a rectangular substrate when a conventional anode mask of a comparative example is used, and FIG. 7 is a schematic diagram showing the plating film thickness on a rectangular substrate when the anode mask of this embodiment is used. In FIG. 6, an anode mask having an opening of the same shape as the substrate Wf is used. Furthermore, in FIGS. 6 and 7, lighter colors indicate a larger film thickness relative to the average film thickness, while darker colors indicate a smaller film thickness relative to the average film thickness. As shown in FIG. 6, with the conventional plating apparatus of the comparative example, the film thickness is larger, particularly above and below the edges of the substrate Wf where electrical contacts come into contact (the right and left edges in FIG. 6), i.e., near the corners of the substrate Wf, and smaller near the centers of the edges where electrical contacts do not come into contact (the top and bottom edges in FIG. 6). In contrast, as shown in FIG. 7, plating using the plating apparatus of this embodiment achieved better in-plane uniformity than the comparative example.

[0030] The present invention can also be described as the following embodiments. [Embodiment 1] According to embodiment 1, a plating apparatus is proposed, comprising: a plating tank; a substrate holder configured to hold a rectangular substrate, the substrate holder having electrical contacts configured to supply power to opposing first and second sides of the rectangular substrate; an anode disposed in the plating tank facing the rectangular substrate held by the substrate holder; and an anode mask defining an opening corresponding to the outer shape of the rectangular substrate, the anode mask including a first mask member defining a first recess so that the opening extends to a center of a first opening edge corresponding to the first side of the rectangular substrate; and a second mask member defining a second recess so that the opening extends to a center of a second opening edge corresponding to the second side of the rectangular substrate, the anode mask being configured so that the distance between the first mask member and the second mask member can be adjusted. According to embodiment 1, the in-plane uniformity of a film plated on a rectangular substrate can be improved.

[0031] [Mode 2] According to Mode 2, in Mode 1, the anode mask further includes a third mask member and a fourth mask member that face each other and define the other opening sides of the opening other than the first opening side and the second opening side.

[0032] [Mode 3] According to Mode 3, the third mask member and the fourth mask member in Mode 2 are configured so that the distance between them can be adjusted. According to Mode 3, it is possible to further improve the in-plane uniformity of the film plated on the rectangular substrate.

[0033] [Form 4] According to form 4, in form 2 or 3, the third mask member and the fourth mask member define straight opening sides corresponding to the third side and the fourth side that are perpendicular to the first side and the second side of the rectangular substrate.

[0034] [Mode 5] According to Mode 5, in any of Modes 1 to 4, the first recess and the second recess have a trapezoidal shape that becomes thinner as it gets further away from the center of the opening.

[0035] [Mode 6] According to Mode 6, in any of Modes 1 to 5, the first mask member is arranged on the first opening side and configured to be movable in a direction perpendicular to the first opening side, and the second mask member is arranged on the second opening side and configured to be movable in a direction perpendicular to the second opening side. According to Mode 6, the distance between the first mask member and the second mask member can be adjusted by moving them.

[0036] [Mode 7] According to Mode 7, there is proposed a method for plating a rectangular substrate by passing a current between an anode and a polygonal substrate in a plating apparatus, the plating method including: an anode mask defining an opening corresponding to the outer shape of the rectangular substrate, the anode mask having a first mask member defining a first recess so that the opening extends to a center of a first opening edge corresponding to a first side of the rectangular substrate in the opening; and a second mask member defining a second recess so that the opening extends to a center of a second opening edge corresponding to a second side of the rectangular substrate opposite the first side of the rectangular substrate in the opening; adjusting the distance between the first mask member and the second mask member; holding the rectangular substrate with a substrate holder having electrical contacts configured to supply power to the first side and the second side of the rectangular substrate; and passing a current between the anode and the polygonal substrate. According to Mode 7, the in-plane uniformity of a film plated on the rectangular substrate can be improved.

[0037] [Mode 8] According to Mode 8, as in Mode 7, the anode mask further includes a third mask member and a fourth mask member facing each other and defining the other opening side of the opening other than the first opening side and the second opening side, and the plating method includes adjusting the distance between the third mask member and the fourth mask member so that the closer the distance between the first mask member and the second mask member, the farther the third mask member and the fourth mask member become. According to Mode 8, it is possible to further improve the in-plane uniformity of the film plated on the rectangular substrate.

[0038] Although the embodiments of the present invention have been described above, the above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention naturally includes equivalents thereof. Furthermore, any combination or omission of the components described in the claims and specification is possible within the scope of solving at least part of the above-described problems or achieving at least part of the effects.

[0039] DESCRIPTION OF SYMBOLS 10... Plating unit 12... Anode 13... Anode holder 17... Control device 18... Anode mask 18a... Opening 20... Regulation plate 30... Substrate holder 34... Electrical contact 36... Power supply contact 181 to 184... Mask member 181a to 184a... Side portion 181b, 183b... Recess Wf... Rectangular substrate

Claims

1. A plating apparatus comprising: a plating tank; a substrate holder configured to hold a rectangular substrate, the substrate holder having electrical contacts configured to supply power to opposing first and second sides of the rectangular substrate; an anode arranged in the plating tank so as to face the rectangular substrate held by the substrate holder; and an anode mask defining an opening corresponding to the outline of the rectangular substrate, the anode mask having: a first mask member defining a first recess so that the opening extends to a center of a first opening side of the opening corresponding to the first side of the rectangular substrate; and a second mask member defining a second recess so that the opening extends to a center of a second opening side of the opening corresponding to the second side of the rectangular substrate, the anode mask being configured so that the distance between the first mask member and the second mask member can be adjusted.

2. The plating apparatus of claim 1, wherein the anode mask further comprises a third mask member and a fourth mask member facing each other and defining the other opening sides of the opening other than the first opening side and the second opening side.

3. The plating apparatus according to claim 2, wherein the third mask member and the fourth mask member are configured so that the distance between them can be adjusted.

4. The plating apparatus of claim 2, wherein the third mask member and the fourth mask member define straight opening sides corresponding to third and fourth sides perpendicular to the first and second sides of the rectangular substrate.

5. A plating apparatus according to any one of claims 1 to 4, wherein the first recess and the second recess have a trapezoidal shape that becomes narrower as they move away from the center of the opening.

6. A plating apparatus as described in any one of claims 1 to 4, wherein the first mask member is arranged on the first opening edge and configured to be movable in a direction perpendicular to the first opening edge, and the second mask member is arranged on the second opening edge and configured to be movable in a direction perpendicular to the second opening edge.

7. A method for plating a rectangular substrate in a plating apparatus by passing a current between the anode and the rectangular substrate, the method comprising: an anode mask defining an opening corresponding to the outline of the rectangular substrate, the anode mask having a first mask member defining a first recess so that the opening extends to a center of a first opening edge of the opening corresponding to a first edge of the rectangular substrate; and a second mask member defining a second recess so that the opening extends to a center of a second opening edge of the opening corresponding to a second edge of the rectangular substrate opposite the first edge, adjusting the distance between the first mask member and the second mask member; holding the rectangular substrate with a substrate holder having electrical contacts configured to supply power to the first edge and the second edge of the rectangular substrate; and passing a current between the anode and the polygonal substrate.

8. The plating method according to claim 7, wherein the anode mask further comprises a third mask member and a fourth mask member facing each other and defining the other opening side of the opening other than the first opening side and the second opening side, and the plating method includes adjusting the distance between the third mask member and the fourth mask member so that the closer the distance between the first mask member and the second mask member, the farther the third mask member and the fourth mask member are.

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