RESISTOR AND PLATING APPARATUS

TECHNICAL FIELD

The present invention relates to a resistor and a plating apparatus.

BACKGROUND ART

Conventionally, a wiring, a bump (protruding electrode) and the like are formed on a substrate surface of a semiconductor wafer, a printed circuit board or the like. An electroplating method is known as a method of forming this wiring, bump or the like.

In a plating apparatus by the electroplating method, it is known that a resistor for adjusting an electric field, having a large number of holes between a circular substrate such as a wafer and an anode, is disposed (see PTL 1, for example).

Further, a cup type electroplating apparatus is known as an example of a plating apparatus (see PTL 2, for example). In the cup type electroplating apparatus, a substrate (e.g., a semiconductor wafer) held by a substrate holder with a surface to be plated being oriented downward is immersed into a plating solution, and a voltage is applied between the substrate and an anode, thereby precipitating a conductive film on a substrate surface. In the cup type plating apparatus, the substrate is subjected to a plating treatment while rotating the substrate so that a plating layer is uniformly formed on the substrate.

CITATION LIST
Patent Literature

- PTL 1: Japanese Patent Laid-Open No. 2004-225129
- PTL 2: Japanese Patent Laid-Open No. 2008-19496

SUMMARY OF INVENTION
Technical Problem

Also, in a cup type electroplating apparatus, it is considered that a punching plate having a large number of holes is provided as a resistor for adjusting an electric field. In this case, the electric field adjustment can be suitably performed by forming a large number of holes on a plurality of reference true circles concentric with the resistor. However, through studies by the present inventors, it has been found that when the resistor formed in this way is used, film thickness uniformity in the vicinity of an outer peripheral portion of a wafer may be low. This is considered to be, for example, due to accuracy in forming the large number of holes, dimensional accuracy of a plating tank, or the like.

One of objects of the present invention, which has been made in view of the above problems, is to provide a resistor and a plating apparatus that can improve uniformity of a plating film formed on a substrate.

Solution to Problem

According to one embodiment of the present invention, a resistor disposed between a substrate and an anode in a plating tank is provided. The resistor includes a first plurality of holes each formed on three or more reference circles being concentric and having different diameters and a second plurality of holes formed on an outer circumferential reference line surrounding the three or more reference circles, at least a part of the outer circumferential reference line being a trochoid curve.

According to another embodiment of the present invention, a plating apparatus is provided. The plating apparatus includes the resistor and a plating tank that houses the resistor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing an overall configuration of a plating apparatus of the present embodiment;

FIG. 2 is a plan view showing the overall configuration of the plating apparatus of the present embodiment;

FIG. 3 is a longitudinal sectional view schematically showing a configuration of a plating module of the present embodiment;

FIG. 4 is a plan view schematically showing a resistor of the present embodiment;

FIG. 5 is a schematic view for explaining a plurality of holes formed in the resistor of the present embodiment;

FIG. 6 shows a second example of the plurality of holes formed in the resistor;

FIG. 7 shows a third example of the plurality of holes formed in the resistor;

FIG. 8 shows a fourth example of the plurality of holes formed in the resistor;

FIG. 9 shows a fifth example of the plurality of holes formed in the resistor; and

FIG. 10 is a view showing a modification of an outer circumferential reference line.

DESCRIPTION OF EMBODIMENTS

Hereinafter, description will be made as to embodiments of the present invention with reference to the drawings. In the drawings illustrated below, the same or corresponding constituent component is denoted with the same reference sign, and redundant description will not be repeated.

FIG. 1 is a perspective view showing an overall configuration of a plating apparatus of the present embodiment. FIG. 2 is a plan view showing the overall configuration of the plating apparatus of the present embodiment. The plating apparatus of the present embodiment is for use in subjecting a substrate to a plating treatment. Examples of the substrate include a square substrate and a circular substrate. As shown in FIGS. 1 and 2, a plating apparatus 1000 includes a loading/unloading module 100, a transfer robot 110, an aligner 120, a prewetting module 200, a presoaking module 300, a plating module 400, a washing module 500, a spin rinse dryer module 600, a transfer device 700, and a control module 800.

The loading/unloading module 100 is a module for loading a substrate such as a semiconductor wafer into the plating apparatus 1000 and unloading the substrate from the plating apparatus 1000, and a cassette for housing the substrate is mounted on the module. In the present embodiment, four loading/unloading modules 100 are arranged in a horizontal direction, but the number and arrangement of the loading/unloading modules 100 are arbitrary. The transfer robot 110 is a robot for transferring the substrate and configured to deliver the substrate among the loading/unloading module 100, the aligner 120, and the transfer device 700. The transfer robot 110 and the transfer device 700 can deliver the substrate via an unshown temporary stand, when delivering the substrate between the transfer robot 110 and the transfer device 700. The aligner 120 is a module for aligning positions of an orientation flat, a notch and the like of the substrate in a predetermined direction. In the present embodiment, two aligners 120 are arranged in the horizontal direction, but the number and arrangement of the aligners 120 are arbitrary.

The prewetting module 200 is a module for adhering a treatment liquid (prewetting liquid) such as pure water or de-aired water to a surface to be plated of the substrate prior to the plating treatment. In the present embodiment, two prewetting modules 200 are arranged in an up-down direction, but the number and arrangement of the prewetting modules 200 are arbitrary. The presoaking module 300 is a module for etching an oxide film on the surface to be plated of the substrate prior to the plating treatment. In the present embodiment, two presoaking modules 300 are arranged in the up-down direction, but the number and arrangement of the presoaking modules 300 are arbitrary.

The plating module 400 is a module for subjecting the substrate to the plating treatment. In the present embodiment, there are two sets of twelve plating modules 400, each set including three plating modules arranged in the up-down direction and four plating modules arranged in the horizontal direction, and 24 plating modules 400 in total are provided. The number and arrangement of the plating modules 400 are arbitrary.

The washing module 500 is a module for washing the substrate subjected to the plating treatment. In the present embodiment, two washing modules 500 are arranged in the up-down direction, but the number and arrangement of the washing modules 500 are arbitrary. The spin rinse dryer module 600 is a module for rotating the substrate subjected to a washing treatment at a high speed to dry the substrate. In the present embodiment, two spin rinse dryer modules are arranged in the up-down direction, but the number and arrangement of the spin rinse dryer modules are arbitrary.

The transfer device 700 is a device for transferring the substrate among a plurality of modules in the plating apparatus 1000. The control module 800 is a module for controlling the plurality of modules of the plating apparatus 1000 and may include a general computer or a dedicated computer including, for example, an input/output interface between the computer and an operator.

An example of a series of plating treatment by the plating apparatus 1000 will be described. First, the substrate is loaded into the loading/unloading module 100. Subsequently, the transfer robot 110 removes the substrate from the loading/unloading module 100 and transfers the substrate to the aligner 120. The aligner 120 aligns the positions of the orientation flat, notch and the like in the predetermined direction. The transfer robot 110 delivers, to the transfer device 700, the substrate aligned in the direction by the aligner 120.

The transfer device 700 transfers, to the prewetting module 200, the substrate received from the transfer robot 110. The prewetting module 200 subjects the substrate to a prewetting treatment. The transfer device 700 transfers, to the presoaking module 300, the substrate subjected to the prewetting treatment. The presoaking module 300 subjects the substrate to a presoaking treatment. The transfer device 700 transfers, to the plating module 400, the substrate subjected to the presoaking treatment. The plating module 400 subjects the substrate to the plating treatment.

The transfer device 700 transfers, to the washing module 500, the substrate subjected to the plating treatment. The washing module 500 subjects the substrate to the washing treatment. The transfer device 700 transfers the substrate subjected to the washing treatment to the spin rinse dryer module 600. The spin rinse dryer module 600 subjects the substrate to a drying treatment. The transfer device 700 delivers the substrate subjected to the drying treatment to the transfer robot 110. The transfer robot 110 transfers the substrate received from the transfer device 700 to the loading/unloading module 100. Finally, the substrate is unloaded from the loading/unloading module 100.

Next, a configuration of the plating module 400 will be described. The 24 plating modules 400 in the present embodiment have the same configuration, and hence one plating module 400 will only be described. FIG. 3 is a longitudinal sectional view schematically showing the configuration of the plating module 400 of the present embodiment. As shown in FIG. 3, the plating module 400 includes a plating tank 410 for storing a plating solution. The plating tank 410 includes a cylindrical inner tank 412 having an opened upper surface, and an unshown outer tank disposed around the inner tank 412 to accumulate the plating solution that overflows from an upper edge of the inner tank 412.

The plating module 400 includes a substrate holder 440 for holding a substrate Wf in a state where a surface to be plated Wf-a is oriented downward. Furthermore, the substrate holder 440 includes a power supply contact point that supplies power from an unshown power source to the substrate Wf. The plating module 400 includes an elevating/lowering mechanism 442 for elevating and lowering the substrate holder 440. Also, in one embodiment, the plating module 400 includes a rotating mechanism 448 that rotates the substrate holder 440 about a vertical axis. The elevating/lowering mechanism 442 and the rotating mechanism 448 can be achieved with a known mechanism such as a motor.

The plating module 400 includes a membrane 420 that separates an interior of the inner tank 412 in the up-down direction. The interior of the inner tank 412 is separated into a cathode region 422 and an anode region 424 by the membrane 420. Each of the cathode region 422 and the anode region 424 is filled with the plating solution. Note that in the present embodiment, an example where the membrane 420 is provided has been described, but the membrane 420 does not have to be provided.

An anode 430 is disposed on a bottom surface of the inner tank 412 of the anode region 424. Also, in the anode region 424, an anode mask 426 for adjusting an electric field between the anode 430 and the substrate Wf is disposed. The anode mask 426 is a substantially plate-shaped member formed of, for example, a dielectric material, and is provided on a front surface of (above) the anode 430. The anode mask 426 includes an opening through which current flowing between the anode 430 and the substrate Wf passes. In the present embodiment, an example where the anode mask 426 is provided has been described, but the anode mask 426 does not have to be provided. Furthermore, the membrane 420 does not have to be disposed in the opening of the anode mask 426.

In the cathode region 422, a resistor 450 facing the membrane 420 is disposed. The resistor 450 is a member for uniformly performing the plating treatment in the surface to be plated Wf-a of the substrate Wf. FIG. 4 is a plan view schematically showing the resistor of the present embodiment. Note that FIG. 4 also shows an enlarged part of the resistor for ease of understanding. Further, an example shown in FIG. 4 corresponds to an after-mentioned fifth example (FIG. 9). As shown in FIG. 4, the resistor 450 includes a plurality of holes 452 and 454. The holes 452 and 454 penetrate between a front surface and a back surface of the resistor 450 and form a path through which the plating solution and ions in the plating solution pass. In the resistor 450 according to the present embodiment, a first plurality of holes 452 and a second plurality of holes 454 are formed.

The first plurality of holes 452 are arranged on three or more virtual reference circles (see a dashed chain line in FIG. 4) that are concentric and have different diameters. In other words, the first plurality of holes 452 are arranged to disperse in a radial direction of the resistor 450. The first plurality of holes 452 are preferably arranged at equal intervals along a circumferential direction on the reference circle. Consequently, the holes 452 can be arranged to disperse along the circumferential direction of the reference circle. In the resistor 450, it is preferable that a difference between a diameter of an arbitrary reference circle and a diameter of a reference circle adjacent to the arbitrary reference circle is constant. In other words, the holes 452 are preferably arranged at equal intervals in the radial direction. Consequently, the holes 452 can be arranged to disperse along the radial direction of the reference circle. In one embodiment, each of the first plurality of holes 452 is truly circular as seen from a top surface. The first plurality of holes 452 may have the same dimension as each other. Note that in this specification, “equal intervals” and “same” are not limited to mathematically perfect equal intervals and may include some deviations caused by errors in machining or the like.

The second plurality of holes 454 are arranged on an outer circumferential side of the first plurality of holes 452. Specifically, the second plurality of holes 454 are formed on an outer circumferential reference line (see a double-dashed chain line in FIG. 4) surrounding the reference circles in which the first plurality of holes 452 are arranged. Here, in the present embodiment, the outer circumferential reference line is a trochoid curve. Through studies by the present inventors, it has been found that when the second plurality of holes 454 on the outer circumferential side are arranged on the outer circumferential reference line, at least a part of which is the trochoid curve, uniformity of a plating film formed on the substrate Wf in the plating module 400 can be improved.

FIG. 5 is a schematic view for explaining a plurality of holes formed in the resistor of the present embodiment. In FIG. 5, an upper part shows, as a comparative example, an example where the second plurality of holes 454 are arranged on a reference circle that is a true circle (see a dashed line in FIG. 5, hereinafter referred to as “the reference circle”). Further, a lower part of FIG. 5 shows, as a first example of a plurality of holes formed in the resistor, an example where the second plurality of holes 454 are arranged on an outer circumferential reference line that is a trochoid curve (see a double-dashed chain line in FIG. 5). As shown in the lower part of FIG. 5, the outer circumferential reference line can be a trochoid curved drawn by a predetermined fixed point of a predetermined moving circle when moving the moving circle along an inner circumference of the reference circle. However, the outer circumferential reference line is not limited to such an example and may be a trochoid curve drawn by the predetermined fixed point of the predetermined moving circle, when moving the moving circle along an outer circumference of the reference circle. Here, as an example, the moving circle may be defined to make 7 turns (2520° turns) when traveling around the reference circle.

FIG. 6 shows a second example of the plurality of holes formed in the resistor. As shown in FIG. 6, a second plurality of holes 454 may not be formed in a region where a distance from a first plurality of holes 452 is small to an outer circumferential reference line that is a trochoid curve (a hatched region in FIG. 6, which is also referred to as a “predetermined region”). As an example, the predetermined region is a region where a distance between the outer circumferential reference line and a reference circle of the first plurality of holes 452 is less than a predetermined threshold. According to the second example, a distance between the first plurality of holes 452 and the second plurality of holes 454 cannot be excessively small, and an opening ratio can be inhibited from being excessively large in the predetermined region. In the above first example (FIG. 5), for ease of understanding, the first plurality of holes 452 and the second plurality of holes 454 partially overlap with each other, but the example is exaggeratedly illustrated, and it is preferable that the first plurality of holes 452 and the second plurality of holes 454 do not overlap each other.

FIG. 7 shows a third example of the plurality of holes formed in the resistor. In the region where the plurality of second holes 454 are not formed in the above second example (FIG. 6) (a hatched region in FIG. 7, which will be referred to also as a “predetermined region”), in the third example, a first plurality of holes 452 are larger than holes 452 in another region. Specifically, in the third example, a diameter ra of each of the first plurality of holes 452 in the predetermined region is larger than a diameter rb of each of the first plurality of holes 452 outside the predetermined region. According to such an example, an opening ratio of the resistor near a boundary of the predetermined region can be inhibited from being rapidly changed, and uniformity of a plating film formed on a substrate Wf can be improved.

FIG. 8 shows a fourth example of the plurality of holes formed in the resistor. As shown in FIG. 8, a second plurality of holes 454 may be long holes that are long in a circumferential direction. In this case, as an example, the second plurality of holes 454 may be long holes each having a length increasing along the circumferential direction as being arranged away from a first plurality of holes 452 (or a reference circle of the holes). Thus, at least some of the second plurality of holes 454 are the long holes, so that change in opening ratio along an outer circumferential reference line can be reduced, and uniformity of a plating film formed on a substrate Wf can be improved. In the example shown in FIG. 8, as in the above second example (FIG. 6), the second plurality of holes 454 are not formed in a region (predetermined region) close to the first plurality of holes 452 but are not limited to this example.

FIG. 9 shows a fifth example of the plurality of holes formed in the resistor. In the fifth example shown in FIG. 9, as in the fourth example (FIG. 8), a second plurality of holes 454 are long holes that are long in a circumferential direction. Further, in the fifth example shown in FIG. 9, as in the third example (FIG. 7), the second plurality of holes 454 are not formed, and a first plurality of holes 452 are enlarged, in a predetermined region. According to such an example, an opening ratio of the resistor can be smoothly changed, and uniformity of a plating film formed on a substrate Wf can be improved.

Here, the plating treatment in the plating module 400 of the present embodiment will be described in more detail. The substrate Wf is exposed to the plating solution by immersing the substrate Wf in the plating solution of the cathode region 422 using the elevating/lowering mechanism 442. By applying a voltage between the anode 430 and the substrate Wf in this state, the plating module 400 can subject the surface to be plated Wf-a of the substrate Wf to the plating treatment. In one embodiment, the plating treatment is performed while rotating the substrate holder 440 using the rotating mechanism 448. Through the plating treatment, a conductive film (plating film) is precipitated on the surface to be plated Wf-a of the substrate Wf. Then, in the present embodiment, the resistor 450 is adopted, so that a density of the holes formed in the above resistor 450 is uniform, and the uniformity of the plating film formed on the substrate can be improved.

(Modification)

In the above embodiment, it has been described that an outer circumferential reference line on which the second plurality of holes 454 are formed is the trochoid curve. However, at least a part of the outer circumferential reference line may only be a trochoid curve, and in an example shown in FIG. 10, the outer circumferential reference line may be a line (see a thick line in FIG. 10) including Boolean sum of two trochoid curves with opposite displacement phases (unevenness) with respect to a fixed circle (see a dashed chain line C1 and a double-dashed chain line C2 in FIG. 10). Also, in this case, the two trochoid curves may be curves including the same fixed circle as each other and different radiuses of moving circles. In the two trochoid curves, the moving circle can be defined to make 7 turns (2520° turns) when traveling around the reference circle.

The present invention can be described in aspects as follows.

[Aspect 1]

According to Aspect 1, a resistor disposed between a substrate and an anode in a plating tank is provided, the resistor including a first plurality of holes each formed on three or more reference circles being concentric and having different diameters and a second plurality of holes formed on an outer circumferential reference line surrounding the three or more reference circles, at least a part of the outer circumferential reference line being a trochoid curve.

According to Aspect 1, uniformity of a plating film formed on the substrate can be improved when the resistor is used in a plating apparatus.

[Aspect 2]

According to Aspect 2, in Aspect 1, at least some of the second plurality of holes are long holes that are long along a circumferential direction.

According to Aspect 2, the uniformity of the plating film formed on the substrate can be further improved when the resistor is used in the plating apparatus.

[Aspect 3]

According to Aspect 3, in Aspect 2, the long holes have a length increasing along the circumferential direction as being formed in a region away from the three or more reference circles.

According to Aspect 3, the uniformity of the plating film formed on the substrate can be further improved when the resistor is used in the plating apparatus.

[Aspect 4]

According to Aspect 4, in Aspects 1 to 3, the second plurality of holes are not formed in a predetermined region where a distance between the reference circle of an outermost circumference in the three or more reference circles and the outer circumferential reference line is less than a first distance.

According to Aspect 4, the uniformity of the plating film formed on the substrate can be further improved when the resistor is used in the plating apparatus.

[Aspect 5]

According to Aspect 5, in Aspect 4, in the predetermined region, the first plurality of holes formed in the reference circle of the outermost circumference are larger than the first plurality of holes formed in the reference circle of the outermost circumference that is not in the predetermined region.

According to Aspect 5, the uniformity of the plating film formed on the substrate can be further improved when the resistor is used in the plating apparatus.

[Aspect 6]

According to Aspect 6, in Aspects 1 to 5, the first plurality of holes are arranged at equal intervals along a circumferential direction on the reference circles.

[Aspect 7]

According to Aspect 7, in Aspects 1 to 6, the first plurality of holes have the same dimension except for at least holes formed on the reference circle of an outermost circumference in the three or more reference circles.

[Aspect 8]

According to Aspect 8, in Aspects 1 to 7, a difference between a diameter of an arbitrary reference circle and a diameter of a reference circle adjacent to the arbitrary reference circle is constant.

[Aspect 9]

According to Aspect 9, a plating apparatus including the resistor according to any one of Aspects 1 to 8 and a plating tank that houses the resistor is provided.

According to Aspect 9, the uniformity of the plating film formed on the substrate can be further improved.

[Aspect 10]

According to Aspect 10, in Aspect 9, the plating apparatus further includes a substrate holder holding a substrate and a rotating mechanism that rotates the substrate holder.

The embodiments of the present invention have been described above, but the above embodiments of the present invention are described to facilitate understanding of the present invention and are not intended to limit the present invention. Needless to say, the present invention may be changed or modified without departing from the spirit, and the present invention includes equivalents to the invention. Also, in a range in which at least some of the above-described problems can be solved or a range in which at least some of effects are exhibited, any arbitrary combination of the embodiments and the modification is possible, and arbitrary combination or omission of respective constituent components described in claims and description is possible.

REFERENCE SIGNS LIST

- 400 plating module
- 410 plating tank
- 420 membrane
- 422 cathode region
- 424 anode region
- 430 anode
- 440 substrate holder
- 442 elevating/lowering mechanism
- 448 rotating mechanism
- 450 resistor
- 452 first plurality of holes
- 454 second plurality of holes
- 800 control module
- 1000 plating apparatus
- Wf substrate

RESISTOR AND PLATING APPARATUS

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