NICKEL-PLATING STACK, SEMICONDUCTOR DEVICE, MANUFACTURING APPARATUS FOR NICKEL-PLATING STACK, METHOD OF MANUFACTURING NICKEL-PLATING STACK, AND METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This nonprovisional application is based on Japanese Patent Application No. 2024-085311 filed on May 27, 2024 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a nickel-plating stack, a semiconductor device, a manufacturing apparatus for a nickel-plating stack, a method of manufacturing a nickel-plating stack, and a method of manufacturing a semiconductor device.

Description of the Background Art

Conventionally, there has been known a method of manufacturing a nickel-plating stack, wherein a nickel-plating stack is formed on a plating-target member by immersing the plating-target member in a nickel plating solution. The nickel-plating stack is formed by a nickel layer including phosphorus. The plating-target member immersed in the nickel plating solution is removed and is immersed in another nickel plating solution having a different phosphorus concentration, thereby further forming a nickel layer having a different phosphorus concentration. However, when the plating-target member is removed from the nickel plating solution, an oxide film may be formed between the nickel layers. In Japanese Patent Laying-Open No. 2017-128791, two nickel layers having different phosphorus concentrations are formed by changing a condition (concentration, temperature, or the like) of a nickel plating solution without removing a plating-target member from the nickel plating solution.

SUMMARY OF THE INVENTION

However, in the above-described conventional method, it is difficult to change a phosphorus concentration a plurality of times among the plurality of nickel layers. Therefore, in the conventional method, there is room for improvement in changing a phosphorus concentration among the plurality of nickel layers.

The present disclosure has been made to solve the above-described problem, and has an object to provide a nickel-plating stack, a semiconductor device, a manufacturing apparatus for a nickel-plating stack, a method of manufacturing a nickel-plating stack, and a method of manufacturing a semiconductor device, so as to readily change a phosphorus concentration among a plurality of nickel layers.

A method of manufacturing a nickel-plating stack according to the present disclosure includes: preparing a nickel plating solution including phosphorus and a sulfur additive, and a plating-target member; and forming a nickel-plating stack on the plating-target member using the nickel plating solution. The nickel-plating stack includes nickel layers having different phosphorus concentrations.

A method of manufacturing a semiconductor device according to the present disclosure uses the above-described method of manufacturing a nickel-plating stack. The plating-target member includes a semiconductor base member.

A manufacturing apparatus for a nickel-plating stack according to the present disclosure includes a container and at least one of a convection mechanism and a shaking mechanism. The container accommodates a nickel plating solution. The convection mechanism causes convection of the nickel plating solution. The shaking mechanism shakes the plating-target material.

A nickel-plating stack according to the present disclosure include at least three or more nickel layers. Two nickel layers having different phosphorus concentrations among the nickel layers are disposed in direct contact with each other.

A semiconductor device according to the present disclosure includes: the nickel-plating stack; and a connection member. A recess is provided in the nickel-plating stack. The nickel-plating stack and the connection member are connected by the recess.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of a nickel-plating stack according to a first embodiment.

FIG. 2 is a schematic diagram of a manufacturing apparatus for a nickel-plating stack according to the first embodiment.

FIG. 3 is a schematic diagram of a modification of the manufacturing apparatus for a nickel-plating stack according to the first embodiment.

FIG. 4 is a flowchart of a method of manufacturing a nickel-plating stack according to the first embodiment.

FIG. 5 is a schematic cross sectional view of a semiconductor device according to a second embodiment.

FIG. 6 is a schematic cross sectional view of a nickel-plating stack according to a third embodiment.

FIG. 7 is a schematic diagram illustrating a shielding effectiveness.

FIG. 8 is a schematic partial enlarged cross sectional view of a nickel-plating stack according to a fourth embodiment.

FIG. 9 is a flowchart of a method of manufacturing a nickel-plating stack according to a fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described. It should be noted that in the below-described figures, the same or corresponding portions are denoted by the same reference characters and will not be described repeatedly, unless stated otherwise particularly.

First Embodiment

<Configuration of Nickel-Plating Stack>

FIG. 1 is a schematic cross sectional view of a nickel (Ni) plating stack 2 according to a first embodiment. Nickel-plating stack 2 shown in FIG. 1 is, for example, a nickel-plating stack 2 formed on a plating-target member 1, and includes at least three or more nickel layers 20.

Plating-target member 1 may be any member. Plating-target member 1 may be a semiconductor substrate of a semiconductor device. Plating-target member 1 may include a semiconductor base member 11 and a wiring layer 12 as described later (see FIG. 5). Nickel-plating stack 2 may be disposed on wiring layer 12 (see FIG. 5).

As shown in FIG. 1, nickel-plating stack 2 is constituted of the plurality of nickel layers 20. Nickel-plating stack 2 may be constituted of three or more nickel layers 20, may be constituted of five or more nickel layers 20, or may be constituted of ten or more nickel layers 20.

As described below, each of nickel layers 20 is formed using a nickel (Ni) plating solution including phosphorus (P). That is, nickel layer 20 includes phosphorus. Two nickel layers 20 disposed adjacent to each other have different phosphorus concentrations. No oxide film is formed between the plurality of nickel layers 20. That is, the two nickel layers disposed adjacent to each other are disposed in direct contact with each other.

Specifically, the plurality of nickel layers 20 include a first layer 21, a second layer 22, and a third layer 23. First layer 21 is adjacent to second layer 22. Third layer 23 is adjacent to second layer 22. Third layer 23 is disposed in a region opposite to a region in which first layer 21 is disposed when viewed from second layer 22. That is, first layer 21, second layer 22, and third layer 23 are stacked in this order.

No oxide film is formed between first layer 21 and second layer 22. That is, first layer 21 is in direct contact with second layer 22. No oxide film is formed between second layer 22 and third layer 23. That is, second layer 22 is in direct contact with third layer 23.

A phosphorus concentration in first layer 21 is different from a phosphorus concentration in second layer 22. Moreover, the phosphorus concentration in second layer 22 is different from a phosphorus concentration in third layer 23. The phosphorus concentration in first layer 21 may be more than or less than the phosphorus concentration in second layer 22. The phosphorus concentration in second layer 22 may be more than or less than the phosphorus concentration in third layer 23. Thus, the phosphorus concentrations in adjacent nickel layers 20 are different from each other.

A combination of nickel layers 20 to be stacked may be changed in accordance with properties of nickel layers 20 corresponding to the phosphorus concentrations. Table 1 shows physical properties of each of a low phosphorus layer, a medium phosphorus layer, and a high phosphorus layer. From the top, Table 1 shows phosphorus concentration, crystal state, magnetic property, saltwater resistance spray time (unit: Hr), acid resistance, hardness (Vickers hardness) before heat treatment, hardness (Vickers hardness) after heat treatment, coefficient of thermal expansion, electrical resistivity, internal stress, wear resistance, and solder wettability. The hardness after heat treatment indicates hardness after performing heat treatment at 400° C. for one hour. The wear resistance is represented by an indicator indicated by the Test Wear Index (TWI). The TWI indicates resistance of a material against mechanical effects such as friction and abrasion.

When the phosphorus concentration in nickel layer 20 is 1 mass % or more and 4 mass % or less, nickel layer 20 is the low phosphorus layer described in Table 1. When the phosphorus concentration in nickel layer 20 is 5 mass % or more and 8 mass % or less, nickel layer 20 is the medium phosphorus layer described in Table 1. When the phosphorus concentration in nickel layer 20 is 9 mass % or more and 12 mass % or less, nickel layer 20 is the high phosphorus layer described in Table 1.

It should be noted that in Table 1, A, B, and C represent evaluations on each of the acid resistance and the solder wettability. It is indicated that B is more excellent than C. It is indicated that A is more excellent than B. That is, it is indicated that A has the most excellent evaluation among A, B, and C. Moreover, the saltwater resistance spray time indicates a time to a stage at which a specific value is exceeded in a saltwater spray test. A degree of corrosion is evaluated through both appearance observation and mass-material measurement.

	TABLE 1
	Low Phosphorus	Medium Phosphorus	High Phosphorus
	Layer	Layer	Layer

Phosphorus Concentration (mass %)	1 to 4	5 to 8	9 to 12
Crystal State	Crystalline	Intermediate	Amorphous
Magnetic Property	High Magnetic	Intermediate	Non-Magnetic
	Property		Property
Saltwater Resistance Spray Time (Hr)	24	200	1000
Acid Resistance	C	B	A
Hardness Before Heat Treatment (Hv)	650 to 700	550 to 600	500 to 550
Hardness After Heat Treatment (Hv)	950 to 1000	1050 to 1100	1000 to 1050
Coefficient of Thermal Expansion	13 to 15	13 to 14.5	13.5
(μm/m/° C.)
Electrical Resistivity (μΩ/cm)	20 to 30	30 to 60	52 to 68
Internal Stress (MPa)	−10 to −100	+10 to 85	+10 to 31.7
(+: Tensile Stress; −: Compressive
Stress)
Wear Resistance (TWI)	10 to 20	15 to 20	20 to 25
Solder Wettability	A	B	C

Nickel-plating stack 2 may be a nickel-plating stack 2 in which the low phosphorus layer and the medium phosphorus layer are sequentially stacked. The low phosphorus layer has relatively inferior corrosion resistance, but the medium phosphorus layer has excellent corrosion resistance. Therefore, when the low phosphorus layer and the medium phosphorus layer are sequentially stacked, the corrosion resistance of the low phosphorus layer is complemented by the medium phosphorus layer. Moreover, each of the low phosphorus layer and the medium phosphorus layer has a magnetic property when heated.

Nickel-plating stack 2 may be a nickel-plating stack 2 in which the medium phosphorus layer and the high phosphorus layer are sequentially stacked. The medium phosphorus layer has relatively inferior solder wettability, but the high phosphorus layer has excellent solder wettability. Therefore, when the medium phosphorus layer and the high phosphorus layer are sequentially stacked, the solder wettability of the medium phosphorus layer is complemented by the high phosphorus layer. Moreover, the medium phosphorus layer has a magnetic property when heated. It should be noted that the high phosphorus layer does not have a magnetic property.

The thickness of each of nickel layers 20 may be, for example, 0.1 μm or more and 0.4 μm or less. The average value of thickness of each of nickel layers 20 in nickel-plating stack 2 may be 0.1 μm or more and 0.5 μm or less. The lower limit of the average value of thickness may be 0.15 μm or 0.2 μm. The upper limit of the average value of thickness may be 0.4 μm or 0.3 μm. The average value may be 0.23 μm, for example. The thickness of nickel-plating stack 2 (total thickness of nickel layers 20) may be 0.3 μm or more and 10 μm or less. The lower limit of the thickness may be 1 μm, 2 μm, 3 μm, or 4 μm. The upper limit of the thickness may be 8 μm, 6 μm, or 5 μm. The thickness may be, for example, 4.3 μm. Thus, since the thickness of each of nickel layers 20 is of a submicron level, internal stress of nickel-plating stack 2 is relaxed.

Thus, by forming nickel layers 20 having different phosphorus concentrations, a nickel-plating stack 2 to attain an effect corresponding to a purpose of use can be obtained. In particular, by forming three or more nickel layers 20 having different phosphorus concentrations, effects can be attained such as improvement in wear resistance, improvement in corrosion resistance, improvement in solder wettability, increase in hardness (Vickers hardness), and relaxation of stress.

<Manufacturing Apparatus for Nickel-Plating Stack>

Next, a manufacturing apparatus 100 for nickel-plating stack 2 according to the first embodiment will be described. FIG. 2 is a schematic diagram of manufacturing apparatus 100 for nickel-plating stack 2 according to the first embodiment. Nickel-plating stack 2 is formed using manufacturing apparatus 100 shown in FIG. 2. Manufacturing apparatus 100 for nickel-plating stack 2 includes a container 101, a convection mechanism 102, and a shaking mechanism 103. Manufacturing apparatus 100 may include at least one of convection mechanism 102 and shaking mechanism 103, and may include both convection mechanism 102 and shaking mechanism 103 as shown in FIG. 2.

Container 101 accommodates nickel (Ni) plating solution 200 and plating-target member 1. Nickel plating solution 200 is, for example, an electroless nickel plating solution and includes phosphorus (P) and a sulfur additive. The sulfur additive is, for example, thiocyanate hydrochloride or the like.

By immersing plating-target member 1 in nickel plating solution 200, nickel-plating stack 2 constituted of nickel layers 20 is manufactured. A rate of forming nickel layer 20 is changed depending on an amount of the sulfur additive included in nickel plating solution 200. Moreover, when a relative flow velocity of nickel plating solution 200 with respect to plating-target member 1 on which nickel layer 20 is to be formed is changed, a frequency of contact between a surface of plating-target member 1 and nickel ions in nickel plating solution 200 is changed. As a result, the rate of forming a nickel film on the surface of plating-target member 1 is increased. Since the rate of forming nickel layer 20 is changed in this way, the phosphorus concentrations in nickel layers 20 are changed. For example, when the amount of the sulfur additive included in nickel plating solution 200 is smaller, the phosphorus concentration in nickel layer 20 to be formed is increased. When the relative flow velocity of nickel plating solution 200 with respect to the surface of plating-target member 1 is faster, the phosphorus concentration in nickel layer 20 to be formed is decreased.

Manufacturing apparatus 100 shown in FIG. 2 forms the plurality of nickel layers 20 having different phosphorus concentrations by changing amounts of nickel (Ni) and phosphorus (P) to come into contact with plating-target member 1 per unit time. That is, nickel-plating stack 2 having a phosphorus concentration gradient is manufactured.

In order to manufacture nickel-plating stack 2 according to the first embodiment, at least one of convection mechanism 102 and shaking mechanism 103 is used.

Convection mechanism 102 causes convection of nickel plating solution 200. Nickel plating solution 200 may be circulated using convection mechanism 102 as shown in FIG. 2. As a result, the convection of nickel plating solution 200 may be caused in container 101.

Specifically, as shown in FIG. 2, convection mechanism 102 has a tubular path 102a and a pump 102b. Both ends of tubular path 102a are connected to container 101. Nickel plating solution 200 flows from container 101 into tubular path 102a via one end of tubular path 102a as indicated by an arrow, and passes through the inside of tubular path 102a. Pump 102b is provided in tubular path 102a. That is, pump 102b is provided between one end and the other end of tubular path 102a. Pump 102b sends out nickel plating solution 200. Nickel plating solution 200 having passed through tubular path 102a flows into container 101 again via the other end of tubular path 102a.

In this way, nickel plating solution 200 in container 101 is circulated through tubular path 102a. That is, the flow rate of nickel plating solution 200 to come into contact with plating-target member 1 (amount of nickel plating solution 200 to come into contact with plating-target member 1 per unit time) may be adjusted by circulating nickel plating solution 200 using convection mechanism 102.

The flow rate of nickel plating solution 200 to come into contact with plating-target member 1 is determined by a circulation flow rate of nickel plating solution 200 flowing into and out of container 101. The circulation flow rate may be 30 L/minute or more and 60 L/minute or less, or may be 40 L/minute or more and 50 L/minute or less.

When the circulation flow rate is increased, the number of times of making contact between plating-target member 1 and nickel ions in nickel plating solution 200 per unit time is increased. That is, when the flow rate of nickel plating solution 200 to come into contact with the surface of plating-target member 1 is increased, nickel layer 20 having a low phosphorus concentration is formed.

When nickel layer 20 having a low phosphorus concentration is formed, the amount of the sulfur additive in nickel plating solution 200 becomes small. Therefore, nickel plating solution 200 is adjusted to form nickel layer 20 having a high phosphorus concentration. As a result, nickel layer 20 having a high phosphorus concentration is formed adjacent to nickel layer 20 having a low phosphorus concentration.

Thus, nickel layer 20 having a desired phosphorus concentration can be formed by adjusting the flow rate of nickel plating solution 200 to come into contact with plating-target member 1.

Plating-target member 1 is accommodated in container 101 as described above. Plating-target member 1 is immersed in contact with nickel plating solution 200. Plating-target member 1 may be held by shaking mechanism 103. Shaking mechanism 103 shakes, for example, in an upward/downward direction. As a result, plating-target member 1 is shaken in the upward/downward direction. Shaking mechanism 103 may shake in a leftward/rightward direction, for example. In this way, the flow rate of nickel plating solution 200 to come into contact with plating-target member 1 may be adjusted by shaking plating-target member 1.

When nickel layer 20 is formed, hydrogen gas is generated at the surface of plating-target member 1. When the formation of nickel layer 20 proceeds with the hydrogen gas remaining at the surface of plating-target member 1, a defect called a pit or pinhole is generated. In order to prevent the generation of the defect, shaking mechanism 103 may include a shocking mechanism 104. Shocking mechanism 104 may be, for example, an air cylinder or an oscillation cam. As shown in FIG. 2, shocking mechanism 104 may be disposed on an inner wall surface of container 101.

Shocking mechanism 104 applies a shock to plating-target member 1. In this way, the hydrogen gas generated at the surface of plating-target member 1 can be removed from the surface of plating-target member 1. Moreover, with shocking mechanism 104, the effect of the convection of nickel plating solution 200 is increased.

A period of shaking by shaking mechanism 103 may be, for example, 1 second or more and 5 seconds or less. A period of applying the shock to plating-target member 1 by shocking mechanism 104 may be the same as the period of shaking by shaking mechanism 103.

Thus, by using shaking mechanism 103 to adjust the flow rate of nickel plating solution 200 to come into contact with plating-target member 1, nickel layer 20 having a desired phosphorus concentration can be formed.

In order to adjust the flow rate of nickel plating solution 200 to come into contact with plating-target member 1, convection mechanism 102 may be used, shaking mechanism 103 may be used, or both convection mechanism 102 and shaking mechanism 103 may be used.

<Modification of Manufacturing Apparatus for Nickel-Plating Stack>

FIG. 3 is a schematic diagram of a modification of manufacturing apparatus 100 for nickel-plating stack 2 according to the first embodiment. FIG. 3 corresponds to FIG. 2. Manufacturing apparatus 100 shown in FIG. 3 basically has the same configuration as that of manufacturing apparatus 100 shown in FIG. 2 and can attain the same effect, but is different therefrom in that nickel plating solution 200 is stirred.

Specifically, as shown in FIG. 3, convection mechanism 102 has a fan 102c. When fan 102c is rotated, nickel plating solution 200 in container 101 is stirred. Convection mechanism 102 may have a stirrer instead of fan 102c.

In this way, nickel plating solution 200 in container 101 may be stirred using convection mechanism 102 having fan 102c. By stirring nickel plating solution 200, the flow rate of nickel plating solution 200 to come into contact with plating-target member 1 may be adjusted.

The flow rate of nickel plating solution 200 to come into contact with plating-target member 1 is determined by the rotation speed of convection mechanism 102 that stirs nickel plating solution 200. The rotation speed of convection mechanism 102 may be 400 rpm or more and 1000 rpm or less, or may be 600 rpm or more and 800 rpm or less.

When the rotation speed of convection mechanism 102 is increased, the number of times of making contact between plating-target member 1 and nickel ions in nickel plating solution 200 is increased. That is, nickel layer 20 having a low phosphorus concentration is formed by increasing the flow rate of nickel plating solution 200 to come into contact with the surface of plating-target member 1.

Thus, nickel layer 20 having a desired phosphorus concentration can be formed by adjusting the flow rate of nickel plating solution 200 to come into contact with plating-target member 1 using convection mechanism 102 that stirs nickel plating solution 200.

<Method of Manufacturing Nickel-Plating Stack>

Next, a method of manufacturing nickel-plating stack 2 according to the first embodiment will be described. FIG. 4 is a flowchart of the method of manufacturing nickel-plating stack 2 according to the first embodiment. In the method of manufacturing nickel-plating stack 2 according to the first embodiment, first, a step (S1) of preparing nickel plating solution 200 including phosphorus and the sulfur additive, and plating-target member 1 is performed.

As shown in FIG. 2 or 3, nickel plating solution 200 is accommodated in container 101. Nickel plating solution 200 is, for example, an electroless nickel plating solution and includes phosphorus (P) and the sulfur additive.

Next, a step (S2) of forming nickel-plating stack 2 on plating-target member 1 using nickel plating solution 200 is performed. In this step (S2), nickel-plating stack 2 is formed using manufacturing apparatus 100 shown in FIG. 2 or 3. Specifically, plating-target member 1 is accommodated in container 101. Plating-target member 1 is immersed in nickel plating solution 200 for a certain period of time. In this way, a plating process is performed onto plating-target member 1.

When performing the plating process, the flow rate of nickel plating solution 200 to come into contact with plating-target member 1 is adjusted by using at least one or both of convection mechanism 102 and shaking mechanism 103 as shown in FIGS. 2 and 3.

In this way, nickel-plating stack 2 including nickel layers 20 having different phosphorus concentrations as shown in FIG. 1 is manufactured.

Once a state of nickel plating solution 200, such as its composition, is changed, it is difficult to return the state to the previous state. That is, it takes time to return the state of nickel plating solution 200 to the previous state. Therefore, when a method of changing the state of nickel plating solution 200 is used, mass productivity of nickel-plating stack 2 is low.

On the other hand, with the method of manufacturing nickel-plating stack 2 according to the first embodiment, the plurality of nickel layers 20 having different phosphorus concentrations can be formed without changing the state (for example, the phosphorus concentration in nickel plating solution 200 and the temperature of nickel plating solution 200) of nickel plating solution 200. That is, since the state of nickel plating solution 200 is not changed, the plurality of nickel layers 20 having different phosphorus concentrations can be formed with high productivity. As a result, mass productivity of nickel-plating stack 2 according to the first embodiment is improved.

In the case where a plurality of nickel plating solutions 200 are used, when plating-target member 1 is removed from a nickel plating solution 200, the surface of nickel layer 20 having been formed may be exposed to air, with the result that an oxide film may be formed.

On the other hand, according to the above-described method of manufacturing nickel-plating stack 2, the plurality of nickel plating solutions 200 having different phosphorus concentrations are not used to form nickel layers 20 having different phosphorus concentrations. That is, since the plurality of nickel layers 20 having different phosphorus concentrations are formed using one nickel plating solution 200, it is not necessary to remove plating-target member 1 from a nickel plating solution 200 during the step of forming nickel layers 20. Therefore, no oxide film is formed between nickel layers 20.

<Functions and Effects>

The method of manufacturing nickel-plating stack 2 according to the present disclosure includes: the step (S1) of preparing nickel (Ni) plating solution 200 including phosphorus (P) and the sulfur additive, and plating-target member 1; and the step (S2) of forming nickel-plating stack 2 on plating-target member 1 using nickel plating solution 200. Nickel-plating stack 2 includes nickel layers 20 having different phosphorus concentrations. In the method of manufacturing nickel-plating stack 2, nickel-plating stack 2 may include three or more nickel layers 20. Among the three or more nickel layers 20, the phosphorus concentrations are different between nickel layers 20 adjacent to each other. In the step (S2) of forming nickel-plating stack 2, the plurality of (three or more) nickel layers 20 may be formed using the same nickel plating solution 200. In the step (S2) of forming nickel-plating stack 2, the phosphorus concentration in nickel layer 20 may be changed by changing a state of contact (for example, a relative flow velocity of nickel plating solution 200 to come in contact with the surface of plating-target material 1, a flow direction of nickel plating solution 200 with respect to the surface of plating-target material 1, or the like) of nickel plating solution 200 with plating-target member 1.

In this way, the plurality of nickel layers 20 having different phosphorus concentrations can be formed without changing the state (the phosphorus concentration in nickel plating solution 200 and the temperature of nickel plating solution 200) of nickel plating solution 200. That is, since the state of nickel plating solution 200 is not changed, the plurality of nickel layers 20 having different phosphorus concentrations can be formed continuously. As a result, mass productivity of nickel-plating stack 2 according to the first embodiment is improved. Moreover, since the plurality of nickel layers 20 having different phosphorus concentrations are formed using one nickel plating solution 200, no oxide film is formed between nickel layers 20. By forming nickel layers 20 having different phosphorus concentrations in this way, nickel-plating stack 2 corresponding to a purpose of use can be obtained.

According to the method of manufacturing nickel-plating stack 2, in the step (S2) of forming nickel-plating stack 2, the convection of nickel plating solution 200 is caused.

In this way, the flow rate of nickel plating solution 200 to come into contact with plating-target member 1 is adjusted. That is, the phosphorus concentration in nickel layer 20 can be changed by changing the flow rate of nickel plating solution 200 without changing the state of nickel plating solution 200. Therefore, the plurality of nickel layers 20 having different phosphorus concentrations can be readily formed.

According to the method of manufacturing nickel-plating stack 2, in the step (S2) of forming nickel-plating stack 2, plating-target member 1 is shaken.

In this way, the flow rate of nickel plating solution 200 to come into contact with plating-target member 1 is adjusted. That is, the phosphorus concentration in nickel layer 20 can be changed by changing the flow rate of nickel plating solution 200 without changing the state of nickel plating solution 200. Therefore, the plurality of nickel layers 20 having different phosphorus concentrations can be readily formed.

Manufacturing apparatus 100 for nickel-plating stack 2 according to the present disclosure includes container 101 and at least one of convection mechanism 102 and shaking mechanism 103. Container 101 accommodates nickel plating solution 200. Convection mechanism 102 causes the convection of nickel plating solution 200. Shaking mechanism 103 shakes plating-target member 1.

In this way, the plurality of nickel layers 20 having different phosphorus concentrations can be formed without changing the state (the phosphorus concentration in nickel plating solution 200 and the temperature of nickel plating solution 200) of nickel plating solution 200. That is, since the state of nickel plating solution 200 is not changed, the plurality of nickel layers 20 having different phosphorus concentrations can be formed continuously. As a result, mass productivity of nickel-plating stack 2 according to the first embodiment is improved. Moreover, since the plurality of nickel layers 20 having different phosphorus concentrations are formed using one nickel plating solution 200, no oxide film is formed between nickel layers 20. By forming nickel layers 20 having different phosphorus concentrations in this way, nickel-plating stack 2 corresponding to a purpose of use can be obtained.

Nickel-plating stack 2 according to the present disclosure includes at least three or more nickel layers 20. Two nickel layers 20 having different phosphorus concentrations are disposed in direct contact with each other.

By forming nickel layers 20 having different phosphorus concentrations in this way, nickel-plating stack 2 corresponding to a purpose of use can be obtained.

Second Embodiment

<Configuration of Semiconductor Device>

FIG. 5 is a schematic cross sectional view of a semiconductor device 10 according to a second embodiment. FIG. 5 corresponds to FIG. 1. Semiconductor device 10 shown in FIG. 5 is a semiconductor device including nickel-plating stack 2 according to the first embodiment and shown in FIG. 1. Specifically, semiconductor device 10 includes plating-target member 1, nickel-plating stack 2 according to the first embodiment, and a back metal 3. Plating-target member 1 includes a semiconductor base member 11 and a wiring layer 12.

The material of semiconductor base member 11 may be, for example, silicon. Wiring layer 12 is formed on semiconductor base member 11. The material of wiring layer 12 may include aluminum (Al) and silicon (Si). Nickel-plating stack 2 is disposed on wiring layer 12. Back metal 3 is formed in a region opposite to a region in which wiring layer 12 is disposed when viewed from semiconductor base member 11. The material of back metal 3 is, for example, a metal such as aluminum. It should be noted that a semiconductor element (not shown) is formed on semiconductor base member 11.

Thus, nickel-plating stack 2 may be used as a member included in semiconductor device 10.

A method of manufacturing semiconductor device 10 according to the second embodiment uses the method of manufacturing nickel-plating stack 2 according to the first embodiment. In the method of manufacturing semiconductor device 10, first, the same step as the step (S1) of preparing nickel plating solution 200 and plating-target member 1 as shown in FIG. 4 is performed. In this step (S1), plating-target member 1 includes semiconductor base member 11 and wiring layer 12.

Next, the same step as the step (S2) of forming nickel-plating stack 2 as shown in FIG. 4 is performed. In this step (S2), nickel-plating stack 2 is formed on wiring layer 12. After nickel-plating stack 2 is formed, back metal 3 may be formed by any method. Back metal 3 is formed in a region opposite to a region in which nickel-plating stack 2 is disposed when viewed from plating-target member 1. Thus, semiconductor device 10 as shown in FIG. 5 can be obtained.

<Functions and Effects>

The method of manufacturing semiconductor device 10 according to the present disclosure uses the method of manufacturing nickel-plating stack 2. Plating-target member 1 includes semiconductor base member 11.

Thus, nickel-plating stack 2 may be used as a member included in semiconductor device 10.

Third Embodiment

<Configuration of Nickel Plating Layer>

FIG. 6 is a schematic cross sectional view of a nickel-plating stack 2 according to a third embodiment. FIG. 6 corresponds to FIG. 1. Nickel-plating stack 2 shown in FIG. 6 basically has the same configuration as that of nickel-plating stack 2 shown in FIG. 1 and can attain the same effect, but is different therefrom in that plating-target member 1 includes an underlying layer 15.

Specifically, plating-target member 1 includes a base member 14 and underlying layer 15. The material of base member 14 is, for example, copper (Cu). Base member 14 has a high electrical conductivity. Underlying layer 15 is formed on base member 14. The material of underlying layer 15 is copper. Underlying layer 15 may be formed by an electroless plating method.

Nickel-plating stack 2 is disposed on underlying layer 15. Nickel-plating stack 2 may be a nickel-plating stack 2 in which medium and high phosphorus layers are sequentially stacked. The thickness of nickel-plating stack 2 is, for example, 0.3 μm or more and 10.0 μm or less.

As shown in Table 1, the crystal states of the medium phosphorus layer and the high phosphorus layer are different. The medium phosphorus layer is a crystal with a magnetic property. The high phosphorus layer is amorphous with no magnetic property. When an electromagnetic wave enters nickel-plating stack 2, the electromagnetic wave comes thereinto across nickel layers 20, which are the plurality of medium phosphorus layers. As a result, a high shielding effectiveness can be attained in nickel-plating stack 2.

FIG. 7 is a schematic diagram illustrating the shielding effectiveness. A part of an electromagnetic wave (incoming wave 41) having entered a shielding member 4 is reflected by shielding member 4 as a reflected wave 42. A part of the electromagnetic wave (incoming wave 41) having entered shielding member 4 travels in shielding member 4 as an attenuated wave 43. A part of the electromagnetic wave (incoming wave 41) having entered shielding member 4 is multiply-reflected in shielding member 4 as a multiply-reflected wave 44. A part of the electromagnetic wave (incoming wave 41) having entered shielding member 4 passes through shielding member 4 as a transmitted wave 45.

The shielding effectiveness of shielding member 4 is represented by an amount of reduction of the energy of the electromagnetic wave when incoming wave 41 passes through shielding member 4 as transmitted wave 45. The amount of reduction is a sum of a reflection loss representing the loss as reflected wave 42, an absorption loss representing the loss as attenuated wave 43 due to absorption by shielding member 4, and a multiple reflection correction representing the loss as multiply-reflected wave 44 due to multiple reflection in shielding member 4. It should be noted that the unit of each of the amount of reduction, the reflection loss, the absorption loss, and the multiple reflection correction is decibel (dB). A product having an excellent shielding effectiveness is referred to as an electromagnetic wave shield.

Thus, nickel-plating stack 2 can be used as shielding member 4. The copper used as base member 14 is readily oxidized in an atmospheric air. Therefore, the shielding effectiveness of base member 14 may be reduced.

To address this, an electroless nickel plating layer or a permalloy plating layer is formed on the copper having high electrical conductivity, thereby preventing the oxidation of the copper.

Since the phosphorus concentrations in the plurality of nickel layers 20 are different, the electrical conductivities of the nickel layers are different. Therefore, by forming nickel-plating stack 2 in which the medium and high phosphorus layers are stacked sequentially on base member 14, the absorption loss representing the loss as attenuated wave 43 due to absorption by shielding member 4 shown in FIG. 7 is increased. As a result, the amount of reduction indicating the shielding effectiveness is increased, thus resulting in improved shielding effectiveness. Moreover, the wear resistance of nickel-plating stack 2 is improved.

In a method of manufacturing nickel-plating stack 2 according to the third embodiment, first, the same step as the step (S1) of preparing nickel plating solution 200 and plating-target member 1 as shown in FIG. 4 is performed. In this step (S1), plating-target member 1 includes base member 14 and underlying layer 15. Underlying layer 15 may be formed by the electroless plating method.

Next, the same step as the step (S2) of forming nickel-plating stack 2 as shown in FIG. 4 is performed. In this step (S2), nickel-plating stack 2 is formed on underlying layer 15. Thus, semiconductor device 10 as shown in FIG. 6 can be obtained.

<Functions and Effects>

According to the method of manufacturing nickel-plating stack 2, plating-target member 1 includes underlying layer 15.

In this way, by forming nickel-plating stack 2 in which the medium and high phosphorus layers are stacked sequentially on underlying layer 15, a product having an improved shielding effectiveness can be obtained.

Fourth Embodiment

<Configuration of Nickel Plating Layer>

FIG. 8 is a schematic partial enlarged cross sectional view of a nickel-plating stack 2 according to a fourth embodiment. Nickel-plating stack 2 shown in FIG. 8 basically has the same configuration as that of nickel-plating stack 2 shown in FIG. 1 and can attain the same effect, but is different therefrom in that a plurality of recesses 2a are provided in a portion of nickel-plating stack 2.

Specifically, as shown in FIG. 8, a connection member 5 is in contact with an outer peripheral surface 2s of nickel-plating stack 2. Connection member 5 is a member that can be connected to outer peripheral surface 2s of nickel-plating stack 2. Connection member 5 is disposed on plating-target member 1. FIG. 8 shows a portion of a semiconductor device including plating-target member 1, nickel-plating stack 2, and connection member 5, for example.

The material of connection member 5 is a material that can be readily molded. The material of connection member 5 may be a resin material such as polyimide, may be a metal material such as a solder, or may be glass or the like, for example.

Outer peripheral surface 2s is provided with the plurality of recesses 2a. The plurality of recesses 2a are filled with portions of the connection member. Since recesses 2a are thus filled with connection member 5, a contact area between nickel-plating stack 2 and connection member 5 is increased. As a result, adhesion between nickel-plating stack 2 and connection member 5 is improved. Further, affinity between nickel-plating stack 2 and connection member 5 is improved.

<Method of Manufacturing Nickel-Plating Stack>

Next, a method of manufacturing nickel-plating stack 2 according to the fourth embodiment will be described. FIG. 9 is a flowchart of the method of manufacturing nickel-plating stack 2 according to the fourth embodiment. In the method of manufacturing nickel-plating stack 2 according to the fourth embodiment, the same steps as the step (S1) of preparing nickel plating solution 200 and plating-target member 1 and the step (S2) of forming nickel-plating stack 2 as shown in FIG. 4 are sequentially performed.

Next, a step (S3) of forming the plurality of recesses 2a in nickel-plating stack 2 using an electrolytic solution including a metal ion more noble than nickel (Ni) is performed. In this step (S3), the plurality of recesses 2a are formed in nickel-plating stack 2 using the electrolytic solution. The electrolytic solution includes the metal ion more noble than nickel (Ni). Examples of the metal more noble than nickel include tin (Sn), lead (Pb), copper (Cu), silver (Ag), gold (Au), and the like.

When the electrolytic solution comes into contact with nickel-plating stack 2, a potential difference is caused at outer peripheral surface 2s of nickel-plating stack 2. That is, nickel layers 20 each having a relatively low phosphorus concentration in nickel-plating stack 2 are locally corroded. Among nickel layers 20 exposed on outer peripheral surface 2s (side surface located at the outer peripheral end) of nickel-plating stack 2, nickel layers 20 each having a low phosphorus concentration are corroded, thereby forming the plurality of recesses 2a in outer peripheral surface 2s. Thereafter, connection member 5 is formed. As a method of manufacturing connection member 5, any conventionally known method can be used. In this way, the device shown in FIG. 8 is obtained.

Since the plurality of recesses 2a are thus formed in outer peripheral surface 2s of nickel-plating stack 2 that is in contact with connection member 5, the adhesion between nickel-plating stack 2 and connection member 5 is improved. Further, the affinity between nickel-plating stack 2 and connection member 5 is improved.

<Functions and Effects>

The method of manufacturing nickel-plating stack 2 includes, after the step (S2) of forming nickel-plating stack 2, the step (S3) of forming the plurality of recesses 2a in nickel-plating stack 2 using the electrolytic solution including the metal ion more noble than nickel (Ni).

In this way, the plurality of recesses 2a are formed in outer peripheral surface 2s of nickel-plating stack 2. As a result, since recesses 2a are filled with connection member 5, the contact area between nickel-plating stack 2 and connection member 5 is increased. That is, the adhesion between nickel-plating stack 2 and connection member 5 is improved. Further, the affinity between nickel-plating stack 2 and connection member 5 is improved.

Although the embodiments of the present disclosure have been described, the embodiments disclosed herein are illustrative and non-restrictive in any respect. The scope of the present disclosure is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.