KR100637870B1 - Metal substrate for semiconductor device and plating solution and plating method for the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal substrate for a semiconductor device, a plating solution and a plating method therefor, and a technical problem to be solved is to improve the hardness, corrosion resistance, and wear resistance of a metal substrate using a nickel-phosphorus plating layer.

To this end, the gist of the solution according to the present invention discloses a metal substrate for a semiconductor device including a metal substrate and a main plating layer formed of nickel-phosphorus alloy to have a thickness of 0.2 to 2.0 μm on the surface of the metal substrate.

In addition, any one selected from nickel sulfamate or nickel sulfate is used as a source of nickel, and the concentration weight ratio (wt%) of nickel and phosphorus is 1: 0.5 to 1.2, and the vacancy of phosphorus is phosphoric acid and phosphorous acid. The ratio of is 1: 0.15 ~ 0.80, the total concentration of the nickel, phosphate and phosphorous acid is 100 ~ 250g / l, ethylene oxide is used as an additive, the plating solution is started with a ratio of 1: 0.002 ~ 0.005 .

In addition, a plating method is disclosed in which a metal substrate is plated using the above-described plating liquid, but the temperature of the plating liquid is 50 to 80 ° C., and the acidity (pH) is 0.5 to 3.

Semiconductor, Metal Substrate, Leadframe, Plating, Nickel-In

Description

Metal substrate for semiconductor device and plating solution and plating method therefor {Metal substrate for semiconductor device and plating solution and plating method for the same}

FIG. 1A is a plan view showing an example of a metal substrate for a general semiconductor device, and FIG. 1B is a sectional view thereof.

2 is a cross-sectional view showing a plating state of a metal substrate for a general semiconductor device.

3 is a cross-sectional view illustrating a metal substrate for a semiconductor device according to an embodiment of the present invention.

4 is a cross-sectional view illustrating a metal substrate for a semiconductor device according to another embodiment of the present invention.

FIG. 5A illustrates SEM (Scanning Electron Microscope) images and EDS (Energy Dispersive Spectroscopy) analysis results of a uniform plating layer, and FIG. 5B illustrates SEM images and EDS analysis results of a defective plating layer having curved surfaces.

<Description of Symbols for Main Parts of Drawings>

100,101; Metal substrate according to the present invention

31; Metal substrate

32; Sub-plating layer

33; Main plating layer

The present invention relates to a metal substrate for a semiconductor device and a plating solution and plating method therefor, and more particularly, to a metal substrate for a semiconductor device and a plating solution and plating method therefor that can improve hardness, corrosion resistance and wear resistance.

Generally, a metal substrate for a semiconductor device (for example, a lead frame) is a core material of a semiconductor device together with a semiconductor chip, and serves as a conductor for connecting the inside and the outside of the semiconductor device and the support for supporting the semiconductor chip. Play a role.

Metal substrates having the above functions are usually manufactured using mechanical methods and chemical methods. The mechanical method is to mold a thin metal substrate into a desired shape by using a press mold apparatus which is sequentially transferred. This method is a manufacturing method mainly applied to mass production of a metal substrate, whereas a chemical method A chemical etching method that uses chemicals to corrode topical portions of metal substrates to form the desired product. This method is a manufacturing method that is applied mainly for production of small quantities and small quantities.

Regardless of the two manufacturing methods described above, the manufactured metal substrate may have various structures depending on the form of the metal substrate, for example, the structure of the discrete metal substrate common to FIGS. 1A and 1B. Is shown.

As shown, the metal substrate 1 includes a frame 2 for supporting various structures during the semiconductor manufacturing process, a die pad 3 for mounting a semiconductor chip as a memory device connected to the frame 2, and a wire; It consists of a plurality of leads 4 connected to the semiconductor chip by bonding.

In addition, as shown in FIG. 2, the plating structure of the conventional metal substrate 1 generally has a predetermined thickness formed on the surface of the metal substrate 21 (frame, die pad, lead, etc.) and the metal substrate 21. The nickel plating layer 22 is comprised.

On the other hand, in the nickel plating method that is commonly used in the prior art, nickel sulfate or nickel sulfamate, the main source of nickel ions, nickel bromide or nickel chloride to help dissolution of the positive electrode and increase the conductivity of the electrolyte, and the acidity (pH) in the solution It is composed of boric acid, etc., which helps to produce evenly ductile and soft particles as a buffer, and the water used to dissolve them is basically free from impurities and contains a small amount of additives such as polishes or wetting agents to have nickel electrodeposition characteristics. To form a plating liquid.

However, the conventional method has a problem in that the metal substrate exposed to the external environment has a corrosion resistance and abrasion resistance decrease of the plating layer due to a chemical reaction when used for a long time, thereby deteriorating the function and reliability of the semiconductor chip.

The present invention is to overcome the above-mentioned conventional problems, an object of the present invention to provide a metal substrate for a semiconductor device that can improve the hardness, corrosion resistance and abrasion resistance using a nickel-phosphorus plating layer, and a plating solution and plating method therefor. It is.

In order to achieve the above object, the present invention discloses a metal substrate for a semiconductor device comprising a metal substrate and a main plating layer formed of a nickel-phosphorus alloy to have a thickness of 0.2 to 2.0 μm on the surface of the metal substrate.

Here, the metal substrate may be any one selected from copper, copper alloy or nickel-iron alloy.

In addition, a sub plating layer formed of nickel may be further formed between the metal substrate and the main plating layer to have a thickness of 0.5 to 4.0 μm.

In addition, the phosphorus content of the main plating layer may be 3.5 ~ 15wt%.

Furthermore, in order to achieve the above object, the present invention discloses a plating solution for a metal substrate for a semiconductor device in which nickel and phosphorus are present together.

Here, the nickel is a source selected from any one of nickel sulfamate or nickel sulfate, and the phosphorus may be vacancies of phosphorous acid and phosphorous acid.

In addition, the concentration weight ratio (wt%) of the nickel and phosphorus is 1: 0.5 to 1.2, the ratio of the phosphorous acid and phosphorous acid is 1: 0.15 to 0.80, the total concentration of the nickel, phosphorous acid and phosphorous acid is 150 ~ 220g / ℓ Can be.

In addition, ethylene oxide is added to the plating solution, and the ratio of phosphorus and ethylene oxide may be 1: 0.002 to 0.005.

Furthermore, in order to achieve the above object, the present invention is to plate the metal substrate using the above-described plating solution, the temperature of the plating solution is 50 ~ 80 ℃, the acidity (pH) for the semiconductor device for A plating method for a metal substrate is disclosed.

Here, the metal substrate may be any one selected from copper, copper alloy or nickel-iron alloy.

In addition, nickel may be plated in advance on the metal substrate.

As described above, the present invention maintains the desired phosphorus content according to the change of the concentration of phosphorous and phosphorous acid on the metal substrate and the use of ethylene oxide, thereby providing excellent wear resistance and excellent product quality. Will be provided.

In addition, the nickel-phosphorus plating layer according to the present invention compensates for the lack of hardness and abrasion resistance lacking in the nickel plating layer, and changes the surface having a large porosity, which is a defect of the plating layer of the metal substrate, into an amorphous structure by the vacant phosphorus. Corrosion resistance is improved. Therefore, due to these characteristics, the thickness of the plating layer can be reduced, and manufacturing cost can be reduced due to the downward management of the thickness of the plating layer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that those skilled in the art may easily implement the present invention.

3 is a cross-sectional view illustrating a metal substrate 100 for a semiconductor device according to an embodiment of the present invention.

As shown, the metal substrate 100 for semiconductor devices according to the present invention includes a substantially plate-shaped metal substrate 31 and a main plating layer 33 formed of nickel-phosphorus alloy on the surface of the metal substrate 31. .

First, the metal substrate 31 may be any one selected from copper, a copper alloy, a nickel-iron alloy, or an equivalent thereof, but the material is not limited thereto.

In addition, the main plating layer 33 may be formed only on one surface of the metal substrate 31 or on both surfaces, and the thickness is 0.2 to 2.0 μm and is mainly formed of a nickel-phosphorus alloy.

Here, the main plating layer 33 formed of the nickel-phosphorus alloy is preferably adjusted to have a phosphorus content of 3.5 ~ 15wt%. The reason for limiting the phosphorus content to such a value is that the coarse crystal phase of the nickel is changed to an amorphous phase in which the coarse crystal phase becomes very fine or disappears due to the vacancy between nickel and phosphorus at the above content. That is, the amorphous phase structure has excellent corrosion resistance and abrasion resistance as already known, and therefore, when the phosphorous content is as described above, the corrosion resistance and wear resistance of the metal substrate are greatest. For example, when the main plating layer 33 having a phosphorus content of 3.5 wt% or less cannot be made finer in the nickel plating layer, corrosion resistance and wear resistance are lowered. In addition, when the main plating layer 33 having a phosphorus content of 15 wt% or more is formed, surface cracks are formed due to internal stress during surface vacancy of phosphorus.

4 is a cross-sectional view illustrating a metal substrate 101 for a semiconductor device according to another embodiment of the present invention.

As shown in the present invention, the sub plating layer 32 may be further formed of nickel to have a thickness of 0.5 μm to 4.0 μm between the metal substrate 31 and the main plating layer 33. However, the material of the sub plating layer 32 is not limited in the present invention. That is, in addition to nickel, copper or equivalents thereof may be used as the sub plating layer 32.

Next, the composition of the plating liquid for the metal substrate for semiconductor devices by this invention is demonstrated.

The plating liquid according to the present invention largely consists of nickel and phosphorus.

The nickel may be any one selected from nickel sulfamate, nickel sulfate, or equivalents thereof as a source, but the material is not limited thereto.

In addition, the phosphorus may be vacancy (eu, eutectoid) of phosphate and phosphorous acid.

In addition, the concentration weight ratio (wt%) of the nickel and phosphorus may be 1: 0.5 to 1.2, and the ratio of the phosphorous acid and the phosphorous acid may be 1: 0.15 to 0.80. In addition, the total concentration of the nickel, phosphate and phosphorous acid may be 150 ~ 220g / ℓ. In addition, ethylene oxide may be used as an additive, and the ratio of phosphorus and ethylene oxide may be 1: 0.002 to 0.006.

Here, when the weight ratio (wt%) of nickel and phosphorus is less than 1: 0.5, the concentration of ions is low, so that it is difficult to obtain the phosphorus content in the plating layer more than 3.5%, and in 1: 1.2 or more, the voltage is increased due to the excessive concentration of phosphorus so that the adhesion of the plating layer is increased. It is easy to fall.

In addition, when the ratio of the phosphorous acid and the phosphorous acid is 1: 0.15 or less, it is difficult to obtain the phosphorus concentration of 3.5% or more, and when the ratio of 1: 0.80 or more is difficult to secure the uniformity of the plating layer.

In addition, when the total concentration of nickel, phosphate, and phosphorous acid is 150 g / l or less, less ions are generated in the plating solution, so that a ballistic plating is generated, and thus adhesion is reduced. In addition, when the total concentration of nickel, phosphate and phosphorous acid is 220 g / l or more, the plating particles become large due to collision of ions and generation of complex ions, resulting in poor wear resistance.

On the other hand, when the concentration ratio of phosphorus and ethylene oxide is less than 1: 0.002, the particles of the plating layer are not made fine and wear resistance is reduced, and when the ratio is greater than 1: 0.006, the adhesion of the plating layer is reduced.

Next, the plating method according to the present invention will be described.

The present invention is to plate the metal substrate using a plating solution having a composition ratio as described above, the temperature of the plating solution is 50 ~ 80 ℃, acidity (pH) is to be 0.5 to 3.

Here, when the temperature of the plating liquid is about 50 ° C. or less, it is difficult to secure the phosphorus content (3.5 to 15 wt%) as described above in the plating layer, and when the temperature is about 80 ° C. or more, uniform electrodeposition of the plating layer is difficult. In addition, at pH 1 or less, adhesion of the plating layer is poor due to hydrogen generation, and at pH 3 or higher, it is difficult to secure a phosphorus content (3.5 to 15 wt%).

In addition, the present invention may be any one selected from copper, a copper alloy, a nickel-iron alloy, or an equivalent thereof as described above as the metal substrate, but the present invention is not limited thereto.

In addition, nickel or an equivalent thereof may be preplated on the metal substrate, but this is not limited in the present invention.

Example  And Comparative example

Hereinafter, examples and comparative examples according to the present invention will be described with reference to Tables 1 to 4, FIGS. 5A and 5B.

(1) sample preparation

First, a metal plating such as copper, a copper alloy, or a nickel-iron alloy is formed with a nickel plating solution to form a sub plating layer with a thickness of 0.5 to 4 µm, and the main plating layer is 0.2 to 2.0 µm with a nickel-phosphorus plating solution having a composition as described above. It formed in the thickness of. In addition, the wear resistance is a value according to the change in the heat treatment temperature. In addition, in the following description, the plating layer means the main plating layer described above.

(2) Comparison of wear resistance of plating layer according to phosphorus content

(3) Comparison of hardness of plating layer according to phosphorus content

As shown in Table 1 and Table 2 above, it can be seen that the metal substrate according to the present invention has excellent wear resistance and hardness regardless of the heat treatment temperature at a phosphorus content of 3.5 wt% or more.

(4) Plating Layer Characteristics According to Plating Solution Composition

Here, the adhesiveness of the plating layer was bent after roughly 180 degrees (OT bending), straightened, and then peeled off after adhesion with a tape. If the plating layer did not adhere to the tape, it was treated as good. In addition, wear resistance was good when it was 20 or more at the time of 200 degreeC heat processing, and it was set as bad when it was less. In addition, the plating surface was treated as bad if the surface was uniform as shown in FIG. 5A through SEM image analysis, and if the curvature was seen as shown in FIG. 5B.

As in Examples 1 to 3, the concentration ratio of nickel and phosphorus is 1: 0.7 to 1.1, the concentration ratio of phosphorous and phosphorous acid is 1: 0.5, the concentration ratio of nickel + phosphoric acid and phosphorous acid 180 (g / L), phosphorus and ethylene oxide is 1: 0.004. Plating surface, adhesion and wear resistance were all good.

However, as in Comparative Examples 4 and 5, the concentration ratio of nickel and phosphorus is 1: 0.4 or 1.3, the concentration ratio of phosphorous acid and phosphorous acid is 1: 0.5, the concentration ratio of nickel + phosphoric acid + phosphorous acid 180 (g / L), phosphorus and ethylene oxide 1: At 0.004, adhesion was good but plating surface and abrasion resistance were poor.

Next, as in Examples 6 to 8, the concentration ratio of nickel and phosphorus is 1: 0.8, the concentration ratio of phosphorous and phosphorous acid is 1: 0.3 to 0.7, the concentration ratio of nickel + phosphorous acid and phosphorous acid 180 (g / L), phosphorus and ethylene oxide is 1: 0.004. In one case, the plating surface, adhesion and wear resistance were all good.

However, as in Comparative Examples 9 and 10, the concentration ratio of nickel and phosphorus is 1: 0.8, the concentration ratio of phosphorous and phosphorous acid is 1: 0.1 or 0.9, the concentration ratio of nickel + phosphorous acid and phosphorous acid 180 (g / L), phosphorus and ethylene oxide is 1: 0.004. In this case, adhesion was good but plating surface and wear resistance were poor.

Subsequently, as in Examples 11 to 13, the concentration ratio of nickel and phosphorus is 1: 0.8, the concentration ratio of phosphorous and phosphorous acid is 1: 0.5, the concentration ratio of nickel + phosphoric acid and phosphorous acid 170 to 210 (g / L), phosphorus and ethylene oxide is 1: 0.004. In one case, the plating surface, adhesion and wear resistance were all good.

However, as in Comparative Examples 14 and 15, the concentration ratio of nickel and phosphorus is 1: 0.8, the concentration ratio of phosphorous acid and phosphorous acid is 1: 0.5, the concentration ratio of nickel + phosphorous acid and phosphorous acid 140 or 230 (g / L), phosphorus and ethylene oxide 1: 0.004. In this case, adhesion was good but plating surface and wear resistance were poor.

Subsequently, as in Examples 16 to 18, the concentration ratio of nickel and phosphorus is 1: 0.8, the concentration ratio of phosphorous and phosphorous acid is 1: 0.5, the concentration ratio of nickel + phosphorous acid and phosphorous acid 180 (g / L), phosphorus and ethylene oxide is 1: 0.003 to 0.005. In one case, the plating surface, adhesion and wear resistance were all good.

However, as in Comparative Examples 19 and 20, the concentration ratio of nickel and phosphorus is 1: 0.8, the concentration ratio of phosphorous acid and phosphorous acid is 1: 0.5, the concentration ratio of nickel + phosphorous acid + phosphorous acid 180 (g / L), phosphorus and ethylene oxide is 1: 0.001 or 0.007. In this case, the adhesion is good, but the plating surface and the wear resistance are both poor.

In conclusion, the plating solution according to the present invention has a concentration ratio of nickel to phosphorus (wt%) 1: 0.7 to 1.1, phosphorous and phosphorous acid 1: 0.3 to 0.7, nickel + phosphorous acid + phosphorous acid 170 to 210 g / L, phosphorus and ethylene oxide 1: 0.003 to When it is 0.005, it can be seen that the plating surface, adhesiveness and abrasion resistance are the best.

(5) Plating layer characteristics according to plating conditions

As in Examples 1 to 3, the plating surface, adhesiveness and wear resistance were all good when the plating solution had a temperature of 50 to 80 ° C., an acidity (pH) 2, and a current density of 10 A / dm ³ .

However, as in Comparative Examples 4 and 5, the plating surface, adhesion and abrasion resistance were almost poor at the temperature of the plating liquid of 40 or 90 ° C., the acidity (pH) 2 and the current density of 10 A / dm ³ .

Subsequently, when the temperature of the plating liquid, the acidity (pH) of 1 to 3, and the current density of 10 A / dm ³ were used as in Inventive Examples 6 to 8, the plating surface, adhesiveness, and wear resistance were all excellent.

However, as in Comparative Examples 9 and 10, when the temperature of the plating liquid was 65 ° C., the acidity (pH) 0.5 or 4, and the current density was 10 A / dm ³ , the adhesion was good but the plating surface and the wear resistance were poor.

Subsequently, in the case of the temperature of the plating liquid, the acidity (pH) 2, and the current density of 4 to 15 A / dm ³ as in Inventive Examples 11 to 13, the plating surface, adhesiveness and wear resistance were all good.

However, as in Comparative Examples 14 and 15, when the temperature of the plating liquid was 65 ° C., the acidity (pH) 2, the current density 2, or 18 A / dm ³ , the adhesion was good but the plating surface and the wear resistance were poor.

In conclusion, the plating method according to the present invention can be seen that the plating surface, adhesion and wear resistance is best when the temperature of the plating solution 50 ~ 80 ℃, pH (pH) 1 ~ 3, current density 4 ~ 15dm ³ .

As described above, the present invention maintains the desired phosphorus content according to the change in the concentration of phosphorous and phosphorous acid on the metal substrate and the use of additives ethylene oxide, excellent wear resistance, excellent new product quality metal substrate for semiconductor devices and plating solutions therefor and It provides a plating method.

In addition, the nickel-phosphorus plating layer according to the present invention compensates for the lack of hardness and abrasion resistance lacking in the nickel plating layer, and changes the surface having a large porosity, which is a defect of the plating layer of the metal substrate, into an amorphous structure by the vacant phosphorus. Corrosion resistance is improved. Therefore, due to these characteristics, the thickness of the plating layer can be reduced, and manufacturing cost can be reduced due to the downward management of the thickness of the plating layer.

What has been described above is only one embodiment for carrying out a metal substrate for a semiconductor device and a plating solution and plating method for the same according to the present invention, the present invention is not limited to the above-described embodiment, in the claims As claimed, any person having ordinary skill in the art without departing from the gist of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

Claims (11)

delete delete A metal substrate formed of any one selected from copper, a copper alloy or a nickel-iron alloy, It includes a main plating layer formed of a nickel-phosphorous alloy to have a thickness of 0.2 ~ 2.0㎛ on the surface of the metal substrate, The metal substrate for a semiconductor device, characterized in that the sub-plating layer formed of nickel is formed between the metal substrate and the main plating layer to have a thickness of 0.5 ~ 4.0㎛. 4. The metal substrate for semiconductor devices according to claim 3, wherein the phosphorus content of the main plating layer is 3.5 to 15 wt%. delete delete In the plating liquid for a metal substrate for semiconductor devices in which nickel and phosphorus are present together, The nickel is a source selected from either sulfamic acid nickel or nickel sulfate, the phosphorus is vacancies of phosphate and phosphorous acid, The concentration weight ratio (wt%) of nickel and phosphorus is 1: 0.5 to 1.2, The ratio of the phosphate and phosphorous acid is 1: 0.15 ~ 0.80, The total concentration of the nickel, phosphate and phosphorous acid is 150 ~ 220g / ℓ plating solution for a metal substrate for a semiconductor device. 8. The plating solution according to claim 7, wherein ethylene oxide is added to the plating solution, and the ratio of phosphorus and ethylene oxide is 1: 0.002 to 0.006. A plating method for a metal substrate for a semiconductor device, characterized in that the plating of the metal substrate using the plating solution of claim 8, wherein the temperature of the plating solution is 50 ~ 80 ℃, acidity (pH) is 1 ~ 3. 10. The plating method according to claim 9, wherein the metal substrate is any one selected from copper, copper alloy or nickel-iron alloy. The plating method for a metal substrate for a semiconductor device according to claim 9 or 10, wherein nickel is preplated on the metal substrate.

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