Reliability-improved bonding wire for semiconductor device

Abstract

The present invention relates to a bonding wire applied to an automotive semiconductor, and more specifically, may provide a bonding wire having improved reliability by means of the changing of the material of a plating layer formed on the outermost portion of the bonding wire so that, during a semiconductor packaging process, the formation of an interfacial bonding layer (IMC) formed at the adhesive interface of the Cu bonding wire and an aluminum pad is suppressed, and a bonding force is strengthened.

Description

Bonding wire for semiconductor devices with improved reliability

[0001] The present invention relates to a Cu-based bonding wire applied to an electric semiconductor device, and more specifically, to a bonding wire with improved reliability by suppressing the formation of an inter-metallic compound (IMC) formed at the bonding interface between the Cu bonding wire and an aluminum (Al) pad during the semiconductor packaging process and strengthening the bonding strength by changing the material of the plating layer formed on the outermost surface of the bonding wire.

[0002]

[0003] Currently, the use of semiconductors is increasing across various industrial sectors, leading to a gradual rise in demand for bonding wires, a material used in semiconductors. Bonding wire is a core material in the semiconductor packaging process, serving as a component that connects lead frames to silicon chips to transmit electrical signals.

[0004] Since these bonding wires require electrical and thermal properties such as high strength, high conductivity, and high heat resistance despite being fine wires, they are generally manufactured using metals such as Au, Ag, and Cu. Among these, Cu wires are increasing in demand across various fields because they offer the advantages of high electrical conductivity and tensile strength as well as a price that is only about 1 / 10,000th that of Au. However, compared to Au wires, Cu wires have the disadvantage of lower reliability due to their susceptibility to oxidation or corrosion. In particular, automotive semiconductors represent a growing demand for semiconductors; since these automotive semiconductors require high reliability for passenger safety, Au wires are primarily used instead of Cu wires. However, due to the increasing demand for automotive semiconductors and the rising price of Au, research is continuously being conducted to replace some areas of Au wires with Cu wires.

[0005] Meanwhile, when applying Cu-based bonding wires to semiconductors for automotive applications, the reliability of the wire is degraded due to S ions and Cl ions within the EMC (Epoxy Molding Compound) used to protect the semiconductor circuit from vibration and shock; consequently, the scope of their use is limited compared to Au. To compensate for these drawbacks of Cu bonding wires, conventional methods attempted to improve reliability by plating with palladium (Pd), which has high corrosion resistance. However, since Pd is difficult to process and shortens the lifespan of auxiliary materials, an additional Au plating process became essential. Consequently, increased process time and the input of additional plating auxiliary materials are required.

[0006]

[0007] The present invention has been devised to solve the aforementioned problems, and its technical objective is to provide a Cu-based bonding wire capable of increasing reliability during the semiconductor packaging process for electric fields by forming at least one plating layer on the Cu-based bonding wire and changing the material of the plating layer formed on the outermost layer.

[0008] Other objects and advantages of the present invention may be more clearly explained by the following detailed description of the invention and claims.

[0009]

[0010] To achieve the above-mentioned technical objective, the present invention provides a bonding wire for a semiconductor device comprising: a core material made of a metal or alloy; and at least one plating layer formed on the surface of the core material; wherein the outermost portion of the plating layer is composed of a tin (Sn) plating layer.

[0011] For example, in one embodiment of the present invention, the bonding wire may be applied to an electric semiconductor.

[0012] For example, in one embodiment of the present invention, the core material contains 80 to 99.99 weight percent of copper (Cu), and the remainder may contain at least one of gold (Au), molybdenum (Mo), palladium (Pd), nickel (Ni), cobalt (Co), aluminum (Al), calcium (Ca), silicon (Si), and phosphorus (P).

[0013] For example, in one embodiment of the present invention, the thickness of the tin (Sn) plating layer may be 10 to 300 nm.

[0014] For example, in one embodiment of the present invention, the bonding wire may further include at least one intermediate plating layer among a palladium (Pd) plating layer, a gold (Au) plating layer, and a silver (Ag) plating layer between the core material and the tin (Sn) plating layer.

[0015] For example, in one embodiment of the present invention, the thickness of the intermediate plating layer may be 10 to 100 nm.

[0016] In one embodiment of the present invention, the at least one plating layer may be selected from the group consisting of a tin (Sn) plating layer, a gold (Au) / tin (Sn) plating layer, a palladium (Pd) / tin (Sn) plating layer, and a palladium (Pd) / gold (Au) / tin (Sn) plating layer.

[0017] For example, in one embodiment of the present invention, the thickness ratio of the gold (Au) / tin (Sn) plating layer and the palladium (Pd) / tin (Sn) plating layer may each be 0.05 to 50:1.

[0018] For example, in one embodiment of the present invention, the thickness ratio of the palladium / gold / tin plating layer may be 0.1 to 1 : 0.01 to 0.1 : 1.

[0019]

[0020] According to one embodiment of the present invention, by changing the plating material introduced to the surface of a conventional Cu wire to tin (Sn) instead of palladium (Pd), the possibility of crack occurrence can be reduced by controlling the size of the Cu / Al inter-metallic compound (IMC) formed at the bonding interface between the Cu bonding wire and the aluminum (Al) bonding pad during semiconductor packaging for automotive applications, and reliability can be significantly improved by strengthening the bonding strength.

[0021] In addition, the present invention can improve price competitiveness by reducing the process time and the amount of auxiliary materials input through shortening the existing two-step manufacturing process consisting of Pd plating and Au plating into a single process.

[0022]

[0023] FIG. 1 is a manufacturing process diagram showing a method for manufacturing a bonding wire according to the prior art and an embodiment of the present invention.

[0024] FIG. 2 is a diagram showing the cross-sectional structure of a bonding wire according to Examples 1 to 3 and Comparative Example 1.

[0025] Figure 3 is a binary phase diagram of Al-Cu.

[0026] Figure 4 is a ternary phase diagram of Cu-Al-Sn.

[0027]

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the present invention is not limited to the following embodiments. Throughout this specification, the same reference numerals refer to the same structures.

[0029] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0030] Furthermore, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, and thus the present invention is not necessarily limited to what is illustrated. Thicknesses have been enlarged in the drawings to clearly represent various layers and regions. Additionally, for convenience of explanation, the thickness of some layers and regions has been exaggerated in the drawings.

[0031] Furthermore, throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Also, throughout the specification, the terms "above" or "on" mean that they include not only cases where they are located above or below the subject part but also cases where there is another part in between, and do not necessarily mean that they are located above based on the direction of gravity. Additionally, terms such as "first," "second," etc., in this specification are used to distinguish components from one another, not to indicate an arbitrary order or importance. Furthermore, throughout the specification, "planar" means when the subject part is viewed from above, and "cross-sectional" means when the cross-section obtained by vertically cutting the subject part is viewed from the side.

[0032] Furthermore, as used herein, "preferred" and "preferably" refer to embodiments of the invention that can provide certain advantages under certain conditions. However, other embodiments may also be preferred under the same or different conditions. Additionally, the mention of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

[0033] In the present invention, unavoidable impurities refer to impurities of 100 ppm or less that cannot be avoided during mass production.

[0034] Bonding wire

[0035] One example of the present invention is a bonding wire applied to a semiconductor device, specifically a Cu-based bonding wire applied to a semiconductor device for all automotive electric parts (hereinafter referred to as "electrical parts") mounted in a vehicle.

[0036] Compared to other wires (e.g., Au), Cu-based bonding wires are significantly cheaper and have high strength characteristics, but they have the disadvantage of being less reliable due to their susceptibility to oxidation or corrosion compared to Au wires. Consequently, there have been limitations in applying Cu-based bonding wires to automotive semiconductors, where passenger safety is prioritized even in harsh environments, compared to general electronic devices. To compensate for the low reliability of Cu wires, conventional attempts were made to improve reliability by applying Pd plating with excellent corrosion resistance or by using Cu-based alloy wires; however, there were limitations in improving wire reliability due to ions within the EMC materials present in the semiconductors.

[0037] Accordingly, the present invention is characterized by introducing at least one plating layer on a Cu-based bonding wire, wherein the Pd or Pd / Au material applied as a conventional plating layer is changed to tin (Sn).

[0038] The Sn plating layer introduced into the aforementioned Cu-based bonding wire prevents pitting corrosion caused by S ions in the EMC material and inter-metallic compound (IMC) corrosion between the Al Pad and Cu Wire bonding interfaces caused by Cl ions during semiconductor packaging for automotive applications. Furthermore, it can improve the reliability of semiconductor devices through the excellent bonding strength derived from the Sn material. In particular, Sn is a material primarily used in semiconductor solders; it exhibits excellent bonding strength and has less IMC with Al than Cu, thereby enabling the securing of a synergy effect in reliability through the suppression of IMC formation and enhanced bonding strength.

[0039] Furthermore, by reducing the conventional multi-stage Pd / Au plating process into a single process, it is possible to expect economic benefits and reduced environmental pollution by shortening the process lead time, reducing the space required for equipment, and decreasing the amount of plating auxiliary materials.

[0040] In one specific example, the bonding wire according to the present invention comprises: a core made of copper (Cu) or a copper alloy; and at least one plating layer formed on the surface of the core; wherein the outermost layer of the plating layer is composed of a tin (Sn) plating layer.

[0041] In the bonding wire according to the present invention, the wire core located on the inner side is formed in the shape of a round bar having a constant diameter, and its material is composed of copper (Cu) or an alloy having copper as the main component. Specifically, the core contains a copper (Cu) content of 80 to 99.99 weight%, and the remainder may contain at least one of gold (Au), molybdenum (Mo), palladium (Pd), nickel (Ni), cobalt (Co), aluminum (Al), calcium (Ca), silicon (Si), and phosphorus (P). A more specific example may be Cu-Pd (≤1.0%), Cu-Ca (≤100 ppm)-Al (≤100 ppm), or pure Cu.

[0042] In addition, the present invention includes at least one plating layer formed to surround the wire core, wherein the outermost plating layer is composed of tin (Sn).

[0043] This outermost plating layer can be configured as a tubular structure having a ring-shaped cross-section of substantially uniform thickness that surrounds the outer surface of the bonding wire. Tin (Sn), introduced into the outermost plating layer, is a material primarily used in semiconductor solders and has excellent bonding strength; therefore, it can further enhance the bonding strength between the Cu wire and the Al bonding pad during semiconductor packaging, thereby increasing reliability.

[0044] In addition, since the formation of an inter-metallic compound (IMC) with Sn-Al is relatively less than that with Cu-Al, by changing and distributing a portion of the Cu-Al IMC formed between the interface of the Cu wire and the Al bonding pad during semiconductor packaging to Sn-Al IMC, it is possible to secure a synergistic effect of reducing crack occurrence at the Cu-Al interface and improving reliability by preventing Cu corrosion.

[0045] The thickness of the tin (Sn) plating layer is not particularly limited and can be appropriately adjusted within the conventional range known in the art. For example, it may be 300 nm or less, specifically 10 to 300 nm, and more specifically 15 to 300 nm.

[0046] The bonding wire according to the present invention may further include at least one intermediate plating layer (e.g., an underlayer) between the inner wire core and the tin (Sn) plating layer.

[0047] This intermediate plating layer is formed to surround the outer surface of the inner wire core and may be a tubular structure having a ring-shaped cross-section of substantially uniform thickness. The intermediate plating layer material may be a conventional metal component known in the art, and specifically, may be at least one of a palladium (Pd) plating layer, a gold (Au) plating layer, and a silver (Ag) plating layer.

[0048] The thickness of the above intermediate plating layer is not particularly limited and can be appropriately adjusted within a conventional range known in the art. For example, it may be 400 nm or less, specifically 10 to 200 nm, and more specifically 15 to 100 nm.

[0049] For example, at least one plating layer formed on the copper core may be selected from the group consisting of a tin (Sn) plating layer, a gold (Au) / tin (Sn) plating layer, a palladium (Pd) / tin (Sn) plating layer, and a palladium (Pd) / gold (Au) / tin (Sn) plating layer. The aforementioned plating layers may be arranged sequentially based on the core. In this case, if the tin plating layer is present on the outer surface of the wire, the stacking order, number of layers, and / or stacking structure of other plating layers are not particularly limited and can be freely modified.

[0050] For example, when the plating layer is composed of a single tin (Sn) plating layer, it can improve bonding with adjacent Al bonding pads during semiconductor packaging, reduce IMC, and provide an effect of preventing Cu corrosion.

[0051] As another example, in the case where the above-mentioned at least one plating layer consists of two layers, such as a palladium (Pd) / tin (Sn) plating layer based on the core material, the aforementioned effect attributable to Sn can be achieved, and at the same time, the effect of preventing Cu corrosion due to the Pd plating layer can be achieved.

[0052] In these gold (Au) / tin (Sn) plating layers and / or palladium (Pd) / tin (Sn) plating layers, the thickness ratio of the gold or palladium plating layer to the tin (Sn) plating layer may be 0.01 to 50:1, and specifically 0.05 to 10:1.

[0053] As another example, in the case where at least one of the above plating layers consists of three layers, such as palladium (Pd) / gold (Au) / tin (Sn) plating layers based on the core material, the aforementioned effects of the Sn plating layer and the Pd plating layer are each exhibited, and at the same time, the effect of improving wire processability due to the Au plating layer can be additionally realized.

[0054] In such palladium / gold / tin plating layers, the thickness ratio of the palladium plating layer, the gold plating layer, and the tin plating layer may be 0.01 to 1 : 0.01 to 0.1 : 1, specifically 0.1 to 1 : 0.01 to 0.05 : 1. However, it is not limited thereto.

[0055] As described above, the bonding wire of the present invention is formed with a structure in which a tin outer plating layer surrounds a copper or copper alloy core material, and thus can exhibit ductility and conductivity identical or similar to that of a bonding wire composed of copper or a copper alloy. Furthermore, regardless of the stacking order, number of layers, and / or stacking structure of the intermediate plating layer, it can provide an effect of improving reliability through excellent bonding strength attributed to the tin (Sn) outer plating layer and a reduction in crack occurrence due to changes in the Sn-Al IMC.

[0056] Method for manufacturing bonding wire

[0057] Another example of the present invention is the above-described method for manufacturing a Cu-based bonding wire.

[0058] Hereinafter, a method for manufacturing a bonding wire according to one embodiment of the present invention will be described. However, the method is not limited to the following, and the steps of each process may be modified or selectively combined as needed.

[0059] Generally, wires for semiconductor devices are manufactured through a continuous process of melting / casting, drawing, plating, heat treatment, and winding. In the present invention, the wires can be manufactured according to conventional methods known in the industry, except that two or more steps, such as Pd plating and Au plating, which are conventionally applied in the plating process, are replaced with Sn plating of a single material. For example, a Cu-based bonding wire is manufactured by melting / casting copper (Cu), a conductive metal material, through a drawing process, a plating process, a heat treatment process, and a winding process, wherein the plating process may include a step of forming a film by plating the surface of the Cu wire with Sn.

[0060] One specific example of the above manufacturing method may be configured to include: (i) a step of manufacturing a continuously cast bonding wire by continuously casting a master alloy ('S10'); (ii) a step of first drawing the continuously cast bonding wire to a predetermined diameter ('S20'); (iii) a step of first heat treating the first drawn bonding wire under an inert atmosphere ('S30'); (iv) a step of second drawing the first heat-treated bonding wire ('S40'); (v) a step of plating Sn onto the second drawn bonding wire to form a film ('S50'); (vi) a step of third drawing the Sn-plated bonding wire to a desired diameter ('S60'); (vii) a step of second heat treating under an inert atmosphere ('S70'); and (vi) a step of winding the second heat-treated bonding wire ('S80').

[0061] Meanwhile, FIG. 1 is a schematic process flowchart for manufacturing a Cu-based bonding wire according to one embodiment of the present invention. Hereinafter, with reference to FIG. 1, the manufacturing method is described by dividing it into each process step as follows.

[0062] (i) Manufacturing step of the bonding wire ('Step S10')

[0063] The above S10 step involves producing a continuous casting bonding wire having a predetermined diameter from a conductive raw material using a continuous casting method, specifically by introducing the raw material into a high-frequency melting furnace to produce an ingot through a continuous casting process.

[0064] The conductive raw material may be copper (Cu) or a copper alloy. In this case, the metal components included in the alloy are not particularly limited and may include at least one of the following: ordinary metals known in the art, such as Group 1, Group 2, Group 3 based on the periodic table, transition metals, and / or precious metals. For example, it may contain 80 to 99.99 weight% of copper (Cu), and the remainder may include at least one of gold (Au), molybdenum (Mo), palladium (Pd), nickel (Ni), cobalt (Co), aluminum (Al), calcium (Ca), silicon (Si), and phosphorus (P).

[0065] In addition, copper, a conductive raw material, can have a purity of 99.9% or higher, specifically 99.99% or higher, and more specifically 99.999% or higher.

[0066] If the aforementioned conductive raw material undergoes conventional refining, melting, and casting processes known in the art, a conductive rod or ingot in the form of a rod having a predetermined diameter can be produced. Such a diameter is not particularly limited, but, for example, may be Φ10 mm or less.

[0067] (ii) 1st fresh stage ('S20 stage')

[0068] The above S20 step is a step of processing a conductive rod or ingot to draw (draw) it into a wire shape according to specifications.

[0069] The drawing process is a metalworking method used to produce wires or thin pipes. It involves passing raw metal material through dies with smaller cross-sectional areas and pulling it using mechanical force to reduce the cross-sectional area and lengthen it, thereby transforming it into a wire of the desired shape and size. In other words, a cross-sectional product is obtained that has the same shape and diameter as the diameter of the die through which the raw material passes. This drawing process includes hot drawing and cold drawing, which can be performed individually or in combination.

[0070] As a specific example of the above S20 step, if a conductive raw material copper or copper alloy with a purity of 99.90% or higher is subjected to a primary drawing process using a single die, a conductive raw material of Φ2 to 10 can be processed to a diameter of Φ2 mm or less, and for example, it can be processed to 0.35 to 0.1 mm.

[0071] At this time, the cross-sectional reduction rate of the first fresh stage is 95 to 99%, specifically 98 to 99%. However, it is not specifically limited to this and can be adjusted appropriately considering the desired dimensions.

[0072] (iii) 1st heat treatment step ('S30 step')

[0073] The above S30 step involves applying continuous heat treatment to the primary drawn wire to adjust the physical properties of the wire, which has become hard due to drawing, to a soft state. In addition, processing stress caused by the drawing process can be removed and cracking can be prevented.

[0074] The heat treatment method is not particularly limited, and conventional methods and conditions known in the art may be used. For example, the process may be carried out by passing a wire being transported through a heat treatment facility set to a predetermined temperature. At this time, the heat treatment temperature is not particularly limited and can be appropriately adjusted depending on the wire material used. For example, it may be 200 to 500°C. In addition, to prevent oxidation of the wire, heat treatment may be carried out under an inert atmosphere by continuously injecting Ar, nitrogen gas, etc. into the heat treatment facility.

[0075] (iv) Secondary fresh stage ('S40 stage')

[0076] The above S40 step is a step of processing a wire to a predetermined diameter by performing a second drawing process on a wire that has been heat-treated in the first step.

[0077] In the first drawing stage, a wire with a desired diameter is formed using a single drawing machine, whereas in the second drawing stage, a wire with a desired diameter can be manufactured by passing through a continuous drawing facility in which multiple drawing dies are arranged.

[0078] The conditions of the second drawing process are not particularly limited and can be carried out at a line speed of 100 to 200 m / min. In addition, the cross-sectional reduction rate of the second drawing stage is 50% to 81%, specifically 70% to 81%. However, it is not particularly limited to this and can be adjusted appropriately considering the desired dimensions.

[0079] After undergoing the above second drawing step, the wire can be processed to a diameter of Φ100 μm or less. For example, a wire with a diameter of 10 to 100 μm, specifically 20 to 100 μm, can be obtained.

[0080] (iv-1) Cleaning step ('S40-1 step')

[0081] In order to improve the applicability and uniformity of each plating layer, a wire surface cleaning process may be additionally performed by introducing a dry or wet organic matter removal process at the beginning of the electrolytic plating process line.

[0082] Specifically, the bonding wire is processed in a lubricant (drawing oil) atmosphere to ensure smooth workability during the wire drawing process. The drawing oil used during this wire drawing process contains organic and inorganic impurities; if these impurities remain on the surface of the bonding wire and are introduced into the plating process, the wire plating layer may peel off. This peeled plating layer accelerates wire corrosion or causes wire breakage, thereby reducing the reliability and workability of the bonding wire. To address this, a dry or wet degreasing facility can be installed at the beginning of the plating process described later to thoroughly clean the wire surface, thereby ensuring the formation of a uniform plating layer and preventing peeling of the plating layer during the plating process.

[0083] Here, examples of dry degreasing methods include low-temperature heating drying methods, gas injection methods (e.g., gas blowers), or plasma methods. In addition, examples of wet degreasing methods include ethanol washing methods, electrolytic degreasing, or ultrasonic degreasing. However, they are not particularly limited to these.

[0084] In particular, since the formation of a uniform and robust plating layer is essential for performing multilayer plating in the present invention, surface cleaning can be performed by applying a degreasing method for each plating layer to remove organic matter and impurities from the wire surface.

[0085] Here, organic and inorganic impurities are not specifically limited and may include, for example, carbonaceous organic components, halogen components, and / or inorganic components derived from inorganic acids.

[0086] (v) Plating step ('S50 step')

[0087] The above S50 step is a step of preventing oxidation and improving reliability of the wire by performing Sn-based plating on the secondary drawn Cu bonding wire.

[0088] In particular, the present invention is characterized by replacing the conventional multi-stage process of two or more steps, such as Pd plating and Au plating, with Sn plating, which is a single material. Accordingly, economic efficiency can be improved by shortening the process time required in the existing multi-stage plating process and reducing the amount of plating auxiliary materials used.

[0089] The plating method and conditions employed in the present invention are not particularly limited, and conventional dry / wet plating methods known in the art may be applied without limitation. For example, it may be formed by electroplating, specifically, processing may be carried out with plating current conditions of 50 to 300 A, 20 to 60°C, and winding speed of 10 to 100 mpm, or specifically, with a plating current of 100 to 200 A, a plating temperature of 40 to 50°C, and a winding speed of 30 to 90 mpm. However, it is not particularly limited thereto. The thickness of the Sn plating layer formed in this way is not particularly limited and may be, for example, 300 nm or less.

[0090] If necessary, in the present invention, at least one plating layer among a palladium (Pd) plating layer, a gold (Au) plating layer, and a silver (Ag) plating layer may be further formed before forming the Sn plating layer.

[0091] (vi) 3rd Fresh Stage ('S60 Stage')

[0092] The above S60 step is a step of processing the plated Cu wire to the desired diameter by performing a third drawing process.

[0093] Since the third freshing stage can be applied in the same way as the aforementioned second freshing stage, a separate explanation is omitted.

[0094] After undergoing the above third freshing step, it can be processed to the desired diameter and is not particularly limited.

[0095] (vii) Second heat treatment step ('S70 step')

[0096] The above S70 step is a step of applying heat treatment to the plated Cu bonding wire to adjust its physical and mechanical properties to meet the required specifications. That is, by controlling the heat treatment temperature, residual stress formed inside the bonding wire can be removed, and the strength (breaking load) and elongation can be controlled.

[0097] Since the temperature range and conditions of the above-mentioned second heat treatment step can be applied in the same way as the aforementioned first heat treatment step, a separate explanation is omitted.

[0098] (viii) Winding stage ('S80 stage')

[0099] The above S80 step completes the manufacture of the final product by winding the heat-treated bonding wire onto the winding section.

[0100] At this time, the winding method is not particularly restricted, and conventional winders known in the field may be used. In addition, the spool size, winding direction, and operating conditions can be appropriately adjusted according to customer needs.

[0101] The diameter of the bonding wire manufactured through the above-described method is 10 to 100 μm, specifically 20 to 100 μm. However, it is not particularly limited thereto and can be appropriately adjusted considering the desired dimensions.

[0102] The Cu-based bonding wire according to the present invention, manufactured by the above-described method, can improve reliability by exhibiting excellent bonding strength, improved bonding with Al during semiconductor packaging, reduced IMC, and an effect of preventing Cu corrosion through the introduction of an outer Sn plating layer.

[0103] Accordingly, the above-mentioned Cu-based bonding wire can be applied to conventional electronic devices, semiconductor devices, etc. known in the art, and can be particularly usefully applied to automotive semiconductor devices (vehicle-mounted) that require high reliability even under harsh environments compared to general electronic devices. Furthermore, application to various technical fields requiring high reliability, excellent bonding properties, electrical conductivity, etc., also falls within the scope of the present invention.

[0104] The present invention will be described in detail below through examples, but the following examples and experimental examples are merely illustrative of one form of the present invention, and the scope of the present invention is not limited to the following examples and experimental examples.

[0105]

[0106] [Example 1]

[0107] A conductive metal material (Cu) was melted using high frequency and then continuously cast to a diameter of Φ10.0 mm or less. To reduce the diameter of the continuously cast material, it was processed to a diameter of Φ2.0 mm or less using a drawing process. Subsequently, an intermediate heat treatment was performed at a temperature of 400–500°C under an inert gas atmosphere to remove internal stresses caused by the processing. After the intermediate heat treatment was completed, the drawn material was further processed to a diameter of Φ100 μm or less. For the wire processed to a diameter of Φ100 μm or less, primary degreasing was performed via dry degreasing and secondary degreasing via wet degreasing to improve the plating bonding properties of the bonding wire. The degreasing wire passed through a plating bath, and Sn plating was applied to the wire surface to enhance the reliability and corrosion resistance of the Cu wire. This Sn plating was performed under conditions of a plating current of 100–200 A, a plating temperature of 40–50°C, and a winding speed of 30–90 mpm. After drawing the Sn-plated Cu wire to the finally required wire diameter, heat treatment was performed at 400°C to 600°C for minutes to relieve residual stress inside the wire. The wire, having completed all processing, was wound and packaged to the product registered length.

[0108]

[0109] [Example 2]

[0110] A conductive metal material (Cu) was melted using high frequency and then continuously cast to a diameter of Φ10.0 mm or less. To reduce the diameter of the continuously cast material, it was processed to a diameter of Φ2.0 mm or less using a drawing process. Subsequently, an intermediate heat treatment was performed at a temperature of 400–500°C under an inert gas atmosphere to remove internal stress caused by the processing. After the intermediate heat treatment was completed, the drawn material was further processed to a diameter of Φ100 μm or less. For the wire processed to a diameter of Φ100 μm or less, primary degreasing was performed via dry degreasing and secondary degreasing via wet degreasing to improve the plating bonding properties of the bonding wire. The degreasing wire passed through a plating bath, and Pd plating was applied to the wire surface to enhance the corrosion resistance of the Cu wire. Subsequently, Sn plating was performed sequentially to improve the reliability and corrosion resistance of the Cu wire. This Sn plating was carried out under conditions of a plating current of 100–200A, a plating temperature of 40–50℃, and a winding speed of 30–90 mpm. After the plating was completed, the Cu wire was drawn to the final required wire diameter, and then heat treatment was performed at 400℃ to 600℃ to relieve residual stress inside the wire. The wire, having completed all processing, was wound and packaged to the product-registered length.

[0111]

[0112] [Example 3]

[0113] Conductive metal materials (Cu, Ag, Au, Al) were melted using high frequency and then continuously cast to a diameter of Φ10.0 mm or less. To reduce the diameter of the continuously cast material, the material was processed to a diameter of Φ2.0 mm or less using a drawing process. Subsequently, an intermediate heat treatment was performed at a temperature of 400–500°C under an inert gas atmosphere to remove internal stress caused by the processing. After the intermediate heat treatment was completed, the drawn material was further processed to a diameter of Φ100 μm or less. For the wire processed to a diameter of Φ100 μm or less, primary degreasing was performed via dry degreasing and secondary degreasing via wet degreasing to improve the plating bonding properties of the bonding wire. The degreasing wire was passed through a plating bath. Pd plating was applied to the wire surface to improve the corrosion resistance of the Cu wire, followed by Au plating to improve wire bonding properties. Finally, Sn plating was applied to the surface of the Au plating layer to enhance wire reliability. This Sn plating was carried out under conditions of a plating current of 100–200A, a plating temperature of 40–50℃, and a winding speed of 30–90 mpm. After the plating was completed, the wire was drawn to the final required wire diameter, and then heat treatment was performed at 400℃ to 600℃ to relieve residual stress inside the wire. Once all processing was complete, the wire was wound and packaged to the product-registered length.

[0114]

[0115] [Comparative Example 1]

[0116] A conductive metal material (Cu) was melted using high frequency and then continuously cast to a diameter of Φ10.0 mm or less. To reduce the diameter of the continuously cast material, it was processed to a diameter of Φ2.0 mm or less using a wire drawing process. Subsequently, an intermediate heat treatment was performed at a temperature of 400–500°C under an inert gas atmosphere to remove internal stress generated by the processing. After the intermediate heat treatment was completed, the wire was further drawn to a diameter of Φ100 μm or less. For the wire processed to a diameter of Φ100 μm or less, Pd plating was performed to improve the corrosion resistance of the Cu wire, followed by Au plating to improve machinability. After the plating was completed, the wire was drawn to the final required wire diameter, and then heat treatment was performed to relieve residual stress within the wire. Once all processing was complete, the wire was wound and packaged to the product-registered length.

Claims

1. A core material made of copper (Cu) or a copper alloy; and It includes at least one plating layer formed on the surface of the core material; and A bonding wire for a semiconductor device, wherein the outermost layer of the above plating layer is composed of a tin (Sn) plating layer.

2. In Paragraph 1, Bonding wire applied to automotive semiconductors.

3. In Paragraph 1, The above core material contains a copper (Cu) content of 80 to 99.99 weight%, and A bonding wire comprising at least one of gold (Au), molybdenum (Mo), palladium (Pd), nickel (Ni), cobalt (Co), aluminum (Al), calcium (Ca), silicon (Si), and phosphorus (P).

4. In Paragraph 1, A bonding wire having a tin (Sn) plating layer thickness of 10 to 300 nm.

5. In Paragraph 1, The bonding wire above is located between the core material and the tin (Sn) plating layer, A bonding wire comprising at least one intermediate plating layer among a palladium (Pd) plating layer, a gold (Au) plating layer, and a silver (Ag) plating layer.

6. In Paragraph 5, A bonding wire having an intermediate plating layer thickness of 1 to 100 nm.

7. In Paragraph 1, A bonding wire, wherein at least one plating layer is selected from the group consisting of a tin (Sn) plating layer, a gold (Au) / tin (Sn) plating layer, a palladium (Pd) / tin (Sn) plating layer, and a palladium (Pd) / gold (Au) / tin (Sn) plating layer.

8. In Paragraph 7, A bonding wire in which the thickness ratio of the gold (Au) / tin (Sn) plating layer and the palladium (Pd) / tin (Sn) plating layer is 0.01 to 50:1, respectively.

9. In Paragraph 7, A bonding wire in which the thickness ratio of the above palladium / gold / tin plating layer is 0.1~1 : 0.01~0.1 : 1.

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