Semiconductor devices, bond wire and methods for manufacturing a bond wire

Abstract

Semiconductor device (100), comprising: a semiconductor chip (1); a contact point (2) of the semiconductor chip (1); a first layer (3) lying above the contact point (2), wherein the first layer (3) comprises a material selected from the group consisting of niobium and a niobium and tantalum alloy, wherein a volume percent or weight percent of the one of the niobium and a niobium and tantalum alloy in the first layer (3) is greater than 50 percent of a total volume or weight of the first layer (3); and a connection element (8a, 8b; 15) that is electrically coupled to the contact point (2), wherein the connection element comprises a bond wire (8a, 8b) or a clip (15), wherein the connection element is in direct contact with the contact point (2) and / or the first layer (3).

Description

[0001] The invention relates to semiconductor devices. Additionally, the invention relates to a bonding wire and a method for producing a bonding wire.

[0002] Bond wires can experience oxidation during a bonding process. Furthermore, corrosion of bond wires or migration between bond wires can occur during operation of a device containing the bond wires.

[0003] Semiconductor devices may contain metal layers that can undergo either an oxidation process or a corrosion process.

[0004] Bonding wires, semiconductor devices, and methods for manufacturing these components must be continually improved for high performance, high reliability, and low manufacturing costs. For these and other reasons, there is a need for the present invention.

[0005] US 6,790,757 B1 relates to a wire bonding method for copper connections in semiconductor components. US 2004 / 0 238 955 A1 relates to a semiconductor device and a related manufacturing method. US 6,664,640 B2 relates to a semiconductor device. EP 2 190 013 A2 relates to a connecting wire and a method for manufacturing the same. US 4,954,870 A relates to a semiconductor device. US 6,798,050 B1 relates to a semiconductor device having a semiconductor element mounted on a wiring substrate with a copper pad and a method for manufacturing the same. US 2008 / 0 265 423 A1 relates to a layer structure for corrosion-resistant connecting contacts. The document DE 601 04 470 T2 relates to an electronic component in which high-frequency currents are suppressed and a bonding wire for this purpose.The document US 2002 / 0 113 322 A1 relates to a semiconductor device and a method for its manufacture.

[0006] The accompanying drawings are included to provide a further understanding of embodiments and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain principles of the embodiments. Other embodiments and many of the intended advantages of embodiments will be readily understood as they become better understood by reference to the following detailed description. Fig. 1 schematically illustrates a cross section of a semiconductor device as an exemplary embodiment; Fig. 2 schematically illustrates a cross section of a semiconductor device as another exemplary embodiment; Fig.3 schematically illustrates a cross section of a semiconductor device as another exemplary embodiment; Fig. 4 schematically illustrates a cross section of a semiconductor device as another exemplary embodiment; Fig. 5 schematically illustrates a cross section of a semiconductor device as another exemplary embodiment; Fig. 6 schematically illustrates a cross-section of a portion of a semiconductor device as another exemplary embodiment; Fig. 7 schematically illustrates a cross-section of a portion of a semiconductor device as another exemplary embodiment; Fig. 8 schematically illustrates a cross section of a bonding wire as an exemplary embodiment; Fig.9 schematically illustrates a cross section of a bonding wire as another exemplary embodiment; Fig. 10 schematically illustrates a method for manufacturing a bonding wire as an exemplary embodiment; Fig. 11 schematically illustrates an alloy phase diagram of Cu-Nb; and Fig. Figure 12 schematically illustrates an alloy phase diagram of Nb-Sn.

[0007] Aspects and embodiments are described below with reference to the drawings, wherein like reference numerals are generally used to refer to like elements throughout. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects of the embodiments. However, it may be apparent to one skilled in the art that one or more aspects of the embodiments may be practiced with a lesser level of specific detail. In other instances, well-known structures and elements are shown in schematic form to facilitate describing one or more aspects of the embodiments. The following description is therefore not to be considered limiting. It is noted that the illustration of the various elements in the figures is not necessarily to scale.

[0008] In the following description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration certain embodiments in which the invention may be practiced. In this regard, directional terminology such as, for example, "upper", "lower", "top", "bottom", "left", "right", "front", "back", "vertical", "horizontal", etc. may be used with reference to the orientation of the described figures. Since components of embodiments may be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is by no means limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the concept of the present invention.The features of the various exemplary embodiments described herein may be combined with one another unless expressly stated otherwise.

[0009] As used in this specification, the terms "coupled," "electrically coupled," "connected," or "electrically connected" are not intended to imply that elements must be directly coupled or connected to one another. Intermediate elements may be provided between the "coupled," "electrically coupled," "connected," or "electrically connected" elements.

[0010] The semiconductor devices described below may comprise a semiconductor material such as Si, SiC, SiGe, GaAs, or an organic semiconductor material. The semiconductor material may be used as a semiconductor wafer or semiconductor chip of any type, for example, a power semiconductor chip. The semiconductor chip may comprise integrated circuits, control circuits for controlling integrated circuits, microprocessors, and / or microelectromechanical components. The semiconductor chip may further comprise inorganic and / or organic materials that are not semiconductors, for example, insulators, plastics, or metals.

[0011] The semiconductor devices and bond wires described below comprise a layer containing one of niobium (Nb), tantalum (Ta), and an alloy containing niobium and tantalum. It should be noted that the term "alloy" refers not only to materials commonly referred to as alloys, but is also intended to include materials commonly referred to as "intermetallic materials" or "intermetallic compounds." It should also be noted that the volume percentage or weight percentage of niobium or tantalum in the alloy is not limited to a specific value, but can be any value between 0% and 100%, for example, any of the values ​​10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%.It is understood that the layer may contain other materials, in particular other metals and / or metal alloys with physical and / or chemical properties similar to those of niobium, tantalum, or alloys containing niobium and tantalum. Naturally, the layer may be contaminated by impurities that may arise during the production of the layer. The volume percentage or weight percentage of the one of niobium, tantalum, and an alloy containing niobium and tantalum contained in the layer is not limited to a specific value and is, in particular, greater than half the total volume or total weight of the layer.

[0012] The layer can be used in various ways; for example, it can be arranged over a contact pad (or contact field or contact point or contact area) and / or over a metal layer of a semiconductor chip and / or over a wire core of a bonding wire. The thickness of the layer may depend on its specific application and need not have a constant value, but can vary between arbitrary values. In general, the thickness of the layer can range between 0.5 nanometers and 500 nanometers. In particular, a layer arranged over a wire core can have a reduced thickness between 20 nanometers and 70 nanometers.

[0013] The following table contains approximate physical and chemical properties for the materials tantalum and niobium. Layers containing a mixture of niobium, tantalum, and an alloy containing niobium and tantalum can exhibit similar properties. Characteristic Ta Nb atomic number 73 41 atomic weight 180.95 [g / mol] 92.91 [g / mol] Melting point 2996 [°C] 2468 [°C] boiling point 5458 [°C] 4927 [°C] atomic volume 1.80 · 10 -29 [m 3 ] 1.80 · 10 -29 [m 3 ] Steam pressure at 1800°C 5 · 10 -4 [Well] 7 · 10 -6 [Well] Steam pressure at 2500°C 5 · 10 -3 [Well] 2 · 10 -1 [Well] Density at 20°C 16.60 [g / cm 3 ] 8.56 [g / cm 3 ] Lattice structure body-centered cubic body-centered cubic Lattice constant 330.3 · 10 -12 [m] 329.4 · 10 -12 [m] Hardness at 20°C (cold worked) 120 - 220 [HV10] 110 - 180 [HV10] Hardness at 20°C (recrystallized) 80 - 125 [HV10] 60 - 110 [HV10] Young's modulus at 20°C 186 [GPa] 104 [GPa] Poisson's ratio 0.34 0.35 linear thermal expansion coefficient at 20°C 6.4 · 10 -6 [m / (m·K)] 7.1 · 10 -6 [m / (m·K) ] Thermal conductivity at 20°C 54 [W / (m·K)] 52 [W / (m·K)] specific heat at 20°C 0.14 [J / (g·K)] 0.27 [J / (g·K)] electrical conductivity at 20°C 8 10 -6 [1 / (Ω·m)] 7 · 10 -6 [1 / (Ω·m)] specific electrical resistance at 20°C 0.13 [(Ω·mm 2 ) / m] 0.14 [(Ω·mm 2 ) / m]

[0014] The layer, which comprises one of niobium, tantalum, and an alloy containing niobium and tantalum, can be deposited (or deposited) using various deposition methods (or deposition techniques). For example, the layer can be deposited using a sputtering process in which a gas phase of the material to be deposited is created by ejecting particles from a solid target material into a vacuum. The layer can also be deposited using a vapor deposition process, particularly chemical vapor deposition (CVD) or physical vapor deposition (PVD). In yet another embodiment, the layer can be deposited using an electrodeposition or electroplating process, wherein a component is covered by the layer using an electric field to move metal ions in a solution.

[0015] The production of the layer, which contains a material composed of niobium, tantalum, and an alloy containing niobium and tantalum, is not limited to a specific time. For example, production can be based on wafer-level packaging (WLP) technology, so that the layer is deposited at the wafer level. More specifically, in WLP, the layer can be deposited on a wafer surface and processed before the wafer is sliced ​​into individual semiconductor chips. Alternatively, the layer can be deposited on a single semiconductor chip that has already been sliced ​​from a wafer.

[0016] The semiconductor devices described below may comprise a contact pad, which may consist of or contain a metal, in particular copper. The contact pad may be designed to provide an electrical connection between an integrated circuit of the semiconductor device and a terminal element connected to the contact pad. Options for contacting the contact pad include soldering, wire bonding, clip bonding, flip-chip attachment, and probe needles. The terminal element may therefore be embodied as a bond wire or a bond clip.

[0017] The bonding wires described below may comprise a wire core, which may comprise a metal or a metal alloy, in particular copper or a copper alloy. The wire core may have a thickness between 10 micrometers and 600 micrometers, and in particular between 15 micrometers and 250 micrometers. The wire core may have a substantially round cross-section, so that the term "thickness" of the wire core may refer to the diameter of the wire core.

[0018] The bond wires described below may include a coating material disposed over the wire core. The coating material contains a layer of niobium, tantalum, and an alloy comprising niobium and tantalum. The properties of the coating material (physical and chemical properties, thickness, etc.) may correspond to the properties of similar layers already described in previous paragraphs.

[0019] The bond wires described below may include a passivation layer, for example, an oxide layer. In this context, the term "passivation" may refer to avoiding or preventing oxidation and corrosion of a material disposed beneath the passivation layer. For example, the passivation layer may be created by spontaneous formation of a hard, non-reactive surface film (spontaneous passivation). The passivation layer may have a thickness between 1 nanometer and 10 nanometers, and in particular between 4 nanometers and 8 nanometers.

[0020] Fig.Figure 1 schematically illustrates a cross-section of a semiconductor device 100 as an exemplary embodiment. The semiconductor device 100 comprises a semiconductor chip 1 and a contact pad 2. A first layer 3 is arranged over the contact pad 2, wherein the first layer 3 contains a layer of niobium, tantalum, and an alloy containing niobium and tantalum.

[0021] The contact pad 2 can be made of a material that can undergo oxidation processes. For example, the contact pad 2 can consist of or contain copper, so that an oxidation process can create a layer of copper oxides CuO and / or CuO2 on the surface of the contact pad 2. Due to their low extensibility, such oxide layers can be brittle, which can lead to damage to the oxide layer and the contact pad 2 arranged underneath during or after a bonding process. An oxide layer on the contact pad 2 can therefore make it difficult or even impossible to establish a connection between the contact pad 2 and a connection element. Due to its physical and / or chemical properties, the first layer 3 can protect the contact pad 2 from the aforementioned oxidation processes.Compared to an oxide layer, the first layer 3 can exhibit a higher extensibility value, thus reducing the risk of damage during a bonding process. It should also be noted that tantalum and niobium have electrical conductivities of approximately 8 × 10 -6 [1 / (Ω·m)] or 7 · 10 -6 [1 / (Ω·m)]. The first layer 3 may therefore be suitable for supporting an electrical connection between the contact island 2 and a connecting element coupled thereto.

[0022] The contact island 2 can also be protected by layers that differ in their material composition from the first layer 3. For example, the contact island 2 can be protected by a layer consisting of or containing gold (Au). However, it should be noted that such layers are more expensive than the first layer 3. The contact island 2 can also be protected by a layer consisting of or containing one of nickel (Ni), nickel-palladium (NiPd), nickel-palladium-gold (NiPdAu), and titanium (Ti). In contrast to the first layer 3, such layers are more brittle, which can lead to damage to the layer and a contact island arranged underneath, for example, during a bonding process. In this context, it should be noted that niobium and tantalum have an elastic limit of approximately 550 MPa, while nickel and titanium have elastic limits of approximately 480 MPa and 250 MPa, respectively.It should also be noted that niobium has a Young's modulus at 20°C of about 104 GPa, while nickel and titanium have a Young's modulus at 20°C of about 200 GPa and 120 GPa, respectively.

[0023] Fig.2 schematically illustrates a cross-section of a semiconductor device 200 as another exemplary embodiment. The semiconductor device 200 comprises a semiconductor chip 1 having an active area 4, as well as a metal layer 5 disposed over an opposite (or opposing) area 6 of the semiconductor chip 1, which is opposite (or opposing) to the active area 4. Here, the term "active area" may refer to an area of ​​the semiconductor chip 1 that provides an interaction between the semiconductor chip 1 and its environment. For example, an active area may be an area that includes contact pads that provide an electrical connection between the semiconductor chip 1 and external components.The semiconductor device 200 further comprises a second layer 7 disposed over the metal layer 5, wherein the second layer 7 contains a metal selected from niobium, tantalum, and an alloy containing niobium and tantalum. In . Fig. 2, the metal layer 5 and the second layer 7 cover the entire area of ​​the opposite surface 6. This can occur particularly if the layers were applied at the wafer level, i.e., before the wafer is cut into individual chips. Of course, there may be other embodiments in which the layers do not cover the entire opposite surface, but only parts of it.

[0024] Layers 5 and 7 may have similar characteristics to components 2 and 3 of Fig. 1. For example, layer 7 can protect metal layer 5, which may consist of or contain copper, from oxidation processes. The above remarks regarding components 2 and 3 of Fig. 1 can therefore also be used for the corresponding layers 5 and 7 of Fig. 2 apply. The metal layer 5 can serve to transport heat in a direction away from the semiconductor chip 1 during operation. It should be noted that tantalum and niobium provide good thermal conductivity of approximately 54 [W / (m K)] and 52 [W / (m K)], respectively. Layer 7 therefore also supports heat transport in a direction away from the semiconductor chip 1.

[0025] Fig.3 schematically illustrates a cross-section of a semiconductor device 300 as another exemplary embodiment. The semiconductor device 300 comprises a semiconductor chip 1 having a first surface 4 and a second surface 6 opposite to the first surface 4. A contact pad 2 is arranged over the first surface 4, a first layer 3 is arranged over the contact pad 2, a metal layer 5 is arranged over the second surface 6, and a second layer 7 is arranged over the metal layer 5. Each of the first layer 3 and the second layer 7 contains one of niobium, tantalum, and an alloy containing niobium and tantalum. It should be noted that the device 300 is a combination of the devices 100 and 200 of Fig. 1 and Fig. 2, where like reference numerals refer to like components. Accordingly, statements made in connection with Fig. 1 and Fig.2 also apply to device 300.

[0026] Fig. 4 schematically illustrates a cross-section of a semiconductor device 400 as a further exemplary embodiment. The device 400 comprises a semiconductor chip 1 having an active area with a first contact pad 2a and a second contact pad 2b. The first and second contact pads 2a, 2b are each covered by a first layer 3a, 3b, wherein each of the layers 3a, 3b contains one of niobium, tantalum, and an alloy containing niobium and tantalum. The contact pads 2a, 2b are each electrically coupled to bond wires 8a, 8b and can thereby provide an electrical connection between integrated circuits (not shown) of the semiconductor chip 1 and further components (not shown) connected to the opposite ends of the bond wires 8a, 8b. Fig.4 shows that the layers 3a, 3b are arranged between the contact pads 2a, 2b and the bond wires 8a, 8b, thereby (spatially) separating the components. Of course, the bond wires 8a, 8b may also be in partial or complete (direct) contact with the contact pads 2a, 2b. This is because the layers 3a, 3b can be pushed aside during a bonding process, so that the pushed material can be arranged at least partially on the sidewalls of the end portions 9a, 9b of the bond wires 8a, 8b. The device 400 further comprises a first metallization 10 arranged between the contact pads 2a, 2b and the semiconductor chip 1. A more detailed description of the first metallization 10 will be given in connection with Fig. 6 given.

[0027] A metal layer 5, which, for example, consists of or contains copper, is arranged on the underside of the semiconductor chip 1. The metal layer 5 is covered by a second layer 7, which contains one of niobium, tantalum, and an alloy containing niobium and tantalum. The device 400 further comprises a second metallization 11, which may be similar to the first metallization 10 and is arranged between the semiconductor chip 1 and the metal layer 5. The device 400 is attached to the carrier 12 (e.g., a leadframe) by a layer 13, which may consist of or contain a solder material (e.g., tin) and is arranged between the second layer 7 and a carrier 12. It should be noted that during operation of the device 400, heat may be transported by the components 5, 7, 13, and 12 in a direction away from the semiconductor chip 1.

[0028] Fig.Figure 5 schematically illustrates a cross-section of a semiconductor device 500 as another exemplary embodiment. Device 500 is similar to device 400, but a different technique is used to electrically connect device 500 to a terminal element. Device 500 corresponds to device 400 with respect to first metallization 10 and all components arranged beneath first metallization 10. Fig. 5, the first metallization 10 is covered by a contact pad 2 and a first layer 3 containing a solder material (e.g., tin) made of niobium, tantalum, and an alloy containing niobium and tantalum. A layer 14 consisting of or containing a solder material (e.g., tin) is deposited on the first layer 3 to provide an electrical connection between the semiconductor chip 1 and a bond clip 15, which may consist of or contain copper. Fig.5, the contact island 2 and the layer 3 cover the entire upper surface of the semiconductor chip 1. However, it is understood that the contact island 2 and the layer 3 can also cover only a part of the chip surface.

[0029] Fig. Figure 6 schematically illustrates a cross-section of a portion of a semiconductor device 600 as another exemplary embodiment. Here, the first metallization 10 of Fig.4. The first metallization 10 comprises a plurality of stacked metal layers 16.1 to 16.n, wherein for the sake of simplicity, only two of the metal layers 16.1 to 16.n are illustrated. The spaces between the metal layers 16.1 to 16.n are filled with a dielectric material 20, for example, an oxide. The metal layers 16.1 to 16.n are connected to one another via vias 17, which are arranged substantially perpendicular to the metal layers 16.1 to 16.n. The bottommost metal layer 16.1 is connected to conductive components 18 of the integrated circuits of the semiconductor chip. The conductive components 18 are insulated from further regions by a field oxide 19. As can be seen from Fig.6, the first metallization 10 is designed to provide an on-chip redistribution between components of integrated circuits and the contact island 2. It should be noted that the metal layers 16.1 to 16.n also extend in a direction perpendicular to the cross section of Fig. 6 runs.

[0030] The device 600 further comprises a passivation layer 21, which may consist of or contain silicon nitride and covers the upper surface of the semiconductor chip 1. The passivation layer 21 is open at the location of the contact pad 2, and a barrier layer 22, which may consist of or contain titanium or tungsten (W), is arranged between the first metallization 10 and the contact pad 2 to provide an electrical connection between these components. Similar to Fig.4, the contact island 2 is covered by a layer 3 containing a layer of niobium, tantalum, and an alloy containing niobium and tantalum. In Fig. 6, the upper surface and the side walls of the contact island 2 are covered by the layer 3.

[0031] Fig. Figure 7 schematically illustrates a cross-section of a portion of a semiconductor device 700 as another exemplary embodiment. The device 700 is similar to the device 600. In contrast to Fig. 6, the layer 3 is arranged substantially on the upper surface of the contact island 2, while the side walls of the contact island 2 remain uncovered.

[0032] Fig.8 schematically illustrates a cross-section of a bonding wire 800 as an exemplary embodiment. The bonding wire 800 comprises a wire core 23 and a coating material 24 covering the wire core 23. The coating material 24 includes one of niobium, tantalum, and an alloy containing niobium and tantalum. The diameter d1 of the wire core 23 can have a value between 10 micrometers and 600 micrometers, and in particular between 15 micrometers and 25 micrometers. Furthermore, the thickness d2 of the coating material 24 can in particular have a value of 20 nanometers to 40 nanometers.

[0033] The coating material 24 may provide features already provided in connection with the first layer 3 of Fig.1. For example, the coating material 24 can protect the wire core 23 from oxidation processes that can occur during a bonding process carried out, for example, above a temperature of 150 °C. The wire core 23 can consist of or contain copper, which can lead to a copper oxide layer on the wire core 23. Such oxide layers can be brittle, which can lead to detachment from a contact pad. By applying the coating material 24 to the wire core 23, the formation of oxide layers can be avoided. In addition, the coating material 24 can prevent corrosion effects that can occur between the wire core 23 and other materials of a semiconductor device, for example chemical additives contained in a potting material (i.e., a thermosetting, thermoplastic, or thermosetting material).

[0034] The coating material 24 can further prevent migration of the wire core material between the bond wire 800 and other bond wires located at a short distance. Migration can occur particularly in the case of distances of less than 60 micrometers between the bond wires ("fine pitch"). By applying the coating material 24 to the wire core 23, short circuits between the adjacent bond wires can be avoided. In addition, the coating material 24 can provide a higher extensibility compared to the wire core 23 and / or an oxide layer formed on the wire core 23, so that bonding processes can be improved. It should also be noted that the use of the coating material 24 can provide a well-defined loop building of wire loops, so that it is also possible to avoid wire sweeping.

[0035] There are other ways to prevent oxidation of the wire core 23 during a bonding process. For example, bonding can be performed in an atmosphere of a forming gas. Alternatively, corrosion of the wire core 23 or migration of the wire core material between multiple bond wires can be prevented by coating the wire core 23 with a layer consisting of or containing palladium (Pd). However, it should be noted that a layer of palladium is more expensive than the coating material 24, which contains an alloy of niobium, tantalum, and an alloy comprising niobium and tantalum.

[0036] Fig. Figure 9 schematically illustrates a cross-section of a bond wire 900 as another exemplary embodiment. The bond wire 900 is similar to the bond wire 800 of Fig.8, but additionally comprises a passivation layer 25 disposed over the coating material 24. The thickness d3 of the passivation layer 25 can have a value between 1 nanometer and 10 nanometers, and in particular between 4 nanometers and 8 nanometers.

[0037] Fig. 10 illustrates a method 1000 for manufacturing a bonding wire as an exemplary embodiment. The method 1000 may be used in conjunction with Fig. 8. In a first method step S1, a wire core 23 is provided. In a second method step S2, the wire core 23 is coated with a coating material 24, wherein the coating material 24 contains one of niobium, tantalum, and an alloy containing niobium and tantalum. As already mentioned in previous paragraphs, the process of coating the wire core 23 can comprise one of sputtering, vapor deposition, and electrodeposition.

[0038] In one embodiment, steps S1 and S2 of the method 1000 may be performed to produce insulated bond wires, i.e., bond wires that are not yet incorporated into a device. The produced bond wires, which already comprise the coating material 24, may then later be incorporated into a device. Alternatively, step S1 may be performed first, and the wire core 23 is then incorporated into a device. Thereafter, the already incorporated (i.e., non-insulated) wire core 23 is coated with the coating material 24. It is understood that the method 1000 may include further steps, for example, providing a passivation layer 25 over the coating material 24 (see Fig. 9).

[0039] Fig.Figure 11 schematically illustrates an alloy phase diagram of Cu-Nb, where the temperature T (K) in Kelvin is plotted against the molar ratio Nb / (Cu+Nb). The diagram shows the liquid phase as well as the FCC (face-centered cubic)_A1 and BCC (body-centered cubic)_A2 phases. Fig. 11 it can be seen that layers consisting of or containing copper, as described in the previous paragraphs, can also be replaced by layers consisting of niobium or a Cu-Nb alloy. For example, layer 5 can be Fig. 2 by a niobium layer or a Cu-Nb alloy layer, which according to the phase diagram of Fig. 11 has similar properties.

[0040] Fig.Figure 12 schematically illustrates an alloy phase diagram of Nb-Sn, where the temperature T (K) in Kelvin is plotted against the molar ratio Sn / (Nb+Sn). The diagram shows the liquid phase as well as the phases BCC (body-centered cubic)_A2, Nb-Sn, Nb6Sn5, NbSn2, and NbSn2+Sn (body-centered tetragonal)_A5. Fig. 12 it can be seen that layers consisting of or containing tin as soldering material and described in previous paragraphs can also be replaced by layers consisting of niobium or an Nb-Sn alloy. For example, layer 13 can be Fig. 4 by a niobium layer or a Nb-Sn alloy layer, which according to the phase diagram of Fig. 12 with similar properties.

Claims

[1] A semiconductor device (100) comprising: a semiconductor chip (1); a contact point (2) of the semiconductor chip (1); a first layer (3) overlying the contact point (2), the first layer (3) comprising a material selected from the group consisting of niobium and an alloy comprising niobium and tantalum, wherein a volume percentage or a weight percentage of the one of niobium and an alloy comprising niobium and tantalum in the first layer (3) is greater than 50 percent of a total volume or a total weight of the first layer (3); and a connection element (8a, 8b; 15) which is electrically coupled to the contact point (2), wherein the connection element comprises a bonding wire (8a, 8b) or a clip (15), wherein the connection element is in direct contact with the contact point (2) and / or the first layer (3). [2] The semiconductor device (100) of claim 1, wherein the contact pad (2) comprises copper. [3] The semiconductor device (100) of claim 1 or 2, wherein the first layer (3) has a thickness between 0.5 nanometers and 500 nanometers. [4] Semiconductor device (100) according to one of the preceding claims, wherein the first layer (3) is in direct contact with the contact point (2). [5] Semiconductor device (100) according to one of the preceding claims, wherein the first layer (3) electrically couples the connection element (8a, 8b; 15) and the contact point (2). [6] A semiconductor device (200) comprising: a semiconductor chip (1) comprising an active area (4); a metal layer (5) overlying an opposite surface (6) of the semiconductor chip (1), the opposite surface (6) being opposite the active surface (4), the metal layer (5) comprising copper; a second layer (7) overlying the metal layer (5), the second layer (7) comprising a metal selected from the group consisting of niobium and an alloy comprising niobium and tantalum; and a further layer (13) comprising a solder material and lying directly over the second layer (7), wherein the further layer (13) couples the semiconductor device (200) to a carrier (12). [7] The semiconductor device (200) of claim 6, wherein the second layer (7) has a thickness between 0.5 nanometers and 500 nanometers. [8] A semiconductor device (200) according to claim 6 or 7, wherein the metal layer (5) and the second layer (7) each cover more than half of an area of the opposite surface (6). [9] The semiconductor device (200) according to any one of claims 6 to 8, wherein a volume percentage or a weight percentage of an alloy comprising niobium and an alloy comprising niobium and tantalum in the second layer (7) is greater than 50 percent of a total volume or a total weight of the second layer (7). [10] A semiconductor device (200) according to any one of claims 6 to 9, further comprising: a metallization (11) between the semiconductor chip (1) and the metal layer (5). [11] A semiconductor device (400) comprising: a semiconductor chip (1) comprising a first surface and a second surface opposite the first surface; a contact point (2a, 2b) of the semiconductor chip (1) located above the first surface; a first layer (3a, 3b) lying over the contact point (2a, 2b); a connection element (8a, 8b; 15) electrically coupled to the contact point (2), the connection element comprising a bonding wire (8a, 8b) or a clip (15), the connection element being in direct contact with the contact point (2) and / or the first layer (3); a metal layer (5) lying over the second surface; and a second layer (7) overlying the metal layer (5), the first and second layers each comprising a material selected from the group consisting of niobium and an alloy comprising niobium and tantalum. [12] Bonding wire (800), comprising: a wire core (23); and a coating material (24) disposed over the wire core (23), wherein the coating material (24) comprises a material selected from the group consisting of niobium and an alloy comprising niobium and tantalum, wherein a volume percentage or a weight percentage of the one of niobium and an alloy comprising niobium and tantalum in the coating material (24) is greater than 50 percent of a total volume or a total weight of the coating material (24). [13] The bonding wire (800) of claim 12, wherein the bonding wire (800) comprises copper. [14] Bonding wire (800) according to claim 12 or 13, wherein the wire core (23) has a thickness between 15 micrometers and 250 micrometers. [15] Bonding wire (800) according to one of claims 12 to 14, wherein the coating material (24) has a thickness between 20 nanometers and 70 nanometers. [16] Bonding wire (800; 900) according to one of claims 12 to 15, further comprising: a passivation layer (25) lying over the coating material. [17] Bonding wire (800) according to claim 16, wherein the passivation layer (25) has a thickness between 4 nanometers and 8 nanometers. [18] A method of manufacturing a bonding wire (800), the method comprising: Providing a wire core (23); and Coating the wire core with a coating material (24), wherein the coating material (24) comprises a material selected from the group consisting of niobium and an alloy comprising niobium and tantalum, wherein a volume percentage or a weight percentage of the one of niobium and an alloy comprising niobium and tantalum in the coating material (24) is greater than 50 percent of a total volume or a total weight of the coating material (24). [19] The method of claim 18, wherein coating the wire core (23) comprises sputtering, vapor deposition, or electrodeposition. [20] The method of claim 18 or 19, further comprising forming a passivation layer (25) over the coating material (24).

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