Semiconductor device with heterogeneous solder joint and method of manufacturing the same

Abstract

A method for manufacturing a semiconductor device having a heterogeneous solder joint comprises providing a semiconductor die, providing a coupling element, and soldering the semiconductor die to the coupling element with a first solder joint, the first solder joint comprising a solder material comprising a first metal component and a coating comprising a second metal component different from the first metal component, the coating at least partially covering the solder material, wherein the second metal component has a greater stiffness and / or a higher melting point than the first metal component.

Description

Technical Field

[0001] This disclosure generally relates to a semiconductor device having a heterogeneous welded joint and a method for manufacturing such a semiconductor device. Background Technology

[0002] Semiconductor devices, such as semiconductor packages, include solder joints that electrically couple the various components of the semiconductor device to each other. Solder joint failures, such as solder creep, solder leakage, or cracks, can impair the electrical function of the semiconductor device. For example, the resistance of the solder joint may increase or a short circuit may occur. Such failures are particularly problematic in power semiconductor devices configured to operate at high currents and / or high voltages. For these and other reasons, there is a need to provide semiconductor devices with improved solder joints and improved methods for manufacturing semiconductor devices. Summary of the Invention

[0003] Various aspects relate to a method for manufacturing a semiconductor device having a heterogeneous solder joint, the method comprising: providing a semiconductor die, providing a coupling element, and soldering the semiconductor die to the coupling element with a first solder joint, the first solder joint comprising: a solder material comprising a first metallic component and a coating comprising a second metallic component different from the first metallic component, the coating at least partially covering the solder material, wherein the second metallic component has greater stiffness and / or a higher melting point than the first metallic component.

[0004] Various aspects relate to a semiconductor device having a heterogeneous solder joint, the semiconductor device comprising: a semiconductor die, a coupling element, and a first solder joint coupling the semiconductor die to the coupling element, the first solder joint comprising: a solder material comprising a first metallic component and a coating comprising a second metallic component different from the first metallic component, the coating at least partially covering the solder material, wherein the second metallic component has greater stiffness and / or a higher melting point than the first metallic component. Attached Figure Description

[0005] The accompanying drawings illustrate examples and, together with the detailed description, serve to explain the principles of this disclosure. Other examples and numerous anticipated advantages of this disclosure become more readily understood, and thus are made easier to grasp, through reference to the following detailed description. The elements in the drawings are not necessarily to scale. The same reference numerals denote corresponding identical or similar parts.

[0006] Figure 1 A cross-sectional view of a semiconductor device is shown, which includes semiconductor dies and coupling elements coupled to each other via heterogeneous bonding joints.

[0007] Figure 2A detailed view of a heterogeneous welded joint, including solder material and a coating covering at least the lateral side of the solder material, is shown.

[0008] Figure 3A and 3B A detailed view of another semiconductor device is shown, in which a heterogeneous solder joint is arranged on a spacer element.

[0009] Figure 4A and 4B A cross-sectional view of another semiconductor device is shown, in which a heterogeneous bonding joint can be arranged between a semiconductor die and a contact clip. Figure 4A ) or between two semiconductor dies ( Figure 4B ).

[0010] Figures 5A to 5F Cross-sectional views of a semiconductor device are shown at various stages of manufacturing according to an exemplary method for manufacturing a semiconductor device.

[0011] Figure 6 This is a flowchart of an exemplary method for manufacturing semiconductor devices. Detailed Implementation

[0012] In the following detailed description, directional terms such as "top," "bottom," "left," "right," "upper," and "lower" are used with reference to the orientation of the accompanying drawings. Because the components of this disclosure can be positioned in multiple different orientations, the directional terms are used for illustrative purposes only.

[0013] With regard to the terms “comprising,” “having,” “with,” or other variations thereof used in the detailed description or claims, such terms are intended to contain in an open-ended manner similar to the term “comprising.” The terms “coupled” and “connected” and their derivatives may be used. It should be understood that these terms can be used to indicate that two elements cooperate or interact with each other, whether they are in direct physical or electrical contact, or whether they are not in direct contact with each other; an intermediary element or layer may be provided between elements that are “joined,” “attached,” or “connected.” However, elements that are “joined,” “attached,” or “connected” may also be in direct contact with each other. Furthermore, the term “exemplary” is intended only as an example, not as the best or optimal.

[0014] The examples of semiconductor devices described below can use various types of semiconductor chips or circuits incorporated within semiconductor chips, such as AC / DC or DC / DC converter circuits, power MOS transistors, power Schottky diodes, JFETs (junction-gate field-effect transistors), power bipolar transistors, logic integrated circuits, analog integrated circuits, power integrated circuits, chips with integrated passive devices, etc. These examples can also use semiconductor chips comprising MOS transistor structures or vertical transistor structures, such as IGBT (Insulated Gate Bipolar Transistor) structures or more generally, transistor structures in which at least one electrical contact pad is arranged on a first main surface of the semiconductor chip and at least one other electrical contact pad is arranged on a second main surface of the semiconductor chip opposite to the first main surface.

[0015] Furthermore, one or more logic integrated circuits may be included in the device. The logic integrated circuits may be configured to control other semiconductor dies, such as power semiconductor dies. The logic integrated circuits may be implemented as logic dies.

[0016] Figure 1 A semiconductor device 100 is shown, comprising a semiconductor die 110, a coupling element 120, and a first solder joint 130 coupling the semiconductor die 110 to the coupling element 120. The first solder joint 130 includes a solder material 131 comprising a first metallic component and a coating 132 comprising a second metallic component, wherein the second metallic component differs from the first metallic component. Furthermore, the second metallic component has greater stiffness and / or a higher melting point than the first metallic component. The coating 132 at least partially covers the solder material 131.

[0017] Semiconductor die 110 may include a first side 111 and an opposite second side 112, and coupling element 120 may also include a first side 121 and an opposite second side 122. Semiconductor die 110 and coupling element 120 may be arranged relative to each other such that the first sides 111, 121 face each other. A first solder joint 130 may be disposed between the first sides 111, 121. A first side 133 of the first solder joint 130 may face the semiconductor die 110 and an opposite second side 134 may face the coupling element 120. The first solder joint may also include a lateral side 135 connecting the first and second sides 133, 134.

[0018] Semiconductor device 100 may include an encapsulation material that at least partially encapsulates semiconductor die 110 and may also encapsulate coupling element 120. The encapsulation material may include polymeric materials, such as molded bodies, top encapsulants, laminates, and / or plastic frames. The encapsulation material may also include inorganic materials, such as cement or glass-based materials. According to one example, coupling element 120 may be at least partially exposed on the outside of the encapsulation material to provide external terminals for semiconductor device 100 and / or to dissipate heat from semiconductor die 110.

[0019] Semiconductor die 110 may be a power semiconductor die configured to operate at high current and / or high voltage. Semiconductor die 110 may include a first power terminal (e.g., source terminal, drain terminal, emitter terminal, or collector terminal) on its first side 111, and a first solder joint 130 may be disposed on and electrically coupled to the first power terminal. Semiconductor die 110 may include a second power terminal on the first side 111 or on a second side 112, and additional first solder joints may be disposed on and electrically coupled to the second power terminal.

[0020] According to one example, coupling element 120 includes one or more of a die carrier, electrical connector, contact clip, heat sink, lead frame or lead frame component, DCB (direct copper bonding), DAB (direct aluminum bonding), AMB (active metal bonding), PCB (printed circuit board), and other semiconductor dies. Coupling element 120 can be electrically coupled to semiconductor die 110 via a first solder joint 130. Coupling element 120 can be configured to: provide mechanical support for semiconductor die 110, dissipate heat from semiconductor die 110, and / or be part of a circuit along with semiconductor die 110.

[0021] The first weld joint 130 can have any suitable size and can cover any suitable portion of the first side 111 of the semiconductor die 110, for example, covering about 5%, 10%, 20%, 50%, 70%, or close to 100% or 100%. The semiconductor device 100 may include a single first weld joint 130 or more than one first weld joint 130. When the semiconductor device 100 includes more than one first weld joint 130, the first weld joints 130 may have the same size and / or the same material composition, or the individual first weld joints 130 may have different sizes and / or different material compositions.

[0022] According to one example, one or more intermediary elements are disposed between the first solder joint 130 and the semiconductor die 110. The intermediary elements may, for example, comprise intermediary layers and / or spacer elements. The one or more intermediary layers may, for example, comprise diffusion barrier layers, contact layers, anti-corrosion layers, etc. The one or more intermediary layers may, for example, comprise one or more of W, Tu, Al, Ni, Pd, Pt, and Ti. The spacer elements may, for example, comprise metal pillars, particularly pillars comprising or composed of Al, Cu, or any other suitable metal or metal alloy.

[0023] The first solder joint 130, particularly the solder material 131, may include, for example, a soft solder material, such as Sn. The solder material 131 may include one or more other metallic components, such as Ag. According to one example, the amount of Ag is about 1.8%. The first solder joint 130, particularly the first metallic component, may additionally include the material of the metallized portion of the semiconductor die 110 and / or the metallic material of the coupling element 120.

[0024] The second metallic component of coating 132 may include any suitable metal configured to provide coating 132 with greater stiffness and / or a higher melting point than solder material 131. According to one example, the second metallic component includes or consists of one or more of NiSn, CuSn, ZnSn, SbSn, BiSn, AgSn, CoSn, SiSn, CuNiSn, and CuPdSn. Coating 132 may be particularly different from the simple oxide layer of solder material 131. Due to the different material compositions of solder material 131 and coating 132, the first weld joint 130 may be referred to as a "heterogeneous weld joint".

[0025] Coating 132 may be disposed, for example, on the lateral side 135 of the first solder joint 130. Specifically, coating 132 may completely cover all lateral sides 135. According to one example, coating 132 may additionally be disposed on the second side 134 facing the coupling element 120. Coating 132 may partially or completely cover the second side 134. According to one example, coating may cover, particularly partially or completely cover, the first side 133 facing the semiconductor die 110. Portions of coating 132 on the lateral side 135 and portions of coating 132 on the second side 134 or the first side 133 may have different material compositions. For example, the materials of solder material 131 and coupling element 120 may react with each other and possibly also with the material of coating 132 compared to the material composition of coating 132 on the lateral side 135, and this may thereby change the material composition of coating 132 on the second side 134 or the first side 133.

[0026] According to one example, the semiconductor device 100 includes more than one semiconductor die 110 and / or more than one coupling element 120, and at least some of these semiconductor dies 110 and coupling elements 120 are connected to each other via a first solder joint 130.

[0027] According to one example, the semiconductor device 100 may include one or more second weld joints, wherein the one or more second weld joints have a different composition from the first weld joint 130. For example, the one or more second weld joints may not have a coating 132.

[0028] Figure 2 A schematic cross-sectional view of the first welded joint 130 is shown in more detail. Figure 2 In the example, the coating only covers the lateral side 135 of the first weld joint 130, without covering the first side 133 or the second side 134. However, as described above, the coating 132 may also cover the second side 134, for example.

[0029] The height h of the first welded joint 130, measured between the first side 133 and the second side 134, can be, for example, several micrometers, such as about 5 μm or more, 10 μm or more, 20 μm or more, 50 μm or more, or 100 μm or more. The thickness t of the coating 132 can be, for example, in the nanometer range or in the micrometer range. The thickness t can be, for example, about 10 nm or more, 20 nm or more, 50 nm or more, 100 nm or more, 200 nm or more, 500 nm or more, 1 μm or more, 2 μm or more, or 5 μm or more.

[0030] The first weld joint 130 is not required to have Figure 2 The shape is shown in the schematic diagram. For example, the first weld joint 130 may have a cylindrical shape, a dome shape, a flat shape, a concave shape, a convex shape, and its lateral side 135 may have a crescent shape, etc. According to one example, at least one side of the first weld joint 130 is not covered by the coating 132, while at least one other side, or at least two other sides, or all other sides are covered by the coating 132.

[0031] Figure 3A and 3B Detailed views of semiconductor devices 300 and 300' are shown, which may be similar to or the same as semiconductor device 100, except for the differences described below. In particular, semiconductor devices 300 and 300' include spacer elements 310 disposed between semiconductor die 110 and first solder joint 130.

[0032] exist Figure 3A and 3BIn the example shown, the spacer element 310 includes a metal pillar, such as a Cu pillar, an Al pillar, an Au pillar, etc. The spacer element 310 can have any suitable size, for example, a length l of 20 μm or more, 50 μm or more, 100 μm or more, 200 μm or more, 500 μm or more, or 1 mm or more.

[0033] The first weld joint 130 can be directly disposed on the spacer element 310. However, one or more intervening layers can also be disposed between the spacer element 310 and the first weld joint 130. For example, a first intervening layer 320 and a second intervening layer 330 can be disposed between the first weld joint 130 and the spacer element 310. The first intervening layer 320 can, for example, comprise or be composed of Ni. The second intervening layer 330 can, for example, comprise or be composed of Cu or Pd.

[0034] In semiconductor device 300, coupling element 120 includes a first metallization layer 340 and a second metallization layer 350 facing the first bonding joint 130. However, semiconductor device 300 may also include only the first metallization layer 340 or only the second metallization layer 350. The first metallization layer 340 may, for example, include or be composed of Ni. The second metallization layer 350 may, for example, include Cu or Pd or be composed of them. Providing the first and / or second metallization layers 340, 350 may, for example, include a plating operation over coupling element 120. The first and / or second metallization layers 340, 350 may, for example, have a thickness in the range of 3 nm to 1.5 μm, such as about 15 nm, about 25 nm, about 50 nm, about 100 nm, or about 500 nm.

[0035] In semiconductor device 300', coupling element 120 does not include a metallization layer. Alternatively, the first solder joint is disposed directly on the bulk of coupling element 120. In this case, coupling element 120 may, for example, comprise or be composed of Cu. The surface of coupling element 120 may, for example, include structured structures, such as pits or etched structures. Such structured portions may, for example, improve the adhesion of the first solder joint 130.

[0036] Figure 3A and 3B The coating 132 is shown to be disposed only on the lateral side 135 of the first weld joint 130. However, as previously mentioned, the coating 132 may also be disposed on the second side 134, for example. According to one example, the coating 132 only partially covers the second side 134, allowing the solder material 131 to be in direct contact with the coupling element 120.

[0037] Figure 4A and 4BAdditional semiconductor devices 400 and 400' that may be similar to or the same as semiconductor devices 100, 300 and 300' are shown.

[0038] Semiconductor device 400 includes a semiconductor die 110, a coupling element 120, and an additional coupling element 410. The additional coupling element 410 may be of a similar or identical type to coupling element 120, such as an additional DCB or lead frame component or PCB, or as... Figure 4A The contact clip is shown. Coupling element 120 can be arranged facing a first side 111 of semiconductor die 110, while another coupling element 410 can be arranged facing a second side 112 of semiconductor die 110. In other words, semiconductor die 110 can be arranged between coupling elements 120 and 410.

[0039] The additional coupling element 410 may be coupled to the semiconductor die 110 via the first solder joint 130, similar to coupling element 120. The additional coupling element 410 may include or be composed of the same material or material composition as coupling element 120, such as copper, nickel, or palladium. Furthermore, the additional coupling element 410 may include one or more metallization layers, similar to those referenced above. Figure 3A The first and second metallization layers 340 and 350 are described. However, the additional coupling element 410 may also include or be composed of a different material or material composition than the coupling element 120.

[0040] Semiconductor device 400 includes a first solder joint 130 coupling coupling elements 120, 410 to semiconductor die 110, and may also include another first solder joint 130 coupling another coupling element 410 to a contact member 420. For example, the additional coupling element 410 may be a contact clip and the contact member 420 may be a contact portion of semiconductor device 400, such as an internal or external contact portion. More generally, the first solder joint 130 is not necessarily disposed on semiconductor die 110, but may be disposed between any two suitable conductive parts of the semiconductor device.

[0041] According to one example, a spacer element, such as spacer element 310, may be arranged between the semiconductor die 110 and another coupling element 410. The spacer element may be specifically arranged between the semiconductor die 110 and a first solder joint 130 that couples the other coupling element 410 to the semiconductor die 110.

[0042] Figure 4BThe semiconductor device 400' shown includes a semiconductor die 110 and another semiconductor die 430 disposed on a second side 112 of the semiconductor die 110. A first bonding joint 130 couples the other semiconductor die 430 to the semiconductor die 110. The other semiconductor die 430 may be, for example, a power semiconductor die. The semiconductor dies 110 and 430 may, for example, be coupled together to form a circuit similar to a half-bridge circuit.

[0043] According to one example, a spacer element, such as spacer element 310, can be disposed between semiconductor dies 110 and 430. The spacer element can be disposed directly on the second side 112 of semiconductor die 110, and a first solder joint 130 can be disposed on the top of the spacer element. According to another example, the spacer element can be disposed directly on the lower side 431 of another semiconductor die 430, and the first solder joint 130 can be disposed between the spacer element and the first side 112 of semiconductor die 110.

[0044] Figures 5A to 5F Semiconductor device 500 at different manufacturing stages is shown according to an exemplary method for manufacturing semiconductor devices. Similar methods can be used to manufacture semiconductor devices 100, 300, 300', 400, and 400'.

[0045] like Figure 5A As shown, a semiconductor die 110 is provided. According to one example, the semiconductor die 110 is still part of a semiconductor wafer. According to another example, a monolithic die is provided. The semiconductor die 110 can be a thinned die, meaning that, for example, a back-side polishing process is used to reduce the thickness of the semiconductor die 110.

[0046] like Figure 5B As shown, one or more spacer elements 310 are fabricated on a semiconductor die 110. Fabricating spacer elements 310 may, for example, include plating onto the semiconductor die 110. Spacer elements 310 may be fabricated on a first side 111, a second side 112, or on both sides of the first and second sides 111, 112 of the semiconductor die 110.

[0047] The operation of manufacturing spacer element 310 is optional; if a semiconductor device without spacer element is to be manufactured, spacer element 310 is not provided on semiconductor die 110.

[0048] According to one example, after fabricating spacer element 310, one or more intermediary layers, such as intermediary layers 320, 330, are fabricated on spacer element 310. This may include, for example, plating on spacer element 310. According to another example, no intermediary layer is provided.

[0049] like Figure 5CAs shown, solder deposit 510 is deposited on spacer element 310. Alternatively, in the absence of spacer element 310, solder deposit 510 is deposited on semiconductor die 110.

[0050] Solder deposit 510 may include solder material 131 or a precursor of solder material 131. However, according to one example, solder deposit 510 does not include the material of coating 132.

[0051] like Figure 5D As shown, solder deposit 510 is immersed in a pool 520 containing an ionic liquid to form a precursor for coating 132 on the solder deposit 510. A metal salt, such as an inorganic metal salt, is dissolved in the ionic liquid (which can act as a co-solvent system) and the metal salt contains a metallic component for forming the coating precursor. The metal salt can be, for example, an ammonium carbonate, bicarbonate, formate, or an amine salt.

[0052] According to one example, the metal salt includes one or more of copper ammonium carbonate, cobalt ammonium carbonate, nickel ammonium carbonate, antimony acetate, bismuth acetate, and zinc acetate. According to one example, the ionic liquid includes alkylimidazolium carboxylates or alkyl ammonium carboxylates. Ionic liquids may, for example, have a melting point below 20°C and a boiling point in the range of 100°C to 200°C. The metal salt may be contained in the ionic liquid at any suitable concentration.

[0053] Solder deposit 510 can be immersed in pool 520 for any suitable duration, such as 1 second or more, 5 seconds or more, 10 seconds or more, 30 seconds or more, 1 minute or more, 5 minutes or more, or 10 minutes or more. The ionic liquid in pool 520 can have any suitable temperature, such as room temperature or can be heated to above room temperature. The coating precursor can be formed, for example, at a temperature below the liquidus temperature of solder material 131. The ionic liquid can act as a co-solvent for the metal salt and the organic flux. The organic flux may contain organic acids and thickeners.

[0054] According to one example, the pool 520 with an ionic liquid is configured as a flux. In the case where the ionic liquid contains chloride or fluoride anions, it can not only provide a coating precursor but also remove the oxide layer from the solder deposit 510. In other words, both functions can be performed simultaneously by the pool 520.

[0055] Figure 5E This illustrates the manufacturing stage after the solder deposit 510 has been immersed in the bath 520. A coating precursor 530 has been formed on the surface of the solder deposit 510. The coating precursor 530 may have a different material composition than the finished coating 132.

[0056] like Figure 5FAs shown, a semiconductor die 110 is soldered (e.g., reflow soldered) to a coupling element 120, thereby forming a first solder joint 130. Soldering may include applying heat to the solder deposit 510 and the coating precursor 530. Soldering may include transforming the coating precursor 530 into a coating 132. This transformation may be due to heat applied to the coating precursor 530. According to one example, the heating operation forms a coating by reducing metal salts present in the coating precursor 530 to metals or metal oxides (possibly along with N and / or CO2). Any oxides present are cleaned in situ by flux. Thus, a second metallic component of the coating 132 can be formed.

[0057] According to one example, the coating precursor 530 is transformed into coating 132 at a temperature below the liquidus temperature of solder material 131. Coating 132 may also have a higher melting point and / or greater stiffness than solder material 131 (i.e., the second material composition of coating 132 may, for example, have a greater Young's modulus than the first material composition of solder material 131). Thus, coating 132 can act as a barrier, which can, for example, prevent solder seepage or solder creep. In other words, coating 132 can be configured as a reinforcing structure of the first weld joint 130.

[0058] For example, the coating precursor can be transformed into coating 132 at a temperature ranging from 180°C to 220°C. The liquidus temperature of solder material 131 can be, for example, in the range of 200°C to 260°C.

[0059] According to another example, the coating precursor 530 is transformed into coating 132 at approximately the liquidus temperature of solder material 131.

[0060] As an example, welding operations involve the use of a syngas, such as a syngas containing N and H. The syngas can promote the reduction of metal salts into metals.

[0061] Figure 6 This is a flowchart of a method 600 for manufacturing a semiconductor device. Method 600 can be used, for example, to manufacture semiconductor devices 100 to 500.

[0062] In step 601, method 600 includes providing a semiconductor die, in step 602 it includes providing a coupling element, and in step 603 it includes soldering the semiconductor die to the coupling element with a first solder joint, the first solder joint comprising: a solder material comprising a first metallic component and a coating comprising a second metallic component different from the first metallic component, the coating at least partially covering the solder material, wherein the second metallic component has greater stiffness and / or a higher melting point than the first metallic component.

[0063] According to one example of method 600, a coating precursor is used to cover solder material before the semiconductor die is soldered to the coupling element, and soldering the semiconductor die to the coupling element also includes converting the coating precursor into a coating, for example by applying heat and thereby causing a reduction reaction in the coating precursor.

[0064] Example

[0065] The following sections use specific examples to further explain semiconductor devices and methods for manufacturing them.

[0066] Example 1 is a method for manufacturing a semiconductor device having a heterogeneous solder joint, the method comprising: providing a semiconductor die, providing a coupling element, and soldering the semiconductor die to the coupling element with a first solder joint, the first solder joint comprising: a solder material comprising a first metallic component and a coating comprising a second metallic component different from the first metallic component, the coating at least partially covering the solder material, wherein the second metallic component has a greater stiffness and / or a higher melting point than the first metallic component.

[0067] Example 2 is based on the method of Example 1, wherein a coating precursor is used to cover solder material before the semiconductor die is soldered to the coupling element, and soldering the semiconductor die to the coupling element further includes converting the coating precursor into a coating.

[0068] Example 3 is the method according to Example 2, the method further comprising: depositing solder material on a semiconductor die or coupling element, and then covering the deposited solder material with a coating precursor.

[0069] Example 4 is the method according to Example 2 or 3, wherein bonding the semiconductor die to the coupling element includes heating the deposited solder material to melt the deposited solder material, and the operation of heating the deposited solder material forms a coating of a second metallic component from the coating precursor.

[0070] Example 5 is based on the method of Example 4, wherein the operation of heating the deposited solder material forms a coating by reducing the metal present in the coating precursor to form a second metal component.

[0071] Example 6 is a method according to any one of Examples 2-5, wherein the coating precursor is a flux containing a metal dopant.

[0072] Example 7 is a method according to any one of Examples 2-6, wherein the solder material is immersed in a pool containing an ionic liquid in order to form the coating precursor.

[0073] Example 8 is based on the method of Example 7, wherein an inorganic metal salt is dissolved in an ionic liquid, and the metallic component of the inorganic metal salt is used to form a coating.

[0074] Example 9 is the method according to Example 8, wherein the inorganic metal salt comprises one or more of copper ammonium carbonate, cobalt ammonium carbonate, nickel ammonium carbonate, antimony acetate, bismuth acetate, and zinc acetate.

[0075] Example 10 is a method according to any one of Examples 7-9, wherein the ionic liquid comprises an alkylimidazolium carboxylate or an alkylammonium carboxylate.

[0076] Example 11 is a method according to any one of Examples 2-10, wherein the coating precursor is formed at a temperature below the liquidus temperature of the solder material.

[0077] Example 12 is a method according to any of the preceding examples, wherein the coating is formed around the solder material such that the solder material is prevented from overflowing from the weld joint by the coating.

[0078] Example 13 is a semiconductor device having a heterogeneous solder joint, the semiconductor device comprising: a semiconductor die, a coupling element, and a first solder joint coupling the semiconductor die to the coupling element, the first solder joint comprising: a solder material comprising a first metallic component and a coating comprising a second metallic component different from the first metallic component, the coating at least partially covering the solder material, wherein the second metallic component has greater stiffness and / or a higher melting point than the first metallic component.

[0079] Example 14 is a semiconductor device according to Example 13, wherein the coupling element includes one or more of a die carrier, contact clip, lead frame, DCB, DAB, PCB or other semiconductor die.

[0080] Example 15 is a semiconductor device according to Example 13 or 14, wherein the first solder joint includes a first side facing the semiconductor die, an opposite second side facing the coupling element, and a lateral side connecting the first side and the second side, the coating covering the lateral side but not the first side.

[0081] Example 16 is a semiconductor device according to any one of Examples 13-15, wherein the thickness of the coating is in the range of 10 nm to 5 μm.

[0082] Example 17 is a semiconductor device according to any one of Examples 13-16, wherein the first metal component includes Sn.

[0083] Example 18 is a semiconductor device according to any one of Examples 13-17, wherein the second metal component includes one or more of NiSn, CuSn, ZnSn, SbSn, BiSn, AgSn, CoSn, SiSn, CuNiSn and CuPdSn.

[0084] Example 19 is a semiconductor device according to any one of Examples 13-18, the semiconductor device further comprising: a metal pillar disposed on a semiconductor die, wherein a first solder joint is disposed on the metal pillar.

[0085] Example 20 is an apparatus that includes means for performing a method according to any one of Examples 1-12.

[0086] While this disclosure has been illustrated and described with respect to one or more embodiments, changes and / or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. In particular, with respect to the various functions performed by the aforementioned components or structures (components, devices, circuits, systems, etc.), unless otherwise stated, the terminology used to describe such components (including references to “device”) is intended to correspond to any component or structure that performs the specified function of the described component (e.g., functionally equivalent), even if structurally not equivalent to the disclosed structure that performs that function in the exemplary embodiments of this disclosure shown herein.

Claims

1. A method for manufacturing a semiconductor device (100) having a heterogeneous bonding joint, the method comprising: Provide semiconductor bare dies (110). Provides a coupling element (120), and The semiconductor die (110) is soldered to the coupling element (120) using a first solder joint (130), the first solder joint (130) comprising: Solder material (131) including the first metallic component, and A coating (132) comprising a second metal component different from the first metal component, the coating (132) at least partially covering the solder material (131). The second metal component has greater stiffness and / or a higher melting point than the first metal component; Before soldering the semiconductor die (110) to the coupling element (120), a coating precursor (530) is used to cover the solder material (131). The process of soldering the semiconductor die (110) to the coupling element (120) further includes converting the coating precursor (530) into a coating (132) and heating the deposited solder material (131) to melt the deposited solder material (131). The process of heating and depositing solder material (131) forms a coating (132) by reducing the metal present in the coating precursor (530) to form a second metal component.

2. The method according to claim 1, wherein, The method further includes: Solder material (131) is deposited on the semiconductor die (110) or on the coupling element (120), and The deposited solder material (131) is then covered with a coating precursor (530).

3. The method according to claim 1 or 2, wherein, The coating precursor (530) is a flux containing metal dopants.

4. The method according to claim 1 or 2, wherein, The solder material (131) is immersed in a pool (520) containing an ionic liquid in order to form the coating precursor (530).

5. The method according to claim 4, wherein, An inorganic metal salt is dissolved in the ionic liquid, and the metallic component of the inorganic metal salt is used to form a coating (132).

6. The method according to claim 5, wherein, The inorganic metal salts include one or more of the following: ammonium copper carbonate, ammonium cobalt carbonate, ammonium nickel carbonate, antimony acetate, bismuth acetate, and zinc acetate.

7. The method according to claim 5 or 6, wherein, The ionic liquid includes alkylimidazolium carboxylate or alkylammonium carboxylate.

8. The method according to any one of claims 1-2 and 5-6, wherein, The coating precursor (530) is formed at a temperature lower than the liquidus temperature of the solder material (131).

9. The method according to any one of claims 1-2 and 5-6, wherein, The coating (132) is formed around the solder material (131) to prevent the solder material (131) from overflowing from the weld joint (130).

10. A semiconductor device (100) having a heterogeneous welded joint, the semiconductor device (100) comprising: Semiconductor die (110). Coupler element (120), and A first solder joint (130) couples the semiconductor die (110) to the coupling element (120), the first solder joint (130) comprising: Solder material (131) including the first metallic component, and A coating (132) comprising a second metal component different from the first metal component, the coating (132) at least partially covering the solder material (131). The second metallic component has greater stiffness and / or a higher melting point than the first metallic component. The first welded joint (130) includes a lateral side (135), which is covered by a coating (132). The thickness of the coating (132) measured perpendicular to the lateral side (135) is in the range of 10 nm to 5 μm.

11. The semiconductor device (100) according to claim 10, wherein, The coupling element (120) includes one or more of a die carrier, contact clip, lead frame, DCB, DAB, PCB and other semiconductor dies.

12. The semiconductor device (100) according to claim 10 or 11, wherein, The first weld joint (130) has a first side (133) facing the semiconductor die (110) and an opposite second side (134) facing the coupling element (120), wherein a lateral side (135) connects the first side and the second side (133, 134), and The coating (132) covers the lateral side (135) but does not cover the first side (133).

13. The semiconductor device (100) according to claim 10 or 11, wherein, The first metallic component includes Sn.

14. The semiconductor device (100) according to claim 10 or 11, wherein, The second metal component includes one or more of NiSn, CuSn, ZnSn, SbSn, BiSn, AgSn, CoSn, SiSn, CuNiSn, or CuPdSn.

15. The semiconductor device (100) according to claim 10 or 11, wherein, The semiconductor device further includes: Metal pillars (310) are arranged on a semiconductor die (110), wherein a first welding joint (130) is arranged on the metal pillars (310).

Images