Semiconductor device

Abstract

This semiconductor device comprises: a substrate (2); a semiconductor chip (3) mounted on one surface (2a) of the substrate; and a double ribbon wire (5) including a first ribbon wire (6) having a thickness equal to or less than a prescribed thickness, and a second ribbon wire (7) having a thickness equal to or greater than the prescribed thickness and greater than the thickness of the first ribbon wire, and bonded to the first ribbon wire. The first ribbon wire is bonded to the substrate and the semiconductor chip. A portion of the second ribbon wire is bonded to the first ribbon wire, and the remaining portion is not bonded to another member. Furthermore, the semiconductor device may comprise, instead of the double ribbon wire, a single ribbon wire having a thickness equal to or greater than a prescribed thickness. Given the direction of said single ribbon wire in which the substrate and the semiconductor chip are connected as a loop direction, the single ribbon wire includes a groove-like recessed portion (84) provided along the loop direction and a protruding portion (83) adjacent to the recessed portion, or a bottomed hole (85) or through hole (86) in an area bonded to the semiconductor chip.

Description

Semiconductor device Cross-reference to related applications

[0001] This application is based on Japanese Patent Application No. 2025-13065 filed on January 29, 2025, the contents of which are incorporated herein by reference.

[0002] This disclosure relates to a semiconductor device to which a ribbon wire is joined.

[0003] Conventionally, a semiconductor device including a semiconductor chip, a substrate on which the semiconductor chip is mounted, and a ribbon wire that is joined to the semiconductor chip and the substrate by ultrasonic waves and electrically connects them, and a bonding device that joins the ribbon wire by ultrasonic waves are known (for example, Patent Document 1).

[0004] Japanese Unexamined Patent Application Publication No. 2024-4896

[0005] The semiconductor device described in Patent Document 1 has a structure in which a ribbon wire is joined to a semiconductor chip by ultrasonic waves. When the semiconductor chip is a power semiconductor device such as a power MOSFET or IGBT, a ribbon wire having a thickness of a predetermined value or more needs to be used. MOSFET and IGBT are abbreviations for Metal-Oxide-Semiconductor Field Effect Transistor and Insulated Gate Bipolar Transistor, respectively. When such a ribbon wire having a thickness of a predetermined value or more is ultrasonically joined to a semiconductor chip, the power in ultrasonic bonding must be increased, but damage may occur to the semiconductor chip in ultrasonic bonding. Therefore, as a method for suppressing such damage to the semiconductor chip, for example, a buffer material, a copper foil, etc. are pre-solder-joined to the semiconductor chip, and a ribbon wire is ultrasonically joined thereon, or a clip is solder-joined to the semiconductor chip instead of the ribbon wire. However, these methods require separately solder-joining a member different from the ribbon wire or performing alignment and solder-joining between the clip and the semiconductor chip, resulting in a complicated manufacturing process.

[0006] In view of the above, this disclosure aims to provide a semiconductor device that has a structure in which a ribbon wire of a predetermined thickness or greater is ultrasonically bonded to a semiconductor chip, while suppressing damage to the semiconductor chip and being obtainable through a simple manufacturing process.

[0007] According to one aspect of this disclosure, a semiconductor device comprises a substrate, a semiconductor chip mounted on one surface of the substrate, and a double ribbon wire comprising a first ribbon wire having a thickness of a predetermined or less, and a second ribbon wire having a thickness greater than or equal to a predetermined, and greater than the thickness of the first ribbon wire, and joined to the first ribbon wire, wherein the first ribbon wire is joined to the substrate and the semiconductor chip, and a portion of the second ribbon wire is joined to the first ribbon wire, with the remaining portion not joined to any other component.

[0008] This results in a semiconductor device in which a double ribbon wire, consisting of a first ribbon wire with a predetermined thickness or less and a second ribbon wire with a predetermined or greater thickness, is bonded to the semiconductor chip, thereby suppressing damage to the semiconductor chip caused by ultrasonic bonding of the first ribbon wire. Furthermore, because the second ribbon wire, which is thicker than the first ribbon wire, is bonded to the first ribbon wire, the first ribbon wire plays a role in protecting the semiconductor chip during the ultrasonic bonding of the second ribbon wire, thereby suppressing damage to the semiconductor chip. Moreover, since both the first and second ribbon wires are bonded by ultrasonic bonding, no other process is required to protect the semiconductor chip. Therefore, this semiconductor device has a structure in which a ribbon wire with a predetermined or greater thickness is ultrasonically bonded to the semiconductor chip, suppressing damage to the semiconductor chip while being able to be manufactured with a simple manufacturing process.

[0009] In another aspect of this disclosure, a semiconductor device comprises a substrate, a semiconductor chip mounted on one surface of the substrate, and a ribbon wire having a predetermined or greater thickness bonded to the substrate and the semiconductor chip, wherein the direction in which the ribbon wire connects the substrate and the semiconductor chip is defined as the loop direction, and the ribbon wire has groove-shaped recesses and protrusions adjacent to the recesses provided along the loop direction.

[0010] As a result, a single ribbon wire of a predetermined thickness or greater is bonded to the semiconductor chip, and the ribbon wire has groove-shaped recesses along the loop direction connecting the substrate and the semiconductor chip, as well as protrusions adjacent to the recesses, resulting in a semiconductor device. Because the ribbon wire has recesses and protrusions along the loop direction, the area of ​​the bonding portion between the ribbon wire and the semiconductor chip is reduced, requiring less power for ultrasonic bonding and suppressing damage to the semiconductor chip. Furthermore, since the ribbon wire is bonded by ultrasonic bonding at a power below a predetermined level, no other processes for protecting the semiconductor chip are necessary. Therefore, a semiconductor device has a structure in which a ribbon wire of a predetermined thickness or greater is ultrasonically bonded to a semiconductor chip, suppressing damage to the semiconductor chip, and can be manufactured using a simple manufacturing process.

[0011] In another aspect of this disclosure, a semiconductor device comprises a substrate, a semiconductor chip mounted on one surface of the substrate, and a ribbon wire having a predetermined or greater thickness bonded to the substrate and the semiconductor chip, wherein the ribbon wire has a bottomed hole or a through hole at the bonding portion with the semiconductor chip.

[0012] This results in a semiconductor device in which a single ribbon wire of a predetermined thickness or greater is bonded to a semiconductor chip, and the bonded portion of the ribbon wire has a bottomed hole or through-hole. Because the ribbon wire has a bottomed hole or through-hole, the area of ​​the bonded portion between the ribbon wire and the semiconductor chip is reduced, requiring less power for ultrasonic bonding and suppressing damage to the semiconductor chip. Furthermore, since the ribbon wire is bonded by ultrasonic bonding at a power level below a predetermined level, no other processes are required to protect the semiconductor chip. Therefore, the semiconductor device has a structure in which a ribbon wire of a predetermined thickness or greater is ultrasonically bonded to a semiconductor chip, suppressing damage to the semiconductor chip while being able to be manufactured with a simple manufacturing process.

[0013] This is a cross-sectional view showing a semiconductor device of the first embodiment. This is an enlarged plan view showing an enlarged end face of a ribbon wire. This is a diagram corresponding to the view of a double ribbon wire from direction III in Figure 1, and is an explanatory diagram of the widths of the first ribbon wire and the second ribbon wire. This is a diagram showing a bonding apparatus according to the first embodiment. This is a diagram showing an example of the shape of the cutter in the bonding apparatus of Figure 4. This is a diagram showing another example of the shape of the cutter in the bonding apparatus of Figure 4. This is a diagram showing the first bonding step by the bonding apparatus of Figure 4. This is a diagram showing the step following Figure 7A. This is a diagram showing the step following Figure 7B. This is a diagram showing the step following Figure 7C. This is a diagram showing the step following Figure 7D. This is a diagram showing the step following Figure 7E. This is a cross-sectional view showing a semiconductor device of the second embodiment. This is a plan view showing the ribbon wire of Figure 8 as seen from the bottom. This is a cross-sectional view of the line X-X in Figure 9. This is a cross-sectional view showing a semiconductor device of the third embodiment. This is a plan view showing the ribbon wire in the third embodiment as seen from the bottom. This is a cross-sectional view showing a semiconductor device of the fourth embodiment. This is a plan view showing the ribbon wire in the fourth embodiment as seen from the bottom.

[0014] The embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals. Furthermore, if only a part of a component is described in an embodiment, the other parts of the component can be replaced with components described in a previous embodiment. The following embodiments can be partially combined with each other, even if not explicitly stated, as long as it does not hinder the combination.

[0015] (First Embodiment) The semiconductor device 1 of the first embodiment will be described below.

[0016] [Basic Configuration] The semiconductor device 1 of this embodiment, as shown in Figure 1 for example, comprises a substrate 2, a semiconductor chip 3, a bonding material 4, and a double ribbon wire 5 consisting of a first ribbon wire 6 and a second ribbon wire 7. The semiconductor device 1 has a structure in which, for example, an electrode 21 provided on one surface 2a of the substrate 2 and an electrode 31 of the semiconductor chip 3 are electrically connected by the double ribbon wire 5. The semiconductor device 1 is preferably used for automotive applications, such as being mounted on a vehicle such as an automobile, but of course, it can also be used for other applications.

[0017] The substrate 2 is a plate-shaped member on which the semiconductor chip 3 is mounted, and for example, a printed circuit board or a lead frame can be used. In the case of a printed circuit board, the substrate 2 has a configuration having an insulating plate made of ceramic or the like and a conductive layer made of copper or the like in a patterned shape formed on the insulating plate, for example, an insulating heat dissipation circuit board such as an AMB substrate or a DCB substrate. AMB and DCB are abbreviations for Active Metal Brazing and Direct Copper Bonding, respectively. In the case of a lead frame, for example, the substrate 2 is made of copper or the like and has a configuration having a base portion on which the semiconductor chip 3 is mounted and a terminal portion to which the double ribbon wire 5 is connected, and a plating layer is formed on the surface as needed. The substrate 2 has, for example, an electrode 21 made of a plating layer of copper (Cu), silver (Ag), or gold (Au) on one surface 2a, and the first ribbon wire 6 is bonded to the electrode 21.

[0018] The semiconductor chip 3 is composed of known semiconductor materials such as silicon (Si), silicon carbide (SiC), and gallium nitride (GaN). The semiconductor chip 3 is a power semiconductor element, such as a power MOSFET or IGBT, and is manufactured by a known semiconductor process. The semiconductor chip 3 is mounted on the substrate 2 via a bonding material 4, such as solder. The semiconductor chip 3 has an electrode 31 on the side opposite to the substrate 2, a plating layer 32 covering the electrode 31, and an insulating layer 33 that covers the outer casing of the electrode 31 and has an opening that exposes the plating layer 32 to the outside. The electrode 31 is composed of a single layer film of aluminum (Al) or copper, or a multilayer film such as Al / Cu / Al from the substrate side. The plating layer 32 is composed of copper, nickel (Ni), palladium (Pd), or gold, and is a single layer film or a multilayer film such as Ni / Pd / Au or Ni / Au from the electrode 31 side. The insulating layer 33 is made of an insulating material such as polyimide and has a predetermined pattern shape with openings that expose the plating layer 32 by photolithography etching or the like. One end of the first ribbon wire 6 is joined to the plating layer 32 of the semiconductor chip 3.

[0019] The double ribbon wire 5 is composed of two types of ribbon wires with different thicknesses. The double ribbon wire 5 consists of a first ribbon wire 6 with a thickness of a predetermined or less and a second ribbon wire 7 that is thicker than the first ribbon wire 6 and has a thickness of a predetermined or greater. In the double ribbon wire 5, for example, with the direction in which the ribbon wire connects the substrate 2 and the semiconductor chip 3 as the loop direction, the first ribbon wire 6 and the second ribbon wire 7 are joined at both ends in the loop direction, while the first ribbon wire 6 and the second ribbon wire 7 are separated and not joined at other points.

[0020] The first ribbon wire 6 is, for example, a copper plate material, with a thickness of less than 0.2 mm, more preferably about 0.05 mm to 0.1 mm, and a width of about 1 mm to 3 mm, but is not limited to these. The first ribbon wire 6 is ultrasonically bonded to the substrate 2 and the semiconductor chip 3, respectively, by a bonding apparatus 100, which will be described later. The first ribbon wire 6 has a thickness below a predetermined level so that ultrasonic bonding can be performed with low power so as not to damage the semiconductor chip 3. For example, one end 61 of the first ribbon wire 6 in the loop direction is bonded to the semiconductor chip 3, and the other end 62 in the same direction is bonded to the electrode 21 of the substrate 2. For example, after one end 61 of the first ribbon wire 6 is ultrasonically bonded to the semiconductor chip 3, the other end 62 is ultrasonically bonded to the substrate 2 and cut while still stretched by the bonding apparatus 100, thereby forming a predetermined loop shape.

[0021] Here, the direction normal to one surface 2a of the substrate 2 is defined as the height direction, and the distance in the height direction between the part of the ribbon wire furthest from one surface 2a and one surface 2a is defined as the loop height. In this case, as shown in Figure 1, for example, the loop height h1 of the first ribbon wire 6 is smaller than the loop height h2 of the second ribbon wire 7 by more than the thickness of the second ribbon wire 7. As a result, when ultrasonic bonding of the second ribbon wire 7 to the first ribbon wire 6 is performed, the loop shape of the first ribbon wire 6 is maintained without being distorted.

[0022] Furthermore, as shown in Figure 2, for example, the first ribbon wire 6 has a configuration in which the end face 611 of one end 61 and the end face 621 of the other end 62 have cut surfaces 611a, 621a and fracture surfaces 611b, 621b. This is done by the bonding apparatus 100, and the end face 711 of one end 71 and the end face 721 of the other end 72 of the second ribbon wire 7 have a similar configuration.

[0023] Furthermore, the first ribbon wire 6 may have the same width as the second ribbon wire 7, but it is more preferable that it be narrower than the second ribbon wire 7, as shown in Figure 3, for example. This is because reducing the bonding area between the first ribbon wire 6 and the semiconductor chip 3 further reduces the power used in ultrasonic bonding, thereby further suppressing damage to the semiconductor chip 3. In Figure 3, the side of the ribbon wires 6 and 7 facing the substrate 2 is considered the bottom surface, and the opposite side is considered the top surface, showing the view from the top side. The outline of the first ribbon wire 6, which is hidden by the second ribbon wire 7, is shown with a dashed line.

[0024] The second ribbon wire 7 is, for example, a copper plate material with a thickness of about 0.2 mm to 0.3 mm and a width of about 1 mm to 3 mm, but is not limited to these. The second ribbon wire 7 is at least thicker than the first ribbon wire 6 and has a thickness greater than a predetermined amount so that a large current can be carried when driving the semiconductor chip 3. The second ribbon wire 7 is ultrasonically bonded to the first ribbon wire 6 after the first ribbon wire 6 has been bonded to the substrate 2 and the semiconductor chip 3, and is not directly bonded to the semiconductor chip 3. The second ribbon wire 7 is ultrasonically bonded, for example, by a bonding apparatus 100, with one end 71 in the loop direction to one end 61 of the first ribbon wire 6 and the other end 72 in the same direction to the other end 62 of the first ribbon wire 6. At this time, the second ribbon wire 7 is ultrasonically bonded with a higher power than when the first ribbon wire 6 is ultrasonically bonded, but since one end 61 of the first ribbon wire 6 functions as a protective film for the semiconductor chip 3, damage to the semiconductor chip 3 due to the ultrasonic bonding of the second ribbon wire 7 is suppressed.

[0025] The above describes the basic configuration of the semiconductor device 1 of this embodiment. The semiconductor device 1 only needs to have a bonding structure comprising a substrate 2, a semiconductor chip 3 mounted on the substrate 2, and a double ribbon wire 5 bonded to the semiconductor chip 3, but it may include other components, and the configuration of parts other than the bonding structure can be changed as appropriate.

[0026] [Bonding apparatus] Next, the bonding apparatus 100 will be described.

[0027] The bonding apparatus 100 includes a head 140 having a guide 110, a cutter 120, and a bonding tool 130, as shown in Figure 4, for example, with the cutter 120 positioned between the guide 110 and the bonding tool 130. For the sake of explanation, the direction in which the head 140 moves without moving away from the object 200 to be ultrasonically bonded will be referred to as "forward," and the opposite direction will be referred to as "backward." Furthermore, the direction in which the head 140 moves away from the object 200 along the direction perpendicular to forward and backward will be referred to as "upward," the opposite direction will be referred to as "downward," and the forward, backward, upward, and downward directions will be collectively referred to as "upward, backward, and forward." The directions of the arrows shown in Figure 4 correspond to the aforementioned upward, backward, and forward and backward directions. This is also true for Figures 7A to 7F, which will be described later.

[0028] The guide 110 houses the strip-shaped metal members 150 that will become the ribbon wires 6 and 7, and has an opening at its tip from which the metal members 150 are continuously supplied. The strip-shaped metal members 150 are made of, for example, copper. The guide 110 sequentially supplies the metal members 150 from the opening at its tip, and while stretching the metal members 150, moves relative to the object to be joined 200 (for example, a substrate 2 or a semiconductor chip 3) in an up-down, back-and-forth, and so forth motion with the head 140, thereby forming a loop shape for the ribbon wire.

[0029] The cutter 120 cuts the metal member 150 supplied from the guide 110. The cutter 120 is positioned in front of the bonding tool 130, with the direction in which the guide 110 moves relative to the substrate 2 or semiconductor chip 3 being forward and the opposite direction being backward. In conventional bonding apparatuses where the cutter is positioned behind the bonding tool, there is a risk that the cutter may interfere with the loop shape of the ribbon wire after ultrasonic bonding, which can alter the loop shape of the ribbon wire and prevent the formation of minute loop shapes. In contrast, in the bonding apparatus 100, the cutter 120 is positioned in front of the bonding tool 130. As a result, the cutter 120 is positioned at a distance from the metal member 150 after ultrasonic bonding, which suppresses interference between the loop shape formed on the metal member 150 and the cutter 120, and allows the loop shape to be maintained as is.

[0030] The cutter 120 has a shape or blade width that partially cuts the metal member 150 joined to the substrate 2 or semiconductor chip 3 by the joining tool 130. The cutter 120 can be, for example, a grooved blade as shown in Figure 5, or a narrow blade with a width W1 that is narrower than the width W2 of the metal member 150 that will become the ribbon wires 6 and 7, as shown in Figure 6. Note that Figures 5 and 6 show the cutter 120 viewed from the V direction in Figure 4, and elements other than the cutter 120 and the metal member 150 are omitted. For example, in the case of a grooved blade, the cutter 120 has an overall width greater than or equal to the width of the metal member 150, and the width of the grooved portion, i.e., the blade portion, is less than the width of the metal member 150. For example, in the case of a narrow blade, the cutter 120 has a width that is about 0.1 mm to 1 mm narrower than the metal member 150 and has a flat shape without grooves. In other words, the bonding apparatus 100, after half-cutting the metal member 150 with the cutter 120, moves the guide 110 forward, upward, or both to tear off the uncut portion of the metal member 150, thereby forming a ribbon. This makes it possible to secure the remaining portion of the ribbon that protrudes from the opening of the guide 110 and is used for the next ultrasonic bonding.

[0031] Furthermore, the cutter 120 only needs to have a shape or blade width that allows it to partially cut the metal member 150 in the width direction, for example, more than half, and then tear it off by moving the guide 110. It is not limited to the above-mentioned uneven blade or narrow blade, and may be modified as appropriate.

[0032] The joining tool 130 presses the metal member 150 toward the object to be joined, such as the substrate 2 or semiconductor chip 3, with its tip, and joins the metal member 150 and the object to be joined by applying ultrasonic waves. The joining tool 130, together with the cutter 120, is located near the guide 110 and is positioned so as to conceal the cutter 120 from the metal member 150 after joining.

[0033] The above describes the basic configuration of the bonding apparatus 100. The bonding apparatus 100 performs bonding of the metal member 150 in the process described below, thereby suppressing interference between the cutter 120 and the ribbon wire while also securing the remaining portion of the ribbon.

[0034] For example, as shown in Figure 7A, the bonding apparatus 100 lowers the bonding tool 130 onto the metal member 150, and applies ultrasonic waves at a predetermined power while pressing the metal member 150 against the first workpiece 200 (e.g., substrate 2) with the bonding tool 130 to perform the first bonding. Subsequently, as shown in Figure 7B, for example, the bonding apparatus 100 forms a loop shape of the ribbon wire by moving the head 140 in the up, down, forward, and backward directions while stretching the metal member 150. Then, as shown in Figure 7C, for example, the bonding apparatus 100 performs ultrasonic bonding of the metal member 150 to the second workpiece 210 (e.g., semiconductor chip 3) in the same manner as the first bonding. After that, as shown in Figure 7D, for example, the bonding apparatus 100 strokes the cutter 120 to perform a half-cut of the metal member 150. Then, as shown in Figure 7E, for example, the bonding apparatus 100 moves the head 140 forward, supplies the metal member 150 from the guide 110, and feeds out the remaining portion of the ribbon. Finally, as shown in Figure 7F, for example, the bonding apparatus 100 clamps the ribbon wire and moves the head 140 upward and forward to tear off the remaining portion of the metal member 150 that was not cut by the half-cut. This forms a ribbon wire with a predetermined loop shape, and because the cutter 120 does not interfere with the ribbon wire, it is possible to create a ribbon wire with a very small shape.

[0035] Furthermore, the formed ribbon wire, after undergoing the half-cutting and subsequent tearing processes described above, will have a shape in which both end faces in the loop direction have a cut surface made by the cutter 120 and a fracture surface made by the tearing process, but this does not pose any particular problem. In addition, when a double ribbon wire 5 is formed by the bonding device 100, interference between the cutter 120 and the ribbon wires 6 and 7 is suppressed, so the ribbon wires 6 and 7 are maintained as they are, even in the form of a minute loop shape.

[0036] According to this embodiment, the semiconductor device 1 is formed by bonding a double ribbon wire 5, consisting of a first ribbon wire 6 with a predetermined thickness or less and a second ribbon wire 7 with a predetermined thickness or greater, to a semiconductor chip 3. Since the thickness of the first ribbon wire 6, which is directly ultrasonically bonded to the semiconductor chip 3, is predetermined or less, the power used in ultrasonic bonding can be reduced, and damage to the semiconductor chip 3 is suppressed. Because the thicker second ribbon wire 7 is bonded to the first ribbon wire 6, the semiconductor chip 3 is protected by the first ribbon wire 6, suppressing damage to the semiconductor chip 3, and also allowing for cases where the semiconductor chip 3 is a power semiconductor element. Furthermore, although both ribbon wires 6 and 7 are bonded by ultrasonic bonding, no protection process for the semiconductor chip 3 is required. As a result, the semiconductor device 1 has a structure in which a double ribbon wire 5 with a predetermined thickness or greater is ultrasonically bonded to the semiconductor chip 3 while suppressing damage to the semiconductor chip 3, and can be manufactured using a simple manufacturing process. The semiconductor device 1 of this embodiment also has the following features.

[0037] (1) The first ribbon wire 6 is narrower than the second ribbon wire 7. This reduces the bonding area between the first ribbon wire 6 and the semiconductor chip 3, allowing ultrasonic bonding to be performed at a lower power, and further suppressing damage to the semiconductor chip 3.

[0038] (2) The loop height of the first ribbon wire 6 is smaller than that of the second ribbon wire 7 by more than the thickness of the second ribbon wire 7. As a result, the loop shape of the second ribbon wire 7 is formed without the loop shape of the first ribbon wire 6 being distorted.

[0039] (3) The first ribbon wire 6 and the second ribbon wire 7 have end faces 611, 621, 711, and fracture surfaces at one end 61, 71 and the other end 62, 72, which are the ends in the loop direction.

[0040] (Second Embodiment) The semiconductor device 1 of the second embodiment will now be described. The semiconductor device 1 of this embodiment differs from the first embodiment in that, as shown in Figure 8, for example, a single ribbon wire 8 is joined instead of a double ribbon wire 5. This embodiment will mainly describe this difference. In Figure 8, a part of the outer edge of another cross-section of the ribbon wire 8 is shown with a dashed line.

[0041] The ribbon wire 8 has one end 81 in the loop direction bonded to the semiconductor chip 3, and the other end 82 in the same direction bonded to the electrode 21 of the substrate 2. For example, in this embodiment, as shown in Figures 9 and 10, the ribbon wire 8 has a plurality of protrusions 83 and groove-shaped recesses 84 along the loop direction, and the protrusions 83 are bonded to the electrode 21 of the substrate 2 and the semiconductor chip 3. In Figure 9, the ribbon wire 8 is shown as viewed from the bottom side, with the substrate side being the bottom surface. The ribbon wire 8 is easily deformable due to the presence of the recesses 84, and the bonding area with the semiconductor chip 3 is reduced due to the presence of the protrusions 83, making it possible to bond with reduced power in ultrasonic bonding. For example, the thickness of the protrusions 83 of the ribbon wire 8 is about 0.2 mm to 0.3 mm, and the thickness of the recesses 84 is 0.1 mm or less, but it is not limited to this. Also, the number of protrusions 83 and recesses 84 and their arrangement in the width direction of the ribbon wire 8 can be changed as appropriate.

[0042] When the ribbon wire 8 is bonded by the bonding device 100, the end face 811 of one end 81 and the end face 821 of the other end 82 will have a shape that includes a cut surface and a fracture surface. This is also the case in the third and fourth embodiments described later.

[0043] This embodiment also provides a semiconductor device 1 that offers the same effects as the first embodiment described above.

[0044] (Third Embodiment) The semiconductor device 1 of the third embodiment will be described. The semiconductor device 1 of this embodiment differs from the first embodiment in that, as shown in Figure 11, for example, a single ribbon wire 8 is joined instead of a double ribbon wire 5, and the ribbon wire 8 has a bottomed hole 85 at the joint portion with the semiconductor chip 3. This embodiment will mainly describe this difference.

[0045] As shown in, for example, FIG. 12, the ribbon wire 8 has a bottomed hole 85 with a substantially cylindrical shape formed at one end 81 which is a joint portion with the semiconductor chip 3. The bottomed hole 85 is provided to reduce the joint area between the one end 81 and the semiconductor chip 3 and to enable joining with a reduced power in ultrasonic joining. The bottomed hole 85 only needs to be able to reduce the joint area between the one end 81 and the semiconductor chip 3, and its shape, depth, and diameter can be appropriately changed. Also, not only one bottomed hole 85 but a plurality of them may be provided, or they may be provided at locations other than the one end 81 of the ribbon wire 8.

[0046] Also, according to the present embodiment, the semiconductor device 1 that can obtain the same effects as those of the first embodiment is obtained.

[0047] (Fourth Embodiment) The semiconductor device 1 of the fourth embodiment will be described. As shown in, for example, FIG. 13, the semiconductor device 1 of the present embodiment is different from the first embodiment in that one ribbon wire 8 is joined instead of the double ribbon wires 5, and the ribbon wire 8 has a through hole 86 at the joint portion with the semiconductor chip 3. In the present embodiment, this difference will be mainly described.

[0048] As shown in, for example, FIG. 14, the ribbon wire 8 has a through hole 86 with a substantially cylindrical shape formed at one end 81 which is a joint portion with the semiconductor chip 3. The through hole 86 serves the same role as the bottomed hole 85 of the third embodiment. The through hole 86 only needs to be able to reduce the joint area between the one end 81 and the semiconductor chip 3, and its shape, diameter, number, arrangement, etc. can be appropriately changed. Also, the through hole 86 may be provided at locations other than the one end 81 of the ribbon wire 8 as necessary.

[0049] Also, according to the present embodiment, the semiconductor device 1 that can obtain the same effects as those of the first embodiment is obtained.

[0050] (Other Embodiments) While this disclosure has been described in accordance with the embodiments, it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also encompasses a variety of modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms including one, more, or less of those elements, fall within the scope and concept of this disclosure.

[0051] It goes without saying that, in each of the above embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated to be particularly essential or unless they are clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated to be particularly essential or unless it is clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shape, positional relationship, etc., of the components are mentioned, the embodiment is not limited to those shapes, positional relationships, etc., unless explicitly stated or unless it is clearly limited to a specific shape, positional relationship, etc., in principle.

[0052] (Perspectives of this Disclosure) As will be apparent from the description of the embodiments above, the disclosures herein include at least the following perspectives:

[0053] (Problem) The semiconductor device described in Patent Document 1 has a structure in which a ribbon wire is bonded to a semiconductor chip by ultrasound. When the semiconductor chip is a power semiconductor element such as a power MOSFET or IGBT, it is necessary to use a ribbon wire of a certain thickness or greater. When ultrasonically bonding such a ribbon wire of a certain thickness or greater to a semiconductor chip, the power of the ultrasonic bonding must be increased, but damage to the semiconductor chip may occur during ultrasonic bonding. As a method to suppress such damage to the semiconductor chip, for example, a buffer material or copper foil is soldered to the semiconductor chip in advance and the ribbon wire is ultrasonically bonded on top of it, or a clip is soldered to the semiconductor chip instead of the ribbon wire. However, these methods require soldering a component other than the ribbon wire separately, or aligning and soldering the clip to the semiconductor chip, which complicates the manufacturing process. In view of the above points, this disclosure aims to provide a semiconductor device that has a structure in which a ribbon wire of a certain thickness or greater is ultrasonically bonded to a semiconductor chip, while suppressing damage to the semiconductor chip and being obtainable through a simple manufacturing process.

[0054] [Perspective 1-1] A semiconductor device comprising: a substrate (2); a semiconductor chip (3) mounted on one surface (2a) of the substrate; and a double ribbon wire (4) comprising a first ribbon wire (6) having a thickness of a predetermined or less, and a second ribbon wire (7) having a thickness of a predetermined or greater and greater than the first ribbon wire, and joined to the first ribbon wire, wherein the first ribbon wire is joined to the substrate and the semiconductor chip, and a portion of the second ribbon wire is joined to the first ribbon wire, with the remaining portion not joined to any other component. [Perspective 1-2] The semiconductor device according to Perspective 1-1, wherein the first ribbon wire is narrower than the second ribbon wire. [Viewpoint 1-3] The semiconductor device according to Viewpoint 1-1 or 1-2, wherein the direction along the normal direction to the surface is defined as the height direction, and the distance in the height direction between the first ribbon wire and the surface and the point of the first ribbon wire furthest from the surface is defined as the loop height, and the loop height of the first ribbon wire is less than or equal to the thickness of the second ribbon wire. [Viewpoint 1-4] The semiconductor device according to any one of Viewpoints 1-1 to 1-3, wherein the direction in which the double ribbon wire connects the substrate and the semiconductor chip is defined as the loop direction, and the end faces (611, 621, 711, 721) of the ends (61, 62, 71, 72) in the loop direction of the first ribbon wire and the second ribbon wire have a cut surface and a fracture surface. [Perspective 1-5] A semiconductor device comprising: a substrate (2); a semiconductor chip (3) mounted on one surface (2a) of the substrate; and a ribbon wire (8) of a predetermined or greater thickness bonded to the substrate and the semiconductor chip, wherein the ribbon wire has a groove-shaped recess (84) and a protrusion (83) adjacent to the recess, with the direction in which the ribbon wire connects the substrate and the semiconductor chip being the loop direction. [Perspective 1-6] A semiconductor device comprising: a substrate (2); a semiconductor chip (3) mounted on one surface (2a) of the substrate; and a ribbon wire (8) of a predetermined or greater thickness bonded to the substrate and the semiconductor chip, wherein the ribbon wire has a bottomed hole (85) or a through hole (86) at the bonding portion with the semiconductor chip.[Perspective 1-7] The semiconductor device according to Perspective 1-6, wherein the direction in which the ribbon wire connects the substrate and the semiconductor chip is defined as the loop direction, and the cross-section of the end of the ribbon wire in the loop direction has a cut surface and a fracture surface.

[0055] (Problem) The bonding apparatus described in Patent Document 1 comprises a guide capable of supplying ribbon wire, a bonding tool capable of pressing the ribbon wire supplied from the guide and bonding it by applying ultrasonic waves, and a cutter capable of cutting the ribbon wire, with the cutter positioned behind the bonding tool. In this bonding apparatus, when attempting to form a minute shape with the ribbon wire, the formed ribbon wire and the cutter interfere with each other, causing the ribbon wire to deform, making it difficult to form a minute shape with the ribbon wire. To suppress such interference between the cutter and the ribbon wire and the resulting deformation, it is conceivable to have a bonding apparatus configured with the cutter positioned in front of the bonding tool. However, in this case, when the ribbon wire is cut with the cutter, the remaining portion of the ribbon wire that was pulled out from the guide, i.e., the remaining portion, is lost, making it impossible to secure the remaining portion to be used in the next bonding. The object of this disclosure is to provide a bonding apparatus that can secure the remaining portion of the ribbon wire after cutting while suppressing interference between the bonded ribbon wire and the cutter.

[0056] [Perspective 2-1] A bonding apparatus for joining ribbon wires (6, 7, 8) by ultrasonic waves, comprising: a guide (110) capable of supplying the ribbon wires; a cutter (120) capable of cutting the ribbon wires; and a bonding tool (130) positioned adjacent to the guide, capable of pressing the ribbon wires supplied from the guide and applying ultrasonic waves, wherein, in bonding the ribbon wires, the direction in which the guide advances is considered forward and the opposite direction is considered backward, the cutter is positioned in front of the bonding tool and has a grooved blade for partially cutting the ribbon wires. [Perspective 2-2] A bonding apparatus for joining ribbon wires (6, 7, 8) by ultrasonic waves, comprising: a guide (110) capable of supplying the ribbon wires; a cutter (120) capable of cutting the ribbon wires; and a bonding tool (130) positioned adjacent to the guide, capable of pressing the ribbon wires supplied from the guide and applying ultrasonic waves, wherein, in bonding the ribbon wires, the direction in which the guide advances is considered forward and the opposite direction is considered backward, the cutter is positioned in front of the bonding tool, and has a narrow blade that is narrower than the width of the ribbon wire and partially cuts the ribbon.

Claims

1. A semiconductor device comprising: a substrate (2); a semiconductor chip (3) mounted on one surface (2a) of the substrate; and a double ribbon wire (5) comprising a first ribbon wire (6) having a thickness of a predetermined or less, and a second ribbon wire (7) having a thickness greater than or equal to a predetermined, and being thicker than the first ribbon wire and joined to the first ribbon wire, wherein the first ribbon wire is joined to the substrate and the semiconductor chip, and a portion of the second ribbon wire is joined to the first ribbon wire, with the remaining portion not joined to any other component.

2. The semiconductor device according to claim 1, wherein the first ribbon wire is narrower in width than the second ribbon wire.

3. The semiconductor device according to claim 1 or 2, wherein the direction along the normal direction to the surface is defined as the height direction, and the distance in the height direction between the first ribbon wire and the surface and the point of the first ribbon wire furthest from the surface is defined as the loop height, and the loop height of the first ribbon wire is smaller than or equal to the thickness of the second ribbon wire.

4. The semiconductor device according to claim 1 or 2, wherein the direction in which the double ribbon wires connect the substrate and the semiconductor chip is defined as the loop direction, and the end faces (611, 621, 711, 721) of the ends (61, 62, 71, 72) in the loop direction of the first ribbon wire and the second ribbon wire have a cut surface and a fracture surface.

5. A semiconductor device comprising: a substrate (2); a semiconductor chip (3) mounted on one surface (2a) of the substrate; and a ribbon wire (8) having a predetermined or greater thickness bonded to the substrate and the semiconductor chip, wherein the ribbon wire has a groove-shaped recess (84) and a protrusion (83) adjacent to the recess, with the direction in which the ribbon wire connects the substrate and the semiconductor chip being the loop direction.

6. A semiconductor device comprising: a substrate (2); a semiconductor chip (3) mounted on one surface (2a) of the substrate; and a ribbon wire (8) having a predetermined or greater thickness bonded to the substrate and the semiconductor chip, wherein the ribbon wire has a bottomed hole (85) or a through hole (86) at the bonding portion with the semiconductor chip.

7. The semiconductor device according to claim 6, wherein the direction in which the ribbon wire connects the substrate and the semiconductor chip is defined as the loop direction, and the end faces (811, 821) of the ends (81, 82) in the loop direction have a cut surface and a fracture surface.

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