Semiconductor device and method for manufacturing semiconductor device

Abstract

According to one embodiment, a semiconductor device includes: an insulating substrate having a circuit pattern; a semiconductor chip fixed on the insulating substrate and electrically connected to the circuit pattern; and a power supply terminal that includes a metal of the same type as the circuit pattern and is electrically connected to the circuit pattern, the power supply terminal having: a flat plate-shaped bonding portion that is bonded to the circuit pattern; a penetrating portion penetrating the joining portion in the thickness direction of the joining portion; and an extension part which is bent from one end of the bonding part and extends upward, and is configured so as to be able to connect the circuit pattern and an external device, the bonding part and the circuit pattern being bonded by a bonding material containing particles of a metal of the same type as the power supply terminal and the circuit pattern.

Description

Technical Field

[0001] Embodiments of the present invention relate to a semiconductor device and a method for manufacturing the semiconductor device. Background Art

[0002] When manufacturing a semiconductor device, a process of bonding external terminals such as power terminals and signal terminals to a circuit pattern of an insulating substrate on which a semiconductor chip is mounted is sometimes performed. For example, ultrasonic bonding is performed while a load is applied to the external terminals and the circuit pattern. In this way, the coating formed on the surface of the circuit pattern and the external terminals based on natural oxidation can be destroyed and they can be electrically bonded.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-259880

[0006] Patent Document 2: International Publication No. 2020 / 245880 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the bonding of the external terminal and the circuit pattern by ultrasonic bonding, the insulating substrate may be damaged by the pressure applied thereto and the vibration of ultrasonic waves.

[0009] An object of one embodiment is to provide a semiconductor device and a method for manufacturing the semiconductor device, which are capable of bonding an external terminal to a circuit pattern of an insulating substrate while suppressing damage.

[0010] Means used to solve problems

[0011] A semiconductor device in an embodiment comprises: an insulating substrate having a circuit pattern; a semiconductor chip fixed on the insulating substrate and electrically connected to the circuit pattern; and a power terminal comprising a metal of the same type as the circuit pattern and electrically connected to the circuit pattern, the power terminal comprising: a flat-plate-shaped joining portion joined to the circuit pattern; a through portion penetrating the joining portion in a thickness direction of the joining portion; and an extension portion bent from one end of the joining portion and extending upward, configured to be able to connect the circuit pattern to an external device, the joining portion and the circuit pattern being joined by a joining material comprising particles of the same metal as the power terminal and the circuit pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram showing an example of the structure of a semiconductor device according to an embodiment.

[0013] Figure 2 It is an enlarged view of a joint portion included in the power terminal according to the embodiment.

[0014] Figure 3 It is an enlarged perspective view of a joint portion included in the signal terminal according to the embodiment.

[0015] Figure 4 It is a cross-sectional view showing an example of the steps of the method for manufacturing the semiconductor device according to the embodiment.

[0016] Figure 5 It is a cross-sectional view showing an example of the steps of the method for manufacturing the semiconductor device according to the embodiment.

[0017] Figure 6 It is a cross-sectional view showing an example of the steps of the method for manufacturing the semiconductor device according to the embodiment.

[0018] Figure 7 It is a cross-sectional view showing an example of the steps of the method for manufacturing the semiconductor device according to the embodiment.

[0019] Figure 8 It is a cross-sectional view showing how the power supply terminal and the circuit pattern are connected in the embodiment and the comparative example.

[0020] Fig. 9 This is an enlarged view of a joint portion included in a power terminal according to Modification 1 of the embodiment.

[0021] Fig.10 It is a plan view of the lower surface side of the joining portion included in the power terminal according to Modification 2 of the embodiment. DETAILED DESCRIPTION

[0022] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In addition, the present invention is not limited to the following embodiments. In addition, the constituent elements in the following embodiments include elements that can be easily conceived by those skilled in the art or substantially the same elements.

[0023] (Configuration Example of Semiconductor Device)

[0024] Figure 1 1 is a cross-sectional view showing an example of the structure of the semiconductor device 1 according to the embodiment. Figure 1 As shown, the semiconductor device 1 according to the embodiment includes a base plate 10 , a circuit board 20 , a semiconductor chip 30 , a package 40 , a power supply terminal 51 , and a signal terminal 52 .

[0025] The base plate 10 is a flat plate-shaped member made of, for example, AlSiC, etc. The base plate 10 functions as a support member for supporting the entire semiconductor device 1 and also functions as a heat sink for dissipating heat generated during operation of the semiconductor chip 30 .

[0026] The circuit board 20 is provided on the base plate 10 . The circuit board 20 includes a flat insulating substrate 21 and circuit patterns 22 a and 22 b provided on both surfaces of the insulating substrate 21 .

[0027] The insulating substrate 21 is a flat plate made of ceramics such as SiN and AlN. The circuit patterns 22a and 22b are made of Cu, for example. The circuit pattern 22a is provided on the lower surface side of the insulating substrate 21 in a manner opposite to the base plate 10, and is connected to the base plate 10 by solder 12. The circuit pattern 22b is provided on the upper surface side of the insulating substrate 21.

[0028] The semiconductor chip 30 is fixed on the lower surface to the circuit pattern 22b of the circuit board 20. The semiconductor chip 30 and the circuit pattern 22b are fixed by a sintering material 32 such as Cu or Ag. The sintering material 32 such as Cu or Ag is obtained by sintering Cu paste or Ag paste.

[0029] The semiconductor chip 30 is, for example, a metal oxide semiconductor field effect transistor (MOSFET), and the material is SiC. When the semiconductor chip 30 is a MOSFET, it has a gate pad as a gate electrode, a P electrode as a drain electrode, and an N electrode as a source electrode. That is, the gate electrode and the N electrode as the source electrode are provided on the upper surface of the semiconductor chip 30, and the P electrode as the drain electrode is provided on the lower surface of the semiconductor chip 30 bonded to the circuit pattern 22b.

[0030] The SiC semiconductor chip has high temperature resistance and can operate with high reliability at high temperatures. The sintered material 32 formed by sintering the Cu paste or Ag paste described above is a material that is less degraded even in the high-temperature operating environment of the SiC semiconductor chip 30 .

[0031] In addition, the semiconductor chip 30 on the upper surface of the semiconductor chip 30 is electrically connected to the circuit pattern 22b around the semiconductor chip 30 through a wire 35 made of Al material or the like. Among the wires 35 connecting the semiconductor chip 30 and the circuit pattern 22b, there are gate wires connecting the gate electrode of the semiconductor chip 30 and the circuit pattern 22b, and wires connecting the source electrode, i.e., the N electrode, of the semiconductor chip 30 and the circuit pattern 22b.

[0032] The package 40 includes a rectangular housing 41 surrounding the circuit board 20 and the semiconductor chip 30 on the base plate 10, and a cover 42 that closes the rectangular housing 41. The housing 41 and the cover 42 may be made of, for example, thermoplastic polyphenylene sulfide (PPS: Poly Phenylene Sulfide) resin. The housing 41 is fixed to the base plate 10 by a connecting material 44 such as a silicone resin. The cover 42 is also fixed to the upper end of the housing 41 by a connecting material 44 such as a silicone resin.

[0033] The power terminal 51 and the signal terminal 52 are long strip-shaped parts made of Cu, one end of which is connected to the circuit pattern 22b of the circuit substrate 20 through the Cu sintered material 60, and the other end is bent along the upper surface of the cover 42 of the package 40. These power terminals 51 and signal terminals 52 are preferably made of oxygen-free copper C1020 or the like.

[0034] The power terminal 51 and the signal terminal 52 function as external terminals for connecting the semiconductor chip 30 to an external device of the semiconductor device 1 via the circuit substrate 20. The power terminal 51 includes, for example, a P terminal electrically connected to a P electrode of the semiconductor chip 30, an N terminal electrically connected to an N electrode of the semiconductor chip 30, and an AC terminal (not shown) serving as an output terminal.

[0035] The Cu sintered material 60 as the bonding material is obtained by sintering a non-pressurized Cu paste, for example. That is, as described later, the external terminal and the circuit pattern 22b can be bonded by interposing the non-pressurized Cu paste between the external terminal such as the power terminal 51 and the circuit pattern 22b and heating and sintering.

[0036] Here, the power terminal 51, the signal terminal 52, and the circuit pattern 22b are all mainly composed of, for example, Cu. By using a non-pressurized Cu paste containing a metal having a high affinity with the metal constituting the power terminal 51, the signal terminal 52, and the circuit pattern 22b, the power terminal 51, the signal terminal 52, and the circuit pattern 22b can be firmly bonded. In addition, by using, for example, a non-pressurized Cu paste instead of an Ag paste containing expensive Ag, the manufacturing cost of the semiconductor device 1 can be reduced.

[0037] The non-pressurized Cu paste is a material in which nano-sized Cu particles are diffused in an organic solvent to form a paste. The organic solvent includes, for example, an organic protective agent and a sintering accelerator. The organic solvent is, for example, a carboxylic acid compound. The organic protective agent protects the Cu particles in the non-pressurized Cu paste, disperses the nano-sized Cu particles to achieve homogenization, and inhibits the bonding of the non-pressurized Cu paste at room temperature. The sintering accelerator promotes the sintering of the non-pressurized Cu paste when the non-pressurized Cu paste is heated.

[0038] In addition, even without applying a load, the non-pressurized Cu paste can be sintered by heating at a predetermined temperature and used for bonding with other components. In the non-pressurized Cu paste, an organic protective agent such as an organic protective agent that decomposes at a relatively low temperature is used, which is different from the pressurized Cu paste that is sintered while applying a load, so that bonding without applying pressure can be performed.

[0039] By forming the Cu sintered material 60 from such a non-pressurized Cu paste, Cu particles or traces thereof contained in the non-pressurized Cu paste can be observed in the Cu sintered material 60. In addition, the Cu sintered material 60 may contain voids generated by the organic solvent vaporized during sintering.

[0040] Furthermore, the circuit substrate 20 and the semiconductor chip 30 in the package 40 , including the connection portions between the power terminals 51 and the signal terminals 52 and the circuit substrate 20 , are sealed by a potting material 33 such as silicone gel.

[0041] Next, use Figure 2 and Figure 3 , a more detailed configuration example of the connection portion between the power terminal 51 and the signal terminal 52 and the circuit substrate 20 will be described.

[0042] Figure 2 : is an enlarged view of the joint portion 512 provided in the power terminal 51 of the embodiment. More specifically, Figure 2 (a) is a three-dimensional view of the joint 512, Figure 2 (b) is a top view of the lower surface side of the joint portion 512, Figure 2 (c) is a cross-sectional view of the joint portion 512 as viewed from the side.

[0043] like Figure 2 As shown, the power terminal 51 includes an extension portion 511 and a bonding portion 512. The bonding portion 512 is a flat plate-shaped portion bonded to the circuit pattern 22b. The extension portion 511 is bent from one end of the bonding portion 512 and extends upward, and is configured to electrically connect the circuit pattern 22b to an external device of the semiconductor device 1.

[0044] The joint portion 512 is provided with a through portion 513 that penetrates the joint portion 512 in the thickness direction. Figure 2 In the example of , the through portion 513 has a circular shape. In this case, the shape of the through portion 513 can be a perfect circle at least in design. However, from the perspective of processing accuracy, this does not mean that the final shape of the through portion 513 is also a perfect circle.

[0045] In order to sufficiently maintain the strength of the entire joint 512, it is preferred that a width of a predetermined distance or more be left from the outer edge of the through-portion 513 to each end of the joint 512. As an example, when the thickness of the joint 512 is 1 mm or more and 1.5 mm or less, it is considered that sufficient strength can be ensured as long as a width of 1 mm or more is maintained from the outer edge of the through-portion 513 to each end of the joint 512.

[0046] like Figure 2 As shown in (b), the through portion 513 is provided at the lower surface of the joint portion 512, that is, the center portion of the joint surface of the joint portion 512 with the circuit pattern 22b. That is, the center point of the through portion 513 observed from above is substantially consistent with the center point of the joint surface of the joint portion 512. Here, substantially consistent includes the case where the center point of the through portion 513 is completely consistent with the center point of the joint portion 512, and may also include errors in positional deviation when the through portion 513 is formed.

[0047] Such a through portion 513 can be formed by, for example, wire discharge machining, etc. In wire discharge machining, for example, current is passed through a brass wire to generate discharge between the wire and the joining portion 512 of the object being machined. The joining portion 512 of the object being machined is partially melted and cut by the discharge heat.

[0048] However, the through-hole 513 may be formed by other methods such as electron beam irradiation or laser irradiation.

[0049] The Cu sintered material 60 is interposed between the lower surface of the bonding portion 512 and the upper surface of the circuit pattern 22 b to bond them together.

[0050] In addition, the Cu sintered material 60 is also filled in the through-hole 513 of the joint 512. At this time, it is preferred that the Cu sintered material 60 reaches the height position of the upper end of the through-hole 513, and the upper end of the Cu sintered material 60 may be in a state of slightly protruding from the upper surface of the joint 512. In this way, by filling the through-hole 513 with the Cu sintered material 60, an anchoring effect based on the Cu sintered material 60 can be obtained, and the shear strength of the joint portion between the power terminal 51 and the Cu sintered material 60 is increased, resulting in a highly reliable joint portion.

[0051] In addition, at this time, the permissible thickness of the Cu sintered material 60 in the through-portion 513 is preferably such that the organic solvent in the non-pressurized Cu paste is not hindered from escaping when the non-pressurized Cu paste is sintered. As an example, the height from the bonding interface between the circuit pattern 22b and the Cu sintered material 60 to the upper end of the Cu sintered material 60 protruding from the through-portion 513 is less than 1.5 times the thickness of the bonding portion 512 itself. In other words, the protruding height of the Cu sintered material 60 from the through-portion 513 is less than half the thickness of the bonding portion 512.

[0052] However, as a state that satisfies both the improvement of shear strength brought by the Cu sintered material 60 and the separation of the organic solvent during sintering, it is more preferable that the upper surface of the Cu sintered material 60 in the through-portion 513 is substantially at the same height as the upper surface of the joint 512. The substantially equal height position includes the case where the heights of the upper surfaces of the Cu sintered material 60 and the upper surfaces of the joint 512 are completely equal, and may also include the error in the filling amount when the Cu sintered material 60 is filled.

[0053] In addition, the Cu sintered material 60 has a curled shape and covers the side of the joint 512. That is, the Cu sintered material 60 has a tapered shape extending from the upper surface of the joint 512 toward the circuit pattern 22b of the circuit substrate 20 on the side of the joint 512. However, the tapered portion of the Cu sintered material 60 may be bent between the upper surface of the joint 512 and the circuit pattern 22b. That is, the inclined surface of the Cu sintered material 60 of the tapered portion may also be a curved surface.

[0054] Figure 3 It is an enlarged perspective view of a joint portion 522 included in the signal terminal 52 according to the embodiment.

[0055] like Figure 3 As shown, the signal terminal 52 includes an extension portion 521 and a bonding portion 522. The bonding portion 522 is a flat plate-shaped portion bonded to the circuit pattern 22b. The extension portion 521 is bent from one end of the bonding portion 522 and extends upward, and is configured to electrically connect the circuit pattern 22b to an external device of the semiconductor device 1.

[0056] In addition, the joint portion 522 of the signal terminal 52 may be formed to be smaller than the joint portion 512 of the power terminal 51, for example. That is, the joint surface of the joint portion 522 of the signal terminal 52 with the circuit pattern 22b may also have a smaller area than the joint surface of the joint portion 512 of the power terminal 51. This is because the amount of current flowing through the signal terminal 52 tends to be smaller than the amount of current flowing through the power terminal 51.

[0057] Furthermore, the joint portion 522 of the signal terminal 52 does not have a through portion like the joint portion 512 of the power terminal 51 .

[0058] The Cu sintered material 60 is interposed between the lower surface of the bonding portion 522 and the upper surface of the circuit pattern 22 b to bond them together.

[0059] In addition, the Cu sintered material 60 has a curled shape and covers the side surface of the joint portion 522. That is, the Cu sintered material 60 has a tapered shape extending from the upper surface of the joint portion 522 toward the circuit pattern 22b of the circuit substrate 20 on the side surface of the joint portion 522. However, the tapered portion of the Cu sintered material 60 may be bent between the upper surface of the joint portion 522 and the circuit pattern 22b. That is, in the joint portion 522 of the signal terminal 52, the inclined surface of the Cu sintered material 60 in the tapered portion may also be curved.

[0060] In addition, Figure 2 as well as Figure 3 In the embodiment, the extension portion 511 and the joint portion 512 of the power terminal 51, and the extension portion 521 and the joint portion 522 of the signal terminal 52 have portions bent at substantially right angles therebetween. However, these bent portions may also have obtuse angles, and the extension portion 511 and the joint portion 512, and the extension portion 521 and the joint portion 522 may also be connected by a gently curved surface.

[0061] As described above, the shape of the bent portion can be variously changed depending on the bending method when the long strip of metal material is bent to form the power terminal 51 and the signal terminal 52 having the joint portions 512 and 522 , respectively.

[0062] (Method for manufacturing semiconductor device)

[0063] Next, use Figure 4 to Figure 7 , an example of a method for manufacturing the semiconductor device 1 according to the embodiment will be described. Figure 4 to Figure 7 It is a cross-sectional view showing an example of the steps of the method for manufacturing the semiconductor device 1 according to the embodiment.

[0064] like Figure 4 As shown in (a), a semiconductor chip 30 is arranged on the circuit pattern 22b of the circuit substrate 20 via a Cu paste or an Ag paste, and the Cu paste or the Ag paste is heated and sintered to form a sintered material 32 that fixes the circuit pattern 22b and the semiconductor chip 30.

[0065] Furthermore, when the Cu paste or the Ag paste is sintered, it is also possible to heat them and apply a load to the semiconductor chip 30 to fix the semiconductor chip 30 more firmly to the circuit board 20 .

[0066] In addition, a wire 35 is formed to connect the gate electrode and source electrode of the semiconductor chip 30 (not shown) on the upper surface of the semiconductor chip 30 to the circuit pattern 22b of the circuit board. The gate electrode and source electrode of the semiconductor chip 30, the circuit pattern 22b of the circuit board and the wire 35 can be connected by ultrasonic bonding using ultrasonic waves, for example.

[0067] like Figure 4 As shown in (b) of FIG. 1 , the circuit board 20 on which the semiconductor chip 30 is mounted is fixed to the base plate 10 . More specifically, the circuit pattern 22 a on the back surface of the circuit board 20 is bonded to the base plate 10 using solder 12 , for example.

[0068] like Figure 4 As shown in FIG. 5 ( c ), a rectangular case 41 that is a part of the package 40 is fixed to the base plate 10 by a connection material 44 so as to surround the circuit board 20 and the semiconductor chip 30 .

[0069] like Figure 5 As shown in (a) of FIG. 2 , a non-pressurized Cu paste 60 p is applied on the circuit pattern 22 b of the circuit board 20 at the portion where the power terminal 51 and the signal terminal 52 are connected by a dispenser or the like.

[0070] like Figure 5 As shown in (b) of FIG. 2 , on the circuit pattern 22 b of the circuit board 20 , the power terminal 51 and the signal terminal 52 are arranged respectively via a non-pressurized Cu paste 60 p .

[0071] like Figure 6 As shown in (a), the non-pressurized Cu paste 60p between the power terminal 51 and the signal terminal 52 and the circuit pattern 22b of the circuit board 20 is sequentially heated and sintered. At this time, it is preferable to use a local heating device 100 that can locally heat the non-pressurized Cu paste 60p.

[0072] The local heating device 100 includes a local heating unit 11 and an inert gas supply unit 12 .

[0073] The local heating unit 11 includes a power supply line 111 and a heater 112 connected to the power supply line 111. The heater 112 can generate heat by supplying power from the power supply line 111 to the heater 112. The heater 112 may be, for example, a halogen heater or the like.

[0074] The inert gas supply unit 12 includes an inert gas supply line 121 and an inert gas supply pipe 122 connected to the inert gas supply line 121. An inert gas supply source (not shown) is connected to the other end of the inert gas supply line 121. The inert gas supply unit 12 can blow an inert gas such as nitrogen or a rare gas to the portion heated by the local heating unit 11 via the inert gas supply line 121 and the inert gas supply pipe 122.

[0075] When the non-pressurized Cu paste 60p is sintered, if the entire semiconductor device 1 in the process of being manufactured is heated, for example, a defect may occur due to melting of the solder 12 connecting the base plate 10 and the circuit board 20. However, by locally heating the non-pressurized Cu paste 60p between the power terminal 51 and the signal terminal 52 and the circuit pattern 22b of the circuit board 20 using the local heating device 100, it is possible to prevent other components from being heated.

[0076] In addition, by using the local heating device 100, the joint part including the non-pressurized Cu paste 60p is heated while blowing inert gas, thereby preventing the surface of the joint part such as the joints 512, 522 of the power terminal 51 and the signal terminal 52, and the circuit pattern 22b of the circuit substrate 20 from being oxidized.

[0077] Laser irradiation may be considered as a method of locally heating the non-pressurized Cu paste 60p. However, laser irradiation generates sputtering, so that debris of the laser-irradiated components such as the bonding portions 512 and 522 and the circuit pattern 22b may fly, which is not preferable.

[0078] Figure 6 (b) is an enlarged cross-sectional view of the joint portion of the power terminal 51 showing the heating condition of the local heating device 100. Figure 6 As shown in (b), when heating is performed by the local heating device 100, the extremely small-sized heating head 112a arranged at the front end of the heater 112 is brought into non-contact proximity with the joint 512 of the power terminal 51, the circuit pattern 22b of the circuit substrate 20, and the non-pressurized Cu paste 60p, and heating is performed while blowing inert gas from the inert gas supply pipe 122.

[0079] As a result, the non-pressurized Cu paste 60p is heated, and the organic solvent in the non-pressurized Cu paste 60p is vaporized and separated from the non-pressurized Cu paste 60p. In addition, as the organic solvent vaporizes, the density of the Cu particles in the non-pressurized Cu paste 60p increases, and the Cu particles are bonded to each other. In addition, along with this, the shape of the paste-like non-pressurized Cu paste 60p changes.

[0080] Specifically, the non-pressurized Cu paste 60p between the joint 512 of the power terminal 51 and the circuit pattern 22b of the circuit substrate 20 wets and spreads to the surroundings, forming the Cu sintered material 60 that covers the side of the joint 512 and has a curled shape toward the circuit pattern 22b. In addition, in the case of a pressurized Cu paste that is sintered while applying a load, such a curled shape cannot be obtained.

[0081] In addition, the non-pressurized Cu paste 60p bulges from the lower surface side of the joint portion 512 of the power terminal 51 into the through portion 513, and the Cu sintered material 60 is filled in the through portion 513. At this time, it is preferable to adjust the initial application amount of the non-pressurized Cu paste 60p so that the upper surface of the Cu sintered material 60 filled in the through portion 513 does not protrude more than half of the thickness of the joint portion 512, and more preferably, it is substantially equal to the height position of the upper surface of the joint portion 512.

[0082] In addition, although not shown in the figure, in the joint 522 of the signal terminal 52, when the local heating device 100 is heating, the heating head 112a at the front end of the heater 112 is also brought into non-contact proximity with the joint 522 of the signal terminal 52, the circuit pattern 22b of the circuit substrate 20, and the non-pressurized Cu paste 60p, and heating is performed while blowing inert gas from the inert gas supply pipe 122.

[0083] As a result, the organic solvent is vaporized and separated from the non-pressurized Cu paste 60p, and the Cu particles in the non-pressurized Cu paste 60p are bonded to each other. In addition, the shape of the paste-like non-pressurized Cu paste 60p changes accordingly.

[0084] In the bonding portion 522 of the signal terminal 52 without a through portion, the non-pressurized Cu paste 60p between the bonding portion 522 and the circuit pattern 22b wets and spreads to the surroundings to form a Cu sintered material 60 in a curled shape covering the side surface of the bonding portion 522 and facing the circuit pattern 22b.

[0085] In this way, by using the Cu sintered material 60 obtained by sintering the non-pressurized Cu paste 60 p , for example, the power terminal 51 and the signal terminal 52 can be connected to the circuit pattern 22 b of the circuit board 20 without applying a load.

[0086] like Figure 7 As shown in (a), the potting material 33 is injected into the space surrounded by the base plate 10 and the housing 41, and the semiconductor device 1 in the process of being manufactured is heated and cured in an oven. Thus, the potting material 33 is cured, and the insulation inside the housing 41 is maintained.

[0087] like Figure 7 As shown in (b), the cover 42 is covered and fixed to the upper end of the housing 41 with the connection material 44 interposed therebetween. Then, the upper ends of the extensions 511 and 521 of the power terminals 51 and the signal terminals 52 protruding from the upper surface of the cover 42 are bent.

[0088] As described above, the semiconductor device 1 according to the embodiment is manufactured.

[0089] (Comparative Example)

[0090] Next, use Figure 8 , an example of a case where the power terminal 51x of the comparative example or the power terminal 51 of the embodiment is connected to the circuit pattern 22b will be described.

[0091] Figure 8 2 is a cross-sectional view showing the connection between the power supply terminals 51 and 51x and the circuit pattern 22b according to the embodiment and the comparative example. Figure 8 (a) shows a case where the power supply terminal 51x of the comparative example is connected to the circuit pattern 22b. Figure 8 (b) shows a state where the power terminal 51 of the embodiment is connected to the circuit pattern 22b.

[0092] like Figure 8 As shown in (a), the power terminal 51x of the comparative example has a joint portion 512x joined to the circuit pattern 22b. However, no through portion is provided in the joint portion 512x. The non-pressurized Cu paste 60x is interposed between such a joint portion 512x and the circuit pattern 22b and is locally heated. As a result, the organic solvent in the non-pressurized Cu paste 60x is vaporized and separated from the non-pressurized Cu paste 60x.

[0093] At this time, the organic solvent is released exclusively from the side surface of the non-pressurized Cu paste 60x exposed from the gap between the bonding portion 512x and the circuit pattern 22b. Therefore, the density of Cu particles is increased in the center portion of the non-pressurized Cu paste 60x, and sintering proceeds relatively quickly.

[0094] On the other hand, near the end of the side surface of the non-pressurized Cu paste 60x, sintering is difficult due to the organic solvent separated from the center of the non-pressurized Cu paste 60x, and bubbles 61x are easily generated due to the vaporized organic solvent.

[0095] Such bubbles 61x are also generated in the center of the non-pressurized Cu paste 60x, but are more likely to be generated near the center and the end of the non-pressurized Cu paste 60x. Such bubbles 61x remain as voids in the Cu sintered material formed by heating.

[0096] Therefore, in the Cu sintered material of the comparative example, the density of Cu particles in the center is higher than that near the end, and the porosity near the end is higher than that in the center, and the center is dense and the end is sparse. Such a density difference will deteriorate the electrical characteristics and bonding strength of the bonding portion between the power terminal 51x and the circuit pattern 22b.

[0097] like Figure 8As shown in (b), in the power terminal 51 of the embodiment, as described above, the through portion 513 is provided in the joint portion 512. In this case, due to the local heating of the joint portion, the vaporized organic solvent is not only separated from the side of the non-pressurized Cu paste 60p exposed from the gap between the joint portion 512 and the circuit pattern 22b, but also separated from the upper end of the non-pressurized Cu paste 60p filled in the through portion 513.

[0098] As described above, the through portion 513 is provided at the center of the bonding surface of the bonding portion 512 with the circuit pattern 22b, and is arranged directly above the center of the non-pressurized Cu paste 60p. Therefore, the amount of organic solvent escaping from the vicinity of the end of the side of the non-pressurized Cu paste 60p can be reduced. Furthermore, the deviation of the amount of vaporized organic solvent escaping can be suppressed in the center of the non-pressurized Cu paste 60p and the vicinity of the end of the side of the non-pressurized Cu paste 60p, and the progress of sintering and the ease of generation of bubbles 61 caused by the vaporized organic solvent can be made consistent.

[0099] Thus, in the Cu sintered material 60 formed by heating, the deviation of the density and porosity of the Cu particles is also suppressed near the center and the end, and a Cu sintered material 60 with a small density difference is obtained. In addition, thereby, the overall porosity of the Cu sintered material 60 can also be reduced. Therefore, the electrical characteristics of the joint portion between the power terminal 51 and the circuit pattern 22b can be improved. Here, the porosity is, for example, the ratio of the area occupied by the void to the area occupied by the Cu sintered material 60 in a cross section cut in a direction perpendicular to the thickness direction of the joint 512.

[0100] Furthermore, as described above, the bonding portion 522 of the signal terminal 52 of the embodiment is configured such that the area of ​​the bonding surface with the circuit pattern 22p is smaller than that of the bonding portion 512 of the power terminal 51. Therefore, even if the through portion is not provided in the bonding portion 522 of the signal terminal 52, the deviation of the density and porosity of the Cu particles between the center portion and the vicinity of the end portions during sintering by heating can be suppressed, and the Cu sintered material 60 with a small density difference can be obtained.

[0101] (Summary)

[0102] The semiconductor device, for example, includes a semiconductor chip mounted on a circuit substrate having a circuit pattern. In addition, external terminals such as power terminals and signal terminals are sometimes connected to the circuit pattern of the circuit substrate. The circuit pattern and the external terminals are connected, for example, by ultrasonic bonding while applying a load. For example, a plurality of protrusions are provided at the front end of the bonding tool used for ultrasonic bonding, and these protrusions are sunk into the external terminals to apply ultrasonic vibrations, thereby firmly bonding the external terminals to the circuit pattern.

[0103] However, in the above method, the circuit substrate may be damaged due to the application of load and ultrasonic vibration. In addition, when the projection of the front end of the bonding tool is sunk into the external terminal, the debris of the external terminal is sometimes generated and scattered, causing short circuits such as wiring around the circuit pattern.

[0104] In order to solve the above problems, the inventors studied the method of connecting the external terminal and the circuit pattern without pressurization, and came up with the idea of ​​using a non-pressurized Cu paste. By heating the non-pressurized Cu paste and sintering it, a strong joint can be obtained even without pressurization, and the external terminal and the circuit pattern can be connected with high reliability.

[0105] However, when using non-pressurized Cu paste, other components are also heated due to the heat during sintering, and for example, the solder that fixes the circuit board to the base plate may melt. In addition, it is clear that when sintering the non-pressurized Cu paste, although the central part of the non-pressurized Cu paste is sintered relatively quickly, it is not sintered near the end, and the porosity becomes high and becomes sparse. The inventors of the present invention have further repeatedly conducted in-depth research and solved the above-mentioned problems.

[0106] According to the embodiment, the semiconductor device 1 includes a power terminal 51 including the same metal as the circuit pattern 22b of the circuit substrate 20 and electrically connected to the circuit pattern 22b, and the joining portion 512 of the power terminal 51 is joined to the circuit pattern 22b by a Cu sintered material 60 including particles of the same metal as the power terminal 51 and the circuit pattern 22b.

[0107] In this way, by using the Cu sintered material 60 in the connection between the circuit pattern 22b and the power terminal 51, the power terminal 51 and the circuit pattern 22b can be joined while suppressing damage to the circuit pattern 22b and the power terminal 51. In addition, it is also possible to suppress debris from scattering from the power terminal 51 and short-circuiting the surrounding wiring, etc. Therefore, a semiconductor device 1 with high reliability can be obtained. In addition, by using the Cu sintered material 60 containing the same metal as the circuit pattern 22b and the power terminal 51, the circuit pattern 22b and the power terminal 51 can be firmly joined.

[0108] According to the semiconductor device 1 of the embodiment, the power terminal 51 includes the flat plate-shaped bonding portion 512 bonded to the circuit pattern 22 b and the through portion 513 penetrating the bonding portion 512 in the thickness direction of the bonding portion 512 .

[0109] Thus, by having the through portion 513 in the joint portion 512, the density difference between the center portion and the vicinity of the end portion of the Cu sintered material 60 can be reduced, and the porosity of the entire Cu sintered material 60 can be reduced. Thus, the electrical characteristics and the bonding strength of the joint portion between the joint portion 512 and the circuit pattern 22b can be improved, and the power terminal 51 and the circuit pattern 22b can be connected with high reliability.

[0110] According to the semiconductor device 1 of the embodiment, the Cu sintered material 60 is interposed between the bonding portion 512 and the circuit pattern 22b and fills the through portion 513. This can improve the bonding strength between the bonding portion 512 and the circuit pattern 22b against stress that causes the bonding portion 512 and the circuit pattern 22b to shift laterally, i.e., shear stress.

[0111] According to the semiconductor device 1 of the embodiment, the Cu sintered material 60 has a curled shape and covers the side surface of the bonding portion 512. As described above, by using a non-pressurized Cu paste instead of a pressurized Cu paste, the Cu sintered material 60 having such a shape can be formed during sintering. By having the Cu sintered material 60 have a curled shape, the bonding strength between the bonding portion 512 and the circuit pattern 22b can be further improved.

[0112] According to the semiconductor device 1 of the embodiment, the through portion 513 has a circular shape when viewed from the upper surface of the bonding portion 512, and the center point of the through portion 513 viewed from the upper surface of the bonding portion 512 substantially coincides with the center point of the bonding surface of the bonding portion 512 with the circuit pattern 22b. By providing the through portion 513 at such a position, the density difference between the central portion and the vicinity of the end of the Cu sintered material 60 can be further reduced.

[0113] According to the semiconductor device 1 of the embodiment, the signal terminal 52 is further provided, which is made of the same metal as the circuit pattern 22b and is electrically connected to the circuit pattern 22b, and the Cu sintered material 60 is also interposed between the junction 522 of the signal terminal 52 and the circuit pattern 22b. Thus, by applying the Cu sintered material 60 also to the junction between the signal terminal 52 and the circuit pattern 22b, the signal terminal 52 can be joined to the circuit pattern 22b while suppressing damage.

[0114] According to the semiconductor device 1 of the embodiment, the joint portion 522 of the signal terminal 52 is smaller than the joint portion 512 of the power terminal 51, and the through portion 513 is selectively formed in the joint portion 512 of the power terminal 51 and the joint portion 522 of the signal terminal 52. In this way, the joint portion 522 of the signal terminal 52 is often formed smaller than the joint portion 512 of the power terminal 51. In this case, even if the through portion is not provided in the joint portion 522 of the signal terminal 52, the deviation of the density difference between the center portion and the vicinity of the end portion of the Cu sintered material 60 can be suppressed.

[0115] According to the manufacturing method of the semiconductor device 1 of the embodiment, when connecting the power terminal 51 and the circuit pattern 22b, no load is applied to the power terminal 51 and the circuit pattern 22b, and the non-pressurized Cu paste 60p is locally heated and sintered. As a result, for example, the power terminal 51 and the circuit pattern 22b can be bonded while suppressing damage caused by the application of load and ultrasonic bonding. In addition, since the non-pressurized Cu paste 60p is locally heated, it is possible to suppress other components from being heated and damaged.

[0116] According to the manufacturing method of the semiconductor device 1 of the embodiment, when the non-pressurized Cu paste 60p is sintered, an inert gas is blown into the non-pressurized Cu paste 60p, and the heating head 112a of the heater 112 is brought close to the joint 512 of the power terminal 51 in a non-contact manner, thereby locally heating the non-pressurized Cu paste 60p.

[0117] In this way, the non-pressurized Cu paste 60p is sintered by local heating, thereby preventing other components from being heated. In addition, by blowing an inert gas when heating the non-pressurized Cu paste 60p, oxidation of the bonding portion 512 and the circuit pattern 22b can be prevented.

[0118] According to the manufacturing method of the semiconductor device 1 of the embodiment, when the non-pressurized Cu paste 60p is interposed between the joint 512 and the circuit pattern 22b, the usage amount of the non-pressurized Cu paste 60p is adjusted so that the thickness of the Cu sintered material 60 generated by sintering the non-pressurized Cu paste 60p from the bonding interface with the circuit pattern 22b to the through portion 513 at the upper end is greater than the thickness of the joint 512 and less than 1.5 times the thickness of the joint 512.

[0119] In this way, the bonding strength of the joint portion 512 and the circuit pattern 22b with respect to shear stress is improved by setting the through portion 513 to be sufficiently filled with the Cu sintered material 60. On the other hand, there is no need to sinter the remaining non-pressurized Cu paste 60p that greatly exceeds the upper surface of the joint portion 512, so the non-pressurized Cu paste 60p is easily sintered and the sintering time can be shortened.

[0120] (Variant 1)

[0121] Next, use Fig. 9 A semiconductor device according to Modification 1 of the embodiment will be described. The semiconductor device according to Modification 1 is different from the above-described embodiment in the shape of a through portion 513s provided in a bonding portion 512 of a power terminal 51s.

[0122] Fig. 9 FIG. 5 is an enlarged view of a joint portion 512 provided in a power terminal 51s according to a first modification of the embodiment. Fig. 9 (a) is a three-dimensional view of the joint 512, Fig. 9 (b) is a top view of the lower surface side of the bonding portion 512.

[0123] In addition, Fig. 9 In the present invention, the same reference numerals are used for the same structures as those in the above-mentioned embodiment, and the description thereof may be omitted.

[0124] like Fig. 9 As shown, the joint portion 512 of the power terminal 51s of the modification 1 is provided with a through portion 513s having a quadrilateral shape when viewed from the upper surface. In this case, the shape of the through portion 513s can be a square at least in design. However, from the perspective of processing accuracy, this does not mean that the final shape of the through portion 513s is also a square.

[0125] like Fig. 9 As shown in (b), the through portion 513 of Modification 1 is also provided at the lower surface of the joint portion 512, that is, the center portion of the joint surface of the joint portion 512 and the circuit pattern 22b. That is, the center point of the through portion 513s observed from the upper surface is substantially consistent with the center point of the joint surface of the joint portion 512.

[0126] Such a penetration portion 513 of Modification 1 can also be formed by, for example, wire discharge machining or the like.

[0127] According to the semiconductor device of Modification 1, the through portion 513s has a quadrilateral shape when viewed from the upper surface of the bonding portion 512, and the center point of the through portion 513s viewed from the upper surface of the bonding portion 512 substantially coincides with the center point of the bonding surface of the bonding portion 512 with the circuit pattern 22b. Thus, the same effect as that of the semiconductor device of the above-mentioned embodiment is achieved.

[0128] In addition, when the width of the through-portion 513s is made equal to the diameter of the circular through-portion 513 in the above-mentioned embodiment, the opening area of ​​the quadrilateral through-portion 513s at the joint 512 becomes larger. As a result, the amount of organic solvent escaping from the upper end of the central portion of the non-pressurized Cu paste 60p can be further increased. Therefore, the density difference between the central portion and the vicinity of the end of the Cu sintered material 60 can be further reduced, and the porosity of the entire Cu sintered material 60 can be reduced.

[0129] (Variant 2)

[0130] Next, use Fig.10 A semiconductor device according to a second modification of the embodiment will be described. In the semiconductor device according to the second modification, the power supply terminal has through portions 513e, 513u, 513r, and 513c in the bonding portion 512, which have shapes further different from those of the above-described embodiment.

[0131] Fig.10 FIG. 2 is a top view of the lower surface side of the joint portion 512 provided in the power terminal of the modification example 2 of the embodiment. Fig.10 In the present invention, the same reference numerals are used for the same structures as those in the above-mentioned embodiment, and the description thereof may be omitted.

[0132] exist Fig.10 In the example (a), the through hole portion 13e of the modification example 2 has an ellipse having a major axis in the longitudinal direction of the bonding portion 512. The through portion 513e of the modification example 2 having an ellipse is also provided at the lower surface of the bonding portion 512, that is, the center portion of the bonding surface of the bonding portion 512 with the circuit pattern 22b. That is, the center point of the through portion 513e observed from above substantially coincides with the center point of the bonding surface of the bonding portion 512.

[0133] exist Fig.10 In the example (b) of FIG. 1 , the through portion 513u of the modification 2 is open at the other end side opposite to the one end of the joint portion 512 having the bent portion with the extension portion 511. In addition, the end of the through portion 513u has a curved surface on the one end side of the joint portion 512. That is, the through portion 513u has a U-shape when viewed from above.

[0134] exist Fig.10 In the example (c), the through hole portion 13r of the modification example 2 has a rectangular shape having long sides in the longitudinal direction of the bonding portion 512. The through portion 513r of the modification example 2 having a rectangular shape is also provided at the lower surface of the bonding portion 512, that is, the center portion of the bonding surface of the bonding portion 512 with the circuit pattern 22b. That is, the center point of the through portion 513r observed from the upper surface substantially coincides with the center point of the bonding surface of the bonding portion 512.

[0135] exist Fig.10 In the example of (d), the through portion 513c of the modification 2 is open at the other end side opposite to the one end of the joint portion 512 having the bent portion with the extension portion 511. In addition, the end of the through portion 513c has a square shape on the one end side of the joint portion 512. That is, the through portion 513c viewed from above has a rectangular shape with one short side open.

[0136] According to the semiconductor device of Modification 2, the shape of the through-holes 513e, 513u, 513r, and 513c viewed from the upper surface of the bonding portion 512 has a long side direction and a short side direction. This provides the same effects as those of the semiconductor device of the above embodiment.

[0137] In addition, when the width of the through-portions 513e and 513r in the short-side direction is made equal to the width of the circular through-portion 513 of the above-mentioned embodiment and the quadrilateral through-portion 513s of the above-mentioned modification 1, the opening area of ​​the through-portions 513e and 513r in the modification 2 at the joint 512 is increased. As a result, the amount of organic solvent released from the upper end of the central portion of the non-pressurized Cu paste 60p can be further increased, the density difference between the central portion and the vicinity of the end of the Cu sintered material 60 can be further reduced, and the porosity of the entire Cu sintered material 60 can be reduced.

[0138] According to the semiconductor device of Modification 2, the through portions 513u and 513c are open at the other end side of the joint portion 512. Thus, the opening area at the joint portion 512 can be further increased. Therefore, the amount of organic solvent released from the upper end of the center portion of the non-pressurized Cu paste 60p can be further increased, the density difference between the center portion and the vicinity of the end portion of the Cu sintered material 60 can be further reduced, and the porosity of the entire Cu sintered material 60 can be reduced.

[0139] In addition, in the above-mentioned embodiment and modification examples 1 and 2, the semiconductor chip 30 is a semiconductor chip 30 made of SiC. However, even if the semiconductor chip 30 is other materials such as Si, GaAs, GaN, etc., the above-mentioned embodiment and the configuration of modification examples 1 and 2 can be applied. In addition, the semiconductor chip 30 is not limited to the above-mentioned MOSFET, and can also be a semiconductor chip of a different type from MOSFET, such as an insulated gate bipolar transistor (IGBT).

[0140] In the above-described embodiment and Modifications 1 and 2, only one through portion 513 , 513 s , 513 e , 513 u , 513 r , 513 c is provided. However, a plurality of through portions may be provided in the joining portion 512 .

[0141] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope or subject matter of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A semiconductor device comprising: an insulating substrate having a circuit pattern; a semiconductor chip fixed on the insulating substrate and electrically connected to the circuit pattern; and a power terminal comprising the same metal as the circuit pattern and electrically connected to the circuit pattern, The power terminal has: a flat plate-shaped joint portion joined to the circuit pattern; a through portion that penetrates the joining portion in a thickness direction of the joining portion; and The extension portion is bent from one end of the joint portion and extends upward, and is configured to connect the circuit pattern to an external device. The joining portion and the circuit pattern are joined by a joining material containing particles of the same metal as that of the power terminal and the circuit pattern.

2. The semiconductor device according to claim 1, wherein The bonding material is interposed between the bonding portion and the circuit pattern and is filled in the through portion.

3. The semiconductor device according to claim 2, wherein: The thickness of the bonding material at the through portion from the bonding interface with the circuit pattern to the upper end of the bonding material is equal to or greater than the thickness of the bonding portion and less than 1.5 times the thickness of the bonding portion.

4. The semiconductor device according to claim 1, wherein The bonding material has a curled shape and covers a side surface of the bonding portion.

5. The semiconductor device according to claim 1, wherein The bonding material contains voids therein.

6. The semiconductor device according to claim 1, wherein The bonding material is derived from a non-pressurized metal paste containing the particles in an organic solvent and capable of being sintered without pressure.

7. The semiconductor device according to claim 1, wherein The through portion has a circular or quadrilateral shape when viewed from the upper surface of the joining portion.

8. The semiconductor device according to claim 1, wherein The shape of the through portion viewed from the upper surface of the joining portion has a long side direction and a short side direction.

9. The semiconductor device according to claim 8, wherein: The through portion opens on the other end side of the joining portion.

10. The semiconductor device according to claim 7 or 8, wherein: A center point of the through portion viewed from an upper surface of the bonding portion and a center point of a bonding surface of the bonding portion with the circuit pattern substantially coincide with each other.

11. The semiconductor device according to claim 1, wherein The semiconductor device further includes a signal terminal, the signal terminal including the same metal as the circuit pattern and electrically connected to the circuit pattern. The bonding material is also interposed between the bonding portion of the signal terminal and the circuit pattern.

12. The semiconductor device according to claim 11, wherein The bonding portion of the signal terminal is smaller than the bonding portion of the power terminal. The through portion is selectively formed at the joint portion of the power terminal out of the joint portion of the power terminal and the joint portion of the signal terminal.

13. A method for manufacturing a semiconductor device, A semiconductor chip is fixed on an insulating substrate having a circuit pattern and is electrically connected to the circuit pattern. electrically connecting a power supply terminal including the same metal as the circuit pattern to the circuit pattern, The power terminal has: a flat plate-shaped joint portion joined to the circuit pattern; a through portion that penetrates the joining portion in a thickness direction of the joining portion; and an extension portion, which is bent from one end of the joint portion and extends upward, When the power supply terminal is connected to the circuit pattern, A non-pressurized metal paste containing particles of the same metal as the power terminal and the circuit pattern and capable of being sintered without pressure is interposed between the joint portion of the power terminal and the circuit pattern, The non-pressurized metal paste is locally heated and sintered without applying a load to the power terminal and the circuit pattern.

14. The method for manufacturing a semiconductor device according to claim 13, wherein: When the non-pressurized metal paste is sintered, While blowing an inert gas toward the non-pressurized metal paste, a heating head of a heater is brought close to the joining portion of the power terminal in a non-contact manner to locally heat the non-pressurized metal paste.

15. The method for manufacturing a semiconductor device according to claim 13, wherein: When the non-pressurized metal paste is sintered, The non-pressurized metal paste is filled into the through portion.

16. The method for manufacturing a semiconductor device according to claim 15, wherein: When the non-pressurized metal paste is interposed between the bonding portion and the circuit pattern, The amount of the non-pressurized metal paste used is adjusted so that the thickness of the through portion from the bonding interface of the bonding material produced by sintering the non-pressurized metal paste with the circuit pattern to the upper end is greater than the thickness of the bonding portion and less than 1.5 times the thickness of the bonding portion.

17. The method for manufacturing a semiconductor device according to claim 13, wherein: The through portion has a circular or quadrilateral shape when viewed from the upper surface of the joining portion.

18. The method for manufacturing a semiconductor device according to claim 13, wherein: The shape of the through portion viewed from the upper surface of the joining portion has a long side direction and a short side direction.

19. The method for manufacturing a semiconductor device according to claim 18, wherein: The through portion opens on the other end side of the joining portion.

20. The method for manufacturing a semiconductor device according to claim 17 or 18, wherein: A center point of the through portion viewed from an upper surface of the bonding portion and a center point of a bonding surface of the bonding portion with the circuit pattern substantially coincide with each other.

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