Semiconductor device and manufacturing method thereof

Abstract

The present disclosure pertains to a semiconductor device and a method for manufacturing same, and the purpose of the present disclosure is to provide a semiconductor device and a method for manufacturing same, with which the outermost surface of a surface electrode is modified by laser irradiation to reduce cost and improve assemblability of the semiconductor device. In the present disclosure, provided are: a surface electrode solder joint; solder; a resin sealing material; and a semiconductor element mounted under the surface electrode solder joint. The surface electrode solder joint includes a first laser-modified section in which the outermost surface is oxidized and roughened; and a first solder joint region that is joined to the solder. The laser-modified section is covered with the resin sealing material.

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor device and a manufacturing method thereof, and more particularly to a semiconductor device suitable for use in a power converter such as an inverter, and a manufacturing method thereof. [Background technology]

[0002] Known power semiconductor devices used in inverters and the like have a structure in which the surface electrodes of a semiconductor element are soldered to external electrodes. When a semiconductor device with this structure is subjected to thermal stress, such as a power cycle or thermal cycle, thermal stress occurs due to the difference in the linear expansion coefficients of the materials. This causes peeling at the material interface at the outermost periphery of the surface electrode, and as this peeling progresses, problems such as cracks in the surface electrode of the semiconductor element occur.

[0003] Patent Documents 1 and 2 disclose a technique for preventing cracks in the surface electrodes of semiconductor elements, in which a coating film made of polyimide is formed on the material boundary portion of the outermost periphery of the surface electrode. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 6156381

[0005] [Patent Document 2] Japanese Patent Publication No. 2019-201160 Summary of the Invention [Problem to be solved by the invention]

[0006] However, forming a polyimide film on the surface electrodes increases the complexity of the manufacturing process, resulting in increased manufacturing costs, and also reduces assembly efficiency due to increased chip warpage caused by polyimide film stress and reduced solder joint strength caused by the polyimide curing heat treatment.

[0007] In order to solve the above-mentioned problems, the present disclosure aims to provide a semiconductor device and a manufacturing method thereof, which modify the outermost surface of a front electrode by laser irradiation, thereby reducing the cost of the semiconductor device and improving assembly ease. [Means for solving the problem]

[0008] A first aspect of the present disclosure is a semiconductor device including a surface electrode solder joint, solder, a resin encapsulant, and a semiconductor element mounted below the surface electrode solder joint, wherein the surface electrode solder joint has a first laser-modified portion whose outermost surface is oxidized and roughened, and a first solder joint region joined to the solder, and the laser-modified portion is covered with the resin encapsulant. It is formed by irradiating a laser beam with a pulse, and is an area that can be processed with a single pulse irradiation. It is formed by arranging multiple processing areas so that they surround the outer periphery of the surface electrode solder joint. It is preferably a semiconductor device.

[0009] A second aspect of the present disclosure is a method for manufacturing a semiconductor device including a surface electrode solder joint, a solder, and a resin encapsulant, the method including the steps of: forming a laser-modified portion by irradiating a portion of the surface electrode solder joint with pulsed laser light; performing solder bonding on the surface electrode solder joint; and performing resin encapsulation using the resin encapsulant so as to cover the laser-modified portion. The laser modified area is formed by arranging multiple processing areas, which are areas that can be processed with a single pulse irradiation, so that they surround the outer periphery of the surface electrode solder joint. Semiconductor device manufacturing method in It is preferable that there is. [Effects of the Invention]

[0010] According to aspects of the present disclosure, it is possible to provide a semiconductor device and a method for manufacturing the same that can reduce costs and improve assembly efficiency by modifying the outermost surface of a front electrode by laser irradiation. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing a cross-sectional view of a semiconductor device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the semiconductor device according to the first embodiment before laser irradiation. [Figure 3]FIG. 2 is a cross-sectional view showing the semiconductor device after laser irradiation according to the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing the semiconductor device after soldering according to the first embodiment. [Figure 5] 1 is a cross-sectional view showing a semiconductor device after being sealed with resin according to the first embodiment. [Figure 6] 1 is a plan view showing a semiconductor element according to a first embodiment before laser irradiation. [Figure 7] FIG. 2 is a plan view showing the semiconductor element after laser irradiation according to the first embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing a semiconductor device according to a fourth embodiment. [Figure 9] FIG. 13 is a cross-sectional view showing a semiconductor device according to a seventh embodiment. [Figure 10] FIG. 13 is a cross-sectional view showing a semiconductor device according to an eighth embodiment. [Figure 11] FIG. 22 is a plan view showing a semiconductor element according to a tenth embodiment. [Figure 12] FIG. 23 is a plan view showing a semiconductor element information formation area according to a tenth embodiment. [Figure 13] FIG. 23 is a plan view showing a semiconductor element information formation area according to a tenth embodiment. [Figure 14] FIG. 22 is a plan view showing a semiconductor element according to an eleventh embodiment. [Figure 15] FIG. 22 is a cross-sectional view showing a semiconductor device according to an eleventh embodiment. [Figure 16] FIG. 23 is a plan view showing a semiconductor element according to a twelfth embodiment. [Figure 17] FIG. 23 is a plan view showing a semiconductor element according to a thirteenth embodiment. [Figure 18] FIG. 23 is a cross-sectional view showing a semiconductor device according to a fourteenth embodiment before laser irradiation. [Figure 19] FIG. 23 is a cross-sectional view showing a semiconductor device after resin sealing according to a fourteenth embodiment. [Figure 20] FIG. 23 is a plan view showing a rear surface electrode before laser irradiation according to a fourteenth embodiment. [Figure 21]FIG. 23 is a plan view showing the rear surface electrode after laser irradiation according to the fourteenth embodiment. [Figure 22] FIG. 23 is a cross-sectional view showing an end portion of a semiconductor element before being sealed with resin according to a fifteenth embodiment. [Figure 23] FIG. 23 is a plan view showing a semiconductor element before being sealed with resin according to a fifteenth embodiment. [Figure 24] FIG. 23 is a plan view showing a semiconductor element according to a sixteenth embodiment before being sealed with resin. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiment 1 1 is a diagram showing a cross-sectional view of a semiconductor device according to a first embodiment. The semiconductor device 100 includes a semiconductor element 2. The semiconductor element 2 has a back surface electrode 4 on its back surface. The back surface electrode 4 is formed of a metal film and is connected to a base plate 3 having a heat dissipation function using a conductive bonding material 5 such as solder. The base plate 3 is formed of a metal such as Cu and is connected to an insulating layer 1.

[0013] The semiconductor element 2 also has a surface electrode solder joint 6 on its surface. The surface electrode solder joint 6 is formed of a metal film. The surface electrode solder joint 6 is an electrode that carries the main current of the semiconductor element 2. The surface electrode solder joint 6 is connected to an external electrode 10 made of a metal such as Cu using a conductive bonding material 5 made of solder.

[0014] The semiconductor element 2 also has surface electrode wire pads 8 on its surface. The surface electrode wire pads 8 are formed of a metal film. The surface electrode wire pads 8 are used to drive and control the semiconductor element 2. The surface electrode wire pads 8 are connected to external electrodes 14, which are electrically separated from the surface electrode solder joints 6, using conductive wiring material 12 such as aluminum wire.

[0015] The entire semiconductor device 100 is sealed with a sealing material 16 to ensure electrical insulation, environmental resistance, etc. The sealing material 16 is made of an insulating material such as epoxy resin.

[0016] In a semiconductor device having the above structure, when subjected to thermal stress such as power cycles or thermal cycles, thermal stress occurs at the edges of the surface electrode solder joints 6 of the semiconductor element due to the difference in the linear expansion coefficients of the materials. This causes interfacial peeling between the surface electrode, the conductive bonding material, and the encapsulant. If this interfacial peeling progresses due to repeated thermal stress, cracks will form in the metal film forming the surface electrode of the semiconductor element. To prevent this metal film cracking, Patent Documents 1 and 2 disclose techniques for forming a coating film made of polyimide on the edges of the surface electrode of the semiconductor element. This forms a stress relief layer and improves adhesion to the underlying metal film, thereby suppressing metal film cracking.

[0017] However, forming a polyimide film causes problems in terms of manufacturing cost and assembly. Therefore, in the semiconductor device 100 according to this embodiment, instead of forming a polyimide film, a laser is irradiated onto the outermost surface of the surface electrode. This results in a laser-modified portion. 36 By forming this, the degree of adhesion at the interface between the surface electrode and the sealing material is improved, and peeling at the interface between the materials is suppressed.

[0018] A manufacturing process of the semiconductor device 100 will be described. FIG. 2 is a cross-sectional view showing the semiconductor device according to the first embodiment before laser irradiation. The surface electrode solder joint 6 of the semiconductor element includes a first metal film 20. The first metal film 20 contains Al and functions as an adhesive film. A second metal film 22 is formed on the first metal film 20. The second metal film 22 contains Ni and functions as a bonding film. A third metal film 24 is formed on the second metal film 22. The third metal film 24 contains Au and functions as an anti-oxidation film.

[0019] Laser irradiation area 25 indicates an area on the outermost layer of surface electrode solder joint 6 that is irradiated with laser light 26. Processing area 27 indicates a circular area that can be processed with a single pulse of laser light 26. Furthermore, a coating film 28 is formed on first metal film 20 at a position that contacts the ends of second metal film 22 and third metal film 24.

[0020] A semiconductor substrate 30 is disposed below the surface electrode solder joint 6. The semiconductor substrate 30 includes a trench 32 filled with PolySi. An oxide film 34 is formed on the trench 32.

[0021] 3 is a cross-sectional view showing the semiconductor device after laser irradiation according to embodiment 1. Here, the state after the laser light 26 is irradiated onto the outermost layer of the third metal film 24 is shown.

[0022] The laser modified portion 36 indicates the region irradiated with the laser beam 26. In the laser modified portion 36, solid diffusion of Au and Ni occurs due to the thermal energy from the laser beam 26. That is, Au contained in the third metal film 24 diffuses into the second metal film 22, forming a Ni oxide layer on the surface.

[0023] 4 is a cross-sectional view showing the semiconductor device after solder bonding according to embodiment 1. In the area where the solder 38 has spread, an intermetallic compound layer 40 is formed by reaction with the third metal film 24. On the other hand, the laser-modified portion 36 has a Ni oxide layer formed on its surface, which inhibits solder wetting.

[0024] Furthermore, in the laser-modified area 36, ​​the surface is concentrically scraped away by pulsed irradiation of the laser light 26. The area processed by one pulse irradiation is the processed area 27 described above. This process is repeated until the entire laser-modified area 36 is processed. As a result, the surface is roughened. This roughening process increases the contact area between the solder and the surface electrode, and increases the surface tension at the interface between the solder and the surface electrode. This further inhibits solder wetting.

[0025] When laser processing, the type of laser is selected taking into consideration the characteristics of the material to be irradiated with the laser. In this disclosure, a laser type suitable for processing Au is used. In this case, due to the laser wavelength, the size that can be processed with a single pulse irradiation is approximately several tens of micrometers in diameter. However, if the area of ​​the Ni oxide layer formed by laser irradiation is small, the Ni oxide layer will be reduced if a solder material or solder joining process with a high Ni oxide reducing power is used. As a result, there is a possibility that the solder will wet and spread.

[0026] In this embodiment, the processed region 27 is formed in a multiple ring shape, so that it surrounds the outermost periphery of the surface electrode. This ensures that the Ni oxide layer has a certain area or more, improving the margin for the reduction action of the Ni oxide layer. As a result, the solder does not wet and spread to the laser-modified portion 36 during the soldering process. Furthermore, even after soldering, a certain amount of the Ni oxide layer remains exposed on the laser-modified portion 36.

[0027] 5 is a cross-sectional view showing the semiconductor device after resin sealing according to the first embodiment. When resin sealing is performed, the surface of the laser-modified portion 36 is covered with the resin sealing material 42. That is, a region consisting of the laser-modified surface and the sealing material interface is formed. As described above, the surface of the laser-modified portion 36 is roughened. Therefore, the anchor effect improves the adhesion strength at the interface between the laser-modified portion 36 and the resin sealing material 42.

[0028] 6 is a plan view showing the semiconductor element before laser irradiation according to embodiment 1. The semiconductor element 2 has, on its surface layer, surface electrode solder joints 6 and surface electrode wire pads 8. Processing region 27 indicates an area that can be processed by one pulse irradiation of laser light 26.

[0029] 7 is a plan view showing the semiconductor element after laser irradiation according to the first embodiment. The laser modified portion 36 indicates the area to be irradiated with the laser light 26. A single pulse of the laser light 26 can process only the range of the processing area 27. By repeating this process, the range of the laser modified portion 36 is processed. In the surface electrode solder joint 6, the area other than the laser modified portion 36 is referred to as the solder joint area 37.

[0030] As described above, this embodiment can prevent cracks in the metal film without forming a polyimide film. This eliminates the need for manufacturing processes such as photolithography, dispense coating, and heat treatment, which were previously required to form a polyimide film. As a result, the cost of manufacturing semiconductor devices can be reduced. Furthermore, because stress caused by the polyimide film and heat treatment for hardening the polyimide film are not required, chip warpage can be reduced and solder wettability can be improved. As a result, improved assembly and quality can be expected. Furthermore, the surface roughness and processing width of the laser-modified region 36 can be adjusted by adjusting the laser irradiation conditions. In other words, the solder wettability prevention effect and adhesion strength with the encapsulant can be intentionally controlled, thereby increasing the design flexibility of the semiconductor device.

[0031] Embodiment 2 The second embodiment differs from the first embodiment in that the processed regions 27 are arranged at regular intervals. In the semiconductor device according to the first embodiment, if the processed regions 27 are arranged arbitrarily, an unirradiated portion will be generated in part of the laser modified portion 36. In the unirradiated portion, the surface of the third metal film 24 will remain exposed. Therefore, when the semiconductor device is sealed with a resin sealing material 42, an interface between the third metal film 24 and the resin sealing material 42 will be formed in a partial region, reducing the adhesive strength.

[0032] Therefore, in this embodiment, the processed regions 27 are arranged so that they overlap at regular intervals, thereby preventing the generation of unirradiated areas. As a result, the interface between the laser modified portion 36 and the resin sealing material 42 is formed uniformly, improving the adhesion strength and achieving high reliability of the semiconductor device.

[0033] Embodiment 3 The third embodiment differs from the previous embodiments in that the width of the laser-modified portion 36 is at least 100 μm or more. In the semiconductor device according to the first embodiment, the Ni oxide layer on the surface of the laser-modified portion 36 may be reduced during the soldering process. In this case, the solder spreads over the laser-modified portion 36, narrowing the width of the laser-modified portion 36. If this width is narrowed beyond a certain level, the area where the laser-modified portion 36 and the resin sealing material 42 come into contact after sealing with the resin sealing material 42 will be narrow, which will result in a decrease in adhesion strength.

[0034] Generally, when the reducing power of Ni oxidation in the soldering process is strong, the surface electrode Solder joints As a result, it has been confirmed that Ni oxide is reduced in an area several tens of micrometers from the laser-modified area, causing the solder to wet and spread. Therefore, the width of the laser-modified area is formed to be at least 100 μm. This ensures a stable area where the laser-modified area and the sealing material come into contact, improving adhesion strength and increasing the reliability of the semiconductor device.

[0035] Embodiment 4 8 is a cross-sectional view showing a semiconductor device according to embodiment 4. Embodiment 4 differs from the previous embodiments in that the energy density applied to the laser modified portion 36 is changed for each region.

[0036] In the semiconductor device according to the first embodiment, in order to enhance the laser modification effect, it is necessary to increase the energy of the irradiated laser, which may cause the influence of the energy to spread to non-laser irradiated areas, resulting in the deposition of the second metal film 22, which may oxidize the surface and reduce the solder wettability.

[0037] Therefore, in this embodiment, the energy density of the laser irradiated is reduced only in the region in contact with the surface electrode solder joint 6. That is, the energy density of the laser irradiated to the laser-modified portion 36a is set lower than that of the laser-modified portion 36b. This minimizes the impact of reduced solder wettability in non-laser-irradiated regions. Even if the energy density is reduced, the surface of the laser-modified portion 36a becomes a Ni oxide layer. Therefore, the solder does not spread onto the laser-modified portion 36a during the soldering process. Furthermore, by maintaining the energy density of the laser irradiated to the laser-modified portion 36b, the adhesion at the interface between the laser-modified portion 36b and the resin sealing material 42 is not impaired.

[0038] Fifth embodiment The fifth embodiment differs from the previous embodiments in that the laser light absorptance of each metal film is changed. Consider the case where the laser irradiation energy is too high in the semiconductor device according to the first embodiment, or where the laser light absorptance of the first metal film 20 or the second metal film 22 is higher than that of the third metal film 24. In this case, heat generated by the laser irradiation melts the metal film into the semiconductor substrate bulk, causing abnormalities in the electrical characteristics of the semiconductor element.

[0039] Therefore, in this embodiment, the surface electrode is formed so that the laser light absorption rate of the third metal film 24 is higher than that of the first metal film 20 and the second metal film 22. As a result, when the outermost surface of the third metal film 24 is irradiated with a laser, less heat is generated in the underlying first metal film 20 and second metal film 22. This reduces the risk of the metal films melting due to the heat of laser irradiation, thereby reducing damage to the semiconductor element.

[0040] Sixth embodiment The sixth embodiment differs from the previous embodiments in that the total thickness of the first metal film 20 and the second metal film 22 is at least 1 μm or more, and the thickness of the third metal film 24 is 0.2 μm or less.

[0041] As mentioned above, in the semiconductor device according to the first embodiment, heat generated by laser irradiation can cause abnormalities in the electrical characteristics of the semiconductor element. Therefore, in this embodiment, the total thickness of the first metal film 20 and the second metal film 22 is set to at least 1 μm, and the thickness of the third metal film 24 is set to 0.2 μm or less. This allows the film to be laser-processed to be thin and the film not to be laser-processed to be thick, making it possible to form the Ni oxide layer with low power. As a result, damage to the semiconductor element caused by heat during laser processing can be reduced.

[0042] Embodiment 7 9 is a cross-sectional view showing a semiconductor device according to embodiment 7. Embodiment 7 differs from the previous embodiments in that an ineffective cell region 44 is provided directly below the laser modified portion .

[0043] As described above, in the semiconductor device according to the first embodiment, heat generated by laser irradiation causes abnormalities in the electrical characteristics of the semiconductor element. Therefore, in this embodiment, the area directly below the laser-modified portion 36 is designated as an inactive cell region 44. In the inactive cell region 44, the trenches 32 and oxide films 34 necessary for the function of the semiconductor element are not implemented. This reduces the number of trenches 32 and oxide films 34 that are affected by the heat during laser processing, thereby reducing damage to the semiconductor element function in the entire semiconductor device.

[0044] Embodiment 8 10 is a cross-sectional view showing a semiconductor device according to embodiment 8. Embodiment 8 differs from the previous embodiments in that a barrier metal layer 46 is provided at the boundary between the first metal film 20 and the oxide film 34.

[0045] As described above, in the semiconductor device according to the first embodiment, heat generated by laser irradiation causes abnormalities in the electrical characteristics of the semiconductor element. Therefore, in this embodiment, a barrier metal layer 46 is provided at the boundary between the first metal film 20 and the oxide film 34. This prevents the Al forming the first metal film 20 from solid-state diffusing to the semiconductor substrate interface, thereby reducing damage to the semiconductor element caused by heat during laser processing.

[0046] Embodiment 9 The ninth embodiment differs from the previous embodiments in that the coating film 28 is formed to have a high reflectance to the laser light 26. In the semiconductor device according to the first embodiment, the coating film 28 is disposed on the outermost periphery of the surface electrode solder joint 6. An oxide film or an insulating film may be disposed under the coating film 28. In this case, irradiation with the laser light 26 may damage the surface of the oxide film or insulating film.

[0047] Therefore, in this embodiment, the coating film 28 is formed to have a high reflectance to the laser beam 26. An example of a film with a high reflectance to the laser beam 26 is a polyimide film with a low refractive index. This minimizes damage to the oxide film or insulating film caused by the laser beam 26, which is expected to improve the quality of the semiconductor device.

[0048] Embodiment 10 11 is a plan view showing a semiconductor element according to embodiment 10. Embodiment 10 differs from the previous embodiments in that a semiconductor element information formation area 48 is provided in part of the laser modified section 36.

[0049] In the semiconductor device according to the first embodiment, the entire area of ​​the laser modified section 36 is irradiated with the laser light 26, which poses a problem of long laser irradiation time. Therefore, in the present embodiment, a semiconductor element information formation area 48 is provided in part of the laser modified section 36. Unlike the laser modified section 36, the semiconductor element information formation area 48 is irradiated with laser only in the area where the semiconductor element information is to be printed. This reduces the number of laser irradiation pulses, thereby shortening the laser irradiation time.

[0050] 12 and 13 are plan views showing a semiconductor element information formation area according to embodiment 10. FIG. 12 shows a case where a two-dimensional code is represented by a laser modified portion 36. That is, the two-dimensional code is represented by the laser modified portion 36 shown in black and the third metal film 24 shown in white. FIG. 13 shows a case where a two-dimensional code is represented in an area not irradiated with laser. That is, the two-dimensional code is represented by the laser modified portion 36 shown in white and the third metal film 24 shown in black. In either case, by printing semiconductor element information by laser irradiation, it is possible to improve the traceability of the semiconductor element.

[0051] In addition to the semiconductor element information, for example, a mark indicating the position information of the semiconductor element can be printed. In this case, the position information of the semiconductor element can be recognized on the equipment side during the assembly process of the semiconductor device, which is expected to improve the visibility of the semiconductor element and the ease of assembly of the semiconductor device.

[0052] Embodiment 11 14 is a plan view showing a semiconductor device according to embodiment 11. Embodiment 11 differs from the previous embodiments in that laser irradiation is performed in a striped pattern.

[0053] In the semiconductor device according to the first embodiment, the surface electrode solder joint 6 is continuous, which poses a problem of thermal stress occurring at the solder joint interface. In this embodiment, the laser irradiation is performed in a striped pattern, as in the laser modified area 36c, to divide the solder joint interface into multiple parts. This allows the thermal stress occurring at the solder joint interface during a power cycle test to be dispersed.

[0054] 15 is a cross-sectional view showing a semiconductor device according to embodiment 11. By forming the laser-modified portions 36c in a striped pattern, voids 50 are formed below the surface electrode solder joints 6. In other words, because the interface of the solder joint is divided into multiple parts, it is possible to disperse the thermal stress that occurs during a power cycle test.

[0055] Embodiment 12 16 is a plan view showing a semiconductor device according to embodiment 12. Embodiment 12 differs from the previous embodiments in that laser irradiation is performed in a grid pattern.

[0056] In the semiconductor device according to the first embodiment, the surface electrode solder joint 6 is continuous, which poses a problem of thermal stress occurring at the solder joint interface. In this embodiment, the laser irradiation is performed in a grid pattern, as in the laser modified area 36d, to divide the solder joint interface into multiple parts. This allows the thermal stress occurring at the solder joint interface during a power cycle test to be dispersed.

[0057] Embodiment 13 17 is a plan view showing a semiconductor device according to embodiment 13. Embodiment 13 differs from the previous embodiments in that the laser irradiation is also performed on front surface electrode wire pad portions 8.

[0058] In the semiconductor device according to the first embodiment, when solder bonding is performed in the assembly process of the semiconductor element 2, solder may splash onto the front surface electrode wire pad portion 8. This causes a problem of poor aluminum wire bonding when subsequent bonding is performed using an aluminum wire or the like.

[0059] Therefore, in this embodiment, a laser is irradiated onto the surface of the front surface electrode wire pad portion 8 to form a laser modified portion 36e. As a result, even if solder splashes, it is possible to suppress solder wetting of the front surface electrode wire pad portion 8, which is expected to improve the yield in the assembly process.

[0060] Embodiment 14 18 is a cross-sectional view showing a semiconductor device before laser irradiation according to embodiment 14. Embodiment 14 differs from the previous embodiments in that laser irradiation is also performed on the back electrode.

[0061] The semiconductor element according to the fourteenth embodiment includes a back electrode 52. The back electrode 52 includes a fourth metal film 54 and a fifth metal film 56. In an assembly process, the back electrode 52 is soldered to a heat sink made of a conductive material such as Cu. As a result, a soldered region is formed along the shape of the back electrode 52.

[0062] Consider a case where the semiconductor device described above is subjected to a thermal cycle test in which thermal stress is applied. In this case, due to the difference in the linear expansion coefficients of the materials, thermal stress concentrates on the back electrode and the solder joint area, causing the corners of the solder joint area to peel off. This causes cracks in the solder, which can lead to the problem of semiconductor device degradation. Therefore, in this embodiment, the back electrode 52 is also irradiated with laser light.

[0063] 19 is a cross-sectional view showing a resin-sealed semiconductor device according to embodiment 14. Here, the semiconductor device is shown after solder bonding and resin sealing are performed on the front electrode side and the back electrode side.

[0064] When a laser is irradiated onto a portion of the back electrode side, a laser-modified portion 36f is formed on the surface layer of the fourth metal film 54. Solder bonding is then performed, but the solder 38 does not wet and spread onto the laser-modified portion 36f. On the other hand, the solder 38 wets and spreads onto the portions other than the laser-modified portion 36f, so solder bonding is performed. At this time, an intermetallic compound layer 58 is formed. When resin sealing is then performed, the laser-modified portion 36f is covered with the resin sealing material 42.

[0065] FIG. 20 is a plan view showing the back surface electrode before laser irradiation according to the fourteenth embodiment. FIG. 21 is a plan view showing the back surface electrode after laser irradiation according to the fourteenth embodiment. When forming the laser modified portion 36f, laser irradiation is performed so that the corners of the unirradiated portion are rounded. This unirradiated portion becomes the solder joint region 55. This makes it possible to distribute the stress acting on the corners of the solder joint region and prevent peeling of the corners.

[0066] Although the example shown here is one in which laser irradiation is performed so that the corners of the unirradiated portions of the back electrode are rounded, laser irradiation may also be performed so that the corners of the unirradiated portions of other regions are rounded.

[0067] Embodiment 15 The fifteenth embodiment differs from the previous embodiments in that a laser is irradiated onto the outermost periphery of the semiconductor substrate 30. In the semiconductor device according to the first embodiment, when thermal stress such as thermal cycling is applied, shear stress is applied from the resin encapsulant 42 to the outermost periphery of the semiconductor element 2. This causes a problem of peeling at the interface between the resin encapsulant 42 and the semiconductor element 2.

[0068] Therefore, in this embodiment, a laser is irradiated onto the outermost periphery of the semiconductor substrate 30. This increases the interfacial adhesion strength between the resin sealing material 42 and the semiconductor substrate 30, thereby improving the reliability of the semiconductor device.

[0069] 22 is a cross-sectional view showing an end portion of a semiconductor element before resin sealing according to embodiment 15. An oxide film 34 is formed on a semiconductor substrate 30. The oxide film 34 is covered with an overcoat film 60. The overcoat film 60 is covered with a coating film 28.

[0070] Laser-modified portion 36g is formed by laser irradiation on the outermost periphery of semiconductor substrate 30. Covering film 28 does not cover the outermost periphery of semiconductor element 2. Therefore, in the subsequent resin sealing process, the effect of laser-modified portion 36g increases the interfacial adhesion strength between resin sealing material 42 and semiconductor substrate 30.

[0071] 23 is a plan view showing a semiconductor element before resin encapsulation according to embodiment 15. Laser modified portion 36g is formed all over the outermost periphery of semiconductor element 2. This makes it possible to increase the interfacial adhesion strength between resin encapsulant 42 and semiconductor substrate 30.

[0072] Embodiment 16 FIG. 24 is a plan view showing a semiconductor element before resin encapsulation according to a sixteenth embodiment. The sixteenth embodiment differs from the previous embodiments in that a laser is irradiated onto the corners of the semiconductor substrate 30. The shear stress described in the fifteenth embodiment is concentrated at the corners of the semiconductor element. Therefore, in this embodiment, a laser is irradiated onto the corners of the semiconductor substrate 30. That is, a laser-modified portion 36h is formed at the corner of the semiconductor substrate 30. This locally increases the interfacial adhesion strength between the resin encapsulant 42 and the semiconductor substrate 30, thereby improving the reliability of the semiconductor device.

[0073] Embodiment 17 The seventeenth embodiment differs from the previous embodiments in that the semiconductor substrate 30 is made of silicon carbide.

[0074] Silicon is currently the most widely used material for semiconductor substrates. Compared to silicon substrates, silicon carbide has a longitudinal elastic modulus 2.6 times larger and a linear expansion coefficient 1.5 times larger, and its adhesion strength with resin encapsulation is less than two-thirds that of silicon substrates. Therefore, when power cycle tests are conducted on conventional semiconductor devices using silicon carbide substrates, interfacial peeling easily occurs between the encapsulation material and the semiconductor element surface. This poses a problem of reduced reliability for the semiconductor device.

[0075] However, in the semiconductor device according to the present disclosure, the surface roughening treatment by laser modification is expected to improve the adhesion between the encapsulant and the semiconductor element surface, and therefore, even when a silicon carbide substrate is used, high reliability of the semiconductor device can be expected.

[0076] In conventional semiconductor devices, a coating film such as a polyimide film is used as the stress buffer layer, and therefore the width of the stress buffer layer must be determined taking into account not only material-specific characteristics such as viscosity and photosensitivity, but also precision variations due to the coating device, such as coating position, air pressure, and coating amount.

[0077] However, in the semiconductor device according to the first embodiment, the dimensions of the processing area can be determined by considering only the laser processing accuracy. That is, processing variations can be reduced compared to conventional semiconductor devices. Therefore, by using expensive silicon carbide for the semiconductor substrate of the present disclosure, it is expected that the cost of semiconductor devices will be lower than conventional ones.

[0078] Although the present embodiment shows a case where the semiconductor substrate is made of silicon carbide, it may also be made of a wide bandgap semiconductor, which has a wide bandgap like silicon carbide. Examples of wide bandgap semiconductors include gallium nitride-based materials and diamond. [Explanation of symbols]

[0079] 2. Semiconductor elements 4 Back electrode 6 Surface electrode solder joint 8. Surface electrode wire pad 16 Encapsulating material 18 Laser Modification Section 26 Laser Light 27 Processing area 28 Coating membrane 34 Oxide film 36 Laser modification section 36a Laser modification section 36b Laser modification section 36c Laser modification section 36d Laser modification section 36e Laser modification section 36f Laser modification section 36g Laser modified part 36h Laser modified part 37 Solder joint area 42 Resin sealing material 44 Invalid Cell Area 46 Barrier metal layer 48 Semiconductor device information formation area 52 Back electrode 55 Solder joint area 100 Semiconductor device

Claims

1. A semiconductor device comprising a surface electrode solder joint, a solder, a resin sealing material, and a semiconductor element mounted below the surface electrode solder joint, The surface electrode solder joint is a first laser-modified portion having an outermost surface that is oxidized and roughened; a first solder joint area joined with the solder; The laser modified portion is Covered with the resin sealing material, It is formed by irradiating pulsed laser light, The processing area, which is an area that can be processed by one pulse irradiation, is arranged in a plurality of locations so as to surround the outer periphery of the surface electrode solder joint. Semiconductor device.

2. The processing areas are arranged at regular intervals so that adjacent ones overlap each other. The semiconductor device according to claim 1 .

3. A semiconductor device comprising a surface electrode solder joint, a solder, a resin sealing material, and a semiconductor element mounted below the surface electrode solder joint, The surface electrode solder joint is a first laser-modified portion having an outermost surface that is oxidized and roughened; a first solder joint area joined with the solder; The laser modified portion is Covered with the resin sealing material, The degree of oxidation and roughening is smaller in the region farther from the outermost periphery of the surface electrode solder joint than in the region closer to the outermost periphery. Semiconductor device.

4. A semiconductor device comprising a surface electrode solder joint, a solder, a resin sealing material, and a semiconductor element mounted below the surface electrode solder joint, The surface electrode solder joint is a first laser-modified portion having an outermost surface that is oxidized and roughened; a first solder joint area joined with the solder; the laser modified portion is covered with the resin sealing material, The semiconductor device has an active cell region that has functionality and an inactive cell region that does not have functionality, The ineffective cell region is located directly below the first laser-modified portion. Semiconductor device.

5. A semiconductor device comprising a surface electrode solder joint, a solder, a resin sealing material, and a semiconductor element mounted below the surface electrode solder joint, The surface electrode solder joint is a first laser-modified portion having an outermost surface that is oxidized and roughened; a first solder joint area joined with the solder; The laser modified portion is Covered with the resin sealing material, A semiconductor device information forming area in which a desired code is embedded is provided. Semiconductor device.

6. A semiconductor device comprising a surface electrode solder joint, a solder, a resin sealing material, and a semiconductor element mounted below the surface electrode solder joint, The surface electrode solder joint is a first laser-modified portion having an outermost surface that is oxidized and roughened; a first solder joint area joined with the solder; the laser modified portion is covered with the resin sealing material, The first solder joint region is divided into a plurality of regions. Semiconductor device.

7. The semiconductor device according to claim 6 , wherein the first laser-modified portion is formed in a striped pattern on a surface layer of the surface electrode solder joint portion.

8. The semiconductor device according to claim 6 , wherein the first laser-modified portion is formed in a lattice pattern on a surface layer of the surface electrode solder joint portion.

9. A semiconductor device comprising a surface electrode solder joint, solder, a resin sealing material, a semiconductor element mounted below the surface electrode solder joint, and a back electrode, The surface electrode solder joint is a first laser-modified portion having an outermost surface that is oxidized and roughened; a first solder joint area joined with the solder; the laser modified portion is covered with the resin sealing material, The rear electrode is a third laser-modified portion whose outermost surface is oxidized and roughened; a second solder joint area joined with the solder; The corners of the solder joint area are rounded. Semiconductor device.

10. A method for manufacturing a semiconductor device including a surface electrode solder joint, a solder, and a resin sealing material, comprising: forming a laser modified portion by irradiating a part of the surface electrode solder joint with pulsed laser light; a step of performing solder bonding on the surface electrode solder joint portion; a step of resin sealing using the resin sealing material so as to cover the laser modified portion; Equipped with The laser modified portion is formed by arranging a plurality of processing regions, which are regions that can be processed by one pulse irradiation, so as to surround the outer periphery of the surface electrode solder joint portion. A method for manufacturing a semiconductor device.

11. A method for manufacturing a semiconductor device including a surface electrode solder joint, a solder, and a resin sealing material, comprising: forming a laser modified portion by irradiating a part of the surface electrode solder joint with pulsed laser light; a step of performing solder bonding on the surface electrode solder joint portion; a step of resin sealing using the resin sealing material so as to cover the laser modified portion; Equipped with The step of forming the laser modified portion is realized by irradiating a region far from the outermost periphery of the surface electrode solder joint with pulsed laser light having a lower energy density than a region close to the outermost periphery. A method for manufacturing a semiconductor device.

12. A method for manufacturing a semiconductor device including a surface electrode solder joint, a solder, a resin sealing material, and a semiconductor element mounted below the surface electrode solder joint, the method comprising: forming a laser modified portion by irradiating a part of the surface electrode solder joint with pulsed laser light; a step of performing solder bonding on the surface electrode solder joint portion; a step of resin sealing using the resin sealing material so as to cover the laser modified portion; Equipped with The semiconductor device has an active cell region that has functionality and an inactive cell region that does not have functionality, The ineffective cell region is formed so as to be located directly below the laser modified portion. A method for manufacturing a semiconductor device.

13. A method for manufacturing a semiconductor device including a surface electrode solder joint, a solder, and a resin sealing material, comprising: forming a laser modified portion by irradiating a part of the surface electrode solder joint with pulsed laser light; a step of performing solder bonding on the surface electrode solder joint portion; a step of resin sealing using the resin sealing material so as to cover the laser modified portion; Equipped with The step of forming the laser modified portion includes a step of irradiating the semiconductor device with pulsed laser light to form a semiconductor device information forming area that forms a desired code. A method for manufacturing a semiconductor device.

14. A method for manufacturing a semiconductor device including a surface electrode solder joint, a solder, and a resin sealing material, comprising: forming a laser modified portion by irradiating a part of the surface electrode solder joint with pulsed laser light; a step of performing solder bonding on the surface electrode solder joint portion; a step of resin sealing using the resin sealing material so as to cover the laser modified portion; Equipped with The surface electrode solder joint portion has a first solder joint region that is joined with the solder and is divided into a plurality of regions. A method for manufacturing a semiconductor device.

15. A method for manufacturing a semiconductor device including a surface electrode solder joint, a solder, a resin sealing material, and a back surface electrode, the method comprising: forming a laser modified portion by irradiating a part of the surface electrode solder joint with pulsed laser light; a step of performing solder bonding on the surface electrode solder joint portion; a step of resin sealing using the resin sealing material so as to cover the laser modified portion; a step of irradiating the outermost surface of the back electrode with a laser; a step of irradiating the back electrode with a laser so that the corners of the second solder joint region, which is the region of the back electrode joined with the solder, are rounded; A method for manufacturing a semiconductor device comprising:

16. the surface electrode solder joint has an upper metal film and a lower metal film, The lower metal film has a higher laser light absorption rate than the upper metal film. The method for manufacturing a semiconductor device according to any one of claims 10 to 15.

17. the surface electrode solder joint has an upper metal film and a lower metal film, the thickness of the lower metal film is 1 μm or more, The thickness of the upper metal film is 0.2 μm or less. The method for manufacturing a semiconductor device according to any one of claims 10 to 15.

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