JP5830958B2 - Semiconductor module - Google Patents

Description

  The present invention relates to a semiconductor module mounted with an unevenness formed between a semiconductor chip and a mounting substrate.

  Conventionally, a technique in which excessive solder flows into the submount through the submount narrow groove and is discharged to the outside through the extension groove when soldering the semiconductor laser element is described in, for example, the following documents ( Patent Document 1). By adopting such a technique, it is possible to prevent the spherical bonding material residue from being formed on the semiconductor laser element, the submount, or the heat sink when the semiconductor laser assembly is manufactured.

International Publication No. WO2004 / 077630

  In the semiconductor element mounting technology as described above, a countermeasure for heat generation has become an important issue as the power consumption of the semiconductor element increases. In a semiconductor element that generates heat during operation, a rise in temperature causes destruction of the semiconductor element. Therefore, it is necessary to improve the cooling performance by reducing the thermal resistance of the heat transfer path. When a semiconductor chip is mounted on a mounting substrate via a bonding material such as solder, the bonding material has a lower thermal conductivity than the mounting substrate, so bonding is necessary to reduce the thermal resistance of the heat transfer path. Thinning the material is effective.

  On the other hand, the bonding material has an effect of relieving thermal stress generated due to a difference in linear expansion coefficient between the semiconductor chip and the mounting substrate. Accordingly, in order to ensure long-term reliability in consideration of repeated thermal stress due to temperature changes during use, the bonding material needs to have an appropriate thickness.

  In the conventional mounting structure, when the bonding material is thinned in order to reduce the thermal resistance, the plane portions on the side where the semiconductor chip and the mounting base material face each other are close to each other. For this reason, stress concentration due to thermal stress is prominently generated in the vicinity of the semiconductor chip and the mounting substrate, and the long-term reliability of the bonding material is lowered. Therefore, it has been difficult for the conventional mounting structure to achieve both improved cooling performance and long-term reliability.

  Therefore, the present invention has been made in view of the above, and the object of the present invention is to satisfy both improvement of cooling performance and securing of long-term reliability when a semiconductor chip is mounted on a mounting substrate. An object of the present invention is to provide a semiconductor module.

  In order to achieve the above object, the present invention straddles the end of the bonding surface between the electrode portion of the semiconductor chip and the mounting substrate when the semiconductor chip and the mounting substrate are bonded via the bonding material. Thus, the mounting substrate and the semiconductor chip are closest to each other at the apex of the protrusion.

  According to the present invention, the unevenness is arranged and formed so as to straddle the end portion of the bonding surface between the electrode portion of the semiconductor chip and the mounting substrate, so that the thickness of the bonding material can be reduced to reduce the thermal resistance. This makes it possible to improve the cooling performance. In addition, it is possible to reduce the area of the proximity portion between the semiconductor chip and the mounting substrate to alleviate the concentration of thermal stress, and to ensure long-term reliability.

It is sectional drawing which shows the structure of the semiconductor module which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the example of a shape of the uneven | corrugated | grooved part shown in FIG. It is a figure which shows the example of arrangement | positioning of the uneven | corrugated | grooved part shown in FIG. It is a figure which shows the example of arrangement | positioning of the uneven | corrugated | grooved part shown in FIG. It is a top view which shows the example of arrangement | positioning of the uneven | corrugated | grooved part shown in FIG. 1 with respect to the mounting surface of a semiconductor chip. It is a top view which shows the example of arrangement | positioning of the uneven | corrugated | grooved part shown in FIG. 1 with respect to the mounting surface of a semiconductor chip. It is a top view which shows the example of arrangement | positioning of the uneven | corrugated | grooved part shown in FIG. 1 with respect to the mounting surface of a semiconductor chip. It is sectional drawing which shows the structure of the semiconductor module which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the semiconductor module which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the uneven | corrugated member shape example shown in FIG. It is a figure which shows the example of arrangement | positioning of the uneven | corrugated member shown in FIG. It is a figure which shows the example of arrangement | positioning of the uneven | corrugated member shown in FIG. It is sectional drawing which shows the structure of the semiconductor module which concerns on Embodiment 4 of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
1A and 1B are diagrams showing a configuration of a semiconductor module according to Embodiment 1 of the present invention, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view.

  In FIG. 1, a semiconductor chip 11 is mounted by being bonded to a mounting substrate 13 via a bonding material 12, thereby forming a semiconductor module. In the semiconductor module, an arbitrary portion is covered with an insulating layer in order to ensure a creepage distance and a spatial distance against discharge and to maintain long-term reliability when a voltage is applied. The semiconductor chip 11 is configured by a power conversion power module such as an inverter circuit that supplies power to a motor that drives a vehicle, for example, and is configured by a power semiconductor device rated at several hundred volts and several hundred amperes, for example. In general, the power module uses two types of semiconductor elements, a diode and a switching element, and the present invention is applicable to both semiconductor chips. The semiconductor chip 11 has a thickness of about 100 micrometers, for example, and a vertical and horizontal size of about several millimeters. As the semiconductor chip 11, for example, a wide range of semiconductor chips can be used regardless of the semiconductor substrate material such as Si, SiC, GaN, organic type, and the degree of integration.

  In the first embodiment, the bonding material 12 is made of solder. The bonding material 12 can be appropriately selected from an inorganic or organic bonding material capable of conducting heat that does not cause performance deterioration such as heat resistance and electrical characteristics of the semiconductor chip 11 or a bonding material obtained by combining them. is there. Moreover, as a characteristic of the bonding material 12, a bonding material that is hardened or softened under certain conditions such as heat, electromagnetic waves, and vibrations is desirable.

  Furthermore, the joining material 12 can select the joining material and joining method suitable for each joining location. For example, it differs from the selection of a bonding material having a different composition between the center and outer periphery of the bonding portion between the semiconductor chip 11 and the mounting substrate 13, or the uneven portion 131 and the flat portion, metal bonding, chemical bonding, physical bonding, composite bonding, and the like. Selection of joining method is possible.

  In the first embodiment, the mounting substrate 13 is made of a Cu (copper) material that is excellent in thermal conductivity and electrical conductivity. For the mounting substrate 13, it is possible to use, for example, inorganic and organic materials capable of conducting heat or composite materials thereof other than Cu.

  The size of the mounting substrate 13 varies depending on the heat resistance of the semiconductor chip 11. For example, when the heat generation amount of the semiconductor chip 11 is large or the heat resistance of the heat transfer path is large, the mounting substrate 13 can be enlarged. In the first embodiment, for example, one side has a size of several millimeters to several tens of millimeters. Depending on the characteristics of the semiconductor chip 11, it is possible to use a mounting substrate 13 smaller than the area of the semiconductor chip 11. That is, it is possible to select and combine the sizes of the semiconductor chip 11 and the mounting substrate 13 regardless of the size relationship between the semiconductor chip 11 and the mounting substrate 13.

  When the mounting substrate 13 is used as a current path of the semiconductor chip 11, it is possible to select inorganic and organic materials that can conduct heat and have conductivity, or composite materials thereof. For example, a simple metal such as Cu, Al, Mo, or W, or an alloy or composite material thereof can be used. Moreover, it is possible to use epoxy-type, acrylic-type, imide-type, etc. resins and ceramics, composite materials of these resins and conductors or insulators, or composite materials in which these metals, resins, ceramics, etc. are laminated. .

  On the mounting substrate 13, an uneven portion 131 is formed on the mounting surface on the side where the semiconductor chip 11 is mounted facing the semiconductor chip 11. The concavo-convex portion 131 is disposed and formed so as to straddle at least the end portion of the bonding surface where the electrode portion of the semiconductor chip 11 and the mounting base material 13 are electrically bonded via the bonding material 12. Here, the electrode portion of the semiconductor chip is, for example, a gate terminal, a source terminal, a drain terminal, or the like of a transistor that constitutes a switching element, such as an anode terminal or a cathode terminal of a diode.

  FIG. 2 shows an example of the cross-sectional shape of the uneven portion 131. 2A, the projection 1311 has a pyramidal cross section, FIG. 2B shows the tip of the projection 1312 having a conical tip, and FIG. 2C shows the tip of the projection 1313. The part shows an example of a gable. A feature of the cross-sectional shape of the concavo-convex portion 131 is that the convex portion is inclined with respect to the bonding surface of the semiconductor chip 11. Due to this inclination, after the semiconductor chip 11 and the mounting substrate 13 are joined, the proximity portion between the semiconductor chip 11 and the concavo-convex portion 131 becomes a dot or a line.

  As mentioned above, since the bonding material 12 has an effect of relieving the thermal stress between the semiconductor chip 11 and the mounting substrate 13, the bonding material 12 needs to have an appropriate thickness. Temporarily, when there is no uneven part 131, the proximity part after joining of semiconductor chip 11 and mounting substrate 13 becomes a plane. For this reason, stress concentration due to thermal stress occurs remarkably in the vicinity of the semiconductor chip 11 and the mounting substrate 13, and the long-term reliability of the bonding material 12 is reduced. In contrast, by providing the mounting substrate 13 with the concavo-convex portion 131, the area of the proximity portion between the semiconductor chip 11 and the mounting substrate 13 is reduced as compared with the case where it is not provided. Thereby, generation | occurrence | production of stress concentration can be suppressed.

  The shape of the uneven portion 131 shown in FIG. 1 is a quadrangular pyramid shape as shown in FIG. By adopting the quadrangular pyramid shape, the area of the proximate part between the convex part of the concave-convex part 131 and the semiconductor chip 11 becomes very small. Thereby, it is possible to suppress the occurrence of stress concentration due to thermal stress. The internal angle of the concavo-convex portion 131 shown in FIG. 1 is about 60 degrees, but by using a sharper shape or a triangular pyramid, the stress concentration due to thermal stress can be easily dispersed, and long-term reliability is further improved. It becomes possible.

  In the cross-sectional shape shown in FIG. 2B, the tip of the convex portion is a curved surface. For this reason, even when the semiconductor chip 11 and the mounting base material 13 are pressed and bonded during the mounting process, stress concentration due to pressing is suppressed compared to the cross-sectional shapes shown in FIGS. Therefore, there is little deformation of the uneven shape, and the solder thickness can be kept constant.

  Moreover, it is also possible to mix the said cross-sectional shape. For example, the cross-sectional shape of FIG. 2A is used in a portion where the stress concentration is large when thermal stress is generated, and the cross-sectional shape of FIG. As a result, it is possible to further improve the long-term reliability and the improvement of the cooling performance as compared with the case where they are not mixed.

  The height of the uneven portion 131 of the mounting substrate 13 is, for example, about several tens to several hundreds of micrometers. The height of the concavo-convex portion 131 is determined in consideration of the physical properties of the bonding material 12 and the mounting substrate 13, the actual use temperature of the semiconductor module, and the cycle thereof. That is, it is desirable that the thermal stress generated in the vicinity of the bonding material 12 and the concavo-convex portion 131 can be suppressed to a target fatigue limit or less.

  Further, the height of the concavo-convex portion 131 is not the same for all the concavo-convex portions 131, and a plurality of heights can be used according to the bonding material 12 to be used and the state of occurrence of stress concentration due to thermal stress.

For example, the center of the joint between the semiconductor chip 11 and the mounting substrate 13 is made higher than the outer periphery, and vice versa.

  3A (a1), (a2) to FIG. 3 (d1), (d2), and FIG. 3B (e1). , (E2) to (h1), (h2) are possible. 3A (a2) to FIG. 3B (h2) are cross-sectional views taken along the broken lines in FIG. 3A (a1) to FIG. 3B (h1). In FIG. 3A (a1) and (a2), the conical convex part 1312 is discretely arrange | positioned at the grid | lattice form. In FIGS. 3A (b1) and (b2), the conical convex portions 1312 are discretely arranged in a lattice pattern alternately. 3A (c1) and (c2), triangular pyramid convex portions 1311 having different heights are in contact with each other and arranged in a lattice pattern. In FIG. 3A (d1) and (d2), the convex portions 1311 of the quadrangular pyramids are in contact with each other and arranged in a lattice shape.

  On the other hand, in FIG. 3B (e1) and (e2), a plurality of ridge-shaped (kamaboko-shaped) convex portions 1314 are arranged in parallel. In FIG. 3B (f1) and (f2), the hook-shaped convex parts 1314 are alternately arranged discretely. In FIG. 3B (g1) and (g2), the saddle-shaped convex portions 1314 in adjacent rows are discretely arranged so that the directions of the proximity portions to the semiconductor chip 11 are different. In FIG. 3B (h1) and (h2), the hook-shaped convex portions 1314 are arranged in a lattice pattern.

  As described above, the uneven portion 131 of the mounting substrate 13 is disposed across the end portion of the bonding surface between the electrode portion of the semiconductor chip 11 and the mounting substrate 13. Thereby, at the time of mounting, the excessive bonding material 12 under the low viscosity condition is continuously guided from the bottom of the electrode portion of the semiconductor chip 11 to the outer periphery of the semiconductor chip 11 by the capillary phenomenon of the uneven portion 131. Therefore, it is avoided that the excessive bonding material 12 stays between the electrode portion of the semiconductor chip 11 and the mounting base material 13 and the bonding material 12 becomes thicker than necessary. As a result, it can suppress that cooling performance falls.

  4A (a) to 4C (j) are plan views illustrating an arrangement example of the uneven portion 131 with respect to the mounting surface of the semiconductor chip 11. FIG. As shown in FIG. 4A (a), by disposing the concavo-convex portion 131 on the mounting substrate 13 over the entire outer periphery of the semiconductor chip 11, the ability to suppress the cooling performance degradation can be increased.

  On the other hand, in FIG. 4A (b), uneven portions 131 are arranged at the four corners of the portion where the semiconductor chip 11 is arranged. The semiconductor chip 11 at the time of bonding is slightly inclined with respect to the bonding surface of the mounting base material 13 due to the contact state (wetting state) of the bonding material 12 to the mounting base material 13 and the surface tension of the bonding material 12. For this reason, the excess bonding material is likely to accumulate at the four corners of the semiconductor chip 11. Therefore, the thickness of the bonding material 12 becomes thicker than necessary, and the cooling performance tends to be lowered. 4A (b), the excess bonding material 12 at the four corners of the semiconductor chip 11 can be guided to the outer periphery of the semiconductor chip 11 by capillary action and discharged out of the semiconductor chip 11. As a result, the thickness of the bonding material 12 can be kept appropriate and uniform.

  In FIG. 4A (c), with respect to the arrangement of FIG. With such an arrangement, a proximity portion between the semiconductor chip 11 and the concavo-convex portion 131 having high thermal conductivity is provided in the central portion where the temperature in the semiconductor chip 11 is likely to rise as compared to FIG. 4A (b). It is done. As a result, the cooling performance can be further improved.

  In FIG. 4A (d), the concavo-convex portion 131 is arranged corresponding to each side portion excluding the four corners of the semiconductor chip 11. Stress on the bonding material 12 tends to concentrate at the four corners of the semiconductor chip 11. Therefore, by arranging as shown in FIG. 4A (d), the average thickness of the bonding material 12 at the four corners of the semiconductor chip 11 can be increased as compared with FIG. 4A (a). As a result, thermal stress is dispersed and long-term reliability can be further improved.

  4B (e) to FIG. 4 (h), the concavo-convex portion 131 disposed corresponding to the central portion of the semiconductor chip 11 is continuously disposed on the outer periphery of the semiconductor chip 11 without interruption. With such an arrangement, it is possible to reliably guide the excessive bonding material 12 in the central portion of the semiconductor chip 11 to the outer periphery and discharge it outside the semiconductor chip 11. As a result, it is possible to suppress a decrease in cooling performance. Moreover, since the proximity part of the uneven | corrugated | grooved part 131 with high heat conductivity and the semiconductor chip 11 can be provided in the center part of the semiconductor chip 11, it becomes possible to improve cooling performance.

  In FIG. 4C (i), the concavo-convex portion 131 is arranged over the entire bonding surface of the semiconductor chip 11. By setting it as such arrangement | positioning, the proximity | contact part of the semiconductor chip 11 and the mounting base material 13 increases compared with previous FIG. 4A (a). Thereby, the average thickness of the bonding material 12 can be reduced, and the cooling performance can be improved.

  In FIG. 4C (j), the uneven | corrugated | grooved part from which the uneven | corrugated shape differs in the example of arrangement | positioning shown to previous FIG. 4C (i) is arrange | positioned. For example, the first concavo-convex portion 131-1 having a convex body as shown in FIG. 2A is arranged on the outer peripheral portion of the semiconductor chip 11. On the other hand, a second concavo-convex portion 131-2 having a ridge shape as shown in FIGS. 3B (e1), (e2) to (h1), (h2) is disposed in the central portion of the semiconductor chip 11. .

  By adopting such an arrangement, the end of the semiconductor chip 11 where stress concentration is likely to occur in the bonding material 12 is formed into a weight-like body as shown in FIG. The area of the proximity portion can be reduced. This makes it possible to suppress long-term reliability by suppressing stress concentration. Further, the central portion of the semiconductor chip 11 that is likely to become high temperature due to heat generation of the semiconductor chip 11 is formed in a bowl shape shown in FIG. 3B, whereby the average thickness of the bonding material 12 can be reduced and the thermal resistance can be reduced. As a result, it is possible to improve the cooling performance.

  In consideration of stable bonding of the semiconductor chip 11, the number of convex vertices of the concavo-convex portion 131 of the mounting substrate 13 is desirably three or more on the bonding surface between the semiconductor chip 11 and the concavo-convex portion 131. Thereby, the thickness of the bonding material 12 can be kept constant, the generation of an extreme stress concentration portion can be prevented, and long-term reliability can be ensured.

  In addition, the proportion of the bonding material 12 on the bonding surface increases as the distance between the apexes of the uneven portion 131 increases. For this reason, the cooling performance is deteriorated by the bonding material 12 having a large thermal resistance. Therefore, the distance between the vertices of the concavo-convex portion 131 is desirably equal to or less than the height of the convex portion in the concavo-convex portion 131.

As a result, it is possible to secure the heat transfer path and the diffusion portion and reduce the average thickness of the bonding material 12 to improve the cooling performance. The distance between the vertices of the concavo-convex portion 131 can be implemented, for example, in the order of several tens to several hundreds of micrometers.

  The distance between the vertices of the concavo-convex portion 131 can be mixed within a range of the distance between the vertices when using different types of the bonding material 12 or controlling the fluidity of the bonding material 12. Moreover, when the solid additive etc. are mixed in the joining material 12, the said requirements can be changed for the distance between the vertexes of the uneven | corrugated | grooved part 131, and the height of a convex part according to the mixed additive. . That is, the bonding material 12 containing the mixed additive is changed to such an extent that it is guided to the outer peripheral portion of the semiconductor chip 11 through the uneven portion 131 and discharged out of the semiconductor chip 11.

  In the mounting example shown in FIG. 1, the case where the semiconductor chip 11 and the convex portion vertex of the concave and convex portion 131 of the mounting substrate 13 are in contact with each other is illustrated, but it is not always necessary to be in contact. That is, as long as the specification performance of each part, such as the cooling performance, is not impaired, the two may not be in direct contact with each other and the bonding material 12 may be interposed therebetween.

  In the first embodiment, the uneven portion 131 is formed on the mounting base material 13. However, for example, when the semiconductor chip 11 is larger than the mounting base material 13, the same uneven portion as that provided on the mounting base material 13. It is also possible to provide 131 on the semiconductor chip 11 side instead of the mounting substrate 13. Even if it is such a structure, the effect similar to the case where it provides in the mounting base material 13 can be acquired.

  The cooling performance of the semiconductor module depends on the magnitude of the thermal resistance of the heat transfer path, and is improved by thinning the bonding material 12 having a lower thermal conductivity than the mounting substrate 13. In the first embodiment, the uneven portion 131 is provided so as to straddle the electrode portion of the semiconductor chip 11 and the end portion of the joint surface of the mounting substrate 13. Thereby, the bonding material 12 under the semiconductor chip 11 flows out to the concavo-convex portion 131 on the outer periphery of the semiconductor chip 11 due to a capillary phenomenon, and the thickness of the bonding material 12 under the semiconductor chip 11 decreases. In addition, the average thickness of the bonding material 12 is reduced by the proximity of the convex portion and the semiconductor chip 11, and the cooling performance can be improved by reducing the thermal resistance.

  The long-term reliability of a semiconductor module is determined by the difference in linear expansion coefficient between different types of joints, the amount of stress concentration when thermal stress is generated, and the yield strength of each member. In the first embodiment, since the area and distance of the parallel surface where the semiconductor chip 11 and the mounting substrate 13 are close to each other (the thickness of the bonding material 12) are determined, long-term reliability is improved by reducing the area of the parallel surface and increasing the distance. Can be improved. Since the convex portion of the concavo-convex portion 131 is inclined with respect to the semiconductor chip 11, the area of the parallel surface between the semiconductor chip 11 and the proximate portion of the convex vertex is minimized, and long-term reliability can be ensured.

  When the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in a dot shape or a line shape, the area of the parallel surface of the proximity portion is minimized. Further, since the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in at least one point or a line shape, the minimum thickness necessary for the bonding material 12 in the concave portion of the concavo-convex portion 131 is ensured. It is possible to ensure the sex.

  Since the bonding material 12 is not used for the bonding portion of the semiconductor chip 11 and the concavo-convex portion 131 and a direct bonding in which each material diffuses is used, a portion where no bonding material having a high thermal resistance is present is generated. It is possible to reduce the average thickness and improve the cooling performance.

  By arranging and forming the uneven portion 131 on the whole or a part of the outer periphery of the bonding surface between the semiconductor chip 11 and the mounting substrate 13, it becomes possible to discharge the excess bonding material 12 outside the semiconductor chip 11. It is possible to keep the thickness of the material 12 properly and to suppress a decrease in cooling performance.

(Embodiment 2)
FIG. 5 is a cross-sectional view showing a configuration of a semiconductor module according to Embodiment 2 of the present invention. The second embodiment is different from the first embodiment in that the semiconductor chip 11 is provided with the uneven portion 111. In the configuration shown in FIG. 5A, the uneven portion 111 is provided on the joint surface of the semiconductor chip 11 with the mounting substrate 13, and the uneven portion similar to that of the first embodiment is formed on the outer peripheral mounting substrate 13 of the semiconductor chip 11. 131 is provided.

With such a configuration, it becomes possible to reduce the average thickness of the bonding material 12 and reduce the thermal resistance, and as a result, the cooling performance can be improved. In addition, the heat capacity of the semiconductor chip 11 is increased by the concavo-convex portion 111, so that heat can be diffused and transmitted quickly with respect to the transient heat generation of the semiconductor chip 11. As a result, it is possible to prevent thermal destruction of the semiconductor chip 11 due to transient heat generation.
In the configuration shown in FIG. 5B, an uneven portion 131 is added to the bonding surface of the mounting substrate 13 facing the central portion of the semiconductor chip 11 with respect to the configuration shown in FIG. . With such a configuration, it becomes possible to further reduce the average thickness of the bonding material 12 to reduce the thermal resistance with respect to the effect obtained in the configuration of FIG. The cooling performance can be further improved.

  The cooling performance of the semiconductor module depends on the magnitude of the thermal resistance of the heat transfer path, and is improved by thinning the bonding material 12 having a lower thermal conductivity than the mounting substrate 13. In the first embodiment, the uneven portion 131 is provided so as to straddle the electrode portion of the semiconductor chip 11 and the end portion of the joint surface of the mounting substrate 13. Thereby, the bonding material 12 under the semiconductor chip 11 flows out to the concavo-convex portion 131 on the outer periphery of the semiconductor chip 11 due to a capillary phenomenon, and the thickness of the bonding material 12 under the semiconductor chip 11 decreases. In addition, the average thickness of the bonding material 12 is reduced by the proximity of the convex portion and the semiconductor chip 11, and the cooling performance can be improved by reducing the thermal resistance.

  The long-term reliability of a semiconductor module is determined by the difference in linear expansion coefficient between different types of joints, the amount of stress concentration when thermal stress is generated, and the yield strength of each member. In the second embodiment, since the area and distance of the parallel surface where the semiconductor chip 11 and the mounting substrate 13 are close to each other (the thickness of the bonding material 12) are determined, long-term reliability is improved by reducing the area of the parallel surface and increasing the distance. Can be improved. Since the convex portion of the concavo-convex portion 131 is inclined with respect to the semiconductor chip 11, the area of the parallel surface between the semiconductor chip 11 and the proximate portion of the convex vertex is minimized, and long-term reliability can be ensured.

  When the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in a dot shape or a line shape, the area of the parallel surface of the proximity portion is minimized. Further, since the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in at least one point or a line, the minimum thickness necessary for the bonding material 12 in the concave portion of the concavo-convex portion 131 is ensured. It is possible to ensure the sex.

  Since the bonding material 12 is not used at the bonding portion between the semiconductor chip 11 and the concavo-convex portion 131 and a direct bonding in which each material diffuses is used, a portion where no bonding material having a high thermal resistance is present is generated. It is possible to reduce the average thickness of the material and improve the cooling performance.

  By arranging and forming the uneven portion 131 on the whole or a part of the outer periphery of the bonding surface between the semiconductor chip 11 and the mounting substrate 13, it becomes possible to discharge the excess bonding material 12 outside the semiconductor chip 11. It is possible to keep the thickness of the material 12 properly and to suppress a decrease in cooling performance.

(Embodiment 3)
FIG. 6 is a cross-sectional view showing a configuration of a semiconductor module according to Embodiment 3 of the present invention. FIG. 6A is a cross-sectional view of each member before joining, and FIG. 6B is each member after joining. FIG.

  The third embodiment is different from the first and second embodiments in that the uneven portion 131 formed on the mounting substrate 13 and the uneven portion 111 formed on the semiconductor chip 11 are replaced with the semiconductor chip 11 and the mounting substrate 13. Is configured as a separate concavo-convex member 61.

  The material, size, and arrangement of the mounting substrate 13 and the concavo-convex member 61 and the method for joining the semiconductor chip 11, the concavo-convex member 61, and the mounting substrate 13 are the same as those in the first embodiment.

  The concavo-convex member 61 is formed of, for example, the same Cu as that of the mounting substrate 13 and is small and has a size of about several tens to several hundreds of micrometers. In the configuration shown in FIG. 6, the semiconductor chip 11 and the mounting substrate 13 are joined in the same manner as in FIG. 1 by interposing an uneven member 61 in which convex portions similar to those shown in FIG. 1 are formed in a pyramid shape. Have been implemented.

  As a configuration after joining, when the uneven member 61 has the same shape as that of the previous embodiment 1, the difference from the previous embodiment 1 is that the mounting substrate 13 and the uneven member are formed as shown in FIG. That is, the bonding material 12 is interposed between the member 61 and the member 61. As a result, the effect of suppressing stress concentration is increased as compared with the first embodiment, and long-term reliability can be further improved.

  In addition, when the difference of the linear expansion coefficient of the mounting base material 13 and the uneven | corrugated member 61 is small, the direct joining which a mutual material diffuses is also possible. In such a case, a portion where the bonding material 12 serving as thermal resistance does not exist is generated, so that the average thickness of the bonding material 12 is reduced and the cooling performance can be further improved.

  FIG. 7 shows an example of the cross-sectional shape of the concavo-convex member 61. 7A shows an example in which the convex portion 611 has a pyramidal cross section, FIG. 7B shows an example in which the convex portion 612 has a circular cross section, and FIG. 7C shows an example in which the convex portion 613 has a rhombic cross section. ing. 7D shows an example in which the cross section of the tip portion of the convex portion 614 is conical, and FIG. 7E shows an example in which the cross section of the tip portion of the convex portion 615 is gable.

  7 can be arranged with respect to the mounting substrate 13 as shown in FIGS. 8A (a1), (a2) to 8B (h1), (h2). 8A (a2) to FIG. 8B (h2) are cross-sectional views of FIG. 8A (a1) to FIG. 8B (h1). In FIGS. 8A (a1) and (a2), the spherical convex portions 612 are discretely arranged in a lattice shape in the cross-sectional shape shown in FIG. 7B. In FIGS. 8A (b1) and (b2), the convex portions 612 of the sphere are discretely arranged in a lattice pattern in a cross-sectional shape shown in FIG. 7B. In FIGS. 8A (c1) and (c2), the triangular pyramid convex portions 611 having different heights in the concavo-convex member 61 are arranged in a grid pattern. In FIGS. 8A (d1) and (d2), the convex portions 611 of the quadrangular pyramid shown in FIG.

  8B (e1) and (e2), a plurality of columnar convex portions 616 having the cross-sectional shape shown in FIG. 7B are arranged in parallel. 8B (f1) and (f2), the columnar convex portions 616 having the cross-sectional shape shown in FIG. 7B are arranged alternately and discretely. In FIGS. 8B (g1) and (g2), adjacent rows The convex portions 616 are discretely arranged so that the directions of the proximity portions to the semiconductor chip 11 are different. In FIG. 8B (h1) and (h2), cylindrical convex portions 616 having the cross-sectional shape shown in FIG. 7B are arranged in a lattice shape.

  Although not shown, in FIGS. 8B (e1) and (e2) to (h1) and (h2), instead of the cross-sectional convex portion shown in FIG. 7B, FIG. , (C) to (e) can be convex portions having a cross-sectional shape.

  In the cross-sectional shapes shown in FIGS. 7A, 7 </ b> D, and 7 </ b> E, the vertex of the convex portion is dotted on the joint surface between the semiconductor chip 11 and the concavo-convex member 61 where the difference in linear expansion coefficient is the largest and the thermal stress is generated. Or it becomes a structure which contacts or adjoins in a linear form. As a result, the stress concentration can be suppressed and the generation of thermal stress can be reduced. Further, the bonding surfaces of the mounting substrate 13 and the concavo-convex member 61 are close to each other so that the average thickness of the bonding material 12 can be reduced and the cooling performance can be improved.

  The cross-sectional shapes shown in FIGS. 7B and 7C have a structure in which the upper and lower surfaces of the concavo-convex member 61 are in contact with or close to each other by dots or lines. This makes it possible to further suppress stress concentration compared to the cross-sectional shapes shown in FIGS. 7A, 7D, and 7E, and to further improve long-term reliability.

  When manufacturing such a concavo-convex member 61, the concavo-convex member 61 is mounted on the mounting substrate 13 in advance before mounting, for example, using a female-shaped jig for aligning the plurality of concavo-convex members 61 in an arbitrary arrangement. It is also possible to join.

  The cooling performance of the semiconductor module depends on the magnitude of the thermal resistance of the heat transfer path, and is improved by thinning the bonding material 12 having a lower thermal conductivity than the mounting substrate 13. In the first embodiment, the uneven portion 131 is provided so as to straddle the electrode portion of the semiconductor chip 11 and the end portion of the joint surface of the mounting substrate 13. Thereby, the bonding material 12 under the semiconductor chip 11 flows out to the concavo-convex portion 131 on the outer periphery of the semiconductor chip 11 due to a capillary phenomenon, and the thickness of the bonding material 12 under the semiconductor chip 11 decreases. In addition, the average thickness of the bonding material 12 is reduced by the proximity of the convex portion and the semiconductor chip 11, and the cooling performance can be improved by reducing the thermal resistance.

  The long-term reliability of a semiconductor module is determined by the difference in linear expansion coefficient between different types of joints, the amount of stress concentration when thermal stress is generated, and the yield strength of each member. In the third embodiment, since the area and distance (the thickness of the bonding material 12) of the parallel surface where the semiconductor chip 11 and the mounting substrate 13 are close to each other are determined, long-term reliability is achieved by reducing the area of the parallel surface and increasing the distance. Can be improved. Since the convex portion of the concavo-convex portion 131 is inclined with respect to the semiconductor chip 11, the area of the parallel surface between the semiconductor chip 11 and the proximate portion of the convex vertex is minimized, and long-term reliability can be ensured.

  When the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in a dot shape or a line shape, the area of the parallel surface of the proximity portion is minimized. Furthermore, since the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in at least one or more points or lines, the minimum thickness necessary for the bonding material 12 in the concave portion of the concavo-convex portion 131 is ensured. It is possible to ensure the sex.

  By configuring the concavo-convex member 61 as a separate body from the semiconductor chip 11 and the mounting substrate 13, the number of layers capable of stress relaxation (the concavo-convex member 61) increases, and long-term reliability can be further improved.

  Since the bonding material 12 is not used at the bonding portion between the semiconductor chip 11 and the concavo-convex portion 131 and a direct bonding in which each material diffuses is used, a portion where no bonding material having a high thermal resistance is present is generated. It is possible to reduce the average thickness of the material and improve the cooling performance.

  By arranging and forming the uneven portion 131 on the whole or a part of the outer periphery of the bonding surface between the semiconductor chip 11 and the mounting substrate 13, it becomes possible to discharge the excess bonding material 12 outside the semiconductor chip 11. It is possible to keep the thickness of the material 12 properly and to suppress a decrease in cooling performance.

(Embodiment 4)
FIG. 9 is a cross-sectional view showing a configuration of a semiconductor module according to Embodiment 4 of the present invention.

  The feature of the fourth embodiment is that the surface of the semiconductor chip 11 opposite to the one surface (the lower surface in FIG. 1) of the semiconductor chip 11 on the side to which the mounting substrate 13 is bonded (the lower surface in FIG. 1). This is because the electrode materials 91 and 92 are joined to the upper surface in FIG. In addition, the uneven portion 112 similar to that of the second embodiment is formed on the surface of the semiconductor chip 11 on the side to be joined to the electrode material 92.

  The material, size and arrangement of the semiconductor chip 11, the uneven portion 112 of the semiconductor chip 11, the bonding material 12, the mounting base material 13, the uneven portion 131 of the mounting base material 13, and the bonding method of each member are the same as those in the first embodiment. , 2.

  The electrode materials 91 and 92 are made of Cu, for example, similarly to the mounting base material 13. The electrode material 91 has an uneven portion 911 similar to that formed on the mounting base material 13 described in the first embodiment. Is formed. The electrode materials 91 and 92 are bonded to the semiconductor chip 11 via the bonding material 12. For example, when a vertical transistor such as an IGBT is formed on the semiconductor chip 11, for example, a source electrode of the transistor is bonded to the electrode material 91, a gate electrode is bonded to the electrode material 92, and a drain electrode is mounted. Bonded to the substrate 13.

  In the joining of the semiconductor chip 11 and the mounting base material 13, when the linear expansion coefficients are different from each other, in the configuration adopted in the first embodiment, warping stress is likely to be generated in the entire semiconductor chip 11 due to the bimetal effect. For this reason, the semiconductor chip 11 is easily deformed, and the semiconductor chip 11 is easily damaged.

  On the other hand, in the fourth embodiment, as shown in FIG. 9, the electrode materials 91 and 92 are bonded to the upper surface of the semiconductor chip 11 so that the lower surface of the semiconductor chip 11 is in the same bonding state as the upper surface. As a result, the warping stress as described above is offset, and the deformation of the semiconductor chip 11 can be suppressed.

  In addition to the mounting substrate 13, electrode materials 91 and 92 are bonded to the semiconductor chip 11. For this reason, compared with the first embodiment, the heat transfer path and the heat capacity are increased, and the diffusion and transfer of heat is agile with respect to the transient heat generation of the semiconductor chip 11, and the semiconductor chip 11 caused by the transient heat generation. It becomes possible to prevent thermal destruction.

  In the fourth embodiment, each member can be joined by interposing the concavo-convex member 61 employed in the third embodiment, instead of providing the semiconductor chip 11 and the mounting substrate 13 with the concavo-convex portion. .

  The cooling performance of the semiconductor module depends on the magnitude of the thermal resistance of the heat transfer path, and is improved by thinning the bonding material 12 having a lower thermal conductivity than the mounting substrate 13. In the first embodiment, the uneven portion 131 is provided so as to straddle the electrode portion of the semiconductor chip 11 and the end portion of the joint surface of the mounting substrate 13. Thereby, the bonding material 12 under the semiconductor chip 11 flows out to the concavo-convex portion 131 on the outer periphery of the semiconductor chip 11 due to a capillary phenomenon, and the thickness of the bonding material 12 under the semiconductor chip 11 decreases. In addition, the average thickness of the bonding material 12 is reduced by the proximity of the convex portion and the semiconductor chip 11, and the cooling performance can be improved by reducing the thermal resistance.

  The long-term reliability of a semiconductor module is determined by the difference in linear expansion coefficient between different types of joints, the amount of stress concentration when thermal stress is generated, and the yield strength of each member. In the fourth embodiment, since the area and distance (thickness of the bonding material 12) of the parallel surface where the semiconductor chip 11 and the mounting substrate 13 are close to each other are determined, long-term reliability is improved by reducing the area of the parallel surface and increasing the distance. Can be improved. Since the convex portion of the concavo-convex portion 131 is inclined with respect to the semiconductor chip 11, the area of the parallel surface between the semiconductor chip 11 and the proximate portion of the convex vertex is minimized, and long-term reliability can be ensured.

  When the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in a dot shape or a line shape, the area of the parallel surface of the proximity portion is minimized. Further, since the semiconductor chip 11 and the concavo-convex portion 131 are close to each other in at least one point or line shape, the minimum thickness of the bonding material 12 in the concave portion of the concavo-convex portion 131 is ensured, and thus long-term reliability is ensured. Is possible.

  Since the bonding material 12 is not used at the bonding portion between the semiconductor chip 11 and the concavo-convex portion 131 and a direct bonding in which each material diffuses is used, a portion where no bonding material having a high thermal resistance is present is generated. It is possible to reduce the average thickness of the material and improve the cooling performance.

  By arranging and forming the uneven portion 131 on the whole or a part of the outer periphery of the bonding surface between the semiconductor chip 11 and the mounting substrate 13, it becomes possible to discharge the excess bonding material 12 outside the semiconductor chip 11. It is possible to keep the thickness of the material 12 properly and to suppress a decrease in cooling performance.

  By making the electrode materials 91 and 92 provided on the upper surface of the semiconductor chip 11 in the same bonding form as the mounting base material 13, it is possible to cancel the warping stress due to the bimetal effect and to suppress the breakage due to deformation of the semiconductor chip 11. It becomes. Also, the heat transfer path and the heat capacity are increased by bonding the upper and lower surfaces to the semiconductor chip 11, and it becomes possible to quickly diffuse and transfer the heat with respect to the transient heat generation of the semiconductor chip 11. As a result, it is possible to prevent thermal destruction of the semiconductor chip 11 due to transient heat generation.

  In the semiconductor chip 11 in which a plurality of electrode materials are bonded to the upper surface of the semiconductor chip 11, all electrode portions on the upper surface of the semiconductor chip 11 have the same structure as that of the lower surface, thereby further canceling the warping stress due to the bimetal effect. Increases, and the generation of warping stress can be minimized. Thereby, in the semiconductor chip 11 having two or more electrode portions on the upper surface, it is possible to suppress the breakage due to the deformation of the semiconductor chip 11.

DESCRIPTION OF SYMBOLS 11 ... Semiconductor chip 12 ... Bonding material 13 ... Mounting base material 61 ... Uneven member 91, 92 ... Electrode material 111, 112, 131, 131-1, 131-2, 911 ... Uneven portion 611-616, 1311-1314 ... Convex Part

Claims (8)

In a semiconductor module in which a semiconductor chip is mounted on a mounting substrate via a bonding member,
Concavities and convexities are formed on one or both of a surface of the mounting base that is to be joined to the semiconductor chip and a surface of the semiconductor chip that is to be joined to the mounting base, and the concavities and convexities are formed on the semiconductor chip and the mounting base. When the material is bonded, it is arranged so as to straddle the end of the bonding surface between the electrode portion of the semiconductor chip and the mounting substrate, and the distance between the vertices of the unevenness is the height of the protruding portion in the unevenness. A semiconductor module , wherein the mounting substrate and the semiconductor chip are closest to each other at the convex vertex of the irregularities. An electrode material is electrically bonded to a surface of the semiconductor chip opposite to a surface to which the mounting base material is bonded, a surface of the electrode material on the side to be bonded to the semiconductor chip, and the electrode material of the semiconductor chip. Concavities and convexities are formed on one or both of the surfaces to be joined, and the concavities and convexities are edges of the joining surface between the electrode portion of the semiconductor chip and the electrode material when the semiconductor chip and the electrode material are joined. 2. The semiconductor module according to claim 1, wherein the electrode material and the semiconductor chip are disposed closest to each other at a convex vertex of the unevenness. In a semiconductor module in which a semiconductor chip is mounted on a mounting substrate via a bonding member,
There is a concavo-convex member between the mounting substrate and the semiconductor chip, and the concavo-convex member is formed on the semiconductor chip when the semiconductor chip and the mounting substrate are joined with the concavo-convex member interposed therebetween. It is arranged so as to straddle the end of the joint surface between the electrode part and the mounting substrate, and the distance between the apexes of the uneven member is equal to or less than the height of the protruded part of the uneven member, and the uneven member and the semiconductor A chip is a semiconductor module that is closest to the apex of the convex portion of the concave-convex member. In the semiconductor chip, an electrode material is electrically bonded to a surface opposite to a surface to which the mounting substrate is bonded, and has a concavo-convex member between the electrode material and the semiconductor chip. When the semiconductor chip and the electrode material are joined with the uneven member interposed, the semiconductor chip and the electrode member are disposed so as to straddle the end of the joint surface between the electrode part and the electrode material, The semiconductor module according to claim 3, wherein the semiconductor chip is closest to a vertex of the convex portion of the concave-convex member. The said unevenness | corrugation or the said uneven | corrugated member is a shape which has an inclination with respect to the joint surface of the said semiconductor chip and the said mounting base material or an electrode material, The any one of Claims 1-4 characterized by the above-mentioned. Semiconductor module. 6. The semiconductor module according to claim 1, wherein at least one point or a line is close to the ridge of the concavo-convex or the concavo-convex member. The semiconductor module according to any one of claims 1 to 6, wherein the semiconductor chip and the mounting substrate or the concavo-convex member or the electrode material are bonded by the bonding material or direct bonding. The unevenness or the unevenness member is disposed and formed on all or part of the outer periphery of the bonding surface between the semiconductor chip and the mounting base material or the electrode material. 2. The semiconductor module according to item 1.

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