Method for manufacturing a semiconductor device, semiconductor device and power conversion device

Abstract

A method of manufacturing a semiconductor device, the method comprising: - feeding, in a housing (30), an insulating substrate (12) with a metal structure (12c), a semiconductor chip (16), a sintered material (18A) applied to the semiconductor chip (16) and a terminal (20); - supplying a plurality of granular sealing resins (40) supported by a grid (32) formed in the housing (30); - heating an interior of the housing (30) until its temperature reaches a first temperature higher than room temperature, and thereby releasing an evaporated solvent of the sintering material (18A) from the housing (30) to the outside via a gap of the grid (32) and a gap of the sealing resins (40); and - heating the interior of the housing (30) until its temperature reaches a second temperature higher than the first temperature, thereby causing the molten sealing resins (40) to pass through the gap of the grid (32) and form a resin layer (40') covering the semiconductor chip (16).

Description

Background area

[0001] The present invention relates to a method of manufacturing a semiconductor device, a semiconductor device and a power conversion device. General state of the art

[0002] JP 2015-220238 A discloses a semiconductor power module comprising a heat-resistant housing, an insulated circuit board on which a power semiconductor device is implemented, a heat sink in contact with the insulated circuit board to dissipate heat generated in the insulated circuit board, a heat-resistant silicone gel filled inside the heat-resistant housing, and an in-plane stress relief component disposed near a sidewall in the heat-resistant housing. The in-plane stress relief component is embedded in the heat-resistant silicone gel to prevent the heat-resistant silicone gel from peeling off from the sidewall when the heat-resistant silicone gel hardens.

[0003] For example, in a case where a semiconductor device of a power module or the like is to be manufactured, a semi-finished product often needs to be moved at each step of the manufacturing process to supply the semi-finished product into a semiconductor manufacturing facility and remove the semi-finished product from the semiconductor manufacturing facility. For example, the semi-finished product may be heated by a heater to bond a semiconductor chip to a lead or metal pattern using solder, and then the semi-finished product may be removed from the heater and cooled, a material for a sealing resin may be provided, and the semi-finished product may be heated again by the heater to melt the sealing resin.As a result, for example, when it is necessary to add a component such as a sealing resin to the semi-finished product being manufactured, the semi-finished product whose temperature has been raised must be cooled and then heated again to raise its temperature, which makes it difficult to shorten the time required to manufacture the semiconductor device.

[0004] EP 1 355 351 A1 discloses a semiconductor device comprising a semiconductor element formed within a housing, a bonding wire, a sealing resin member covering the semiconductor element and the bonding wire, and a plate member. The plate member is mounted in the housing and disposed out of contact with the bonding wire, and further embedded in the sealing resin member. Since the plate member prevents the sealing resin member from vibrating, the bonding wire is connected with improved reliability. Instead of the plate member, it is possible to use a columnar member mounted on an insulating substrate. The semiconductor device is intended to be suitable for use on a moving body, such as a vehicle, that travels with vibrations.

[0005] WO 2018 / 185 974 A1 describes a semiconductor device in which residual tiny air bubbles generated in a resin injection step are prevented and in which the flow of a sealant into a region to be sealed with resin is facilitated. Furthermore, a method for its production and a power conversion device comprising such a semiconductor device are presented. This known semiconductor device comprises an insulating substrate, a semiconductor element, a conductor substrate, and a housing part. The semiconductor element is connected over the insulating substrate, and the conductor substrate is connected over the semiconductor element. The housing part encloses a region that overlaps with the insulating substrate, the semiconductor element, and the conductor substrate in plan view, leaving said region open. A plurality of metal patterns are arranged on a main surface of an insulating layer.A groove is formed between a pair of adjacent metal patterns of the plurality of metal patterns. A through hole is formed in the conductor substrate at a position overlapping the groove in plan view.

[0006] DE 11 2017 007 415 T5 discloses a semiconductor device in which residual tiny air bubbles generated in a resin injection step are prevented and in which the flow of a sealant into a region to be sealed with resin is facilitated. Furthermore, a method for its production and a power conversion device including such a semiconductor device are disclosed. This known semiconductor device comprises an insulating substrate, a semiconductor element, a conductor substrate, and a housing part. The semiconductor element is connected over the insulating substrate, and the conductor substrate is connected over the semiconductor element. The housing part encloses a region that overlaps with the insulating substrate, the semiconductor element, and the conductor substrate in plan view, leaving said region open. A plurality of metal patterns are arranged on a main surface of an insulating layer.A groove is formed between a pair of adjacent metal patterns of the plurality of metal patterns. A through hole is formed in the conductor substrate at a position overlapping the groove in plan view.

[0007] JP 2014-154 679 A discloses a semiconductor module that achieves cost advantages through a simple manufacturing process and achieves high soldering accuracy through columnar metal bodies with a uniform height.A semiconductor module includes a semiconductor element having an electrode on the top surface, a lower circuit board having a bottom surface fixed to the top surface, an upper circuit board having a plurality of columnar metal bodies disposed opposite to the electrode of the semiconductor element and a wiring pattern integrally formed with the columnar metal bodies, and a side terminal member disposed laterally of the upper circuit board, wherein the plurality of columnar metal bodies are formed from a metal plate by etching, the electrode and the columnar metal bodies are connected to each other by soldering, the upper circuit board extends to the side terminal member; and the wiring pattern is electrically connected to the side terminal member. Summary

[0008] The present invention addresses the problem identified above, and an object of the present invention is to provide a method of manufacturing a semiconductor device, a semiconductor device, and a power conversion device that make it possible to shorten the time required to manufacture a semiconductor device.

[0009] The object underlying the invention is achieved in a method for producing a semiconductor device according to the invention with the features of claim 1, in a semiconductor device according to the invention with the features of claim 12, and in a power conversion device according to the invention with the features of claim 15. Advantageous further developments are the subject of the respective dependent claims.

[0010] The method for manufacturing a semiconductor device according to the invention comprises supplying, into a package, an insulating substrate having a metal structure, a semiconductor chip, a sintering material deposited on the semiconductor chip, and a lead; supplying a plurality of granular sealing resins supported by a mesh formed in the package; heating an interior of the package until its temperature reaches a first temperature higher than room temperature, thereby releasing an evaporated solvent of the sintering material from the package to the outside via a gap of the mesh and a gap of the sealing resins; and heating the interior of the package until its temperature reaches a second temperature higher than the first temperature, thereby causing the molten sealing resins to pass through the gap of the mesh and form a resin layer covering the semiconductor chip.

[0011] Other and further objects, features and advantages of the invention will become more fully apparent from the following description. Short description of the drawings Fig. 1 is a perspective cross-sectional view of a semi-finished semiconductor device according to a first embodiment; Fig. 2 is a cross-sectional view of the semiconductor device where granular sealing resins are shown; Fig. 3 is a cross-sectional view of the resin-sealed semiconductor device; Fig. 4 is a perspective cross-sectional view of a semi-finished semiconductor device according to a second embodiment; Fig. 5 is a cross-sectional view of the semiconductor device with two kinds of sealing resins; Fig. 6 is a cross-sectional view of the semiconductor device whose two kinds of sealing resins are melted; Fig. 7 is a plan view of the grid according to a third embodiment; Fig. 8 is a plan view of the grating according to a fourth embodiment; Fig. 9 is a perspective cross-sectional view of a semiconductor device showing the grid of Fig. 8 contains; and Fig. Figure 10 is a block diagram illustrating a power conversion system. Detailed description

[0012] A method for manufacturing a semiconductor device, the semiconductor device, and a power conversion device according to embodiments of the present invention will be described below with reference to the drawings. The same or corresponding components are denoted by the same reference numerals, and detailed explanations thereof will not be repeated to avoid redundancy. First embodiment

[0013] A method of manufacturing a semiconductor device according to the first embodiment will be described with reference to Fig. 1 to 3. Fig. 1 is a perspective cross-sectional view of a semiconductor device being manufactured in its manufacturing process. First, a semiconductor chip 16 is attached to a metal pattern 12c of an insulating substrate 12. For example, a sintering material such as Ag or Cu or a bonding material 14 made of solder is provided on the metal pattern 12c, and the semiconductor chip 16 is attached to the metal pattern 12c using the bonding material 14. The insulating substrate 12 may include a metal base plate 12a, an insulating layer 12b formed on the metal base plate 12a, and a metal pattern 12c formed on the insulating layer 12b.

[0014] Subsequently, the insulating substrate 12 is attached to a housing 30. The housing 30 may be a four-sided enclosure. The insulating substrate 12 is attached to the inner wall or the bottom end of the housing 30. The specific methods for attaching the insulating substrate 12 to the housing 30 may include using an adhesive, mechanical fitting, etc. A grid 32 may be previously attached to the housing 30. The grid 32 may be provided over the semiconductor chip 16 in the housing 30 such that the grid 30 faces the insulating substrate 12. As an example, the grid 32 and the semiconductor chip 16 may be parallel to each other. The grid 32 may be provided as part of the housing 30. In this case, the housing 30 and the grid 32 are integral with each other and made of the same material.If the housing 30 is made of resin, then, for example, the grille 32 can also be made of resin. The grille 32 can be provided as a separate component, separated from the housing 30. In this case, all or part of the ends of the grille 32 can be attached to the inner wall of the housing 30, for example, using an adhesive. It is also possible to form a groove extending in a z-direction on the inner wall of the housing 30 to snug-fit the grille 30 with the groove. Fig. 1 illustrates such a groove 30a virtually indicated by dashed lines. The groove 30a may be formed on at least one of the inner walls of the housing 30.

[0015] A sintering material 18A such as Ag or Cu is applied to the wiring locations on the semiconductor chip 16 before or after the insulating substrate 12 is attached to the package 30. At the same time, sintering materials 18B, 18C, 18D are applied to the metal structure 12c. These sintering materials are provided as a sintering bonding paste made of Ag or Cu. A sintering material made of any material other than Ag and Cu may also be used. According to one example, at least one of the sintering materials 18A, 18B, 18C, 18D may be provided by providing the sintering material in a cylindrical section 30A provided as part of the package 30 in contact with the grid 32. A circuit wiring can be formed by bringing terminals 20, 22, 24 made of a metal such as Cu into contact with the sintered materials 18A, 18B, 18C, 18D.

[0016] Through the process described above, the insulating substrate 12 with the metal structure 12c, the semiconductor chip 16, the sintered material 18A applied to the semiconductor chip 16, and the terminals 20, 22, 24 are provided inside the housing 30. The individual steps of the process described above can generally be associated with the purpose of forming the circuit structure.

[0017] Subsequently, several granular sealing resins are fed into the housing 30. Fig. 2 is a cross-sectional view of the semiconductor device, where the granular sealing resins 40 are shown. The shape of the sealing resins 40 is not limited to any specific one. However, the sealing resins 40 are sized larger than the opening of the grid 32 so as not to fall off the grid 32. As a result, when the sealing resins 40 are fed into the housing 30 in the negative direction in the z-direction, the sealing resins 40 are supported by the grid 32 provided inside the housing 30.

[0018] Subsequently, a semi-finished product of the semiconductor device described above is fed into a high-temperature processing device such as a furnace or reflow furnace and subjected to a high-temperature thermal treatment, thereby performing the sintering process for the sintering materials 18A, 18B, 18C, 18D and the curing process for the sealing resins 40. For example, the temperature of the semiconductor device is continuously or stepwise raised, and the solvents used in the sintering materials 18A, 18B, 18C, 18D are evaporated. At this point, the evaporated solvents of the sintering materials are released to the outside of the housing 30 via the gaps of the grid 30 and the gaps of the sealing resins 40. In the context of the Fig. 2, the evaporated solvents move upward in the positive direction in the z-direction to be released from the housing 30 to the outside. The evaporation of the solvents and the release of the evaporated solvents are realized by heating the interior of the housing 30 until its temperature reaches a first temperature above room temperature. As a result of the sintering process, the lead 20 is attached to the metal structure 12c; the lead 22 is attached to the semiconductor chip 16 and the metal structure 12c; and the lead 24 is attached to the metal structure 12c. As a result, the solvents disappear. No significant melting of the sealing resins 40 occurs in a state where the interior of the housing 30 is at the first temperature.According to one example, the temperature at which the solvents used in the sintering materials 18A, 18B, 18C, 18D evaporate is 100°C and the first temperature may be in the range of 100°C to 150°C.

[0019] Subsequently, the interior of the housing 30 is heated until its temperature reaches a second temperature higher than the first temperature to melt the sealing resins 40. The second temperature may be defined, for example, within the range of 170°C to 250°C. Fig. 3 is a cross-sectional view of the resin-sealed semiconductor device. The molten sealing resins 40 pass through the gaps of the grid 32 and form a resin layer 40' covering the semiconductor chip 16. In other words, the molten sealing resins 40 flow downward from the grid 32 of the package 30 and begin to harden after spreading over the entire insulating substrate 12, thus completing the formation of the sealing resin by the resin layer 40' and its hardening.

[0020] As described above, the sintering process and the formation and curing of the sealing resin are completed through the series of steps of the temperature-elevating process. Since the gas generated by evaporation of the solvents used in the sintering materials 18A, 18B, 18C, 18D is released to the outside through the gaps of the grid 32 and the gaps of the multiple granular sealing resins 40, the generation of voids in the resin layer 40' can be suppressed. To achieve this effect, the material for the sealing resins 40 should be selected so that the sealing resins 40 do not exhibit significant deformation at the temperature at which the solvents used in the sintering materials 18A, 18B, 18C, 18D evaporate.According to one example, after the solvents have evaporated, the sealing resins 40 melt and begin to flow, thereby beginning the resin sealing process, and the manufacturing is completed by finally sealing the entire interior of the housing 30 with the resin layer 40'.

[0021] For example, the sintering temperature of the sintered materials 18A, 18B, 18C, 18D can be up to 200°C or higher, whereupon the glass transition temperature Tg of the sealing resins 40 can be increased. Also, a defect in the resin layer 40' can be reduced by creating a vacuum atmosphere in a chamber accommodating the semiconductor device immediately before the sealing resins 40 begin to flow. In other words, setting the pressure of the atmosphere around the housing 30 lower than atmospheric pressure when heating the interior of the housing 30 until its temperature reaches the second temperature contributes to reducing voids in the resin layer 40'. The sequence of steps of the heating process described above can be performed at a pressure lower than atmospheric pressure or in a vacuum state.

[0022] The temperature raising sequence for raising the temperature above the first temperature to the second temperature can be defined taking into account the degree of sintering progress and the degree of melting of the sealing resin. For example, it contributes to simplifying the process by heating the interior of the case 30 to the second temperature without cooling the interior of the case 30 after the interior of the case 30 has been heated until its temperature reaches the first temperature. The method for manufacturing a semiconductor device according to the first embodiment makes it possible to produce a highly reliable semiconductor device through a simplified process.

[0023] Various modifications can be made to the semiconductor device according to the first embodiment, as long as the semiconductor device has its intended features. For example, it is also possible to provide only one of the sintered material 18A that connects the semiconductor chip 16 and the terminal 22, and the sintered materials 18B, 18C, 18D that connect the metal structure 12c and the terminals 22, 22, 24. That is, the locations where the sintered materials are to be provided are not limited to specific ones. The sintered materials can be used to connect any suitable components within the package. The grid 32 can be attached to the package 30 by an adhesive, or it can be snugly fitted to the package 30.

[0024] Since the methods for manufacturing a semiconductor device and the semiconductor devices according to the following embodiments have much in common with those according to the first embodiment, a description of the following embodiments will focus on the features different from those in the first embodiment. Second embodiment

[0025] Fig. 4 to 6 are diagrams illustrating the method of manufacturing a semiconductor device according to a second embodiment. The semiconductor device according to the second embodiment includes a top grid 50. The top grid 50 is provided on the grid 32 inside the case 30. The top grid 50 may be fixed to the inner wall of the case 30 by means of an adhesive or a press fit therewith. According to one example, an opening provided by the top grid 50 is larger than the opening provided by the grid 32. While the grid 32 can support a relatively small sealing resin, the top grid 50 has the larger opening and cannot support a small sealing resin, but can support a relatively large sealing resin.

[0026] Fig. 5 is a cross-sectional view of the semiconductor device diagram illustrating a state where two types of sealing resins are provided inside the package. According to the method for manufacturing a semiconductor device according to the second embodiment, when the sealing resins 40A are supplied in the negative direction in the z-direction into the package 30, the sealing resins 40A pass through the upper grid 50 to be brought into contact with the grid 32 and supported by the grid 32. After that, a plurality of additional sealing resins 40B are supplied in the negative direction in the z-direction into the package 30. The additional sealing resins 40B are larger than the sealing resins 40A and are supported by the upper grid 50. According to one example, the additional sealing resins 40B may be a granular object having a higher melting point than that of the sealing resins 40A.In this way, the sealing resins 40A supported by the grid 32 and the additional sealing resins 40B supported by the upper grid 50 are provided. According to one example, the melting point of the sealing resins 40A may be 150°C, while the melting point of the additional sealing resins 40B may be 175°C. The additional sealing resins 40B may also be made of a resin that is less likely to absorb moisture than the sealing resins 40A. In other words, the additional sealing resins 40B have a lower water absorption rate than that of the sealing resins 40A. The physical properties of the resin, such as melting point and water absorption rate, can be tuned to any suitable values, for example, by using epoxy resin to form the additional sealing resins 40B and the sealing resins 40A and adjusting the components of the epoxy resin.Epoxy resin can also be used to form resins other than those of the second embodiment.

[0027] A heat treatment is then carried out. Fig. 5 is a cross-sectional view of the semiconductor device which has not yet undergone the heat treatment. Fig. 6 is a cross-sectional view of the semiconductor device that has undergone the heat treatment. As described above, first, the interior of the package is heated until its temperature reaches the first temperature to perform the sintering process. The first temperature is, for example, lower than 150°C. At this point, no significant melting of the sealing resin 40A and the additional sealing resin 40B occurs. Thereafter, the sealing resin 40A is melted by heating the interior of the package 30 to the second temperature without cooling the interior of the package 30. The second temperature is, for example, 150°C or higher and lower than 175°C. The resin layer 40A' is thus, as shown in Fig. 6. According to another example, the second temperature may also be 170°C or higher and lower than 180°C, and the melting point of the sealing resin 40A may be defined within this temperature range. The second temperature may be defined as any suitable temperature at which the sealing resin 40A is melted.

[0028] The additional sealing resins 40B are melted by heating the interior of the housing 30 to a third temperature higher than the second temperature after the interior of the housing 30 is heated to the second temperature. The third temperature may be 175°C or higher and 250°C or lower. According to another example, the third temperature may be defined as a temperature from 180°C to 250°C, and the melting point of the additional sealing resins 40B may be defined within this temperature range. The molten additional sealing resins 40B pass through the gaps of the upper grid 50 and the gaps of the grid 32, forming an additional resin layer 40B' on the resin layer 40A'. In this way, it is possible to realize resin sealing of the interior of the housing by utilizing the resin layer 40A' and the additional resin layer 40B' with different physical properties.Since the water absorption rate of the additional sealing resins 40B is lower than that of the sealing resins 40A, the moisture resistance of the device can be improved by disposing the additional resin layer 40B' having the lower water absorption rate on the surface of the device.

[0029] Setting the atmospheric pressure around the housing 30 lower than atmospheric pressure when the temperature of the interior of the housing 30 is increased until the temperature reaches the third temperature contributes to reducing voids in at least one of the resin layer 40A' and the additional resin layer 40B'. The process is also accelerated by heating the interior of the housing 30 to the third temperature without cooling the interior of the housing 30 after the interior of the housing 30 has been heated until the temperature reaches the second temperature.

[0030] The reliability of a semiconductor device constituting a power module can be improved by injecting and curing two types of sealing resins made of different materials depending on the types of semiconductor devices. However, in order for the resin layer to have a two-layer structure, forming the two-layer resin layer generally requires a longer time than forming a single-layer resin layer. Meanwhile, according to the method for manufacturing a semiconductor device according to the second embodiment described above, a grid having a two-stage structure is provided in the case 30, and the sealing resin is supplied into each layer of the grid, so that the two-layer resin layer can be easily formed through a series of steps of the temperature elevating process.A resin layer with three or more layers can also be formed by increasing the number of grids.

[0031] Since the gaps of the upper grid 50 are formed larger than the gaps of the grid 32, a small sealing resin can be supported by the grid 32, and a larger sealing resin can be supported by the upper grid 50. The small sealing resin should be sized to ensure that the sealing resin passes through the upper grid 50 and is supported by the grid 32, while the large sealing resin should be sized to allow the sealing resin to be supported by the upper grid 50. In the second embodiment, the additional sealing resins 40B are larger than the sealing resins 40A. However, the upper grid 50 may not be provided, and the additional sealing resins 40B may be provided on the sealing resins 40A after the sealing resins 40A are provided.In this case too, the materials for the sealing resins can be selected so that in the process of temperature raising, the sealing resins 40A melt first and then the additional sealing resins 40B melt, so that the sealing resin having the two-layer structure can be provided. Third embodiment

[0032] According to a method of manufacturing a semiconductor device and the semiconductor device according to a third embodiment, the housing and the grid are provided as two separate components. Fig. 7 is a plan view illustrating an example of the configuration of the grid 32 according to the third embodiment. A plurality of unconnected portions 32a, 32b, 32c, 32d may be provided in the grid 32 to pass a terminal therethrough. The size and location of the unconnected portions can be determined as appropriate according to the specifications of the product. Such a grid 32 may be integrated into the housing 30 before providing the plurality of resins into the housing. For example, the grid 32 may be integrated into the housing 30 after the insulating substrate 12 is attached to the housing 30 to supply the resin. Providing the housing and the grid as two separate components makes it possible to provide an optimal grid that corresponds to the physical properties of the resins, the internal shape of the power module, or a terminal arrangement. Fourth embodiment

[0033] Fig. 8 is a plan view illustrating an example of the configuration of the grid 32 used in a semiconductor device according to a fourth embodiment. This grid 32 includes an insulator portion 32A and a metal portion 32B. The metal portion 32B is used as a wiring structure for implementing electrical wiring for the power module.

[0034] Fig. 9 is a perspective cross-sectional view of an example of the configuration of a semiconductor device using the Fig. 8. The grid 32 is attached to the inner wall of the housing 30. The metallic part 32B is in contact with the terminals 22A, 22B directly or via a conductive material. The metallic part 32B electrically connects the terminal 22A and the terminal 22B. Since the metallic part 32B functions as a wiring structure, it is possible to conform to various wiring layouts according to the types without changing the shape of the housing 30.

[0035] More detailed explanations are provided below. When a variety of power modules with different voltages or different current capacities are to be implemented while maintaining the same standardized external shape of the housing, different wiring configurations are required depending on the specifications. A metallic wire is used as the wiring component. If a large current flow must be considered, a metal frame made of copper can be used instead of a metallic wire. If the metal frame is to be integrated into the housing, it will be necessary to provide housings with different shapes depending on the type, and molds for manufacturing housings according to the number of types will be required.For example, a change in the position of the semiconductor chip relative to the insulating substrate will require a change in the wiring layout and a new package.

[0036] In view of this, according to the fourth embodiment, a grid 32 with a metallic part 32B functioning as a wiring component is integrated into the interior of the housing 30 after the housing 30 and the insulating substrate 12 are combined. Since the metallic part 32B is used as a wiring component, the time and effort involved in changing the wiring can be reduced, and the overall product cost can be reduced. In particular, for example, if the terminals, which are a metallic frame, can be simplified, the degree of freedom in design increases. The metallic frame can be formed integrally with the grid or can be a component combined with the grid.

[0037] The features of the methods for manufacturing a semiconductor device and the semiconductor devices according to the respective embodiments described above can be combined as appropriate. For example, in a configuration where grids are provided in multiple stages, a portion of the grids may be provided as a metallic part that can be used as a wiring component. Fifth embodiment

[0038] This embodiment is a type of realization in which the semiconductor device according to the first to fourth embodiments described above is implemented on a power conversion device. While the power conversion device is not limited to a specific power conversion device, an example will be described below as a fifth embodiment in which the semiconductor device according to the first to fourth embodiments described above is implemented on a three-phase inverter.

[0039] Fig. 10 is a block diagram illustrating the configuration of a power conversion system in which the power conversion device according to this embodiment is implemented.

[0040] The Fig. The power conversion system illustrated in Figure 10 includes a power source 100, a power conversion device 200, and a load 300. The power source 100 is a DC power source and provides DC power to the power conversion device 200. The power source 100 can be formed by various types of power supplies. For example, the power source 100 can be formed by a DC power system, a solar cell, or a secondary battery, or can be formed by a rectifier circuit connected to an AC power system or an AC / DC converter. The power source 100 can also be formed by a DC / DC converter that converts DC power output from a DC power system into a predefined electrical power.

[0041] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300. The power conversion device 200 converts DC power provided by the power source 100 into AC power and provides the AC power to the load 300. The power conversion device 200 includes, as shown in Fig. 10, a main conversion circuit 201 that converts DC power into AC power and outputs the AC power, and a control circuit 203 that outputs a control signal for controlling the main conversion circuit 201 to the main conversion circuit 201.

[0042] The load 300 is a three-phase electric motor driven by the AC power provided by the power conversion device 200. It should be noted that the load 300 is not limited to specific applications and can be an electric motor mounted in various electrical devices. For example, the load 300 can be used as an electric motor for hybrid vehicles, electric vehicles, rail vehicles, elevators, or an air conditioning system.

[0043] The following describes details of the power conversion device 200. The main conversion circuit 201 includes a switching element and a freewheeling diode (not shown). Switching the switching element causes the DC power supplied by the power source 100 to be converted into AC power, and thereby the main conversion circuit 201 supplies the AC power to the load 300. While various circuit configurations can be considered as the specific circuit configuration of the main conversion circuit 201, the main conversion circuit 201 according to this embodiment is a two-level, three-phase full-bridge circuit formed by six switching elements and six freewheeling diodes connected in antiparallel to the respective switching elements.The semiconductor device corresponding to one of those according to the first to fourth embodiments described above is implemented on at least one of the respective switching elements and the respective freewheeling diodes of the main conversion circuit 201. The six switching elements are connected in series two by two to form the upper and lower arms, and each of the upper and lower arms forms a phase (U-phase, V-phase, and W-phase) of the full-bridge circuit. Furthermore, the output terminals of the respective upper and lower arms, that is, the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0044] The main conversion circuit 201 also includes a drive circuit (not shown) that drives the switching elements; however, the drive circuit may be embedded in the semiconductor device 202 or may be configured to include a drive circuit independent of the semiconductor device 202. The drive circuit generates a drive signal for driving the switching elements of the main conversion circuit 201 and provides the drive signal to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, the drive circuit outputs a drive signal that places the switching element in an enabled state and a drive signal that places the switching element in a disabled state to the control electrodes of the switching elements according to a control signal from the control circuit 203 (described later).If the switching element is to be kept in the enabled state, the drive signal is a voltage signal (enable signal) equal to or higher than the threshold voltage of the switching element. If the switching element is to be kept in the disabled state, the drive signal is a voltage signal (disable signal) equal to or lower than the threshold voltage of the switching element.

[0045] The control circuit 203 controls the switching element of the main conversion circuit 201 to supply a desired electrical power to the load 300. Specifically, the control circuit 203 calculates the time (release time) at which the switching elements of the main conversion circuit 201 should be placed in the released state based on the electrical power to be supplied to the load 300. For example, the main conversion circuit 201 can be controlled according to the voltage to be output using a PWM controller that performs modulation associated with the release time of the switching elements.In addition, at each time, the control command (control signal) is output to the drive circuit included in the main conversion circuit 201, so that an enable signal is output to the switching element to be enabled and a disable signal is output to the switching element to be disabled. The drive circuit outputs the enable signal or the disable signal to the control electrodes of the switching elements as the drive signal according to the control signal.

[0046] According to the power conversion device according to this embodiment, since the semiconductor device according to the first to fourth embodiments can be implemented as the switching element and the freewheeling diode of the main conversion circuit 201, a highly reliable device can be achieved through a simplified process.

[0047] While this embodiment has been described based on the example in which the above-described semiconductor device is implemented on a three-phase two-level inverter, the above-described semiconductor device is not limited to this example and may be implemented on various power conversion devices. According to this embodiment, the power conversion device is implemented as a two-level power conversion device; however, it may be implemented as a three-level or more power conversion device. If electric power is to be supplied to a single-phase load, the above-described semiconductor device may also be implemented as a single-phase inverter. If electric power is to be supplied to a DC load, etc., then the above-described semiconductor device may also be implemented as a DC / DC converter or an AC / DC converter.

[0048] The power conversion device implementing the above-described semiconductor device is not limited to a case where the above-described load is an electric motor, but can also be used, for example, as a power supply device for an electrical discharge machine, a laser machine, an induction heating cooking device, or a non-contact power supply system. Furthermore, the power conversion device can also be used as a power conditioner of a solar power generation system, a power storage system, etc.

[0049] Since the grid is provided in the package and the sealing resin is provided on the grid, it is possible to continuously carry out the bonding process for connecting components together and the melting process for melting the sealing resin, which is advantageous in terms of shortening the time required for manufacturing a semiconductor device.

Claims

[1] A method of manufacturing a semiconductor device, the method comprising: - feeding, in a housing (30), an insulating substrate (12) with a metal structure (12c), a semiconductor chip (16), a sintered material (18A) applied to the semiconductor chip (16) and a terminal (20); - supplying a plurality of granular sealing resins (40) supported by a grid (32) formed in the housing (30); - heating an interior of the housing (30) until its temperature reaches a first temperature higher than room temperature, and thereby releasing an evaporated solvent of the sintering material (18A) from the housing (30) to the outside via a gap of the grid (32) and a gap of the sealing resins (40); and - heating the interior of the housing (30) until its temperature reaches a second temperature higher than the first temperature, thereby causing the molten sealing resins (40) to pass through the gap of the grid (32) and form a resin layer (40') covering the semiconductor chip (16). [2] The method according to claim 1, wherein when the interior of the housing (30) is heated until its temperature reaches the second temperature, a pressure of one atmosphere around the housing (30) is established lower than the atmospheric pressure. [3] The method according to claim 1 or 2, wherein the sintering material (18A) bonds the semiconductor chip (16) and the terminal (22) to each other. [4] A method according to any one of claims 1 to 3, wherein, after the interior of the housing (30) has been heated until its temperature reaches the first temperature, cooling of the interior of the housing (30) does not take place and the interior of the housing (30) is then heated so that its temperature reaches the second temperature. [5] Method according to one of claims 1 to 4, further comprising: - after the sealing resins (40A) carried by the grid (32) have been supplied, supplying a plurality of granular additional sealing resins (40B) carried by an upper grid (50) formed on the grid (32) in the housing (30) and having a higher melting point than that of the sealing resin (40A); and - after the interior of the housing (30) has been heated until its temperature reaches the second temperature, heating the interior of the housing (30) until its temperature reaches a third temperature which is higher than the second temperature, thereby causing the molten additional sealing resins (40B) to pass through a gap of the upper grid (50) and form an additional resin layer (40B') on the resin layer (40A'). [6] The method according to claim 5, wherein when the interior of the housing (30) is heated until its temperature reaches the third temperature, a pressure of one atmosphere around the housing (30) is established lower than an atmospheric pressure. [7] A method according to claim 5 or 6, wherein, after the interior of the housing (30) has been heated until its temperature reaches the second temperature, cooling of the interior of the housing (30) does not take place and the interior of the housing (30) is then heated until its temperature reaches the third temperature. [8] The method according to any one of claims 5 to 7, wherein the gap of the upper grid (50) is larger than the gap of the grid (32) and the additional sealing resins (40B) are larger than the sealing resins (40A). [9] A method according to any one of claims 1 to 8, wherein the grid (32) is integrated into the housing (30) before the resins are supplied. [10] The method of claim 9, wherein the grid (32) comprises a metallic part (32B). [11] The method of claim 10, wherein the metallic part (32B) is in contact with the terminal (22A, 22B) directly or via a conductive material. [12] Semiconductor device, comprising: - a housing (30); - an insulating substrate (12) having a metal structure (12c) and fixed to the housing (30); - a semiconductor chip (16) formed in the housing (30) and attached to the metal structure (12c); - a sealing resin (40') covering the semiconductor chip (16); and - a grid (32) formed over the semiconductor chip (16) in the housing (30) such that the grid (32) faces the insulating substrate (12), where: - the grid (32) has a metallic part (32B) and - a terminal (22A, 22B) is formed directly or via a conductive material in contact with the metallic part (32B). [13] A semiconductor device according to claim 12, wherein the grid (32) is fixed to the housing by an adhesive. [14] A semiconductor device according to claim 12, wherein the grid (32) is fitted into a snug fit with the housing (30). [15] Power conversion device comprising: - a main conversion circuit (201) comprising the semiconductor device according to any one of claims 12 to 14, wherein the main conversion circuit (201) is configured to convert an input electrical power and output the converted electrical power; and - a control circuit (203) configured to output a control signal controlling the main conversion circuit (201) to the main conversion circuit (201).

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