Method of manufacturing a semiconductor device

Abstract

A manufacturing method of a semiconductor device capable of suppressing manufacturing costs and reliably leading out electrode components from the upper surface of the device. A semiconductor chip having a main electrode and a control electrode is bonded to a substrate. A wiring chip having a first electrode, a second electrode, and a wiring connecting them is bonded to the substrate. A main electrode component is bonded to the main electrode via a first bonding material. A control electrode component is bonded to the second electrode via a second bonding material. The control electrode and the first electrode are connected by a connecting component. The bonded semiconductor chip, substrate, wiring chip, main electrode component, control electrode component, and connecting component are placed in a mold, and a packaging material is injected into the mold while pressing the front end surfaces of the main electrode component and the control electrode component against a buffer material provided between them and the mold, and the semiconductor chip, substrate, wiring chip, main electrode component, control electrode component, and connecting component are encapsulated by this. The packaging material is not ground.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor device. Background Art

[0002] It is difficult to increase the area of a SiC MOSFET. Therefore, in order to increase the current capacity of a module using a SiC MOSFET, multiple chips need to be connected in parallel. A semiconductor device has been proposed in which multiple semiconductor chips and wiring chips are bonded to a substrate, and the control electrodes of the respective semiconductor chips are connected in parallel through the circuit pattern of the wiring chip (for example, refer to Patent Document 1). A main electrode component is bonded to the main electrodes of multiple semiconductor chips, and after a control electrode component is bonded to the circuit pattern of the wiring chip, resin encapsulation is performed.

[0003] Patent Document 1: International Publication No. 2020 / 110170

[0004] In the prior art, the encapsulation material is ground to expose the electrode component from the encapsulation material. However, there are the following problems: dust is generated in the grinding process, and moisture intrudes from the grinding surface in the case of wet grinding. In addition, due to fluctuations in the height of the electrode component, the electrode component is excessively ground during grinding, so there are problems of waste of materials and processing time and difficulty in end detection. Also, the processing cost of the grinding itself is incurred. Summary of the Invention

[0005] The present invention has been made to solve the above-described problems, and an object thereof is to obtain a method for manufacturing a semiconductor device that can suppress the manufacturing cost and reliably lead out an electrode component from the upper surface of the device.

[0006] The method for manufacturing a semiconductor device according to the present invention is characterized by including the following steps: bonding a semiconductor chip having a main electrode and a control electrode to a substrate; bonding a wiring chip having a first electrode, a second electrode, and a wiring connecting the first electrode and the second electrode to the substrate; bonding a main electrode component to the main electrode via a first bonding material; bonding a control electrode component to the second electrode via a second bonding material; connecting the control electrode and the first electrode through a connecting component; and placing the bonded semiconductor chip, substrate, wiring chip, main electrode component, control electrode component, and connecting component in a mold, and injecting an encapsulation material into the mold in a state where the front end surfaces of the main electrode component and the control electrode component are pressed against a buffer material provided between the main electrode component, the control electrode component, and the mold, and encapsulating the semiconductor chip, substrate, wiring chip, main electrode component, control electrode component, and connecting component with the encapsulation material without grinding the encapsulation material.

[0007] Effect of the Invention

[0008] In the present invention, even if there are fluctuations in the heights of the control electrode member and the main electrode member, resulting in gaps between the main electrode member and the control electrode member and the mold, the buffer material will fill these gaps. Therefore, in the encapsulation process, the front end faces of the main electrode member and the control electrode member are not covered by the encapsulation material but are exposed. Thus, after the encapsulation process, the encapsulation material does not need to be ground. As a result, the manufacturing cost can be suppressed and the electrode member can be reliably led out from the upper surface of the device. Description of the Drawings

[0009] Figure 1 It is a cross-sectional view showing a semiconductor device according to Embodiment 1.

[0010] Figure 2 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to Embodiment 1.

[0011] Figure 3 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to Embodiment 1.

[0012] Figure 4 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to Embodiment 1.

[0013] Figure 5 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to Embodiment 1.

[0014] Figure 6 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to Embodiment 1.

[0015] Figure 7 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to Embodiment 1.

[0016] Figure 8 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to a comparative example.

[0017] Figure 9 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to a comparative example.

[0018] Figure 10 It is a cross-sectional view showing a manufacturing method of a semiconductor device according to a comparative example.

[0019] Figure 11 It is a cross-sectional view showing the front end portion of the main electrode member after encapsulation.

[0020] Figure 12 It is a cross-sectional view showing a modification of the manufacturing method of a semiconductor device according to Embodiment 1.

[0021] Figure 13 It is a cross-sectional view of the semiconductor device related to Embodiment 2.

[0022] Figure 14 It is a cross-sectional view of the manufacturing method of the semiconductor device related to Embodiment 2.

[0023] Figure 15 It is a cross-sectional view of the manufacturing method of the semiconductor device related to Embodiment 2.

[0024] Figure 16 It is a cross-sectional view of the manufacturing method of the semiconductor device related to Embodiment 2. Detailed Embodiment

[0025] With reference to the accompanying drawings, the manufacturing method of the semiconductor device related to the embodiment will be described. The same reference numerals are assigned to the same or corresponding structural elements, and repeated descriptions may be omitted sometimes.

[0026] Embodiment 1

[0027] Figure 1 It is a cross-sectional view of the semiconductor device related to Embodiment 1. A plurality of semiconductor chips 1 and one wiring chip 2 are bonded to a substrate 3. The semiconductor chip 1 has a back electrode 4 on the back side and a main electrode 5 and a control electrode 6 on the front side. The semiconductor chip 1 is, for example, a MOSFET. The control electrode 6 is, for example, a gate electrode or a Kelvin source electrode. When a temperature sensing element or a current sensing element is built in the semiconductor chip 1, it also has control electrodes corresponding to the temperature sensing element and the current sensing element respectively.

[0028] The back electrode 4 is, for example, a metal film in which a silicide layer / titanium layer / nickel layer / titanium layer / gold or silver layer is laminated from the semiconductor chip 1 side by sputtering. The main electrode 5 and the control electrode 6 are, for example, a metal film in which an aluminum layer is formed on the semiconductor chip 1 by sputtering and a nickel layer / palladium layer / gold layer is laminated on the aluminum layer by plating. Alternatively, the main electrode 5 and the control electrode 6 may also be, for example, a metal film in which an aluminum layer / titanium layer / nickel layer / titanium layer / gold or silver layer is laminated by sputtering. In addition to this, a laminated film having a similar function can also be selected.

[0029] The wiring chip 2 has a bonding layer 7 on the back side and a first electrode 8, a second electrode 9, and a wiring 10 connecting the first electrode 8 and the second electrode 9 on the front side. The wiring chip 2 is, for example, an element made of silicon, and an insulating film such as an oxide film is formed on the Si surface, and the first electrode 8, the second electrode 9, and the wiring 10 are formed on the insulating film. The first electrode 8, the second electrode 9, and the wiring 10 are, for example, wiring patterns made of aluminum. At least a bondable metal layer is provided above the second electrode 9. The same metal layer may also be provided above the first electrode 8. The bondable metal layer is, for example, the same laminated metal film as the main electrode 5 of the semiconductor chip 1. The bonding layer 7 is, for example, the same metal film as the back electrode 4 of the semiconductor chip. The back electrode 4 of the semiconductor chip 1 and the bonding layer 7 of the wiring chip 2 are respectively bonded to the substrate 3 via a bonding material 11.

[0030] A main electrode component 12 is bonded to the main electrode 5 of the semiconductor chip 1 via a first bonding material 13. The main electrode component 12 is made of copper, for example. When the main electrode component 12 straddles the main electrodes 5 of a plurality of semiconductor chips 1, the portion bonded to the main electrode 5 protrudes, and the portion connecting them is thinner than the portion bonded to the main electrode 5. Thus, it is possible to connect the main electrodes 5 of a plurality of semiconductor chips 1 at the same potential while avoiding the peripheral breakdown voltage structure of the semiconductor chip 1. Alternatively, the main electrodes 5 of a plurality of semiconductor chips 1 may be independent of each other and have a structure that becomes at the same potential when connected to an external electrode.

[0031] A control electrode component 14 is bonded to the second electrode 9 of the wiring chip 2 via a second bonding material 15. The control electrode component 14 is, for example, a plurality of blocks made of copper.

[0032] The control electrodes 6 of a plurality of semiconductor chips 1 and the first electrode 8 of the wiring chip 2 are connected by a connection component 16. The connection component 16 is, for example, a wire made of gold, silver, or aluminum. If a fine wire made of gold or silver is used, the size of the control electrode 6 of the semiconductor chip 1 can be reduced. Therefore, the effective area can be made larger, and the manufacturing cost of the semiconductor chip 1 can be reduced.

[0033] The semiconductor chip 1, the upper surface of the substrate 3, the wiring chip 2, the main electrode component 12, the control electrode component 14, and the connection component 16 are encapsulated by an encapsulation material 17. The encapsulation material 17 is, for example, a material obtained by mixing a filler into an epoxy resin. The front ends of the main electrode component 12 and the control electrode component 14 protrude from the upper surface of the encapsulation material 17, and the front faces are exposed from the encapsulation material 17.

[0034] Next, a method for manufacturing the semiconductor device according to this embodiment will be described. Figures 2 - 7 It is a cross-sectional view showing a method for manufacturing the semiconductor device according to Embodiment 1. First, as Figure 2As shown, the semiconductor chip 1 is bonded to the substrate 3. Next, as Figure 3 shown, the wiring chip 2 is bonded to the substrate 3. At this time, the back electrode 4 of the semiconductor chip 1 and the bonding layer 7 of the wiring chip 2 are respectively bonded to the substrate 3 via the bonding material 11. The bonding material 11 can be, for example, solder, or a bonding material made of silver or copper can be used for bonding by sintering bonding. The sintering bonding can be a pressure bonding in which pressure is applied to the electrodes from the upper surface while pressing the semiconductor chip 1 and the wiring chip 2 and heating up, or a non-pressure bonding without applying pressure. Alternatively, a thermomechanically stable adhesive or the like obtained by heating can be used to bond the wiring chip 2. However, in the case of using the wiring chip 2 made of silicon, the wiring chip 2 sometimes breaks, so a bonding method without applying pressure is preferably used.

[0035] Next, as Figure 4 shown, the main electrode component 12 is bonded to the main electrode 5 via the first bonding material 13. Next, as Figure 5 shown, the control electrode component 14 is bonded to the second electrode 9 via the second bonding material 15. The first bonding material 13 and the second bonding material 15 can be, for example, solder, or a bonding material made of silver or copper can be used for bonding by sintering bonding. The sintering bonding can be a pressure bonding in which pressure is applied to the electrodes from the upper surface while pressing and heating up, but a non-pressure bonding without applying pressure is preferably used.

[0036] Regarding the main electrode component 12 and the control electrode component 14, due to the fluctuations in their own manufacturing tolerances, the thicknesses of each fluctuate. In addition, the thicknesses of the first bonding material 13 and the second bonding material 15 also fluctuate. Therefore, the heights of the front end surfaces of the bonded main electrode component 12 and the control electrode component 14 are different.

[0037] Next, as Figure 6 shown, the control electrode 6 is connected to the first electrode 8 by the connecting component 16. Next, as Figure 7 shown, the semi-finished product having the bonded semiconductor chip 1, substrate 3, wiring chip 2, main electrode component 12, control electrode component 14, and connecting component 16 is placed in the mold 18. At this time, a buffer material 19 is provided between the main electrode component 12 and the control electrode component 14 and the mold 18.

[0038] If the front end faces of the main electrode member 12 and the control electrode member 14 are pressed against the buffer material 19, the thickness of the portion of the buffer material 19 that contacts the main electrode member 12 and the control electrode member 14 becomes thinner due to the pressing force. When the heights of the front end faces of the main electrode member 12 and the control electrode member 14 are different, the thickness of the buffer material 19 is different at the portion that contacts the main electrode member 12 and the portion that contacts the control electrode member 14. In this state, by the transfer molding encapsulation method of injecting the encapsulation material 17 into the mold 18, the semiconductor chip 1, the upper surface of the substrate 3, the wiring chip 2, the main electrode member 12, the control electrode member 14, and the connection member 16 are encapsulated by the encapsulation material 17.

[0039] When the semiconductor device is removed from the mold 18 after encapsulation, the buffer material 19 is also removed from the upper surface of the semiconductor device. Through the above processes, a semiconductor device in which the front end faces of the main electrode member 12 and the control electrode member 14 are exposed from the encapsulation material 17 is manufactured without grinding the encapsulation material 17.

[0040] In addition, if a plurality of manufactured semiconductor devices are used, an upper-level semiconductor device such as a half-bridge circuit or a full-bridge circuit can be constituted. In this case, the substrate 3 is electrically and thermally connected to the drain circuit pattern by solder bonding or sintering bonding. The main electrode member 12 is electrically connected to the source circuit pattern by wire bonding, tape bonding, or solder bonding of a lead frame. Then, the periphery of the semiconductor device and the circuit pattern are coated with a secondary encapsulation material such as gel to manufacture an upper-level semiconductor device. In addition, when solder is used as the bonding material for the semiconductor chip 1, it is preferable to use a high-melting-point solder whose melting point is higher than the bonding process temperature when assembling the upper-level semiconductor device.

[0041] Next, the effects of the present embodiment will be described by comparing with a comparative example. Figures 8 - 10 It is a cross-sectional view showing a method of manufacturing a semiconductor device according to a comparative example. In the comparative example, as Figure 8 shown, the buffer material 19 is not used in the resin encapsulation process. Therefore, a gap is generated between the mold 18 and the main electrode member 12 and the control electrode member 14, and the encapsulation material 17 infiltrates. Therefore, as Figure 9 shown, sometimes the main electrode member 12 or the control electrode member 14 cannot be exposed from the surface of the encapsulation material 17. Therefore, as Figure 10 shown, it is necessary to grind a part of the main electrode member 12 and the control electrode member 14 and the remaining encapsulation material 17 to expose the main electrode member 12 and the control electrode member 14.

[0042] In contrast, in the present embodiment, even if the heights of the control electrode member 14 and the main electrode member 12 fluctuate and a gap is generated between the main electrode member 12 and the control electrode member 14 and the mold 18, the buffer material 19 fills the gap. Therefore, in the encapsulation process, the front end surfaces of the main electrode member 12 and the control electrode member 14 are not covered by the encapsulation material 17 but are exposed. Therefore, the encapsulation material 17 is not ground after the encapsulation process. As a result, the manufacturing cost can be suppressed and the electrode member can be reliably led out from the upper surface of the device.

[0043] Figure 11 FIG. is a cross-sectional view showing the front end portion of the main electrode member after encapsulation. If the front end surfaces of the main electrode member 12 and the control electrode member 14 are pressed against the buffer material 19, the buffer material 19 in the portion in contact with the control electrode member 14 and the main electrode member 12 is thinner than the portion not in contact. The buffer material 19 gradually thins from the portion not in contact toward the portion in contact. Since resin encapsulation is performed in this state, the shape of the encapsulation material 17 follows the shape of the buffer material 19. Therefore, the encapsulation material 17 provided on the side surfaces of the front end portions of the main electrode member 12 and the control electrode member 14 has a tapered shape in which the film thickness in the lateral direction of the drawing becomes thinner as it approaches the front end surfaces of the main electrode member 12 and the control electrode member 14.

[0044] When there is a difference in the linear expansion coefficient between the main electrode member 12 and the control electrode member 14 and the linear expansion coefficient of the encapsulation material 17, stress is generated between the two due to thermal cycling or the like. If cracks are generated in the encapsulation material 17 or the encapsulation material 17 peels off due to the stress, moisture intrudes during a moisture resistance test or the like and reaches the semiconductor chip 1 or the like, reducing the life of the semiconductor device. In contrast, in the present embodiment, as described above, the film thickness of the encapsulation material 17 gradually thins as it approaches the front end surfaces of the main electrode member 12 and the control electrode member 14. Therefore, the stress is smaller as it approaches the end surfaces of the main electrode member 12 and the control electrode member 14, and thus, the encapsulation material 17 can be prevented from peeling off from the control electrode member 14 and the main electrode member 12.

[0045] In addition, when a temperature sensing element or a current sensing element is built in the semiconductor chip 1, these elements are mostly more susceptible to electrostatic influence than the main part. Therefore, it is preferable that the surface of the buffer material 19 in contact with the front end surfaces of the main electrode member 12 and the control electrode member 14 has conductivity. As a result, no potential difference is generated between the terminals from the encapsulation to after the encapsulation, and thus, overvoltage breakdown of the semiconductor chip 1 due to static electricity can be prevented.

[0046] Figure 12The figure is a cross-sectional view showing a modified example of the manufacturing method of the semiconductor device according to Embodiment 1. The buffer material 19 has a non-conductive encapsulation material 17 and a conductive thin film 20 such as a carbon sheet or a metal foil provided between the encapsulation material 17 and the main electrode member 12 and the control electrode member 14. The front end surfaces of the main electrode member 12 and the control electrode member 14 are in contact with the conductive thin film 20, and no potential difference is generated between the terminals. Therefore, overvoltage breakdown of the semiconductor chip 1 due to static electricity can be prevented. In addition, by using the conductive thin film 20, an inexpensive encapsulation material 17 such as Teflon can be used. Alternatively, the main component of the buffer material 19 may be carbon. Such a buffer material 19 has conductivity, and thus the buffer material 19 can be composed of a single component without using the conductive thin film 20. Therefore, the processing cost can be suppressed.

[0047] Embodiment 2

[0048] Figure 13 The figure is a cross-sectional view showing the semiconductor device according to Embodiment 2. In the present embodiment, there is no wiring chip 2 and connection member 16, and the control electrode member 14 is joined to the control electrode 6 of the semiconductor chip 1 via the second joining material 15. Other structures are the same as those in Embodiment 1.

[0049] Next, the manufacturing method of the semiconductor device according to the present embodiment will be described. Figures 14 - 16 The figure is a cross-sectional view showing the manufacturing method of the semiconductor device according to Embodiment 2. First, as Figure 14 shown, the semiconductor chip 1 is joined to the substrate 3. Next, as Figure 15 shown, the main electrode member 12 is joined to the main electrode 5 via the first joining material 13. The control electrode member 14 is joined to the control electrode 6 via the second joining material 15.

[0050] Next, as Figure 16 shown, the semi-finished product having the joined semiconductor chip 1, substrate 3, main electrode member 12, and control electrode member 14 is placed in the mold 18. At this time, a buffer material 19 is provided between the main electrode member 12, the control electrode member 14, and the mold 18. While pressing the front end surfaces of the main electrode member 12 and the control electrode member 14 against the buffer material 19, the encapsulation material 17 is injected into the mold 18, and the semiconductor chip 1, substrate 3, main electrode member 12, and control electrode member 14 are encapsulated with the encapsulation material 17.

[0051] When the semiconductor device is removed from the mold 18 after encapsulation, the buffer material 19 is also removed from the upper surface of the semiconductor device. Through the above process, a semiconductor device in which the front end surfaces of the main electrode member 12 and the control electrode member 14 are exposed from the encapsulation material 17 can be manufactured without grinding the encapsulation material 17. Thus, similarly to the first embodiment, the manufacturing cost can be suppressed and the electrode members can be reliably led out from the upper surface of the device. In the case of a small-capacity semiconductor product or the like where the number of semiconductor chips connected in parallel is small, this embodiment is sometimes preferable because it suppresses the manufacturing cost. In this embodiment, instead of using the wiring chip 2, the electrodes are individually led out from the semiconductor chip 1 and connected to an external circuit.

[0052] In addition, the semiconductor chip 1 is not limited to being formed of silicon, and may be formed of a wide-bandgap semiconductor having a larger bandgap than silicon. The wide-bandgap semiconductor is, for example, silicon carbide, a gallium nitride-based material, or diamond. Since a semiconductor chip formed of such a wide-bandgap semiconductor has high breakdown voltage and allowable current density, it can be miniaturized. By using the miniaturized semiconductor chip, the semiconductor device in which the semiconductor chip is assembled can also be miniaturized and highly integrated. In addition, since the semiconductor chip has high heat resistance, the heat dissipation fins of the radiator can be miniaturized and the water-cooling part can be air-cooled, so that the semiconductor device can be further miniaturized. In addition, since the semiconductor chip has low power loss and high efficiency, the semiconductor device can be made highly efficient.

[0053] Explanation of reference numerals

[0054] 1 Semiconductor chip, 2 Wiring chip, 3 Substrate, 5 Main electrode, 6 Control electrode, 8 First electrode, 9 Second electrode, 10 Wiring, 13 First bonding material, 15 Second bonding material, 16 Connecting member, 17 Encapsulation material, 18 Mold, 19 Buffer material, 20 Conductive film.

Claims

1. A method for manufacturing a semiconductor device, characterized in that, It has the following processes: Bond a semiconductor chip having a main electrode and a control electrode to a substrate; Bond a wiring chip having a first electrode, a second electrode, and a wiring connecting the first electrode and the second electrode to the substrate; Bond a main electrode component to the main electrode via a first bonding material; Bond a control electrode component to the second electrode via a second bonding material; Connect the control electrode and the first electrode through a connecting component; And Place the bonded semiconductor chip, substrate, wiring chip, main electrode component, control electrode component, and connecting component into a mold. While pressing the front end surfaces of the main electrode component and the control electrode component against a buffer material provided between the main electrode component, the control electrode component, and the mold, inject a packaging material into the mold, and encapsulate the semiconductor chip, substrate, wiring chip, main electrode component, control electrode component, and connecting component with the packaging material, Do not grind the packaging material, The front end parts of the main electrode component and the control electrode component protrude from the upper surface of the packaging material, The packaging material provided on the side surface of the front end part has a tapered shape with a thinner film thickness as it approaches the front end surface.

2. A method for manufacturing a semiconductor device, characterized in that, It has the following processes: Bond a semiconductor chip having a main electrode and a control electrode to a substrate; Bond a main electrode component to the main electrode via a first bonding material; Bond a control electrode component to the control electrode via a second bonding material; And Place the bonded semiconductor chip, substrate, main electrode component, and control electrode component into a mold. While pressing the front end surfaces of the main electrode component and the control electrode component against a buffer material provided between the main electrode component, the control electrode component, and the mold, inject a packaging material into the mold, and encapsulate the semiconductor chip, substrate, main electrode component, and control electrode component with the packaging material, Do not grind the packaging material, The front end parts of the main electrode component and the control electrode component protrude from the upper surface of the packaging material, The packaging material provided on the side surface of the front end part has a tapered shape with a thinner film thickness as it approaches the front end surface.

3. The manufacturing method of the semiconductor device according to claim 1 or 2, wherein The height of the front end surface of the bonded main electrode component is different from that of the front end surface of the control electrode component.

4. The manufacturing method of the semiconductor device according to claim 1 or 2, wherein The surface of the buffer material in contact with the front end surfaces of the main electrode component and the control electrode component has conductivity.

5. The manufacturing method of the semiconductor device according to claim 4, wherein The buffer material has a resin material and a conductive thin film provided between the resin material and the main electrode component and the control electrode component.

6. The manufacturing method of the semiconductor device according to claim 4, wherein The main component of the buffer material is carbon.

7. The manufacturing method of the semiconductor device according to claim 1 or 2, characterized in that the semiconductor chip is formed of a wide bandgap semiconductor.

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