Semiconductor Devices

Abstract

This semiconductor device comprises a semiconductor chip (10), and a thermistor (20) mounted on the semiconductor chip (10). The thermistor (20) is mounted on an insulating substrate (30) joined to the semiconductor chip (10), and the insulating substrate (30) provides insulation between the semiconductor chip (10) and the thermistor (20). On the insulating substrate (30), there are formed pattern wirings (31, 32) that draw electrodes (21, 22) of the thermistor (20) toward the outside of the thermistor (20) as seen in a plan view.

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor device. [Background technology]

[0002] In semiconductor devices used in inverters that control motors in electric vehicles, trains, etc., and in regenerative converters, the semiconductor elements generate heat due to current loss. Therefore, temperature-detecting thermistors are sometimes built in to prevent the semiconductor elements from shortening their lifespan and to protect the semiconductor elements from abnormal heat generation (for example, Patent Documents 1 and 2 listed below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2006 / 068082 [Patent Document 2] Japanese Utility Model Application Publication No. 01-044649 Summary of the Invention [Problem to be solved by the invention]

[0004] In the semiconductor device of Patent Document 1, a thermistor is soldered to the main electrodes of a semiconductor element. With this method, the potential of the thermistor's electrodes is the same as the potential of the main electrodes of the semiconductor element, which causes a problem in that noise is generated in the output signal of the thermistor due to fluctuations in the potential of the main electrodes that occur when a current flows through the semiconductor element.

[0005] On the other hand, in the semiconductor device of Patent Document 2, the thermistor is attached to the main electrode of the semiconductor element using an insulating adhesive. This method has problems with the reliability of insulation due to variations in the thickness of the adhesive, and also has the problem of making it difficult to wire bond to the electrode of the thermistor attached to the semiconductor element.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to ensure reliable insulation between the thermistor and the semiconductor element in a semiconductor device including a semiconductor element on which a thermistor is mounted, and to enable wire bonding to the electrodes of the thermistor attached to the semiconductor element. [Means for solving the problem]

[0007] A semiconductor device according to the present disclosure includes a semiconductor chip and a thermistor mounted on the semiconductor chip, the thermistor being mounted on an insulating substrate bonded to the semiconductor chip, the semiconductor chip and the thermistor being insulated from each other by the insulating substrate, pattern wiring is formed on the insulating substrate to draw electrodes of the thermistor to the outside of the thermistor in a plan view, and the thermistor is bonded to the insulating substrate so that its underside is in contact with the pattern wiring. Two pattern wirings are formed on the insulating substrate, each of which draws two electrodes of the thermistor to the outside of the thermistor in a plan view, and the size of the thermistor is smaller than the diameter of the wire joined to the pattern wirings. . [Effects of the Invention]

[0008] According to the present disclosure, the thickness of the insulating substrate is consistent, ensuring reliable insulation between the thermistor and the semiconductor element. In addition, the electrodes of the thermistor are drawn out by patterned wiring on the insulating substrate, allowing wire bonding to the electrodes of the thermistor.

[0009] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a plan view of a semiconductor device according to a first embodiment. [Figure 2] 1 is a cross-sectional view of a semiconductor device according to a first embodiment. [Figure 3] 1 is a top view of a thermistor mounted on a semiconductor device according to a first embodiment. [Figure 4] 10A and 10B are diagrams illustrating an example of the arrangement of first main electrodes of a semiconductor chip and a thermistor. [Figure 5] 10A and 10B are diagrams illustrating an example of the arrangement of first main electrodes of a semiconductor chip and a thermistor. [Figure 6] 1A and 1B are diagrams illustrating an example of an effective area of ​​a semiconductor chip and an arrangement of thermistors; [Figure 7] 1A and 1B are diagrams illustrating an example of an effective area of ​​a semiconductor chip and an arrangement of thermistors; [Figure 8] FIG. 10 is a plan view of a semiconductor device according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a semiconductor device according to a second embodiment. [Figure 10] FIG. 10 is a top view of a thermistor mounted on a semiconductor device according to a second embodiment. [Figure 11] FIG. 10 is a cross-sectional view of a semiconductor device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] <First Embodiment> 1 and 2 are diagrams showing the configuration of a semiconductor device according to embodiment 1, with Fig. 1 being a plan view of the semiconductor device and Fig. 2 being a side view of the semiconductor device. Note that in these figures, illustration of a molding resin that seals components of the semiconductor device is omitted.

[0012] In the semiconductor device according to the first embodiment, a semiconductor chip 10 having a semiconductor element formed thereon is mounted on a heat spreader 51, and the semiconductor chip 10 and the heat spreader 51 are joined together using solder 63, which is a brazing material. The heat spreader 51 is mounted on an insulating sheet 52 having metal foil 53 on its underside. The semiconductor device also includes a first main terminal 41, a second main terminal 42, and a plurality of signal terminals 43 as external connection terminals.

[0013] Here, the description will be given assuming that the semiconductor element formed on the semiconductor chip 10 is an IGBT (Insulated Gate Bipolar Transistor). However, the semiconductor element formed on the semiconductor chip 10 may be other elements, such as a MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) or a diode. The material of the semiconductor chip 10 may be silicon (Si), which has been conventionally used, or silicon carbide (SiC), which is a wide bandgap semiconductor. When the semiconductor chip 10 is formed using SiC, a semiconductor device superior in operation at high voltages, large currents, and high temperatures can be obtained compared to when the semiconductor chip 10 is formed using Si.

[0014] A first main electrode 11 serving as an emitter electrode, a control electrode 12 serving as a gate electrode, and a sense electrode 13 for detecting the emitter current are formed on the top surface of the semiconductor chip 10. The first main electrode 11 of the semiconductor chip 10 is joined to a first main terminal 41 using solder 61. The control electrode 12 and the sense electrode 13 of the semiconductor chip 10 are each connected to a signal terminal 43 using an aluminum wire 64. A second main terminal (not shown) serving as a collector electrode is formed on the bottom surface of the semiconductor chip 10, and the second main terminal is connected to a second main terminal 42 joined to the heat spreader 51 through solder 63 and the heat spreader 51.

[0015] A thermistor 20 for detecting temperature is mounted on the semiconductor chip 10. The thermistor 20 is mounted on an insulating substrate 30, which is joined to the first main electrode 11 of the semiconductor chip 10 using solder 62. In other words, the thermistor 20 is not directly attached to the semiconductor chip 10, but rather the insulating substrate 30 is interposed between the thermistor 20 and the semiconductor chip 10. Because there is little variation in the thickness of the insulating substrate 30, highly reliable insulation is ensured between the thermistor 20 and the semiconductor chip 10.

[0016] FIG. 3 shows an enlarged view of the thermistor 20 mounted on an insulating substrate 30. The thermistor 20 has a first electrode 21 on its upper surface and a second electrode (not shown) on its lower surface. A wiring pattern 32 is formed on the insulating substrate 30 in advance by printing, and the thermistor 20 is bonded to the insulating substrate 30 using brazing material so that the second electrode on the lower surface connects to the wiring pattern 32. The second electrode of the thermistor 20 is thus extended to the outside of the thermistor 20 in a planar view by the wiring pattern 32, and this wiring pattern 32 can be used as a bonding pad for wire bonding to the second electrode (i.e., for connecting an aluminum wire 64). The first electrode 21 is exposed on the upper surface of the thermistor 20, so direct wire bonding to the first electrode 21 is possible. The first electrode 21 of the thermistor 20 and the wiring pattern 32 are each connected to a signal terminal 43 using the aluminum wire 64.

[0017] Thermistor 20 and insulating substrate 30 are preferably bonded together prior to bonding insulating substrate 30 and semiconductor chip 10. In this case, thermistor 20 can be mounted on semiconductor chip 10 simply by soldering insulating substrate 30 to semiconductor chip 10 during the process of soldering a lead frame including first main terminal 41 and second main terminal 42 to semiconductor chip 10, thereby simplifying the assembly process of the semiconductor device.

[0018] The material of the insulating substrate 30 is preferably one with low thermal resistance so that heat generated in the semiconductor chip 10 can be easily transferred to the thermistor 20. For example, if AlN, a material with low thermal resistance, is used as the material of the insulating substrate 30, the accuracy of measuring the temperature of the semiconductor chip 10 can be improved.

[0019] Here, we will explain the main steps in the method for manufacturing the semiconductor device according to embodiment 1. The method for manufacturing the semiconductor device according to embodiment 1 includes the following die bonding step, frame joining step, wire bonding step, molding step, and lead processing step.

[0020] In the die bonding process, the semiconductor chip 10 is mounted on the heat spreader 51 using solder 63 .

[0021] In the frame joining process, the lead frame in which the first main terminal 41, the second main terminal 42 and the signal terminal 43 are integrated, and the insulating substrate 30 on which the thermistor 20 is mounted are joined to the semiconductor chip 10 using solder 61 and solder 62.

[0022] In the wire bonding process, aluminum wires 64 are ultrasonically bonded to the control electrodes 12 and sense electrodes 13 of the semiconductor chip 10, the first electrodes 21 of the thermistor 20, the pattern wiring 32 on the insulating substrate 30, and the signal terminals 43 of the lead frame.

[0023] In the molding process, first, the insulating sheet 52 and the sample that has undergone the wire bonding process are placed in the cavity of the mold die, and a resin pellet is placed in the pot. Next, the mold is heated to a high temperature, and the molten resin is pushed out of the pot with a plunger and poured into the cavity through a gate via a runner. The resin is then cured at a high temperature to seal the sample.

[0024] In the lead processing step, the resin-encapsulated sample is removed from the mold, and unnecessary resin and unnecessary parts such as the tie bars and frame of the lead frame are cut off by pressing or the like, and the first main terminal 41, second main terminal 42, signal terminal 43, etc. are processed into the desired shapes. This completes the semiconductor device.

[0025] Next, the operation of the semiconductor device according to the first embodiment will be described. When a voltage is applied to the signal terminal 43 connected to the control electrode 12, and the gate-emitter voltage of the IGBT, which is a semiconductor element formed on the semiconductor chip 10, exceeds a threshold value, the IGBT is turned on, and a current flows between the first main terminal 41 and the second main terminal 42. At this time, a loss occurs due to the internal resistance of the IGBT, and the semiconductor chip 10 generates heat. A signal corresponding to the temperature of the semiconductor chip 10 is output between the first electrode 21 and the second electrode 22 of the thermistor 20. The output signal from the thermistor 20 can be used to control a protection circuit that protects the semiconductor chip 10, for example.

[0026] As described above, in the semiconductor device of embodiment 1, an insulating substrate 30 with little variation in thickness is interposed between the thermistor 20 and the semiconductor chip 10, thereby ensuring highly reliable insulation between the thermistor 20 and the semiconductor chip 10.

[0027] Furthermore, the second electrode on the underside of the thermistor 20 is extended to the outside of the thermistor 20 in plan view by the pattern wiring 32 on the insulating substrate 30. By using this pattern wiring 32 as a bonding pad, the second electrode of the thermistor 20 can be wire-bonded in the same way as the first electrode of the thermistor 20 and the control electrode 12 and sense electrode 13 of the semiconductor chip 10. This allows for simultaneous wiring to multiple signal terminals 43, contributing to the simplification and efficiency of the assembly process. Furthermore, it is possible to inspect the thermistor 20 and insulating substrate 30 before attaching them to the semiconductor chip 10, which also leads to reduced loss costs.

[0028] Furthermore, because the thermistor 20 is insulated from the semiconductor chip 10 by the insulating substrate 30, the thermistor 20 may be placed anywhere on the semiconductor chip 10, which also provides the advantage of increasing the degree of freedom in layout design. In this embodiment, an example is shown in which the thermistor 20 is placed on the first main electrode 11 of the semiconductor chip 10 as shown in Fig. 4, but the thermistor 20 may also be placed outside the first main electrode 11 as shown in Fig. 5, for example.

[0029] Furthermore, because the thermistor 20 is not affected by the current flowing through the first main electrode 11 of the semiconductor chip 10, it is not necessary to place the thermistor 20 outside the active area 15 of the semiconductor chip 10 where the semiconductor elements are formed, as shown in FIG. 6 . That is, the active area 15 of the semiconductor chip 10 may extend below the position where the thermistor 20 is mounted, as shown in FIG. 7 . By extending the active area 15 below the thermistor 20, the internal resistance of the semiconductor chip 10 can be reduced, and heat generation can be suppressed. In addition, being able to extend the active area 15 means that the size of the semiconductor chip 10 can be reduced while maintaining the area of ​​the active area 15. In particular, when SiC is used as the material for the semiconductor chip 10, because SiC has a higher cost per area than Si, reducing the size of the semiconductor chip 10 can significantly contribute to cost reduction.

[0030] Furthermore, because the thermistor 20 is insulated from the semiconductor chip 10, even when the semiconductor device according to the first embodiment is used in a circuit on the high-voltage side of an inverter, the output signal of the thermistor 20 can be input directly to a circuit on the low-voltage side (for example, an ECU (Electronic Control Unit)) without being isolated by a coupler, etc. This can contribute to preventing transmission delays in the output signal of thermistor 20 and reducing the circuit area of ​​the inverter.

[0031] <Embodiment 2> 8 and 9 are diagrams showing the configuration of a semiconductor device according to a second embodiment, where Fig. 8 is a plan view of the semiconductor device and Fig. 9 is a side view of the semiconductor device. Figure 10 10 shows an enlarged view of a thermistor 20 mounted on an insulating substrate 30 in a semiconductor device according to a second embodiment.

[0032] In the first embodiment, only the pattern wiring 32 connected to one (the second electrode) of the two electrodes of the thermistor 20 is formed on the insulating substrate 30. In contrast, in the second embodiment, the pattern wiring 31 connected to the first electrode 21 of the thermistor 20 and the pattern wiring 32 connected to the second electrode 22 of the thermistor 20 are formed on the insulating substrate 30. The aluminum wire 64 connected to the first electrode 21 is joined to the pattern wiring 31, and the aluminum wire 64 connected to the second electrode 22 is joined to the pattern wiring 32. The other configurations are the same as those in the first embodiment.

[0033] In the semiconductor device according to the second embodiment, the first electrode 21 and the second electrode 22 of thermistor 20 are respectively drawn out to the outside of thermistor 20 in a plan view by pattern wiring 31 and pattern wiring 32, and these pattern wirings 31 and pattern wiring 32 can be used as bonding pads to perform wire bonding to first electrode 21 and second electrode 22. This is effective when it is difficult to directly wire bond to first electrode 21 and second electrode 22 of thermistor 20, for example, when thermistor 20 is smaller than the diameter of aluminum wire 64.

[0034] <Third Embodiment> 11 is a diagram showing the configuration of a semiconductor device according to embodiment 2, illustrating a side view of the semiconductor device. The top view of the semiconductor device is the same as FIG. 2. The configurations of insulating substrate 30 and thermistor 20 may be either those shown in FIG. 3 or FIG. 10.

[0035] In the first and second embodiments, the insulating substrate 30 carrying the thermistor 20 and the semiconductor chip 10 are joined together by solder 62. In contrast, in the third embodiment, the insulating substrate 30 and the semiconductor chip 10 are joined together by a bonding material 65 made of silver (Ag) (hereinafter referred to as "Ag bonding material 65"). The other configurations are the same as those of the first or second embodiment.

[0036] Ag has low thermal resistance and is less susceptible to void generation, so by bonding the insulating substrate 30 and the semiconductor chip 10 with the Ag bonding material 65, the accuracy of measuring the temperature of the semiconductor chip 10 can be improved.

[0037] The above description is illustrative in all respects, and it is understood that countless variations not illustrated can be envisioned. [Explanation of symbols]

[0038] 10 semiconductor chip, 11 first main electrode, 12 control electrode, 13 sense electrode, 15 effective area, 20 thermistor, 21 first electrode, 22 second electrode, 30 insulating substrate, 31 pattern wiring, 32 pattern wiring, 41 first main terminal, 42 second main terminal, 43 signal terminal, 51 heat spreader, 52 insulating sheet, 53 metal foil, 61, 62, 63 solder, 64 aluminum wire, 65 Ag bonding material.

Claims

1. A semiconductor chip; a thermistor mounted on the semiconductor chip; Equipped with the thermistor is mounted on an insulating substrate bonded to the semiconductor chip, and the semiconductor chip and the thermistor are insulated from each other by the insulating substrate; pattern wiring is formed on the insulating substrate to draw electrodes of the thermistor to the outside of the thermistor in a plan view, the thermistor is bonded to the insulating substrate so that a lower surface of the thermistor is in contact with the pattern wiring; two pattern wirings are formed on the insulating substrate, each of which leads two electrodes of the thermistor to the outside of the thermistor in a plan view; The size of the thermistor is smaller than the diameter of the wire bonded to the pattern wiring. Semiconductor device.

2. The effective area of ​​the semiconductor chip extends to below the position where the thermistor is mounted. The semiconductor device according to claim 1 .

3. The semiconductor chip is formed using SiC.

3. The semiconductor device according to claim 1.

4. the semiconductor chip and the insulating substrate are bonded together with a bonding material containing Ag; The semiconductor device according to claim 1 .

5. the insulating substrate is formed of AlN; The semiconductor device according to claim 1 .

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