JP2019192671A - Semiconductor device - Google Patents

Abstract

To suppress variations in electric characteristics of a temperature sense diode built into a semiconductor device.SOLUTION: A semiconductor device disclosed in the present specification comprises a semiconductor element including a temperature sense diode, a conductor plate arranged with the semiconductor element, and a sealing body integrally holding the semiconductor element and the conductor plate. In this semiconductor device, when viewed in a thickness direction of the sealing body, the semiconductor element is arranged so that a direction of current flowing in the temperature sense diode inclines to each side of a rectangular outer peripheral edge of the sealing body.SELECTED DRAWING: Figure 2

Description

  The technology disclosed in this specification relates to a semiconductor device.

  Patent Document 1 discloses a semiconductor device. The semiconductor device includes a semiconductor element having a temperature sensing diode, a conductor plate on which the semiconductor element is disposed, and a sealing body that integrally holds the semiconductor element and the conductor plate.

Japanese Patent Laid-Open No. 2006-146428

  The sealing body of the semiconductor device described above is made of a thermosetting resin and is molded using a mold. Since the thermosetting resin is molded and cured at a high temperature, thermal shrinkage occurs in the sealed body after the molding as the temperature decreases thereafter. At this time, since the linear expansion coefficients are greatly different among the sealing body, the conductor plate, and the semiconductor element, a relatively large compressive stress acts on the semiconductor element disposed inside the sealing body. Usually, since the sealing body has a rectangular plate shape in accordance with the conductor plate, the semiconductor element located inside thereof strongly acts in a direction parallel to the plate-shaped sealing body.

  Generally, since the temperature sensing diode is located near the center of the semiconductor element, the compressive stress applied to the semiconductor element from the sealing body acts strongly on the temperature sensing diode. When compressive stress acts on the temperature sensing diode, a change occurs in the electrical characteristics (eg, forward voltage) of the temperature sensing diode due to the piezoresistive effect. Here, inevitable variations (individual differences) in manufacturing exist in the electrical characteristics of the temperature sensing diode from the beginning. When the variation due to the compressive stress described above is further added to this variation, the variation in the electrical characteristics of the temperature sensing diode can be further increased at the stage of incorporation into the semiconductor device. The present specification provides a technique capable of suppressing such variation in electrical characteristics.

  A semiconductor device disclosed in this specification includes a semiconductor element having a temperature sensing diode, a conductor plate on which the semiconductor element is disposed, and a sealing body that integrally holds the semiconductor element and the conductor plate. In this semiconductor device, when viewed in plan along the thickness direction of the sealing body, the direction of the current flowing in the temperature sensing diode is inclined with respect to each side of the rectangular outer peripheral edge of the sealing body. A semiconductor element is arranged.

  As described above, when compressive stress acts on the temperature sensing diode, the electrical characteristics of the temperature sensing diode change due to the piezoresistance effect. The degree of change in the electrical characteristics varies not only according to the magnitude of the compressive stress but also depending on the direction in which the compressive stress acts. In particular, when the direction of the compressive stress acting on the temperature sensing diode is perpendicular to the direction of the current flowing in the temperature sensing diode, a change that occurs in the electrical characteristics of the temperature sensing diode becomes large. Further, since the shape of the sealing body is, for example, a rectangular plate shape and not a symmetric shape such as a spherical shape, the compressive stress generated inside the sealing body has anisotropy, and its size Changes depending on the direction.

  In the technology disclosed in this specification, variations in electrical characteristics of the temperature sensing diode are suppressed by using these relationships in combination. Specifically, the direction of the temperature sensing diode in the sealed body is individually determined according to the actual electrical characteristics of the temperature sensing diode. That is, if the direction of the temperature sensing diode in the sealing body is changed, the direction in which the compressive stress acts on the temperature sensing diode changes, so that the change that occurs in the electrical characteristics of the temperature sensing diode can be adjusted. . Therefore, if the orientation of the temperature sensing diode to be arranged in the sealed body is individually determined according to the existing individual differences in manufacturing of the electrical characteristics of the temperature sensing diode, the change in the electrical characteristics caused by the compressive stress The individual differences in manufacturing can be offset. As a result, in the semiconductor device disclosed in the present specification, when viewed in plan along the thickness direction of the sealing body, the direction of the current flowing in the temperature sensing diode is that of the rectangular outer peripheral edge of the sealing body. A semiconductor element may be arranged to be inclined with respect to each side.

FIG. 3 is a cross-sectional view showing the internal structure of the semiconductor device 10 according to the first embodiment. Sectional drawing in the II-II line of FIG. 4 is a flowchart of a method for manufacturing the semiconductor device 10. A process of assembling the semiconductor device 10 based on the determined mounting angle θ of the temperature sensing diode 20 with respect to the compressive stress F applied to the semiconductor device 10 will be described. The frequency distribution of the forward voltage of the temperature sensing diode 20 is shown. The mounting angle θ of the temperature sensing diode 20 with respect to the trimming amount ΔV of the forward voltage of the temperature sensing diode 20 is shown. The degree of change in forward voltage that occurs with respect to the mounting angle θ of the temperature sensing diode 20 is shown. FIG. 6 is a cross-sectional view illustrating an internal structure of a semiconductor device 100 according to a second embodiment.

  With reference to FIGS. 1-7, the semiconductor device 10 of Example 1 and its manufacturing method are demonstrated. As shown in FIG. 1, the semiconductor device 10 includes a semiconductor element 12, a conductor spacer 14, an upper conductor plate 16, a lower conductor plate 18, and a sealing body 30. The semiconductor element 12 is sealed inside the sealing body 30. The sealing body 30 is made of a thermosetting resin such as an epoxy resin.

  The semiconductor element 12 has an emitter electrode 12a and a collector electrode 12b. The emitter electrode 12 a is located on the upper surface of the semiconductor element 12, and the collector electrode 12 b is located on the lower surface of the semiconductor element 12. As an example, the semiconductor element 12 may be an IGBT (Insulated Gate Bipolar Transistor) element. However, the semiconductor element 12 is not particularly limited to the IGBT element, and may be another power semiconductor element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) element. The semiconductor element 12 can be configured using various semiconductor materials such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN). The material constituting the emitter electrode 12a and the collector electrode 12b is not particularly limited, and for example, aluminum or other metals can be adopted.

  The conductive spacer 14 can be configured using a conductive material such as copper or other metal. The conductor spacer 14 is a generally plate-shaped or block-shaped member, and has an upper surface 14a and a lower surface 14b located on the opposite side of the upper surface 14a. The lower surface 14 b of the conductor spacer 14 is joined to the emitter electrode 12 a of the semiconductor element 12 via the solder layer 34. An upper surface 14 a of the conductor spacer 14 is joined to a lower surface 16 b of the upper conductor plate 16 described later via a solder layer 32. Thereby, the conductor spacer 14 is electrically connected to the semiconductor element 12. The conductor spacer 14 is not necessarily required, but ensures a space for connecting a plurality of first signal terminals 26 and a plurality of second signal terminals 28 described later to the semiconductor element 12.

  The upper conductor plate 16 and the lower conductor plate 18 can be configured using a conductive material such as copper or other metal. The upper conductor plate 16 is, for example, a generally plate-shaped or rectangular parallelepiped member, and has an upper surface 16a and a lower surface 16b positioned on the opposite side of the upper surface 16a. As described above, the lower surface 16 b of the upper conductor plate 16 is joined to the upper surface 14 a of the conductor spacer 14 via the solder layer 32. Thus, the upper conductor plate 16 is electrically connected to the conductor spacer 14 and is electrically connected to the semiconductor element 12 via the conductor spacer 14. In the present embodiment, although it is an example, the upper surface 16 a of the upper conductor plate 16 is exposed to the outside of the sealing body 30.

  The lower conductor plate 18 is, for example, a generally plate-shaped or rectangular parallelepiped member, and has an upper surface 18a and a lower surface 18b located on the opposite side of the upper surface 18a. The upper surface 18 a of the lower conductor plate 18 is joined to the collector electrode 12 b of the semiconductor element 12 via the solder layer 36. Thereby, the lower conductor plate 18 is electrically connected to the semiconductor element 12. In this embodiment, although it is an example, the lower surface 18 b of the lower conductor plate 18 is exposed to the outside of the sealing body 30. The upper conductor plate 16 and the lower conductor plate 18 are also thermally connected to the semiconductor element 12 and function as a heat radiating plate that releases the heat generated in the semiconductor element 12 to the outside. That is, the semiconductor device 10 of this embodiment has a double-sided cooling structure in which the heat sink is exposed on both sides of the sealing body 30. However, the semiconductor device 10 is not limited to the double-sided cooling structure, and for example, one of the upper surface 16 a of the upper conductor plate 16 and the lower surface 18 b of the lower conductor plate 18 is exposed to the outside of the sealing body 30. It may have a single-sided cooling structure.

  As shown in FIG. 2, the semiconductor device 10 includes a plurality of first signal terminals 26 and a plurality of second signal terminals 28. The plurality of first signal terminals 26 and the plurality of second signal terminals 28 extend from the outside to the inside of the sealing body 30 and are electrically connected to the semiconductor element 12 inside the sealing body 30. Yes.

  The semiconductor element 12 of the semiconductor device 10 further includes a temperature sensing diode 20. The temperature sensing diode 20 is located near the center of the upper surface of the semiconductor element 12. In addition, in the semiconductor device 10, when viewed in plan along the thickness direction of the sealing body 30, the direction of the current flowing in the temperature sensing diode 20 is on each side of the rectangular outer periphery of the sealing body 30. The semiconductor element 12 is disposed so as to be inclined with respect to the semiconductor element 12. The temperature sensing diode 20 is made of polysilicon, for example. The temperature sensing diode 20 includes a p-type semiconductor layer 20p and an n-type semiconductor layer 20n. The temperature sensing diode 20 has an anode electrode 20a on the p-type semiconductor layer 20p and a cathode electrode 20c on the n-type semiconductor layer 20n. The anode electrode 20a and the cathode electrode 20c of the temperature sensing diode 20 are made of, for example, aluminum or polysilicon.

  The semiconductor element 12 of the semiconductor device 10 further includes a p-type signal pad 22 and an n-type signal pad 24. The material constituting the p-type signal pad 22 and the n-type signal pad 24 is not particularly limited. For example, an aluminum-based or other metal is used. The p-type signal pad 22 is connected to a plurality of first signal terminals 26 using bonding wires 27. The n-type signal pad 24 is connected to the plurality of second signal terminals 28 using bonding wires 29.

  The temperature sensing diode 20 generates a forward voltage when a constant current flows from the p-type semiconductor layer 20p to the n-type semiconductor layer 20n. This forward voltage has a strong correlation with temperature, and the forward voltage decreases as the temperature of the temperature sensing diode 20 increases. As described above, the temperature sensing diode 20 is located near the center of the upper surface of the semiconductor element 12. Therefore, the temperature of the temperature sensing diode 20 substantially matches the temperature of the semiconductor element 12. Thereby, the temperature of the semiconductor element 12 can be detected using the temperature sensing diode 20.

  The sealing body 30 of the semiconductor device 10 according to the present embodiment is made of a thermosetting resin and is molded using a mold. Since the thermosetting resin is molded and cured at a high temperature, thermal shrinkage occurs in the molded body 30 after the molding as the temperature decreases thereafter. At this time, the linear expansion coefficients are greatly different between the sealing body 30, the conductor plates 16 and 18, and the semiconductor element 12, so that the semiconductor element 12 disposed inside the sealing body 30 is relatively A large compressive stress acts. Since the sealing body 30 has a rectangular plate shape in accordance with the conductor plates 16 and 18, the semiconductor element 12 located inside thereof strongly acts in a direction parallel to the plate-shaped sealing body 30.

  As described above, since the temperature sensing diode 20 is located near the center of the semiconductor element 12, the compressive stress applied to the semiconductor element 12 from the sealing body 30 acts strongly on the temperature sensing diode 20. When compressive stress acts on the temperature sensing diode 20, a change occurs in the electrical characteristics (eg, forward voltage) of the temperature sensing diode 20 due to the piezoresistive effect. Here, in the electrical characteristics of the temperature sensing diode 20, inevitable variations in manufacturing (individual differences) exist from the beginning. If the variation due to the compressive stress described above is further added to this variation, the variation in the electrical characteristics of the temperature sensing diode 20 can be further increased at the stage of incorporation into the semiconductor device 10.

  As described above, when compressive stress acts on the temperature sensing diode 20, the electrical characteristics of the temperature sensing diode 20 change due to the piezoresistance effect. The degree of change in the electrical characteristics varies not only according to the magnitude of the compressive stress but also depending on the direction in which the compressive stress acts. In particular, when the direction of the compressive stress acting on the temperature sensing diode 20 is perpendicular to the direction of the current flowing through the temperature sensing diode 20, a change that occurs in the electrical characteristics of the temperature sensing diode 20 becomes large. Moreover, since the shape of the sealing body 30 is, for example, a rectangular plate, and not a symmetric shape such as a spherical shape, the compressive stress generated inside the sealing body 30 has anisotropy. The size changes depending on the direction.

  In the semiconductor device 10 of the present embodiment, variations in electrical characteristics of the temperature sensing diode 20 are suppressed by using these relationships in combination. Specifically, the orientation of the temperature sensing diode 20 in the sealing body 30 is individually determined according to the actual electrical characteristics of the temperature sensing diode 20. That is, if the direction of the temperature sensing diode 20 in the sealing body 30 is changed, the direction in which the compressive stress is strongly applied to the temperature sensing diode 20 changes. Can be adjusted. Therefore, if the orientation of the temperature sensing diode 20 disposed in the sealing body 30 is individually determined according to the existing individual differences in manufacturing of the electrical characteristics of the temperature sensing diode 20, the electricity caused by the compressive stress is generated. Due to the change in characteristics, existing individual differences in manufacturing can be offset. As a result, in the semiconductor device 10 according to the present embodiment, the direction of the current flowing in the temperature sensing diode 20 is outside the rectangular shape of the sealing body 30 when viewed in plan along the thickness direction of the sealing body 30. The semiconductor element 12 is arranged so as to be inclined with respect to each side of the periphery.

Next, a method for manufacturing the semiconductor device 10 according to the first embodiment will be described with reference to FIGS. However, here, in particular, a series of steps for determining the mounting angle θ of the temperature sensing diode 20 as shown in FIG. 4 will be described. Here, the case where the temperature sensing diode 20 is arranged in parallel to the longitudinal direction of the sealing body 30 formed in a later process is defined as a reference position, and the rotation direction from the reference position with the center of the temperature sensing diode 20 as a base point. The angle rotated in this way is called the mounting angle θ. About the process of forming another component, it can form using various well-known methods suitably. Here, as an example, the used temperature sensing diode 20 has the following properties. At the stage of incorporation into the semiconductor device 10, the forward voltage distribution x of the temperature sensing diode 20 is displaced by, for example, −30 mV and shifted to the distribution y (ie, the offset value V _OFFSET = 30). Further, at the stage of being incorporated in the semiconductor device 10, the forward voltage distribution x of the temperature sensing diode 20 is displaced from ± 10 mV to ± 15 mV, for example (see FIG. 5). However, the forward voltage referred to here is an example of electrical characteristics in the temperature sensing diode 20.

  First, in step S12, the forward voltage of each temperature sensing diode 20 is measured. As described above, the forward voltage of the temperature sensing diode 20 has inevitable manufacturing variations (individual differences). Therefore, in order to determine the mounting angle θ of the temperature sensing diode 20, it is necessary to grasp in advance the variation in the forward voltage of the temperature sensing diode 20. Here, when the measured forward voltage distribution x of the plurality of temperature sensing diodes 20 is 1350 ± 10 mV, the distribution x is displaced to the distribution y at the stage of being incorporated in the semiconductor device 10, and the distribution y is It is estimated to be 1320 + 15 mV.

Next, in step S14, the trimming amount ΔV of each temperature sensing diode 20 is calculated. Here, trimming refers to adjusting the estimated distribution y to a desired distribution z (an ideal value of the forward voltage) (that is, reducing variations in the forward voltage) at the stage of incorporation into the semiconductor device 10. Point to. First, an ideal value (average value of distribution z) to be adjusted by trimming is set. The ideal value of the forward voltage is determined by the following equation.
Ideal value = average value of distribution y + offset value V _OFFSET / 2
In this embodiment, the ideal value = 1320 (mV) +30 (mV) / 2 = 1335 (mV). Next, the trimming amount ΔV is calculated by the following equation.
Trimming amount ΔV = ideal value− (each measured value−offset value V _OFFSET )
If the forward voltage of the temperature sensing diode 20 measured in the previous step S12 is 1345 mV, the trimming amount ΔV = 1335− (1345-30) = 20 (mV) is calculated.

  Next, in step S16, the mounting angle θ of the temperature sensing diode is determined. The mounting angle θ can be obtained from the trimming amount ΔV obtained above with reference to FIG. Therefore, in this embodiment, since the trimming amount ΔV is 20 mV, the mounting angle θ of the temperature sensing diode 20 is determined to be 20 °.

  As shown in FIG. 4, in step S18, the semiconductor device 10 is assembled based on the determined mounting angle θ. The shape of the sealing body 30 is, for example, a rectangular plate shape, and is not a symmetric shape such as a spherical shape. Therefore, the compressive stress generated inside the sealing body 30 has anisotropy, and its magnitude changes depending on the direction. In particular, in this embodiment, a large compressive stress F is generated at each side in the longitudinal direction of the outer peripheral edge of the sealing body 30. Even in such a case, the compressive stress F is strongly applied to the temperature sensing diode 20 by changing the direction (mounting angle θ) of the temperature sensing diode 20 in the sealing body 30 formed in a later process. A change occurring in the forward voltage of the temperature sensing diode 20 can be adjusted using the fact that the acting direction changes (see FIG. 7). Therefore, if the direction (mounting angle θ) of the temperature sensing diode 20 disposed in the sealing body 30 is individually determined in accordance with the existing individual manufacturing difference in the forward voltage of the temperature sensing diode 20, Due to the change in the forward voltage caused by the compressive stress F, existing individual manufacturing differences can be offset. In other words, variations in the forward voltage of the temperature sensing diode 20 incorporated in the semiconductor device 10 can be suppressed.

  In the semiconductor device 10 of this embodiment, the temperature sensing diode 20 is fixed on the semiconductor element 12. Therefore, the mounting direction of the semiconductor element 12 is changed in order to arrange the temperature sensing diode 20 in accordance with the determined mounting angle θ. As a result, each side of the rectangular outer periphery of the semiconductor element 12 is inclined with respect to each side of the rectangular outer periphery of the sealing body 30. However, these positional configurations are not limited to the configurations of the present embodiment. When viewed in plan along the thickness direction of the sealing body 30, the direction of the current flowing in the temperature sensing diode 20 is inclined with respect to each side of the rectangular outer peripheral edge of the sealing body 30. It is only necessary that the element 12 is arranged. For example, even if the sealing body 30 and the semiconductor element 12 are fixed integrally, and the temperature sensing diode 20 is rotated alone according to the determined mounting angle θ and tilted with respect to the sealing body 30. Good.

  With reference to FIG. 8, the semiconductor device 100 of Example 2 is demonstrated. The semiconductor device 100 is different from the semiconductor device 10 of the first embodiment in that the semiconductor element 112 includes a plurality of p-type signal pads 122 and a plurality of n-type signal pads 124. Therefore, only the configuration related to the plurality of p-type signal pads 122 and n-type signal pads 124 will be described here. Other configurations in the second embodiment are the same as those in the first embodiment, and a description thereof is omitted.

  As described above, in the semiconductor device 100 of this embodiment, the semiconductor element 112 has a plurality of p-type signal pads 122 and a plurality of n-type signal pads 124. The material constituting the plurality of p-type signal pads 122 and the plurality of n-type signal pads 124 is not particularly limited. For example, aluminum-based or other metals are employed. The plurality of p-type signal pads 122 are arranged on an arc with the temperature sensing diode 20 as the center. The plurality of n-type signal pads 124 are also arranged on an arc around the temperature sensing diode 20. As in the first embodiment, the p-type signal pad 122 is connected to the plurality of first signal terminals 26, and the n-type signal pad 124 is connected to the plurality of second signal terminals 28. According to the configuration described above, even when the semiconductor element 112 is arranged in various orientations, the signal terminals 26 and 28 are connected to the p-type signal pad 122 or the n-type signal pad 124 located relatively close to each other. be able to. Thereby, the mounting angle of the temperature sensing diode 20 can be changed without requiring significant adjustment or change of wire bonding.

  The dimensions (radius and center angle) of the arc in which the plurality of p-type signal pads 122 and the plurality of n-type signal pads 124 are arranged are not particularly limited, and the plurality of p-type signal pads 122 and the plurality of n-type signals are used. The signal pads 124 may be arranged on concentric circles.

  Several specific examples have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations.

10, 100: Semiconductor device 12, 112: Semiconductor element 12a: Emitter electrode 12b: Collector electrode 14: Conductor spacer 16: Upper conductor plate 18: Lower conductor plate 20: Temperature sensing diode 20a: Anode electrode 20c: Cathode electrode 20n : N-type semiconductor layer 20p: p-type semiconductor layer 22, 122: p-type signal pad 24, 124: n-type signal pad 26: first signal terminal 27, 29: bonding wire 28: second signal terminal 30: sealed Stop body 32, 34, 36: Solder layer F: Compressive stress x: Measurement distribution of forward voltage of temperature sensing diode y: Estimated distribution of forward voltage of temperature sensing diode incorporated in semiconductor device z: Semiconductor device Ideal distribution of forward voltage ΔV: trimming amount θ: mounting angle of temperature sensing diode

Claims (1)

A semiconductor element having a temperature sensing diode;
A conductor plate on which the semiconductor element is disposed;
A sealing body that integrally holds the semiconductor element and the conductor plate;
With
When viewed in plan along the thickness direction of the sealing body, the direction of the current flowing in the temperature sensing diode is inclined with respect to each side of the rectangular outer peripheral edge of the sealing body. Semiconductor elements are arranged,
Semiconductor device.

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