JPWO2015029511A1 - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

The present invention provides a semiconductor device having high heat transfer and excellent workability, and a method for manufacturing the same. The present invention includes an insulating substrate 13, a semiconductor chip 11 provided on the insulating substrate, and a cooling member 12 bonded to the back surface of the insulating substrate via a bonding material 23. The insulating substrate includes an insulating plate (6), and a conductive plate 5 and a conductive plate 7 provided on both surfaces of the insulating plate. The cooling member is a composite member in which the thermal stress absorbing member 1 made of aluminum and the heat conducting metal member 2 are integrated. The thermal stress absorbing member is disposed on the side to be bonded to the back surface of the insulating substrate, and the yield stress of the thermal stress absorbing member is smaller than the yield stress of the bonding material.

Description

  The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device, and more particularly to a semiconductor device that requires heat dissipation and a method for manufacturing the semiconductor device.

  In a semiconductor device (power module) using a semiconductor chip such as an IGBT (Insulated Gate Bipolar Transistor), it is necessary to efficiently dissipate heat generated from the semiconductor chip to keep the temperature of the semiconductor chip below a predetermined temperature.

  Conventionally, a conductive plate made of a highly thermally conductive insulating ceramic plate such as silicon nitride, aluminum nitride, or alumina, and a highly thermally conductive metal such as aluminum or copper (including the same alloy, hereinafter the same) provided on both surfaces thereof. The semiconductor chip is bonded to one surface of a so-called insulating substrate integrated with solder via a bonding material such as solder, and the cooler is directly or indirectly connected to the other surface of the insulating substrate via a bonding material such as solder. There is a power module that is joined.

  However, depending on the use conditions, thermal stress is generated due to the difference in thermal expansion coefficient between the insulating substrate and the cooler, and a crack is generated in the bonding material that joins the insulating substrate and the cooler. In some cases, sufficient heat dissipation performance could not be maintained during the lifetime.

  Therefore, in order to solve such a problem, a proposal has been made to dispose a stress relaxation member between an insulating substrate and a cooler (for example, Patent Document 1).

  The stress relaxation member in Patent Document 1 is made of an aluminum plate having a thickness of 0.3 to 3 mm in which a plurality of through holes are formed. Each through hole of the stress relaxation member is a stress absorbing space. The stress relaxation member is brazed to the insulating substrate and the heat sink. The stress relieving member is deformed by the action of the stress absorbing space, thereby relieving the thermal stress.

JP 2006-294699 A

  However, a semiconductor device including a stress relaxation member having a stress absorption space as in Patent Document 1 has two major problems.

  The first is a heat transfer problem. The average heat transfer coefficient of the stress relaxation member is lower than the average heat transfer coefficient of the base material. This is because the stress absorption space of the stress relaxation member is air, and its heat transfer coefficient is extremely low, so that, on average, the heat transfer coefficient of the base material is lowered by the volume ratio of the stress absorption space. . Moreover, the spread of heat flow is not good in the stress relaxation member having a thickness of preferably 1 to 4 mm. This is because the heat flow is disturbed by the stress absorption space. Further, a brazing material having a heat transfer coefficient lower than that of the base material is used for the connection portion between the insulating substrate and the heat sink. However, since the number of the connection portions is large, the overall thermal resistance is increased.

  The second problem is workability. The stress relaxation member and the insulating substrate cannot be brazed in a state where the semiconductor chip is mounted on the insulating substrate because of the processing temperature. That is, it is necessary to perform die bonding and further wire bonding of the semiconductor chip in the state of the substrate ASSY product (collective component) in which the cooler, the stress relaxation member, and the insulating substrate are integrated. At the time of die bonding and wire bonding, it is desirable that the insulating substrate is completely fixed, but it is difficult to obtain sufficient rigidity between the cooler and the stress relaxation member because of its structure. Therefore, for example, in a process that requires pressurization, the insulating substrate or chip is cracked and broken. For example, in a processing process using ultrasonic waves, problems such as non-adherence due to ultrasonic loss occur.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a semiconductor device having high heat transfer and excellent workability, and a method for manufacturing the same.

  A semiconductor device according to one embodiment of the present invention includes an insulating substrate including an insulating plate and a conductive plate provided on both surfaces of the insulating plate, a semiconductor chip provided on the insulating substrate, and a back surface of the insulating substrate. A cooling member joined through a material, and the cooling member is a composite member in which a thermal stress absorbing member made of aluminum and a heat conductive metal member are stacked, and the thermal stress absorbing member is the insulating member It is arrange | positioned at the side joined with a board | substrate back surface, The yield stress of the said thermal-stress absorption member is smaller than the yield stress of the said joining material, It is characterized by the above-mentioned.

  A semiconductor device according to another aspect of the present invention includes an insulating substrate including an insulating plate and a conductive plate provided on both surfaces of the insulating plate, a semiconductor chip provided on the insulating substrate, and a back surface of the insulating substrate. The cooling member is a composite member in which a thermal stress absorbing member made of aluminum and a heat conductive metal member are integrated, and the thermal stress absorbing member is formed on the back surface of the insulating substrate. It is arrange | positioned at the side to join and the said thermal stress absorption member is comprised with the aluminum of purity 99.5% or more, It is characterized by the above-mentioned.

  A method of manufacturing a semiconductor device according to an aspect of the present invention includes: (a) preparing an insulating substrate including an insulating plate and conductive plates provided on both surfaces of the insulating plate; and (b) a semiconductor on the insulating substrate. A step of disposing a chip, (c) a step of forming a cooling member which is a composite member by integrating a thermal stress absorbing member and a heat conducting metal member made of aluminum by hot rolling, and (d) And a step of bonding the thermal stress absorbing member side of the cooling member to the back surface of the insulating substrate via a bonding material, wherein the yield stress of the thermal stress absorbing member is smaller than the yield stress of the bonding material. Features.

  A method of manufacturing a semiconductor device according to another aspect of the present invention includes: (a) preparing an insulating substrate including an insulating plate and a conductive plate provided on both surfaces of the insulating plate; and (b) on the insulating substrate. A step of disposing a semiconductor chip; (c) a step of forming a cooling member which is a composite member from a heat stress absorbing member and a heat conductive metal member made of aluminum; and (d) the thermal stress of the cooling member. Forming a linear expansion coefficient adjusting layer made of copper or a copper alloy on the absorbing member side using a cold spray method; and (e) the linear expansion coefficient on the back surface of the insulating substrate via a bonding material. A step of bonding the adjustment layer, wherein the yield stress of the thermal stress absorbing member is smaller than the yield stress of the bonding material, and at least a portion of the conductive plate that contacts the bonding material is made of copper or a copper alloy. It is characterized by .

  According to the said aspect of this invention, the thermal stress resulting from a difference with a thermal expansion coefficient can be relieve | moderated by using a thermal stress absorption member. Therefore, heat transferability, workability, reliability, and cost can be satisfied.

  The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

It is sectional drawing which shows the structure of the semiconductor device regarding embodiment. It is a circuit diagram of a general IGBT module for a three-phase inverter. It is sectional drawing at the time of comprising the semiconductor device regarding embodiment with the module of 1 in 1. FIG. It is a top view at the time of comprising the semiconductor device concerning embodiment with a module of 1 in 1. FIG. It is the figure which showed the temperature cycle number dependence of the crack length of a joining material. It is the figure which showed the relationship between the curvature or the wave | undulation of the cooling member after a temperature cycle, and a heat conductive metal member thickness / thermal stress absorption member thickness. It is the figure which showed the relationship between the purity and yield strength of aluminum. It is sectional drawing which shows the structure of the semiconductor device regarding embodiment. It is sectional drawing which shows the other example of the structure of the semiconductor device regarding embodiment.

  Hereinafter, embodiments will be described with reference to the accompanying drawings.

<First Embodiment>
<Configuration>
Hereinafter, when a material name such as copper or aluminum is described without any special designation, it includes, for example, a copper alloy or an aluminum alloy containing other additives.

  FIG. 1 is a cross-sectional view showing the structure of the semiconductor device according to this embodiment. FIG. 2 is a circuit diagram of a general IGBT module for a three-phase inverter. FIG. 3 is a cross-sectional view of the semiconductor device according to the present embodiment configured with a 1 in 1 module, and FIG. FIG. 4 shows a top view of the module.

  As shown in FIGS. 3 and 4, a plurality of insulating substrates 13 (six here) mounted with a semiconductor chip 11 (here, an IGBT chip, but no diode is shown) are cooled via a bonding material 23. Joined to the member 12. This module is sealed with an epoxy resin 8. Each module is electrically connected by a lead frame 9 via a bonding material 24.

  The cooling member 12 is a composite member in which a thermal stress absorbing member 1 composed of pure aluminum having a purity of at least 99.5% or more, desirably 99.9% or more, and a heat conductive metal member 2 such as copper or aluminum are stacked. It is.

  FIG. 5 is a diagram showing the temperature cycle number dependency of the crack length of the joining member in the thermal cycle test (−40 ° C. to 175 ° C.), that is, the crack length of the joining material. However, the bonding material 23 is high-strength solder, and the insulating substrate 13 is DBC. When the cooling member 12 is a composite material of an aluminum alloy (alloy name A6063) having a thickness of 6 mm and an aluminum having a thickness of 0.5 mm and a purity of 4N (in the figure, “thermal stress absorbing member 0.5t In the bonding material 23 is not substantially cracked. When the cooling member 12 is made of only an aluminum alloy (A6063) having a thickness of 6.5 mm (described as “no thermal stress absorbing member” in the figure), a crack develops in the bonding material 23.

  The thickness 101 of the thermal stress absorbing member 1 shown in FIG. 1 differs in its optimum value depending on the purity of aluminum because the relationship of cost to the effect differs depending on the purity of aluminum. The higher the aluminum purity is, the thinner the thickness is, but it may be set to about 0.05 to 0.5 mm.

  From the viewpoint of cost, weight, mechanical strength, and corrosion resistance, an aluminum alloy having a purity of less than 99.0%, for example, an aluminum alloy such as alloy designation A6063 (JIS symbol) is used for the heat conductive metal member 2. preferable.

  The heat conductive metal member 2 also serves as a structural material. In particular, in in-vehicle applications and the like, it is necessary to set the resonance frequency to be high so as not to resonate during actual use. Therefore, the heat conducting metal member 2 needs to have a certain thickness. For in-vehicle applications and the like, the thickness 102 of the heat conductive metal member 2 is preferably about 2 mm or more, and preferably 1 mm or more even in the case of fixed use. On the other hand, if the thickness is too thick, the increase in thermal resistance becomes remarkable, so it is desirable to set the thickness to 10 mm or less, preferably 4 mm or less.

  When the thermal stress absorbing member 1 is made of high-purity aluminum, deformation such as wrinkles may be seen in a temperature cycle or the like, and the deformation has a great influence on the heat conductive metal member 2 that also serves as a structural material. It is also important not to give

  FIG. 6 is a diagram showing the maximum swell or warp of the cooling member 12 after 1000 thermal cycle tests (−40 ° C. to 175 ° C.) have been completed. However, the bonding material 23 is high-strength solder, and the insulating substrate 13 is DBC. It can be seen that when the thermal conductive metal member 2 (here, aluminum alloy) is 8 times or more than the thermal stress absorbing member 1 (here, pure aluminum having a purity of 4N), there is almost no warpage or undulation. Further, it can be seen that when the heat conductive metal member 2 (here, an aluminum alloy) is thinner than the thermal stress absorbing member 1 (here, pure aluminum having a purity of 4N), deformation such as undulation or warpage is likely to occur. In particular, when the thermal stress absorbing member 1 is thicker (when the thickness 102 of the heat conducting metal member 2 is less than 1 times the thickness 101 of the thermal stress absorbing member 1), the mechanical characteristics of the cooling member 12 are Since it is governed by the thermal stress absorbing member 1, the swell or warpage is not a controlled value. Therefore, in the ratio of the thickness 101 of the thermal stress absorbing member 1 and the thickness 102 of the heat conducting metal member 2, it is preferable that the heat conducting metal member 2 is thick at least 1 time or more, desirably 8 times or more.

  The integration of the thermal stress absorbing member 1 and the heat conductive metal member 2 that is performed in advance is preferably performed by hot rolling from the viewpoint of stability of bonding strength and cost. Alternatively, a thermal stress absorbing member is formed as an aluminum film on the heat conducting metal member 2 by a cold spray method (a method in which a powder material is collided with a base material in a solid state at a melting temperature or lower to form a film) or a thermal spraying method. It is also possible to form 1.

  The thermal stress absorbing member 1 made of aluminum is the weakest layer, and gradually cracks due to fatigue failure due to a temperature cycle. When the joining interface between the heat conductive metal member 2 which is also a structural material and the thermal stress absorbing member 1 is formed of a brazing material or the like, it is not in the base material of the thermal stress absorbing member 1 but at the interface part at once, such as interface peeling. Cracks may develop. Therefore, it is desirable that the heat conductive metal member 2 and the thermal stress absorbing member 1 be joined directly without a joining material.

  The surface of the thermal stress absorbing member 1 in the cooling member 12 thus formed may be subjected to a surface treatment, for example, by Ni plating. Further, in order to increase the heat transfer coefficient of the cooling member 12, it is preferable that the heat conducting metal member 2 has a surface area enlarged by forming fins or grooves.

  Furthermore, a water jacket 21 for liquid cooling type cooling can be provided below the heat conducting metal member 2. The water jacket 21 is made of, for example, an aluminum alloy and is connected to the heat conducting metal member 2.

  On the other hand, the semiconductor chip 11 is bonded onto the insulating substrate 13 via a die bond material 22. For the die bond material 22, for example, a low-temperature sintered material of silver nanoparticles, a liquid phase diffusion bonding material such as Cu—Sn or Ag—Sn, or a bonding material that is a good electrical and thermal conductor such as solder is used. Can do. Furthermore, the semiconductor chip 11 and the insulating substrate 13 may be bonded by direct bonding such as Cu solid phase diffusion bonding or ultrasonic bonding.

  The insulating substrate 13 includes a conductive plate 5 that is in contact with the die bonding material 22, a conductive plate 7 that faces the cooling member 12, and an insulating ceramic 6 that is disposed between the conductive plate 5 and the conductive plate 7. These are integrated in advance using a brazing material or the like.

  For the conductive plate 5 and the conductive plate 7, a good electrical and thermal conductor such as copper or aluminum can be used. As the insulating ceramic 6, a ceramic that is an electrically insulating material and is a good conductor of heat, such as silicon nitride, aluminum nitride, or alumina, can be used.

  Furthermore, the conductive plate 7 of the insulating substrate 13 and the thermal stress absorbing member 1 of the cooling member 12 are joined via a joining material 23. As the bonding material 23, for example, a low-temperature sintered material of silver nanoparticles, a silver paste material, a liquid phase diffusion bonding material such as Cu-Sn or Ag-Sn, or a bonding material that is a good heat conductor such as solder is used. be able to. However, the yield stress (or proof stress) of the bonding material 23 needs to be larger than that of the thermal stress absorbing member 1 in the temperature range to be used. When joining with solder, the yield stress of the solder material is also a point to be noted, and for example, high-strength solder such as Sn—Cu—Sb is preferable.

  The conductive plate 7 and the thermal stress absorbing member 1 may be joined by direct joining such as Cu solid phase diffusion joining or ultrasonic joining without using the joining material 23.

  According to such a configuration, the thermal resistance from the semiconductor chip 11 which is a thermal heating element to the cooling member 12 is extremely small, and an excellent heat transfer property can be obtained. Further, most of the thermal stress caused by the difference in thermal expansion coefficient between the insulating substrate 13 and the cooling member 12 is absorbed by plastic deformation of the thermal stress absorbing member 1 (pure aluminum plate), and therefore the insulating substrate 13 and the cooling member 12 are cooled. The connection reliability with the member 12 is sufficiently ensured.

  FIG. 7 is a diagram showing the relationship between the purity and the yield strength of aluminum. In the figure, the vertical axis represents the yield strength (arb. Unit) of aluminum, and the horizontal axis represents the purity of aluminum.

  Even if it is aluminum with a purity of 99% or more generally called pure aluminum, the proof stress (yield stress) is different. If the purity is 3N (99.9%) or higher, work hardening hardly occurs. Therefore, if it sees only from this viewpoint, purity 3N (99.9%) or more is desirable.

  However, even if the purity is about 99.5%, the proof stress (yield stress) has a small difference from the purity of 4N (a little less than 2 times). Therefore, among the solders that are relatively inexpensive bonding materials, if the high-strength solder such as Sn-Cu-Sb described above, the proof stress (yield stress) of aluminum having a purity of 99.5% is the proof strength of the solder material ( There is a temperature range that is less than or equal to the yield stress, and there is no practical problem depending on the usage environment.

  Since the cost of the aluminum material is higher when the purity is higher, a suitable purity may be selected in the design in a range that does not cause a practical problem according to the use environment.

  As described above, since the thermal stress caused by the difference in thermal expansion coefficient between the insulating substrate 13 and the cooling member 12 can be relaxed with a simple structure, the thermal conductivity, workability, reliability, and cost are satisfied. Can be made.

  In this embodiment, a water-cooled type in which a water jacket 21 made of an aluminum alloy and a cooling member 12 are sealed by electron beam welding or FSW (friction stir welding) or the like at the outer peripheral portion of the cooling member 12. Although a cooler is disclosed, the cooler may be an air-cooled type. Even in the liquid cooling type, the seal between the water jacket 21 and the cooling member 12 is not limited to welding, and it is also possible to seal with a highly elastic material such as an O-ring or a gasket interposed therebetween.

  The material of the water jacket 21 is not limited to an aluminum alloy, but for example, an aluminum alloy such as the ADC 12 is suitable. If it is ADC12, it can manufacture using the aluminum die-casting method which is an inexpensive manufacturing method. Further, as described above, welding with the cooling member 12 is possible. Furthermore, since the linear expansion coefficient of the ADC 12 is the same as the linear expansion coefficient of the cooling member 12, no thermal stress is generated at the joint between the water jacket 21 and the cooling member 12. The ADC 12 is lightweight and inexpensive.

  In this embodiment, the number of semiconductor chips 11 mounted on the insulating substrate is one (see FIG. 1). However, semiconductor chips of the same type or different functions such as a combination of an IGBT and a diode may be used. It may be a case where a plurality of devices are mounted on the same insulating substrate. Various combinations are possible, such as when a plurality of insulating substrates are mounted on the same cooler (see FIG. 4).

  Further, regarding the material of the semiconductor chip 11, not only Si but also a so-called wide bandgap semiconductor such as SiC or GaN, or mixed mounting of them can be used, and there is no particular limitation. Here, the wide band gap semiconductor generally refers to a semiconductor having a forbidden band width of about 2 eV or more, and is represented by a group 3 nitride represented by GaN, a group 2 nitride represented by ZnO, and ZnSe. Group 2 chalcogenides and SiC are known.

  In particular, a SiC chip that can be used at a higher current density than the Si chip and that can reduce the chip area and the overall size of the device has a small chip area. Influence. Therefore, the present invention having good heat spread without disturbing the heat spread is suitable for a semiconductor device mounted with a SiC chip.

<Effect>
According to the present embodiment, the semiconductor device includes the insulating substrate 13, the semiconductor chip 11 provided on the insulating substrate 13, and the cooling member 12 bonded to the back surface of the insulating substrate 13 via the bonding material 23. .

  The insulating substrate 13 includes an insulating ceramic 6 as an insulating plate, and a conductive plate 5 and a conductive plate 7 provided on both surfaces of the insulating ceramic 6.

  The cooling member 12 is a composite member in which the thermal stress absorbing member 1 made of aluminum and the heat conducting metal member 2 are integrated.

  The thermal stress absorbing member 1 is disposed on the side to be bonded to the back surface of the insulating substrate 13, and the yield stress of the thermal stress absorbing member 1 is smaller than the yield stress of the bonding material 23.

  According to such a configuration, the thermal stress caused by the difference between the effective linear expansion coefficient of the insulating substrate 13 and the thermal expansion coefficient of the cooling member 12 is reduced by using the thermal stress absorbing member 1 having a simple structure. can do. Therefore, heat transferability, workability, reliability, and cost can be satisfied.

  In addition, according to the present embodiment, a plurality of insulating substrates 13 on which the semiconductor chip 11 is mounted are bonded to the thermal stress absorbing member 1 that is a part of the cooling member 12 via the bonding material 23, so that each insulating substrate Therefore, it is possible to provide a semiconductor device at a lower cost than when the thermal stress absorbing member 1 is provided.

  In addition, as a unique effect when this module is sealed with epoxy resin 8, it is easy to handle, and the characteristics of the semiconductor chip can be inspected before joining to the cooling plate, and only good products can be mounted on the cooling plate. In addition, the inverter may be configured with high quality and low cost.

  Even in the case of sealing with a gel-like material called a so-called case mold, effects other than the effects unique to the epoxy sealing can be obtained.

  Further, according to the present embodiment, the thermal stress absorbing member 1 is made of aluminum having a purity of 99.5% or more.

  According to such a configuration, the thermal stress generated by the difference between the effective linear expansion coefficient of the insulating substrate 13 and the linear expansion coefficient of the cooling member 12 is caused by plastic deformation of the (pure aluminum material) of the thermal stress absorbing member 1. Can be reduced. By adopting aluminum having a purity of 99.5% or more, even when the bonding material 23 is made of solder (high strength solder), the yield stress (or proof stress) of the bonding material 23 is determined from the yield stress of the thermal stress absorbing member 1. It is possible to set a large value, and it is possible to ensure sufficient reliability with respect to the temperature cycle while employing relatively inexpensive solder for the bonding material 23.

  Moreover, according to this embodiment, the heat conductive metal member 2 is comprised with the aluminum alloy of purity less than 99.0%.

  According to such a configuration, joining of the thermal stress absorbing member 1 made of pure aluminum and the heat conductive metal member 2 is easy, which is desirable from the viewpoint of cost, weight, mechanical strength, and corrosion resistance. Furthermore, it is common to use an aluminum alloy (aluminum die-cast) from the viewpoint of light weight, high corrosion resistance, and cost for the water jacket 21, but according to this structure, welding is possible and a seal structure is unnecessary. Therefore, it can be manufactured at low cost. Moreover, the mismatch of a mechanical characteristic can be suppressed by using the same raw material.

  According to the present embodiment, the semiconductor device includes the water jacket 21 as a jacket member made of an aluminum alloy connected to the heat conducting metal member 2 in the cooling member 12.

  According to such a configuration, since the water jacket 21 is made of an aluminum alloy (aluminum die cast), the cooling member 12 can be fixed and sealed by welding, and a special seal structure is not required. Therefore, it can be manufactured at low cost. Moreover, the mismatch of a mechanical characteristic can be suppressed by using the same raw material.

  Further, according to the present embodiment, the method for manufacturing a semiconductor device includes a step of preparing the insulating substrate 13, a step of disposing the semiconductor chip 11 on the insulating substrate 13, a step of forming the cooling member 12, and the insulating substrate. And a step of bonding the thermal stress absorbing member 1 side of the cooling member 12 to the back surface via the bonding material 23.

  The step of preparing the insulating substrate 13 is a step of preparing the insulating substrate 13 including the insulating ceramic 6 as an insulating plate and the conductive plate 5 and the conductive plate 7 provided on both surfaces of the insulating ceramic 6.

  The step of forming the cooling member 12 is a step of forming the cooling member 12 which is a composite member by integrating the thermal stress absorbing member 1 and the heat conducting metal member 2 made of aluminum by hot rolling. is there.

  Note that the yield stress of the thermal stress absorbing member 1 is smaller than the yield stress of the bonding material 23.

  According to such a configuration, the thermal stress caused by the difference between the effective linear expansion coefficient of the insulating substrate 13 and the thermal expansion coefficient of the cooling member 12 is reduced by using the thermal stress absorbing member 1 having a simple structure. can do. Therefore, heat transferability, workability, reliability, and cost can be satisfied.

Second Embodiment
<Configuration>
FIG. 8 is a cross-sectional view showing the structure of the semiconductor device according to this embodiment. In the case of a so-called DBC substrate (direct bonded copper substrate, copper-clad substrate) in which the conductive plate 5a and the conductive plate 7a of the insulating substrate 13a are formed of copper or a copper alloy, as shown in FIG. It is also possible to provide a linear expansion coefficient adjusting layer 31 that is joined to and integrated with 12 thermal stress absorbing members 1 (pure aluminum plate).

  The linear expansion coefficient adjusting layer 31 is preferably formed from the same copper or copper alloy as the conductive plates (conductive plate 5a and conductive plate 7a) of the DBC substrate. Moreover, as the formation method, the method of joining by integrating the thermal stress absorption member 1 side of the cooling member 12 and the copper plate (linear expansion coefficient adjusting layer 31) by brazing or the like may be used. A method of forming the linear expansion coefficient adjustment layer 31 as a copper film on the thermal stress absorbing member 1 side of the member 12 by a cold spray method or a thermal spraying method may be used. In particular, the cold spray method is preferable because it is relatively inexpensive and can form a thick copper film over a large area.

  Then, the linear expansion coefficient adjustment layer 31 is bonded to the back surface of the insulating substrate 13a through the bonding material 23.

  According to such a configuration, since both the upper and lower surfaces of the bonding material 23 are members made of the same material, the thermal stress applied to the bonding material 23 is equalized, and the bonding reliability between the insulating substrate 13a and the cooling member 12 is ensured. The property is further improved. In particular, when the bonding material 23 is solder, the effect is remarkable.

<Modification>
FIG. 9 is a cross-sectional view showing another example of the structure of the semiconductor device according to this embodiment. As shown in FIG. 9, the conductive plate 5 b of the insulating substrate 13 b is composed of a copper plate 51 and an aluminum plate 52. The conductive plate 7 b of the insulating substrate 13 b is composed of an aluminum plate 72 and a copper plate 71. The copper plate 51 and the copper plate 71 are made of copper or a copper alloy. Aluminum plate 52 and aluminum plate 72 are made of aluminum or an aluminum alloy.

  When the surface side of the conductive plate 7b is copper (copper plate 71) as in the case of the insulating substrate 13b in which the conductive plate 5b, the insulating ceramic 6 and the conductive plate 7b are all integrated, as in the above case, the thermal stress is absorbed. By providing the linear expansion coefficient adjusting layer 31 integrally formed on the member 1, the same effect as described above can be obtained.

  Furthermore, when the aluminum plate 72 (and also the aluminum plate 52) is pure aluminum having a purity of at least 99.5% or more, preferably 99.9% or more, the thermal stress of the insulating ceramic main cause of the insulating substrate 13b is relieved. Therefore, the bonding reliability between the insulating substrate 13b and the cooling member 12 is further improved.

<Effect>
According to this embodiment, the copper plate 71 which is a part which contacts the joining material 23 of the conducting plate 7a or the conducting plate 7b is made of copper or a copper alloy. The semiconductor device includes a linear expansion coefficient adjustment layer 31 made of copper or a copper alloy bonded to the back surface of the insulating substrate via the bonding material 23. The cooling member 12 is further joined to the linear expansion coefficient adjustment layer 31.

  According to such a configuration, in the case of a so-called DBC substrate using copper having high thermal conductivity for the conductive plate of the insulating substrate, the same copper as the conductive plate (conductive plate 7a or copper plate 71) of the portion in contact with the bonding material 23. Alternatively, the linear expansion coefficient adjusting layer 31 made of a copper alloy is bonded to the back surface of the insulating substrate via the bonding material 23, so that the thermal stress is equalized on the members on both sides of the bonding material 23, and the insulating substrate and the cooling layer are cooled. The joint reliability with the member 12 is improved. In particular, when the bonding material 23 is made of solder, the effect is remarkable.

  Moreover, according to this embodiment, the conducting plate 5b and the conducting plate 7b are configured by a laminated structure of copper or copper alloy and aluminum or aluminum alloy.

  According to such a configuration, when a laminated structure in which copper having high thermal conductivity and aluminum that is easily plastically deformed is used as the conducting plate, a portion of the conducting plate (copper plate 71) that contacts the bonding material 23 is used. The thermal expansion is equalized on the members on both sides of the bonding material 23 by bonding the linear expansion coefficient adjustment layer 31 made of the same copper or copper alloy to the back surface of the insulating substrate 13b via the bonding material 23. Further, the bonding reliability between the insulating substrate 13b and the cooling member 12 is improved. In particular, when the bonding material 23 is made of solder, the effect is remarkable.

  Moreover, according to this embodiment, the conducting plate 5b and the conducting plate 7b include a layer made of aluminum having a purity of 99.5% or more.

  According to such a configuration, the thermal stress due to the insulating ceramic 6 of the insulating substrate 13b is relieved, so that the bonding reliability between the insulating substrate 13b and the cooling member 12 is improved.

  Further, according to the present embodiment, the method for manufacturing a semiconductor device includes a step of preparing an insulating substrate, a step of disposing the semiconductor chip 11 on the insulating substrate, a step of forming the cooling member 12, and a linear expansion coefficient adjustment. The step of forming the layer 31 and the step of bonding the linear expansion coefficient adjusting layer 31 to the back surface of the insulating substrate via the bonding material 23 are provided.

  The step of preparing an insulating substrate is a step of preparing an insulating substrate provided with insulating ceramics 6 as insulating plates and conductive plates provided on both surfaces of the insulating ceramics 6.

  The step of forming the cooling member 12 is a step of forming the cooling member 12 that is a composite member from the thermal stress absorbing member 1 and the heat conducting metal member 2 made of aluminum.

  The step of forming the linear expansion coefficient adjustment layer 31 is a step of forming the linear expansion coefficient adjustment layer 31 made of copper or a copper alloy on the thermal stress absorbing member 1 side of the cooling member 12 using a cold spray method. It is.

  Note that the yield stress of the thermal stress absorbing member 1 is smaller than the yield stress of the bonding material 23, and at least the portion of the conductive plate 7a or the conductive plate 7b that contacts the bonding material 23 is made of copper or a copper alloy.

  According to such a configuration, in the case of a so-called DBC substrate using copper having high thermal conductivity for the conductive plate of the insulating substrate, the same copper as the conductive plate (conductive plate 7a or copper plate 71) of the portion in contact with the bonding material 23. Alternatively, the linear expansion coefficient adjusting layer 31 made of a copper alloy is bonded to the back surface of the insulating substrate via the bonding material 23, so that the thermal stress is equalized on the members on both sides of the bonding material 23, and the insulating substrate and the cooling layer are cooled. The joint reliability with the member 12 is improved. In particular, the cold spray method for forming the linear expansion coefficient adjustment layer 31 is a method of forming the linear expansion coefficient adjustment layer 31 as a copper film, and is preferable because a thick copper film can be formed over a large area at a relatively low cost.

  In each of the above embodiments, the material, material, size, shape, relative arrangement relationship, or implementation condition of each component may be described, but these are examples in all aspects, and The invention is not limited to that described. Thus, countless variations not illustrated are envisaged within the scope of the present invention. For example, a case where an arbitrary component is modified or omitted, and a case where at least one component in at least one embodiment is extracted and combined with a component in another embodiment are included.

  DESCRIPTION OF SYMBOLS 1 Thermal stress absorption member, 2 Thermal conductive metal member, 5, 5a, 5b, 7, 7a, 7b Conductor plate, 6 Insulating ceramics, 8 Epoxy resin, 9 Lead frame, 11 Semiconductor chip, 12 Cooling member, 13, 13a, 13b Insulating substrate, 21 Water jacket, 22 Die bond material, 23, 24 Bonding material, 31 Linear expansion coefficient adjustment layer, 51, 71 Copper plate, 52, 72 Aluminum plate, 101, 102 Thickness.

A semiconductor device according to one embodiment of the present invention includes an insulating substrate including an insulating plate and a conductive plate provided on both surfaces of the insulating plate, a semiconductor chip provided on the insulating substrate, and a back surface of the insulating substrate. A cooling member comprising a cooling member joined via a material and a cooler jacket made of an aluminum alloy , wherein the cooling member is made of a thermal stress absorbing member made of aluminum and an aluminum alloy A heat conductive metal member is an integrated composite member, and a protrusion or a groove is formed on the surface of the heat conductive metal member opposite to the surface connected to the heat stress absorbing member, and the heat stress absorbing member Is arranged on the side to be bonded to the back surface of the insulating substrate, and the yield stress of the thermal stress absorbing member is smaller than the yield stress of the bonding material.

A semiconductor device according to another aspect of the present invention includes an insulating substrate including an insulating plate and a conductive plate provided on both surfaces of the insulating plate, a semiconductor chip provided on the insulating substrate, and a back surface of the insulating substrate. And a cooler comprising a cooler jacket made of an aluminum alloy , wherein the cooling member comprises a thermal stress absorbing member made of aluminum and a thermally conductive metal member made of aluminum alloy Are stacked , and a protrusion or a groove is formed on the surface of the heat conducting metal member opposite to the surface connected to the heat stress absorbing member, and the heat stress absorbing member is connected to the back surface of the insulating substrate. It is arrange | positioned at the side to join and the said thermal-stress absorption member is comprised with the aluminum of purity 99.5% or more, It is characterized by the above-mentioned.

A method of manufacturing a semiconductor device according to an aspect of the present invention includes: (a) preparing an insulating substrate including an insulating plate and conductive plates provided on both surfaces of the insulating plate; and (b) a semiconductor on the insulating substrate. The step of arranging the chip and (c) the heat stress absorbing member made of aluminum and the heat conducting metal member made of aluminum alloy are integrated by hot rolling to form a cooling member which is a composite member And (d) bonding the thermal stress absorbing member side of the cooling member to the back surface of the insulating substrate via a bonding material, wherein the yield stress of the thermal stress absorbing member is It is characterized by being smaller than the yield stress.

A method of manufacturing a semiconductor device according to another aspect of the present invention includes: (a) preparing an insulating substrate including an insulating plate and a conductive plate provided on both surfaces of the insulating plate; and (b) on the insulating substrate. A step of disposing a semiconductor chip; (c) a step of forming a cooling member which is a composite member from a thermal stress absorbing member made of aluminum and a heat conductive metal member made of aluminum alloy ; Forming a linear expansion coefficient adjusting layer made of copper or a copper alloy on the thermal stress absorbing member side of the cooling member using a cold spray method; and (e) a bonding material on the back surface of the insulating substrate. A step of bonding the linear expansion coefficient adjusting layer, wherein a yield stress of the thermal stress absorbing member is smaller than a yield stress of the bonding material, and at least a portion of the conductive plate that contacts the bonding material is copper. Or with copper alloy Made is characterized in that is.

Claims (14)

An insulating substrate comprising an insulating plate and conductive plates provided on both sides of the insulating plate;
A semiconductor chip provided on the insulating substrate;
A cooling member bonded to the rear surface of the insulating substrate via a bonding material;
The cooling member is a composite member in which a thermal stress absorbing member made of aluminum and a heat conductive metal member are integrated,
The thermal stress absorbing member is disposed on the side to be bonded to the back surface of the insulating substrate,
The yield stress of the thermal stress absorbing member is smaller than the yield stress of the bonding material,
Semiconductor device. A plurality of insulating substrates are arranged on the cooling member.
The semiconductor device according to claim 1. The thermal stress absorbing member is made of aluminum having a purity of 99.5% or more,
The semiconductor device according to claim 1. At least a portion of the conductive plate that comes into contact with the bonding material is made of copper or a copper alloy,
A member including a linear expansion coefficient adjustment layer made of copper or a copper alloy integrated with the cooling member is bonded to the back surface of the insulating substrate via the bonding material.
The semiconductor device according to claim 1. The conductive plate is composed of a laminated structure of copper or a copper alloy and aluminum or an aluminum alloy,
The semiconductor device according to claim 4. The conductive plate includes a layer composed of aluminum having a purity of 99.5% or more,
The semiconductor device according to claim 5. The heat conductive metal member is made of an aluminum alloy having a purity of less than 99.0%,
The semiconductor device according to claim 1. Further comprising a jacket member made of an aluminum alloy connected to the heat conducting metal member in the cooling member,
The semiconductor device according to claim 1. The semiconductor chip is made of SiC,
The semiconductor device according to claim 1. The cooling member is a composite member in which a heat stress absorbing member made of aluminum and a heat conducting metal member are integrated, and the thickness of the heat conducting metal member is not less than 1 mm and not more than 10 mm, and the thickness of the heat stress absorbing member is Is less than or equal to the thickness of the thermally conductive metal member,
The semiconductor device according to claim 1. An insulating substrate comprising an insulating plate and conductive plates provided on both sides of the insulating plate;
A semiconductor chip provided on the insulating substrate;
A cooling member bonded to the back surface of the insulating substrate,
The cooling member is a composite member in which a heat stress absorbing member made of aluminum and a heat conductive metal member are stacked,
The thermal stress absorbing member is disposed on the side to be bonded to the back surface of the insulating substrate,
The thermal stress absorbing member is made of aluminum having a purity of 99.5% or more,
Semiconductor device. The cooling member is a composite member in which a heat stress absorbing member made of aluminum and a heat conducting metal member are integrated, and the thickness of the heat conducting metal member is not less than 1 mm and not more than 10 mm, and the thickness of the heat stress absorbing member is Is less than or equal to the thickness of the thermally conductive metal member,
The semiconductor device according to claim 11. (A) preparing an insulating substrate comprising an insulating plate and a conductive plate provided on both surfaces of the insulating plate;
(B) disposing a semiconductor chip on the insulating substrate;
(C) a step of forming a cooling member which is a composite member by integrating the thermal stress absorbing member and the heat conductive metal member made of aluminum by hot rolling;
(D) a step of bonding the thermal stress absorbing member side of the cooling member to the back surface of the insulating substrate via a bonding material;
The yield stress of the thermal stress absorbing member is smaller than the yield stress of the bonding material,
A method for manufacturing a semiconductor device. (A) preparing an insulating substrate comprising an insulating plate and a conductive plate provided on both surfaces of the insulating plate;
(B) disposing a semiconductor chip on the insulating substrate;
(C) forming a cooling member which is a composite member from a thermal stress absorbing member made of aluminum and a heat conductive metal member;
(D) forming a linear expansion coefficient adjustment layer made of copper or a copper alloy on the thermal stress absorbing member side of the cooling member using a cold spray method;
(E) a step of bonding the linear expansion coefficient adjustment layer to the back surface of the insulating substrate via a bonding material;
The yield stress of the thermal stress absorbing member is smaller than the yield stress of the bonding material,
At least a portion of the conductive plate that contacts the bonding material is made of copper or a copper alloy,
A method for manufacturing a semiconductor device.

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