JP2016225552A - High heat-resistant solder bonded semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device having high heat resistance and high reliability.SOLUTION: In a high heat-resistant solder bonded semiconductor device, a semiconductor element and a substrate are bonded with a solder that expresses super plasticity. The high heat-resistant solder bonded semiconductor device is characterized in that the solder is protruded to the outside from an end of the semiconductor element while the solder is kept in a semi-molten state to prevent the solder from flowing out and the solder is to be swelled to an upper side than a lower face of the semiconductor element, and then, the solder is allowed to express super plasticity, and stress strain at the interface between the solder and the semiconductor element and stress strain at the interface between the solder and the substrate are suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device in which a substrate and a semiconductor element are joined with high heat-resistant solder.

  A power device is a semiconductor element for power control used in a hybrid vehicle, an inverter for solar power generation, and the like, and is an electronic component that is the center of power electronics. Examples of power devices include rectifier diodes, power MOSFETs (metal oxide film / field effect transistors), IGBTs (insulated gate bipolar transistors), thyristors, and the like, and solder is used to join the power device to the substrate. Pb (lead) and Sn (tin) alloys have been used as solder, but lead-free solder has also been developed because it is harmful to the human body and adversely affects the natural environment.

  Patent Document 1 discloses a semiconductor device using a Zn (zinc) -Al (aluminum) eutectoid alloy bonding material that is lead-free, has a high melting point, and can be bonded in a solid phase. Lead-free solder tends to create fine voids called voids, but in the invention described in Patent Document 1, it is possible to make void-free by joining the objects in a solid state using a superplastic phenomenon. it can.

JP 2009-1113050 A

  However, in the case of the invention described in Patent Document 1, when the substrate is warped by heat or the like, stress is applied to the end of the semiconductor element, and a crack is generated in the solder joint between the semiconductor element and the substrate. In extreme cases, the semiconductor element may be peeled off from the substrate. When cracks occur in the solder joints, electrical conduction and thermal conduction are deteriorated, so a highly reliable semiconductor device with high heat resistance is required.

  Accordingly, an object of the present invention is to provide a highly heat-resistant and highly reliable semiconductor device.

  In order to solve the above problems, a high heat-resistant solder-bonded semiconductor device according to the first aspect of the present invention is a high-heat-resistant solder-bonded semiconductor device in which a semiconductor element and a substrate are bonded with solder that expresses superplasticity. In a semi-molten state so as not to flow out, the solder protrudes outward from the end of the semiconductor element and rises above the lower surface of the semiconductor element, and then the solder exhibits superplasticity, It is characterized by suppressing stress strain at the interface between the solder and the semiconductor element and at the interface between the solder and the substrate.

  According to a first aspect of the present invention, the solder protrudes outward from the end of the semiconductor element at at least one of the ends of the bonded semiconductor elements, and from the lower surface of the semiconductor element. Is also raised upward.

  In the first invention, the solder is characterized in that it exhibits a superplasticity, that is, Al is 22 to 68% by mass and Zn is 78 to 32% by mass.

  In the first invention, the solder is characterized in that Al is 22 to 68% by mass, impurities are 2% by mass or less, and the balance is Zn.

  In the first invention, the solder is characterized in that Zn is 78 to 32 mass%, impurities are 2 mass% or less, and the balance is Al.

  The first invention is characterized in that the shortest distance between the solder and the pn junction of the semiconductor element is larger than the width of the depletion layer of the pn junction.

  Furthermore, a method for manufacturing a high heat-resistant solder-bonded semiconductor device according to a second aspect of the present invention includes a solder preparation step of preparing a solder composed of Al and Zn that exhibits superplasticity, and a semiconductor element as a substrate through the solder. A semiconductor element installation step, a heating step for heating the solder so that the solder does not flow out, and semi-melting, and pressurizing the solder so that the peripheral portion of the solder is Zn-rich and the center portion is Al-rich. Thus, the pressurizing step of protruding the peripheral edge outside the edge of the semiconductor element and raising the peripheral edge above the lower surface of the semiconductor element, cooling the solder, and exceeding the solder Decreasing temperature at which the semiconductor element and the substrate are solder-bonded while exhibiting plasticity and suppressing stress strain at the interface between the solder and the semiconductor element and the interface between the solder and the substrate It has a bonding step, and wherein the.

  According to the present invention, a highly heat-resistant and highly reliable semiconductor device can be provided.

It is sectional drawing of the semiconductor device which concerns on Example 1 of this invention. It is the image which image | photographed the cross section of the semiconductor device which concerns on Example 1 of this invention. It is a figure which shows the stress concerning the solder joint part of the semiconductor device which concerns on Example 1 of this invention, (a) is a solder joint part of this invention, (b) is a conventional solder joint part. It is a flowchart which shows the flow of the joining method of the semiconductor which concerns on Example 2 of this invention. It is a figure which shows each process of the joining method of the semiconductor which concerns on Example 2 of this invention, (a) is a heating process, (b) is a pressurization process. It is a figure which shows the process of temperature fall and joining of the semiconductor bonding method which concerns on Example 2 of this invention. It is a graph which shows the state of the solder in each process of the joining method of the semiconductor which concerns on Example 2 of this invention. It is a graph which shows the state of the solder in each process of the joining method of the semiconductor which concerns on Example 3 of this invention. It is a figure which shows the conditions of the solder for raising the withstand voltage of the semiconductor device which concerns on Example 4 of this invention. It is a figure which shows the high withstand voltage | pressure of the semiconductor device which concerns on Example 4 of this invention, (a) is a case where a semiconductor element is covered with insulating resin, (b) formed the oxide film on the surface of solder | pewter Is the case.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, what has the same function attaches | subjects the same code | symbol, and the repeated description may be abbreviate | omitted.

  First, the high heat-resistant solder junction semiconductor device according to the present invention will be described. FIG. 1 is a cross-sectional view of the semiconductor device 100, and FIG. 2 is an image obtained by photographing the cross section of the semiconductor device 100. 3A is a diagram showing the stress applied to the solder joint portion of the semiconductor device 100, and FIG. 3B is a diagram showing the stress applied to the solder joint portion of the conventional semiconductor device 110. FIG. 5 is a diagram for comparing the present invention with the prior art.

  As shown in FIG. 1, the semiconductor device 100 is obtained by bonding a semiconductor element 200 and a substrate 300 with a high heat-resistant solder 400. The semiconductor device 100 is manufactured through a pre-process and a post-process in the manufacturing process. Here, in the post-process, the semiconductor element 200 is mounted and the semiconductor element 200 and the substrate 300 are soldered. 400 is used for soldering.

  The semiconductor element 200 is an electronic component manufactured by providing an electrode on a semiconductor in the previous process, and is a state in which the wafer manufactured in the previous process is separated into chips. As a semiconductor material, SiC (silicon carbide, silicon carbide) or the like having higher performance is used instead of conventional Si (silicon, silicon). In addition to SiC, a high-performance compound semiconductor material such as GaN (gallium nitride) or diamond may be used.

  Various devices can be used for the semiconductor element 200. As an example of the semiconductor element 200, a BJT (bipolar transistor) is shown in FIG. In the BJT, an n-type semiconductor 201, a p-type semiconductor 202, and an n-type semiconductor 203 are alternately pn-junctioned, an emitter electrode 204 is formed on the n-type semiconductor 201, a base electrode 205 is formed on the p-type semiconductor 202, and a collector electrode 206 is formed on the n-type semiconductor 203. And has a current amplification and switching function.

  In the substrate 300, SiN (silicon nitride, silicon nitride) or the like is laminated as an insulating film 303 between the copper plate 302 and the copper plate 301 to be a wiring, and a coating 304 such as Ni (nickel) plating is formed on the surface of the copper plate 301. It has been applied. Since the allowable current is increased by increasing the thickness of the wiring, it is suitable for mounting a power device. Note that the substrate 300 may have another structure.

  The solder 400 uses Al—Zn solder that does not contain lead. Al—Zn solder is an alloy in which Al and Zn are blended at a predetermined ratio, and develops superplasticity when heated to a certain range of temperature. Superplasticity is a phenomenon in which, when a force is applied to a solid in a high temperature range, the plasticity grows more rapidly than usual. When the solder 400 is in a superplastic state, it becomes easy to enter minute uneven portions on the surface of the object to be joined, and stress applied to the solder 400 is relieved. When the solder 400 is further heated, it becomes a semi-molten state. That is, only the low melting point Zn is melted and the higher melting point Al is not melted. Further, when heated to the melting point of Al, it becomes liquid. The solder 400 may be made of other materials as long as the superplastic phenomenon appears in a predetermined temperature range.

  Before use, the solder 400 is a thin solder plate having a predetermined thickness, for example, about 100 μm, and has a planar shape substantially the same as that of the semiconductor element 200. The size may be slightly smaller or may be slightly larger. When the semiconductor element 200 is placed on the substrate 300 and bonded with the solder 400, the peripheral portion 402 of the solder 400 interposed between the semiconductor element 200 and the substrate 300 is connected to the semiconductor element 200 and the solder as shown in FIG. It will be in the state where it swelled from 400 contact surfaces.

  When the solder 400 is heated, the melted liquid does not flow out onto the substrate 300 but rises outside the semiconductor element 200 in a semi-molten state before becoming a liquid. In the case of an alloy, semi-molten is a state in which a metal (Al) having a high melting point remains solid and a metal (Zn) having a low melting point is dissolved and dispersed in a liquid state. In the case where the semiconductor element 200 is rectangular, the solder 400 is also a rectangular shape with a size that slightly protrudes from the four ends of the semiconductor element 200 to the outer peripheral side, but at least one of the four sides of the solder 400 needs to rise. is there. In addition, it is preferable that all the sides of the solder 400 are raised.

  As shown in FIG. 2, the center portion 401 of the solder 400 is sandwiched between the semiconductor element 200 and the substrate 300, and the peripheral portion 402 of the solder 400 protrudes from the end portion of the semiconductor element 200 and further rises upward. . A black dotted line indicates the boundary between the substrate 300 and the solder 400, and a white dotted line indicates the end of the semiconductor element 200.

  The merit of the solder 400 with the raised peripheral edge 402 will be described by comparing with the conventional solder 410. By causing the substrate 300 to be curved or applying vibration to the substrate 300, when stress 900 or 910 is applied to the end of the semiconductor element 200, the likelihood of cracks in the solder 400 or 410 is increased. Compare.

  As shown in FIG. 3A, in the present invention, when the semiconductor element 200 and the substrate 300 are joined and then attention is paid to the solder 400 protruding from each end of the semiconductor element 200, the surface of the solder 400 is the semiconductor element. It swells above the lower surface of 200. In other words, it may rise like a mountain above the surface where the solder 400 and the semiconductor element 200 are in contact, or obliquely above the surface where the solder 400 and the semiconductor element 200 are in contact. It may be raised in the direction.

  The stress 900 applied to the end where the semiconductor element 200 and the solder 400 are in contact with each other includes a vertical component 901 along the side surface of the semiconductor element 200 from the end and a tangential component along the raised surface of the solder 400 from the end. 902. As shown in FIG. 3A, the stress 900 is close to an angle close to vertical. That is, the stress 900 is close to the direction in which the solder 400 is vertically cut, and only penetrates to the vicinity of the peripheral portion 402 of the solder 400, and hardly penetrates to the back of the center portion 401 of the solder 400.

  As shown in FIG. 3B, in the related art, when the semiconductor element 200 and the substrate 300 are joined and then attention is paid to the solder 410 protruding from each end of the semiconductor element 200, the surface of the solder 410 is the semiconductor element 200. It does not rise above the lower surface of. That is, the surface of the solder 410 may be substantially horizontal, or may be melted and flowing. For the solder 400, the semiconductor element 200 side is the front surface and the substrate 300 side is the back surface.

  The stress 910 applied to the end where the semiconductor element 200 and the solder 410 are in contact with each other includes a vertical component 911 along the side surface of the semiconductor element 200 from the end and a tangent along the substantially horizontal surface of the solder 410 from the end. And derived from the component 912. As shown in FIG. 3B, the stress 910 is closer to the horizontal angle than the stress 900. That is, the stress 910 is close to the direction of cutting the solder 410 horizontally, and easily enters from the peripheral edge 402 of the solder 410 to the back of the central portion 401 of the solder 410.

  In the prior art shown in FIG. 3B, when stress 910 is applied to the end portion of the semiconductor element 200, the semiconductor device 200 enters deeply toward the center portion 401 of the solder 410. It becomes easy to cut the solder 410 in the horizontal direction. On the other hand, in the present invention shown in FIG. 3A, when stress 900 is applied to the end portion of the semiconductor element 200, the semiconductor device 100 operates only shallowly from the vicinity of the peripheral portion 402 of the solder 400. The solder 400 is less likely to be cut in the horizontal direction even by repeated thermal stress due to the above. That is, according to the present invention, it is possible to provide the semiconductor device 100 with high heat resistance and high reliability.

  In order to manufacture the SiC semiconductor device described above, a method for bonding semiconductor elements by solder will be described. FIG. 4 is a flowchart showing a flow of a semiconductor bonding method. 5A is a diagram showing a heating process, FIG. 5B is a diagram showing a pressurizing process, and FIG. 6 is a diagram showing a temperature lowering / joining process. FIG. 7 is a graph showing the state of solder in each step of the semiconductor bonding method.

  As shown in FIG. 4, the semiconductor element bonding method 500 includes steps of solder preparation 510, semiconductor element installation 520, heating 530, pressurization 540, temperature drop / bonding 550, and the like. Note that in the semiconductor element bonding method 500, a plurality of processes may be combined into one, or another process may be added. Moreover, if the order of two processes is interchangeable, they may be interchanged. Furthermore, if there is no problem even if some steps are omitted, they may be omitted.

  Also in this embodiment, various devices can be used as the semiconductor element 210. As an example, a power MOSFET having a DMOS (double diffusion metal oxide film) structure is shown in FIGS. In the power MOSFET, an n-type semiconductor 214 having a high n-type impurity concentration is used as a substrate, an n-type semiconductor 213 having a low n-type impurity concentration is formed thereon by epitaxial growth, and a low-concentration p-type semiconductor is further formed on the surface side. 212 and a high-concentration n-type semiconductor 211 are formed by ion implantation.

A source electrode 216 on the upper surface of the semiconductor element 210 is provided, and a gate oxide film 218 is formed with SiO ₂ (silicon dioxide) or the like, and then a gate electrode 215 is provided. A drain electrode 217 is provided on the lower surface of the n-type semiconductor 214. When a positive voltage is applied to the gate electrode 215 with a forward bias applied between the drain electrode 217 and the source electrode 216, a channel 219 (electron layer) is induced under the gate oxide film 218, and a current flows. .

  In the step of solder preparation 510, in order to increase the positional accuracy in installing the semiconductor device, the substrate 300, the semiconductor element 210 installed on the substrate 300, the solder 420 for bonding the semiconductor element 210 to the substrate 300, and other semiconductor elements. Prepare jigs as needed. As the substrate 300, a thick copper substrate suitable for a power device is used. As the semiconductor element 210, a material made of SiC having excellent heat resistance or the like is used. As the solder 420, one that exhibits superplasticity in a predetermined temperature range is used. For example, an alloy containing about 22 mass% Al and about 78 mass% Zn is used.

  As shown in FIG. 7, the melting point of Al is about 660 degrees, and the melting point of Zn is about 420 degrees. When the ratio of Al and Zn in the solder 420 changes, the melting point also changes as shown in the curve. In addition, since Al and Zn have different melting points, there is a region in which Al having a high melting point remains solid and Zn having a low melting point is in a semi-molten state in which it is first liquefied. From the semi-molten state, it passes through the alpha (Al) region where there are many Al crystals, and then becomes solid after the crystals grow.

  In the process of semiconductor element installation 520, the semiconductor element 210 is installed at a predetermined position with respect to the substrate 300. Note that a plate-like solder 420 is sandwiched between the substrate 300 and the semiconductor element 210. The solder 420 has a predetermined thickness and is as large as the semiconductor element 210. The upper surface of the solder 420 is simply in contact with the lower surface of the semiconductor element 210, and the lower surface of the solder 420 is simply in contact with the upper surface of the substrate 300.

  In the step of heating 530, as shown in FIG. 5A, the semiconductor device is heated to bring the solder 420 into a semi-molten state. As shown in FIG. 7, in the case of the solder 420 having about 22% Al and about 78% Zn, the semi-melting temperature is about 430 to 480 degrees. That is, when it is lower than about 430 degrees, it is solid, and when it is about 430 to 480 degrees, Al remains solid, but Zn is dispersed as a liquid, and when it exceeds about 480 degrees, it is completely dissolved. Become liquid. In this embodiment, it is assumed that the heating is performed up to about 450 degrees.

  In the step of pressing 540, as shown in FIG. 5B, by pressing the semiconductor device, the peripheral portion 422 of the solder 420 is pushed outward from the end portion of the semiconductor element 210, and the peripheral portion 422 is further transferred to the semiconductor. Raise above the lower surface of the element 210. In this embodiment, it is assumed that a pressure of about 10 to 20 MPa is applied.

  In the solder 420 in a semi-molten state, Zn that has been dissolved earlier is more likely to move to the peripheral portion 422 than to the central portion 421 due to pressure. As a result, the peripheral portion 422 of the solder 420 is in a Zn-rich state in which a large amount of Zn is contained, and the central portion 421 is in an Al-rich state in which the amount of Zn is reduced. As shown in FIG. 7, when the ratio of Al and Zn in the central portion 421 changes, and when Al becomes about 38% and Zn becomes about 62%, Zn begins to return to a solid state from the semi-molten state.

  In the temperature lowering / joining 550 process, as shown in FIG. 6, the Zn-rich peripheral portion 422 protrudes to the outside and rises, and when the central portion 421 becomes Al-rich, the semiconductor device is cooled to lower the temperature. To go. As shown in FIG. 7, when Al is about 38% and Zn is about 62% in the center portion 421, a superplastic phenomenon appears in the solder 420 when pressure is applied within a range of about 340 to 275 degrees. This phenomenon relieves stress strain at the interface between the solder 420 and the upper semiconductor element 200 and at the interface between the solder 420 and the lower substrate 300.

  When the semiconductor element 210 and the substrate 300 are soldered together, the stress strain of the solder joint is suppressed by using the solder 420 that expresses superplasticity by making Al and Zn into a predetermined ratio, and the electrical and thermal The conductivity of the can be improved. Further, by raising the peripheral edge portion 422 of the solder 420 in a semi-molten state, the stress is applied at an angle close to vertical, and the occurrence of cracks in the horizontal direction can be suppressed.

  The central portion 421 of the solder 420 has a higher Al composition than the peripheral portion 422, and the peripheral portion 422 of the solder 420 has a higher Zn composition than the central portion 421. In the solder joint portion directly under the semiconductor element 210, since the Al component is large, the thermal conductivity is good and high heat resistance can be achieved. That is, a large current can flow through the semiconductor element 210, and high output and high reliability can be achieved.

  Next, a case where solder 420 having different ratios of Al and Zn is used will be described. FIG. 8 is a graph showing the state of solder in each step of the semiconductor bonding method. As shown in FIG. 8, in this embodiment, in the step of preparing the solder 510, the solder 420 having about 38 mass% Al and about 62 mass% Zn is used. In the process of semiconductor element installation 520, the semiconductor element 210 is installed on the substrate 300 via the solder 420 therebetween.

  In the step of heating 530, the semiconductor device is heated to about 528 degrees to make the solder 420 in a semi-molten state. In the process of pressurization 540, the semiconductor device is placed under a pressure of about 10 to 20 MPa. The peripheral portion 422 of the solder 420 becomes Zn-rich and protrudes outward and rises, and the central portion 421 becomes Al-rich. The ratio of Al and Zn in the central portion 421 changes, and when the Al content is about 68% and the Zn content is about 32%, the solder 420 starts to return from a semi-molten state to a solid.

  When the peripheral portion 422 that has become rich in Zn protrudes to the outside, the tip of the peripheral portion 422 rises upward, but if the time of the semi-molten state is long in the process of pressurization 540, as shown in FIG. In some cases, it may be raised in a curved shape. Note that, when the semiconductor element 210 is viewed in a plan view, it protrudes to at least one of the surfaces, and when the semiconductor element 210 is viewed from the front or side, the solder 420 rises at least above the lower surface of the semiconductor element 210.

  In the temperature lowering / joining 550 process, when the temperature is lowered to about 275 degrees, a superplastic phenomenon appears in the solder 420 due to the pressure applied to the semiconductor device. When the solder 420 made of Al and Zn is used, it is necessary to develop a superplastic phenomenon. Therefore, as shown in FIGS. 7 and 8, Al is 22 to 68 mass% and Zn is 78 to 32 mass%. To the ratio.

  In consideration of the case where impurities such as Cu (copper) and Mg (magnesium) are mixed or the case where impurities are added to improve the performance of the semiconductor element 210, Al is 22 to 68 mass%, impurities are included. It is preferable that the ratio is 2% by mass or less, the balance is Zn, Zn is 78 to 32% by mass, impurities are 2% by mass or less, and the remainder is Al. In the process of changing from a region with a lot of Al crystals to a complete solid, the solder 420 becomes longer than usual even in a solid state. Thereby, the semiconductor element 210 and the board | substrate 300 can be soldered, suppressing the stress distortion of a soldering part.

  The breakdown voltage of the semiconductor device manufactured with the peripheral edge of the solder raised by the above semiconductor element bonding method will be described. FIG. 9 is a diagram illustrating soldering conditions for increasing the breakdown voltage of the semiconductor device. FIG. 10A shows the case where the semiconductor element is covered with an insulating resin to increase the breakdown voltage, and FIG. 10B shows the case where the oxide film is formed on the surface of the solder to increase the breakdown voltage.

  The semiconductor device 101 of this embodiment is manufactured by solder bonding the semiconductor element 220 and the substrate 300 using a solder 430 that exhibits superplasticity, based on the semiconductor element bonding method 500. Also in this embodiment, various devices can be used for the semiconductor element 220.

  As an example, FIGS. 9 and 10 show an IGBT in which BJT and MOSFET are combined. In the IGBT, first, a p-type semiconductor 224 having a high p-type impurity concentration is used as a substrate, an n-type semiconductor 223 having a low n-type impurity concentration is formed thereon by epitaxial growth, and a low-concentration p-type semiconductor 222 is further formed on the surface side. And a high concentration n-type semiconductor 221 is formed by ion implantation. An emitter electrode 226 is provided on the upper surface of the semiconductor element 220, a gate oxide film 228 is further formed, and then a gate electrode 225 is provided. A collector electrode 227 is provided on the lower surface of the p-type semiconductor 224.

  In the on state, the n-type semiconductor 221 is connected to the n-type semiconductor 223 through the channel, and electrons are supplied from the n-type semiconductor 221 and holes are supplied from the p-type semiconductor 224 to the n-type semiconductor 223. In the off state, electrons pass to the collector electrode 227 side, holes pass to the emitter electrode 226 side, and the depletion layer 230 extends from the pn junction on the emitter electrode 226 side toward the pn junction on the collector electrode 227 side.

  Since the solder 430 is raised above the lower surface of the semiconductor element 220, if the solder 430 is close to the end of the semiconductor element 220, there is a possibility that the insulation is broken due to a short circuit with the depletion layer 230. Therefore, the dielectric breakdown is prevented by keeping the distance between the pn junction of the semiconductor 220 and the solder 430 at a certain distance or more. Specifically, in all the pn junctions of the semiconductor 220, the shortest distance between the tip of the solder 430 and the closest position is made larger than the width of the depletion layer 230 in each pn junction.

Further, an effective method for maintaining the withstand voltage between the solder 430 and the semiconductor 220 will be described. As shown in FIG. 10A, the semiconductor device 102 is formed by coating the entire semiconductor element 220 by potting (resin-filling) with an insulating resin 431. As the insulating resin 431, a high heat-resistant silicon resin or the like can be used. Further, as shown in FIG. 10B, the semiconductor device 103 forms an oxide film 432 such as SiO _{2 on} the surface of the solder 430. Insulating means other than the two application examples may be provided.

  In this way, by securing an insulating space of a certain distance between the raised portion of the solder 430 and the semiconductor element 220, or by interposing an insulator such as the insulating resin 431 and the oxide film 432, the solder. The withstand voltage between 430 and the semiconductor element 220 can be made higher than the withstand voltage of the semiconductor element 220, and the high withstand voltage can be maintained as the semiconductor devices 101, 102, and 103.

  As mentioned above, although the Example of this invention was described, it is not limited to these. For example, SiC is used as the material for the semiconductor element, but other semiconductor materials may be used. Moreover, although Al-Zn solder was used as lead-free solder, the ratio of Al and Zn may be changed or an alloy other than Al and Zn may be used as long as it exhibits a superplastic phenomenon. .

  The present invention provides a power device manufactured using lead-free and void-free solder, such as a hybrid vehicle, an electric vehicle, a robot, a circuit for controlling a large current such as an inverter for photovoltaic power generation, and an electrical device. It can be used for a heavy load device.

DESCRIPTION OF SYMBOLS 100: Semiconductor device 101: Semiconductor device 102: Semiconductor device 103: Semiconductor device 110: Semiconductor device 200: Semiconductor element 201: N-type semiconductor 202: P-type semiconductor 203: N-type semiconductor 204: Emitter electrode 205: Base electrode 206: Collector Electrode 210: Semiconductor element 211: n-type semiconductor 212: p-type semiconductor 213: n-type semiconductor 214: n-type semiconductor 215: gate electrode 216: source electrode 217: drain electrode 218: gate oxide film 219: channel 220: semiconductor element 221 : N-type semiconductor 222: p-type semiconductor 223: n-type semiconductor 224: p-type semiconductor 225: gate electrode 226: emitter electrode 227: connector electrode 228: gate oxide film 230: depletion layer 300: substrate 301: copper plate 302: copper plate 303 : Insulating film 304: Film 400: Solder 401: Center part 402: Peripheral part 410: Solder 420: Solder 421: Center part 422: Peripheral part 423: Joining part 430: Solder 431: Insulating resin 432: Oxide film 500: Joining method of semiconductor element 510: Solder preparation 520: Semiconductor device installation 530: Heating 540: Pressurization 550: Temperature drop / joining 900: Stress 901: Vertical component 902: Tangent component 910: Stress 911: Vertical component 912: Tangent component

Claims (7)

A high heat-resistant solder-bonded semiconductor device in which a semiconductor element and a substrate are bonded with solder that expresses superplasticity,
After being in a semi-molten state so that the solder does not flow out, the solder protrudes outward from the end of the semiconductor element, and rises above the lower surface of the semiconductor element,
Superplasticity is expressed in the solder, and the stress strain at the interface between the solder and the semiconductor element and the interface between the solder and the substrate is suppressed.
A highly heat-resistant solder-bonded semiconductor device. At least one of the bonded end portions of the semiconductor element,
The solder protrudes outward from the end of the semiconductor element, and rises above the lower surface of the semiconductor element;
The high heat-resistant solder junction semiconductor device according to claim 1. The solder is a composition that expresses superplasticity, that is, Al is 22 to 68 mass%, Zn is 78 to 32 mass%,
The high heat-resistant solder junction semiconductor device according to claim 1 or 2. The solder is 22 to 68% by mass of Al, 2% by mass or less of impurities, and the balance is Zn.
The high heat-resistant solder junction semiconductor device according to claim 3. In the solder, Zn is 78 to 32% by mass, impurities are 2% by mass or less, and the balance is Al.
The high heat-resistant solder junction semiconductor device according to claim 3. The shortest distance between the solder and the pn junction of the semiconductor element is larger than the width of the depletion layer of the pn junction;
The high heat-resistant solder junction semiconductor device according to claim 1, wherein: A solder preparation step of preparing a solder composed of Al and Zn that exhibits superplasticity;
A semiconductor element installation step of installing the semiconductor element on the substrate via the solder;
A heating step of heating the solder and semi-melting the solder from flowing out;
By pressurizing the solder, the peripheral portion of the solder is Zn-rich and the central portion is Al-rich so that the peripheral portion protrudes beyond the end of the semiconductor element and above the lower surface of the semiconductor element Pressurizing step for raising the peripheral edge to
The solder is cooled, the super-plasticity is developed in the solder, and the semiconductor element and the substrate are soldered while suppressing the stress strain at the interface between the solder and the semiconductor element and the interface between the solder and the substrate. A temperature lowering / joining process for joining
A method for manufacturing a high heat-resistant solder-bonded semiconductor device.

Images