JP2014147966A - Joining material, joining method, joining structure, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining structure with high reliability which reduces the creep of a joining layers in joining of semiconductor elements.SOLUTION: As a jointing material between two kinds of members 1 and 3, a solder material which consists of at least one or more kinds of metal among Sb, Sn, Bi, and Zn is used in addition to Ag and In, and by joining in a half-molten state at a temperature equal to or higher than the solidus temperature and equal to or lower than the liquidus temperature of the solder material concerned, low melting point components 22 are discharged out of the joining layer. Based on the present process, by making the rate of a high-melting-point phase 21 of the joining layer increase, the creep resistance of a joining layer 2 is improved. The semiconductor element is a power semiconductor or a semiconductor strain sensor element.

Description

  The present invention relates to a bonding material, and also relates to a bonding method, a bonding structure, and a semiconductor device using the bonding material.

  In recent years, sensors that measure various physical quantities are attracting attention in order to improve product safety and optimize performance by grasping the status of devices and parts such as social infrastructure, industrial equipment, and automobiles. . There are various types of sensors, such as force, light, and acceleration, and their uses are also various. For example, by attaching a large number of strain sensors to a large structure such as a bridge and monitoring the state of strain, the life of the member can be grasped and maintainability can be improved.

  As a strain sensor, a strain gauge is generally used, but it is difficult to ensure accuracy, durability, heat resistance, and energy saving. Development of semiconductor strain sensors that satisfy these characteristics, and pressure sensors, vibration sensors, and acceleration sensors using the same are also underway.

  The semiconductor strain sensor can measure the target physical quantity by transmitting the change in the physical quantity of the measurement target to the element by bonding the element to the measurement target. For example, Patent Document 1 discloses a strain sensor using a piezoresistor. For example, Patent Document 2 discloses a pressure sensor that detects a natural frequency of a member.

  On the other hand, in order to realize energy saving when focusing on fields other than sensors, the use of power semiconductors for controlling electric power is advancing. The structure of a product using a power semiconductor is a form in which a semiconductor element is bonded to a substrate via a bonding material such as solder. In recent years, power semiconductors have been used in a high temperature range, and accordingly, higher melting point and higher reliability of solder joints are required.

JP 2006-3182 A JP 2012-118057 A JP 2005-32834 A

  A strain sensor is required to minimize changes in measured values with time. For example, if the measured value of the strain is 1 at a certain time and the strain to be measured has not changed after that, the measured value must be 1 even after a certain time has elapsed. However, when the sensor is used for a long time in a high temperature environment, creep (bonding phenomenon such as strain increases over time when sustained stress acts on the object) is applied to the bonding material such as adhesive or solder that joins the sensor to the measurement target. It will occur. For example, although the true strain of the object to be measured is 1, the solder creeps and is detected by the sensor as a strain of 0.9. When such a phenomenon occurs, it cannot be used as a sensor. Accordingly, the use conditions of the strain sensor are limited to a low temperature range, a strain range, and a time at which the bonding material does not cause creep.

  Also, the long-term reliability of the bonding material is important. In the case of products targeting automobiles, it is necessary to ensure reliability in the harsh environment of -55 ° C to 150 ° C. It is necessary to suppress the crack propagation of the joint material and the sensor characteristic variation with the temperature cycle.

  There is a need for joint materials and joining technologies that satisfy the above-mentioned creep resistance (characteristics that keep the creep of joint materials small within the practical temperature range of strain sensors) and long-term reliability. Generally, a high melting point bonding material is considered appropriate as such a bonding material. However, if the junction temperature exceeds 500 ° C., the performance of the semiconductor changes, which is not appropriate. In addition, it is necessary to use a material that does not crack the element due to thermal stress generated in the element when it is cooled to room temperature after bonding at a high temperature.

  In the joining technique described in Patent Document 3, the substrate is made of a low melting point metal material of tin, zinc, or indium on a wiring layer formed of a metal material of copper, copper alloy, or silver on the surface of the substrate. Disclosed is a bonding technique in which a low-melting-point metal layer is provided and the low-melting-point metal layer is diffused into the wiring layer by holding the pressure at a temperature equal to or higher than the melting point of the low-melting-point metal material for a certain period of time to diffuse the low-melting-point layer into the wiring layer. ing. This technique has a problem that the low melting point layer is expensive to be formed and it takes a long time to join. Further, the diffusion of the low melting point metal into the wiring layer causes a concentration gradient of the metal composition from the low melting point layer to the wiring layer, and there is a concern that reliability may be lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a low creep bonding material that is low in cost and improved in bonding property and bonding reliability, a bonding method using the bonding material, a bonding structure, and a semiconductor device.

  In order to solve the above-described problems, the present invention provides a Pb-free bonding material containing Ag and In, containing at least one kind of metal of Sb, Sn, Bi, and Zn, and the balance being inevitable impurities (Ag The ratio of (weight of In) :( In weight) :( total weight of Sb + Sn + Bi + Zn) is (70: 27: 3), (70: 5: 25), (10 : 2: 88), (10:45:45), the composition of the area inside the square connecting the points.

  Further, in order to solve the above-described problem, in the present invention, the bonding material is sandwiched between a first connected member and a second connected member, and the liquid temperature is equal to or higher than the solidus temperature of the bonding material. It was set as the joining method joined by heating to the temperature below phase wire temperature.

  In order to solve the above problems, in the present invention, the first connected member is used as an upper layer, and the second connected member having a larger area than the first connected member is used as a lower layer using the joining method. Bonding, and spreading the low melting point phase of the bonding material on the upper surface of the second connected member from the bonding portion directly below the first connected member to complete the bonding, With respect to the volume ratio of the low melting point phase / high melting point phase of the bonding material contained in the bonding portion immediately below the connected member, the low melting point phase / high melting point of the bonding material protruding from directly below the first connected member A junction structure characterized by a large volume ratio of phases was constructed.

  In order to solve the above problems, in the present invention, in the joining structure, the first connected member is a semiconductor strain sensor element, the second connecting member is a diaphragm, and the semiconductor strain sensor element is A semiconductor device that converts a change in pressure into an electric signal by distorting the diaphragm through a change in accordance with a change in pressure applied to the opposite surface of the diaphragm was configured.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor device with high creep resistance of a joining layer can be provided.

It is a figure which shows the structure of the semiconductor device joined by the joining method of this invention. It is a figure which shows the ratio of the solder composition of this invention. The inside of the solid line area is within the range of the composition in which the joining method of the present invention is established, and the inside of the dotted line area shows a range where low void joining can be realized. FIG. 4 is a diagram showing the solder composition of the present invention for samples No. 1 to No. 28 used in Example 2. It is a figure which shows the result of having evaluated joining temperature and a creep characteristic with respect to the solder composition shown in FIG. 3, and a comparative example. It is a figure which shows the cross-sectional structure | tissue of the sample which heated and joined Ag-In-Sb solder of this invention to 450 degreeC which is more than solidus temperature. It is a figure which shows the cross-sectional structure | tissue of the sample which heated and joined the Ag-In-Sb solder of this invention to 500 degreeC more than liquidus temperature. It is a figure which shows the structure of the semiconductor device which joined the semiconductor element, the stress relaxation material, and the board | substrate with the joining material and joining method of this invention. It is a figure which shows the structure of the semiconductor device (pressure sensor module) which joined the semiconductor strain sensor chip and the diaphragm with the joining material and joining method of this invention. It is a figure which shows the example of a state diagram of Ag-In-Sb solder.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  The inventor of the present application has focused attention on an Ag-based alloy whose main constituent element is Ag as a candidate for a creep-resistant and highly reliable solder. Ag has a melting point of 962 ° C., and has a melting point that is too high as a bonding material for semiconductors. Further, pure metal is easy to creep, and is therefore unsuitable as a bonding material with excellent creep resistance. However, it has been found that by using an Ag—In solid solution alloy in which Ag is mixed with In, the solidus temperature is lowered to about 700 ° C. and the creep resistance is improved. Nevertheless, if the junction temperature exceeds 700 ° C., it exceeds the heat resistance limit of the semiconductor element and cannot be applied to the junction. Thus, it has been found that by adding Sb, Sn, Bi, and Zn, the solidus temperature can be lowered to 500 ° C. or less, and bonding can be performed in a temperature range in which the semiconductor does not fail. That is, Pb-free Ag-In- (Sb + Sn + Bi + consisting of at least one metal and inevitable impurities (contaminants that are unavoidable industrially) from Ag and In and Sb, Sn, Bi, Zn The Zn) solder material was found as a bonding material having excellent creep resistance based on the experimental results described later. (Sb + Sn + Bi + Zn) represents at least one metal selected from Sb, Sn, Bi, and Zn.

A method of joining the semiconductor element 1 to the substrate 3 with the Ag—In— (Sb + Sn + Bi + Zn) solder material 2 of the present invention will be described. FIG. 1 shows a structural schematic diagram after bonding. Ag-In- (Sb + Sn + Bi
+ Zn) Prepare a sheet of solder 2. The substrate 3, the solder 2, and the semiconductor element 1 are stacked. The solder 2 is melted by flowing in a reflow furnace set so that the temperature of the solder is not lower than the solidus temperature and not higher than the liquidus temperature.

  FIG. 9 shows an example of a phase diagram of Ag-In-Sb solder (P. Villars, et.al., “Handbook of Ternary Alloy Phase Diagrams”, ASM international, vol. 3, p2490 ISBN: 0-87170-528-1 See more). In the case of the composition on the line 100 (Ag-25In-25Sb solder), it starts to melt at 424 ° C. (solid phase line) and ends at 466 ° C. (liquid phase line).

  By setting the temperature so that the temperature of the solder is not less than the solidus temperature and not more than the liquidus temperature, the low melting point phase 22 of the Ag-In- (Sb + Sn + Bi + Zn) solder 2 becomes a semiconductor element. It spreads out from directly under 1, and a part flows out. As a result, the ratio of the high melting point phase 21 in the bonding layer 9 immediately below the semiconductor element 1 is larger than that of the high melting point phase included in the initial solder material 2. In other words, bonding is possible in a temperature range where the semiconductor element does not fail, and after bonding, the creep resistance of the bonding layer 9 is improved as compared with the original solder material 2 (solid solution, intermetallic compound and eutectic coexist). . Here, the high melting point phase 21 is a phase in which In is dissolved in Ag and a phase of an In-Sb compound, and the low melting point phase 22 is an Ag-In- (Sb + Sn + Bi + Zn) solder. It is a eutectic phase with a low melting point in which the metals are mixed.

  The bonding atmosphere can be various atmospheres such as nitrogen, nitrogen + hydrogen, or formic acid. In addition to reflow, the bonding apparatus can be bonded using a die bonder by processing the solder into a ribbon or wire shape. That is, by pressing the solder ribbon wire against the heated substrate, the solder can be supplied onto the substrate and then the chip can be mounted. In this method, when the heating time is shortened and the low melting point phase is insufficiently discharged, an additional reflow may be performed thereafter.

  The composition of the Ag—In— (Sb + Sn + Bi + Zn) solder material of this example will be described in detail. Based on the experimental results described later, the proper ratio of Ag, In and Sb, Sn, Bi, Zn is shown in the ternary phase diagram of FIG. In order to realize the above-described joining, a solder having a composition within the range surrounded by the solid lines (101, 102, 103, 104) in FIG. 2 is appropriate. That is, Ag: In: (Sb + Sn + Bi + Zn) by weight ratio is (70: 27: 3), (70: 5: 25), (10: 2: 88), (10:45:45) It is a composition inside the rectangle which connects the points. Within this composition range, the solidus temperature becomes 160 ° C. to 490 ° C., and bonding can be performed without destroying the semiconductor element.

  In the region (1) above the boundary line 101 of the solid line in FIG. 2, the proportion of Ag is further increased, the melting point exceeds 550 ° C., and the temperature region where the semiconductor element is destroyed is reached. Further, in the region (2) on the right side of the boundary line 102, since the amount of In is too small and In does not sufficiently dissolve in Ag, the creep resistance is deteriorated. Further, in the region (3) below the boundary line 103, the amount of high melting point Ag is too small to obtain the creep resistance. Further, in the region (4) on the left side of the boundary line 104, the amount of In is too large, and a high creep phase with a low melting point is generated, and desired creep resistance characteristics cannot be obtained. Based on the above determination, the boundary lines (101, 102, 103, 104) are determined.

  Further, if the amount of the generated liquid phase is not more than a certain level, a lot of voids are generated at the time of joining, and the creep resistance is lowered. Therefore, in order to obtain a good bond having a void ratio of 10% or less, in which a liquid phase is sufficiently generated and the creep resistance is not deteriorated, the composition within the dotted line range of the ternary phase diagram of FIG. 2 is more appropriate. That is, Ag: In: (Sb + Sn + Bi + Zn) by weight ratio is (60:30:10), (60:15:25), (15:15:70), (15:43:42) It is a composition inside the rectangle which connects the points. Among them, regarding the ratio of Sb + Sn + Bi + Zn, when Sb is 80-100 wt.% And Sn + Bi + Zn is 0-20 wt.%, The solidus temperature becomes 400 ° C or more, and the creep resistance Is the maximum.

  The supply form of the solder material will be described. The Ag-In- (Sb + Sn + Bi + Zn) solder material can be supplied in the form of a sheet, a ribbon, a wire or the like as described above. Furthermore, a ball-shaped alloy can be made and supplied as a solder paste. At this time, Ag-In- (Sb + Sn + Bi + Zn) solder balls may be used, or a paste in which two kinds of Ag particles and In- (Sb + Sn + Bi + Zn) particles are mixed may be used. In that case, In- (Sb + Sn + Bi + Zn) particles are melted first, Ag particles are gradually dissolved, and finally behave as Ag-In- (Sb + Sn + Bi + Zn) solder.

  A substrate which is a material to be bonded will be described. The Ag—In— (Sb + Sn + Bi + Zn) solder material can obtain good bonding to various metals. For example, Cu, Ni, Au, Ag, Ti, SUS, Mo, W, Fe, Fe—Ni alloy and the like. In particular, from the viewpoint of wettability with the substrate, wettability with a Ni plate or a metal plate plated with Ni is excellent. From the viewpoint of bonding stability, bonding with a Cu plate or a metal plate plated with Cu is good. An underlayer such as Ti or W may be formed as a diffusion preventing layer between Cu and the substrate. Also, bonding with ceramics such as alumina, aluminum nitride, and silicon nitride is possible.

  On the other hand, the Ag—In— (Sb + Sn + Bi + Zn) solder material is a solder material that hardly creeps, in other words, a material that does not easily stretch. Therefore, when bonding a semiconductor element having a small coefficient of thermal expansion, if the substrate has a large coefficient of thermal expansion, the semiconductor element may break due to thermal stress when bonded and cooled. In that case, it is desirable to use a low thermal expansion material or a low thermal expansion intermediate material for the substrate, and examples of the low thermal expansion material include SUS, Mo, W, and Fe—Ni alloys. In addition, a multilayer clad substrate in which SUS and Mo are laminated may be used. In order to improve the wettability between the solder material and the metal plate, Cu or Ni metallization may be applied to the surface.

  In this example, the joint structure shown in FIG. 1 is produced using Ag—In— (Sb + Sn + Bi + Zn) solder materials having various compositions. An example of the produced Ag-In- (Sb + Sn + Bi + Zn) solder material is shown in FIG. Ag, In, Sb, Sb, Bi and Zn metals were mixed so as to have the composition indicated by the black circles in the figure, and heated to 960 ° C. or higher and dissolved, and ingot Nos. 1 to 28 (in FIG. 3). Corresponding to the numbers attached to the black circles). The ratio of each metal of Sb + Sn + Bi + Zn was 4 types of Sb100%, Sn100%, Bi100%, and Zn100%, and 112 kinds of compositions were produced in total. The ingot was processed into a sheet by rolling and used as solder. As the substrate 3, a SUS420 film formed of Ti and Cu in this order was used. The substrate 3, various types of solder, and a 2 mm □ semiconductor strain sensor chip 1 or a power semiconductor chip 1 were stacked. In a nitrogen + hydrogen mixed atmosphere, the temperature is higher than the respective solidus temperature and lower than the liquidus temperature. The temperature was raised to 200 ° C. to 490 ° C., the solder was melted, and heated and held for 1 min or more. It was confirmed that the low melting point phase 22 melted in the temperature range spreads out from the bonding layer 9 immediately below the semiconductor 1 on the substrate while being heated and flows out. About the sample which joined the semiconductor strain sensor chip 1, the creep characteristic was investigated using the sensor chip in 180 degreeC environment. As a representative, the test result in Ag-In-Sb solder is shown in FIG. As a result, when it was held at 180 ° C. for 100 hours while adding 500 μ strain, the fluctuation of the creep measurement value was 0.1% or less, and good characteristics could be obtained. In addition to the bonding material using Sb shown in FIG. 4, it was confirmed that the same results were obtained even when using a bonding material made of Sn, Bi, and Zn.

  For comparison, a sample was prepared by joining a substrate obtained by forming a Ni plating film on SUS420 and a semiconductor strain sensor chip using Au—Sn eutectic solder and Sn—Ag—Cu solder. When the same creep test was performed, a strain change exceeding 3% was measured, and the function as a bonding material for bonding the semiconductor strain sensor chip to the substrate was insufficient.

  In addition, when the Ag-In- (Sb + Sn + Bi + Zn) solder material of the present invention is used for bonding at a temperature higher than the liquidus temperature, the solder spreads cleanly, but the bonding layer directly under the device The composition outside the joining layer was only the same as the initial solder composition, and the effect of improving the creep resistance just under the joining layer was not obtained. As an example, FIG. 5 shows a cross-sectional structure of a bonding layer of a sample in which Ag—In—Sb solder is used and bonded at a temperature higher than the solidus temperature and lower than the liquidus temperature in the present invention, and FIG. The bonding layer cross-sectional structure of the sample bonded as described above is shown. In FIG. 6, the Ag—In—Sb eutectic phase, which is a low melting point phase, can be seen in the region of about 60% of the bonded cross section, but in FIG. 5, the Ag—In solid solution phase and the In—Sb intermetallic compound phase are almost 100%. Occupy. It was confirmed that the structure of FIG. 5 had better creep resistance.

  As described above, it has been found that Ag—In— (Sb + Sn + Bi + Zn) solder is useful as a creep-resistant solder because creep is suppressed even in a high temperature environment.

  Of the Ag-In- (Sb + Sn + Bi + Zn) solder shown in Example 2, when the proportion of Sb or Zn in the composition ratio of Sb + Sn + Bi + Zn exceeds 50%, The phase line temperature becomes 300 ° C or higher. In that case, depending on the size of the semiconductor element to be bonded, it was found that the semiconductor element was cracked by the thermal stress generated by cooling after bonding, particularly in the case of a thickness of 150 μm or more. Therefore, as shown in FIG. 7, the thermal expansion of the SUS (stainless steel) or Al substrate 3 and the Fe-Ni alloy plate, Mo, W, or CIC (Cu / Invar / Cu clad material) (silicon wafer, ceramic). The low thermal expansion material 4 of the semiconductor clad material having a high degree of consistency) is joined with the Ag-In- (Sb + Sn + Bi + Zn) solder 2 of the present invention, and the low thermal expansion material 4 and the semiconductor element 1 are further combined. Joined with 2 solder. At this time, the size of the low thermal expansion material 4 functioning as a stress relaxation layer is made larger than the size of the semiconductor element 1, so that the low melting point phase of the solder of the present invention is maintained when the temperature is kept above the solidus temperature and below the liquidus temperature. It was confirmed that 22 was eluted from directly under the element, and the ratio of the high melting point phase 21 contained in the bonding layer 9 immediately under the semiconductor element 1 was increased to improve the creep resistance. Similarly, in the bonding layer 10 of the substrate 3 and the low thermal expansion material 4, it was confirmed that the ratio of the high melting point phase 21 was increased and the creep resistance was improved.

  Further, the substrate 3 shown in FIG. 1 was manufactured as a substrate in which a SUS or Al substrate and a low thermal expansion material Fe—Ni alloy, Mo, or W substrate were bonded together. This substrate was manufactured by clad rolling. When this low thermal expansion material clad substrate, the solder of the present invention, and a semiconductor element were joined, it was found that, despite the composition having a joining temperature of 300 ° C. or higher, the thermal stress generated during cooling can be alleviated and chip cracking can be suppressed. It was. When the creep test was carried out, it was found that characteristics of 0.1% or less were obtained at 180 ° C and 100h. Furthermore, when a temperature cycle test at -55 / 150 ° C. was performed, it was found that there was no change in characteristics even after 1000 cyc.

  As described above, by using the low thermal expansion material, a thick chip can be joined without chip cracking.

The semiconductor strain sensor chip is connected using the solder of the present invention, and can be applied to the pressure sensor module shown in FIGS.
The pressure sensor module whose sectional view is shown in FIG. 8 (A) is connected to, for example, a hydraulic system piping of an automobile, and the semiconductor strain sensor chip 1 connected on the diaphragms 4 and 5 is connected to the diaphragm 4 according to the change in hydraulic pressure. , 5, the pressure change is converted into an electrical signal.

FIG. 8B shows an enlarged view of a connection portion in which the semiconductor strain sensor chip 1 is connected by the solder 2 of the present invention. As an example, the case of Ag-In-Sb solder will be described. To make a prototype, a 2 mm square semiconductor strain sensor chip, an Ag-In-Sb solder, a SUS diaphragm, a clad substrate diaphragm laminated with SUS / Mo, a clad substrate diaphragm laminated with SUS / 42Alloy, and a CIC substrate Prepared. There are two types of prototype structures.
One is a stack of SUS diaphragm, Ag-In-Sb solder, CIC substrate, Ag-In-Sb solder and chip in order. As shown in FIG. 7, the low thermal expansion material 4 is sandwiched between the semiconductor element 1 and the diaphragm 5 as a stress relaxation layer.
The other is a structure in which the clad substrate diaphragm 4,5 laminated with SUS / Mo, or the clad substrate diaphragm 4,5 laminated with SUS / 42Alloy, Ag-In-Sb solder, and semiconductor strain sensor chip 1 are sequentially stacked. It is.

  A 1 g weight was placed and heated in a nitrogen + hydrogen atmosphere to 450 ° C., which is not lower than the solidus temperature and not higher than the liquidus temperature, and held for 3 minutes for bonding. Chip cracking can be suppressed by the effect of CIC substrate and low thermal expansion clad substrate diaphragm, respectively.

  Furthermore, the electrode on the semiconductor strain sensor chip 1 and the printed circuit board 7 were connected by wire bonding 6 to manufacture a pressure sensor module 8 for medium and high pressure. This module has been confirmed to be able to measure pressure accurately by suppressing creep to 0.1% or less in a 180 ° C environment, which was impossible in the past.

  As described above, the present invention has been specifically described based on the embodiment of the invention. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say. That is, in the above description, the application of the present invention has been described by taking the semiconductor strain sensor chip and the power semiconductor chip as examples, but in addition, the present invention can be applied as bonding materials having various structures. As an application example, it can also be applied as an alternator diode, power module, LED, sealing lid, and thermoelectric conversion module.

1 ... Semiconductor element
2 ... Solder material
3 ... Board
4 ... Low thermal expansion material
5 ... Diaphragm
6 ... Wire
7 ... Printed circuit board
8 ... Pressure sensor module
9,10 ・ ・ ・ Junction layer
21 ... High melting point phase
22 ... Low melting point phase
100 ・ ・ ・ Ag-25In-25Sb solder state transition line
101,102,103,104 ・ ・ ・ Boundary line of appropriate proportion of area on ternary phase diagram

Claims (15)

A Pb-free bonding material containing Ag and In, including at least one kind of metal of Sb, Sn, Bi, and Zn, and the balance of inevitable impurities,
The ratio of (Ag weight) :( In weight) :( Total weight of Sb + Sn + Bi + Zn) is (70: 27: 3), (70: 5: 25) on the ternary phase diagram, (10: 2: 88), (10:45:45) A bonding material characterized by having a composition in a region inside a quadrilateral connecting points.   The bonding material according to claim 1, wherein the weight ratio of Sb, Sn, Bi, and Zn is 80% to 100% of Sb and 0% to 20% of the weight ratio of Sn + Bi + Zn. A bonding material characterized by   A paste-like bonding material in which Ag particles and In- (Sb + Sn + Bi + Zn) alloy particles are mixed, and each metal including the Ag particles and In- (Sb + Sn + Bi + Zn) alloy particles The paste-like bonding material is characterized in that the weight ratio of is the composition according to claim 1 or 2.   The bonding material according to any one of claims 1 to 3 is sandwiched between a first connected member and a second connected member, and the liquid is equal to or higher than the solidus temperature of the bonding material. A joining method for joining by heating to a temperature below the phase wire temperature. Using the joining method according to claim 4, the first connected member is joined to the upper layer, the second connected member having a larger area than the first connected member is joined to the lower layer, and the second connected member is joined. A joining structure in which the low melting point phase of the joining material is wetted and spread out from the joining portion directly below the first connected member on the upper surface of the connecting member, and the joining is completed.
The low melting point of the bonding material protruding from directly below the first connected member with respect to the volume ratio of the low melting point phase / high melting point phase of the bonding material contained in the bonding portion immediately below the first connected member. A junction structure characterized by a large volume ratio of the phase / high melting point phase.   The bonding method according to claim 4, wherein the first connected member is an upper layer, the second connected member having a larger area than the first connected member is a lower layer, and the first connected member. A third connected member having an area between the member and the second connected member is disposed in the intermediate layer, and the first connected member and the third connected member are formed using the bonding material. A joint structure characterized by joining a member and the third connected member and the second connected member. The joint structure according to claim 6,
Using the bonding method according to claim 4, the low melting point phase of the bonding material is wetted and spread outward from the bonding portion directly below the first connected member on the upper surface of the third connected member; and It is a structure in which the low melting phase of the bonding material is wetted and spread from the bonding portion directly below the third connected member to the upper surface of the second connected member to complete the bonding. Joining structure. Including Ag and In, including at least one of Sb, Sn, Bi, and Zn, with the balance being inevitable impurities, (Ag weight): (In weight): (Sb + Sn + Bi (Total weight of + Zn) on the ternary phase diagram (70: 27: 3), (70: 5: 25), (10: 2: 88), (10:45:45) Sandwiching the bonding material that is the composition of the inner region of the quadrangle connecting the first connected member as the upper layer and the second connected member as the lower layer,
Heating the laminate of the first connected member, the bonding material, and the second connected member to a temperature not lower than the solidus temperature of the bonding material and not higher than the liquidus temperature,
The bonding is completed by wetting and spreading the low melting point phase of the bonding material outwardly from the bonding portion directly below the first connected member on the upper surface or side surface of the second connected member. Joining method.   The weight ratio of Sb, Sn, Bi, and Zn in the bonding material is such that Sb is 80% to 100% and the weight ratio of Sn + Bi + Zn is 0% to 20%. The joining method described in 1.   The bonding material is a paste-like bonding material in which Ag particles and In- (Sb + Sn + Bi + Zn) alloy particles are mixed, wherein the Ag particles and the In- (Sb + Sn + Bi + Zn) alloy particles The joining method according to claim 8, wherein the weight ratio of each of the metals is the composition according to claim 8.   The joining structure according to any one of claims 5 to 7, wherein the first connected member is a semiconductor element, and the second connected member is a metal or ceramics. Joining structure.   The joining structure according to claim 6 or 7, wherein both surfaces of the third connecting member are Cu.   The semiconductor device according to claim 11, wherein the semiconductor device is a power semiconductor.   12. The semiconductor device according to claim 11, wherein the semiconductor element is a semiconductor strain sensor element.   The joining structure according to any one of claims 5 to 7, wherein the first connected member is a semiconductor strain sensor element, the second connecting member is a diaphragm, and the semiconductor strain sensor element is A semiconductor device characterized in that a change in pressure is converted into an electric signal by distorting through the diaphragm in accordance with a change in pressure applied to the opposite surface of the diaphragm.

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