Patent Publication Number: US-2021166989-A1

Title: Structure and bonded body

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application of International Patent Application PCT/JP2020/009944, filed on Mar. 9, 2020. This application also claims priority to Japanese Patent Application 2019-168557, filed on Sep. 17, 2019. The entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described herein relate generally to a structure and a bonded body. 
     BACKGROUND 
     There is a structure including silicon nitride. It is desired that thermal conductivity or flexural strength of the structure is high. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view illustrating a structure according to an embodiment; 
         FIG. 2  is graphs illustrating analysis results of the structure according to the embodiment; 
         FIG. 3  is a graph illustrating analysis results of a structure according to a reference example; 
         FIG. 4  is a graph illustrating analysis results of a structure according to a reference example; 
         FIG. 5  is a graph illustrating analysis results of a structure according to a reference example; 
         FIGS. 6A and 6B  are perspective views illustrating the structure according to the embodiment; and 
         FIG. 7  is a schematic cross-sectional view illustrating a bonded body according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a structure according to the embodiment includes a β type silicon nitride type crystal phase and a Y 2 Si 3 O 3 N 4  type crystal phase. In an X-ray diffraction pattern according to a θ-2θ method of the structure, a ratio of a second peak intensity being maximum and appearing at 2θ=31.93±0.1° with respect to a first peak intensity being maximum and appearing at 2θ=27.03±0.1° is 0.005 or more and 0.20 or less. 
     The embodiment of the invention will now be described with reference to the drawings. 
       FIG. 1  is a schematic cross-sectional view illustrating the structure according to the embodiment. 
     A structure  110  according to the embodiment includes crystal grains  10  and grain boundaries  20  provided around the crystal grains  10 , as illustrated in  FIG. 1  a plurality of crystal grains  10  exist in the grain boundary  20 . The plurality of crystal grains  10  in the grain boundary  20  may be spaced from each other or may partially contact each other. A part of the plurality of crystal grains  10  may be separated from each other, and another part of the plurality of crystal grains  10  may partially contact each other. 
     The crystal grain  10  includes a β type silicon nitride type crystal phase. The grain boundary  20  includes yttrium, silicon, oxygen, and nitrogen. For example, the grain boundary  20  includes a Y 2 Si 3 O 3 N 4  type crystal phase. The Y 2 Si 3 O 3 N 4  Type crystal refers to a crystal having the same crystalline structure as that of Y 2 Si 3 O 3 N 4 . Here, the same crystalline structure means that a crystal system, a space group, and a positional relationship of constituent atoms are the same, and an interatomic distance or a lattice constant may not necessarily be equal. Also, an element included in the crystalline phase does not matter. That is, a composition of the Y 2 Si 3 O 3 N 4  type crystal phase may be different from that of Y 2 Si 3 O 3 N 4 . 
       FIG. 2  is graphs illustrating analysis results of the structure according to the embodiment. 
       FIG. 2  illustrates an X-ray diffraction pattern according to the θ-2θ method of the structure according to the embodiment. The horizontal axis represents 2θ. The vertical axis represents a normalized intensity. 
     Conditions in measuring the X-ray diffraction pattern are set as follows, for example. X-ray diffraction according to a concentration method (reflection method, Bragg-Brendano method) is performed using an X-ray diffraction apparatus, for example, Smart-Lab (manufactured by Rigaku Corporation). In the X-ray diffraction, any cross-section of the structure is taken as a measurement surface. The measurement surface is polished such that a surface roughness Ra is 0.05 μm or less. A Cu target (Cu—Kα) is used for the measurement. A tube voltage is set to 45 kV. A tube current is set to 200 mA. A scanning speed is set to 2.0 to 20.0°/min. An incident parallel slit is set to 5 degrees, a longitudinal restriction slit is 10 mm, a light receiving slit is set to 20 mm, and a light receiving parallel slit is set to 5 degrees. A scanning range (2θ) is set to 10° to 80° and the measurement is performed in increments of 0.01°. 
     In  FIG. 2 , each of the top three graphs indicates the corresponding analysis result for samples 1 to 3. In the analysis results, a peak pointed with a black triangular arrow (▾) is attributed to the β type silicon nitride type crystal phase. A peak pointed with a white triangular arrow (∇) is attributed to the Y 2 Si 3 O 3 N 4  type crystal phase. A peak pointed with a triangular arrow with dots is attributed to a jig used in the measurement. 
     The graph on the bottom (right of the page) illustrates diffraction patterns of the β type silicon nitride (β-Si 3 N 4 ) type crystal phase, the Y 2 Si 3 O 3 N 4  type crystal phase, and a material of the jig. A line with a black diamond shape (♦) indicates an angle at which a peak of the β type silicon nitride type crystal phase appears. A line with a white diamond shape (⋄) indicates an angle at which a peak of the Y 2 Si 3 O 3 N 4  type crystal phase appears. A line with a black circle (●) indicates an angle at which a peak attributed to the jig appears. Here, a pattern included in Powder Diffraction File provided by International Centre for Diffraction Data (trademark) is used. 
     The samples 1 to 3 are manufactured by the same method under the same conditions as one another. As illustrated in  FIG. 2 , with the structure according to the embodiment, a peak P 1  appears at 27.03±0.1° for the β type silicon nitride type crystal phase. A peak P 2  appears at 31.93±0.1° for the Y 2 Si 3 O 3 N 4  type crystal phase. 
     For the sample 1, a ratio of the second peak intensity being maximum and appearing at 31.93±0.1° with respect to the first peak intensity being maximum and appearing at 27.03±0.1° is 0.13. For the sample 2, a ratio of the second peak intensity with respect to the first peak intensity is 0.12. For the sample 3, a ratio of the second peak intensity with respect to the first peak intensity is 0.10. This is because an abundance ratio of the Y 2 Si 3 O 3 N 4  type crystal phase with respect to the β type silicon nitride (β-Si 3 N 4 ) type crystal phase is relatively low. 
     When a plurality of peaks appear at 27.03±0.1° or 31.93±0.1°, the ratio is calculated using a peak having the highest intensity. Hereinafter, when a plurality of peaks appear within a specific range of angles, each ratio to be described below is calculated using a peak with the highest intensity. 
     A peak P 3  also appears at 33.63±0.1° for the β type silicon nitride type crystal phase. A peak P 4  appears at 29.67±0.1° for the Y 2 Si 3 O 3 N 4  type crystal phase. 
     For sample 1, a ratio of a fourth peak intensity being maximum and appearing at 29.67±0.1° with respect to a third peak intensity being maximum and appearing at 33.63±0.1° is 0.14. For sample 2, a ratio of a fourth peak intensity with respect to a third peak intensity is 0.12. For sample 3, a ratio of a fourth peak intensity with respect to a third peak intensity is 0.09. 
     Furthermore, a peak P 5  also appears at 36.04±0.1° for the β type silicon nitride type crystal phase. A peak P 6  also appears at 38.36±0.1° for the Y 2 Si 3 O 3 N 4  type crystal phase. 
     For sample 1, a ratio of a sixth peak intensity being maximum and appearing at 38.36±0.1° with respect to a fifth peak intensity being maximum and appearing at 36.04±0.1° is 0.07. For sample 2, a ratio of a sixth peak intensity with respect to a fifth peak intensity is 0.07. For sample 3, a ratio of a sixth peak intensity with respect to a fifth peak intensity is 0.07. 
     Next, a method of manufacturing the structure according to the embodiment will be described. 
     Si of 100 mol % expressed in terms of Si 3 N 4 , Y 2 O 3  of 2 mol %, and MgO of 5 mol % are weighed. Y 2 O 3  and MgO are used as auxiliary agents. In addition, B 2 O 3  may be used as the auxiliary agent, and each of these auxiliary agents may be used alone, or a plurality of the auxiliary agents may be mixed and used. A percentage of the auxiliary agents is favorably not lower than 2 mol % and not higher than 20 mol % expressed in terms of Si 3 N 4 . 
     These materials are ground and mixed by using a planetary ball mill for not shorter than 0.2 hours and not longer than 6 hours. When the grinding time is too short, grain diameters of the materials are too large, and strength of the structure decreases, which is not favorable. When the grinding time is too long, the grain diameters of the materials become too small, and thermal conductivity decreases, which is not favorable. 
     Next, granulation is performed by drying the mixture and adding a binder. At this time, polyvinyl butyl alcohol, acrylic resin, or the like may be used as the binder. These binders may be used alone or a plurality of different binders may be mixed. Not less than 1 wt % and not more than 20 wt % of the binder with respect to the total amount is favorably added. When the binder is less than 1 wt %, the materials are hardly bound to each other, and the strength of the structure decreases, which is not favorable. When the binder is larger than 20 wt %, an amount of the binder in the structure becomes too large, and the thermal conductivity of the structure decreases, which is not favorable. 
     Thereafter, by applying a pressure of not lower than 0.5 t/cm 2  and not higher than 10 t/cm 2 , molding is performed. The pressure is adjusted depending on the materials. A molded body is degreased in the air at a temperature of not lower than 300° C. and not higher than 800° C., and then is processed in a nitrogen atmosphere at not lower than 1000° C. and not higher than 1500° C. The processing time for the degreasing and the processing time at the nitrogen atmosphere are adjusted depending on the processing temperature. 
     Thereafter, the structure according to the embodiment may be obtained by sintering for not shorter than 1 hour and not longer than 200 hours at a temperature of not lower than 1700° C. and not higher than 2100° C. 
     An example of the method of manufacturing the structure according to the embodiment will be described. The example is a method of manufacturing the sample 1. 
     Si of 100 mol % expressed in terms of Si 3 N 4 , Y 2 O 3  of 2 mol %, and MgO of 5 mol % are weighed. Y 2 O 3  and MgO are used as auxiliary agents. These materials are ground and mixed for 1 hour by using a planetary ball mill. The granulation is performed by drying the mixture and adding 5 wt % of polyvinyl butyl alcohol as a binder. Then, by adding a pressure of 1 t/cm 2 , molding is performed. A molded body is degreased in the air at 500° C. and then is processed for 8 hours at 1400° C. in a nitrogen atmosphere. Sintering is then performed at 1900° C. for 24 hours to fabricate a sintered body. Thus, the structure according to the embodiment may be obtained. 
     In manufacturing of the sample 2, mixing time of raw materials is different from that of manufacturing of the sample 1. In manufacturing of the sample 3, a ratio of auxiliary agents is different from that of the manufacturing of the sample 1. The samples 2 and 3 were fabricated in the same manner as sample  1 , except for these points. 
       FIG. 3  to  FIG. 5  are graphs illustrating analysis results of structures according to reference examples. 
       FIG. 3  to  FIG. 5  illustrate X-ray diffraction patterns according to the θ-2θ method of the structures according to the reference examples. Each of the horizontal axes represents 2θ. Each of the vertical axes represents a normalized intensity. The upper graph in each of  FIG. 3  to  FIG. 5  illustrates the analysis results for samples. The lower graph in each of  FIG. 3  to  FIG. 5  (right of the page) illustrates the X-ray diffraction patterns according to the θ-2θ method. 
     In the analysis results illustrated in  FIG. 3 , a peak pointed with a black triangular arrow (▾) is attributed to a crystal of β type silicon nitride. A peak pointed with a white triangular arrow (∇) is attributed to a crystal of Y 4 Si 2 O 7 N 2 . A peak pointed with a triangular arrow with dots is attributed to a jig used in the measurement. 
     The lower graph (right of the page) in  FIG. 3  illustrates diffraction patterns of β type silicon nitride (β-Si 3 N 4  type crystal phase), a Y 4 Si 2 O 7 N 2  type crystal phase, and a material of the jig. A line with a black diamond shape (♦) indicates an angle at which a peak of β-type silicon nitride appears. A line with a white diamond shape (⋄) indicates an angle at which a peak of Y 4 Si 3 O 3 N 4  appears. A line with a black circle (●) indicates an angle at which a peak attributed to the jig appears. 
     In the structure according to the embodiment, the Y 2 Si 3 O 3 N 4  type crystal phase is detected in addition to the β type silicon nitride (β-Si 3 N 4 ) type crystal phase. In contrast, in a structure according to a first reference example, no Y 2 Si 3 O 3 N 4  type crystal phase is detected, and as illustrated in  FIG. 3 , a Y 4 Si 2 O 7 N 2  type crystal phase is detected. 
     In the analysis results illustrated in  FIG. 4 , a peak pointed with a black triangular arrow (▾) is attributed to the β type silicon nitride type crystal phase. A peak pointed with a white triangular arrow (∇) is attributed to an a type silicon nitride (α-Si 3 N 4 ) type crystal phase. A peak pointed with a triangular arrow with dots is attributed to the material of the jig. 
     The lower graph (right of the page) in  FIG. 4  illustrates a diffraction pattern of the β type silicon nitride (β-Si 3 N 4 ) type crystal phase, a diffraction pattern of the a type silicon nitride (α-Si 3 N 4 ) type crystal phase, and a diffraction pattern of the material of the jig. A line with a black diamond shape (♦) indicates an angle at which a peak of the β type silicon nitride type crystal phase appears. A line with a white diamond shape (⋄) indicates an angle at which a peak of the a type silicon nitride type crystal phase appears. A line with a black circle (●) illustrates an angle at which a peak attributed to the material of the jig appears. 
     In a structure according to a second reference example, as illustrated in  FIG. 4 , a peak attributed to a compound including yttrium does not appear. In addition, the peaks attributed to the a type silicon nitride type crystal phase appear. 
     In the analysis results illustrated in  FIG. 5 , a peak pointed with a black triangular arrow (▾) is attributed to the β type silicon nitride type crystal phase. A peak pointed with a white triangular arrow (∇) is attributed to a Y 2 Si 3 N 6  type crystal phase. A peak pointed with a triangular arrow with dots is attributed to a material of a jig. 
     The lower graph (right of the page) in  FIG. 5  illustrates a diffraction pattern of the β type silicon nitride (β-Si 3 N 4 ) type crystal phase, a diffraction pattern of the Y 2 Si 3 N 6  type crystal phase, and a diffraction pattern of the material of the jig. A line with a black diamond shape (♦) indicates an angle at which a peak of the β type silicon nitride type crystal phase appears. A line with a white diamond shape (⋄) indicates an angle at which a peak of the Y 2 Si 3 N 6  type crystal phase appears. A line with a black circle (●) illustrates an angle at which a peak attributed to the material of the jig appears. 
     In a structure according to a third reference example, no Y 2 Si 3 O 3 N 4  type crystal phase is detected, and as illustrated in  FIG. 5 , a Y 2 Si 3 N 6  type crystal phase is detected. 
     The structure according to the first reference example illustrated in  FIG. 3  is manufactured using powder of Si 3 N 4  instead of powder of Si. That is, Si 3 N 4 , Y 2 O 3 , and MgO are ground and mixed. The mixture is dried and granulated by adding a binder. By degreasing after molding and further sintering, the structure according to the first reference example is obtained. 
     The structure according to the second reference example illustrated in  FIG. 4  and the structure according to the third reference example illustrated in  FIG. 5  are manufactured using powder of Si, similarly to the structure according to the embodiment. After grinding and mixing Si, Y 2 O 3 , and MgO, molding is performed without adding a binder. By degreasing after the molding and further sintering, the structures according to the second reference example and the third reference example are obtained. Between the structures according to the second reference example and the structure according to the third reference example, conditions of mixing raw materials in a planetary ball mill are different. 
     Thermal conductivity and flexural strength of each of the structures according to the embodiment and the respective reference examples are measured. The thermal conductivity is measured in accordance with JIS-R-1611. JIS-R-1611 corresponds to ISO18755 (2005). The thermal conductivity is measured by a laser flash method by using a flash analyzer LFA 467 HyperFlash manufactured by NETZSCH Holding. 
     The flexural strength is measured by a three-point flexural strength test in accordance with JIS-R-1601. JIS-R-1601 corresponds to ISO14704 (2000). An autograph AG-X (100 kN) manufactured by Shimadzu Corporation is used for the three-point flexural strength test. A load cell is set to 1 kN, a test speed is set to 0.5 mm/min, both an indenter radius and a support base radius are set to R2, a distance between fulcrums is set to 30 mm, and the three-point flexural strength test is performed at room temperature. 
     The thermal conductivities of the samples 1 to 3 illustrated in  FIG. 2  are 120 W/(m·K), 121 W/(m·), 123 W/(m·K), respectively. According to the embodiment, the thermal conductivity of any of the structures is not lower than 120 W/(m·K). The thermal conductivity of the structure according to the first reference example is 86 W/(m·K). The thermal conductivity of the structure according to the second reference example is 70 W/(m˜K). The thermal conductivity of the structure according to the third reference example is 127 W/(m·K). 
     The flexural strength of the structure according to the embodiment is 350 MPa. The flexural strength of the structure according to the first reference example is 800 MPa. The flexural strength of the structure according to the second reference example is 100 MPa. The flexural strength of the structure according to the third reference example is 200 MPa. 
     As described above, the thermal conductivity of the structure according to the embodiment is higher than the thermal conductivity of the structure according to the first reference example or the second reference example. The thermal conductivity of the structure according to the third reference example is equivalent to the thermal conductivity of the structure according to the embodiment. However, the flexural strength of the structure according to the third reference example is inferior to the flexural strength of the structure according to the embodiment. 
     Furthermore, the flexural strength of the structure according to the embodiment is higher than the thermal conductivity of the structure according to the second reference example or the third reference example. The flexural strength of the structure according to the first reference example is higher than the flexural strength of the structure according to the embodiment. However, the thermal conductivity of the structure according to the first reference example is inferior to the thermal conductivity of the structure according to the embodiment. 
     That is, the structure according to the embodiment has excellent thermal conductivity and flexural strength. For example, according to the embodiment, the thermal conductivity of the structure may be not lower than 100 (m·K) and the flexural strength may be not lower than 300 MPa. 
     As illustrated in  FIG. 2 , in the structure according to the embodiment, the β type silicon nitride type crystal phase and the Y 2 Si 3 O 3 N 4  type crystal phase are included. On the other hand, in the structures according to the first reference example to the third reference example, the a type silicon nitride type crystal phase, the Y 4 Si 2 O 7 N 2  type crystal phase, or the Y 2 Si 3 N 6  type crystal phase is included. In the structures according to the first reference example to the third reference example, the Y 2 Si 3 O 3 N 4  type crystal phase is not included. Therefore, it is considered that improvement of properties due to the embodiment is attributed to the structure including the β type silicon nitride type crystal phase and the Y 2 Si 3 O 3 N 4  type crystal phase. For example, as illustrated in  FIG. 2 , with the structure according to the embodiment, a ratio of the second peak intensity with respect to the first peak intensity is not lower than 0.005 and not higher than 0.20. In other words, the ratio is 0.005 or more and 0.20 or less. It is considered that including the Y 2 Si 3 O 3 N 4  type crystal phase in the grain boundary in such a manner that the ratio is not lower than 0.005 improves properties of the structure. 
     The Y 2 Si 3 O 3 N 4  type crystal phase has a ratio of the number of oxygen atoms with respect to the number of nitrogen atoms of about 0.75.The Y 4 Si 2 O 7 N 2  type crystal phase has a ratio of the number of oxygen atoms with respect to the number of nitrogen atoms of about 3.5. The Y 2 Si 3 N 6  type crystal phase has a ratio of the number of oxygen atoms with respect to the number of nitrogen atoms of about 0. It is considered to be important that an oxygen concentration in the grain boundary of the structure is not too high or not too low to form the Y 2 Si 3 O 3 N 4  type crystal phase. When oxygen is appropriately present in the grain boundary of the structure, excellent thermal conductivity and high flexural strength can be achieved. This is considered to be attributed to the excellent thermal conductivity and the high flexural strength of the Y 2 Si 3 O 3 N 4  type crystal phase. 
     As for the structure according to the embodiment, granulation is performed by adding a binder to a mixture obtained by grinding in manufacturing. It is considered that addition of this process more evenly disperses oxygen in a process of manufacturing the structure and facilitates formation of the Y 2 Si 3 O 3 N 4  type crystal phase. For example, it is considered that due to occurrence of a bias in the oxygen concentration, formation of the Y 4 Si 2 O 7 N 2  type crystal phase and the Y 2 Si 3 N 6  type crystal phase in the grain boundary may be suppressed. 
     As described above, with the structure according to the embodiment, the ratio of the second peak intensity with respect to the first peak intensity is not lower than 0.005 and not higher than 0.20. Favorably, the ratio is not lower than 0.005 and not higher than 0.17. Preferably, the ratio is not lower than 0.005 and not higher than 0.14. By setting an amount of the Y 2 Si 3 O 3 N 4  type crystal phase in the grain boundary within these optimal ranges, both of high thermal conductivity and high flexural strength can be achieved. 
     In the structure according to the embodiment, the ratio of the fourth peak intensity with respect to the third peak intensity is not lower than 0.00 and not higher than 0.20. Favorably, the ratio is not lower than 0.00 and not higher than 0.18. Preferably, the ratio is not lower than 0.00 and not higher than 0.15. By setting the amount of the Y 2 Si 3 O 3 N 4  type crystal phase in the grain boundary within these optimal ranges, both of high thermal conductivity and high flexural strength can be achieved. 
     In the structure according to the embodiment, the ratio of the sixth peak intensity with respect to the fifth peak intensity is not lower than 0.00 and not higher than 0.20Favorably, the ratio is not lower than 0.00 and not higher than 0.15. Preferably, the ratio is not lower than 0.00 and not higher than 0.10. By setting the amount of the Y 2 Si 3 O 3 N 4  type crystal phase in the grain boundary within these optimal ranges, both of high thermal conductivity and high flexural strength can be achieved. 
     When these ratios are within the ranges described above, the thermal conductivity and the flexural strength of the structure can be improved. 
     As for the Y 2 Si 3 O 3 N 4  type crystal phase, a full width at half maximum of each of the peaks P 2 , P 4 , and P 6  illustrated in  FIG. 2  is favorably 0.25° or less. Due to high crystallinity of the Y 2 Si 3 O 3 N 4  type crystal phase in such a manner that the full width at half maximum is not larger than 0.25°, the thermal conductivity and the flexural strength of the structure can be further improved. 
     Each of  FIGS. 6A and 6B  is a perspective view illustrating the structure according to the embodiment. 
     For example, as illustrated in  FIGS. 6A and 6B , the structure according to the embodiment is a substrate. A shape of the substrate is arbitrary. As described above, the structure according to the embodiment has high thermal conductivity and high flexural strength. Thus, the structure according to the embodiment may be suitably used as the substrate. Alternatively, the structure according to the embodiment may be a bearing or the like. 
       FIG. 7  is a schematic cross-sectional view illustrating a bonded body according to the embodiment. 
     A bonded body  210  according to the embodiment includes a first metal part  31  and the structure  110 , as illustrated in  FIG. 7 . In the example, the structure  110  is used as a substrate. 
     The first metal part  31  is bonded to the structure  110 . For example, a bonding part  41  is provided between the first metal part  31  and the structure  110 . The first metal part  31  may be directly bonded to the structure  110  without the bonding part  41  interposed between the first metal part  31  and the structure  110 . 
     In the example illustrated in  FIG. 7 , the bonded body  210  further includes a second metal part  32  and a semiconductor device  50 . The semiconductor device  50  is bonded to the first metal part  31 . The first metal part  31  is positioned between the structure  110  and the semiconductor device  50 . For example, the bonding part  42  is provided between the semiconductor device  50  and the first metal part  31 . The semiconductor device  50  may be directly bonded to the first metal part  31  without the bonding part  42  interposed between the semiconductor device  50  and the first metal part  31 . 
     The second metal part  32  is bonded to the structure  110 . The structure  110  is positioned between the first metal part  31  and the second metal part  32 . For example, a bonding part  43  is provided between the second metal part  32  and the structure  110 . The second metal part  32  may be directly bonded to the structure  110  without the bonding part  43  between the second metal part  32  and the structure  110 . The second metal part  32  functions as a heat sink, for example. 
     The first metal part  31  and the second metal part  32  include at least one selected from the group consisting of copper and aluminum, for example. The bonding parts  41  to  43  include at least one selected from the group consisting of silver and copper, for example. The bonding parts  41  to  43  may further include at least one selected from the group consisting of titanium, hafnium, zirconium, niobium, silicon, magnesium, indium, tin, and carbon. The semiconductor device  50  includes, for example, a diode, a MOSFET, or an IGBT. 
     The bonding parts  41  to  43  favorably include active metal. For example, when the first metal part  31  and the second metal part  32  include copper, the active metal is at least one selected from the group consisting of titanium, hafnium, zirconium, and niobium. The bonding parts  41  to  43  favorably include silver, copper and at least one selected from the group consisting of titanium, hafnium, zirconium, and niobium. 
     When the first metal part  31  and the second metal part  32  include aluminum, the active metal is at least one selected from the group consisting of silicon and magnesium. The bonding parts  41  to  43  favorably include silver, copper, and at least one selected from the group consisting of silicon and magnesium. 
     When the first metal part  31  and the second metal part  32  include copper, titanium is particularly preferable as the active metal. Titanium can be reacted with silicon nitride to form titanium nitride, thereby increasing bonding strength. 
     The use of the structure  110  according to the embodiment in the bonded body  210  can improve the thermal conductivity and the flexural strength of the bonded body  210 . Furthermore, by using the structure  110  having excellent thermal conductivity in the substrate, it is possible to improve heat dissipation of the substrate, for example. In addition, the structure  110  has excellent flexural strength. Thus, it is possible to thin the substrate while maintaining the strength of the substrate. It is thereby possible, for example, to further improve the heat dissipation of the substrate. 
     According to the embodiment described above, the structure and the bonded body may be provided that can improve the thermal conductivity and the flexural strength. 
     Hereinabove, exemplary embodiments of the invention are described with reference to specific examples. However, the embodiments of the invention are not limited to these specific examples. For example, one skilled in the art may similarly practice the invention by appropriately selecting specific configurations of components such as structures, metal parts, bonding parts, semiconductor elements, etc., from known art. Such practice is included in the scope of the invention to the extent that similar effects thereto are obtained. 
     Further, any two or more components of the specific examples may be combined within the extent of technical feasibility and are included in the scope of the invention to the extent that the purport of the invention is included. 
     Moreover, all structures, and bonded bodies practicable by an appropriate design modification by one skilled in the art based on the structures, and the bonded bodies described above as embodiments of the invention also are within the scope of the invention to the extent that the purport of the invention is included. 
     Various other variations and modifications can be conceived by those skilled in the art within the spirit of the invention, and it is understood that such variations and modifications are also encompassed within the scope of the invention. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.