JP7018267B2 - Sialon sintered body, its manufacturing method, composite substrate and electronic device - Google Patents

Description

The present invention relates to a Sialon sintered body, a method for producing the same, a composite substrate and an electronic device.

Sialon is a general term for substances represented by the general formula: Si _6-z Al _z O _z N _8-z (0 <z ≤ 4.2), and among ceramic materials, it has high strength, high Young's modulus, and low thermal expansion. , A material that also has high insulation. When such a ceramic material is used as a support substrate for a composite substrate of an elastic wave element, it is required that there are no pores for bonding, the surface flatness is high, and the composition is uniform over the entire surface. As shown in Patent Document 1, in order to produce Sialon, it is common to fire using a sintering aid. On the other hand, a method of firing without using a sintering aid when producing Sialon is also known. For example, Patent Document 2 discloses a method of covering β-sialon with a powder of silicon nitride and BN and firing in an N ₂ gas atmosphere. Further, in Patent Document 3, aluminum alkoxide is added to silicon nitride powder, and after hydrolysis, the powder obtained by filtration is calcined at 600 to 900 ° C. and pressure-sintered at 1700 to 1900 ° C. to β. -A method for obtaining a Sialon sintered body is disclosed.

Japanese Unexamined Patent Publication No. 1-264973 Japanese Unexamined Patent Publication No. 61-141671 Japanese Unexamined Patent Publication No. 60-108371

However, when a sintering aid is used at the time of producing Sialon as in Patent Document 1, there is a problem that the composition is not uniform, the number of different phase components increases, and the number of pores increases. When the amount of the heterogeneous component increases, the easiness of polishing differs between the sialon and the heterogeneous component, so that there is a problem that the surface flatness is not sufficiently high. For example, when the heterogeneous component is harder than Sialon, the heterogeneous component is difficult to be polished and therefore tends to remain convex, and when the heterogeneous component is soft, the heterogeneous component is easily polished and easily becomes a hole. Further, if there are many pores in the material, there is a problem that the surface flatness is not sufficiently high because the recesses derived from the pores remain even after polishing. Further, as in Patent Documents 2 and 3, when normal pressure firing is performed without using a sintering aid during the production of Sialon, since Sialon is a difficult-to-sinter material, the pores are not completely discharged to the outside and remain inside. It was easy and it was difficult to make the relative density sufficiently high.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a Sialon sintered body having high surface flatness when the surface is mirror-polished.

The Sialon sintered body of the present invention is represented by Si _6-z Al _z O _z N _8-z (0 <z ≦ 4.2), has an open porosity of 0.1% or less, and has a relative density of 99.9. % Or more, and in the X-ray diffraction pattern, the ratio of the sum of the maximum peak intensities of each component other than sialon to the maximum peak intensity of sialon is 0.005 or less. Since this Sialon sintered body has a low open porosity, a high relative density, and few heterogeneous phases, the surface flatness when the surface is mirror-polished is high.

In the method for producing the Sialon sintered body of the present invention, Si: Al: O: N = (6-z) is selected from the components of silicon nitride, aluminum nitride, alumina and silica having a purity of 99.8% by mass or more. : Z: z: (8-z) (However, 0 <z≤4.2), the composition is selected, the mass ratio is determined, and each component is mixed to prepare a raw material powder, and the raw material powder is prepared. Is molded into a predetermined shape, and then hot-press fired at a firing temperature of 1725 to 1900 ° C. and a press pressure of 100 to 300 kgf / cm ² to obtain a sialon sintered body. This production method is suitable for producing the above-mentioned Sialon sintered body of the present invention because densification can be promoted while discharging pores by pressure.

The composite substrate of the present invention is a composite substrate in which a support substrate and a functional substrate are bonded, and the support substrate is the above-mentioned Sialon sintered body of the present invention. In this composite substrate, since the support substrate is the sialon sintered body of the present invention described above, the ratio of the area actually bonded to the bonding interface is large, and good bonding properties are exhibited.

The electronic device of the present invention utilizes the composite substrate of the present invention described above. In this electronic device, the coefficient of thermal expansion of the Sialon sintered body, which is the support substrate, is 3.0 ppm / K (40-400 ° C) or less, so that the frequency temperature dependence and filter performance of the surface acoustic wave device are high. It will be greatly improved. Further, in a Lamb wave element, a thin film resonator (FBAR), an LED device, an optical waveguide device, a switch device, a semiconductor device, etc., the thermal expansion coefficient of the support substrate is very small, so that the performance is improved. Furthermore, by adjusting the composition of Sialon (z value described above), Young's modulus can be adjusted while the coefficient of thermal expansion remains 3.0 ppm / K or less, which makes it functional when a composite substrate is formed. It is possible to fine-tune and maximize the performance of the board.

The perspective view of the composite board 10. FIG. 3 is a perspective view of an electronic device 30 manufactured by using the composite substrate 10.

Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to the following embodiments and is based on ordinary knowledge of those skilled in the art to the extent that it does not deviate from the gist of the present invention. It should be understood that changes, improvements, etc. will be made as appropriate.

The Sialon sintered body of the present embodiment is represented by Si _6-z Al _z O _z N _8-z (0 <z ≦ 4.2), has an open porosity of 0.1% or less, and has a relative density of 99. 9% or more (preferably 99.95% or more), and in the X-ray diffraction pattern, the ratio of the sum of the maximum peak intensities of each component (heterogeneous component) other than sialon to the maximum peak intensity of sialon is 0. It is less than 005. The measurement conditions of the X-ray diffraction pattern are CuKα, 40 kV, 40 mA, 2θ = 10-70 °. Since this Sialon sintered body has a low open porosity, a high relative density, and few heterogeneous phases, the surface flatness when the surface is mirror-polished is high. If the open porosity is high or the relative density is low, the surface flatness will not be sufficiently high because the recesses derived from the pores will remain even after polishing. Further, when the amount of the heterogeneous component is large, the easiness of polishing differs between the sialon and the heterogeneous component, and the surface flatness is not sufficiently high. In particular, when the out-of-phase component is difficult to polish, the out-of-phase portion tends to remain as a convex portion, which makes it difficult to bond to the functional substrate. Examples of the heterogeneous component include Al ₂ O ₃ , Si ₂ ON ₂ , Si ₃ Al ₆ O ₁₂ N ₂ , and mullite.

According to the Sialon sintered body of the present embodiment, the number of pores existing on the polished surface can be reduced. The number of pores having a maximum length of 0.5 μm or more and a depth of 0.08 μm or more, which exists per 100 μm × 100 μm area of the polished surface, is preferably 10 or less, more preferably 5 or less, and 3 or less. Is more preferable.

Regarding the surface flatness of the Sialon sintered body of the present embodiment, for example, the centerline average roughness Ra in the measurement range of 100 μm × 140 μm on the mirror-polished surface is 1.0 nm or less, and the same. It is preferable that the difference Pt between the maximum peak height and the maximum valley depth in the measurement range satisfies at least one of 30 nm or less. Ra is more preferably 0.8 nm or less. Pt is more preferably 25 nm or less.

The Young's modulus of the Sialon sintered body of the present embodiment is preferably 180 GPa or more, more preferably 200 GPa or more, still more preferably 220 GPa or more.

In the Sialon sintered body of the present embodiment, the value of z is preferably 0.5 ≦ z ≦ 4.0. Within this range, the number of pores described above can be further reduced. The value of z is more preferably 0.5 ≦ z ≦ 3.2. Within this range, the number of pores described above can be further reduced.

Next, an embodiment of a method for manufacturing a Sialon sintered body will be described. The production flow of the sialon sintered body includes a step of producing a sialon raw material powder and a step of producing a sialon sintered body.

(Preparation of Sialon raw material powder)
As the raw material powder, commercially available silicon nitride, aluminum nitride, alumina and silica powder having an impurity metal element content of 0.2% by mass or less and an average particle size of 2 μm or less were used. Using these raw materials, the composition is selected so that Si: Al: O: N = (6-z): z: z: (8-z) (however, 0 <z≤4.2) and the mass ratio is selected. Is determined and each component is mixed to prepare a raw material powder. The value of z is preferably 0.5 ≦ z ≦ 4.0, more preferably 0.5 ≦ z ≦ 3.2. Each powder is preferably fine in order to be finely sintered, and preferably has an average particle size of 0.5 to 1.5 μm. In addition, a precursor substance that produces these components by heating may be used as a raw material for each component. Each powder is mixed and dispersed in a solvent to prepare a slurry having a sialon composition. The mixing method is not particularly limited, and for example, a ball mill, an attritor, a bead mill, a jet mill, or the like can be used. However, at this time, it is necessary to pay sufficient attention to the components mixed from the media and their amounts. That is, it is preferable to use a boulder or pot made of alumina or silicon nitride, which does not become an impurity even if mixed, as the medium. Further, resin pots and boulders can also be used because they can be removed in a firing step or the like. Metallic media is not preferable because it has a large amount of impurities. The obtained slurry is dried, and the dried product is passed through a sieve to obtain a sialon raw material powder. If the composition deviates due to the mixing of media components or the like during pulverization, the composition may be appropriately adjusted to obtain a raw material powder. Alternatively, the pulverized product may be used as the sialon raw material powder as it is by adjusting the mass of each component of the mixed powder in advance so that the mass of each component contained in the pulverized product has a desired sialon composition.

(Preparation of Sialon sintered body)
The obtained Sialon raw material powder is molded into a predetermined shape. The molding method is not particularly limited, and a general molding method can be used. For example, the above-mentioned Sialon raw material powder may be press-molded as it is by a mold. In the case of press molding, if the Sialon raw material powder is made into granules by spray drying, the moldability is improved. In addition, an organic binder can be added to prepare clay and extrude it, or a slurry can be prepared and sheet-molded. In these processes, it is necessary to remove the organic binder component before or during the firing step. Further, high pressure molding may be performed by CIP (cold hydrostatic pressure press).

Next, the obtained molded product is fired to produce a Sialon sintered body. At this time, it is important to keep the sintered particles fine and to discharge pores during sintering in order to improve the surface flatness of the Sialon sintered body. The hot press method is very effective as the method. By using the hot press method, densification progresses in the state of fine particles at a low temperature as compared with normal pressure sintering, and it is possible to suppress the residual coarse pores often seen in normal pressure sintering. The firing temperature during hot pressing is preferably 1725 to 1900 ° C, and more preferably 1750 to 1900 ° C in order to minimize the number of different phases. The press pressure during hot pressing is preferably 100 to 300 kgf / cm ² , more preferably 150 to 250 kgf / cm ² . The holding time at the firing temperature (maximum temperature) can be appropriately selected in consideration of the shape and size of the molded product, the characteristics of the heating furnace, and the like. The specific preferred holding time is, for example, 1 to 12 hours, more preferably 2 to 8 hours. The firing atmosphere during hot pressing is preferably a nitrogen atmosphere in order to avoid decomposition of sialon.

Next, an embodiment of the composite substrate will be described. The composite substrate is a bonding of a functional substrate and the above-mentioned support substrate made of a Sialon sintered body. The ratio of the area actually joined (joined area ratio) in the joined interface is preferably 80% or more, and more preferably 90% or more. When the bonding area ratio is large as described above, the functional substrate and the support substrate show good bonding properties. The functional substrate is not particularly limited, and examples thereof include lithium tantalate, lithium niobate, gallium nitride, and silicon. The joining method may be direct joining or may be joined via an adhesive layer, but direct joining is preferable. In the case of direct bonding, after activating the respective bonding surfaces of the functional substrate and the support substrate, both substrates are pressed with the two bonding surfaces facing each other. The junction surface is activated, for example, by irradiating the junction surface with a neutral atomic beam of an inert gas (argon or the like), or by irradiating the junction surface with a plasma or an ion beam. On the other hand, when joining via an adhesive layer, for example, an epoxy resin or an acrylic resin is used as the adhesive layer. The ratio of the thickness of the functional substrate to the support substrate (thickness of the functional substrate / thickness of the support substrate) is preferably 0.1 or less. FIG. 1 shows an example of a composite substrate. The composite substrate 10 is formed by directly joining the piezoelectric substrate 12, which is a functional substrate, and the support substrate 14.

Next, an embodiment of the electronic device will be described. The electronic device utilizes the composite substrate described above. Examples of such electronic devices include elastic wave devices (elastic surface wave devices, Lamb wave elements, thin film resonators (FBAR), etc.), LED devices, optical waveguide devices, switch devices, and the like. When the above-mentioned composite substrate is used for the elastic wave device, the coefficient of thermal expansion of the Sialon sintered body, which is the support substrate, is as small as 3.0 ppm / K (40-400 ° C) or less, and the Young's modulus is low. Because it is high, the binding force of the functional substrate is increased. As a result, the frequency temperature dependence of the device is greatly improved. FIG. 2 shows an example of an electronic device 30 manufactured by using the composite substrate 10. The electronic device 30 is a 1-port SAW resonator, that is, a surface acoustic wave device. First, a pattern of a large number of electronic devices 30 is formed on the piezoelectric substrate 12 of the composite substrate 10 by using a general photolithography technique, and then the patterns are cut into each electronic device 30 by dicing. The electronic device 30 has IDT (Interdigital Transducer) electrodes 32 and 34 and reflection electrodes 36 formed on the surface of the piezoelectric substrate 12 by photolithography technology.

Hereinafter, examples of the present invention will be described. The following examples do not limit the present invention in any way.

1. 1. Preparation of raw material powder The raw material powder includes commercially available silicon nitride powder (oxygen content 1.3% by mass, impurity metal element content 0.2% by mass or less, average particle size 0.6 μm) and aluminum nitride (oxygen content). 0.8% by mass, impurity metal element content 0.1% by mass or less, average particle size 1.1 μm), alumina (purity 99.9% by mass, average particle size 0.5 μm), silica (purity 99.9 mass) %, Average particle size 0.5 μm) powder was used.

The sialon raw material powders A to G and J were prepared as follows. That is, first, each powder of silicon nitride, aluminum nitride, alumina, and silica is weighed so as to have a sialon composition (Si _6-z Al _z O _z N _8-z ) having a value of z shown in Table 1. Alumina was made into a ball stone (φ5 mm) and mixed with isopropyl alcohol as a solvent in a ball mill for 4 hours to prepare a slurry of mixed powder. The obtained slurry was dried at 110 ° C. under a nitrogen gas flow, and the dried product was passed through a sieve to obtain Sialon raw material powders A to G and J. The sialone raw material powder preferably has a small excess oxygen amount in order to suppress the heterogeneous component, and the sialon raw material powders A to G have an excess oxygen amount of 1.0% by mass or less. On the other hand, the excess oxygen content of the Sialon raw material powder J was 2.7% by mass.

As the silicon nitride raw material powder H, the above-mentioned silicon nitride powder was used alone. As the silicon nitride raw material powder I, each powder of silicon nitride, Itria (purity 99.9% by mass or more, average particle size 1.1 μm) and magnesia (purity 99.9% by mass, average particle size 1.8 μm) is shown in Table 1. Weighed so as to have the composition shown in (1), a dried product was prepared in the same manner as the Sialon raw material powders A to G and J, and the dried product was passed through a sieve.

2. 2. Fabrication and evaluation of sintered body (1) Experimental example 1
The Sialon sintered body of Experimental Example 1 was formed by molding the Sialon raw material powder A into a diameter of 125 mm and a thickness of about 20 mm using a mold, and then using a graphite mold at a press pressure of 200 kgf / cm ² and a maximum temperature of 1800 ° C. 4 It is hot-press fired for hours. The firing atmosphere was a nitrogen atmosphere. The obtained sintered body had a diameter of 125 mm and a thickness of about 8 mm. A 4 mm × 3 mm × 40 mm size anti-folding rod or the like was cut out from this sintered body, and various characteristics were evaluated. The evaluation methods for various characteristics are shown below. The results are shown in Table 2. The properties of the surface of the sintered body were evaluated by polishing one surface of a test piece having a size of about 4 mm × 3 mm × 10 mm into a mirror surface. The polishing was performed by lapping polishing 3 μm diamond abrasive grains and finally 0.5 μm diamond abrasive grains.

・ Bulk density and open porosity Measured by the Archimedes method using distilled water.

-Relative density Relative density was calculated as bulk density ÷ apparent density.

-Crystal phase and peak intensity ratio Ix
The sialon sintered body was pulverized, and the sialon and the different phase were identified and the maximum peak intensity of each phase was calculated by an X-ray diffractometer. In identifying the heterogeneous phase, it is necessary to pay sufficient attention to the mixed phase from the media such as the mortar and pestle and the amount thereof when the sintered body is crushed. A fully automatic multipurpose X-ray analyzer D8 ADVANCE was used as the XRD apparatus, and the measurement conditions were CuKα, 40 kV, 40 mA, and 2θ = 10-70 °. From the X-ray diffraction pattern, the intensity of the maximum peak of each detected different phase (P, Q, R, ...) With respect to the intensity (Ic) of the maximum peak of Sialon (2θ = 32.8 to 33.5 °). The ratio of the sum of (Ip, Iq, Ir, ...) (Peak intensity ratio Ix) was calculated from the following formula. When the maximum peak overlaps with other peaks, the peak with the second highest peak intensity was adopted instead of the maximum peak.
Ix = (Ip + Iq + Ir ...) / Ic

-Average grain size of Sialon sintered grains Observe the Sialon sintered grains in the fracture surface in a field of 127 μm × 88 μm with SEM, determine the grain size of 10 or more Sialon sintered grains in the field, and calculate the average value. The average particle size of the Sialon sintered grains was used. The particle size of one Sialon sintered grain was taken as the average value of the major axis and the minor axis of the sintered grain.

・ Number of pores Observe the mirror-finished surface as described above with a 3D measurement laser microscope, and count four values per unit area of pores with a maximum length of 0.5 μm or more and a depth of 0.08 μm or more. The average value was taken as the number of pores. The unit area was 100 μm square.

・ Surface flatness Measure the average roughness Ra of the center line and the difference Pt between the maximum peak height and the maximum valley depth using a three-dimensional optical profiler (Zygo) for the mirror-finished surface as described above. did. Ra and Pt in the present specification correspond to the arithmetic mean roughness Ra of the cross-section curve and the maximum cross-section height Pt of the cross-section curve as defined in JIS B 0601: 2013. The above Ra and Pt were used as surface flatness. The measurement range was 100 μm × 140 μm.

-Young's modulus was measured by the static deflection method according to JIS R1602. The shape of the test piece was a 3 mm × 4 mm × 40 mm anti-folding rod.

・ Coefficient of thermal expansion (40-400 ° C)
According to JIS R1618, the measurement was performed by the push rod difference method. The shape of the test piece was 3 mm × 4 mm × 20 mm.

As shown in Table 2, the Sialon sintered body of Experimental Example 1 had excellent properties. Specifically, the bulk density of the Sialon sintered body of Experimental Example 1 was 3.16 g / cm ³ , the open porosity was 0.00%, and the relative density was 100 %. In the crystal phase, in addition to sialon, a small amount of alumina and silicon nitride were detected. The ratio (peak intensity ratio) Ix of the sum of the maximum peak intensities of each component other than sialon to the maximum peak intensity of sialon was 0.0012, which was extremely small. In the range of 100 μm × 100 μm of the polished surface, the number of pores having a maximum length of 0.5 μm or more was very small, one. Regarding the surface flatness of the polished surface, it was found that the average roughness Ra of the center line was as small as 0.4 nm, and the height difference Pt between the maximum peak height and the maximum valley depth was as small as 15 nm.

(2) Experimental Examples 2 to 6
The Sialon sintered bodies of Experimental Examples 2 to 6 were hot-press fired in the same manner as in Experimental Example 1 using the Sialon raw material powders B, D to G shown in Table 1 instead of the Sialon raw material powder A. Table 2 shows the characteristics of each Sialon sintered body. All Sialon sintered bodies have excellent porosity of 0.1% or less, relative density of 99.9% or more, number of pores of 10 or less, and peak intensity ratio Ix of 0.005 or less. I was prepared.

(3) Experimental example 7
The Sialon sintered body of Experimental Example 7 was hot-press sintered using Sialon raw material powder C in the same manner as in Experimental Example 1. The sialon raw material powder C is consistent in that the z value is 1.0 as compared with the sialon raw material powder B used in Experimental Example 2, but there are three starting materials, Si ₃ N ₄ , Al N and Al ₂ O ₃ . It is different from Sialon raw material powder B which uses three of Si ₃ N ₄ , Al N and SiO ₂ in that it uses. Since the Sialon sintered body of Experimental Example 7 had the same excellent characteristics as the Sialon sintered body of Experimental Example 2, the starting materials were among Si ₃ N ₄ , Al N, Al ₂ O ₃ and SiO ₂ . It was found from the above that it should be appropriately selected so as to obtain the desired sialon.

(4) Experimental Examples 8 to 12
Experimental Examples 8 to 11 are examples in which the maximum temperature during firing of Experimental Examples 1, 2, 4, and 5 is changed to 1750 ° C., and Experimental Example 12 is an example in which the maximum temperature during firing of Experimental Example 3 is changed to 1725 ° C. This is an example. As shown in Table 2, it was found that the Sialon sintered bodies of Experimental Examples 8 to 12 had excellent properties similar to those of the Sialon sintered bodies of Experimental Examples 1 to 5.

The Sialon sintered bodies of Experimental Examples 1 to 12 have an excess oxygen content of 1.0% by mass or less.

(5) Experimental Examples 13 to 16
Experimental Examples 13 to 16 are examples in which the maximum temperature at the time of firing in Experimental Examples 1 to 3 and 5 is changed to 1700 ° C. Since the firing temperature of the Sialon sintered bodies of Experimental Examples 13 to 15 was too low, the open porosity exceeded 0.1, the relative density was 99.9% or less, the densification was insufficient, and the number of pores was large. There were 33 or 50 or more. The Sialon sintered body of Experimental Example 16 had a porosity of 0.01%, a relative density of 99.97%, and a number of pores of 2, but had a high peak intensity ratio Ix of 0.0221 and a center line. The values of the average roughness Ra and the maximum cross-sectional height Pt deteriorated. It is considered that the reason why the peak intensity ratio Ix is high is that the firing temperature is too low, the reaction (sialonization) of the raw material components becomes insufficient, and more alumina, which is one of the intermediate products, is precipitated as a heterogeneous phase. In addition, the reason why the average roughness Ra of the center line and the difference in height between the maximum peak height and the maximum valley depth Pt deteriorated is that the alumina deposited as a different phase and the sialon are easily polished, so that the alumina is convex. It is thought that it was because it remained as.

(6) Experimental Examples 17, 18
In Experimental Example 17, hot press firing was carried out in the same manner as in Experimental Example 1 except that silicon nitride raw material powder H (z = 0) was used as a starting material. The obtained fired body had an open porosity of 52.1% and a relative density of 47.95%, and was not sintered. In Experimental Example 18, hot press firing was carried out in the same manner as in Experimental Example 1 except that silicon nitride raw material powder I (z = 0, addition of sintering aids Y ₂ O ₃ and Mg O) was used as a starting material. .. The obtained sintered body consisted of a structure in which columnarized crystals peculiar to silicon nitride were developed, and pores were observed at the grain boundaries. Therefore, in the range of 100 μm square of the polished surface, the number of pores having a maximum length of 0.5 μm or more was 50 or more, and the number of pores could not be reduced.

(7) Experimental Example 19
The Sialon sintered body of Experimental Example 19 was hot-press fired using Sialon raw material powder J in the same manner as in Experimental Example 8. The obtained fired body had a relative density of 99.98% and had three pores, and was sufficiently densified. However, the peak intensity ratio Ix was as high as 0.0492, and the values of the centerline average roughness Ra and the maximum cross-sectional height Pt were poor due to the precipitation of many heterogeneous phases, and sufficient flatness could not be obtained. The Sialon sintered body of Experimental Example 19 has an excess oxygen amount of 2.7% by mass, and corresponds to Example 1 of JP-A-62-121268.

Of the above-mentioned Experimental Examples 1 to 19, Experimental Examples 1 to 12 correspond to Examples of the present invention, and Experimental Examples 13 to 19 correspond to Comparative Examples.

3. 3. Bondability An attempt was made to join an LT substrate having a diameter of 100 mm and a thickness of 250 μm to a support substrate having a diameter of 100 mm and a thickness of 230 μm cut out from the sintered body of Experimental Examples 2, 4 and 14. In the surface activation treatment before joining, both substrates were irradiated with a neutral atomic beam of argon using a FAB gun. Then, after bonding both substrates, they were pressed for 1 minute with a bonding load of 0.1 ton, and the support substrate and the LT substrate were directly bonded at room temperature. In the composite substrate obtained from the sintered bodies of Experimental Examples 2 and 4, almost no bubbles were observed at the bonding interface, and the ratio of the actually bonded area (bonding area ratio) to the bonding interface was 90% or more. Yes, it was well joined. On the other hand, in the composite substrate obtained from the sintered body of Experimental Example 14, bubbles were observed at the bonding interface, and the ratio of the actually bonded area (bonding area ratio) to the bonding interface was 80% or less. Met. Here, the bonding area is the area of the portion without bubbles, and the bonding area ratio is the ratio of the bonding area to the area of the entire bonding interface. Although the FAB gun is used here, an ion gun may be used instead.

This application is based on the international application PCT / JP2016 / 77627 filed on September 20, 2016, which is incorporated herein by reference in its entirety.

The present invention can be used for electronic devices such as lamb wave elements and thin film resonators (FBARs) in addition to surface acoustic wave elements.

10 composite substrate, 12 piezoelectric substrate, 14 support substrate, 30 electronic device, 32, 34 IDT electrode, 36 reflective electrode.

Claims (8)

It is represented by Si _6-z Al _z O _z N _8-z (0 <z ≦ 4.2), the open porosity is 0.1% or less, the relative density is 99.9% or more, and the X-ray diffraction pattern is shown. The ratio of the sum of the maximum peak intensities of each component other than sialon to the maximum peak intensity of sialon is 0.005 or less.
Sialon sintered body. The surface of the Sialon sintered body has a centerline average roughness (Ra) of 1.0 nm or less in a measurement range of 100 μm × 140 μm.
The Sialon sintered body according to claim 1. The surface of the Sialon sintered body has a height difference (Pt) of 30 nm or less between the maximum peak height and the maximum valley depth in a measurement range of 100 μm × 140 μm.
The Sialon sintered body according to claim 1 or 2. The Young's modulus of the Sialon sintered body is 180 GPa or more.
The sialon sintered body according to any one of claims 1 to 3. The method for producing a sialon sintered body according to any one of claims 1 to 4.
Among the components of silicon nitride, aluminum nitride, alumina and silica having a purity of 99.8% by mass or more, Si: Al: O: N = (6-z): z: z: (8-z) ( However, the components are selected so that 0 <z ≦ 4.2), the mass ratio is determined, and the components are mixed to prepare a raw material powder. The raw material powder is formed into a predetermined shape, and then the firing temperature is 1725. A sialon sintered body is obtained by hot press firing at ~ 1900 ° C. and a press pressure of 100 to 300 kgf / cm ² .
Manufacturing method of Sialon sintered body. A composite board in which a support board and a functional board are joined together.
The support substrate is the sialon sintered body according to any one of claims 1 to 4.
Composite board. The joint is a direct joint,
The composite substrate according to claim 6. An electronic device using the composite substrate according to claim 6 or 7.

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