Metal-ceramic composite

Abstract

To provide a metallized silicon nitride-containing ceramic substrate whose exposed surface allows formation of a bond of high adhesive strength with a casting compound.SOLUTION: A metal-ceramic composite comprises: a ceramic substrate comprising a front side and a rear side and containing β-silicon nitride; and a metal coating on the front side of the ceramic substrate. The metal coating comprises at least one recess, and a surface of the ceramic substrate is exposed by the recess. At least in the region of the recess, the ceramic substrate satisfies the specific condition: SO-βSN / SB-βSN≥0.8. When the formula is satisfied, the adhesive strength of a casting compound onto the ceramic substrate can be improved.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a metal-ceramic composite that can be used as a ceramic circuit carrier in power electronics.

[0002] In power electronics, printed circuit boards should be designed for high currents as carriers for power components such as MOSFETs, and should be able to quickly dissipate waste heat.

[0003] Ceramic materials such as aluminum oxide, aluminum nitride, and silicon nitride have much higher thermal conductivity than the polymers used to manufacture conventional printed circuit boards, and therefore ceramic circuit carriers are often used in power modules.

[0004] Silicon nitride-based ceramic substrates possess extremely high mechanical strength and high thermal conductivity, making them highly suitable for applications in power electronics.

[0005] Silicon nitride can exist in a crystalline structure known as the "α phase" or the "β phase." These two phases have different X-ray diffraction patterns. The β phase (hereinafter also called β-silicon nitride) is the stable phase under normal sintering conditions. Therefore, β-silicon nitride is usually present in silicon nitride-based ceramic substrates.

[0006] β-silicon nitride contains needle-shaped crystallites (acine microcrystals). It is known that the mechanical properties or thermal conductivity of ceramics can be influenced by the alignment of these needle-shaped β-silicon nitride crystallites in the ceramic body. For example, if the majority of the needle-shaped crystallites are oriented along a longitudinal axis substantially parallel to the ceramic surface, this may be advantageous for the mechanical strength of the ceramic, while if the majority of the needle-shaped crystallites are aligned along a longitudinal axis substantially perpendicular to the ceramic surface, this may be more advantageous for thermal conductivity.

[0007] "Si3N4 Substrates with Anisotropic Thermal Conductivity Suitable for Power Module Applications" by T. Okuno et al., PCIM Europe digital days 2021; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Online, 2021, pp. 1-5 describes ceramic substrates each containing β-silicon nitride, where the alignment of the elongated β-silicon nitride crystallites is different. As the number of crystallites aligned along the longitudinal axis parallel to the thickness direction of the ceramic substrate (i.e., perpendicular to the front or back surface) increases, the intensity of the (101) reflection of β-silicon nitride in the X-ray diffraction pattern also increases.

[0008] Silicon nitride-based ceramic substrates are described, for example, in the following publications: N. Chasserio et al., "Ceramic Substrates for High-Temperature Electronic Integration," Journal of Electronic Materials, Volume 38 (2009), pp. 164-174; K. Hirao et al., "High Thermal Conductivity Silicon Nitride Ceramics," Journal of the Korean Ceramic Society, Volume 49 (2012), pp. 380-384; Y. Zhou et al., "Development of high-thermal-conductivity silicon nitride ceramics," Journal of Asian Ceramic Societies, 3 (2015), pp. 221-229.

[0009] An overview of a method for manufacturing silicon nitride ceramics having different textures can be found, for example, in the following publications. "Textured silicon nitride: processing and anisotropic properties" by X. Zhu and Y. Sakka, Sci. Technol. Adv. Mater., 9, 2008, 033001.

[0010] Silicon nitride-based ceramic substrates exhibit a good balance between high mechanical strength and high thermal conductivity, can be used in electronic components, and are commercially available.

[0011] A ceramic circuit carrier has a ceramic substrate, and metal layers are provided on at least one surface thereof, usually on both surfaces. In the final module, semiconductor components are applied to one of these metal layers, and the metal layer on the opposite side of the ceramic substrate is thermally conductively connected to a heat sink. The ceramic substrate electrically insulates the metal layers from each other.

[0012] A metallized ceramic substrate that functions as a ceramic circuit board, known to those skilled in the art, is manufactured, for example, by bringing the front and back surfaces of a ceramic substrate into contact with a metal film (e.g., a copper or aluminum film) and joining them together. The material joining of the metal foil is achieved, for example, by eutectic bonding or an active metal brazing method (AMB). When the metal film is a copper film, eutectic bonding is also called the DCB method or the DBC method (DCB: "direct copper bonding", DBC: "direct bonded copper"). In the case of an aluminum film, the term "DAB" ("direct aluminum bonding") is also used for eutectic bonding. A metallized ceramic substrate manufactured using the DCB process or the AMB process may also be called a DCB substrate (or a DBC substrate) or an AMB substrate.

[0013] The metallization of a silicon nitride substrate is usually performed by an active metal brazing method.

[0014] Active metal brazing materials contain, in addition to major components such as Cu, Ag, or Au, one or more elements that can react with ceramics to form an adhesion-promoting reaction layer (see, for example, Chapter 8.2.4.3 ("Active metal brazing"), pages 203-204 of Brevier Technische Keramik, Verband der Keramischen Industrie eV, 2003, Fahner Verlag). Reactive elements such as hafnium (Hf), titanium (Ti), zirconium (Zr), niobium (Nb), cerium (Ce), tantalum (Ta), and vanadium (V) are used. In the metallization of silicon nitride substrates by the active metal brazing method, the reaction layer includes, for example, nitrides, oxynitrides, and / or silicides of reactive elements (A. Ponicke et al., "Active metal brazing of copper with aluminum nitride and silicon nitride ceramics", Keramische Zeitschrift, 63(5), 2011, 334-342).

[0015] The metal layer supporting the semiconductor component is structured (for example, by etching). Structuring of the AMB substrate can be performed, for example, in a two-step process: in the first step, the metal layer is first removed in defined areas (for example, using a first etching solution); and then, in the second step, the adhesion-promoting layer obtained from the activated metal brazing process is removed (for example, using a second etching solution). By removing the metal layer in the defined areas, the ceramic substrate is exposed again in those areas.

[0016] Modules based on ceramic circuit carriers used in power electronics can be encapsulated as part of the packaging process, for example, by embedding the power module in a casting compound.

[0017] For example, embedding it in a casting compound increases its electrical dielectric breakdown strength. Furthermore, the semiconductor components and metal conductor tracks are protected from moisture and mechanically stabilized.

[0018] In areas exposed by structuring, the ceramic substrate is in direct contact with the casting compound. Significant temperature fluctuations can occur when the power module is operating. Since ceramic materials and casting compounds typically have significantly different coefficients of thermal expansion, these temperature fluctuations create mechanical stress at the interface between the ceramic and the casting compound. This can result in the casting compound delaminating from the ceramic substrate, at least partially, and forming cavities. Moisture entering these cavities can damage the power module. Furthermore, the electrical dielectric strength may be significantly reduced, at least locally.

[0019] As already mentioned above, silicon nitride-based ceramic substrates are used as circuit carriers in power electronics due to their extremely high mechanical strength and high thermal conductivity. To maximize their potential as circuit carriers, it is desirable to have high adhesive strength between the casting compound and the silicon nitride surface after embedding in the casting compound.

[0020] The object of the present invention is to provide a metallized silicon nitride-containing ceramic substrate, the exposed surface thereof enabling the formation of a bond with high adhesive strength to a casting compound.

[0021] The purpose is a metal-ceramic composite, A ceramic substrate comprising a front and rear surface and containing β-silicon nitride, A metal coating on the front surface of a ceramic substrate, The metal coating includes at least one recess, and the surface of the ceramic substrate is exposed by the recess. The ceramic substrate satisfies the following conditions, at least in the recessed region: SO-βSN / S B-βSN ≥0.8 wherein S O-βSN =I O-βSN (101) / [0.5x(I O-βSN (200)+I O-βSN (120))] S B-βSN =I B-βSN (101) / [0.5x(I B-βSN (200)+I B-βSN (120))] I O-βSN (101), I O-βSN (200) and I O-βSN (120) are the relative peak heights of the (101), (200) and (120) reflections of β-silicon nitride in the X-ray diffraction pattern measured under 3° glancing incidence using Cu-Kα radiation, and the relative peak heights are normalized with respect to the peak height of the (200) reflection. I B-βSN (101), I B-βSN (200) and I B-βSN (120) are the relative peak heights of the (101), (200) and (120) reflections of β-silicon nitride in the X-ray diffraction pattern measured by Bragg-Brentano geometry and Cu-Kα radiation, and the relative peak heights are normalized with respect to the peak height of the (120) reflection, achieved by the metal-ceramic composite.

[0022] As described above, the intensity of the (101) reflection of β-silicon nitride in the X-ray diffraction pattern is affected by the alignment of the elongated β-silicon nitride crystallites. As the number of crystallites aligned along the longitudinal axis parallel to the thickness direction of the ceramic substrate (i.e., perpendicular to the front or back surface) increases, the intensity of the (101) reflection of β-silicon nitride in the X-ray diffraction pattern, as well as the intensity ratios of the (101) reflection to the (200) and (120) reflections, also increase. The peak height in the X-ray diffraction pattern normalized with respect to the height of the reference peak can be regarded as a measure of the reflection intensity.

[0023] Grazing incidence X-ray diffraction is used to investigate the structure of regions near the surface of a sample, while X-ray diffraction in Bragg-Brentano geometry provides structural information averaged over the entire irradiation volume of the sample.

[0024] Surprisingly, within the scope of the present invention, the ratio defined above (i.e., S) O-βSN / S B-βSN It was found that the adhesive strength of the casting compound on the ceramic substrate can be improved when the condition (≥0.8) is satisfied.

[0025] For example, consider the following case: S O-βSN / S B-βSN ≥0.95

[0026] In one exemplary embodiment, the following relationship is satisfied: 2.2≧S O-βSN / S B-βSN ≥0.8

[0027] In another exemplary embodiment, the following relationship is satisfied: 2.2≧S O-βSN / S B-βSN ≥0.95

[0028] In another exemplary embodiment, the following relationship is satisfied: 1.75≧S O-βSN / S B-βSN ≥0.95

[0029] As will be explained in more detail below, the ratio according to the present invention (i.e., S O-βSN / S B-βSN The ratio (≥0.8) can be adjusted in a ceramic substrate by irradiating it with a pulsed laser beam, particularly an ultrashort pulse laser. This treatment appears to cause a relative increase in elongated β-silicon nitride crystallites oriented along a longitudinal axis substantially parallel to the thickness direction of the ceramic substrate (i.e., perpendicular to the front or back surface) in the region near the surface of the ceramic substrate. This is because S O-βSN The value (i.e., I O-βSN(101) / [0.5x(I O-βSN (200)+I O-βSN (120))]) S B-βSN The value of I B-βSN (101) / [0.5x(I B-βSN (200)+I B-βSN (120))) showed a larger increase than, therefore, ratio S O-βSN / S B-βSN This means that it will increase.

[0030] In one exemplary embodiment, the ceramic substrate satisfies the following conditions, at least in the recessed region. 0.4≦S O-βSN ≤2.0 In the formula, S O-βSN The above meanings are different.

[0031] In another exemplary embodiment, the following conditions are met: 0.6≦S O-βSN ≤1.3

[0032] The indexing of X-ray diffraction reflections in the X-ray diffraction pattern and diffractogram of β-silicon nitride is known to those skilled in the art. For example, using Cu-Kα rays, the (101) reflection appears at a diffraction angle (2θ) of 33.7 ± 1.0°, the (200) reflection appears at a diffraction angle (2θ) of 27.1 ± 1.0°, and the (120) reflection appears at a diffraction angle (2θ) of 36.1 ± 1.0°.

[0033] Optionally, the ceramic substrate may contain one or more metal oxides, which were added, for example, as sintering aids during the manufacture of the ceramic substrate. For example, the ceramic substrate may contain one or more of the following oxides: one or more alkaline earth metal oxides such as magnesium oxide, one or more transition metal oxides (e.g., one or more rare earth oxides such as yttrium oxide or erbium oxide), silicon oxide (e.g., SiO2), or silicates.

[0034] The ceramic substrate has a thickness ranging from, for example, 0.1 mm to 1.0 mm.

[0035] On the front surface of the ceramic substrate, there is a metal coating containing at least one recess, such that the surface of the ceramic substrate is exposed by the recess. This metal coating is also called a structured metal coating. Semiconductor components can be mounted on the structured metal coating.

[0036] Optionally, the metal coating can also be applied to the rear surface of the ceramic substrate. This rear metal coating may also optionally include at least one recess through which the surface of the ceramic substrate is exposed. To achieve the most efficient heat dissipation possible, it may be preferable that the rear metal coating does not include such recesses.

[0037] The metal coating present on the front and optionally rear surfaces of the ceramic substrate is, for example, a copper coating or an aluminum coating. The metal coating has a thickness in the range of, for example, 0.05 mm to 1.5 mm, more preferably 0.2 mm to 0.8 mm.

[0038] If the metal coating is a copper coating, for example, it has a copper content of at least 97% by weight.

[0039] If the metal coating is an aluminum coating, for example, it has an aluminum content of at least 97% by weight.

[0040] The metal coating can be applied to the front and optionally rear surfaces of the ceramic substrate using methods known to those skilled in the art.

[0041] For example, a metal foil (e.g., copper foil or aluminum foil) is bonded to the front surface of a ceramic substrate by activated metal brazing.

[0042] In activated metal brazing, for example, a bond is made between a metal foil and a ceramic substrate using an activated metal brazing material at a temperature of approximately 600 to 1,000°C. Depending on their alloy composition, the activated metal brazing material can wet non-metallic inorganic materials such as ceramic substrates. In addition to main components such as copper, silver, and / or gold, the activated metal brazing material also contains one or more activated metals such as Hf, Ti, Zr, Nb, V, Ta, or Ce, which can react with the bonding partner (e.g., the ceramic substrate).

[0043] Preferably, a reaction layer obtained by an activated metal brazing method is present between the metal coating and the front surface of the ceramic substrate. The reaction layer is, for example, one or more elements selected from Hf, Ti, Zr, Nb, V, Ta, and Ce, preferably selected from Hf, Ti, Zr, Nb, and Ce, more preferably selected from Hf, Ti, and Zr. RS Includes. Particularly preferred element E in the reaction layer. RS It is titanium. For example, element E RS It is present in the reaction layer in the form of nitrides, oxynitrides, and / or silicides. For example, the reaction layer contains element E RS It contains at least 50% by weight in total. For example, the reaction layer contains at least 70% by weight, more preferably at least 85% by weight, of nitrides, oxynitrides, and silicides of element ESR. In power electronics semiconductor modules, silver migration can cause problems. Therefore, it may be preferable for the reaction layer to contain silver in a proportion of 5% by weight or less, more preferably 1% by weight or less, or even to contain no silver at all.

[0044] The surface of the ceramic substrate is exposed in several steps, for example. First, the metal coating is removed, for example, by etching, to expose the reaction layer formed during the activated metal brazing process. Next, the exposed reaction layer is removed, for example, by etching or laser ablation. Preferably, the exposed reaction layer is removed using an ultrashort pulse laser (e.g., an IR picosecond or femtosecond laser).

[0045] To electrically insulate the regions of the metal coating separated from each other by the recesses, it is sufficient to perform material removal with a pulsed laser beam only to the extent that the conductive material is completely removed in the treated region, while avoiding structural modification of the β-silicon nitride phase on the surface of the ceramic substrate.

[0046] However, within the scope of the present invention, processing with an ultrashort pulse laser not only exposes the surface of the ceramic substrate but also structurally modifies the β-silicon nitride phase on the surface of the ceramic substrate. For example, it has been found that when a pulsed laser beam having a pulse energy of at least 10 μJ passes over the surface of the ceramic substrate several times, it is advantageous for setting the peak height ratio according to the present invention.

[0047] Within the scope of the present invention, it is also possible to first expose the surface of the ceramic substrate by a single-step or multi-step etching process, and then treat the exposed ceramic substrate surface with an ultrashort pulse laser (e.g., an IR femtosecond or picosecond laser) until the peak height ratio according to the present invention is achieved.

[0048] However, for process efficiency reasons, it may be preferable to use a pulsed laser beam for both exposing the surface of the ceramic substrate and modifying the structure of the β-silicon nitride phase on the surface of the ceramic substrate.

[0049] The region of the recess in the ceramic substrate exhibiting the peak height ratio according to the present invention may include, for example, at least 50%, more preferably at least 70%, of the surface of the ceramic substrate exposed by the recess, or may further include substantially the entire surface of the ceramic substrate exposed by the recess.

[0050] The exposed surface of the ceramic substrate that satisfies the peak height ratio according to the present invention results in improved adhesion strength of the casting compound to the ceramic substrate. Furthermore, the metal-ceramic composite according to the present invention also possesses high mechanical strength.

[0051] The present invention is a semiconductor module, The above-mentioned metal-ceramic composite, This also relates to semiconductor modules, which include one or more semiconductor components.

[0052] Preferably, the semiconductor module also includes a casting compound, which contacts the surface of the ceramic substrate of the metal-ceramic composite that is exposed by the recesses.

[0053] Casting compounds for electronic components are known to those skilled in the art. These casting compounds contain, for example, polymers (e.g., thermoplastic polymers or thermosetting polymers). For example, the casting compounds may optionally contain cured epoxy resins or silicone resins, polyurethanes, or inorganic cements (e.g., phosphate cement).

[0054] Measurement method Determination of the peak height of diffraction reflection X-ray diffraction measurements were performed in two configurations to determine the peak height of the diffraction reflection.

[0055] The initial measurements used the so-called Bragg-Brentano geometry. The peak heights of the reflections (101), (200), and (120) were determined in the diffractograms recorded with this geometry. The peak heights were normalized relative to the peak height of the (120) reflection.

[0056] Further measurements were performed under graze incidence (3°). The peak heights of the reflections (101), (200), and (120) were also determined in the diffractograms measured under graze incidence. The peak heights were normalized relative to the peak height of the (200) reflection.

[0057] Diffraction meter: Stoe&Cie GmbH, 2-circuit X-ray powder diffractometer, type Stadi P Focusing: Using a secondary monochromator and scintillation counter, using Bragg-Brentano geometry or a grazing incidence angle (3°). X-ray tube: copper anode Wavelength: 1.54060Å Cu-Kα Operating voltage: 40kV Operating current: 30mA Measurement range: 2θ: 5° to 100° in 0.02° steps, Omega: 2.5° to 50° in 0.01 step steps GI measurement range: 2θ: 5° to 100° in 0.03° steps, Omega: 3° Time / Step: 10 seconds

[0058] The diffractometer was adjusted and calibrated using NIST standard Si(640d). A sample for XRD measurement was cut out in the form of a 20 × 20 × 0.23 mm platelet from an exposed ceramic substrate.

[0059] Composition of the adhesion-promoting layer The composition of the adhesion-promoting layer is determined by energy-dispersive X-ray spectroscopy (EDX) combined with scanning electron microscopy (SEM-EDX).

[0060] In SEM-EDX, a focused primary electron beam is guided (scanned) point by point across the sample surface. Scattered electrons are detected using a detector, and the number of electrons per pixel yields a grayscale microscopic image of the sample surface. Furthermore, the primary electron beam excites the sample to emit characteristic X-ray radiation, and the elements in the sample and their weight percentages can be determined by analyzing the energy spectrum using an EDX detector. For inspection, for example, a scanning electron microscope (JSM-6060 SEM, JEOL Ltd) equipped with a silicon drift EDX detector (NORAN, Thermo Scientific Inc.) and analysis software (Pathfinder Mountaineer EDS System, e.g., version 2.8, Thermo Scientific Inc.) are used. For scanning electron microscopy, the following settings are used: magnification: 1000x, acceleration voltage = 15kV, working distance = 10mm, spot size (50~60) (set to reach 25%+ / -5% of the EDX detector's dead time). The EDX spectrum was detected using the following settings on the EDX detector: Live time = 30 seconds, Speed ​​= Auto, Low energy cutoff = 100 keV, High energy cutoff = Auto (following the SEM acceleration voltage).

[0061] SEM-EDX allows for the qualitative and quantitative determination of the composition of the adhesion-promoting layer (by detecting specific elements and phases, such as metal nitride phases present in the adhesion-promoting layer). For example, measurements are performed at at least 10 points on the adhesion-promoting layer. [Examples]

[0062] Five silicon nitride ceramic substrates from the same product batch were used in the examples. The silicon nitride is substantially present in the β phase. O-βSN / S B-βSN The ratio was determined for each of these substrates. The starting substrate was S O-βSN / S B-βSN The ratios were substantially identical.

[0063] S of the starting substrateO-βSN / S B-βSN :0.63+ / -0.02

[0064] Four of the five silicon nitride substrates were metallized using the same activated metal brazing process under the conditions described below.

[0065] An activated metal brazing paste was applied to one side of a ceramic substrate by screen printing over an area of ​​168 mm × 130 mm and pre-dried at 125°C for 15 minutes. The activated metal brazing paste consisted of 67 wt% copper powder, 19.8 wt% tin powder, 3.7 wt% titanium hydride, and 9.5 wt% organic vehicle. The thickness of the paste after pre-drying was 25 ± 5 μm. Subsequently, a copper film made of oxygen-free, highly conductive copper with a purity of 99.99% and dimensions of 170 mm × 132 mm × 0.3 mm was placed on the pre-dried paste. Next, the resulting arrangement was flipped over, and the paste was similarly applied to the opposite side of the ceramic substrate by screen printing, pre-dried, and the copper film was attached to obtain a sandwich arrangement. The sandwich arrangement was loaded with a 1 kg weight and fired at a maximum temperature of 910°C for 20 minutes, then cooled to room temperature to obtain an unstructured metal-ceramic composite. In the manufacturing process using the activated metal brazing method, an adhesion-promoting reaction layer exists between the metal coating and the ceramic substrate. This layer contains titanium (for example, in the form of a nitride).

[0066] Each of the four metal-ceramic composites was subjected to a first structuring process using an etching solution containing CuCl2. The metal coating in the etched area on the front surface of the ceramic substrate was substantially completely removed. However, the reaction layer obtained from the activated metal brazing process was not removed with the CuCl2-containing etching solution.

[0067] In comparative example VB1, the exposed reaction layer was removed using an etching solution containing ammonium fluoride, fluoroboric acid, and hydrogen peroxide.

[0068] In Examples EB1 to EB3 of the present invention, the exposed reaction layer was removed by laser treatment using a pulsed laser beam from an IR picosecond laser. The energy of the laser pulse was at least 12.5 μJ. In Example EB1, the exposed reaction layer was scanned only once with the pulsed laser beam along a specific scan line. In Examples EB2 and EB3, the scan line was scanned twice with the laser beam, and a higher pulse energy was used in EB3 than in EB2.

[0069] Regarding the exposed ceramic surface of Examples EB1 to EB3 and Comparative Example VB1 according to the present invention, S O-βSN S B-βSN and ratio S O-βSN / S B-βSN The following measurements were taken. Subsequently, the casting compound was applied to each of the exposed ceramic surfaces, and the adhesive strength was determined.

[0070] The casting compound was also applied to an unmetallized silicon nitride starting substrate, and the adhesive strength was determined (Comparative Example VB0).

[0071] The adhesive strength was determined as follows: To determine the adhesion of the casting compound (silicone), two plates (plate size: 20 × 20 × 0.32 mm) were cut from the respective exposed areas of the ceramic substrate. Then, the two plates taken from the same ceramic substrate were joined using Sylgard 527 silicone to form a test specimen. Since the overlap of both plates was 1 cm, the adhesive surface area was always 2 cm. 2 The silicone was cured in air at 125°C for 2 hours. Each test specimen was compressed with a load of 50g to create a uniformly thin silicone layer.

[0072] The specimens produced in this manner were tested for shear strength (testing machine: Model Zwicki 500, ZwickRoell GmbH & Co. KG). The maximum shear force was determined in each case.

[0073] The results are summarized in Table 1 below.

[0074] [Table 1]

[0075] Treatment of the silicon nitride surface using a pulsed laser caused structural modification of the β-silicon nitride phase on the surface of the ceramic substrate, as evidenced by the change in the intensity ratio of (101) reflections to (200) and (120) reflections.

[0076] This process appears to cause a relative increase in elongated β-silicon nitride crystallites oriented along a longitudinal axis substantially parallel to the thickness direction of the ceramic substrate (i.e., perpendicular to the front or back surface) in the region near the surface of the ceramic substrate. O-βSN The value of S B-βSN It shows a larger increase than the value of S, therefore, O-βSN / S B-βSN This means the ratio is increasing.

[0077] The conditions according to the present invention, namely, S O-βSN / S B-βSN Silicon nitride ceramics satisfying ≥0.8 exhibit remarkably good adhesive strength to the applied casting compound.

Claims

1. A metal-ceramic composite, A ceramic substrate comprising a front and rear surface and containing β-silicon nitride, The ceramic substrate includes a metal coating on the front surface, The metal coating includes at least one recess, and the surface of the ceramic substrate is exposed by the recess. The ceramic substrate satisfies the following conditions in at least the region of the recess: S Ｏ－βＳＮ / S Ｂ－βＳＮ ≧0.8 During the ceremony, S Ｏ－βＳＮ =I Ｏ－βＳＮ (101) / [0.5x(I Ｏ－βＳＮ (200)+I Ｏ－βＳＮ (120))] S Ｂ－βＳＮ =I Ｂ－βＳＮ (101) / [0.5x(I Ｂ－βＳＮ (200)+I Ｂ－βＳＮ (120))] I Ｏ－βＳＮ (101), I Ｏ－βＳＮ (200) and I Ｏ－βＳＮ (120) is the relative peak height of the (101), (200), and (120) reflections of the β-silicon nitride in the X-ray diffraction pattern measured under a 3° grazing incidence using Cu-Kα rays, and the relative peak height is normalized with respect to the peak height of the (200) reflection. I Ｂ－βＳＮ (101), I Ｂ－βＳＮ (200) and I Ｂ－βＳＮ (120) is the relative peak height of the (101), (200), and (120) reflections of the β-silicon nitride in the Bragg-Brentano geometry and the X-ray diffraction pattern measured with Cu-Kα rays, where the relative peak heights are normalized relative to the peak height of the (120) reflection, in a metal-ceramic composite.

2. 2.2 ≥ S Ｏ－βＳＮ / S Ｂ－βＳＮ The metal-ceramic composite according to claim 1, wherein the ratio is ≥ 0.

8.

3. The following conditions are met: 0.4≦S Ｏ－βＳＮ ≦2.0 In the formula, S Ｏ－βＳＮ The metal-ceramic composite according to claim 1, wherein is defined as having the meaning described in claim 1.

4. The metal-ceramic composite according to claim 1, wherein the metal coating is a copper or aluminum coating.

5. A reaction layer exists between the ceramic substrate and the metal coating, and the reaction layer is composed of one or more elements selected from Ti, Hf, Zr, Nb, V, Ta, and Ce. ＲＳ A metal-ceramic composite according to claim 1, comprising the above.

6. It is a semiconductor module, The metal-ceramic composite according to claim 1, A semiconductor module comprising one or more semiconductor components.

7. The semiconductor module according to claim 6, further comprising a casting compound, the casting compound in contact with the surface of the ceramic substrate of the metal-ceramic composite exposed by the recess.

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