Metal-ceramic composite material

Abstract

The present invention relates to a metal-ceramic composite material comprising: a ceramic substrate comprising a front surface and a back surface and comprising silicon nitride; and the metal coating is positioned on the front surface of the ceramic substrate. Wherein the metal coating has at least one recess, and a surface of the ceramic substrate is exposed through the recess, the ceramic substrate displays a Si2p signal in a range of 96 eV to 107 eV in an energy spectrum (hereinafter also referred to as XPS spectrum) recorded by X-ray photoelectron spectroscopy at least in the region of the recess, wherein the Si2p signal has the following: one or more peaks each having a maximum in the range of 98.0 eV to 100.0 eV; one or more peaks each having a maximum value in the range of 101.0 eV to 102.2 eV; and one or more peaks each having a maximum value in the range of 102.5 eV to 104.0 eV.

Description

[0001] The present invention relates to a metal-ceramic composite material, which can be used as a ceramic circuit carrier in power electronic devices.

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

[0003] Since ceramic materials such as alumina, aluminum nitride, and silicon nitride have much higher thermal conductivities than the polymers used to produce conventional printed circuit boards, ceramic circuit carriers are often used in power modules.

[0004] Silicon nitride-based ceramic substrates have very high mechanical strength, along with high thermal conductivity, and are therefore very suitable for applications in power electronic devices.

[0005] Silicon nitride-based ceramic substrates are described, for example, in the following publications:

[0006] N. Chasserio et al., “Ceramic Substrates for High-Temperature Electronic Integration”, Journal of Electronic Materials, Vol. 38 (2009), pp. 164 - 174;

[0007] K. Hirao et al., “High Thermal Conductivity Silicon Nitride Ceramics”, Journal of the Korean Ceramic Society, Volume, Vol. 49 (2012), pp. 380 - 384;

[0008] Y. Zhou et al., “Development of high-thermal-conductivity silicon nitride ceramics”, Journal of Asian Ceramic Societies, 3 (2015), pp. 221 - 229.

[0009] Silicon nitride-based ceramic substrates are commercially available, showing a good compromise between high mechanical strength and high thermal conductivity and can be used in electronic components.

[0010] A ceramic circuit carrier contains a ceramic substrate which is provided with metal layers on at least one side thereof, usually on both sides. 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 connected to a heat sink. The ceramic substrate electrically insulates the metal layers from each other.

[0011] It is known to those skilled in the art that a metallized ceramic substrate serving as a ceramic circuit board is produced, for example, by bringing the front and back sides of the ceramic substrate into contact with a metal film (such as a copper film or an aluminum film) and bonding them together. The bonding of the metal foil material is achieved, for example, by eutectic bonding or active metal brazing (AMB). If the metal film is a copper film, eutectic bonding is also referred to as 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. Metallized ceramic substrates produced using the DCB or AMB process are sometimes also referred to as DCB substrates (alternatively: DBC substrates) or AMB substrates.

[0012] The metallization of silicon nitride substrates is usually carried out by active metal brazing.

[0013] The active metal solder contains, in addition to main components such as Cu, Ag or Au, one or more elements that can react with the ceramic to form an adhesion-promoting reaction layer (see, for example, Technical Ceramics Guide, Chapter 8.2.4.3 ("Active metal brazing") in the Ceramic Industry Association, pages 203 - 204, 2003, Fahner Verlag). Reactive elements such as hafnium (Hf), titanium (Ti), zirconium (Zr), niobium (Nb), cerium (Ce), tantalum (Ta) and vanadium (V) are used. When metallizing a silicon nitride substrate by active metal brazing, the reaction layer contains, for example, nitrides, oxynitrides and / or silicides of the reactive elements ( et al., "Active metal brazing of copper with aluminum nitride and silicon nitride ceramics", Keramische Zeitschrift, 63(5), 2011, 334 - 342).

[0014] The metal layer carrying the semiconductor component includes one or more recesses and is thus also referred to as a structured metal coating. For example, conductor tracks of metal are formed on a ceramic substrate by structuring. Adjacent conductor tracks are spatially separated by the recesses and are thus electrically insulated from each other. Structuring of the AMB substrate can be carried out, for example, in a two-stage process, in which in a first step, the metal layer is first removed in a defined area (for example, using a first etching solution), and then in a second step, the adhesion-promoting layer produced by the active metal soldering process is removed (for example, using a second etching solution). By removing the metal layer and (if applicable) the adhesion-promoting layer, the ceramic substrate is exposed again in the defined area.

[0015] Modules based on ceramic circuit carriers used in power electronics can be encapsulated as part of a packaging process, for example, by embedding the power module into a casting material.

[0016] For example, embedding into a casting material increases the electrical breakdown strength. In addition, the semiconductor component and the metal conductor tracks are protected from moisture and are mechanically stable.

[0017] In the areas exposed by structuring, the ceramic substrate is in direct contact with the casting material. When operating the power module, significant temperature fluctuations can occur. Since ceramic materials and casting materials typically have significantly different coefficients of thermal expansion, these temperature fluctuations cause mechanical stresses to occur at the interface between the ceramic and the casting material. This in turn can cause the casting material to become at least partially detached from the ceramic substrate and form cavities. Moisture penetrating these cavities can damage the power module. In addition, the electrical breakdown strength can be significantly reduced, at least locally. This is particularly problematic when moisture condenses in one of the recesses of the metal coating, which separates adjacent conductor tracks or chip carrier areas from each other.

[0018] As described above, silicon nitride-based ceramic substrates are used as circuit carriers in power electronics due to their very high mechanical strength and high thermal conductivity. In order to fully utilize their potential as circuit carriers, it is desirable that after embedding into a casting material, there is a high adhesion strength between the casting material and the silicon nitride surface.

[0019] An object of the present invention is to provide a metallized silicon nitride-containing ceramic substrate having improved waterproofness. In particular, waterproofness should be provided even if the casting material separates from the ceramic surface in the area of the recesses in the metal coating.

[0020] This object is achieved by a metal-ceramic composite material, which contains: a ceramic substrate that includes a front side and a back side and contains silicon nitride; a metal coating that is located on the front side of the ceramic substrate. The metal coating has at least one recess, and the surface of the ceramic substrate is exposed through the recess. The ceramic substrate shows a Si2p signal in the range of 96 eV to 107 eV in an energy spectrum (hereinafter also referred to as an XPS spectrum) recorded by X-ray photoelectron spectroscopy, at least in the region of the recess. The Si2p signal has the following components: one or more peaks each having a maximum value in the range of 98.0 eV to 100.0 eV; one or more peaks each having a maximum value in the range of 101.0 eV to 102.2 eV; one or more peaks each having a maximum value in the range of 102.5 eV to 104.0 eV.

[0021] The signal of an element in an XPS spectrum is affected by its oxidation state and its chemical environment (such as its chemical bonding partner). For example, if the Si atoms present in the ceramic substrate have a uniform oxidation state and a consistent chemical environment, a Si2p signal with a relatively narrow half-width would be expected in the XPS spectrum. This applies to conventional silicon nitride-based ceramic substrates. Even after contact with an etching medium, for example, when removing the metal coating on silicon nitride, the XPS spectrum usually shows a Si2p signal with a small half-width.

[0022] Within the scope of the present invention, it has been recognized that treating the ceramic substrate with an ultrashort-pulse laser can lead to a significant increase in the hydrophobicity of the treated silicon nitride surface. This indicates, for example, that the wetting angle of water is significantly increased compared to untreated silicon nitride ceramics or silicon nitride ceramics in contact with an etching medium. This results in improved water repellency of the silicon nitride ceramics.

[0023] Furthermore, within the scope of the present invention, it has been recognized that in the Si2p signal of the XPS spectrum of a laser-treated hydrophobic silicon nitride surface, additional peaks appear that are not present in the Si2p signal of untreated or etching-medium-treated silicon nitride ceramics.

[0024] In the XPS spectra of untreated silicon nitride ceramics and silicon nitride ceramics in contact with an etching medium, the Si2p signal basically shows only one peak, the maximum value of which is in the range of 101.0 eV to 102.2 eV. In the XPS spectrum of a silicon nitride ceramic that has been treated with a pulsed laser and exhibits a significantly higher water wetting angle due to this treatment, additional peaks are observed in the Si2p signal, the maximum values of which are in the range of 98.0 eV to 100.0 eV and in the range of 102.5 eV to 104.0 eV.

[0025] For example, in the ranges of 98.0 eV to 100.0 eV, 101.0 eV to 102.2 eV, and 102.5 eV to 104.0 eV, there is at least one peak, but not more than two peaks, which have a maximum value within the relevant range.

[0026] In another exemplary embodiment, in the ranges of 98.0 eV to 100.0 eV, 101.0 eV to 102.2 eV, and 102.5 eV to 104.0 eV, there is only a single peak, which has a maximum value within the relevant range.

[0027] In one exemplary embodiment, the following applies:

[0028] I 1 / I ges ≥0.02;

[0029] 2.0 ≤ I 2 / I 1 ≤ 8.0; provided that (I 1 + I 2 ) / I ges ≤ 0.85;

[0030] (I 1 + I 2 + I 3 ) / I ges ≥ 0.95;

[0031] where,

[0032] I ges is the total intensity of the Si2p signal;

[0033] I 1 is the total intensity of the peaks that each have a maximum value in the range of 98.0 eV to 100.0 eV;

[0034] I 2 is the total intensity of the peaks that each have a maximum value in the range of 101.0 eV to 102.2 eV;

[0035] I 3 is the total intensity of the peaks that each have a maximum value in the range of 102.5 eV to 104.0 eV.

[0036] The total intensity I of the Si2p signal ges is obtained from the sum of the intensities of all the peaks that make up the Si2p signal.

[0037] The intensity of a peak is the area under that peak.

[0038] If there is only one peak with a maximum value in the range of 98.0 eV to 100.0 eV of the Si2p signal, then the total intensity I1 corresponds to the intensity of that peak. If there are two peaks in total, each having a maximum value in the range of 98.0 eV to 100.0 eV, then the total intensity I 1 corresponds to the sum of the intensities of the two peaks. The total intensity I 2 and I 3 are measured in the same manner in the ranges of 101.0 eV to 102.2 eV and 102.5 eV to 104.0 eV.

[0039] For example, the following apply:

[0040] I 1 / I ges ≥0.05;

[0041] 2.5 ≤ I 2 / I 1 ≤ 7.0, provided that (I 1 +I 2 ) / I ges ≤ 0.80;

[0042] (I 1 +I 2 +I 3 ) / I ges ≥ 0.95.

[0043] In another exemplary embodiment, the following apply:

[0044] 2.0 ≤ I 2 / I 1 ≤ 8.0

[0045] 0.40 ≤ (I 1 +I 2 ) / I ges ≤ 0.85;

[0046] (I 1 +I 2 +I 3 ) / I ges ≥ 0.95

[0047] For example, the following apply:

[0048] 2.5 ≤ I 2 / I 1 ≤ 7.0

[0049] 0.50 ≤ (I 1 +I 2 ) / I ges ≤ 0.80;

[0050] (I 1 +I 2 +I 3) / I ges ≥0.95

[0051] In another exemplary embodiment, the following applies:

[0052] 0.05 ≤ I 1 / I ges ≤ 0.20

[0053] 0.20 ≤ I 2 / I ges ≤ 0.70;

[0054] (I 1 + I 2 + I 3 ) / I ges ≥ 0.95.

[0055] For example, the ceramic substrate contains at least 70 wt%, more preferably at least 80 wt% proportion of silicon nitride.

[0056] The silicon nitride is present, for example, in the β-phase (β-silicon nitride).

[0057] Optionally, the ceramic substrate may contain one or more metal oxides. These oxides are added, for example, as sintering aids during the production of the ceramic substrate. For example, the ceramic substrate contains 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., SiO 2 ) or silicate.

[0058] The ceramic substrate has, for example, a thickness in the range of 0.1 mm to 1.0 mm.

[0059] On the front side of the ceramic substrate, there is a metal coating that includes at least one recess such that the surface of the ceramic substrate is exposed through the recess. This metal coating is also referred to as a structured metal coating. A semiconductor component can be attached to the structured metal coating.

[0060] Optionally, the metal coating can also be used on the back side of the ceramic substrate. The back side 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 preferred that the back side metal coating does not include such recesses.

[0061] The metal coating present on the front side and optionally on the back side of the ceramic substrate is, for example, a copper coating or an aluminum coating. The metal coating has a thickness, for example, in the range of 0.05 mm to 1.5 mm, more preferably 0.2 mm to 0.8 mm.

[0062] If the metal coating is a copper coating, it has a copper content of, for example, at least 97 wt%, more preferably at least 99 wt%.

[0063] If the metal coating is an aluminum coating, it has an aluminum content of, for example, at least 97 wt%, more preferably at least 99 wt%.

[0064] Methods known to those skilled in the art can be used to apply the metal coating to the front side and optionally the back side of the ceramic substrate.

[0065] For example, a metal foil (e.g., a copper foil or an aluminum foil) is bonded to the front side of the ceramic substrate by active metal brazing.

[0066] In active metal brazing, for example, an active metal solder is used to form a connection between the metal foil and the ceramic substrate at a temperature of about 600 °C to 1000 °C. Due to their alloy composition, active metal solders are able to wet non-metallic inorganic materials such as ceramic substrates. In addition to the main components such as copper, silver, and / or gold, active metal solders also contain one or more active metals such as Hf, Ti, Zr, Nb, V, Ta, or Ce, which can react with the ceramic substrate to form a reaction layer.

[0067] Preferably, the reaction layer produced by active metal brazing is present between the metal coating and the front side of the ceramic substrate. The reaction layer contains, for example, one or more elements E RS , 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. A particularly preferred element E in the reaction layer RS is titanium. For example, the element E RS is present in the reaction layer in the form of nitrides, oxynitrides, and / or silicides. For example, the reaction layer contains a total of at least 50 wt% of the element E RS . For example, the reaction layer contains a total of at least 70 wt%, more preferably at least 85 wt%, of nitrides, oxynitrides, and silicides of the element ESR. In power electronic device semiconductor modules, the migration of silver can cause problems. Therefore, it may be preferred that the reaction layer contains silver in a proportion of no more than 5 wt%, more preferably no more than 1 wt%, or even contains no silver.

[0068] The surface of the exposed ceramic substrate is carried out, for example, in multiple steps. First, the metal coating is removed, for example, by etching, and the reaction layer formed during active metal brazing is exposed. Then, the exposed reaction layer is removed, for example, by etching or laser ablation. Preferably, an ultrashort pulse laser (e.g., an IR picosecond or femtosecond laser) is used to remove the exposed reaction layer.

[0069] In order to electrically insulate the recessed part - opened area of the metal coating, it is sufficient to perform material removal with a pulsed laser only at such times or under such conditions until the conductive material in the treated area has been completely removed, while avoiding modification of the silicon nitride on the surface of the ceramic substrate.

[0070] However, within the scope of the present invention, the treatment using a pulsed laser not only exposes the surface of the ceramic substrate but also modifies the silicon nitride on the surface of the ceramic substrate. As a result of this modification, the ceramic substrate shows a Si2p signal in the XPS spectrum, at least in the area of the recess, and this spectrum has additional peaks with maxima in the ranges of 98.0 eV to 100.0 eV and 102.5 eV to 104.0 eV. In order to produce a cermet substrate having a Si2p signal according to the present invention in the XPS spectrum, it has proven advantageous that the pulses of the laser beam have an energy density of at least 2 J / cm 2 of, for example, in the range from 2 J / cm 2 to 7 J / cm 2 . The pulse frequency of the laser beam is, for example, 1000 kHz. The area of the recess where the ceramic substrate shows a Si2p signal according to the present invention includes, for example, at least 50%, more preferably at least 70% of the surface of the ceramic substrate exposed through the recess, or may even include substantially the entire surface of the ceramic substrate exposed through the recess.

[0071] Within the scope of the present invention, it is also possible to first expose the surface of the ceramic substrate by a single - stage or multi - stage etching process and then treat the exposed surface of the ceramic substrate with a pulsed laser beam until a Si2p signal according to the present invention is achieved in the XPS spectrum.

[0072] However, for reasons of method efficiency, it may be preferred to use a pulsed laser to expose both the surface of the ceramic substrate and to modify the silicon nitride on the surface of the ceramic substrate.

[0073] The exposed surface of the ceramic substrate having a Si2p signal according to the present invention in the XPS spectrum shows a higher water wetting angle. This results in better water resistance of the metal - ceramic composite.

[0074] The present invention also relates to a semiconductor module, which contains: the above - mentioned metal - ceramic composite material, one or more semiconductor components.

[0075] Preferably, the semiconductor module contains a casting material, wherein the casting material contacts the surface of the ceramic substrate of the metal - ceramic composite material exposed through the recess.

[0076] The molding materials for electronic components are known to those skilled in the art. The molding materials contain, for example, polymers (e.g., thermoplastic polymers or thermosetting polymers). For example, the molding materials contain optionally cured epoxy resins or silicone resins, polyurethanes or inorganic cements (e.g., phosphate cements).

[0077] Measurement method

[0078] Measurement of XPS spectrum

[0079] The recording and evaluation of the XPS spectra are carried out as follows:

[0080] In preparation for the measurement using X-ray photoelectron spectroscopy, the ceramic sample is cut into a square with an edge length of 2 (+ / - 0.1) cm x 2 (+ / - 0.1) cm, such that an exposed Si 3 N 4 ceramic area is obtained. The dust on the specimen is blown off with nitrogen. The specimen is glued to the sample holder using a non-conductive adhesive tape. The X-ray photoelectron spectrum is recorded on a PHI 5800 ESCA from Physical Electronics with a Mg anode (monochromatic Kα = 1.253 keV) as the source. First, the total spectrum of the specimen (range 0 eV to 1400 eV) is recorded. Conclusions about the elements present on the examined upper side of the specimen are drawn from the total spectrum. Then, the detailed spectra of the specimen are recorded in the energy range where the signals can be identified in the total spectrum. To record the detailed spectra, an X-ray beam (200 μm diameter; 50 W, 15 kV; measurement time: 25 minutes to 40 minutes (e.g., 30 minutes); 20 ms integration time / measurement point) is used, the peak-noise setting is activated and a neutralizer (a combination of Ar+ and e- with low kinetic energy) is used. The spectra are evaluated using the analysis software CasaXPS (version 5 2.3.224PR1.0; Casa Software Ltd.). The C-C / C-H component of the C 1s signal (ubiquitously present) is normalized to 284.8 eV as a reference, and the binding energies of the detailed spectra are shifted accordingly. Background correction is performed using the Shirley function. Peaks are generated from the obtained signals using the analysis software. The number of peaks is adjusted based on a fitting model from the literature (XPS-NIST10 database), and the peaks are assigned to elements or compounds. The analysis software is used to calculate the peak areas of the generated peaks, taking into account the relative sensitivity factors.

[0081] Composition of the adhesion-promoting layer

[0082] The composition of the adhesion-promoting layer is determined by energy-dispersive X-ray spectroscopy (EDX) in combination with scanning electron microscopy (SEM-EDX).

[0083] In SEM-EDX, a focused primary electron beam is rastered (scanned) point by point over the sample surface. Scattered electrons are detected using a detector, and the number of electrons per pixel results in a microscopic image of the sample surface displayed in gray scale. In addition, the primary electron beam excites the sample to emit characteristic X-ray radiation, and the elements in the sample and their weight ratios can be determined by analyzing the energy spectrum using an EDX detector. For the examination, for example, a scanning electron microscope (JSM-6060SEM, JEOL Ltd) with a silicon drift EDX detector (NORAN, Thermo Scientific Inc) and analysis software (Pathfinder Mountaineer EDS System, version 2.8, for example, Thermo Scientific Inc) is used. For scanning electron microscopy, the following settings are used: magnification: 1000 times, acceleration voltage = 15 kV, working distance = 10 mm, spot size (50 - 60) (set to achieve 25% + / - 5% of the dead time of the EDX detector). The following settings of the EDX detector are used to detect the EDX spectrum: live time = 30 s, rate = automatic, low energy cut-off = 100 keV, high energy cut-off = automatic (per SEM acceleration voltage).

[0084] With the aid of SEM-EDX, the composition of the adhesion-promoting layer can be determined both qualitatively (detecting certain elements and phases, such as the metal nitride phase present in the adhesion-promoting layer) and quantitatively. For example, the measurements are carried out at at least 10 points on the adhesion-promoting layer. Examples

[0085] Five individual silicon nitride substrates (S1, S2, S3, S4, and S5) are separated from a silicon nitride starting substrate having a predetermined breaking point for separation. The ceramic substrates S1 to S5 have matching dimensions (174 mm × 139 mm × 0.32 mm).

[0086] Ceramic substrate S1 is used in Comparative Example 1 (VB1), ceramic substrate S2 is used in Example 1 according to the invention (EB1), ceramic substrate S3 is used in Example 2 according to the invention (EB2), and ceramic substrate S4 is used in Comparative Example VB2.

[0087] For each of the individual silicon nitride substrates S1 to S4, the Si2p signal in the XPS spectrum is measured in the area of the front side that is re-exposed later after metallization. The XPS-Si2p signal is also measured in the corresponding area on the ceramic surface of substrate S5.

[0088] In each of these substrates S1 to S5, the Si2p signal in the XPS spectrum shows only one peak. The maximum values of these peaks are substantially the same and are at 101.8 + / - 0.1 eV.

[0089] The silicon nitride substrate is metallized by the same active metal brazing process under the following conditions.

[0090] On one side of the ceramic substrate, an active metal brazing paste is applied by screen printing over an area measured as 168 mm x 130 mm and pre-dried at 125 °C for 15 minutes. The active metal brazing paste consists of 67 wt% copper powder, 19.8 wt% tin powder, 3.7 wt% titanium hydride, and 9.5 wt% organic carrier. The thickness of the paste after pre-drying is 25 μm + / - 5 μm. Subsequently, a copper film made of oxygen-free high-conductive copper with a purity of 99.99% and dimensions of 170 mm x 132 mm x 0.3 mm is placed on the pre-dried paste. Then the resulting arrangement is flipped, and the paste is similarly applied to the opposite side of the ceramic substrate by screen printing, pre-dried, and assembled using the copper film to obtain a sandwich arrangement. The sandwich arrangement is weighted with a 1 kg weight, fired at a maximum temperature of 910 °C for 20 minutes, and then cooled to room temperature to obtain an unstructured metal-ceramic composite. Due to production by active metal brazing, an adhesion-promoting reaction layer exists between the metal coating and the ceramic substrate. It contains titanium (e.g., in the form of a nitride).

[0091] Each of the three metal-ceramic composites is subjected to a first structuring process using an etching solution containing CuCl 2 The metal coating in the etched area on the front side of the ceramic substrate is removed. However, the reaction layer produced by the active metal brazing process is not removed by the etching solution containing CuCl 2

[0092] In Comparative Example VB1, the exposed reaction layer is removed using an etching solution containing ammonium fluoride, fluoboric acid, and hydrogen peroxide.

[0093] In Examples EB1 and EB2 according to the present invention and Comparative Example VB2, the exposed reaction layer is removed by treatment with an ultrashort pulse laser. The laser pulses in Examples EB1 and EB2 according to the present invention have an energy density of 2 J / cm 2 and 4 J / cm 2 while in Comparative Example VB2, pulses with an energy density of 9 J / cm 2 are used. The pulse frequency is 1000 kHz in each case.

[0094] ​XPS spectra were recorded on the exposed ceramic surfaces of Examples EB1 to EB2 and Comparative Examples VB1 and VB2 according to the present invention, and the wetting angles with water were determined.

[0095] The wetting angle was determined using an OCA 15EC contact angle measurement device from Dataphysics. The determination was carried out using three test liquids: distilled water, CH 2 I 2 (diiodomethane), and C 2 H 4 (OH) 2 anhydrous ethylene glycol. For each liquid, at least 20 droplets were used to measure the contact angle in order to subsequently determine the average value.

[0096] The XPS spectra were evaluated based on the Si2p signal.

[0097] The results are summarized in Table 1 below.

[0098] Table 1: XPS-Si2p signal on the silicon nitride surface and wetting angle with water

[0099]

[0100]

[0101] By pulsed laser treatment, the structures of the silicon nitride substrates in Examples EB1 and EB2 according to the present invention were modified, and thus showed significantly different Si2p signals compared to the starting substrates and the substrates exposed by etching.

[0102] Due to pulsed laser treatment, the silicon nitride substrate of Comparative Example VB2 also showed a changed Si2p signal in the XPS spectrum compared to the original substrate. However, this Si2p signal is not according to the present invention because it does not have a peak with a maximum value in the range of 98.0 eV to 100.0 eV.

[0103] The silicon nitride surface with a Si2p signal according to the present invention showed significantly higher water wetting angles compared to the silicon nitride surfaces of the comparative examples. This gives the silicon nitride ceramic better water resistance.

Claims

1. A metal-ceramic composite material, comprising: a ceramic substrate including a front side and a back side and containing silicon nitride, a metal coating, the metal coating being located on the front side of the ceramic substrate, in The metal coating has at least one recess, and the surface of the ceramic substrate is exposed through the recess, The ceramic substrate shows, at least in the region of the recessed portion, a Si2p signal in a spectrum recorded by X-ray photoelectron spectroscopy in a range of 96 eV to 107 eV, The Si2p signal has the following terms: one or more peaks each having a maximum value in the range of 98.0 eV to 100.0 eV, one or more peaks each having a maximum value in the range of 101.0 eV to 102.2 eV, Each has one or more peaks with a maximum value in the range of 102.5 eV to 104.0 eV.

2. The metal-ceramic composite material according to claim 1, wherein the following relationship is satisfied: I1 / I ges ≥0.02; 2.0≤I2 / I1≤8.0; the condition is (I1+I2) / I ges ≤0.85; (I1+I2+I3) / I ges ≥0.95; in I ges is the total intensity of the Si2p signal; I1 is the total intensity of the peaks each having a maximum value in the range of 98.0 eV to 100.0 eV; I2 is the total intensity of the peaks each having a maximum value in the range of 101.0 eV to 102.2 eV; I3 is the total intensity of the peaks each having a maximum value in the range of 102.5 eV to 104.0 eV.

3. The metal-ceramic composite material according to claim 1 or 2, wherein in the ranges of 98.0 eV to 100.0 eV, 101.0 eV to 102.2 eV and 102.5 eV to 104.0 eV, there are no more than two peaks having maximum values ​​in the relevant ranges.

4. The metal-ceramic composite material according to any one of the preceding claims, wherein the ceramic substrate contains the silicon nitride in a proportion of at least 70% by weight.

5. The metal-ceramic composite material according to any one of the preceding claims, wherein the metal coating is a copper or aluminum coating.

6. The metal-ceramic composite material according to any one of the preceding claims, wherein there is a reaction layer between the ceramic substrate and the metal coating, wherein the reaction layer contains one or more elements selected from Ti, Hf, Zr, Nb, V, Ta and Ce. RS .

7. A semiconductor module, comprising: The metal-ceramic composite material according to any one of claims 1 to 6, One or more semiconductor components.

8. The semiconductor module according to claim 7, further comprising: A mold material is provided, wherein the mold material contacts the surface of the ceramic substrate of the metal-ceramic composite material exposed through the recess.

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