Mola sputtering target

Abstract

The invention discloses a sputtering target produced by powder metallurgy, the sputtering target containing 0.3-10 wt.% of an oxygen-containing lanthanum compound (La), the remainder being molybdenum (Mo) and unavoidable impurities, characterized in that the sputtering target has an Mo phase and an La phase, an average grain size of the Mo grains in the Mo phase being 1-200 µm, and the sputtering target having an isotropic microstructure.

Description

[0001] MoLa sputtering target

[0002] The present invention relates to a powder-metallurgically produced Mo (molybdenum)La (lanthanum) sputtering target (hereinafter referred to as MoLa), comprising Mo and an oxygen-containing lanthanum compound, and its use for the production of high-temperature stable thin films. The present invention further relates to a method for producing a MoLa sputtering target via a powder-metallurgical route.

[0003] Sputtering, also known as cathode sputtering, is a physical process in which atoms are ejected from a sputtering target by bombardment with high-energy ions and transition into the gas phase. In DC sputtering (direct current sputtering), a direct current voltage of several hundred volts is applied between the target and the substrate to be coated in a vacuum chamber; it is therefore also called DC sputtering. The target forms the negatively charged electrode and the substrate the positively charged electrode. Impact ionization of the atoms of an inert gas (e.g., argon) creates a plasma in the gas space of the vacuum chamber, the components of which are negatively charged electrons and positively charged gas ions, such as Ar. +The applied DC voltage accelerates the particles towards the substrate or target. A continuous current of positive ions and argon atoms then strikes the target. Upon impact, momentum transfer ejects particles from the target, which move away from the target towards the substrate and are deposited there as a thin layer (deposition). However, this method is only applicable to electrically conductive target materials.

[0004] Conductive layers with high temperature stability and improved high-temperature properties have become important, for example, in the development of wireless SAW (Surface Acoustic Wave) temperature sensors. Although layers made of pure molybdenum, unlike metals with low melting points, exhibit high temperature stability, recrystallization occurs above a certain temperature (approx. 600°C) in practical applications, leading to a change in the layer's properties.

[0005] It is known that oxide or carbide particles (as local barriers to diffusion and dislocation movement) can be used for dispersion strengthening in pure molybdenum alloys, thereby improving the thermomechanical properties of such materials. When using lanthanum oxide as the dispersoid, layers of molybdenum and lanthanum oxide are produced either by co-sputtering molybdenum and lanthanum oxide targets or by alternating (reactive) sputtering of molybdenum and lanthanum targets. A disadvantage of co-sputtering is that the lanthanum oxide targets degrade very quickly. A disadvantage of alternating sputtering of molybdenum and lanthanum targets is that the lanthanum layer must subsequently be oxidized to a lanthanum oxide layer before the next molybdenum layer can be sputtered. However, if water or steam is still present in the sputtering chamber, the lanthanum layer can be oxidized to a lanthanum oxide layer before the next molybdenum layer can be sputtered.If humidity is present, the lanthanum oxide is immediately converted into lanthanum hydroxide.

[0006] Sputtering targets containing both molybdenum and lanthanum oxide are also known from the prior art.

[0007] Patent application CN114351095 A discloses a Mo alloy target comprising Mo and at least one of the dopants selected from Al₂O₃, ZrÜ₂, and / or LazO₃. However, the exact proportion of these dopants is not disclosed. While the application states that the proportion of these elements does not exceed 10%, it does not specify whether this is expressed as wt.%, vol.%, or mol.%.

[0008] Generally, the term "small quantity" is used. The dopants Al₂O₃, ZrÜ₂, and / or La₂Ü₃ inhibit the growth of the molybdenum particles, allowing for the production of a nanoscale powder. This enables the manufacture of a nanocrystalline molybdenum alloy target with an ultrafine grain structure (grain size < 300 nm). According to this patent application, these nanocrystalline materials are superior to conventional (coarser-grained) materials with regard to surface properties. The examples in this patent application show the dopants Al₂O₃, ZrÜ₂, or a combination of Al₂O₃ and ZrÜ₂. However, the production of such nanocrystalline powders is very complex, and the powdery form of the nanocrystalline powders makes them difficult to process.

[0009] Patent application CN106591786 A describes a manufacturing process for a doped molybdenum target material containing 1 to 6 wt% lanthanum oxide relative to the amount of molybdenum trioxide used. The application discloses a process in which twice as much molybdenum trioxide as molybdenum powder is used. When molybdenum trioxide is used, molybdenum dioxide is subsequently formed, which must then be reduced to molybdenum in a further process step. Whether this reduction is complete is not further specified in the patent application (i.e., molybdenum trioxide or dioxide could still be present in the target). One step of this process discloses that lanthanum oxide is reduced to lanthanum powder (step 3). The total proportion of lanthanum oxide in the final target is therefore not disclosed. After sintering, the material is rolled so that the sputtering target has a deformed structure.In contrast, the sputtering target according to the invention has an isotropic (globulitic) microstructure.

[0010] Two disadvantages arise when using targets made of lanthanum oxide and molybdenum, which are not mentioned in the aforementioned patent applications. First, DC sputtering is only applicable to electrically conductive target materials (the addition of LazOs reduces the conductivity of the target material), and second, lanthanum oxide reacts immediately with atmospheric moisture or water vapor to form lanthanum hydroxide. However, lanthanum hydroxide is undesirable as a (sputtering) end product because it impairs the uniform deposition behavior of lanthanum oxide and molybdenum and reduces its effectiveness as a dispersoid.

[0011] The object of the present invention is to provide a MoLa sputtering target that exhibits sufficient electrical conductivity and high density, and that displays a uniform or homogeneous distribution of a Mo phase and a La phase throughout the entire volume of the target. This enables uniform sputtering, as both the Mo phase and the La phase are simultaneously removed from the sputtering target in the same quantity. Uniform sputtering, or uniform sputtering behavior, is understood to mean that the individual grains or areas of the sputtering target can be removed at the same rate, so that no relief structure forms on the sputtered surface during the sputtering process. Furthermore, the target according to the invention contains an extremely small amount of lanthanum hydroxide, which exhibits different sputtering behavior and thus prevents uniform sputtering.

[0012] In particular, the object of the invention is to provide a sputtering target with which a very homogeneous layer can be produced, both with regard to chemical composition and layer thickness distribution.

[0013] A further object of the present invention is to provide a method that allows the simple and process-consistent fabrication of a sputtering target possessing the aforementioned properties. The technical object of the present invention is achieved by the subject matter of claim 1 and the method in claim 11. Advantageous embodiments of the invention are described in the dependent claims, which may be freely combined with one another.

[0014] According to the present invention, the powder metallurgically produced sputtering target comprises 0.3 to 10 wt.% of an oxygen-containing lanthanum compound (La), the remainder molybdenum (Mo) and unavoidable impurities, and is characterized in that the sputtering target has a Mo phase and a La phase, wherein an average grain size of the Mo grains in the Mo phase is 1 to 200 pm and the sputtering target has an isotropic microstructure.

[0015] Preferably, the sputtering target consists of 0.3 to 10 wt.% of an oxygen-containing lanthanum compound (La), the remainder being molybdenum (Mo), and a maximum of 0.1 wt.% unavoidable impurities. Oxygen is not considered an unavoidable impurity because the lanthanum is added in an oxygen-containing compound. The higher the amount of oxygen-containing La compound in the target, the higher the oxygen content. Preferably, the proportion of oxygen-containing lanthanum compound is more than 0.7 to 10 wt.%, and even more preferably 0.8 to 10 wt.%. At this proportion of oxygen-containing lanthanum compound, the electrical conductivity of the sputtering target is sufficient for uniform sputtering in DC mode, and the amount of unwanted lanthanum hydroxide produced is sufficiently low.

[0016] A powder metallurgy-produced sputtering target is a component whose manufacture involves pressing suitable starting powders into a compact and sintering the compact. The manufacturing process may also include further steps, such as mixing and homogenizing (e.g., in a plowshare mixer) the powders to be pressed. This results in a microstructure typical of this manufacturing process, known as an isotropic microstructure. The isotropic microstructure is defined by the fact that the grains are uniformly (globulitic), meaning there is no preferred orientation in the grain structure of the sputtering target. This means that the mechanical and thermal properties of the material are identical in all directions.This differs from the state of the art (see CN106591786) in which a preferred direction / forming structure of the grains results from a rolling step.

[0017] For a sputtering target, a homogeneous distribution of the elements and a high density are crucial. The structure of a sputtering target differs significantly from that of other molybdenum oxide products (such as wires, sheets, or rods). In these latter products, the processing and addition of lanthanum oxide result in enlarged, elongated particles (i.e., a fiber structure), which are essential for properties such as creep resistance and higher recrystallization temperature.

[0018] The advantage of the isotropic structure is a high uniformity of properties after deposition of the material onto a substrate to be coated.

[0019] The microstructure of the sputtering target within the meaning of this invention is the microstructure which can be analyzed in a simple manner known to those skilled in the art by means of a metallographic section and evaluation under a light microscope or scanning electron microscope.

[0020] In the case of the sputtering target according to the invention, the microstructure comprises only a Mo phase and an La phase, which are homogeneously distributed throughout the entire volume of the sputtering target. Strictly speaking, the La phase should actually be referred to as the LazOs phase or the LazOs / LafOHjs phase. However, for the sake of simplicity, it is referred to as the La phase. No mixed phases (containing both Mo and La) or intermetallic phases of Mo and LazOs and / or La(OH)3 occur. The Mo phase is the pure / elemental component Mo (i.e., Mo grains), as it is also used as a starting material. The La phase is either LazOs (as it is also used as a starting material) or a mixture of LazOs and La(OH)3. Lanthanum oxide is extremely hygroscopic and can readily and rapidly absorb water from its surroundings. Lanthanum oxide reacts rapidly in moist air to form lanthanum hydroxide.Furthermore, other phases, such as pores, may be present in the target material. The presence of a pure Mo phase and an La phase in a sputtering target according to the invention can be easily confirmed or excluded using X-ray diffraction (XRD) (taking into account the respective X-ray detection limit) with JCPDS cards. The powder metallurgically produced sputtering target exhibits a microstructure typical for powder metallurgical production. This fine-grained microstructure enables uniform sputtering of the target. The average grain size of the Mo grains in the Mo phase is between 1 and 200 pm, preferably between 1 and 50 pm, and particularly preferably between 1 and 30 pm. These grain sizes result in uniform sputtering behavior and thus in the deposition of very homogeneous layers with a uniform layer thickness.The average grain size of the Mo phase can be easily determined by a line sectioning method, e.g. according to ASTM E112-12, on a metallographic section.

[0021] The addition of 0.3 to 10 wt.% lanthanum oxide stabilizes the microstructure of the MoLa target, thus altering its recrystallization behavior compared to the base material molybdenum, specifically with regard to its thermomechanical behavior at extremely high temperatures. Although layers of pure molybdenum exhibit high temperature stability, recrystallization processes and subsequent changes in the deposited layers can occur at high temperatures (e.g., above 800°C) during application or in subsequent process steps. The addition of lanthanum oxide results in targets with a higher recrystallization temperature than pure molybdenum. This makes the targets according to the invention particularly suitable for high-temperature applications. If the amount of lanthanum oxide is below 0.3 wt.%, this effect is not detectable. If the amount of lanthanum oxide exceeds 10 wt.%, the recrystallization temperature is significantly higher.The conductivity of the sputtering target decreases significantly, severely impairing sputtering in DC mode. A quantity of more than 0.7 to 10 wt.% is preferred.

[0022] The term "unavoidable impurities" refers to impurities that can occur in the target due to the production process, such as accompanying elements or gases found in the raw materials used or introduced into the target through the tools or vessels used. A distinction can be made between metallic and non-metallic impurities. Non-metallic impurities can be gases such as C, N, H, S, etc. In the sputtering target according to the invention, the addition of LazOs (depending on the amount used) results in a somewhat higher oxygen content, which can be up to 18,000 pg / g (18,000 ppm by weight), but is preferably below 10,000 pg / g, and particularly preferably below 5,000 pg / g. For the other gases, the value is below 1,000 pg / g, preferably below 500 pg / g. Metallic impurities include, for example, Al, Cr, Cu, Fe, K, Mg, Ni, Si, V, Ti, W, Zr, etc.The proportion of such impurities is below 300 pg / g. In particular, the whey content of the impurities is less than 160 ppm.

[0023] Suitable methods for chemical elemental analysis are known to depend on the chemical elements to be analyzed. For the chemical analysis of elements such as Al, Fe, Cu, etc., ICP-MS (inductively coupled plasma mass spectrometry) or ICP-OES (inductively coupled plasma optical emission spectroscopy) was used. For the elements O or N, hot gas extraction analysis (see ASTM E1409-13) was applied. For the elements C (see ASTM E 1941-10) and S (see ASTM E 1019:2018), combustion analysis was used. The chemical analysis of the main components Mo and LazOs in the sputtering target according to the invention was carried out by means of X-ray fluorescence analysis (XRF).

[0024] As described above, the La phase can also contain a mixture of lanthanum oxide and lanthanum hydroxide. However, the proportion of lanthanum hydroxide in the sputtering target should be kept as low as possible, since this proportion negatively affects the sputtering behavior, particularly the homogeneity of the deposition. Therefore, it is very important to prevent the formation of lanthanum hydroxide as much as possible and to keep the proportion of La(OH)₃ in the La phase as low as possible. The surface area fraction of lanthanum hydroxide (La(OH)₃) in the La phase should be a maximum of 10%, measured against the cross-sectional area of ​​the target material. The La(OH)₃ fraction can range between 0.1% and 10%. Preferably, the surface area fraction of lanthanum hydroxide, measured against the cross-sectional area of ​​the target material, should be a maximum of 5%. The sputtering target according to the invention does not exhibit any intermetallic phases of La and Mo.

[0025] In another embodiment, the La phase has an area fraction of between 5 and 18%, measured against the cross-section of the target material. The cross-section of the material shows the area fraction in relation to the Mo phase and in relation to the La phase.

[0026] According to a further development, the sputtering target according to the invention has a density of at least 95% of the theoretical density. A density of more than 97%, preferably more than 98%, of the theoretical density is particularly advantageous. The theoretical density is the maximum achievable density of the MoLa target, provided that no internal voids and impurities (or intermetallic phases) form. The higher the density of the target, the more advantageous its properties. Targets with a low relative density have a relatively high proportion of pores, which can represent a virtual leak and / or a source of impurities and particles during the sputtering process. Furthermore, low-density targets tend to absorb water or other impurities, which can lead to process parameters that are difficult to control.Furthermore, the removal rate of material that is only slightly densified during the sputtering process is lower than that of material with a higher relative density.

[0027] The theoretical density of composite materials can be calculated from the densities of the individual pure metals or compounds and their weight fractions. The density can be determined, for example, using the Archimedes method by determining the weight of the target in air and water (here, the sample can preferably be embedded in paraffin; see DIN EN ISO 2738:2000-02).

[0028] The integration of a sputtering target according to the invention into various coating systems, and also for coating substrates with different geometries, places various geometric demands on the sputtering target. The target is preferably in the form of a planar sputtering target, for example as a cuboid, disk, or plate. However, it can also be in the form of a tubular target.

[0029] Thin-film materials (with a thickness typically less than 1000 nm) containing Mo-LazOs systems exhibit superior ductility, toughness, and creep resistance at high temperatures. The sputtering target according to the invention is therefore preferably used for the deposition of metallic thin films, and particularly preferably for the deposition of high-temperature resistant thin films, such as SAW temperature sensors, SAW sensor chips, and sensor antennas.

[0030] MoLa layers from the sputtering target according to the invention can also function as hydrogen trap layers, which is advantageous, for example, in hydrogen-sensitive oxide semiconductor layers.

[0031] The inventive process for producing the powder-metallurgically produced MoLa sputtering target, which comprises 0.3 to 10 wt.% of an oxygen-containing lanthanum compound (La), the remainder molybdenum (Mo) and unavoidable impurities, is characterized by the following steps: mixing Mo powder and an oxygen-containing lanthanum compound in powder form to form a powder mixture;

[0032] Compacting the powder mixture by applying pressure, heat or pressure and heat to form a blank, wherein the sputtering target has a Mo phase and a La phase, and wherein the average grain size of the Mo grains in the Mo phase is 1 to 200 pm and the sputtering target has an isotropic microstructure.

[0033] Before a powder mixture is produced, the oxygen-containing lanthanum compound is calcined, i.e., the compound is heated so intensely that it is completely dehydrated.

[0034] Consequently, after this step, LazOs powder is present. In a preferred embodiment, the lanthanum oxide powder is obtained by calcining lanthanum hydroxide. In this process, the lanthanum hydroxide is heated to a temperature exceeding 1000°C. This dehydrates the powdered lanthanum hydroxide.

[0035] The next step is to produce a powder mixture by mixing 0.3 to 10 wt.% LazOs powder with Mo powder until a homogeneous distribution of the components in the powder mixture is ensured.

[0036] The resulting powder mixture is then compacted. Compaction in the process according to the invention is carried out by applying pressure, heat, or pressure and heat. This can be achieved through various process steps, for example, pressing and sintering, cold isostatic pressing (CIP), hot isostatic pressing (HIP), hot pressing (HP), or spark plasma sintering (SPS), or a combination of these or other processes for compacting powder mixtures.

[0037] It has proven particularly advantageous that, in a process according to the invention for manufacturing the MoLa targets, the compaction step is carried out by hot pressing, spark plasma sintering, or hot isostatic pressing. Temperatures of 1000°C to 1800°C are used. Preferably, a pressure of 15 MPa or higher is employed. If the compaction step is carried out via HIP, pressures of up to 200 MPa can be used.

[0038] Sintering preferably takes place under vacuum, in an inert atmosphere, and / or in a reduced atmosphere. In this context, an inert atmosphere is understood to be a gaseous medium that does not react with the alloying elements, e.g., a noble gas.

[0039] A suitable reduced atmosphere is, in particular, hydrogen.

[0040] The method according to the invention makes it possible to produce a Mo-La sputtering target which has an isotropic microstructure in which the Mo phase and La phase are uniformly distributed. The average grain size of the Mo grains in the Mo phase is between 1 and 200 pm and preferably the sputtering target has a density of at least 95% of the theoretical density.

[0041] Further advantages and expediencies of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures.

[0042] The figures show

[0043] Fig. 1: Microstructure of a sputtering target according to the invention as shown in Example 1 in the

[0044] Scanning electron microscope (SEM) at 200x magnification;

[0045] Fig. 2 Example 1: Distribution of the elements Mo and La by EDX (energy-dispersive ionization)

[0046] X-ray spectroscopy mapping on the SEM at 500x magnification;

[0047] Fig. 3 X-ray diffractogram of a sputtering target according to the invention as shown in example

[0048] 1; pure Mo and LazOs (cubic and hexagonal) detectable, no La(OH)3 detectable;

[0049] Fig. 4 Example 2: Distribution of the elements Mo and La by EDX (energy-dispersive ionization)

[0050] X-ray spectroscopy mapping on the SEM at 500x magnification;

[0051] Fig. 5: X-ray diffractogram of a sputtering target according to the invention as shown in example

[0052] 2; pure Mo phase and LazOs (cubic and hexagonal) detectable, no La(OH)3 detectable;

[0053] Fig. 6: Example 3: Distribution of the elements Mo and La by EDX (energy-dispersive ionization)

[0054] X-ray spectroscopy mapping on the SEM at 500x magnification;

[0055] Fig. 7: X-ray diffractogram of a sputtering target according to the invention as shown in example

[0056] 3; pure Mo phase, LazOs (hexagonal) and La(OH)3 detectable;

[0057] PRODUCTION EXAMPLES

[0058] Example 1

[0059] In a first step, lanthanum hydroxide is calcined, i.e., La(OH)3 is heated to over 1000°C for a sufficient duration to obtain a LazOs powder. This LazOs powder has an average particle size of approximately 0.8 pm (D50 measurement according to Malvern). Subsequently, the LazOs powder and a molybdenum powder with an average particle size of less than 20 pm (D90 measurement according to Malvern) are used as starting materials. Immediately after calcination, 98.6 wt% molybdenum powder and 1.4 wt% LazOs powder are placed in a closed container (no vacuum) and mixed in a shaker. The powder mixture is then poured into a container and sintered at a pressure of approximately 15 MPa at 1800°C in a SPS ("Spark Plasma Sintering") system to obtain a consolidated target.

[0060] Lanthanum oxide is extremely hygroscopic and can therefore quickly absorb moisture from the air, causing it to convert back into lanthanum hydroxide. Therefore, the mixing and subsequent sintering steps should take place immediately one after the other.

[0061] The resulting disc-shaped, planar sputtering target has a relative density of 98.6%. The oxygen content is approximately 2000 pg / g, the carbon content 150 pg / g, and the water content approximately 160 pg / g. All other impurities are present in total at less than 100 pg / g.

[0062] The target produced in this way was used in a sputtering system and deposited as a metallic thin film (approx. 100 nm) onto thermally oxidized Si (SiOx). The sputtering target could be uniformly sputtered, resulting in a thin film in which Mo and LazOs were homogeneously distributed. No La(OH)3 could be detected. The thin film exhibits higher temperature stability compared to a pure molybdenum coating.

[0063] Fig. 1 shows the isotropic structure of the sputtering target produced according to this example. The microstructure shows Mo grains (gray) and LazOs grains (dark gray). The black color indicates pores resulting from the powder metallurgy process or artifacts created during the preparation of the micrograph.

[0064] Figure 2 shows the distribution of Mo and La from Example 1 using energy-dispersive X-ray spectroscopy on an SEM section. Since the oxygen is tightly bound to the La, it cannot be shown separately in a black and white representation. La (and the oxide bound to it) are shown in dark. The Mo grains appear light gray. The uniform distribution of the La and Mo phases is clearly visible. Figure 3 shows the X-ray diffraction pattern of this example and its evaluation by decomposing the diffractogram ms. The sample was analyzed using a Bruker D8 Advance 0-0 diffractometer with Cu radiation (Xcal = 0.15406 nm). The diffraction geometry is characterized by the following details.

[0065] - Primary optics: focusing polycapillary and UBC collimator (long version, width 1 mm),

[0066] - Secondary optics: axial 2.5° Soller slit, Lynx Eye XET detector in ID mode.

[0067] - Measurement mode: locked coupled, step size: 0.02°, time / step: 1 sec, sample rotation: 3 revolutions / min.

[0068] To clearly assign individual components to the peaks / phases, a search-match algorithm was used in the PDF (Powder Diffraction File)2 database (version 2020). PDF2 is a database for inorganic and organic diffraction data for phase identification and material characterization. The presence of the individual phases was confirmed by Rietveld refinement using the corresponding structural data (of Mo, LazOs (hexagonal (P321)) and LazOs (cubic (la-3))).

[0069] The dark gray curve shows 2Theta angles for pure molybdenum at 40.5°, 58° and 74°.

[0070] The dashed curve shows 2Theta angles for cubic lanthanum oxide at 27.4°; 31.9°; 45° and 54°.

[0071] The light gray curve shows 2Theta angles for hexagonal lanthanum oxide at 30°; 39.5°; 46°; 52° and 55.6°.

[0072] The points o correspond to the measured values ​​(radiation intensities) in the diffractometer.

[0073] The curve Y calc (light gray) corresponds to all measured values ​​(molybdenum, LazOs (hexagonal) and LazOs (cubic)) and shows the overall agreement.

[0074] The difference (diff) (bottom line) shows hardly any deviations, so the individual phases are well described.

[0075] This figure shows that the sputtering target consists of a pure Mo phase and a pure lanthanum oxide phase, with neither lanthanum hydroxide nor intermetallic phases forming during the production process.

[0076] This target was produced by sputtering on thermally oxidized Si with a layer thickness of approximately...

[0077] Deposited at 100 nm. Compared to a pure Mo layer, the layer exhibits improved layer stability, thermomechanical behavior, and creep behavior (especially at temperatures above 800°C).

[0078] Example 2

[0079] The production process is the same as in Example 1, except that 97.2 wt.% molybdenum powder with an average particle size of less than 20 pm (D90 measurement according to Malvern) and 2.1 wt.% lanthanum oxide with an average particle size of about 0.8 pm (D50 measurement according to Malvern) are mixed in a mixer.

[0080] The mixed powder is then sintered at a pressure of approximately 15 MPa and 1800°C in a Spark Plasma Sintering (SPS) system. The resulting sputtering target has a relative density of 98.9%. The oxygen content is approximately 3000 pg / g, and the water content is below 160 pg / g. All other impurities are below 100 pg / g. The planar round target has a diameter of approximately 110 mm.

[0081] Fig. 4 shows the distribution of Mo and La in an SEM section as determined by energy-dispersive X-ray spectroscopy (EDX). Since the oxygen is tightly bound to the La, it cannot be shown separately in a black and white representation. La (and the oxide bound to it) are shown in dark. The Mo grains appear light gray. The uniform distribution of the La and Mo phases is evident.

[0082] Fig. 5 shows the X-ray diffraction pattern of this example, as well as its evaluation. This was carried out analogously to Fig. 3 in Example 1.

[0083] The dark gray curve shows 2Theta angles for pure molybdenum at 40.5°, 58° and 74°.

[0084] The dashed curve shows 2Theta angles for cubic lanthanum oxide at 27.4°; 31.9°; 45° and 54°.

[0085] The light gray curve shows 2Theta angles for hexagonal lanthanum oxide at 30°; 39.5°; 46°; 52° and 55.6°.

[0086] The points ° correspond to the measured values ​​(radiation intensities) in the diffractometer.

[0087] The curve Y calc (light gray) corresponds to all measured values ​​(molybdenum, LazOs (hexagonal) and LazOs (cubic)) and shows the overall agreement.

[0088] The difference (diff) (bottom line) shows hardly any deviations, so the individual phases are well described. This figure shows that the sputtering target consists of a pure molybdenum phase and a pure lanthanum oxide phase, with neither lanthanum hydroxide nor intermetallic phases forming during the production process.

[0089] This target was also deposited by sputtering onto thermally oxidized silicon with a layer thickness of approximately 100 nm. Compared to a pure molybdenum layer, the resulting layer exhibits improved layer stability, thermomechanical behavior, and creep behavior (especially at temperatures above 800°C).

[0090] Example 3

[0091] The production process is the same as in Example 1, except that 90 wt.% molybdenum powder with an average particle size of less than 20 pm (D90 measurement according to Malvern) and 10 wt.% lanthanum oxide with an average particle size of about 0.8 pm (D50 measurement according to Malvern) are mixed in a mixer.

[0092] The mixed powder is then sintered at a pressure of approximately 15 MPa and 1800°C in a Spark Plasma Sintering (SPS) system. Afterwards, the sputtering target has a relative density of 97.5%. The oxygen content is approximately 18,000 pg / g, and the water content is below 160 pg / g. All other impurities are below 100 pg / g.

[0093] Fig. 6 shows the distribution of Mo and La as determined by energy-dispersive X-ray spectroscopy (EDX) in a SEM section. Since the oxygen and hydroxide components are tightly bound to the La, they cannot be shown separately in a black and white representation. La (and the oxide bound to it) and lanthanum hydroxide are shown in dark tones. The Mo grains appear light gray. The uniform distribution of the La and Mo phases is evident.

[0094] Fig. 7 shows the X-ray diffraction pattern of this example, as well as its evaluation. This is carried out analogously to Fig. 3 in Example 1. No cubic lanthanum oxide is detectable, but lanthanum hydroxide is.

[0095] The dark gray curve shows 2Theta angles for pure molybdenum at 40.5°, 58° and 74°.

[0096] The light gray curve shows 2Theta angles for hexagonal lanthanum oxide at 30°; 39.5°; 46°; 52° and 55.6°.

[0097] The dashed (light gray) curve shows no peaks for cubic lanthanum oxide. The dark gray dashed curve shows 2θ angles for lanthanum hydroxide at 27.5°, 28°, 31.8°, 39.6°, 42.5°, 47.3°, 48.9°, and 50°.

[0098] The points ° correspond to the measured values ​​(radiation intensities) in the diffractometer.

[0099] The curve Y calc (light gray) corresponds to all measured values ​​(molybdenum, LazOs (hexagonal) and LazOHs) and shows the overall agreement.

[0100] The difference (diff) (bottom line) shows hardly any deviations, so the individual phases are well described.

[0101] This figure shows that the sputtering target also forms lanthanum hydroxide phases, although no intermetallic phases of Mo and La have formed. Despite the large amount of lanthanum oxide, the sputtering target exhibits sufficient electrical conductivity to allow sputtering in DC mode.

[0102] This target was also deposited by sputtering onto thermally oxidized silicon with a layer thickness of approximately 100 nm. Compared to a pure molybdenum layer (despite the lanthanum hydroxide phases), the layer exhibits improved layer stability, thermomechanical behavior, and creep behavior (especially at temperatures above 800°C).

Claims

REQUIREMENTS 1. Powder metallurgically produced sputtering target, wherein the sputtering target comprises 0.3 to 10 wt.% of an oxygen-containing lanthanum compound (La), the remainder molybdenum (Mo) and unavoidable impurities, characterized in that the sputtering target has a Mo phase and a La phase, wherein an average grain size of the Mo grains in the Mo phase is 1 to 200 pm and the sputtering target has an isotropic microstructure.

2. Sputtering target according to claim 1, characterized in that the La phase comprises lanthanum oxide (LazOs) and lanthanum hydroxide (La(OH)3).

3. Sputtering target according to one of the preceding claims, characterized in that the La phase has an area fraction, measured on a cross-section of the target material, of between 5 and 18%.

4. Sputtering target according to one of the preceding claims, characterized in that the area fraction of La(OH)3 in the La phase, measured on a cross-section of the target material, is not more than 10%.

5. Sputtering target according to one of the preceding claims, characterized in that the proportion of oxygen-containing lanthanum compound is > 0.7 wt.% to 10 wt.%.

6. Sputter target according to any of the preceding claims, wherein the density of the sputter target is at least 95% of the theoretical density.

7. Sputter target according to any of the preceding claims, wherein the average grain size of the Mo grains in the Mo phase is between 1 and 50 pm.

8. Sputter target according to one of the preceding claims, characterized in that it is a planar sputter target.

9. Use of the sputtering target according to any one of claims 1 to 8 for the deposition of metallic thin films.

10. Use of the sputtering target according to any one of claims 1 to 8 for the deposition of high-temperature resistant thin films.

11. A process for producing a sputtering target comprising 0.3 to 10 wt.% of an oxygen-containing lanthanum compound (La), the remainder molybdenum (Mo) and unavoidable impurities, by powder metallurgy, characterized in that it comprises at least the following steps: Mixing molybdenum powder and an oxygen-containing lanthanum compound in powder form to form a powder mixture; Compacting the powder mixture by applying pressure, heat or pressure and heat to form a blank, characterized in that the sputtering target has a Mo phase and a La phase, wherein an average grain size of the Mo grains in the Mo phase is 1 to 200 pm and the sputtering target has an isotropic microstructure.

12. Method for producing a sputtering target according to claim 11, wherein the oxygen-containing lanthanum compound is obtained via calcination.

13. Method according to one of the preceding claims 11 and 12, wherein the compaction step is carried out by means of spark plasma sintering, hot pressing or hot isostatic pressing.

14. Method according to any one of the preceding claims 11 to 13, wherein the compression step is carried out at temperatures between 1000 and 1800°C.

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