Sputter target and method for producing a sputter target

Abstract

A target for use in a physical vapor deposition process includes a matrix composed of a composite material selected from the group consisting of aluminum-based material, titanium-based material and chromium-based material and all combinations thereof. The matrix is doped with doping elements and the doping elements are embedded as constituents of ceramic compounds or aluminum alloys in the matrix. The doping elements are selected from the group of the lanthanides: La, Ce, Nb, Sm and Eu. A process for producing such a target and a use of such a target in a physical vapor deposition process are also provided.

Claims

1. A target for a physical vapor deposition process, the target comprising: a matrix comprised of a composite material selected from the group consisting of aluminum-based material, titanium-based material, chromium-based material and all combinations of said materials; and doping elements doping said matrix, said doping elements being embedded as constituents of ceramic compounds in said matrix and said doping elements being selected from the group consisting of La, Ce, Nd, Sm and Eu, said doping elements being present in the target in a total concentration in a range from greater than or equal to 1 at % to less than or equal to 10 at %, said doping elements being homogeneously distributed in the target and configured to concentrate available impact energy of sputtering gas ions, and said elements of said matrix forming a proportion of greater than or equal to 60 at % and less than or equal to 99 at % of the target.

2. The target according to claim 1, wherein said doping elements are present in the target in a total concentration in a range from greater than or equal to 1 at % to less than or equal to 5 at %.

3. The target according to claim 1, wherein said matrix is present as aluminum-based material having a composition of Al.sub.xM.sub.1-x, where M is one or more elements from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Ta, W, Si and x is greater than 25 at %.

4. The target according to claim 1, wherein said matrix is present as titanium-based material having a composition of Ti.sub.xM.sub.1-x, where M is one or more elements from the group consisting of V, Cr, Zr, Nb, Mo, Ta, W, Si and x is greater than 50 at %.

5. The target according to claim 1, wherein said matrix is present as chromium-based material having a composition of Cr.sub.xM.sub.1-x, where M is one or more elements from the group consisting of Ti, V, Zr, Nb, Mo, Ta, W, Si and x is greater than 50 at %.

6. The target according to claim 1, which further comprises an oxygen content in the target of less than 5000 μg/g.

7. The target according to claim 1, which further comprises an oxygen content in the target of less than 3000 μg/g.

8. The target according to claim 1, wherein a proportion of elements having a work function of greater than or equal to 4.5 eV in the target is less than 10 at %.

9. The target according to claim 1, wherein said ceramic compounds are selected from the group consisting of at least one of borides or carbides or nitrides or silicides.

10. The target according to claim 1, wherein said doping element is cerium and is present as a ceramic compound formed of cerium disilicide.

11. The target according to claim 1, wherein said doping element is La and is present as a ceramic compound formed of lanthanum hexaboride.

12. A physical vapor deposition process, which comprises using the target according to claim 1 to carry out the vapor deposition process.

13. A target for a physical vapor deposition process, the target comprising: a matrix comprised of chromium-based material; and doping elements doping said matrix, said doping elements being embedded as constituents of ceramic compounds in said matrix and said doping elements being selected from the group consisting of La, Ce, Nd, Sm and Eu, said doping elements being homogeneously distributed in the target and being present in the target in a total concentration in a range from greater than or equal to 1 at % to less than or equal to 10 at %, said doping elements being homogeneously distributed in the target and configured to concentrate available energy, and said elements of said matrix forming a proportion of greater than or equal to 60 at % and less than or equal to 99 at % of the target.

14. The target according to claim 13, wherein said doping element is cerium and is present as a ceramic compound formed of cerium disilicide.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will be illustrated below with the aid of the figures.

(2) The figures show:

(3) FIG. 1 a graph of the coating rate (also known as deposition rate) as a function of the content of the doping elements Ce and La

(4) FIG. 2 an optical micrograph of a TiAlLaB6 target in cross section

(5) FIG. 3 an optical micrograph of a TiAlCe target in cross section

DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows the coating rate in nm/min as a function of the content y [at %] of the doping elements Ce and La for a TiAl, TiAlCe and TiAlLaB6 target. The coating rate was determined by means of SEM in the cross-sectional configuration for Ti.sub.1-xAl.sub.xN, Ti.sub.1-x-yAl.sub.xCe.sub.yN and Ti.sub.1-x-yAl.sub.x(LaB.sub.6).sub.yN layers.

(7) The coating rate for the undoped TiAl target corresponds to the point with 0 at % of doping element.

(8) The contents y of the doping elements Ce and La were determined in the deposited layer, and the empirical formula for the composition of the layer is
Ti.sub.1-x-yAl.sub.x(Ce/La).sub.yN.

(9) The determination of the concentrations of the elements in the layer was carried out by means of EDX.

(10) Targeted alloying of the target with from about 2 to 2.5 at % (Ce or LaB6) made it possible to achieve an increase in the sputtering rate from 50 to 80% for reactive sputtering (gas mixture: Ar/N.sub.2).

(11) As a word of explanation, it may be mentioned that the lanthanum is present as LaB6 in the target, but as elemental lanthanum, preferably on lattice sites of Ti or Al, in the layer deposited therefrom.

(12) FIG. 2 shows an optical micrograph of a TiAlLaB6 target in cross section. As indicated in the figure, the light-colored regions consist of aluminum, the gray regions consist of titanium and the black regions consist of LaB6 powder particles.

(13) FIG. 3 shows an optical micrograph of a TiAlCe target in cross section. As indicated in the figure, the light-colored regions consist of aluminum, the gray regions consist of titanium powder particles and the fine-grained dark gray agglomerates consist of a CeAl alloy. The black regions in the microstructure correspond to preparation-related cavities (grains broken out on polishing of the sample).

PRODUCTION EXAMPLES

Example 1

(14) For the powder-metallurgical manufacture of targets having the nominal composition of Ti/Al/LaB6 49.0/49.0/2.0 mol %, a powder batch of 800 g was produced by mixing 460.4 g of Ti powder, 259.5 g of Al powder and 80.0 g of LaB6 powder. These weights used correspond to the composition Ti/Al/LaB6 57.6/32.45/10.0 wt %. Based on the elements, this composition corresponds to Ti/Al/La/B 43.8/43.8/1.8/10.6 at %.

(15) The powder batch was subsequently forged at room temperature to give a compact and subsequently at 350° C. to give a blank. A target having the dimensions Ø75×6 mm was subsequently made from the blank by cutting machining. The nature of such a material is shown in FIG. 2 with the aid of an optical micrograph of a cross section of the material. The targets produced in this way, namely disks having the dimensions Ø75×6 mm, were subsequently bonded by means of indium onto copper cathodes of a laboratory coating plant (adapted Leybold Heraeus Z400) and installed in the plant. In a PVD process, the targets were atomized at a total pressure, p.sub.total, of 0.35 Pa in a gas mixture of Ar and N.sub.2 (20% of N.sub.2). The targets were operated at a power density of 9.0 W/cm.sup.2 for a time of 35 minutes. The resulting layers were deposited on single-crystal Si plates (100 orientation, 20×7×0.38 mm.sup.3) and on metallographically polished austenite plates (20×7×0.8 mm.sup.3). In order to be able to ensure satisfactory adhesion of the layers, the substrate materials were cleaned in acetone and ethanol before being thermally etched at 430±20° C. in the coating plant. After this thermal etching process, plasma etching was carried out in a pure Ar atmosphere at a total pressure of 6 Pa (duration 10 min). During the coating process, the substrate temperature was 430±20° C., and the bias potential was −50 V. The layers deposited in this way have a very dense morphology and a face-centered cubic crystal structure which was examined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The chemical composition was determined by means of energy-dispersive X-ray spectroscopy (EDX) in the SEM. In order to achieve a reduction in the La content in the deposited layer, pieces of TiAl (8 pieces having dimensions of 4×4×4 mm.sup.3 and a chemical composition of Ti/Al 50/50 at %) were placed in the racetrack. Despite a slight covering of the TiAlLaB6 target by the TiAl pieces (less than 10% of the racetrack), a clear increase in the coating rate could be detected—see FIG. 1. The thickness of the layers was about 3650 and 4800 nm, respectively (the 3650 nm were achieved for the layer having about 1.5 at % of La in the layer) for the respective La contents (FIG. 1). The mechanical properties of the Ti.sub.1-x-yAl.sub.xLa.sub.yN layers were tested by means of nanoindentation and displayed an increase compared to pure Ti.sub.1-xAl.sub.xN which was deposited under the same conditions.

Example 2

(16) For the powder-metallurgical manufacture of targets having the nominal composition of Ti/Al/Ce 49.0/49.0/2.0 mol %, a powder batch of 800 g was produced by mixing 475.3 g of Ti powder, 260.2 g of Al powder and 64.5 g of Ce/AI 88/12 wt % powder. These weights used correspond to the composition Ti/Al/CeAl 59.4/32.5/8.1 wt %.

(17) The powder batch was subsequently forged at room temperature to give a compact and subsequently at 350° C. to give a blank. A target having the dimensions Ø75×6 mm was subsequently made from the blank by cutting machining. The nature of such a material is shown in FIG. 3 with the aid of an optical micrograph of a cross section of the material. The targets produced in this way, having the dimensions Ø75×6 mm, were subsequently bonded by means of indium onto copper cathodes of a laboratory coating plant (adapted Leybold Heraeus Z400) and installed in the plant. In a PVD process, the targets were atomized at a total pressure, p.sub.total, of 0.35 Pa in a gas mixture of Ar and N.sub.2 (20% of N.sub.2). The targets were operated at a power density of 9.0 W/cm.sup.2 for a time of 45 minutes. The resulting layers were deposited on single-crystal Si plates (100 orientation, 20×7×0.38 mm.sup.3) and on metallographically polished austenite plates (20×7×0.8 mm.sup.3). In order to be able to ensure satisfactory adhesion of the layers, the substrate materials were cleaned in acetone and ethanol before being thermally etched at 430±20° C. in the coating plant. After this thermal etching process, plasma etching was carried out in a pure Ar atmosphere at a total pressure of 6 Pa (duration 10 min). During the coating process, the substrate temperature was 430±20° C., and the bias potential was −50 V. The layers deposited in this way have a very dense morphology and a face-centered cubic crystal structure which was examined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The chemical composition was determined by means of energy-dispersive X-ray spectroscopy (EDX) in the SEM. The layers had thicknesses of about 3600 and 5000 nm, respectively. These two different layer thicknesses were attained by placing, in order to reduce the Ce content, 8 TiAl pieces (4×4×4 mm.sup.3, chemical composition of Ti/Al 50/50 at %) in the racetrack and thus reducing the increase in the coating rate. Despite slight covering of the TiAlCe target by the TiAl pieces (less than 10% of the racetrack), an increase in the coating rate could be detected—see FIG. 1. The mechanical properties of the

(18) Ti.sub.1-x-yAl.sub.xCe.sub.yN layers were tested by means of nanoindentation and displayed a slight increase compared to pure Ti.sub.1-xAl.sub.xN which was deposited under the same conditions.

Example 3

(19) For the powder-metallurgical manufacture of targets having the nominal composition of Ti/Al/CeSi2, 39.4/60.6/2.1 mol %, a powder batch of 800 g was produced by mixing 383.2 g of Ti powder, 332.0 g of Al powder and 84.8 g of CeSi2 powder. These weights used correspond to the composition Ti/Al/CeSi2 47.9/41.5/10.6 wt %. Based on the elements, this composition corresponds to Ti/Al/Ce/Si 37.0/57.0/2.0/4.0 at %.

(20) The powder batch was subsequently forged at room temperature to give a compact and subsequently forged at 350° C. to give a blank. A target having the dimensions Ø75×6 mm was subsequently produced from the blank by cutting machining.