Cubic Al-rich AlTiN Coatings Deposited from Ceramic Targets

Abstract

The present invention discloses a non-reactive PVD coating process for producing an aluminium-rich Al.sub.xTi.sub.1−xN-based thin film having an aluminium content of >75 at-% based on the total amount of aluminium and titanium in the thin film, a cubic crystal structure, and a columnar microstructure, wherein ceramic targets are used as a material source for the aluminium-rich Al.sub.xTi.sub.1−xN-based thin film.

Claims

1-18. (canceled)

19. A non-reactive PVD coating process for producing an aluminium-rich Al.sub.xTi.sub.1−xN-based thin film having an aluminium content of >75 at-% based on the total amount of aluminium and titanium in the thin film, a cubic crystal structure, and a columnar microstructure, wherein ceramic targets are used as a material source for the aluminium-rich Al.sub.xTi.sub.1−xN-based thin film.

20. The coating process according to claim 19, wherein the ceramic targets being formed in the form of at least nitrides or oxides or carbides.

21. The coating process according to claim 19, wherein a negative bias voltage is applied to the substrate to be coated, wherein the bias voltage applied to the substrate is <120 V.

22. The coating process according to claim 19, wherein the ceramic targets comprise Al and Ti, wherein the aluminium content, based on the total amount of aluminium and titanium in the targets is higher than 50 at-%.

23. The coating process according to claim 19, wherein the coating is carried out without using a reactive gas.

24. The coating process according to claim 19, wherein AlN.sub.80TiN.sub.20 is used as target material for the aluminium-rich Al.sub.xTi.sub.1−xN-based thin film.

25. The coating process according to claim 19, wherein a sputtering technique is used as a non-reactive PVD coating process.

26. The coating process according to claim 25, wherein at least an HiPIMS or an ARC PVD coating process is used as a non-reactive PVD coating process.

27. The coating process according to claim 22, wherein the ceramic targets comprise also other elements apart from Al and Ti.

28. The coating process according to claim 27, wherein the ceramic targets comprise further transition metals.

29. The coating process according to claim 19, wherein a plurality of aluminium-rich Al.sub.xTi.sub.1−xN-based thin films are deposited one above the other to produce a multilayer thin film.

30. The coating process according to claim 19, wherein the substrate temperature is between 100° C. and 350° C.

31. An aluminium-rich Al.sub.xTi.sub.1−xN-based thin film having an aluminium content of >75 at-% based on the total amount of aluminium and titanium in the thin film, a cubic crystal structure and a columnar microstructure, producible by a non-reactive PVD coating process for producing an aluminium-rich Al.sub.xTi.sub.1−xN based thin film having an aluminium content of >75 at-% based on the total amount of aluminium and titanium in the thin film, a cubic crystal structure, and a columnar microstructure, wherein ceramic targets are used as a material source for the aluminium-rich Al.sub.xTi.sub.1−xN based thin film.

32. The aluminium-rich Al.sub.xTi.sub.1−xN-based thin film according to claim 31, wherein the layer thickness is >200 nm.

33. The aluminium-rich Al.sub.xTi.sub.1−xN-based thin film according to claim 31, wherein the thin film has a surface roughness R.sub.z of <0.8 μm.

34. The aluminium-rich Al.sub.xTi.sub.1−xN-based thin film according to claim 31, wherein the cubic structure comprises crystallite grains with an average grain size of more than 15 nm.

35. The aluminium-rich Al.sub.xTi.sub.1−xN-based thin film according to claim 31, wherein the thin film has an aluminium content of >76 at-% based on the total amount of aluminium and titanium in the thin film.

36. The aluminium-rich Al.sub.xTi.sub.1−xN-based thin film according to claim 31, wherein the thin film comprises other metallic elements in addition to aluminium and titanium.

37. The aluminium-rich Al.sub.xTi.sub.1−xN-based thin film according to claim 31, wherein the thin film is formed in the form of a multilayer layer structure comprising at least two aluminium-rich Al.sub.xTi.sub.1−xN-based thin films deposited on each other.

38. A use of an aluminium-rich Al.sub.xTi.sub.1−xN-based thin film having an aluminium content of >75 at-% based on the total amount of aluminium and titanium in the thin film, a cubic crystal structure and a columnar microstructure, producible by a non-reactive PVD coating process for producing an aluminium-rich Al.sub.xTi.sub.1−xN based thin film having an aluminium content of >75 at-% based on the total amount of aluminium and titanium in the thin film, a cubic crystal structure, and a columnar microstructure, wherein ceramic targets are used as a material source for the aluminium-rich Al.sub.xTi.sub.1−xN based thin film for manufacturing a tool.

Description

DETAILED DESCRIPTION

[0036] FIG. 1 shows a schematic illustration of the fraction of w-AlN, N.sub.2 consumption (growth rate/unit time) variation as a function of N.sub.2 partial pressure (a) and an XRD spectrum at different N.sub.2 partial pressures (b),

[0037] FIG. 2 shows a schematic illustration of the fraction of w-AlN as a function of substrate bias voltage (a) and an XRD spectrum of AlTiN coatings synthesized from Al.sub.80Ti.sub.20 target at different substrate bias (b),

[0038] FIG. 3 shows a schematic drawing of a combinatorial deposition set-up used to grow films from the ceramic targets,

[0039] FIG. 4 shows an optical photograph and SEM micrograph of ceramic targets of TiNAlN,

[0040] FIG. 5.1 shows films grown with combinatorial approach using ceramic targets,

[0041] FIG. 5.2 shows films grown with combinatorial approach using ceramic targets,

[0042] FIG. 5.3 shows films grown using ceramic targets,

[0043] FIG. 6 shows films grown with metallic and ceramic targets,

[0044] FIG. 7 shows films grown using AlN.sub.77TiN.sub.23 targets.

[0045] The following figures are intended to be helpfully for understanding the present invention but not for limiting the present invention:

[0046] FIG. 1 shows the influence of N.sub.2 partial pressure on structural evolution of AlTiN coatings synthesized from Al.sub.80Ti.sub.20 metallic target at substrate temperature of 200° C. and Ar partial pressure of 0.2 Pa. (a) Fraction of w-AlN, N.sub.2 consumption (growth rate/unit time) variation as a function of N.sub.2 partial pressure. Annoted text indicate partial pressure of reactive gas corresponding to metallic, transition and compound sputtering mode. (b) XRD spectrum at different N.sub.2 partial pressures of 0.09, 0.11, 0.13, and 0.15 Pa and corresponds to 1, 2, 3, and 4 consecutively.

[0047] FIG. 2 shows the influence of substrate bias on structural evolution of AlTiN alloy using metallic target. (a) fraction of w-AlN as a function of substrate bias voltage. Data extracted from xrd spectrum (F w-AlN: Intensity of wurtzite phase/Σ (intensity of cubic phase+intensity of wurtzite phase). (b) XRD spectrum of AlTiN coatings synthesized from Al80Ti20 target at different substrate bias of 80 V, 120 V, and 200 V.

[0048] FIG. 3 shows a schematic drawing of a combinatorial deposition set-up used to grow films from the ceramic targets.

[0049] FIG. 4 shows an optical photograph and SEM micrograph of ceramic targets of TiNAlN, as received and after 6 depositions. Note that TiN.sub.50AlN.sub.50 target shows cracks, and TiN.sub.20AlN.sub.80 does not show such cracks after several process repetitions.

[0050] FIG. 5.1 shows films grown with combinatorial approach using ceramic targets. (a) Batch parameters, (b) Composition of the films at different position of the substrate holder, and (c) X-SEM micro graph and XRD plot. Annotations: S.fwdarw.Substrate peaks, C.fwdarw.Cubic peak, W.fwdarw.Wurtzite phase. As shown in FIG. 5.1 the following coating parameter have been used: power density: 1 kW/cm.sup.2, pulse time: 5 ms, nitrogen partial pressure: 0 Pa (which corresponds to a nitrogen gas flow of 0 sccm) and argon gas flow: 40 sccm.

[0051] FIG. 5.2 shows films grown with combinatorial approach using ceramic targets. (a) Batch parameters, (b) Composition of the films at different position of the substrate holder, and (c) X-SEM micro graph and XRD plot. Annotations: S.fwdarw.Substrate peaks, C.fwdarw.Cubic peak, W.fwdarw.Wurtzite phase. As shown in FIG. 5.2 the following coating parameter have been used: power density: 1 kW/cm.sup.2, pulse time: 5 ms, nitrogen partial pressure: 0 Pa (nitrogen gas flow: 0 sccm) and argon gas flow: 300 sccm.

[0052] FIG. 5.3 shows films grown using ceramic targets. (a) Batch parameters, (b) Composition of the films at different position of the substrate holder, and (c) X-SEM micro graph and XRD plot. Annotations: S.fwdarw.Substrate peaks, C.fwdarw.Cubic peak, W.fwdarw.Wurtzite phase. As shown in FIG. 5.3 the following coating parameter have been used: power density: 1 kW/cm.sup.2, pulse time: 5 ms, nitrogen partial pressure: 0 Pa (nitrogen gas flow: 0 sccm) and argon partial pressure: 60 Pa.

[0053] In the examples given in FIGS. 5.1, 5.2 and 5.3, the substrates to be coated were hold by using fixture systems placed in a coating machine of the type Ingenia S3p manufactured by Oerlikon Balzers. For these examples fixture systems comprising two kinds of rotatable fixture components were used. A first kind of rotatable fixture component called carrousel was placed in known manner in the middle of the coating chamber for producing a first rotation. On the carrousel, a second kind of rotatable fixture components were placed also in known manner for causing a second rotation. The substrates to be coated were hold in the second kind of rotatable fixture components. The rotation speed of the carrousel was 30 seconds pro rotation, as it is indicated in the respective FIGS. 5.1, 5.2 and 5.3. However, the kind of coating machine and fixture system being used should not be understood as a limitation of the present invention. Likewise, the coating parameters used for the examples shown in FIGS. 5.1, 5.2 and 5.3 should not be understood as a limitation of the present invention.

[0054] FIG. 6 shows films grown with metallic, and ceramic targets at three different conditions. As shown in FIG. 6 the used conditions of the approach in the upper row were: a mixture of 0.1 Pa Ar- and 0.04 Pa N-pressure, temperature of 200° C. and a voltage of 150 V. However, the used conditions of the approach in the middle row were: Ar gas-flow for 60 s, temperature of 300° C. and a voltage of 150 V. The used conditions of the approach in the lower row were: Ar gas-flow for 40 s, temperature of 300° C. and a voltage of 80 V. Note that with ceramic targets, cubic phase can be achieved up to Al conc. of 78 at. % using only 80 V bias. For metallic targets, a high bias of above 120 V is desired to grow cubic phase.

[0055] Micrographs from left to right: Bottom, middle, and top of the chamber.

[0056] Based on the above examples and combinatorial design experiments, a ceramic target with 77 at. % Al was chosen to test the homogeneity of the cubic phase growth along the carousel length.

[0057] An additional feature of the coatings grown in this method is a relatively low surface roughness with a value Ra 0.03±0.01 μm and Rz 0.6±0.01 μm. FIG. 7 below shows the coating surface (a) before and after (b) calo-grinding, and (c) measured profiles of the coatings grown using the inventive method.