WO2023099757A1

WO2023099757A1 - A process for depositing a coating on a substrate by means of pvd methods and the coating obtained by said process

Info

Publication number: WO2023099757A1
Application number: PCT/EP2022/084267
Authority: WO
Inventors: Stéphane Lucas; Emile HAYE; Loris CHAVEE
Original assignee: Université De Namur
Priority date: 2021-12-03
Filing date: 2022-12-02
Publication date: 2023-06-08

Abstract

The process according to the invention is a process for depositing a coating on a substrate by means of physical vapor deposition methods, comprising a step of depositing said coating on said substrate by the simultaneous use of high-power impulse magnetron sputtering [hereafter, HIPIMS], and synchronous bipolar pulsed dual magnetron sputtering [hereafter, BPDMS]. The HIPIMS is applied to at least one sputtering target and BPDMS is applied to at least one pair of sputtering targets. Each sputtering target independently from each other comprises a metal composition, each metal composition independently from each other comprising, based on the total amount of atoms in said metal composition, at least 50 at. % of at least one metal selected from the group consisting of transition metals and post-transition metals..

Description

“A process for depositing a coating on a substrate by means of PVD methods and the coating obtained by said process”

FIELD OF THE INVENTION

The present invention relates a process for depositing a coating on a substrate by means of physical vapor deposition methods and the coating obtained by said process.

BACKGROUND OF THE INVENTION

For the last 60 years, physical vapor deposition (hereafter, PVD) methods have been used for applying coatings on a variety of substrates, for various application. For examples PVD methods can be applied to coat high speed and lubricant-free machining tools. Various PVD method exists, such as arc vapor deposition, thermal evaporation or magnetron sputtering. Magnetron sputtering is based on the sputtering of a target (the solid material source) by ions, in a vacuum chamber. Thanks to the application of a negative electrical potential to the target, in the presence of low pressure environment, ions are formed (plasma), and are attracted to the targets, leading to its sputtering. The sputtered species are then condensed on all the surfaces in front of the target. A substrate to be coated it thus set in this area.

Among magnetron sputtering, several processes exist, such as direct current sputtering (hereafter, DCMS), high power impulse magnetron sputtering (hereafter, HIPIMS), and bipolar pulsed dual magnetron sputtering (hereafter, BPDMS), which are characterized by the way of the current is applied to the target(s). In DCMS a continuous and negative current is applied, while HiPIMS is a pulsed discharge with high amplitude and short duty cycle. BPDMS is a particular case where two targets are sputtered with synchronous and opposite potential. Hybrid processes, namely the combination of at least two of the aforementioned methodology has some benefits. In this view, the document EP 2565291 A1 discloses a method of manufacturing a coating on a substrate in a vacuum chamber having at least one pair of opposed cathodes and at least one further cathode, which are operated simultaneously. The pair of opposing cathodes are connected to an alternative current (hereafter, AC) power supply and are operated in a dual magnetron sputtering mode, while the at least one further cathode is a magnetron cathode or arc cathode. In a preferred embodiment, in addition to the pair of opposing cathodes, two further magnetron cathodes connected to HIPIMS power supplies, are provided.

However, the processes for depositing a coating on a substrate by means of physical vapor deposition methods of the prior art suffer from several disadvantages such as low deposition rate and/or low coating hardness. Moreover, the coatings obtained by these methods often have insufficient hardness and density.

For these reasons, there is a continuous need to provide improved processes for depositing a coating on a substrate by means of physical vapor deposition methods. In particular, there is a need to provide a process for depositing a coating on a substrate by means of physical vapor deposition methods having high deposition rate and enabling to obtain a coating having high hardness.

SUMMARY OF THE INVENTION

The inventors have found that the aforementioned problems can be solved by the process according to the invention. The process according to the invention is a process for depositing a coating on a substrate by means of physical vapor deposition methods, comprising a step of depositing said coating on said substrate by the simultaneous use of

- high-power impulse magnetron sputtering [hereafter, HIPIMS], and

- synchronous bipolar pulsed dual magnetron sputtering [hereafter, BPDMS], wherein HIPIMS is applied to at least one sputtering target and BPDMS is applied to at least one pair of sputtering targets, and wherein each sputtering target independently from each other comprises a metal composition, each metal composition independently from each other comprising, based on the total amount of atoms in said metal composition, at least 50 at. % of at least one metal selected from the group consisting of transition metals and post-transition metals.

The invention also concerns a coating and a coating obtained by the process according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

- high-power impulse magnetron sputtering [hereafter, HIPIMS], and

- synchronous bipolar pulsed dual magnetron sputtering [hereafter, BPDMS].

The inventors have surprisingly found that the combination of HIPIMS with BPDMS enables to reach high deposition rates and to obtain a coating having high hardness and density. The process according to the present invention also has the advantage to provide coatings having a high thermal stability and can easily be removed if desired

Within the context of the present invention, the term “comprising” should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements. It needs to be interpreted as specifying the presence of the stated features, integers, or components as referred to, but does not preclude the presence or addition of one or more other features, integers, or components, or groups thereof. Thus, the scope of the expression “a composition comprising compounds A and B” should not be limited to compositions consisting only of compounds A and B. It means that with respect to the present invention, the only relevant compounds of the composition are A and B. Accordingly, the terms “comprising” and “including” encompass the more restrictive terms “consisting essentially of” and “consisting of”.

The term “high deposition rates” is given its normal meaning in the field by the skilled in the art. In particular it is intended to denote a deposition rate which is higher than if the same coating was deposited by HiPIMS magnetron sputtering in the same conditions with the same apparatus, preferably by a least 10%, most preferably at least 20% and even more preferably by at least 30%. The deposition rate can be measured by determining the thickness of the coating by microscopy or by profilometry and by dividing said thickness by the deposition time. To allow for an optimal comparison, it is necessary to normalize the deposition rate by considering the total power applied to the targets (for example: 2500W on a target of TiAITa composition, operating in HiPIMS alone, compared to 2800 + 750 + 76 W distributed over 3 targets). As a consequence, the deposition is expressed as nm I (s.W).

Within the context of the present invention, the phrase “a coating having high hardness” is intended to denote a coating having a hardness of at least 25 GPa, preferably at least 30 GPa, more preferably at least 35 GPa, as measured by method nanoindentation test based on norm ISO 14577.

Within the context of the present invention, the phrase “a coating having high thermal stability” is intended to denote a coating that can sustain a temperature of at least 700°C in air during 1 h, more preferably a temperature of at least 800°C in air during 1 h, even more preferably a temperature of at least 900°C in air during 1 h without exhibiting substantial deterioration. The acronym HIPIMS refers to high-power impulse magnetron sputtering which is a well-known specific PVD method. Thus, HIPIMS is given its usual meaning by the skilled in the art.

In particular, in a HIPIMS process, electrical power is supplied to a target in a series of very short, powerful pulses with low duty cycle. During the resulting discharge, high current densities are reached at the targets. During a HIPIMS process, a long off time (Toff) and a very short on time (Ton) are used, in order to maintain a relatively low average current density, defined in A/cm², corresponding to the current in Amps divided by the target surface in cm². In a typical HIPIMS process, the Toff is at least one order of magnitude longer than the Ton. In a typical HIPIMS process, the Ton varies between 10 ps and 100 ps while the Toff varies between 500 ps and 2500 ps.

In the context of the present invention, Toff and Ton, are given their usual meaning by the skilled in the art. In particular, in a given pulse, Ton is the time during which the absolute value of the voltage or the power is at its maximum while Toff, is the time during which the value of the voltage or the power is equal to 0. More particularly, during the Ton, the absolute value of the voltage is maintained at a constant value.

The acronym BPDMS refers to bipolar pulse dual magnetron sputtering which is a well-known specific PVD method. Thus, BPDMS is given its usual meaning by the skilled in the art.

In particular, in a BPDMS process, electrical power is supplied to a at least one pair of sputtering sources, each provided with a sputtering target, in a series of pulses. Each sputtering source receives alternatively positive voltage pulses and negative voltage pulses, with an off time (voltage null) between each pulse. When one sputtering source of one pair of sputtering sources receives a positive voltage pulse, the other sputtering source receives a negative voltage pulse at the exact same time, hence the term “synchronous”. As a result, in a BPDMS process, each sputtering source acts alternatively as a cathode and then as an anode, hence the term “bipolar”. Each of the positive and negative pulses are of equal amplitude and duration, thus, the positive and the negative pulse can be characterized by a single Ton and Toff which are usually of the same order of magnitude and vary between 50 ps and 400 ps. As a consequence of the presence of a Ton and a Toff, the form of the signal of the applied voltage pulse is preferably rectangular. In other words, the form of the signal of the applied voltage pulse is not sinusoidal.

In other words, since each sputtering source is provided with a sputtering target, what applies to sputtering sources applies, also applies to sputtering targets. Therefore, in the context of the present invention, the term “synchronous” intends to denote that when one sputtering target of one pair of sputtering targets receives a positive or a negative voltage pulse, the other sputtering source receives a voltage pulse of opposite polarity at the exact same time during the same duration (same Ton).

In the process according to the present invention, HIPIMS is applied to at least one sputtering target and BPDMS is applied to at least one pair of sputtering targets.

Preferably, HIPIMS is applied to said at least one sputtering target in the form of a series of electrical power pulses [hereafter, “HIPIMS pulses”].

Preferably said series of HIPIMS pulses has a Ton of at least 10 ps, preferably at least 30 ps, more preferably at least 40 ps. Preferably said series of HIPIMS pulses has a Ton of at most 500 ps, preferably at most 200 ps, more preferably at most 100 ps.

In a preferred embodiment, said series of HIPIMS pulses has a Ton of at least 10 and at most 100, preferably a Ton of at least 30 ps and at most 80 ps, more preferably a Ton of at least 40 ps at most 60 ps.

Preferably, said series of HIPIMS pulses has a Toff of at least 1000 ps, preferably at least 1500 ps, more preferably at least 1800 ps. Preferably said series of electrical power pulses has a Toff of at most 2500 ps, preferably at most 2300 ps, more preferably at most 2000 ps.

Preferably said series of HIPIMS pulses has a Toff of at least 1000 ps and at most 2500 ps, preferably a Toff of at least 1500 ps and at most 2300 ps, more preferably a Toff of at least 1800 ps and at most 2000 ps.

Preferably, each of said HIPIMS pulses has an intensity which is constant all along the Ton.

Preferably, each of said HIPIMS pulses has an intensity of at least 500 V, more preferably of at least 600 V, even more preferably at least 650 V.

Preferably, each of said HIPIMS pulses has an intensity of at most 1200 V, more preferably of at most 1000 V, even more preferably at most 900 V.

In a preferred embodiment, each of said HIPIMS pulses has an intensity of at least 500 V and at most 1200 V, preferably of at least 600 V and at most 1000 V, even more preferably at least 650 V and at most 900 V.

In particular, during said series of HIPIMS pulses, the corresponding current density rises during the Ton to its maximum value (Cpeak), also called peak current density. During said series of HIPIMS pulses, the peak current density is preferably of least 0.2A/cm², more preferably of at least 0.6 A/cm². During said series of HIPIMS pulses, the peak current density is preferably of at most 5 A/cm².

Preferably, BPDMS is applied to said at least one pair of sputtering targets in the form of a series of synchronous electrical power pulses [hereafter, “BPDMS pulses”].

. Preferably, said series of BPDMS pulses has a Ton of at least 50 ps, preferably at least 100 ps, more preferably at least 250 ps. Preferably, said series of BPDMS pulses has a Ton of at most 400 ps, preferably at most 350 ps, more preferably at most 300 ps. In a preferred embodiment, said series of BPDMS pulses has a Ton of at least 50 ps and at most 400 ps, preferably a Ton of at least 100 ps and at most 350 ps, more preferably a Ton of at least 250 ps at most 300 ps.

Preferably, said series of BPDMS pulses has a Toff of at least 50 ps, preferably at least 70 ps, more preferably at least 90 ps. Preferably, said series of BPDMS pulses has a Toff of at most 400 ps, preferably at most 350 ps, more preferably at most 150 ps.

In a preferred embodiment, said series of BPDMS pulses has a Toff of at least 50 ps and at most 400 ps, preferably a Toff of at least 70 ps and at most 350 ps, more preferably a Toff of at least 90 ps and at most 150 ps.

Preferably, each of the BPDMS pulses is applied by a DC voltage.

Preferably, each of said BPDMS pulses has an intensity of at least 100 V and at most 1100 V, preferably of at least 200 V and at most 900 V, even more preferably at least 300 V and at most 800 V.

Preferably, the targets of said pair of sputtering targets are angularly spaced around a rotation axis (A) by an angle (0) comprised between 120° and 30°, more preferably with an angle comprised between 60° and 45°, even more preferably with an angle of 60°. Alternatively, each of said targets has a first surface and said angle (0) is an angle formed by a first centered normal axis to said first surface of a first target of said pair of sputtering targets and a second centered normal axis to a first surface of a second target of said pair of sputtering targets. The first centered normal axis 3 passes through the geometric center of the first surface of the first target 2 and the second centered normal axis 3’ passes through the geometric center of the first surface of the second target 2’. Preferably, said targets of said pair of sputtering targets are the same. The first surface of each target is a sputtering surface. Within the context of the present invention, a sputtering surface is the surface of a target facing said substrate or the surface from which the target sputtering occurs during the process according to the present invention.

This configuration limits/suppresses the electronic bombardment to the benefit of the ionic bombardment of the substrate.

According to the present invention, each sputtering target independently from each other comprises a metal composition, each metal composition independently from each other comprising, based on the total amount of atoms in said metal composition, at least 50 at.% of at least one metal selected from the group consisting of transition metals and post-transition metals.

Preferably said at least one metal is selected from the group consisting of Ti, Al, Ta, Cr, V, Nb, Hf, W and Zr.

Preferably, said at least one sputtering target to which HIPIMS is applied is made of at least one metal selected from the group consisting of transition metals and post-transition metals. More preferably, said at least one target to which HIPIMS is applied, is made of at least one metal selected from the group consisting of Ta, Hf, W, Zr.

Preferably, each sputtering target of said at least one pair of sputtering targets to which BPDMS is applied is made of at least one metal selected from the group consisting of transition metals and post-transition metals. More preferably, each sputtering target of said at least one pair of sputtering targets to which BPDMS is applied is made of at least one metal selected from the group consisting of Ta, Ti, Al, Cr, V, Nb.

Preferably, the process according to the present invention comprises the application of a voltage bias on the substrate to be coated of at least 50 V, more preferably at least 100 V.

More preferably, the process according to the present invention comprises the application of a voltage bias of at most 250 V, more preferably at most 200 V, more preferably at most 160 V. More preferably, the process according to the present invention comprises the application of a voltage bias of at least 50 V and at most 250 V, more preferably at least 100 V and at most 200 V, more preferably of 150 V.

In particular, said substrate and all the sputtering targets are placed inside a vacuum chamber. More particularly, said vacuum chamber also comprises an Ar/N2 gas mixture. Even more particularly, the Ar/N2 gas pressure inside the vacuum chamber is comprised between 266 Pa and 2000 Pa, preferably between 266 Pa and 1333 Pa, more preferably between 400 Pa and 933 Pa.

The present invention also concerns a coating obtained by the process according to the present invention.

The present invention also concerns a coating comprising at least one layer comprising based on the total amounts of atoms in said at least one layer:

• at least 2 at. % and at most 40 at. % of a first metal and

• at least 10 to 40 at. % of a second metal and

• at least 10 to 40 at. % of a third metal, and

• at least 45 at. % and at most 65 at. % of N, said first metal and second metal and third metal being in the form of metal nitride.

Preferably, said first metal is selected from the group consisting of Ti, Al, Cr, Si, V, Zr, Nb, Hf, Ta, W. In particular, said first metal comes from said at least one sputtering target to which HIPIMS is applied.

Preferably, said second metal is selected from the group consisting of Ti, Al, Cr, Si, V, Zr, Nb, Hf, Ta, W.

Preferably, said third metal is selected from the group consisting of Ti, Al, Cr, Si, V, Zr, Nb, Hf, Ta, W.

In particular, said second and third metal comes from said at least one pair of sputtering targets to which BPDMS is applied. Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 4 at. %, more preferably at least 6 at. % even more preferably at least 8 at. % of said first metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at most 30 at. %, more preferably at most 20 at. % even more preferably at most 10 at. % of said first metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 4 at. % and at most 30 at. %, more preferably at least 6 at. % and at most 20 at. % even more preferably at least 8 at. % and at most 10 at. % of said first metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 12 at. %, more preferably at least 15 at. % even more preferably at least 20 at. % of said second metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at most 35 at. %, more preferably at most 30 at. % even more preferably at most 25 at. % of said second metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 12 at. % and at most 35 at. %, more preferably at least 15 at. % and at most 30 at. % even more preferably at least 20 at. % and at most 25 at. % of said second metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 12 at. %, more preferably at least 15 at. % even more preferably at least 20 at. % of said third metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at most 35 at. %, more preferably at most 30 at. % even more preferably at most 25 at. % of said third metal.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 12 at. % and at most 35 at. %, more preferably at least 15 at. % and at most 30 at. % even more preferably at least 20 at. % and at most 25 at. % of said third metal. Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 43 at. %, more preferably at least 45 at. % even more preferably at least 50 at. % of N.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at most 60 at. %, more preferably at most 57 at. % even more preferably at most 55 at. % of N.

Preferably, said layer comprises based on the total amounts of atoms in said at least one layer at least 43 at. % and at most 60 at. %, more preferably at least 45 at. % and at most 57 at. % even more preferably at least 50 at. % and at most 55 at. % of N.

It is understood that within the context of the present invention the atomic percentages of said first, second and third metals, and the atomic percentages nitrogen as mentioned above and in the claims are measured by X-ray photoelectron spectroscopy (XPS). Preferably, said coating according to the present invention are profiled using a monoatomic Ar⁺ beam working at 2 keV and 10 pA, on a K-Alpha Thermo Scientific spectrometer (Al Ka radiation 1486.68 eV) with a spot size of 250x250 pm, and raster size of 1.25x1 .25mm. To generate the profile, ten snapshot of Cr 2p, N 1 s, O 1 s, C 1 s and Si 2p levels have been recorded after every etch step (8 s, approximately 2 nm), at a pass energy of 150 eV. Then, the concentration of each species is derived from the spectrum area of the scan, after subtraction of a Shirley background. The concentration is constant all along the depth of the coating.

Preferably, said coating has a thickness of at least 10 nm, preferably at least 1 pm. More preferably, said coating has a thickness of at most 10 pm, even more preferably at most 5 pm, even more preferably at most 3 pm. The present invention also concerns an article comprising a support covered by said coating according to the present invention and an adhesive layer between said support and said coating.

Preferably said adhesive layer is made of Ti or Al, or Ta or combinations thereof. More preferably said adhesive layer is made of TiAl or Ta or TiAITa.

It has been observed that the coating according to the present invention have a hardness of at least 25 GPa, preferably at least 30 GPa, more preferably at least 35 GPa, as measured by nanoindentation test according to norm ISO 14577.

Example 1

A coating was deposited on a substrate by means of PVD methods via the simultaneous use of HIPIMS and BPDMS.

HIPIMS was used for sputtering a first target of Ta while BPDMS was used for sputtering a pair of targets of TisoAho.

Figure 1 illustrates targets and substrate configuration used in the example 1 . In this embodiment, the targets of the pair of targets 2 and 2’ comprised in the vacuum chamber 1 are angularly spaced around a rotation axis A by an angle 0 of 60°. The angle 0 also corresponds to an angle formed by a first centered normal axis 3 to the sputtering surface of the first target 2 of said pair of sputtering targets 2 and 2’ and a second centered normal axis 3’ to the sputtering surface of the second target 2’ of said pair of sputtering targets 2 and 2’. The first centered normal axis 3 passes through the geometric center of the sputtering surface of the first target 2 and the second centered normal axis 3’ passes through the geometric center of the sputtering surface of the second target 2’. Both centered normal axes 3 and 3’ cross said axis A.

The substrate and all the targets were place inside a vacuum chamber comprising an Ar/N2 gas mixture with a pressure of 5mT. A negative bias voltage of 150 V was applied on the substrate. No heating was applied.

Electrical power was supplied to a cathode provided with the Ta sputtering target in a series of very short, powerful pulses with low duty cycle according to the HIPIMS process having the characteristics listed in table 1 below.

Table 1

Electrical power is supplied to the pair of TisoAho sputtering targets as a pulsed electrical power according to BPDMS. The BPDMS process had the characteristics listed in table 2 below.

Table 2

The HIPIMS and the BPDMS processes were applied simultaneously for a duration of 4h.

This process duration time is quite low, indicating a surprisingly high deposition rate of 1 .99.10⁵ nm/(s.W).

The obtained coating had the characteristics listed in table 3 below. Table 3

The coating comprised a substrate which was itself covered by an adhesive layer of TiAITa. The adhesive layer was itself covered by a coating layer which had the characteristics shown in table 3. The atomic percentages shown in table 3 are calculated with regards to the total amount of atoms in the coating layer by XPS, more specifically with method of depth profiling described previously. The hardness was measured as described previously (nanoindentation test in following ISO 14577). The thickness was determined with tactile profilometry or electron microscope observation, both methods giving the same results.

The adhesive layer of TiAITa was applied on the substrate before application of the coating by the process according to the present invention. The process conditions for applying the adhesive layer of TiAITa were the same as the conditions for applying the coating as explained above, with the exception that the vacuum chamber contained only Ar gas and no nitrogen.

The coating was easily removable by chemical attack. Depending on the substrate (high speed steel, stainless steel, carbide), the coating can be peeled off using chemical attack based on alkaline product, that need to be compatible with the substrate.

Comparative example 1

A coating was deposited on a substrate by means of PVD methods via the use of HIPIMS. HIPIMS was used for sputtering a first target of Ta and a pair of targets of TisoAho.

Electrical power was supplied to a cathode provided with the sputtering targets in a series of very short, powerful pulses with low duty cycle according to the HIPIMS process having the characteristics listed in table 4 below.

Table 4

The obtained coating had the characteristics listed in table 5 below.

Table 5

The coating comprised a substrate which was itself covered by an adhesive layer of TiAITa as in example 1. The adhesive layer was itself covered by a coating layer which had the same characteristics as in example 1 .

The adhesive layer of TiAITa was applied on the substrate before application of the coating by the process according to the present invention by HIPIMS exactly in the same conditions as specified in table

4, with the exception that the vacuum chamber contained only Ar gas and no nitrogen.

The deposition rate was of 1 .34.10^-5 nm/(s.W) which is 35 % slower than in example the deposition rate of the process according to example 1 .

Claims

1 . A process for depositing a coating on a substrate by means of physical vapor deposition methods, comprising a step of depositing said coating on said substrate by the simultaneous use of

- high-power impulse magnetron sputtering [hereafter, HIPIMS], and

- synchronous bipolar pulsed dual magnetron sputtering [hereafter, BPDMS], wherein HIPIMS is applied to at least one sputtering target and BPDMS is applied to at least one pair of sputtering targets in the form of a series of synchronous voltage pulses [hereafter, BPDMS pulses] having a Toff of at least 50 ps and at most 400 ps and a Ton of at least 50 ps and at most 400 ps, and wherein each sputtering target independently from each other comprises a metal composition, each metal composition independently from each other comprising, based on the total amount of atoms in said metal composition, at least 50 at.% of at least one metal selected from the group consisting of transition metals and post-transition metals.

2. A process according to claim 1 , wherein HIPIMS is applied to said at least one sputtering target in the form of a series of electrical power pulses [hereafter, HIPIMS pulses].

3. A process according to claim 2, wherein said series of HIPIMS pulses has a Ton of at least 10 and at most 100, preferably a Ton of at least 30 ps and at most 80 ps, more preferably a Ton of at least 40 ps at most 60 ps.

4. A process according to claim 2 or 3, wherein said series of HIPIMS pulses has a Toff of at least 1000 ps and at most 2500 ps, preferably a Toff of at least 1500 ps and at most 2300 ps, more preferably a Toff of at least 1800 ps and at most 2000 ps.

5. A process according to any one of claims 2 to 4, wherein each of said HIPIMS pulses has an intensity which is constant all along the Ton.

6. A process according to any one of claims 2 to 5, wherein each of said HIPIMS pulses has an intensity of at least 500 V and at most 1200 V, preferably of at least 600 V and at most 1000 V, even more preferably at least 650 V and at most 900 V.

7. A process according to claim 1 , wherein said series of BPDMS pulses has a Ton of at least 100 ps and at most 350 ps, more preferably a Ton of at least 250 ps at most 300 ps.

8. A process according to claim 1 , wherein said series of BPDMS pulses has a Toff of at least 70 ps and at most 350 ps, more preferably a Toff of at least 90 ps and at most 150 ps.

9. A process according to any one of the preceding claims, wherein said at least one metal is selected from the group consisting of Ti, Al, Ta, Cr, V, Nb, Hf, W and Zr and combinations thereof.

10. A process according to any one of the preceding claims, wherein said at least one target to which HIPIMS is applied, is made of at least one metal selected from the group consisting of Ta, Hf, W, Zr.

1 1. A process according to any one of the preceding claims, wherein each sputtering target of said at least one pair of sputtering target to which BPDMS is applied is made of at least one metal selected from the group consisting of Ta, Ti, Al, Cr, V, Nb.

12. A process according to any one of the preceding claims, comprising the application of a voltage bias of at least 50 V and at most 250 V, more preferably at least 100 V and at most 200 V, more preferably of 150 V.

13. A process according to any one of the preceding claims, wherein the targets of said pair of sputtering targets are angularly spaced around a rotation axis (A) by an angle (6) comprised between 120° and 30°, more preferably with an angle comprised between 60° and 45°, even more preferably with an angle of 60°.

14. A process according to any one of the preceding claims, wherein each of said BPDMS pulses has an intensity of at least 100 V and at most 1100 V, preferably of at least 200 V and at most 900 V, even more preferably at least 300 V and at most 800 V.

15. A coating obtained by the process according to any one of claims 1 to 14.