ITBO20110669A1 - METHOD FOR THE DEPOSITION OF A LAYER OF A MATERIAL ON A SUBSTRATE - Google Patents

Description

DESCRIPTION

â € œMETHOD FOR THE DEPOSITION OF A LAYER OF A MATERIAL ON A SUBSTRATEâ €

TECHNICAL FIELD

The present invention relates to a method for depositing a material on a substrate.

BACKGROUND OF THE INVENTION

Thin layers of zirconia (ZrO2) are currently used in the field of medical prostheses for their characteristics of hardness and biofampatibility and in the field of fuel cells. In particular, thin layers of zirconia are used to cover prostheses of other materials.

It is also known the use of zirconia alone or in combination with other oxides, such as ceria (CeO2) and / or titania (TiO2), in the field of optics, in particular to coat lenses (in order to make them scratch-resistant and / or anti-glare). In these cases, ceria and / or titania usually define up to about 40% by weight of the composition with zirconia.

The combination of zirconia with itria (Y2O3) is used in fuel cells (as it stabilizes the cubic structure of the zirconia). In these cases, usually, itria is used up to about 10% by weight of the composition with zirconia.

Thin states of hafnia (HfO2) have proved useful in the field of optics (to coat lenses in order to make them scratch-resistant) and in the field of electronics (for the creation of thin insulating barriers).

Alumina is used in catalysis and electronics for its dielectric properties (particularly in capacitors). WO2 is used in solar thermal systems, as it allows visible light to pass while reflecting infrared radiation. MoO2 is used in electronics and solar cells as a current barrier. Fe2O3 is a biocompatible material and can also be used for the production of Fe3O4 useful in electronics for spin injection systems. Silver oxide is often used as an antimicrobial. Ta2O5 is used to produce capacitors in the electronic field.

In addition to the above, ceria is used in the field of fuel cells and as an anti-scratch and / or anti-reflective material; titania can be used in the field of orthopedic prostheses, in catalysis and / or in photovoltaic cells.

The methodologies developed up to now for the realization of thin layers containing the above-mentioned oxides (individually or in combination with each other) have one or more drawbacks, among which we mention: obtaining insufficiently thin layers; relatively high production costs; inability to produce sufficiently homogeneous and / or pure layers; inability to produce adequately smooth and / or imperfect-free layers (pin holes); inability to bind sufficiently stably to a substrate.

The above problems are particularly felt in the production of thin layers of hafnia, zirconia and / or tungsten oxide. This is probably due to the fact that afnia, zirconia and tungsten are particularly hard materials.

The purpose of the present invention is to provide a method for depositing a layer of a material which allows to overcome, at least partially, the drawbacks of the known art and which is possibly, at the same time, easy and economical to produce.

SUMMARY

According to the present invention there is provided a method for depositing a layer of a material according to what is disclosed in the independent claim that follows and, preferably, in any one of the claims directly or indirectly dependent on the independent claim.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below with reference to the attached drawings, which illustrate some non-limiting examples of implementation, in which:

Figure 1 schematically and partially shows in section an apparatus which can be used in a method according to the present invention;

Figure 2 schematically illustrates an apparatus that can be used in a method according to the present invention for depositing a material with several components;

- figure 3 is an optical microscopy image of an alumina sample deposited on PET by the method according to the present invention (the illustrated bar indicates the measurement of 100 µm);

- figure 4 is a SEM image of a section of the sample of figure 3 (the illustrated bar indicates the measurement of 200nm);

- figure 5 is a SEM image of a section of the sample of figure 3 (the illustrated bar indicates the measurement of 1µm);

- Figures 6 to 8 illustrate optical spectra of a Tantalum oxide feather (starting from Tantalum in an oxidizing atmosphere) obtained during the application of a method according to the present invention; the wavelength in nm is shown on the abscissa; in ordinate the intensity is reported in arbitrary units;

- figure 9 illustrates an optical spectrum of a Molybdenum oxide plume (starting from Molybdenum in an oxidizing atmosphere) obtained during the application of a method according to the present invention; the wavelength in nm is shown on the abscissa; in ordinate the intensity is reported in arbitrary units;

- figure 10 illustrates an optical spectrum of a titanium oxide plume obtained during the application of a method according to the present invention; the wavelength in nm is shown on the abscissa; in ordinate the intensity is reported in arbitrary units;

- figure 11 illustrates an optical spectrum of an Indium oxide plume (starting from Indium in an oxidizing atmosphere) obtained during the application of a method according to the present invention; the wavelength in nm is shown on the abscissa; in ordinate the intensity is reported in arbitrary units;

- figure 12 illustrates an optical spectrum of a zinc oxide feather (starting from zinc in an oxidizing atmosphere) obtained during the application of a method according to the present invention; the wavelength in nm is shown on the abscissa; in ordinate the intensity is reported in arbitrary units; And

- figure 13 illustrates an optical spectrum of a Platinum plume obtained during the application of a method according to the present invention; the wavelength in nm is shown on the abscissa; the ordinate shows the intensity in arbitrary units.

FORMS OF IMPLEMENTATION OF THE INVENTION

In Figure 1, 1 indicates as a whole an apparatus for the deposition of a layer comprising (in particular, consisting of) a material by means of pulsed plasma deposition (PPD).

In some cases, the material comprises (according to some embodiments, it is made up of) a metal oxide and is obtained starting from a specific component. The determined component is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron , Aluminum, Tungsten, Tantalum, Molybdenum, Silver, Indium, Platinum and a combination of them. Additionally or alternatively, the determined component is Zinc.

According to some embodiments, the determined component is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, Zirconium, Hafnium , Cerium, Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver, Indium and a combination of them. More specifically, the determined component is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver and a combination of them.

According to some embodiments, the determined component is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3.

According to some embodiments, the determined component is chosen from the group consisting of: zirconia, afnia, tungsten and a combination thereof.

More precisely, the determined component is chosen from the group consisting of: zirconia, afnia and a combination of them. According to some embodiments, the determined component comprises (Ã ̈) zirconia. According to other forms of implementation, the determined component includes (Ã ̈) afnia.

According to some embodiments, the determined component is chosen from the group consisting of: Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver and a combination thereof.

In particular, the material is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, FeO, Fe3O4, Alumina (Al2O3), WO2, Ta2O5, MoO2, Ag2O, Indium oxide (In2O3), Platinum. In addition or alternatively the material is zinc oxide (ZnO).

According to some forms of implementation, the material is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, FeO, Fe3O4, Alumina (Al2O3), WO2, Ta2O5, MoO2, Ag2O, Indium oxide (In2O3). In particular, the material is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, FeO, Fe3O4, Alumina (Al2O3), WO2, Ta2O5, MoO2, Ag2O.

Obviously, a relative (starting) material corresponds to each given component. For example, if the determined component is zirconia, the material is also zirconia; or, if the determined component is tungsten, the material is tungsten oxide (which is obtained as a result of the oxidation of tungsten).

According to some embodiments, the determined component is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3. In these cases, the material is also chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3.

The apparatus 1 comprises a device 2 for the generation of plasma (ie an at least partial ionization of a rarefied gas) and for directing a (pulsed) flow of electrons towards a target 3, which has (in particular it is constituted da) the determined component, so that at least part of the determined component separates from the target 3 and the material deposits on a surface 4â € ™ of a substrate 4.

It should be noted that surprisingly (in consideration of the fact that other methodologies have proved unable) it is possible to obtain a layer of the material on the substrate 4.

It has been experimentally observed that for the determined components identified above, surprisingly, the frequency with which the electron flow is directed towards the target 2 plays an important role. In particular, this frequency, in order to have a good quality deposit, is it should be between 2Hz and 100Hz.

Advantageously, (the plasma is generated and d) the flow of electrons is directed towards the target 3 with a frequency of at least 2Hz (in some cases, at least 3Hz; in particular, at least 4Hz; more precisely, at least 10Hz). According to some embodiments, (the plasma is generated and d) the flow of electrons is directed towards the target 3 with a frequency up to 30Hz (in particular, up to 25Hz; more precisely up to 20Hz). More precisely, (the plasma is generated and d) the flow of electrons is directed towards target 3 with a frequency from 17Hz to 23Hz.

It should be noted that the frequencies identified above are particularly advantageous as they allow to obtain a particularly good ablation and deposition. Too high frequencies can lead to overheating of target 3 with particles that are released in an uncontrolled way.

Furthermore, relatively low frequencies allow to use relatively delicate substrates 4 (substrate 4 does not overheat). Substrates 4 for which it is important not to raise the temperature are, for example, substrates which have low glass transition temperatures and which, at too high temperatures, are therefore unable to guarantee a stable support for deposition.

Advantageously, the substrate 4 comprises (in particular it consists of) an inorganic substance. In some cases, the inorganic material is glass, alkali-free glass, quartz, silicon, molybdenum, copper, stainless steel (and other metals).

In some cases, the substrate 4 comprises (in particular, Ã) a polymeric substance having a glass transition temperature from 70 ° C (in particular, from 80 ° C) to 150 ° C (in particular, up to 140 ° C ).

According to some embodiments, the substrate 4 comprises (in particular, it consists of) a polymeric material.

According to specific embodiments, the polymeric material is selected from the group consisting of: polyesters, polyolefins, polyimides, phenolic resins, polyanhydrides, silicone rubbers, copolymers. In particular, the polymeric material is selected from the group consisting of: PTFE (polytetrafluoroethylene), PET (polyethylene terephthalate), PEN (polyethylene terephthalate), PEDOT (Poly (3,4-ethylenedioxythiophene), polyaniline, polypyrrole, polythiophene, polyparaphenene, polyfluorophene, polyparaphenylene vinyl (PPV).

More precisely, High molecular weight polypropylene (PPAPM - from 10000 to 100000 Da), PP, PET, Mylar, PE, PEN.

Advantageously, the polymeric material is PET. It should be noted that PET has a relatively low glass transition temperature (about 80 ° C), but at the same time excellent mechanical characteristics, which make it an excellent support for thin layers of the oxide materials identified above. However, until now it has not been possible to obtain good quality thin layers on PET (due to its relatively low glass transition temperature). Surprisingly, with the present invention it was possible to obtain this type of result.

The target 3 and the substrate 4 are arranged inside an external chamber 24 of the apparatus 1, which also comprises a heating unit HU for heating the substrate 4. According to some embodiments, the heating of the substrate 4 occurs by irradiation with infrared rays. Advantageously, the heating of the substrate 4 takes place by heating a rear portion of 4 (in particular by heating a surface 4 'of the substrate 4 opposite the surface 4'). In this regard, it should be noted that the substrate 4 is arranged between the heating unit HU and the target 3.

During the deposition phase of the material, the substrate 4 is kept (during deposition) at a (deposition) temperature below 150 ° C (in particular, below 100 ° C; more precisely, below 90 ° C). Advantageously, during the deposition step, the substrate 4 is kept at a (deposition) temperature higher than 25 ° C (more precisely at least 26 ° C).

Low temperatures (in particular, below 150 ° C) are maintained when the substrate 4 comprises (Ã ̈ di) a delicate substance at the temperature (for example organic, more precisely polymeric).

It has been experimentally observed that, surprisingly, for the materials identified above to be deposited, the distance between the substrate 4 and the target 3 plays an important role. This distance, in order to have a good quality deposit, should be between 10 mm and 120 mm.

Advantageously, the distance between substrate 4 and target 3 is at least 70 mm (more precisely, at least 80 mm). The distance between substrate 4 and target 3 is up to about 120 mm (more precisely, up to 100 mm; in particular, up to 90 mm). It has been experimentally observed that this distance allows a good heat dissipation between target 3 (which heats up due to the impact of the electrons) and substrate 4; at the same time, surprisingly, the quality of the deposition is of good quality. These distances are therefore particularly useful when the substrate 4 comprises (Ã di) a temperature sensitive substance. For example, organic (polymeric) material may be damaged at higher temperatures.

According to specific embodiments, the target 3 and the substrate 4 are arranged at a distance of at least 10 mm (in particular, at least 27 mm; more precisely, at least 30 mm). The target 3 and the substrate 4 are arranged at a distance of up to 100 mm (in particular, up to 90 mm; advantageously, up to 70 mm). Reduced distances allow to obtain an optimal deposition. Reduced distances can be used when the substrate 4 comprises (in particular, it consists of) a substance inert to the increase of temperature (for example, when it comprises an inorganic substance).

According to some embodiments, the substrate 4 is kept at a (deposition) temperature higher than about 90 ° C (in particular, higher than 100 ° C). Advantageously, the substrate 4 is kept at a temperature of at least 200 ° C (up to 400 ° C) to ensure that the determined component is better distributed on the surface. These temperatures are particularly useful where it is intended to obtain layers for optical and / or electronic uses. Temperatures higher than 100 ° C are advantageously maintained with substrates 4 of inorganic materials.

According to further embodiments, the substrate 4 is kept at a temperature higher than 600 ° C (in particular, higher than 700 ° C). In these cases the substrate 4 is kept at a temperature up to 850 ° C. Such high temperatures are used to obtain usable layers in fuel cells.

The apparatus 1 also comprises a covering element C movable between an operative position (illustrated in broken lines) and a rest position (illustrated in a continuous line).

In use, before starting to deposit the determined material on the substrate 4, the target 3 is cleaned. A (pulsed) beam of electrons (generated by device 2) is directed against target 3 so that the surface layer (on which impurities can potentially be deposited) of target 3 itself is removed and the relative particles are intercepted by the target 3. ™ cover element C (arranged in its operative position).

Once the target 3 has been cleaned, it is possible to proceed with the deposition of the determined component on the substrate 4 in order to obtain a better quality layer. During the deposition, the covering element C is kept in its rest position in order to allow the particles of determined material to settle freely on the surface 4â € ™.

Advantageously, target 3 is connected to ground. In this way, target 3 does not reject (and indeed attracts) the flow of electrons even when the electrons have already hit target 3.

The device 2 comprises a hollow element 5, which is adapted to act as a cathode and has (externally delimits) an internal cavity 6; and an activation electrode 7, which comprises (in particular, is constituted by) an electrically conductive material (in particular, metal). The activation electrode 7 is arranged inside the cavity 6 (delimited by the hollow element 5). In particular, the hollow element 5 comprises (more particularly, it is made up of) an electrically conductive material (more particularly, a metallic material).

In particular, by electrically conductive material (eg stainless steel, tungsten, molybdenum, chromium, iron, titanium) we mean a material that has an electrical resistivity (measured at 20 ° C) lower than 10-1 Î © .m. Advantageously, the electrically conductive material has an electrical resistivity (measured at 20 ° C) lower than 10-3 Î © .m.

The activation electrode 7 extends through a wall 8 of the hollow element 5. A ring 9 of electrically substantially insulating material (in particular ceramic) is interposed between the activation electrode 7 and the wall 8.

In particular, by electrically substantially insulating material is meant a material which has an electrical resistivity (measured at 20 ° C) higher than 103 Î © .m. Advantageously, the electrically non-conductive material has an electrical resistivity (measured at 20 ° C) higher than 107 Î © .m (more advantageously, higher than 109 Î © .m). According to some embodiments, the electrically substantially insulating material is a dielectric material.

The device 2 also comprises a resistor 10, which connects the activation electrode 7 to ground and has a resistance of at least 100 Ohm, advantageously of at least 1 kOhm. In particular, the resistor 10 has a resistance of about 20kOhm.

Inside cavity 6 there is a rarefied gas. According to some embodiments, the cavity 6 contains rarefied gas at a pressure lower than or equal to 10-1 mbar (in particular, lower than 5x10-2 mbar). Advantageously, the rarefied gas contained inside the cavity 6 has a pressure higher than or equal to 10-3 mbar (more in particular higher than 5x10-3 mbar). More precisely, the pressure inside cavity 6 is approximately 10-2 mbar.

In this regard, it should be noted that apparatus 2 includes a gas supply unit (per se known and not illustrated) to feed an anhydrous gas (non-limiting examples - oxygen, nitrogen, argon, helium, NO, xenon etc.) inside the cavity 6 through a duct 23. Along the duct 23 there is a flow regulator (of a type known per se and not illustrated; for example a valve) able to regulate the quantity of flow which is fed to the cavity 6 and therefore the pressure inside the cavity 6 itself. In use, the pressure is adjusted in order to reach the appropriate values to obtain the generation of the plasma.

The hollow element 5 is electrically connected to an activation group 11, which is able to decrease (in particular, starting from an electric potential substantially equal to zero) the electric potential of the hollow element 5 by at least 8kV (in particular, at least 12 kV). More precisely, the activation group 11 decreases the electric potential of the hollow element 5 by at least 16kV (in particular, at least 18kV). The activation group 11 decreases the electric potential of the hollow element 5 up to 25kV (in particular, up to 24kV; more precisely, up to 20kV). The decrease of the electric potential of the hollow element 5 occurs in less than 20 ns. In particular, this occurs by directing an electrical charge impulse of at least 0.16 mC (up to 0.5 mC) towards the hollow element 5 itself. Advantageously, the activation group 11 is able to force the hollow element 5 to decrease the potential in less than 15 ns (more precisely, in less than 10 ns); in some cases, in less than about 4 ns. In this way the plasma is created (inside the hollow element 5).

Note that the potentials identified above are particularly advantageous as they allow the flow of electrons to have sufficient energy to ablate the determined component (even when, as mentioned, it is particularly hard). Zirconia, afnia and tungsten (and a combination thereof) are components determined with high hardness.

According to some embodiments, the activation group 11 decreases the electric potential of the hollow element 5 up to 16 kV (with the above indicated speeds). This can be particularly advantageous when the determined component is not particularly hard (such as when the determined component is chosen from the group consisting of: Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron, Aluminum, Tantalum, Molybdenum, Silver and their combination).

The hollow element 5 is connected to earth. In this way, when the emission of the electron flow is not effected, the hollow element 5 is kept at substantially zero potential and the risk of spontaneous discharges between the hollow element 5 and the activation electrode 7 It is essentially canceled.

In particular, a resistor 12 is connected between the hollow element 5 and ground. According to some embodiments, the resistor 12 has a resistance of at least 50 kOhm. Advantageously, the resistor 12 has a resistance of at least 100 kOhm, in particular of about 0.5 MOhm. According to some embodiments, the resistance is less than 1 MOhm.

Activation group 11 includes a thyratron 13; a capacitor 14, which has an armature connected to an anode 15 of the thyratron 13 and a further armature connected to the hollow element 5; and an electric power supply 16, which has a positive electrode 17 electrically connected to the anode 15 and a negative electrode 18 connected to ground.

Thyratron 13 also has a cathode 19, which is grounded.

Note that capacitor 14 is electrically connected to ground (specifically, through resistor 12).

The activation group 11 also includes a control unit 20 of the thyratron 13, which control unit 20 is adapted to operate the thyratron 13 and is connected to ground.

The device 2 also comprises an operator interface unit (known per se and not illustrated), which allows an operator to adjust the operation (for example the activation and / or modification of operating parameters) of the device 2 itself.

The device 2 also comprises a tubular element 21, which comprises (in particular, is of) an electrically substantially insulating material (in particular glass, quartz or haphnia) and is connected to the hollow element 5. The The tubular element 21 has two open ends 21a and 21b and an internal lumen which puts the cavity 6 in fluid communication with the outside (in particular, with the external chamber 24).

The hollow element 5 (with the exception of the duct 23 and the tubular element 21) is fluid-tight towards the outside.

The tubular element 21 extends at least partially inside the external chamber 24 (figure 1), in which the target 3 and the substrate 4 are arranged. The tubular element 21 and the relative internal lumen have respective cross sections substantially circular.

Inside the external chamber 24 there is a rarefied gas (according to some embodiments, anhydrous). According to some embodiments, the outer chamber 24 contains rarefied gas at a pressure lower than or equal to 10-2 mbar (in particular, lower than 10-3 mbar). Advantageously, the rarefied gas contained inside the external chamber 24 is kept at a pressure lower than or equal to 10-2 mbar thanks to a suction device (of a known type and not illustrated). In particular, the rarefied gas contained inside the external chamber 24 has a pressure higher than or equal to 10-4 mbar (more precisely, higher than in particular higher than 10-3 mbar). The rarefied gas contained inside the external chamber 24 has a pressure lower than or equal to 5x10-3 mbar (more particularly, lower than or equal to 3x10-3 mbar).

According to alternative embodiments (in particular, when it is desired to make the determined component react with at least a part of the rarefied gas), the cavity 6 contains rarefied gas at a pressure greater than or equal to 5x10-4 mbar. In these cases, advantageously, the rarefied gas comprises (mainly) (Ã ̈) oxygen.

It has been experimentally observed that, surprisingly, when the determined component is one of Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver (and / or Indium) (and / or Zinc) and a combination of them, and the rarefied gas comprises (mainly) (Ã ̈) oxygen, the component surprisingly reacts with oxygen so that the material deposited on the substrate 4 is a metal oxide. More specifically, the material obtained as a result of the reaction with oxygen (according to the component determined) is chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2 ), Itria (Y2O3), Fe2O3, FeO, Fe3O4, Alumina (Al2O3), WO2, Ta2O5, MoO2, Ag2O (and / or Indium oxide) (and / or Zinc oxide) and a combination thereof.

The pressure (from about 5x10-3mbar to about 5x10-2mbar) inside the cavity 6 is kept (slightly) higher than that present in the external chamber 24 (in particular, by feeding small quantities of gas through a duct 23).

According to the embodiment illustrated in Figure 1, the tubular element 21 extends through a wall 22 of the hollow element 5 (opposite the wall 8), partially inside the cavity 6 and partially outside ( in particular, inside the external chamber 24).

According to specific embodiments, the tubular element 21 has a length from 90 mm to 220 mm. The tubular element 21 has a diameter from about 4 mm to about 10 mm. The internal lumen 21c has a diameter from about 1.5 to about 8 mm. The external chamber 24 is constructed in such a way as to be fluid-tight with respect to the external environment.

The distance between target 3 and extremity 21b is between 1 and 20 mm (more precisely between 3 and 8 mm).

The device 2 also comprises an external element 25, which is arranged externally to the hollow element 5 (in particular, in the external chamber 24) in correspondence with the tubular element 21 and acts as an anode. In particular, the hollow element 5 is arranged in correspondence with an intermediate part of the tubular element 21 (ie not in correspondence with one end of the tubular element 21). In other words, the hollow element 5 is arranged along the tubular element 21 (ie not at one end of the tubular element 21) and acts as an anode. In particular, the external element 25 is arranged in contact with an external surface of the tubular element 21.

The external element 25 is shaped in such a way as to be arranged around the tubular element 21; in particular, the external element 25 has a hole through which the tubular element 21 extends. According to specific embodiments, the external element 25 has an annular shape.

The device 2 also comprises a potential maintenance unit 26, which is electrically connected to the external element 25 to maintain the electric potential of the external element 25 substantially grounded.

In use, the activation unit 11 imposes a potential difference between the hollow element 5 and the activation electrode 7 according to the parameters described above. As a consequence of this, plasma is generated (ie an at least partial ionization of the rarefied gas) inside the cavity 6.

When electrons formed inside the cavity 6 enter the tubular element 21, the potential difference, which is established with the external element 25, allows the electrons themselves to be accelerated along the tubular element 21 towards the target 3. These electrons, during their movement, strike further gas molecules and therefore determine the emission of secondary electrons which, in turn, are accelerated towards the target 3.

According to specific embodiments, the apparatus 1 and the device 2 (except for what concerns the external chamber 24 and its contents) of figure 1 have a structure and operation similar to the apparatus and the device described in the patent application PCTIB2010000644.

According to some embodiments not illustrated, the apparatus 1 and the device 2 have a similar structure and operation (with an appropriate adaptation of the operating parameters) to the apparatuses and devices described in the patent application according to the PCT convention claiming the Italian priority BO2010A000525 of the same applicant.

It should be noted that the apparatuses and devices and apparatuses described in the two aforementioned patent applications are particularly advantageous as they allow to obtain excellent deposition efficiencies. In particular, it has been experimentally observed that some very hard components (more precisely, zirconia, hafnia and tungsten) are very difficult to remove and deposit by other types of plasma generation devices. The devices 2 and apparatuses 1 described above and of the two aforementioned patent applications, on the other hand, surprisingly allow to remove significant quantities of these components and to obtain layers of good quality.

According to some embodiments not illustrated, the apparatus 1 and the device 2 have a similar structure and operation (with an appropriate adaptation of the operating parameters) to the apparatuses and devices described in the patent application PCTEP2006003107.

According to some embodiments, the layer comprises a further material. The further material is chosen from the group consisting of: ceria, itria, titania and a combination of them.

According to specific forms of implementation, the additional material is itria. According to further embodiments, the further material is chosen from the group consisting of: ceria, titania and a combination of them.

To obtain the layer (which contains more materials), the material and the further material are deposited (substantially simultaneously) by deposition with pulsed plasma.

By way of example, Figure 2 schematically illustrates an apparatus 1 comprising two devices 2 and 2â € ™ for the generation of plasma, two targets 3 and 3â € ™ of different composition and a single substrate 4. P and Pâ € ™ schematically illustrate some feathers that are generated from the surfaces of targets 3 and 3â € ™, respectively. In particular, target 3 comprises (is made up of) the determined component; target 3â € ™ includes (is made up of) the additional material (ceria and / or tiatania and / or itria).

It should be noted that the feathers which are produced on the different targets are surprisingly combined in such a way as to allow the mixing of the different materials and form the aforementioned layer on the substrate 4. In this way, it is possible to skip (or at least greatly simplify) the preparation of target 3. It is also possible that in this way, by varying the various operating parameters, the composition of the first material can be very easily changed.

Alternatively, to obtain a material with several components, it is possible to use a target consisting of a mixture of these components. However, these targets are more expensive and difficult to make.

In some cases it is useful that the material which is deposited on the substrate 4 is a multilayer material. In these cases, the device 1 is first used for the application of the material, then (after having replaced the target 3) for the application of the further component (or vice versa, first the further component then the component determined).

Alternatively, it is possible to obtain a multilayer material using the apparatus 1 of figure 2 by operating alternatively (not simultaneously) the devices 1 and 1â € ™. This methodology allows time savings compared to the first.

According to an aspect of the present invention, a method is provided for depositing on a substrate 4 a layer comprising a given material. In some cases, the determined material consists of a metal oxide.

The determined material is obtained starting from at least one determined component chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver, Indium, Platinum (and Zinc) and a combination of them. The method comprises a deposition step, which is carried out by pulsed plasma deposition (PPD) and during which a plasma generation device 2 generates the plasma and directs at least one electron flow towards at least one target 3 comprising the component determined in such a way that at least part of the determined component is emitted by the target 3 and at least part of the determined material is deposited on a first surface 4 'of the substrate 4.

Advantageously, the method is implemented in accordance with what has been described above in relation to apparatus 1.

According to a further aspect of the present invention, a substrate 4 is provided with a layer obtained in accordance with the previous aspect of the present invention.

According to a further aspect of the present invention, a substrate 4 is provided with a layer obtainable in accordance with the previous aspect of the present invention.

The methodologies developed up to now for the realization of thin layers containing one of the aforementioned materials have one or more drawbacks, among which we mention: obtaining insufficiently thin layers; relatively high production costs; inability to produce sufficiently homogeneous and / or pure layers; inability to produce adequately smooth and / or imperfect-free layers (pin holes); inability to bind sufficiently stably to a substrate.

On the basis of what has been described above and of the experimental tests carried out (see below) it is clear that with the method of the present invention it is possible to create a layer of very low thickness (in some cases even substantially crystalline), substantially free of imperfections (for example for example, through holes - pinholes), with a high degree of purity and homogeneity, at relatively low costs and with relatively high yields.

These advantages are obtainable with a very thin layer which therefore allows to reduce the overall dimensions and has low production costs.

Unless the contrary is explicitly indicated, the content of the references (articles, books, patent applications, etc.) cited in this text is referred to here in full. In particular, the aforementioned references are incorporated herein by reference.

Further characteristics of the present invention will emerge from the following description of two merely illustrative and non-limiting examples.

Example 1

Preparation of a ZrO2 target

The target for the deposition of ZrO2 layers by the PPD method was prepared by compressing at room temperature ZrO2 powder (Sigma-Aldrich, purity 99.999%). Alternatively, it is possible to prepare the garlic by compressing with a force of 15 tons of the ZrO2Y-stabilized powder in a (circular) mold with a diameter of 32 mm. The 5 mm high tablets obtained were subjected to a heat treatment of 1650 ° C for 12 hours in an oxygen atmosphere and then cooled with the spontaneous cooling rate of the oven (oven off and closed, temperature drop time from 1650 ° C to 80 ° C about 14 hours).

ZrO2Y-stabilized targets can also be purchased from Sigma Aldrich.

Example 2

Deposition of thin layers of ZrO2

The ZrO2 target was mounted on a rotating target holder (with rotation speed 0.1 Hz <f <5 Hz, more precisely f = 0.5 Hz) and ablated with the above described device 1. The acceleration voltage of the electron beam has been chosen between 8 kV <V <24 kV, more precisely it has been fixed at 22 kV. The frequency of generation of electron and plasma packets has been varied between 3 Hz <f <30 Hz, in particular it has been set at 20 Hz. The oxygen atmosphere has been used in the deposition chamber as the € ™ working atmosphere. The working gas pressure has been varied between 5 * 10-5 mbar <p <10-2 mbar, in particular it has been set at 1.5 * 10-3 mbar. The substrate chosen from inorganic materials (glass, alkaline glass, quartz, silicon, molybdenum, copper, stainless steel and other metals) and organic materials (high molecular weight polypropylene (PPAPM), PP, PET, Mylar, PE, etc.) , in particular PPAM, cut in the shape of a rectangle with dimensions of 1 x 1 inch was fixed on a rotating sample holder (the rotation speed 0.5 Hz <f <5 Hz preferably f = 1 Hz). The distance between the ablated surface of the target and the deposition surface of the sample was chosen between 30 mm <d <90 mm, it was set at 70 mm.

The substrate temperature did not exceed 90 ° C during deposition. The deposition speed was controlled â € œin situâ € by using the green laser thickness gauge. The quality of the deposited material was inspected using the optical spectrometer (wavelength range 200 nm <Î »<900 nm.

Example 3

Preparation of an aluminum target

The aluminum target was obtained from a block of pure aluminum (purity Al 99.999%, Alfa Aesar). This block was turned into the shape of a cylinder with a diameter of 35 mm and a height of 10 mm. After turning, the aluminum cylinder was polished using sandpaper number 400, 600, 800 and 1200. Before mounting the target on the target holder of the PPD deposition chamber it was washed in a bath ultrasound in acetone, isopropyl alcohol and double distilled water. Before deposition of the alumina on the substrate, the target was conditioned (i.e. the target was subjected to the ablation process for about 15 min under the conditions identical to the deposition of the layer on the substrate, preventing the target feather from settling on the substrate through the use of a sample protection screen).

Example 4

Deposition of thin layers of alumina

The aluminum target was mounted on a rotating target holder (rotation speed 0.1 Hz <f <5 Hz preferably f = 0.5 Hz) and ablated with the PPD source described in the (patent application) candle). The acceleration voltage of the electron beam was chosen from 12 kV <U <20 kV, preferably 16 kV. The frequency of generation of electron and plasma packets was varied between 20 Hz <f <100 Hz, preferably 50 Hz. The oxygen atmosphere was used in the deposition chamber as the working atmosphere. The working gas pressure was varied between 5 * 10-4 mbar <p <10-2 mbar, preferably 1.0 * 10-3 mbar. The high molecular weight Polypropylene substrate - PPAPM - (other substrates include PET, PTFE, PP, graphite, silicon, quartz, glass, copper, molybdenum, 304 stainless steel, gold, silver, etc.) in the form of a rectangle with dimensions of 20 x 30 mm was fixed on a rotating sample holder. The distance between the ablated surface of the target and the deposition surface of the sample was chosen between 27 mm <d <100 mm, preferably 100 mm for substrates of organic materials and 35 mm for substrates of inorganic materials. The deposition speed was controlled â € œin situâ € by using the green laser thickness gauge. The quality of the deposited material was inspected using the optical spectrometer (wavelength range 200 nm <Î »<900 nm).

Example 5

Results for alumina deposition The deposition rate was studied by deposition on a silicon substrate. The growth of the layer is non-linear over time - the 30 min deposition. makes the layer thickness 1.2 µm. The deposition of 60 min. demonstrates the thickness of 1.55 µm. The thicknesses of the deposited layers for different samples vary from 20 nm to 3.57 µm. The composition of the material measured by the EDS method is documented by the EDS 34 sample which demonstrates 40% at. % Al, 1 -2 at. % C, 60 â € “63 at. % O, more trace than Si. The macroscopic morphology of the layers is demonstrated on an optical microscopy image (Fig. 3). The low microscopic roughness and the grain morphology of the deposited layer are shown in figures 4 and 5.

Example 6

Tantalum oxide, molybdenum oxide, titania, indium oxide, zinc oxide and platinum depositions were also performed. The optical spectra of the feathers are shown in Figures 6 to 11.

Claims (1)

R I V E N D I C A Z I O N I 1.- Method for the deposition on a substrate (4) of a layer comprising a specific material; the material is obtained starting from at least one determined component chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, Zirconium, Hafnium, Cerium , Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver, Indium, Platinum and a combination thereof; the method comprises a deposition step, which is carried out by pulsed plasma deposition (PPD) and during which a device (2) for the generation of plasma generates the plasma and directs at least one electron flow towards at least a target (3) comprising the determined component so that at least part of the determined component is emitted from the target (3) and at least part of the material is deposited on a first surface (4â € ™) of the substrate (4); the device (2) comprises a hollow element (5), which has a cavity (6) and is able to act as a cathode; a substantially dielectric tubular element (21), which extends from the hollow element (5) to an external chamber (24); an external element (25), which acts as an anode, is arranged externally to the hollow element (5) and externally to and in correspondence with the tubular element (21); and an activation group (11); the target (3) and the substrate (4) being arranged in the outer chamber (24). 2. A method according to claim 1, wherein the plasma is generated and the electron flow is directed towards the target (3) with a frequency from 2Hz to 100Hz; the substrate (4) and the target (3) being arranged at a distance from 10 mm to 120 mm. 3. A method according to Claim 1 or 2, wherein the device (2) comprises an activation electrode (7) arranged at least partially inside the cavity (6); the activation group (11) is electrically connected to the hollow element (5) and decreases the electric potential of the hollow element (5) by 16kV to 25kv in less than 20 ns. 4. A method according to Claim 3, in which the activation group (11) decreases the electric potential of the hollow element (5) by up to 24kV, in particular up to 22kV. 5.- Method according to Claim 3 or 4, in which in the activation group (11) it decreases the electric potential of the hollow element (5) by at least 18kV with an overall charge pulse from 0.16 mC to 0 , 5 mC. 6. A method according to one of the preceding claims, in which the plasma is generated and the flow of electrons is directed towards the target (3) with a frequency from 3Hz to 30Hz. 7. A method according to claim 6, wherein the plasma is generated and the electron flow is directed towards the target (3) with a frequency of 4Hz to 20Hz. 8. A method according to one of the preceding claims, wherein the substrate (4) comprises a substance with a glass transition temperature from 80 ° C to 150 ° C; the substrate (4) and the target (3) being arranged at a distance from 70 mm to 120 mm. 9. A method according to one of the preceding claims, wherein the device (1) comprises first resistive means (10), which electrically connect the activation electrode (7) to ground. 10. A method according to Claim 9, wherein the first resistive means (10) have a resistance greater than 100 Ohm. 11.- Method according to one of the preceding claims, in which the determined material consists of a metal oxide and is obtained starting from at least one determined component chosen from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), Ceria, (CeO2), Titania (TiO2), Itria (Y2O3), Fe2O3, Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver, Indium and a combination of them. 12.- Method according to one of the preceding claims, in which the determined component is selected from the group consisting of: Zirconium, Hafnium, Cerium, Titanium, Yttrium, Iron, Aluminum, Tungsten, Tantalum, Molybdenum, Silver and a combination thereof; the external chamber contains oxygen at a pressure from 5x10-4 mbar to 10-2 mbar; the determined component emitted by the target (3) reacts with the oxygen present inside the external chamber in order to obtain said material. 13.- Method according to one of claims 1 to 11, wherein the determined component is selected from the group consisting of: Zirconia (ZrO2), Afnia (HfO2), tungsten and a combination thereof; the activation group (11) decreases the electric potential of the hollow element (5) by from 16 kV to 25 kv in less than 20 ns. 14.- Method according to one of the preceding claims, in which the target (3) and the substrate (4) are arranged in an atmosphere containing a substance selected from the group consisting of: Nitrogen, NO, Oxygen and a combination thereof. 15. A method according to one of the preceding claims, wherein the layer comprises a further material; the further material being applied by pulsed plasma deposition (PPD). 16. A method according to Claim 15, wherein the further material is applied by means of a further device (2â € ™) for generating plasma, in particular defined as the device (2) of one of the preceding claims.