WO2023199081A1

WO2023199081A1 - Method and system for the manufacture of products with a structured surface

Info

Publication number: WO2023199081A1
Application number: PCT/IB2022/000221
Authority: WO
Inventors: Gemma Garcia Mandayo; Isabel Ayerdi Olaizola; Enrique CASTAÑO CARMONA; Sergio SANCHEZ MARTIN; Oihane BELDARRAIN FERNANDEZ; Santiago Miguel Olaizola Izquierdo
Original assignee: Centro de Estudios Investigaciones Tecnicas CEIT
Current assignee: Centro de Estudios Investigaciones Tecnicas CEIT
Priority date: 2022-04-11
Filing date: 2022-04-11
Publication date: 2023-10-19
Anticipated expiration: 2024-10-11

Abstract

The present invention belongs to the field of the manufacture of structured substrates and coatings, such as the generation of microstructures and nanostructures on substrates or coatings, by means of combining a chemical deposition method (such as Aerosol Assisted Chemical Vapor Deposition) with local heating means (such as laser). More precisely, the invention refers to a method for manufacturing a product with a structured surface comprising the steps of: a) depositing an aerosol onto a deposition surface, wherein the aerosol comprises a carrier gas (1) and at least one liquid precursor capable of undergoing a thermally induced chemical reaction to generate a solid product, and b) locally applying heat on a partial area of the deposition surface to promote the thermally induced chemical reaction, such that said partial area corresponds to an elevation of the structured surface with respect to an adjacent area of said partial area, adjacent area where the heat is not applied. The invention also refers to the corresponding method and system to carry out the invention, as well as to the product with a structured surface generated with the aforementioned method of the invention.

Description

DESCRIPTION

METHOD AND SYSTEM FOR THE MANUFACTURE OF PRODUCTS WITH A STRUCTURED SURFACE

Field of the invention

The present invention belongs to the field of the manufacture of structured substrates and coatings, such as the generation of microstructures and nanostructures on substrates or coatings, by means of combining a chemical deposition method (such as Aerosol Assisted Chemical Vapor Deposition) with local heating means (such as laser). The invention refers to the corresponding method and system to carry out the invention, as well as to the product with a structured surface generated with the aforementioned method of the invention.

Background art

A variety of techniques to deposit material, which allow to generate substrates or coatings, are known in the state of the art. Some of these deposition techniques with their particularities are disclosed below:

Spray coating: This technique as the name implies creates coatings on a substrate, by physically applying a spray of droplets or particles that deposit on a substrate. Spray coating can be carried out at room temperature, as well as at high temperature (also known as thermal spray coating). However, spray coating results in non-uniform coating, in difficulty to coat certain areas of non-planar surfaces, and in a low degree of adhesion of the coating layer to the applied substrate.

Physical vapor deposition (PVD): This term describes a series of coating process, such as sputtering or evaporation, in which a deposition material is vaporized and then condensed on a surface so that it deposits on such surface, coating it. Not only coatings but also substrates may be manufactured by PVD. Chemical vapor deposition requires to be carried out under high vacuum conditions so that the presence of other gases which may contaminate the coated material is avoided. Moreover, with this technique it is also difficult to coat certain areas of non- planar surfaces. Chemical vapor deposition (CVD): This technique is a coating process in which the reactants are provided in gaseous form, and such gases can react with the surface to create reaction products on it, hence the reaction products being deposited on the surface creating a coating over it. Not only coatings but also substrates may be manufactured by CVD. Chemical vapor deposition is carried out under vacuum conditions in order to reduce the working temperature required to volatilize the precursors, but it may also be carried out at atmospheric pressure (atmospheric pressure CVD or APCVD), although the use of atmospheric pressure results in the need to use high temperatures to make the precursors volatile, which is a risk due to both the volatility and possible toxicity of such precursors.

Another type of Chemical Vapor Deposition (CVD) technique known in the state of the art is AACVD (Aerosol Assisted Chemical Vapor Deposition). This technique relies on the ability to produce aerosol from a solution containing a suitable precursor, which chemically reacts on a surface, being the product of such chemical reaction deposited and hence forming the substrate or coating of interest. This is achieved by bringing the aerosol into a reaction chamber at atmospheric pressure, by means of a carrier gas, where it passes over a heated surface resulting in nucleation, reaction and growth on a surface. Compared to the conventional deposition methods, the AACVD method presents some key advantages, such as i) a wider choice and availability of precursors whose reaction products will deposit on the surface of interest, ii) simplification of the delivery and vaporization of precursors via the generation of a precursor aerosol, iii) a more flexible reaction environment since AACVD can be operated under atmospheric pressure, and iv) the possibility of precise stoichiometric control, which simplifies the synthesis of multicomponent materials.

Once the substrates or coatings have been provided, or manufactured for example via the aforementioned deposition techniques, it is possible to create patterns on the external surfaces of such substrates or coatings, in order to structure such substrates or coatings, for example with several techniques known in the state of the art. Some of these techniques with their particularities are disclosed below:

Micro-contact printing or nano imprinting: In this technique, a pattern is generated on a surface by features created in a mold which has been prepared in advance, more precisely by using a mechanical press that presses the mold onto the substrate (or coating) to be patterned or structured, which must be soft so it can be imprinted. Patterns with features as small as 10 nm can be created with this technique. However, the stamping of the features with the press has to be very precise, and the working environment can easily contaminate the substrate or coating to be imprinted.

Photolithography: This refers to techniques which use light radiation, such as visible light, ultraviolet light or X-rays, that can be used to create microstructural or nanostructural patterns in a substrate or coating of interest, by the use of a mask which is photoresistant and therefore covers the surface that is meant to be kept on the material. After the exposure of the areas of interest of the substrate (or coating) of interest, the softer parts are finally removed from the substrate (or coating) with appropriate solvents. This technique not only requires a clean environment to be carried out, but also the use of a mask and the use of solvents, and cannot be applied to create patterns on non-planar surfaces.

Electron or ion beam lithography: This technique uses focused beams of electrons or ions in order to erode the surface of interest and hence generate a structured pattern on it. This patterning process is time-consuming and inefficient, requires complex and expensive equipment, and shows difficulties to create patterns on non-planar surfaces

Point to point laser lithography: This technique uses laser light in order to erode the material of the surfaces of interest to be patterned or structured. The feature size is determined by the wavelength of the laser light used to create the features. As the name suggests, the laser beam has to be directed at each point of interest of the surface to be patterned for the removal to be eroded. Therefore, this patterning process is time-consuming and requires complex and expensive equipment.

One type of lithographic technique of interest which allows to generate structured patterns on substrates or coatings is known in the state of the art as Laser Interference Litography (LIL). This technique allows generating patterns on substrates (or coatings) by using an interference pattern of multiple laser beams, for example UV light beams, so the laser can scatter on a surface rather than on a single point. This allows fast and at the same time precise transfer of patterns with submicrometric resolution onto a substrate or coating, by eroding the surface material of such substrate or coating to be structured with the laser, without the need of a patterning mask to determine the design to be realized. In other words, the structured or patterned surface is created on an already existing substrate (or coating), by irradiating its external surface with the laser, so that the laser removes the material of interest by eroding it due to the laser energy. All in all, the conventional processes for the manufacture or structuring of coatings (or substrates) have considerable limitations, in that they are complex or time-consuming and expensive, or in that they do not allow scalability for the manufacture and structuring of bigger coatings (or substrates) at industrial scale.

Object of the invention

The present invention refers to a novel method for manufacturing products with a structured surface such as substrates or coatings, while also being able to structure such product. This method allows to manufacture a product with a structured surface in an easier and less timeconsuming manner compared to methods of the state of the art, and is also scalable. In the method according to the present invention the structuring is not carried out by eroding the surface to be structured, as it is the case for the structuring methods of the state of the art, but rather by locally controlling the areas on which deposited liquid precursors will chemically react and its solid reaction products will grow, by controlling the local temperature of the partial area/s of interest.

To do so, the method of the present invention combines the deposition on a deposition surface of an aerosol comprising at least one liquid precursor capable of undergoing a thermally induced chemical reaction in order to generate a solid reaction product, for example by means of the technique known as Aerosol Assisted Chemical Vapor Deposition (AACVD), together with local heating means which locally raise the temperature on certain areas only, promoting the growth and deposition of the reaction product on those areas only, since the deposition is driven by thermally induced chemical reactions of the liquid precursor materials. In order to do so, an aerosol comprising at least a liquid precursor capable of undergoing a thermally induced chemical reaction is deposited onto a deposition surface, and either simultaneously or afterwards heat is applied locally at least on a partial area of the deposition surface of interest to promote the thermally induced chemical reaction, in order to generate reaction products which grow on that partial area/s. The precursor product/s deposit and grow on that intended area/s of higher temperature, and hence it is possible to control according to the present invention the area/s of material deposition, as well as how much material is deposited on that area of deposition, hence controlling the structuring and thickness of the coatings or substrates as they are being manufactured. In fact, in those partial areas of the deposition surface where heat is applied and the liquid precursor reacts to form the solid product, there will be an elevation on the deposition surface caused by the deposition of the solid product on that partial area, thus creating an elevated structured surface, with respect to an area of the deposition surface adjacent to said partial area where the heat is not applied and no solid product is deposited.

The deposition surface of interest on which the at least one liquid precursor is deposited and chemically reacts to form the solid reaction products, can be located anywhere the aerosol containing the liquid precursors can reach it, preferably located inside a reactor or reaction chamber.

One embodiment of the invention contemplates a single jet, that is one point of entry for the stream of liquid precursor/s, to provide the aerosol comprising at least one liquid precursor onto the deposition surface of interest. Such aerosol also comprises a carrier gas (1) which may be any gas capable of carrying the liquid precursor and forming an aerosol.

According to another advantageous embodiment of the invention, a multiple jet system is contemplated, in which there are several points or several streams of entry, namely a plurality of inlets or jets, from which the liquid precursor/s react on the deposition surface of interest, so that their product/s are later deposited onto such deposition surface on which the material (solid reaction product) is grown. A multiple jet system helps in achieving deposition uniformity on the deposition surface of interest, as well as providing a faster deposition which can deposit higher quantities of material, all of it aiding the scalability of the deposition and structuring process according to the invention.

In order to promote the thermally induced chemical reactions on local areas of the deposition surface to be deposited, local heating means are provided capable of heating the partial area/s of interest of the deposition surface to be heated, where the growth of precursor product material is intended to be promoted. Any local heating means known in the art may be used for this purpose according to the invention. Non-limiting examples of such local heating means are local resistors, particle beams, or electromagnetic irradiation such as laser beams, infrared heating elements, etc.

Optionally, the local heating means may be combined with general heating means which are able to heat the whole area of the deposition surface to be heated, such as a heater or a furnace, in order to more easily reach the high temperatures needed for the deposition of the precursor products locally on the partial area/s of interest.

An advantageous local heating means according to the invention is to use laser irradiation, particularly a Laser Interference (LI) system adapted to the deposition of the aerosol onto the deposition surface, which provides heat locally by the use of a laser pattern irradiating the local area/s of the deposition surface of interest on which precursor product/s are to be grown, combined together with a deposition process of the aerosol onto the deposition surface, in order to manufacture the structured substrates or coatings, for example microstructures and/or nanostructures. Such deposition process may be process known as an AACVD process, which when combined with the LI system according to the invention is herein defined as LIAACVD.

The invention also contemplates the system to carry out the method of the present invention comprising at least an AACVD system and local heating means.

The invention also contemplates the product to be obtained by the use of the AACVD system together with local heating means according to the present invention. Such product may be structured coatings (for example with use as photocatalysts) or structured substrates (for example with use as filters).

All in all, the first embodiment of the invention provides a method for manufacturing a product with a structured surface comprising the steps of: a) depositing an aerosol onto a deposition surface, wherein the aerosol comprises a carrier gas (1) and at least one liquid precursor capable of undergoing a thermally induced chemical reaction to generate a solid product, and b) locally applying heat on a partial area of the deposition surface to promote the thermally induced chemical reaction, such that said partial area corresponds to an elevation of the structured surface with respect to an adjacent area of said partial area, adjacent area where the heat is not applied.

The deposition of an aerosol onto a deposition surface may be carried out by Aerosol Assisted Chemical Vapor Deposition (AACVD).

In a second embodiment of the invention, the deposition surface is located inside a reaction chamber (10) during the deposition of the aerosol and the local application of heat. In a third embodiment of the invention, the thermally induced chemical reaction is a thermal decomposition of the at least one liquid precursor, or a chemical reaction of the at least one liquid precursor with a reactive gas.

In a fourth embodiment of the invention, the at least one liquid precursor is provided by a plurality of aerosol jets.

A fifth embodiment of the invention additionally comprises heating the whole deposition surface. This heating promotes the thermally induced chemical reaction and promotes the deposition of the precursor product/s on the deposition surface.

In a sixth embodiment of the invention, the heat on said partial area is applied area by electromagnetic irradiation, in particular by laser irradiation.

In a seventh embodiment of the invention, the laser irradiation is applied by Laser Interference (LI).

In an eighth embodiment of the invention, a system for carrying out the method according to any of the previous embodiments is provided, the system comprising:

- An Aerosol Assisted Chemical Vapor Deposition (AACVD) system configured to deposit aerosol comprising at least one liquid precursor onto a deposition surface (50),

- Local heating means configured to locally heat a partial area of that deposition surface (50), particularly a laser beam or pattern (30),

- Optionally, general heating means configured to heat the whole deposition surface (50),

- Optionally, means (40) configured to move the deposition surface or the local heating means with respect to each other, and

-Optionally, control means configured to control the heat on different partial areas of the deposition surface.

In a ninth embodiment of the invention, the AACVD system comprises:

- an atomizer subsystem (5) configured to create an aerosol comprising at least a liquid precursor by using pressurized carrier gas (1). - a reaction chamber (10) subsystem configured to receive the aerosol and carry out the deposition on the deposition surface (50).

- a fluidic subsystem configured to bring the aerosol from the atomizer subsystem (5) into the reaction chamber (10).

-Optionally, a transparent window (22) configured to let a laser irradiation (30) through it into the reaction chamber (10).

In a tenth embodiment of the invention, the reaction chamber (10) comprises an inlet (7) for the aerosol (and optionally also for reactive gas) into the reaction chamber (10), and an outlet (8) configured to allow flushing out of the reaction chamber (10) gas, such as the carrier gas (1), the reactive gas, or the gases generated as side-products of the thermally induced chemical reaction which generates a solid product, or any combination of these gases.

In an eleventh embodiment of the invention, a system for carrying out the method of the invention is considered, which comprises a transparent intermediate chamber comprising the transparent window (22), wherein the intermediate chamber comprises an inlet (23) and an outlet (21) configured to inject and extract a curtain gas (16) into it, and configured to flush the transparent window (22) and let the laser irradiation (30) into the reaction chamber (10), for avoiding condensation of the liquid precursor on the transparent window (22).

In a twelfth embodiment of the invention, the AACVD system the AACVD system comprises a multiple jet delivery system configured to provide the at least one liquid precursor by a plurality of aerosol jets.

In a thirteenth embodiment of the invention, wherein the local heating means comprise a laser system, in particular a laser Interference (LI) system.

In a fourteenth embodiment of the invention, the laser interference system comprises a lens system configured to allow changing the incidence angle of the laser, onto the deposition surface on which the aerosol comprising at least one liquid precursor will be deposited.

In a fifteenth embodiment of the invention, it is considered the product with a structured surface obtainable according to the method of the invention. This product may be for example the final product on itself (substrate) or be a coating to be applied on another substrate. Description of the Figures

Figure 1 shows a diagram of a preferred embodiment according to the invention, in which the AACVD system is provided with a laser interference system as the local heating means.

Figure 2 shows a diagram of the creation of the interference pattern (interference area) on the deposition surface on which the reaction products will be generated by an AACVD system with a laser, particularly a laser interference system, as the local heating means.

Figure 3 shows two particular embodiments of an AACVD multiple jet system according to the invention, multiple jet system which is positioned inside the reaction chamber of the AACVD system and delivers the liquid precursors onto the deposition surface inside the chamber.

Figure 4 shows four micrographs (4a-4d) obtained by Scanning Electron Microscopy (SEM), for four different nanostructured coatings of Zinc Oxide (ZnO), prepared according to the method of the present invention, using an AACVD system provided with laser as the local heating means. Variable laser power of the laser beam of 5W (Fig. 4a), 5.25W (Fig. 4b), 5.50W (Fig. 4c) and 6W (Fig. 4c) was used to deposit the different products with a microstructured surface. The other parameters for the AACVD process and the laser as the local heating means, for this non-limiting example of Fig. 4, are detailed in the description.

Detailed description of the invention

The present invention refers to a novel method for manufacturing products with a structured surface such as substrates or coatings, while also being able to structure such product. This method allows manufacturing a product with a structured surface in an easier and less timeconsuming manner compared to methods of the state of the art, and is also scalable. In the method according to the present invention the structuring is not carried out by eroding the surface to be structured, as it is the case for the structuring methods of the state of the art, but rather by locally controlling the areas on which deposited liquid precursors will chemically react and its solid reaction products will grow, by controlling the local temperature of the partial area/s of interest.

To do so, the method of the present invention combines the deposition on a deposition surface of an aerosol comprising a carrier gas (1) and at least one liquid precursor capable of undergoing a thermally induced chemical reaction in order to generate a solid reaction product, together with local heating means which locally raise the temperature on a partial area/s of interest only, promoting the growth and deposition of the material on that partial area/s, since the deposition is driven by thermally induced chemical reactions of the liquid precursor/s material. The resulting solid precursor product/s deposit on that intended area of higher temperature, and hence it is possible to control according to the present invention the areas of material deposition, as well as how much solid reaction product is deposited on that area of deposition, hence controlling the structuring of the products with a structured surface, and their thickness, as they are being manufactured.

The carrier gas (1) may be any gas capable of carrying the liquid precursor and forming an aerosol, for example nitrogen (N2). A mixture of carrier gases may also be used for this purpose.

The deposition surface refers to an initial surface onto which the liquid precursor/s are deposited, before the chemical reaction of the liquid precursor/s which generates the solid reaction products on top of such deposition surface. This deposition surface may be the surface of a pre-existing sample, in which case a coating is generated on top of such sample. This deposition surface may also be a plate, such as a metallic or ceramic plate, in which case a substrate made of the solid reaction products is manufactured which can then be separated from the plate.

In fact, in those partial areas of the deposition surface where heat is applied and the liquid precursor reacts to form the solid product, there will be an elevation on the deposition surface caused by the deposition of the solid product on that partial area, thus creating an elevated structured surface, caused by the deposition of the solid product on that partial area, with respect to an area of the deposition surface adjacent to said partial area where heat is not applied and no solid product is deposited.

The deposition surface of interest on which the at least one liquid precursor is deposited and chemically reacts to form the solid reaction products, can be located anywhere the aerosol containing the liquid precursors can reach it, preferably located inside a reactor or reaction chamber. A preferred embodiment according to the invention uses for depositing the aerosol onto the deposition surface of interest, the technique known as Aerosol Assisted Chemical Vapor Deposition (AACVD), which allows to manufacture substrates or coatings in a fast and controlled manner. With the use of the AACVD process according to the invention, aerosol droplet precursors are used, and solid reaction products form and deposit on a partial area/s of a deposition surface due to the encountered local heat on the deposition surface, since the deposition occurs by thermally induced chemical reactions. The AACVD process allows to deposit material at atmospheric pressure, avoiding the use of vacuum systems, and in a uniform manner, even on non-planar surfaces. Moreover, the AACVD uses sprayed aerosols, thus avoiding the need for volatile precursors, which may also be toxic, compared to conventional Chemical Vapor Deposition processes. This allows a wide choice of precursors, including volatile and non-volatile precursors, with which the AACVD deposition process can be carried out, and hence to be able to deposit a great variety of materials. The AACVD process according to the invention also allows a good control of the material deposited or grown on the partial area/s of the deposition surface of interest, more precisely good stoichiometric control, also allowing thickness and morphology control, as well as the possibility to incorporate dopants or nanoparticles on the products with a structured surface to be manufactured and grown. Last but not least, AACVD also makes use of moderate deposition temperatures, around 200 °C, and is compatible with a great number of substrates, which makes the process easier and more energy efficient.

The liquid precursor/s which react to form the precursor product is carried by a carrier inert gas (e.g. N₂), and may also be dissolved or dispersed in a liquid solvent (e.g. ethanol) if such precursor is not liquid itself (for example ZnCI₂ in ethanol as the liquid precursor).

The selection of the type of precursors and its flow rate influences the deposition rate, thus being possible to control these parameters, among others, in order to obtain a high deposition rate which makes the process faster and allows to cover a wider area of interest with the precursor reaction products. All kinds of precursors known in the state of the art for AACVD may be used, for example metal precursors, for example precursors containing metallic Ag or Au or Zn as a non-limiting example.

The reaction product/s may be formed by the thermally induced chemical reaction of the at least one liquid precursor with a reactive gas. All kinds of solid reaction products resulting from thermally induced chemical reactions of liquid precursors are considered according to the invention, for example chemical reactions such as the thermal decomposition of a liquid precursor into a product or a chemical reaction of the reaction product with a reactive gas.

The reactive gas may be on the atmosphere itself or be provided externally. One example of reactive gas would be oxygen, either atmospheric oxygen or externally provided oxygen of any purity, which may react with liquid precursors in order to create solid deposited oxides on the partial area/s of interest. A non-limiting example of such reaction between a liquid precursor and a reactive gas, would be the reaction between the liquid precursors zinc chloride, zinc acetate, or zinc acetylacetone, with oxygen (O2), in order to create and deposit the reaction product ZnC>2. Another non-limiting example of a reactive gas would be the use of externally applied N2 as the reactive gas, for reaction with certain metals contained within the liquid precursor aerosol, in order to form stable nitrides as the reaction products (e.g. OSN2, Irish, PtN₂, etc.).

The reaction product/s may also be formed by the thermally induced decomposition of the liquid precursor into the reaction product. A non-limiting example of such decomposition is the use of AuCk precursors which thermally decompose into Au (gold), hence depositing Au as the solid precursor product.

A combination of any type of liquid precursors may be used to generate products with a structured surface of any composition, by the deposition process and thermally induced chemical reactions of the liquid precursors according to the invention.

In the case that the deposition surface of interest is located in a reaction chamber, after the reaction products have been generated, the carrier gas (e.g. N₂) as well as the gas side products from the chemical reaction/s (e.g CI2 gas resulting from the reaction of ZnCh with O2 to generate ZnO) are exhausted from the reaction chamber, for example with a valve system as can be seen in the gas outlet 8 comprising a valve 9 in Fig. 1.

Also after the reaction product/s have been deposited on the deposition surface of interest, and the product with a structured surface has been manufactured, the liquid solvent, or liquid precursors remaining on the unreacted regions which have not been locally heated and hence have not generated a solid product, are finally removed from the deposition surface and the surface of the structured product by any removal means known in the state of the art, such as drying or wiping them clean. If the deposition surface of interest was located inside a reaction chamber, it may be necessary to remove the sample from that reaction chamber to remove these liquid remnants.

The result of the application of the method is the creation of a product with a structured surface with precursor reaction products deposited only on the partial area/s which have been locally heated, which produces elevations on that partial area, with respect to the adjacent areas where no or little deposition of reaction precursor products occurs because they have not been locally heated.

The microstructure generated on the product with a structured surface (referred to the grain shapes and sizes of the reaction products as can be seen in the SEM micrographs of Figure 4 for the reaction product ZnO) depends on several deposition parameters, such as the locally applied temperature during the reaction of the liquid precursor/s, reaction/deposition time, aerosol quantity, and droplet size of the aerosol containing the at least one liquid precursor. It also depends on the parameters of the local heating means, such as for example the laser beam power when laser is used as the local heating means.

As for the aerosol deposition and local heating parameters, any values for the different parameters such as flow rate of aerosol containing the at least one liquid precursor (4 to 8 L/min as non-limiting examples), pressure of the atomizer which generates the aerosol, deposition time and deposition temperature (325-450 °C as non-limiting examples), etc., may be used to generate the structured substrates or coatings according to the invention.

Optionally, it is considered in the present invention to combine one or more liquid precursors in the aerosol so that the deposited solid reaction product consists of a single precursor product or a mixture of precursor products. Also optionally, more than one precursor may be applied one after the other, so that the deposited solid reaction product is a multilayer material whose layers consist of each of the precursor products deposited. Last but not least, both possibilities may also be combined, so that a multilayer whose individual layers consist of a precursor product or a mixture of precursor products may be obtained.

The aerosol containing at least one liquid precursor is preferably applied all over the deposition surface or sample surface (50) on which the reaction products generate hence generating the product with a structured surface. However, optionally a mask may be applied during application of the droplet precursors, so that the droplet precursors are not applied all over the deposition surface or sample surface (50), such that a deposition pattern can be determined by the mask.

The use of single jet AACVD is considered according to the invention. A single jet AACVD system uses only one point of entry for the aerosol comprising at least one liquid precursor which will react in the reaction chamber and ultimately provide the material (precursor product/s) to be deposited and grown onto the partial area/s of the deposition surface of interest. With the use of single jet AACVD according to the present invention, growth rates of the product with a structured surface for example of 10nm/min. can be obtained, being able to deposit areas in the range of for example square millimeters areas, for example areas of 3 mm², at deposition temperatures for example around 350 °C.

AACVD is conventionally done using a single jet AACVD in the state of the art, that is using a single jet of aerosol precursors to deposit materials on the deposition surface of interest.

According to a preferred embodiment, a novel consideration in the present invention is the use, as the means to deposit the aerosol comprising the at least one liquid precursor, of an AACVD system with a plurality of jets or inlets configured to apply or provide the aerosol precursors onto the deposition surface of interest, in order to deposit the reaction products and generate the product with a structured surface according to the invention; process which will be referred to as multiple jet AACVD. In other words, the AACVD system is configured to be a multiple jet delivery system in which there are several points or several streams of entry for the aerosol comprising the liquid precursor/s, through at least two different inlet points, for example into an AACVD reaction chamber.

According to this preferred embodiment of the present invention, using multiple jet AACVD allows to inject the aerosol containing the precursor/s from different positions, through several inlets or jets, and at a higher flux rate, allowing a more uniform and higher deposition rate of the precursor product/s, bigger areas to be deposited, and a higher control of the deposition process; all as compared to single jet AACVD. Hence, AACVD using a plurality of aerosol jets results in faster and higher deposition rates, allowing the deposition process to be scalable at large capacity.

Moreover, the preferred embodiment of the AACVD system, in which a multiple jet system is used in an AACVD reaction chamber according to the invention, makes it possible to generate structured substrates or coatings, down to nanometric resolution, with conformal and uniform deposition at high growth rates and over large areas. This is achieved thanks to the faster and broader material deposition possible with the AACVD multiple jet system of the present invention, for example with deposition rates up to 10 nm/min covering deposition areas in the range of squared centimeters, for example 10-50 cm², and being possible to deposit the material at temperatures of 200 °C or lower. All these characteristics of the multiple jet system allow the upscaling of the deposition and product structuring process according to the invention.

In a preferred embodiment according to the invention, the AACVD multiple jet system is configured in a way that the ejected aerosol may cover the whole area of the deposition surface, wherein at least one of the jets is preferably located on top of the deposition surface on which the aerosol is deposited, more preferably all of the jets being located on top of that deposition surface. A non-limiting example of such distribution for the AACVD multiple jet system can be seen in Fig. 3.

The novelty of the present invention lies in combining the deposition of an aerosol on a deposition surface as previously described, together with local heating means which are able to heat a partial area/s of the deposition surface of interest locally. The local heating will promote the deposition of the precursor product/s on that intended particular area/s, since the products form from thermally induced chemical reactions. And in said partial areas where the solid reaction products form there is an elevation with respect to the adjacent areas where solid reaction products do not form. Hence, this allows the precise creation of products with a structured surface (e.g with microstructures or nanostructures) by controlling the local heating of the partial areas. This combination also allows precise tailoring of the morphology, and the inclusion of surfactants or nanoparticles in the deposited solid products by including them in the precursors, which will also influence the morphology of the product with a structured surface, such as coatings or substrates.

Any local-heating means which allow to heat areas of the deposition surface locally and control the heat of those areas locally may be used according to the present invention. As a nonlimiting example, locally placed resistors may be used, or particule beams, or electromagnetic irradiation such as lasers or infrared beams which may act locally, etc; or their combination. Optionally, control means of the local heating means can also be provided, which allow to control how much heating is provided on different partial areas of the deposition surface, for example by controlling one or more heating means independently. In the case that there are a plurality of heating means, the control means can independently turn them on off to provide heat or not. For example, a control unit may be used for this purpose, configured to control the heating provided by each of the local heating means. Such control unit may regulate the heat provided by each heating means automatically or manually with the input provided by an operator.

Optionally, the local heating means may be combined with general heating means which are able to heat the whole area of the deposition surface to be heated on which the material grows, such as a heater or a furnace, in order to more easily reach the high temperatures needed for the thermally induced chemical reactions which result in the deposition of the precursor product/s. Since the local heating means are still present, higher temperatures can still be achieved in a controlled manner for the partial areas of interest of the deposition surface where the reaction products deposit and form elevations, as compared to the remaining areas of the deposition surface where reaction products are not generated because no local heat is applied.

Therefore, the combination of the deposition of an aerosol comprising liquid precursors, for example according to the AACVD process, together with local heating means, provides a completely new approach to grow structured coatings or substrates, which allows to locally determine the partial area/s of a deposition surface where the precursor product/s deposit, since the local heat promotes their deposition on that particular local area. This allows the precise tailoring of three-dimensional structures, such as microstructures and nanostructures, on the surface of the products with a structured surface as they are being manufactured. Another advantage of the local heating is that the whole sample does not need to be heated as it is conventionally required by the AACVD technique, being enough to heat it locally, which does away with the need to heat the whole sample, with the corresponding lower energy consumption and higher control of the deposited material locally, according to the present invention.

A preferred embodiment of the present invention is to use laser irradiation, particularly the technique known as Laser Interference (LI) as the local-heating means, together with the deposition process known as AACVD, in order to create the structuring on the products which are being deposited, for example microstructures and/or nanostructures. This combination of LI and AACVD was herein defined as LIAACVD, and non-limiting examples of them can be observed in Figures 1 and 2.

Any laser parameters capable of generating local heating on an incidence area may be used, such as for example any wavelength, pulse duration, or laser power. These laser parameters refer to any kind of laser used for local heating, such as ordinary laser beams as well as laser parameters for the Laser Interference (LI) technique. As non-limiting examples, possible ranges for these laser parameters are a laser wavelength of 300-1500 nm, a pulse duration of 0.1-100 nm, and a laser power of 100-1000 mW. In fact, the laser wavelength of 300-1500 nm is advantageous according to the present invention as it allows to create nanostructuring with features smaller than 1 .m, as compared to higher wavelengths of the laser beam which result in broader structuring features.

Note that the use of a deposition process of aerosol as previously described onto a deposition surface (such as AACVD), promoted by local heating means such as laser (for example Laser Interference), both combined in order to generate products with a structured surface, according to the present invention, is very different from the conventional generation of structures by Laser Interference Litography (LIL).

This is because the use of laser as the local heating means, according to the present invention, is used in order to grow areas locally by providing local increments in temperature on partial areas of the product with a structured surface to be manufactured. In contrast, conventional LIL lithography structures a sample by removing the external material, in particular areas of the sample, instead of promoting the growth of the deposited precursor products on partial areas, as in the present invention. In fact, the specific embodiment combining laser such as Laser Interference (LI) as the local heating means, with AACVD, according to the present invention, requires less processing time and provides higher control of the structuring, without the need of a mask, in contrast to conventional LIL lithography which is in fact based on a different mechanism, namely material removal at the external surface, instead of controlling the growth of material on the deposition surface by promoting the deposition of solid reaction products on partial areas of such deposition surface as in the present invention.

In a preferred embodiment of the invention which combines laser (particularly LI) and AACVD (namely LIACCVD), the invention allows to determine with the laser the precise areas on which the deposits will grow, since the laser interference determines a pattern which irradiates and heats the precise partial areas of interest to be grown on the deposition surface, heating that area and promoting the thermally induced chemical reaction of the liquid precursors, hence depositing the solid products on that area. In this manner, the areas of incidence of the laser (or laser pattern) will determine the growth areas, whereas the areas where the laser (or laser pattern) is not applied will determine the no-growth areas on the coating or substrate where no or little precursor products are deposited by AACVD. Therefore LIAACVD allows, by the aforementioned mechanism, to create precise products with a structured surface as these are being manufactured. The LI generates an interference pattern of multiple laser beams that can be applied during deposition of the solid reaction products, areas which will show elevations with respect to the areas where no local heating is applied, hence allowing flexible design of the structuring. In fact, it is possible to create products with a structured surface with details at any resolution, even down to micrometric or nanometric resolution.

According to the abovementioned preferred embodiment LIAACVD of the present invention, precision laser interference optics and state of the art pulsed lasers (LI) can be integrated with large area AACVD reaction chambers (or reactors) producing highly ordered concentrated light patterns on the deposition surface of materials, with a pitch of fractions of the laser wavelength that result in a highly tailorable surface structuration, for example allowing to generate microstructured or nanoproducts with a structured surface.

The preferred particular use of laser (particulary LI) for locally heating the partial areas of the deposition surface onto which the solid precursor products are to be grown by AACVD (namely LIAACVD), has been found very advantageous according to the invention, since it provides during deposition by AACVD high adaptability of the structures to be grown or deposited without the need for a mask of any kind, neither a photomask nor a thermal mask, and with high precision so that the features can be grown into the substrate or coating in a precise manner. This particular embodiment of the invention, combines the AACVD chemical deposition technique which deposits the product (substrate or coating), with the simplicity of structuring by laser (particularly LI). In summary, the LIAACVD system of the present invention allows to create structures with high resolution patterns or features down to nanometric resolutions (< 1 pm) while generating products with a structured surface in a simple and scalable manner, in a single-step process, with high flexibility in the pattern design, and without the need of a mask in contrast to other conventional lithographic techniques. According to a preferred embodiment of the invention, any feasible parameters may be used to carry both the deposition system (for example by AACVD deposition) and the structuring using laser as the local heating means.

A non-limiting example of the AACVD parameters would be for example to use as the aerosol precursor ZnCh dissolved in ethanol, for example 0.4-0.8 g of ZnCl2 dissolved in 40mL of ethanol, and apply it as an aerosol generated by the aforementioned liquid atomized by a gas (e.g. N2 or Ar), at an atomizer pressure of 1.5 bar, which is applied with a flow rate of 6 L/min, with local heating up to 350 °C of the partial areas where the deposition of the reaction product (e.g. ZnO) is to be promoted. According to this non-limiting example of application of the AACVD process, the full-deposition of the ZnO oxide is carried out, by thermally induced chemical reactions within the reaction chamber between the precursor ZnCl2 and atmospheric or externally applied oxygen (O2), reaction promoted by using laser as the local heating means, in order to generate the substrate or coating of interest.

A non-limiting example of the laser parameters which may be applied for the AACVD as the local heating means according to the present invention, would be to use laser/s of 0,6 mm beam diameter, with a power of 5-6W (namely 5W, 5.25W, 5.5W and 6W), a pulse duration of 200 ns, a pulse frequency of 100 kHz, and a wavelength of 1064 nm.

For the particular non-limiting example of the AACVD method according to the invention which uses laser as the local heating means, when using the AACVD parameters and laser parameters disclosed above, after a one hour deposition of the ZnO solid precursor products on the partial areas of interest, a microstructured coating of ZnO can be obtained with structured features smaller than 1 pm (see SEM micrographs of Figure 4).

The system to carry out the invention comprises therefore an AACVD deposition system with its corresponding reaction chamber (this system will be referred to as the AACVD system) configured to deposit material onto a deposition surface, as well as local heating means (e.g. laser/s) in order to locally heat particular areas of the deposition surface on which the material is to be grown by the AACVD deposition within the reaction chamber.

Such heating means may be local resistors, particle beams, or electromagnetic irradiation such as laser beams, infrared heating elements, etc.; or their combination. An example of radiation beams are laser beams. In this case, the laser system that provides the local heating is preferably located outside of the reaction chamber of the AACVD system.

In a preferred embodiment of the system according to the invention, the local heating means comprises at least a Laser Interference system (LI system), which may be combined with the aforementioned heating means.

A non-limiting example of application of the LIAACVD method, in order to generate a structured substrate or coating according to the present invention, is presented below.

Figures 1 and 2 shows a preferred embodiment according to the invention, in which the AACVD system is provided with a laser interference (LI) system as the local heating means of the deposition surface, onto which the solid precursor products shall be deposited by AACVD deposition.

In figure 1 , for the AACVD system, the input and output of material flows can be observed, as well as the subsystems which the AACVD system comprises which are at least one atomizer (5) to generate an aerosol with the precursor material/s, at least a fluidic system (conduct from 6 to 7) to bring the aerosol into the AACVD reaction chamber (10), and the AACVD reaction chamber (10). In Figure 2 it can also be observed means configured to move the deposition surface with respect to the heating means (e.g. laser in Fig. 2), namely a stage (40) inside the reaction chamber which allows movement of the deposition surface in at least the 2 spatial coordinates X-Y, preferably on all coordinates X-Y-Z, on which the irradiated deposition surface or sample surface (50) with the interference laser area (30) is located. This allows the movement of the deposited surface with respect to the local heating means such as laser irradiation. Also analogously contemplated are means configured to move the local heating means with respect to the deposition surface.

Figures 1 and 2 show a laser interference system (11) as the local heating means of the deposition surface onto which solid reaction products are to be deposited in an AACVD reaction chamber, located externally to that reaction chamber (10), and with a lens system (elements 12 to 15) for generating the laser interference pattern (30) which will locally heat the areas of the deposition surface or sample surface (50) onto which the reaction products will deposit and grow. Both the AACVD system and the Laser Interference system (LI), together with their components, will be explained in more detail below.

This laser interference system (LI) which provides the local heating of particular areas of the deposition surface on which the material is deposited according to the AACVD technique, may be integrated within the reaction chamber of the AACVD system, or it may be externally positioned from the AACVD reaction chamber in a way that the laser is able to enter the reaction chamber, and hence able to locally heat the deposition surface of interest within the AACVD reaction chamber (10), as is the case in Figures 1 and 2.

In the case that the laser interference system is positioned outside of the AACVD reaction chamber (elements 11-15 of Figures 1-2), which has the advantage of not interfering with the AACVD deposition process inside the chamber (10), the laser penetrates the reaction chamber from the outside, for example by getting through a window or top view port on the reaction chamber which is transparent to the laser beam or radiation (for example 22 in Fig. 1), for example a transparent window made of plastic, glass or quartz.

The preferred embodiment for the system according to the present invention comprises at least two main systems, which are the AACVD system and the LI system.

AACVD system: The AACVD system may consist of at least three subsystems: mainly at least one atomizer (5), possibly 2 atomizers, wherein the solution containing the precursors (e.g. ZnCh) and a solvent (e.g. ethanol) are atomized by means of a gas such as N₂ (mixture to be atomized emanating from (1) in Figure 1), a fluidic circuit from and through which the atomized aerosol is carried by the gas onto a reaction chamber (conduct comprising elements 6, 7 in Figure 1 which reaches reaction chamber 10), and the reaction chamber itself (10 in Fig. 1) with substrate temperature control where the growth process takes place by the thermally induced chemical reaction by the laser interference pattern (30 in Fig. 2) on the deposition surface or sample surface (50 in Fig. 2). Optionally an initial circuit may also be present which brings the precursors, solvent, and carrier gas from its original source to the atomizers (for example conduct comprising elements 1 , 2 and 3 and 4 in Fig. 1).

The three subsystems of the AACVD system serve the following purpose: the atomizer (5) is where the aerosol is generated, the fluidic subsystem (circuit from 6 to 7 which reaches the reaction chamber 10) is where the aerosol flows, and the reaction chamber (10) is where the deposition of the precursor products takes place. In the following paragraphs non-limiting examples of an atomizer subsystem, a fluidic subsystem, and a reaction chamber subsystem according to the invention, are presented.

Atomizer subsystem (5 in Fig. 1). The atomizer subsystem creates an aerosol from a liquid precursor by using a carrier gas (1) or pressurized gas such as N₂, aerosol which will be later injected into the AACVD reaction chamber (10). The atomizer may consist of an aerosol generator (UGF 2000 from PALAS GmbH) that nebulizes liquids by means of an atomizer nozzle. It is connected to a gas supply (e.g. N₂ in (1)) with a gas gauge such as a quick gauge (2), gas which goes through the system generating aerosol droplets. Generated aerosol droplets reach the heated substrate being carried by the inert gas (e.g. N₂), so that the deposition of the liquid precursors on the deposition surface or sample surface (50) takes place. The atomizer needs to be calibrated in pressure and concentration, which can be done internally but also externally from the atomizer, for example by pressure precision regulators 2 and 3, and valve 4, located before the atomizer; or additionally after the atomizer by other elements such as a three-way valve 6 or a gas inlet 7 (which may comprise a valve or not) for entry of the aerosol comprising the at least one liquid precursor and the carrier gas (1) towards the reaction chamber 10; or by any other combination of conventional means. This allows calibrating the aerosol flow rate and concentration, as well as the aerosol droplet size which will influence the resulting microstructure of the product with a structured surface to be obtained, so that the best aerosol conditions for the later deposition on the deposition surface can be tailored. Regarding the selection of the atomizer (5), several aspects such as the compatibility of the precursor with the atomizer or the amount of the flow rate of the aerosol must be taken into account. When a big size reaction chamber (10) is used, a high flow rate of aerosol is necessary in order to have a laminar flow in the reaction chamber and a homogeneous deposition in consequence. Optionally, more than a single atomizer (5) may be used to create the aerosol from the liquid precursor/s, according to the atomizer subsystem of the present invention.

Fluidic subsystem (conduct from the atomizer (5), comprising elements 6 to 7, until reaction chamber 10, in Fig. 1): The fluidic subsystem may be a non-permeable conduct or tube which brings the aerosol from the atomizer (5) to the reaction chamber (10) where the aerosol precursors will eventually deposit on the deposition surface or sample surface (50). This tube may be of any diameter, for example an 8mm diameter tube. This conduct may comprise flow regulation elements such as any combination of elements 2 to 7 previously defined. Even if the particle size of the aerosol is not much influenced by the transportation through the tube, the tube may be designed to be preferably straight without curves, and alternatively be designed to be as short as possible, namely no longer than one meter, in order to avoid condensation or deposition of aerosol droplets on the tube, with the subsequent aerosol loss which results in waste of precursors, and the subsequent tube clogging problems (not shown in figures). The fluidic subsystem environment is preferably at room temperature in order to avoid any kind of condensation of the precursor in the inner part of the tube. The flow rate of the aerosol through the tube may also be measured, so that it is known for the atomizer and reaction calibration subsystems calibration. These conditions also apply for the optionally initial circuit (conduct comprising elements 1 , 2 and 3 and 4 which reaches the atomizer 5, in Fig. 1).

Reaction Chamber subsystem (10 in Fig. 1). Any reaction chamber suitable to receive the aerosol comprising the at least one liquid precursor and to carry out the deposition process according to the invention may be used as the reaction chamber (10). As a non-limiting example, the reaction chamber may be a cylindrical chamber with dimensions of 200-400 mm in diameter and 60-100 mm in height, made of steel such as stainless steel. The reaction chamber also has at least one inlet (7) for injecting the aerosol comprising at least one liquid precursor product, which also comprises a carrier gas (1). The reaction chamber may also have at least one inlet to introduce reactive gas (e.g. 02) which may be introduced externally into the reaction chamber. An option is that inlet 7 is used to introduce both the aerosol and the reactive gas. The reaction chamber subsystem may also have at least one gas outlet (8) in order to flush out the present gases in the reaction chamber (10) such as the carrier gas (1), the reactive gas, and the gases generated as side products of the thermally induced chemical reaction of the at least one liquid precursor; or any combination of these gases. Such gas outlet (8) may be equipped with a regulating valve system (9).

The reaction chamber (10) may have a transparent window or top view port (22 in Fig. 1), through which the externally located laser emits laser irradiation (e.g. a laser beam or laser pattern) which goes through that window (22) and enters into the reaction chamber (10), which may be a window made of a laser transparent material such as glass, plastic, or quartz. This window or top view port (22) can be made for example from quartz GE (ref GE214) or Quartz Heraeus (ref HSQ300) or equivalent, and have any dimension, for example 100-300 mm in width or diameter if it is round, which allows the transmission of all types of wavelengths, preferably laser wavelengths in the range 300-1500 nm, even more preferably wavelengths of 355 nm, 532 nm or 1064 nm. Additionally a heater may also be used which allows heating the whole deposition surface or sample surface (50), in order to increase its temperature faster and induce the thermal reactions which generate the deposited solid precursor products faster. Any heater or furnace suitable for this task may be used, for example a heater made of silicon nitride and able to reach 400°C (not shown in figures). The temperature may be controlled by any temperature control means known in the art, such as for example thermocouples, for example by measuring the temperature on the surface on which the deposition surface rests. The reaction chamber may also comprise a cooling system, such as a water cooling system, in order to provide a better control of the temperature, either on the whole deposition or sample surface (50), or locally in the partial areas of such surface (not shown in figures). The reaction chamber (10) may also be compatible with vacuum or high pressure, so that the deposition process according to the invention can be carried out under pressure if needed. The reaction chamber may also optionally be equipped with a gas inlet (23) and a gas outletwith a regulating valve system (21), for injecting and extracting a curtain gas (16) which may be for example an inert gas (e.g. N2). Such injection system may also comprise a curtain gas flow regulation system, for example a conduct comprising pressure regulators and a gauge (17) as well as flow valves (18, 20) and a flow meter or carrier gas (16) flow measuring system (19). The role of this curtain gas 16 (e.g. N2) is to flush the window or top view port (22) through which the externally located laser beam gets into the reaction chamber (10), so that possible condensation or clogging of the liquid precursor/s on the transparent window or top view port (22) is avoided, so that passage of the laser beam through that window (22) can be ensured into the reaction chamber (10) without any distortions. In this case, In this case, window (22) on the reaction chamber (10) would be in a different compartment of the reaction chamber (10) through which the curtain gas (16) flows, both in (23) and out (21), which is physically adjacent and separated from another compartment of the reaction chamber (10) through which the aerosol comprising the at least one liquid precursor and the carrier gas (1), namely the aerosol, flows in (7) and out (8) of the reaction chamber (10)... In this way, the curtain gas (16) does not mix with the aerosol and carrier gas (1), since they are on different compartments. Preferably, the compartment of the reaction chamber on which the window (22) is located and through which the curtain gas (16) flows is placed right above, adjacently and physically separated, from another compartment of the reaction chamber through which the carrier gas (1) flows.

Optionally, the reaction chamber subsystem is provided inside with a stage (40 in Fig. 2) configured to move the deposition surface on which the aerosol is deposited in at least the two spatial directions X and Y, or even in the three spatial directions X, Y, Z. This provides a further control of the local areas of deposition of the material on the deposition surface (50 in Fig. 2), by moving them both with respect to the local heating means when such local heating means comprise at least a laser beam or pattern, as well as with respect to the aerosol jet or jets of the deposition system. All in all, this allows to control in a more precise manner both the speed and the quantity of solid products deposited on each local area of the deposition surface of interest on which the solid products are intended to be deposited. Moreover, the flexibility in all two (X, Y) or three spatial directions (X, Y, Z) also allows precise deposition and structuring on non-planar deposition surfaces.

A preferred embodiment according to the AACVD deposition system of the present invention, corresponds to an aerosol multiple jet delivery system which allows to deliver the precursor material/s (in the form of an aerosol) onto the whole area of the deposition surface on which the solid products will be generated and grow. A non-limiting example of an aerosol multiple jet delivery systems are shown in Fig. 3, which is a multiple jet delivery means comprising a circular tubing with a plurality of orifices from which the aerosol may be ejected, and with an empty space on the inner part surrounded by the circular tubing. This multiple jet delivery means may be located on top of the area onto which the aerosol will be deposited, in which case the irradiation means which provide the local heating, for example laser beams or patterns used as the heating means, are able to impact the deposition surface onto which the solid reaction products shall be deposited, deposition surface located below the tubing (see Fig. 3), in order to heat the partial areas of the deposition surface locally. Another non-limiting example of a multiple jet delivery system could be for example a single tube with a plurality of perforations to eject the aerosol, transversally located along the length of the deposition surface, such that the whole area of the deposition surface can be covered with the aerosol, while the irradiation beam (e.g. laser beams or patterns) used as the heating means can find empty spaces around the single tube which make it possible for the irradiation beam to impact the deposition surface, in order to locally heat partial areas of such deposition surface.

The LI system may consist for example of at least one 300-1500 nm nanosecond pulse laser (11), for example of wavelength 355nm, 532 or 1064 nm, with a pulse frequency up to 500 Hz, and with a transition stage (40) as the means configured to move the deposition surface, which is movable on at least two spatial directions X and Y (preferably on the three spatial directions X-Y-Z), with a laser interference subsystem (12-15) based on diffractive beam splitters and a lens structure for the generation of 2-3-4 beam interference patterns. A non-limiting example of the parameters to be used for this laser interference subsystem is to use a 3-laser beam configuration with the following parameters: a power of 666 mW, with a laser frequency of 500 Hz, a laser pulse length of 16.9 ns, a laser beam diameter of 3 mm and a wavelength of for example 355 nm, 532 nm or 1064 nm. Conventional laser/s may also be used instead of a laser interference system.

This laser interference system (LI) which provides the local heating of partial areas (30) of the deposition surface or sample surface (50) on which the material is deposited according to the invention, may be integrated within the reaction chamber (10), or it may be externally positioned from the reaction chamber (10) in a way that the laser is able to enter the reaction chamber (10) and hence able to locally heat the deposition surface or sample surface (50) of interest within the reaction chamber (10), for example through a window or top view port (22).

This laser interference (LI) system may optionally comprise an interference setup (11-15) designed, fabricated and integrated within the reaction chamber (10) of the deposition system.

This laser interference (LI) system may also comprise an optical system in order to direct the laser beam/s or pattern onto the deposition surface (50) to be heated locally on partial areas, such as the optical system of Fig. 2 as a non-limiting example. This non-limiting example of an optical system according to Fig. 2 comprises a mirror (12), a Diffractive Optical Element or DOE (13), a lens (14) and a focal lens (15). The DOE (12) may consist for example of a diffractive splitter of 2x2 beams, which for 1064 nm laser beams deflects each beam 20° from the optical axis. The material of the DOE may be fused silica with for example a thickness of 1.15 mm and an active area of 4mm in diameter, for example fabricated by electron-beam lithography and subsequent reactive ion etching. This DOE (12) may comprise an anti- reflective coating, which may be applied on its front and/or rear surface.

In the non-limiting optical system according to Fig. 2, the DOE splits the laser beam into four beams, which are collected by two plano-convex spherical lenses (14 and 15) to reduce aberrations in the interference spot. In order to obtain the interference pattern (30), the optical paths between the beams must be smaller than the spatial length of the laser pulse. The use of the optical elements of the optical system according to Fig. 2 provides the advantage that the difference of the length of the path can be minimized. Moreover, the period of the structures depends on the input angle of the laser beams into the interference plane, which is why the lens system settings allow changing the input angle of the laser beam, namely the incidence angle of the laser onto the deposition surface (50) on which the solid products are deposited by the deposition system. As a non-limiting example, using focal lenses (14, 15) of 65 mm and 100 mm respectively, the input angle of the laser beam is approximately 30°. This allows to control the laser pattern formed by the laser interference technique, and hence to control the local areas of the deposition surface or sample surface (50) on which the solid precursor products shall be deposited and grow.

A preferred embodiment of the invention combines the AACVD system with the LI system, which is defined as the LIAACVD system. The AACVD and LI systems using the parameters described above, as the combined LIAACVD system, allow to obtain a wide array of products with a structured surface, such as substrates or coatings. A non-limiting example of such substrates or coatings obtained by LIAACVD are films with a surface of microstructured ZnO produced from ZnCh aerosol precursors, of thicknesses up to 0,1-1 pm, with nanostructured features which can vary in size according to the parameters used for their deposition.

For example, Figure 4 shows four micrographs (4a-4d) obtained by Scanning Electron Microscopy (SEM), for four different nanostructured coatings of Zinc Oxide (ZnO), prepared according to the method of the present invention, using the AACVD deposition system provided with a laser system as the local heating means, as a non-limiting example. The coatings were deposited by AACVD deposition using the parameters previously defined in the non-limiting example corresponding to Fig. 4, with aerosol precursor flow rates comprising ZnCh of 6 L/min (see Fig. 4).

For this non-limiting example of Figure 4, the thermally-induced chemical reaction which results in the deposition of the precursor products ZnO on the deposition surface was induced by laser as local heating means, locally reaching temperatures of the partial areas of ZnO deposition of 350 °C, deposition of ZnO thermally induced by the laser for 1 h for all the coatings of Fig. 4 (Fig. 4a-4d), with the laser parameters previously defined in the non-limiting example corresponding to Fig. 4, for variable power of the laser beam of 5W (Fig. 4a), 5.25W (Fig. 4b), 5.50W (Fig. 4c) and 6W (Fig. 4c).

The elevations of the structured surface of the products with a structured surface of Fig. 4, which in this case correspond to the solid ZnO grains that grow onto the deposition surface, can be seen as brighter partial areas on the micrographs, with respect to the darker adjacent areas. It can be observed in Fig. 4 grain sizes of ZnO only deposit on the partial areas locally heated by the laser, and that with increasing laser beam power a higher area of ZnO grains is deposited on the deposition surface. The resulting ZnO microstructures may be used for example as a photocatalyst, for example in gas sensors or bactericidal surfaces.

All in all, as for the products with a structured surface which may be obtained with the novel method of the present invention, namely the combination of aerosol deposition on a deposition surface, together with applying heat locally on partial areas of the deposition surface with local heating means, it is possible to obtain products with a structured surface, with a wide array of structure morphologies and compositions.

These products with a structured surface obtainable according to the invention may be patterned coatings, which may be used for example as photocatalysts. A wide variety of photocatalysts may be produced, for a wide variety of applications such as energy applications (for solar cells, for solar oxide fuel cells, for water splitting, etc.), environmental applications (for reduction of CO2 into fuels or chemicals, for degradation of pollutants, NO2 sensors, etc.) or medical applications such as bactericidal surfaces. Non-limiting examples of the material composition of these photocatalysts are Indium tin oxide (ITO), Yttria stabilized zirconia (YSZ), Gadolinia-doped ceria (GDC), sulphur-doped Indium, doped TiO2, ZnO, ln₂O3, SnO2, GaN:ZnO, Pt/WOs, CeO2, Bi2Ss, or their combination.

These products with a structured surface obtainable according to the invention may also be patterned substrates, such as microstructured/nanostructured thin films, with use for example as filters.

All in all, the combination of the deposition of an aerosol as previously described on a deposition surface, for example by AACVD, together with local heating means such as LI, allows to precisely control the generation of a product with a structured surface as it is being deposited, structured surface which may contain microstructural and/or nanostructural features, providing a highly reproducible method to manufacture products with a structured surface in a single-step, and in a time- efficient and cost-efficient manner. Moreover, the use of laser (particularly Laser Interference) as the local heating means, also allows depositing of solid precursor products on wider areas of the deposition surface, and in greater quantities, making the method easily scalable, thanks to the high precision and speed in which laser (particularly Laser Interference) allows to locally heat the partial areas on which the liquid precursors are deposited, even at high scale. In contrast, deposition systems such as AACVD systems have only been produced at laboratory scale up until now, and the upscaling to an industrial process presents significant engineering challenges. Therefore, the deposition and structuring system according to the present invention, with its novel features, and capable of high scale industrial application, for example using a big reaction chamber (or reactor) and the combination of AACVD as the deposition process with local heating means such as LI, is a novelty itself.

Last but not least, this document only describes some of the embodiments of the present invention, and the person skilled in the art understands that other equivalent or alternative embodiments within the scope of the invention may also be carried out, as well as modifications which are equivalent or obvious. Therefore, the scope of the present invention shall not be limited to the specific embodiments described herein.

Claims

1. A method for manufacturing a product with a structured surface comprising the steps of: a) depositing an aerosol onto a deposition surface, wherein the aerosol comprises a carrier gas (1) and at least one liquid precursor capable of undergoing a thermally induced chemical reaction to generate a solid product, and b) locally applying heat on a partial area of the deposition surface to promote the thermally induced chemical reaction, such that said partial area corresponds to an elevation of the structured surface with respect to an adjacent area of said partial area, adjacent area where the heat is not applied.

2. A method for manufacturing a product with a structured surface according to claim 1 , wherein the deposition surface is located inside a reaction chamber (10) during the deposition of the aerosol and the local application of heat.

3. A method for manufacturing a product with a structured surface according to claims 1 or 2, wherein the thermally induced chemical reaction is a thermal decomposition of the at least one liquid precursor, or a chemical reaction of the at least one liquid precursor with a reactive gas.

4. A method for manufacturing a product with a structured surface according to any one of the preceding claims, wherein the at least one liquid precursor is provided by a plurality of aerosol jets.

5. A method for manufacturing a product with a structured surface according to any one of the preceding claims, which additionally comprises heating the whole deposition surface.

6. A method for manufacturing structured coatings or substrates according to any one of the preceding claims, in which the heat on said partial area is applied by electromagnetic irradiation, in particular by laser irradiation.

7. A method for manufacturing structured coatings or substrates according to claim 6, wherein the laser irradiation is applied by laser interference.

8. System for carrying out the method according to any one of the preceding claims, the system comprising:

9. System for carrying out the method according to claim 8, wherein the AACVD system comprises:

- an atomizer subsystem (5) configured to create an aerosol comprising at least a liquid precursor by using pressurized carrier gas (1).

- a reaction chamber (10) subsystem configured to receive the aerosol and carry out the deposition on the deposition surface (50).

10. System for carrying out the method according to claim 9, wherein the reaction chamber (10) comprises an inlet (7) for the aerosol into the reaction chamber (10), and an outlet (8) configured to allow flushing out a gas

11. System for carrying out the method according to claims 9 or 10, which comprises a transparent intermediate chamber comprising the transparent window (22), wherein the intermediate chamber comprises an inlet (23) and an outlet (21) configured to inject and extract a curtain gas (16) into it, and configured to flush the transparent window (22) and let the laser irradiation (30) into the reaction chamber (10), for avoiding condensation of the liquid precursor on the transparent window (22).

12. System for carrying out the method according to claims 8 to 11 , wherein the AACVD system comprises a multiple jet delivery system configured to provide the at least one liquid precursor by a plurality of aerosol jets

13. System for carrying out the method according to claims 8 to 12, wherein the local heating means comprise a laser system, in particular a laser Interference (LI) system.

14. System for carrying out the method according to claim 13, in which the laser interference system comprises a lens system configured to allow changing the incidence angle of the laser onto the deposition surface.

15. Product with a structured surface obtainable according to the method of any one of claims 1 to 7.