Deposition Process Based on Stencil Mask and Application to the Fabrication of Tags Supporting Multi-Functional Traceable Codes

Abstract

A chemical gas phase deposition process comprises steps of providing a high vacuum chamber, and inside the high vacuum chamber: positioning a substrate surface; positioning a mask parallel to the substrate surface, whereby the mask comprises one or more openings; adjusting a gap of determined dimension between the substrate surface and the mask; and orienting a plurality of chemical precursor beams of at least one precursor species towards the mask with line of sight propagation, each of the plurality of chemical precursor beams being emitted from an independent punctual source, and molecules of the chemical precursor pass through the one or more mask openings to impinge onto the substrate surface for deposition thereon. At least a part of the chemical precursor molecules decompose on the substrate surface at a decomposition temperature. The process further comprises adjusting a temperature of the substrate surface greater or equal to the chemical precursor molecule decomposition temperature, thereby remaining greater than a mask temperature, and maintaining the mask temperature below the decomposition temperature, thereby causing a decomposition of the chemical precursor and a growth of a film on the substrate surface, but not on the mask; and heating the substrate surface using a heating device.

1 . A tag device comprising a multi-functional material thin film, comprising a plurality of structures that provide a plurality of independent physical quantities, each of which is patterned to the intent of being measured by one or more measuring techniques, wherein each of the plurality of structures exhibit a specific signal in response to a selected measurement technique, wherein each of the plurality of structures has an outer size in the order of nanometres to centimetres. 
     
     
         2 . The tag device of  claim 1 , wherein the plurality of structures comprises a plurality of three-dimensional (3D) structures of different thickness and sizes, wherein each of the plurality of 3D structures displays a plurality of varying properties depending on the chemical composition, size, shape or interface combinations of heterostructures. 
     
     
         3 . The tag device of  claim 2 , wherein the three-dimensional (3D) structures are 3D dots, wherein each dot provides hundreds of different values. 
     
     
         4 . The tag device of  claim 2 , wherein said varying properties are at least one of: colour iridescence, reflectivity, light scattering, wettability, electrical conductivity, piezoelectricity, ferroelectricity, magnetism. 
     
     
         5 . The tag device of  claim 1 , wherein structures having size at different scales are present on the same tag. 
     
     
         6 . The tag device of  claim 1 , wherein the multifunctional material thin film is an oxide thin film, or a semiconductor material thin film or a ceramic thin film. 
     
     
         7 . The tag device of  claim 1  comprising a partition arranged with a plurality of regions, each region comprising structures of different sizes and/or providing physical quantities of different nature, that can be measured by different readers; wherein the tag device preferably comprises more than four regions. 
     
     
         8 . The tag of  claim 7 , wherein one of the plurality of regions has overt authentication features, one has covert anti-counterfeiting features, one has forensic anti-counterfeiting feature, one has power generation functionality, one or more regions have ultra-covert authentication features enabled by a plurality of possible reading methods. 
     
     
         9 . The tag of  claim 7 , wherein one of the plurality of regions display uniform or graded properties taken amongst the list comprising: thickness, colour and electrical conductivity, said properties being the properties of a material that are further modifiable by light irradiation or by a chemical process to achieve additional features that contribute to enhance traceability, anti-forgery or cryptographic functionalities. 
     
     
         10 . The tag device of  claim 8 , wherein the overt authentication feature is a holographic feature. 
     
     
         11 . The tag device of  claim 7 , wherein each region comprises a plurality of structures at various scales, wherein each of the plurality of regions display different functional properties that can be read through different reading techniques within the same region, wherein in each region are embedded from more than 1 up to millions of codes, preferably wherein a first region can be identified by naked eye and comprises structures having a size in the order of from millimetres to centimetres, a second region can be identified by a reader and comprises structures having a size in the order of from 10 micrometre to below 1 millimetre, a third region comprises structures having a size in the order of from 1 to 10 micrometres, and at least a fourth region comprises structures having a size in the order of from 1 nanometre to below 1 micron. 
     
     
         12 . The tag device of  claim 1 , wherein the plurality of independent physical structures are obtained by a chemical gas phase deposition process comprising the steps of:
 providing a high vacuum chamber; positioning a substrate surface inside the high vacuum chamber; positioning a mask parallel to the substrate surface, the mask including one or more openings; providing a gap of determined dimension between the substrate surface and the mask to introduce a temperature difference between the substrate surface and the mask, wherein said gap is adjustable; and orienting a plurality of chemical precursor beams of at least one precursor species towards the mask with line of sight propagation, each of the plurality of chemical precursor beams being emitted from an independent punctual source, and molecules of the chemical precursor pass through the one or more mask openings to impinge onto the substrate surface for deposition thereon, at least a part of the chemical precursor molecules decompose on the substrate surface at a decomposition temperature; and adjusting a temperature of the substrate surface greater or equal to the chemical precursor molecule decomposition temperature to remain greater than a mask temperature, and maintaining the mask temperature below the decomposition temperature, thereby causing a decomposition of the chemical precursor and a growth of a film on the substrate surface, but not on the mask, heating the substrate surface using a heating device; wherein the chemical gas phase deposition process is operated under vacuum conditions below 10 −5  mbar; wherein the substrate surface is positioned between the heating device and the mask and the distance of the mask to the substrate is smaller than the distance of the mask to the precursor sources.   
     
     
         13 . The tag device of  claim 12  obtained by the chemical gas phase deposition process in a single step. 
     
     
         14 . The tag device of  claim 12  wherein the chemical gas phase deposition process further comprises a post deposition process of laser irradiation on at least a part of the film formed on the substrate surface, thereby enabling to selectively pattern at morphological level or at the crystalline phase level. 
     
     
         15 . The tag device of  claim 12 , wherein the chemical precursor molecules are selected form the group consisting of metal alkoxides or derivatives thereof, or beta-diketone, metal alkyls; preferably wherein the chemical precursor molecules are titanium dioxide, titanium tetraisopropoxide, copper bis(2,2,6,6-tetrametyl-3,5-heptanedionate, LINbO 3 , or dimethyl zinc. 
     
     
         16 . Use of the tag of  claim 1  in an authentication process involving a step of reading the tag by naked eye or by an optical reader, said optical reader being preferably selected from the group consisting of a dvd player, a blue ray player, a Smartphone and a digital camera, whereby the tag is illuminated with a plurality of different monochromatic illumination wavelengths or with white light filtered by at least one filter, and/or by an instrument selected from the group consisting of Ohm-meter, spectral reflectometre, spectral Ellipsometre, micro-Raman, AFM, STM reader, wherein each of the reading provides a different output. 
     
     
         17 . Use of the tag device of  claim 1  in a book-cipher-like encrypting method, comprising providing at least two identical tags, which are unique and not forgeable, wherein one of the two identical tags is used as key-code. 
     
     
         18 . A packaging for a tag device according to  claim 1 , wherein the tag device is provided on a thin metallic foil sealing a container and that is torn apart when the container is open, or wherein the tag device is embedded in polymer foils, or it is directly melted into a material, or it is deposited onto an electronic device. 
     
     
         19 . The packaging of  claim 18 , wherein the tag device is melted into a material, said material being a transparent media, wherein the multifunctional thin film material is capable of withstanding high temperatures and has a high refractive index. 
     
     
         20 . The packaging of  claim 18 , wherein the tag is deposited onto an electronic device, said electronic device being a CMOS camera, a sensor or any other integrated circuit with direct vertical/monolithic integration.