ITUD20110077A1 - EQUIPMENT FOR DEPOSITION OF THIN FILMS ON A FLEXIBLE SUBSTRATE AND ITS PROCEDURE - Google Patents

Description

Description of the invention having as title:

"EQUIPMENT FOR THE DEPOSITION OF THIN FILMS ON A FLEXIBLE SUBSTRATE AND RELATED PROCEDURE"

FIELD OF APPLICATION

The present invention relates to an apparatus, and to the related process, for the deposition, according to a desired pattern or design, of thin films of metallic, ceramic, polymeric or other material, on flexible substrates by means of a continuous reel-to-reel process. , also identified as "roll-to-roll", and with technologies such as magnetron sputtering, chemical vapor deposition, also known as "CVD" or "Chemical Vapor Deposition", thermal evaporation, electron beam evaporation, or other .

In particular, the apparatus and the method according to the present invention allow the production of ceramic capacitors, electrochemical sensors, electrodes for LCD screens and in general for components with printed electronic circuitry.

Thin films are layers of material with an overall thickness of about 1 nm a few micrometers or more.

STATE OF THE TECHNIQUE

Deposition apparatuses are known which use one or more deposition sources, such as for example magnetron sputtering, thermal evaporators, effusive cells or the like.

These equipments are suitable to "evaporate" a material in the form of a block also called "target" in a process chamber to generate a flow of atoms or clusters of atoms or macromolecules which is transferred onto a substrate where it nucleates in the form of thin film.

The whole process is carried out in a high vacuum condition, ie in a low pressure environment normally between 10 <"7> mbar and 1 mbar.

The high vacuum condition allows to reduce the chemical reactions between the flow of evaporated atoms and the residual gases present in the process chamber in order to control the chemical and physical characteristics of the film that is created. Furthermore, the high vacuum condition allows to reduce the collisions between the evaporated material and the gas molecules which otherwise attenuate the energy of the flow of atoms and generate unwanted diffusion phenomena.

There are also known processes for depositing thin metal films on flexible substrates which are unwound from a reel, are subjected to deposition and rewound onto a collection reel, thus realizing a roll to roll process.

In order to define a desired pattern, the surface of the substrate on which the material will subsequently be deposited is printed in advance through the use of oils which reproduce in negative the desired pattern to be created. During the deposition phase, the flow of atoms, in correspondence with the oil, is not able to anchor itself to the substrate, thus defining the desired pattern. This solution, in addition to being rather expensive in terms of process times, has the drawback that the oils used can leave traces or residues on the substrate that could affect the final use of the product to be obtained and, in any case, require careful cleaning. of the deposited surface for their removal. Furthermore, the use of oils is not compatible with the vacuum levels to be reached inside the process chamber, even if low vapor pressure oils are used.

An apparatus for the deposition of thin films, of the roll-to-roll type, is also known which, instead of providing for the molding of oils, uses a flexible deposition mask, also called "stencil", on which a desired pattern or pattern is obtained. to be reported on the substrate. This apparatus comprises two idle rollers between which both the ribbon-shaped mask and the flexible substrate on which the material will be deposited are wound.

Specifically, the flexible substrate is unwound from a first reel, is partially wound on the two idle rollers, above the mask and, following deposition, is rewound on the downstream reel. The advancement of the substrate takes place by activating the downstream reel, which in turn determines, due to the effect of the friction that is generated between the idle rollers, the mask, and the flexible substrate, also the advancement / dragging of the mask.

In the section between the two idle rollers and on the side facing the mask, the deposition takes place by evaporation of the material.

However, this equipment has the drawback that, in the deposition section, an adequate adherence between the substrate and the mask is not ensured, leading to shading problems. In fact, in the deposition section, the mask is spaced from the substrate and the flow of evaporated atoms is deposited on the substrate, not respecting the contours defined by the mask itself and defining a non-uniform deposition profile.

Furthermore, this solution can present drawbacks of blurring of the deposited film. In fact, due to the friction necessary to advance the mask, both the substrate and the mask itself are subjected to an elastic tensile deformation.

Upon exiting the rollers, the friction between the mask and the substrate drops rapidly with consequent elastic return of the substrate and consequent phase shift and blur of the previously deposited pattern.

A further drawback of the aforementioned known apparatus is that the mask is subject, on its surface, to a continuous supply of material due to the flow of atoms which is evaporated. Over time, this contribution can modify the profile of the mask and consequently alter the shape of the deposited film. Furthermore, as the thickness of the deposited film increases, there is an increase in the internal tensions in the material which can cause both the breaking of the mask and delamination of layers. In fact, some portions of the deposited film can detach from the mask ending up on the substrate and generate surface defects.

An object of the present invention is to provide an apparatus for depositing thin films on flexible substrates which allows very precise patterns to be obtained on the substrate, defined in their contours and with a uniform deposition profile, avoiding shading and blurring problems. .

A further object of the present invention is to provide an apparatus for depositing thin films on flexible substrates which allows to avoid problems of breaking the mask or generating surface defects on the substrate which is subsequently deposited.

A further object of the present invention is to provide a method for depositing thin films on flexible substrates which allows the production of thin films on flexible substrates having very precise patterns or patterns.

In order to obviate the drawbacks of the known art and to obtain these and further objects and advantages, the Applicant has studied, tested and implemented the present invention.

EXPOSURE OF THE FOUND

The present invention is expressed and characterized in the independent claims. The dependent claims disclose other characteristics of the present invention or variants of the main solution idea.

In accordance with the aforementioned purposes, an apparatus for depositing at least one thin film on a flexible substrate to make ceramic capacitors, electrochemical sensors, electrodes for LCD screens and in general for components with printed circuitry comprises:

- feeding means and extraction means provided for moving the substrate along a given direction of advancement;

- a deposition device such as magnetron sputtering, chemical vapor deposition, thermal evaporation, electron beam evaporation, which is interposed between the feeding and extraction means, is suitable to act in a desired printing region to deposit on at least a surface portion of the substrate, which is each time included in the printing region, a thin film of material; a mask interposed between the substrate and the deposition device to determine the deposition of the thin film according to a predetermined pattern defined by the geometry of a screen which is obtained on the mask; And

- an advancement device suitable for moving the mask along the same direction of advancement according to which the substrate is moved.

According to an aspect of the present invention, the feeding device comprises holding means suitable for keeping the mask and at least the aforementioned surface portion of the substrate adherent to each other, at least in the printing region, in a direction transverse to the direction of advancement and for integrally constraining the mask and the surface portion in a direction parallel to the direction of advancement, so as to determine a movement of the mask in step with at least the surface portion of the substrate.

In this way, the holding means allow to keep the substrate and the deposition mask adhering to each other at least in the portion that is subjected to deposition by the deposition device, thus allowing to reduce shading effects and obtain a deposition profile of the thin film. uniform. Furthermore, this adherence condition must be sufficient to allow the drag of the mask and the substrate, avoiding reciprocal sliding between them and therefore problems of blurring of the same.

According to an embodiment, the holding means are of the magnetic type and, with respect to the substrate, they are arranged on the opposite side with respect to which the mask is arranged. The latter or at least a part thereof is made of magnetic iron material such as to be able to be attracted by the holding means and therefore to bring the mask and the substrate into a condition of adherence.

According to a further embodiment, the holding means comprise a magnetic bench provided with a plurality of magnetic elements arranged side by side, with respective polarities alternating with each other and defining a contact surface on which said substrate slides.

This particular configuration of the magnetic bench allows to obtain a very intense magnetic field in proximity to the contact surface and which decays very rapidly by distancing itself from it. This allows to obtain a concentrated magnetic attraction force near the mask avoiding the generation of deviant effects of the particles evaporated during the deposition phase.

In other embodiments, the magnetic elements are spaced from each other by spacer elements made of non-ferromagnetic material. This particular configuration of the magnetic bench makes it possible to reduce the occurrence of pairs of forces within parts of the screen of the mask and in the vicinity of the pole inversion areas. In fact, these pairs of forces could deform / embed the mask or its very thin parts, such as thin rods or jumpers, modifying the deposition profile of the thin film.

In another embodiment, the magnetic bench is substantially drum-shaped and on its external surface is suitable for wrapping at least partially both the substrate and the mask.

It is advantageous to provide that the magnetic bench is suitable to be rotated on itself to determine, in this way, the advancement of the substrate and the coordinated drag of the mask.

In a further embodiment, the feeding means comprise a first reel on which said substrate is wound, and the extraction means comprise a second reel on which the substrate is suitable for winding when the thin film has been deposited on it.

In another embodiment, a cleaning device, such as an ion gun or an electron gun, is adapted to remove the material evaporated from the deposition device and deposited on said mask.

In particular, it is therefore possible to remove substantially continuously the material which during the deposition step is deposited on the mask rather than on the substrate thus allowing to avoid delamination problems which could alter the geometry of the deposited pattern. The removal of this material avoids the onset of internal tensions in the parts of the mask that could make it unnerving or worse bring it to breakage. Furthermore, by means of this removal it is possible to keep the geometry of the screen of the mask unaltered, avoiding variations in the geometry of the design of the deposited film.

In embodiments, the substrate is selected from a group comprising polymeric materials, paper, synthetic fibers, or the like.

In other embodiments, the thin film is selected from a group comprising metallic, ceramic or polymeric materials.

In order to carry out a continuous deposition process of the thin film, the mask is substantially shaped like a closed ribbon and its screen is brought cyclically into contact against the portion of the substrate, near the printing region.

It is advantageous to provide that the mask comprises at least one region which has a plurality of through incisions which define a screen showing in negative the desired deposition pattern of the thin film.

In one embodiment, the mask comprises at least two successive and possibly adjacent regions having corresponding through incisions to define at least a first screen and a second screen arranged one in succession along the development of the mask and each shows a respective suitable deposition pattern to define on the substrate respectively a first pattern and a second pattern of the deposited thin film.

According to an advantageous embodiment, the apparatus further comprises deviating means suitable for making the mask follow a determined path to bring the first screen and the second screen into contact with the substrate respectively and from time to time in a first part and / or in a second part of said printing region to allow the superimposed or possibly offset deposition of said first design and said second design of the thin film.

In this way it is possible to deposit both materials that are different from each other by means of different deposition sources and to deposit on the substrate patterns with complex configurations such as empty areas presented inside the deposited areas.

The present invention also relates to the relative method of depositing at least one thin film on a flexible substrate to make ceramic capacitors, electrochemical sensors, electrodes for LCD screens and in general for components with printed circuitry: The process comprises at least one power supply phase in wherein said substrate is moved along a direction of advancement, and a deposition step in which the thin film is deposited on at least a surface portion of the substrate. A mask is associated with the substrate and the deposition device to determine the deposition of the thin film according to a desired pattern, and is moved along said direction of advance.

According to an aspect of the method of the present invention, during the movement of the mask, the latter and the surface portion of the substrate are kept adherent to each other, at least in the printing region, in a direction transverse to the direction of advancement, and rigidly constrained in a direction parallel to the direction of advancement, so as to determine a movement in step with the mask at least with the surface portion of the substrate.

ILLUSTRATION OF DRAWINGS

These and other characteristics of the present invention will become clear from the following description of a preferential embodiment, given by way of non-limiting example, with reference to the attached drawings in which:

- fig. 1 is a plan view of a substrate on which a thin film has been applied; fig. 2 is a schematic representation of an apparatus for depositing thin films on a flexible substrate according to the present invention.

- fig. 3 is a schematic representation of a first variant of fig. 2;

- fig. 4 is a schematic representation of a second variant of fig. 2;

fig. 5 is a schematic representation of a detail of fig. 2;

- fig. 6 is a schematic representation of a variant of fig. 5;

fig. 7 is a schematic representation of a detail of fig. 2 according to a variant embodiment; - figs. 8-12 are schematic representations of the deposition process with the apparatus of fig. 7.

To facilitate understanding, identical reference numbers have been used wherever possible to identify identical common elements in the figures. It should be understood that elements and features of one embodiment can be conveniently incorporated into other embodiments without further specification.

DESCRIPTION OF SOME PREFERENTIAL EMBODIMENTS With reference to fig. 1, a flexible substrate 11 is shown on which a thin film 12 of material has been deposited according to a predetermined pattern linked to particular applications.

The substrate 11 is made of a material selected from a group comprising polymeric materials, paper, synthetic fibers or the like.

The thin film 12 has a thickness between about 1 nm and a few micrometers or more, and is made of metallic material, such as a precious metal, such as gold, silver, platinum, or commonly used metal such as aluminum, copper, chromium, or in ceramic materials or polymeric materials.

The thin film 12 is deposited on a first surface 15 of the substrate 11 with evaporation techniques, selected from a group comprising magnetron sputtering, chemical vapor deposition, thermal evaporation, electron beam evaporation. Figs. 2-4 schematically show apparatuses 10, according to the present invention, for depositing thin films 12 on substrates 11 according to different embodiments.

Each of the aforementioned apparatuses 10 comprises feeding means and means for extracting the substrate 11 which in this case comprise, in turn, a first coil 13 on which a substrate 11 is wound and a second coil 14 on which the substrate 11 is wound. unwound from the first reel 13.

The first 13 and the second coil 14 are both motorized synchronously even if, in other embodiments, it is possible to provide that only the second coil 14 is motorized while on the other only the substrate 11 is unwound.

The first 13 and the second reel 14 are spaced apart by a determined distance between which a portion 16 for depositing the thin film 12 on the substrate 11 is defined.

A deposition device 17 is arranged near the aforesaid portion 16, on the side facing the first surface 15 of the substrate 11, while on the opposite side a holding means is arranged, in this case a magnetic bench 19.

The deposition device 17 is provided with a deposition source selected from a group comprising magnetron sputtering, thermal evaporators, effusive cells or the like.

The deposition device 17 exploits technologies of PVD (Physical Vapor Deposition), or CVD (Chemical Vapor Deposition) type, or methods of deposition of particles, vaporized from a surface, with a physical process of pulverization or atomization which are deposited on a support, in this case on the substrate 11.

The deposition device 17 is suitable to act in a determined printing region P which comprises at least one area surrounding the portion 16 of the substrate 11 which is brought in cooperation with the deposition device 17 itself.

In particular, during the material deposition phase at least this printing region P is subjected to a high vacuum condition, that is to a pressure between 10 <"7> mbar and 1 mbar. It is advantageous to provide that at least the deposition device 17 and the magnetic bench 19 as well as this printing region P are contained inside a vacuum chamber of the apparatus 10, not shown in the drawings.

Inside the vacuum chamber there is a filling element of the same material of which the thin film 12 is made and which is evaporated to define the thin film;

In sputtering processes the carry element is also called target and is in the form of a thin plate or disk, while in evaporation processes it is in the form of granules or wire.

In sputtering processes, a process gas, usually argon, is introduced into the vacuum chamber, which is ionized by the combined effect of an electric field and a magnetic field. In particular, the ions of the process gas by means of the electric field are accelerated towards the target and by striking against it they bring in suspension in the process gas, atoms, ions, or clusters of the target and project them towards the substrate 11 for deposition. .

In CVD processes the use of the process gas is not always required as sometimes the reaction alone is sufficient to lead to the formation of the thin film. No process gas is used in the evaporation processes, the gases present are the residual ones that the vacuum condition was unable to eliminate.

A mask 20 (Figs. 5 and 6) is arranged between the substrate 11 and the deposition device 17, and is provided with at least one region in which a plurality of through incisions 22 are obtained, defining a screen 21 and which show in negative the pattern to be deposited on the substrate 11.

In this case, the mask 20 is shaped like a closed ribbon, and can be provided with repetitive sectors showing the pattern of the screen 21. Furthermore, the mask 20 is made of metallic material even if, in other embodiments, it can be provided that only parts of it are made of metal or, by way of example only, providing substantially continuous peripheral edges made of magnetic iron material.

In order to reduce the shading effects during the deposition steps, the mask 20 has a thickness between 0.05 mm and 0.8 mm.

The magnetic bench 19 is suitable for keeping the mask 20 adherent to each other to the first surface 15 of the substrate 11, so as to ensure intimate contact between the mask 20 and the substrate 11, in all points at least in the vicinity of the portion 16, and of the printing region P, on which the thin film 12 is deposited.

With reference to fig. 2, the apparatus 10 further comprises a first roller 23 and a second roller 24, both idle on which the mask 20 is at least partially wrapped, and above the latter the substrate 11.

Specifically, the substrate 11 is unwound from the first reel 13, is wound onto the first roller 23, onto the second roller 24 and is subsequently rewound, after deposition, onto the second reel 14.

The portion 16 is defined between the first 23 and the second roller 24 which will be subjected to the deposition of the thin film 12. The first 23 and the second roller 24 allow the substrate 11 to be brought under slight tension in order to avoid dead zones thereof, they also allow to keep the portion 16 substantially aligned and parallel with respect to the magnetic bench 19.

The substantially ribbon-shaped mask 20 winds onto the first roller 23 and the second roller 24, internally with respect to the substrate 11 and is arranged substantially facing the first surface 15 of the latter.

The magnetic bench 19 by magnetic attraction puts in contact a second surface 26, opposite to the first, of the substrate 11 with a contact surface 27 of the magnetic bench 19 and respectively the mask 20 against the first surface 15 of the substrate 11.

By rotating the second reel 14, the substrate 11 is unwound from the first reel 13 and the latter advances along a direction of advancement D.

The holding action of the mask 20 to the magnetic bench 19 allows to keep the substrate 11 and the mask 20 adherent to each other and at the same time to advance both mask 20 and substrate 11 in a coordinated manner with each other and at the same pace.

The magnetic attraction force exerted by the magnetic bench 19 must be sufficient both to guarantee the intimate contact of the first surface 15 of the substrate 11 with the mask 20 in all the points placed in correspondence with the printing region P and to allow the dragging of the mask 20 with the substrate 11 avoiding reciprocal slippage. In this way it is therefore possible to reduce the shading and blurring effects of the deposited thin film 12.

On the other hand, given the very thin thickness of the mask 20, the magnetic attraction force must in any case be reduced and such as to avoid yielding, or worse, the breaking of very thin parts of the mask 20 such as thin rods and jumpers.

According to an embodiment, the magnetic bank 19 comprises a plurality of magnetic elements 30 arranged side by side, with alternating polarizations of north and south poles, in fig. 5 indicated respectively with the initials "N" and "S".

By way of example only, the magnetic elements 30 are made of Nd-Fe-B, have a parallelepiped shape and a thickness of between 2 mm and 4 mm, for example 3 mm.

According to a further embodiment, the magnetic elements 30 are magnetized in the direction of the thickness of the elements in such a way that the direction of magnetization is parallel to the contact surface 27 of the magnetic bank 19.

It is advantageous to provide that the magnetic elements 30 are positioned on a base plate 33 made of ferromagnetic material which allows the magnetic elements 30 to be kept in a well-defined position by exploiting the static friction generated by the magnetic attraction force.

In other embodiments, the base plate 33 can be made of a different material, even non-ferromagnetic, and the correct positioning is obtained by using adhesives or other fixing means.

With this configuration it is possible to obtain a very intense magnetic field near the surface and which decays very quickly by distancing itself from it. This allows to obtain a concentrated attraction force on the mask 20 avoiding the generation of deviant effects of the evaporated particles during the deposition step.

According to a further embodiment of the magnetic bench 19 (fig. 6), the magnetic elements 30 are arranged side by side, spaced from each other by spacer elements 31. In other words, the magnetic elements 30 are arranged aligned in parallel rows and oriented in so that the polarity is homogeneous along the entire contact surface 27 of the magnetic bank 19.

It is advantageous to provide that the magnetic elements 30 are equally spaced apart, by means of the spacer elements 31, by a distance equal to approximately 1.5 times the value of their thickness.

The dimensions of the magnetic elements 30 are related to the dimensions of details of the screen 21 made on the mask 20.

Specifically, the thickness of the magnetic elements 30 decreases as the dimensions of the details of the screen 21 decrease, such as for example rods, bridges which can reach very small dimensions, for example in the order of tenths of a millimeter. The spacer elements 31 are made of non-ferromagnetic material, for example of brass, aluminum, other non-ferromagnetic metal materials, or of polymeric material.

The positioning of the magnetic elements 30 and of the spacer elements 31 can be obtained in a similar way to that described for fig. 5, or by providing magnetic attraction of the magnetic elements 30 to the base plate 33 and the use of adhesives for the integral fixing of the spacer elements 31.

Or as indicated in fig. 6 providing that the magnetic elements 30 are completely embedded inside a support base 35 which defines, at the same time, also the spacer elements 31.

The solidarity of the magnetic elements 30 to the support base 35 can be further strengthened by providing for the use of adhesives.

The particular configuration of the magnetic bench 19 described with reference to fig. 6 allows to reduce the occurrence of pairs of forces inside the mask 20 and in the vicinity of the pole inversion zones. In fact, these pairs of forces can deform / embed the mask 20 or its very thin parts, such as thin rods or jumpers, modifying the deposition profile of the thin film 12.

A layer of material is inevitably deposited on the surface of the mask 20 which during use faces the deposition device 17 and is continuously removed by means of a cleaning device 37 (fig. 2) of the mask 20.

In particular, the cleaning device 37 is advantageously arranged between the first 23 and the second roller 24, advantageously in the outgoing portion of the mask 20 from the second roller 24.

The cleaning device 37 can comprise an ion gun or an electron gun which, by exploiting the sputtering principle, clean the surface of the mask 20 by accelerating charged particles against it to an energy higher than a critical value, which, for example, for gold and copper is about 20 and 17 electron volts.

The charged particles impacting against the atoms of material previously deposited on the surface of the mask 20 are expelled, providing for the cleaning of the latter.

As the kinetic energy of the particles increases, the sputtering effect increases, i.e. the depth of penetration of the particles into the material to be removed also increases, even if beyond a certain value the efficiency is reduced. For this purpose it is advantageous to provide for the use of intermediate energy values which by way of example are comprised between 50 and 3000 electron volts.

In another embodiment (fig. 3), it can be provided that on the first 23 and on the second reel 24 only the substrate 11 is wound. On two further idle rollers 40 arranged internally with respect to the first 23 and the second roller 24, at least partially envelops the deposition mask 20.

In particular, the two idle rollers 40 are arranged in such a way as to arrange at least a portion of the mask 20 which is substantially facing, parallel to and close to the portion 16 for depositing the substrate 11.

In this way it is possible to keep the substrate 11 at a controlled tension level, and it is avoided that the mask 20 is retained for example by the friction generated between the surface of the first 23 and the second roller 24 with the substrate 11.

A third idle roller 41 is arranged in an offset position with respect to the idle rollers 40 and the mask 20 is partially wound around it.

The mask 20 winds loosely on the idle rollers 40 and on the third roller 41, that is, loosely, to allow that when it passes in proximity to the magnetic bench 19 it can adapt to the latter and determine an intimate contact with the substrate 11.

To this end, in other embodiments, the idle rollers 40 can also be replaced with fixed elements such as cylinders, or pillars having the sole function of limiting the movement of the mask, preventing it from coming into contact with other parts and therefore can alter the conditions. of deposition.

The cleaning device 37 is interposed between one of the idle rollers 40 and the third roller 41.

According to a still further embodiment (Fig. 4), the magnetic bench is indicated with the reference number 119 and is shaped according to a drum geometry.

In this case the magnetic elements 30 are associated perimetrically to its external circumference and oriented with the thickness in a radial direction.

The magnetic bench 119 has a diameter which, by way of example only, can be between 200 mm and 1000 mm.

The substrate 11 is unwound from the first coil 13, partially winds on the magnetic bench 119 and is rewound on the second coil 14.

The mask 20 is wound on four idle rollers 140, two of which are arranged in an advanced position towards the magnetic bench 119, so as to allow the mask 20 to be attracted by the magnetic action exerted by the latter.

The advancement of the substrate 11 can be imposed by activating, for example, the second coil 14 or, alternatively, by providing for activating the magnetic bench 119 by making it rotate on itself.

The magnetic bench 119, due to the effect of the magnetic attraction action, is able to drag, keeping in close contact with each other, the mask 20 and the substrate 11 to make it advance continuously and thus deposit the thin film 12 on the substrate 11. It is It is clear that modifications and / or additions of parts may be made to the apparatus for depositing thin films on flexible substrates described up to now, without thereby departing from the scope of the present invention. For example, for the deposition of particular patterns on the substrate 11, for example presented empty areas inside the deposited areas, or particular complex drawings it is necessary that the mask 20 is subjected to a well-defined path, and brought into contact several times against the substrate 11 to define a different protective film design according to the position assumed by the mask 20 during its movement.

The mask 20 is divided into two or more parts according to the complexity of the scheme that is to be reported on the substrate, each part is subsequent to the other and each of them is repeated periodically along the entire extension of the mask 20.

Each part of the mask 20 is provided with a determined screen showing the desired pattern to be deposited on the substrate.

In particular (fig. 7), the mask 20 is forced by deviating rollers 50 to follow a determined path. By suitably designing the aforementioned path it is therefore possible to bring into contact at least a first time, a first part of the mask 20 allowing the deposition of a first pattern of thin film, and at least a second time a second part of the mask 20 which shows a second pattern of thin film 12.

The length of the path which detaches the mask 20 from the substrate 11 is equal to or is a multiple of the pitch, or rather the length of each part into which the mask 20 is divided. By way of example only, with reference to figs. 8 - 12, the deposition process of the thin film 12 on the substrate 11 of two different schemes is described.

In particular, the mask 20 comprises along its longitudinal development a first screen 51 and a second screen 52, arranged one in succession to the other and which are repeated periodically.

The first screen 51 and the second screen 52 respectively show a first pattern and a second pattern for depositing on the substrate 11 respectively a first pattern 55 and a second pattern 56 of the thin film 12. The mask 20 is intended to follow a determined path established by the presence of the deflector roller 50. On the side of the mask 20 opposite to that of adherence to the substrate 11, a first deposition device 53 and a second deposition device 54 are arranged, which are arranged respectively on one side and on the other with respect to the deflector roller 50, and are suitable for depositing the thin film 12 respectively in a first part F and a second part S of the printing region P.

In a first instant in time (fig. 8), in the first part F, the substrate 11 adheres to the first screen 51 and the first deposition device 53 deposits on it the thin film 12 according to the first design 55.

In a second instant in time (fig. 9), following the coordinated advancement of the mask 20 and the substrate 11, in the first part F, the second screen 52 is brought directly into contact with the substrate 11 so that the first deposition 53 deposits on the substrate 11 the thin film according to the second drawing 56.

In a third instant in time (fig 10), with a continuation of the advancement of the mask 20 and of the substrate 11, in the first part F, the substrate adheres to the first screen 51 and the thin film with the first is deposited on it. drawing 55.

In a fourth instant in time (fig. 11) / continuing the advancement of the mask 20 and of the substrate 11, in the first part F, the substrate 11 adheres to the second screen 52 so that the thin film is deposited on it with a second drawing 56, while in the second part S, the substrate 11 is arranged with the second pattern 56 deposited in the second instant in time adhering to the first screen 51 so that in correspondence with the aforesaid second pattern 56 the first pattern 55 is also deposited.

In a fifth instant in time (fig. 12), in the second part S, the substrate 11 is arranged with the first pattern 55 which has been deposited in the third instant in time, adhering to the second screen 52 so that in correspondence with the aforementioned first pattern 55 is also deposited the second drawing 56.

By continuing the coordinated advancement of the mask 20 and the substrate 11, it is therefore possible to continuously deposit on the latter two or more desired designs.

Similarly, it is also possible to deposit two or more different materials, for example by providing that the first deposition device 53 and the second deposition device 54 use different deposition sources which act independently of each other. This embodiment is advantageous for example for making thermocouples.

Claims (15)

CLAIMS 1. Apparatus for depositing thin films on a flexible substrate (11) comprising feeding means (13) and extraction means (14) provided for moving the substrate (11) along a given direction of advance (D); a deposition device (17) such as magnetron sputtering, chemical vapor deposition, thermal evaporation, electron beam evaporation, interposed between said feeding (13) and extraction (14) means which is suitable to act in a desired region printing (P) to deposit on at least one surface portion (16) of the substrate (11), which is each time included in said printing region (P), a thin film (12) of material; a mask (20) interposed between said substrate (11) and said deposition device (17) to determine the deposition of the thin film (12) according to a desired scheme; and an advancement device (19; 119) suitable for moving said mask (20) along said advancement direction (D), characterized in that said advancement device comprises holding means (19; 119) suitable for keeping , at least in said printing region (P), said mask (20) and at least said surface portion (16) of the substrate (11) in a direction transverse to said direction of advancement (D) and to integrally constrain said mask (20) and said surface portion (16) in a direction parallel to said advancement direction (D), so as to determine a movement in step with said mask (20) at least with said surface portion (16) of said substrate (11). 2. Apparatus as in claim 1, characterized in that said holding means (19, 119) are of the magnetic type and, with respect to the substrate (11), they are arranged on the opposite side with respect to which said mask (20) is arranged, and that at least a part of said mask (20) is made of ferromagnetic material. 3. Apparatus as in claim 1 or 2, characterized in that said holding means comprise a magnetic bench (19) provided with a plurality of magnetic elements (30) arranged side by side, with respective polarities alternating with each other and defining a contact surface (27) on which said substrate (11) slides. 4. Apparatus as in claim 3 characterized in that said magnetic elements (30) are spaced from each other by spacer elements (31) made of non-ferromagnetic material. 5. Apparatus as in claim 3 or 4 characterized in that said magnetic bench (119) is substantially drum-shaped and on its external surface is suitable for at least partially wrapping said substrate (11) and said mask (20). 6. Apparatus as in claim 5 characterized in that said magnetic bench (119) is suitable for being rotated on itself to determine the advancement of said substrate (11) and the coordinated dragging of said mask (20). 7. Apparatus as in any one of the preceding claims, characterized in that said feeding means comprise a first reel (13) on which said substrate (11) is wound, and that said extraction means comprise a second reel (14) on the which is suitable for wrapping said substrate (11) when said thin film (12) has been deposited on it. 8. Apparatus as in any one of the preceding claims, characterized in that a cleaning device (37), such as an ion gun or an electron gun, is suitable for removing the evaporated material from said deposition device (17) and deposited on said mask (20). 9. Apparatus as in any one of the preceding claims, characterized in that said substrate (11) is selected from a group comprising polymeric materials, paper, synthetic fibers, or the like. 10. Apparatus as in any one of the preceding claims, characterized in that said thin film (12) is selected from a group comprising metallic, ceramic or polymeric materials. 11. Apparatus as in any one of the preceding claims, characterized in that said mask (20) is substantially shaped like a closed ribbon to be carried each time in succession in proximity to said printing region (P). 12. Apparatus as in any one of the preceding claims, characterized in that said mask (20) comprises at least one region which has a plurality of through incisions (22) which define at least one screen (21) of the desired thin film deposition pattern (12). 13. Apparatus as in claim 12, characterized in that said mask (20) comprises at least two successive and possibly adjacent regions having corresponding through incisions (22) to define at least a first screen (51) and a second screen (52) arranged one in succession to the other along the development of said mask (20) and each showing a respective deposition pattern correlated to said passing incisions (21) and suitable for defining on said substrate respectively a first pattern (55) and a second pattern (56 ) of the deposited thin film (12). 14. Apparatus as in claim 13, characterized in that it also comprises deviating means (50) suitable for making said mask (20) follow a determined path to selectively bring said first screen (51) and / or said second screen ( 52) in contact against said substrate (11) respectively and from time to time in a first part (F) and / or in a second part (S) of said printing region (P) to allow the overlapping or possibly staggered deposition or side by side of said first drawing (55) and said second drawing (56) of the thin film (12). 15. Process for depositing at least one thin film (12) on a flexible substrate (11) comprising at least one feeding phase in which said substrate (11) is moved by means of feeding means (13) and extraction means (14) along a direction of advance (D), and a phase of deposition of a thin film (12) in which by means of a deposition device (17), such as magnetron sputtering, chemical vapor deposition, thermal evaporation, electron beam evaporation, which is interposed between the feeding means (13) and the extraction means (14) and which acts in a desired printing region (P), said thin film (12) is deposited in at least a surface portion (16) of the substrate (11), and in which a mask (20) is interposed between the substrate (11) and the deposition device (17) to determine the deposition of the thin film (12) according to a desired scheme, and is moved by a device of long advancement (19; 119) said forward direction (D), characterized in that during the movement of said mask (20), holding means (19; 119) maintain adherent to each other, at least in said printing region (P), said mask (20) and said surface portion (16) of the substrate (11) in a direction transverse to said direction of advancement (D), and rigidly constrain said mask (20) and said surface portion (16) in a direction parallel to said direction of advancement (D), so as to cause a movement of said mask (20) at least with said surface portion (16) of said substrate (11).