EP1952441A1

EP1952441A1 - Process for fabricating a flexible electronic device of the screen type, including a plurality of thin-film components

Info

Publication number: EP1952441A1
Application number: EP06831137A
Authority: EP
Inventors: François Templier; Hubert Moriceau; Bruno Mourey; Léa Di Cioccio
Original assignee: Commissariat a lEnergie Atomique CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2005-11-22
Filing date: 2006-11-20
Publication date: 2008-08-06
Also published as: US20080309867A1; FR2893750A1; FR2893750B1; US20090262294A9; JP2009516863A; WO2007060314A1

Abstract

To fabricate a thin-film flexible electronic device of the screen type, comprising a plurality of thin-film components on a glass support: a starting support is prepared, comprising a rigid bulk substrate (32) and a glass sheet (31) fastened to this rigid bulk substrate by reversible direct bonding so as to obtain a removable interface (33); the plurality of thin-film components (41-49) is fabricated on this glass sheet; the glass sheet on which the plurality of thin-film components has been fabricated is separated, from the rigid bulk substrate, by disassembling the interface (33); and, advantageously, this glass sheet and the plurality of thin-film components is transferred to a final support.

Description

A method of manufacturing a flexible screen-type electronic device having a plurality of thin-film components

State of the art and purpose of the invention

The invention relates to an electronic device, active or passive matrix screen type, comprising electronic components in thin layers on a thin support and which has good performance from the point of view flexibility and / or lightness and / or robustness. Active matrix displays are mostly screens

LCD, but more recently appeared so-called electrophoretic screens as well as electroluminescent displays type organic light-emitting diode or OLED (Organic Light Electroluminescent Diodes) or type PLED based on polymers. All these screens use an active matrix based on Thin Film Transistors (TFT) components and other thin-film components (particularly thin film diodes) made from amorphous silicon or polycrystalline silicon on a glass plate. large area and thickness of about 0.7 mm.

For applications on portable equipment (phone, PDA, computers ...) manufacturers are demanding screens increasingly light. Another characteristic sought for screens or electronic devices in thin layers is flexibility, for easier integration into new products, or even to make possible new applications such as an orientation map or a roll-up screen, in particular . A last characteristic sought is robustness. The fragility of the current LCD screens based on thick glass requires the addition of a protective plastic layer on laptops. It would be desirable to get rid of it. Whether we are looking for a greater lightness or a greater flexibility or a better robustness, we try to overcome the thick and rigidity of the support glass plate, in practice 0.7 mm, or even two glass plates as in the case of LCD screens where a color filter is also based on this support. It has been proposed for this purpose to provide these active matrices on a plastic support, which combines lightness and flexibility. Several approaches have been proposed:

- direct manufacturing on plastic: however, this technique has at least two disadvantages: (i) need to reduce the processing temperatures during the various manufacturing steps (due to the poor thermal stability of the plastic) and thus reducing the performance of the TFT, and (ii) delicate handling of the plastic substrates during manufacture (due to their lack of rigidity, ...) resulting in incompatibility with the existing manufacturing lines in the case of send supports;

- by manufacturing on a support and then report (or transfer) to another medium, including in particular the processes known under the names "SUFTLA" and "EPLAR". The "SUFTLA" method of Seiko-Epson (notably described in the document "SUFTLA® (Surface Free Technology by Laser Ablation / Annealing) of S. Utnunomiya et al. -TFT2-1 published in AM-LCD'02 - pp. 37 -40) comprises the following steps: (i) manufacture on a 0.7 mm glass plate of polycrystalline silicon TFT type components and (ii) transfer of the components to an intermediate support using an amorphous silicon sacrificial layer previously deposited between the TFT stack and the glass support and transfer to a final plastic support. Bonding on the intermediate support and then on the plastic support is carried out by a water-soluble resin, for the first, and by an adhesive for the second. This method requires that the first medium (on which the components are manufactured) be transparent to the wavelength of the laser used to reach the sacrificial layer and partially destroy it (in practice by heating the amorphous silicon). In addition, this method is expensive since it implements amorphous silicon, a laser and a double transfer; it may furthermore be difficult to assemble an LCD device with two flexible plastic films. Moreover laser technologies are difficult transferable to large dimensions (which is necessary for screens of significant size) and collages on polymer age badly.

Philips "EPLAR" process (see in particular document 54-

2: Thin Plastic Electrophoretic Displays Fabricated by a Novel Process, SID 05 DIGEST - pp. 1634-1637) does not involve amorphous silicon but a layer of polyimide. More precisely, this process comprises the following steps: (i) depositing on a 0.7 mm thick glass support a polymer layer of a few microns, (ii) manufacturing amorphous silicon TFT components, o (iii) deposition of organic LED layers, o (iii) separation between the support and the polyimide layer: this becomes the TFT component holding layer This process is simpler than the "SUFTLA" process (there is only a single transfer) but remains expensive because the separation step implements a laser separation technique. In addition, the need to fabricate the TFT components on a polymer layer affects compatibility with existing processes and processes and production lines, as well as their performance (in particular: need for a low PECVD deposition temperature, for the insulating layers and semiconductors, hence a lower quality for these layers, difficulty in obtaining a correct flatness resulting in constraints on the final device).

In addition to the aforementioned disadvantages, it should be noted that none of these two processes has so far allowed mass production, mainly because of the difficulty of applying them to large screens. (typically beyond 50 mm diagonal) In addition, these two techniques do not allow the "bottom emission", emission down, due to the residual presence in the final stack of the amorphous silicon layer or the polyimide layer (see the figures in the SUFTLA and EPLAR documents).

Therefore, in general, the subject of the invention is a method of manufacturing an electronic device of the screen type, which can be large dimensions, comprising a plurality of thin-layer electronic components which is light and flexible, while implementing techniques already well validated and low cost, consistent with large dimensions. More particularly, it aims at a process for manufacturing passive or active matrix screens (with thin-film components - of the type

TFT - OLED type, LCD or electrophoretic, in particular), which is light and flexible, simple and of moderate cost.

To this end, the invention proposes a method for manufacturing a thin-film electronic device of the screen type, comprising a plurality of thin-film components on a glass support, comprising steps according to which: a starting support comprising a rigid solid substrate and a glass sheet secured to this rigid solid substrate by reversible direct bonding so as to obtain a removable interface, - the plurality of thin-layer components are manufactured on this glass sheet, the sheet is separated from glass, on which the plurality of thin-layer components have been manufactured, with respect to the rigid solid substrate, by dismounting the interface. Advantageously, this sheet of glass and the plurality of thin-film components are then transferred to a final support.

This invention thus combines the advantages of existing technologies on rigid glass support (the starting support is, at least as regards the sheet, glass), while allowing to obtain a good control of the lightness and flexibility final, by a good control of the thickness of the glass sheet, this thickness being sufficiently small to obtain the desired lightness and flexibility.

In the particular case of the production of active matrix screens, the method of the invention can be described as comprising the following steps: a starting support is prepared comprising a rigid solid substrate and a glass sheet secured to this substrate; solid rigid by a reversible bonding so as to obtain a removable interface, an active matrix of pixels is produced on this glass sheet, a display layer is produced on top of this active matrix, the glass sheet, on which the active matrix and the display layer have been fabricated, is separated with respect to the rigid solid substrate, by dismounting the interface, this glass sheet and the active matrix and the display layer are transferred to a final support, possibly flexible.

This method thus makes it possible to produce screens with flexible active matrices, while using the existing standard manufacturing methods, and to guarantee the performance of these screens. In fact, the advantages of TFT performance on glass technology are preserved and the flexibility provided by a control of the thickness of the glass.

It will be appreciated that the above-mentioned methods of screen manufacture led the skilled person to conclude that the production of flexible screens implied that the support carrying the thin-film electronic components is made of plastic.

It will further be appreciated that the principle of a removable interface was already known, in particular from WO-02/084722. The teachings of this document mainly concern the case of a silicon substrate on a silicon block, with indications for the general case of semiconductor materials such as silicon, germanium, or silicon and germanium compounds, even carbides or nitrides of these elements, or even ferroelectric or piezoelectric or magnetic materials.

However, although this document envisaged applications in the field of screen manufacturing, it had not yet been recognized that its teachings were applicable to a thin and flexible layer of glass (it was well planned that the interface could between layers of silicon oxide, but these were very thin layers carried by substrates of other materials), and that the choice of this material was compatible, for thicknesses sufficiently low, with both the manufacture of components and obtaining a good flexibility.

In other words, the invention notably resulted from the finding that, contrary to what the "SUFTLA" and "EPLAR" methods suggested, the use of a glass support in the final structure of an electronic device flexible screen type was possible, provided to choose for this support a sufficiently thin sheet, which was possible, in particular based on the teachings of WO-02/084722.

In a general manner, according to preferred features of the invention, possibly combined: the starting support is prepared by reversibly bonding the glass sheet to a rigid glass support, which gives the assembly good stability in particular. mechanical and thermal, reversible direct bonding is in practice a molecular bonding, whose performance can be very good, the reversible bonding is preceded by a preparation treatment adapted to make hydrophilic surfaces to be bonded, which contributes to a very good bonding, the surfaces to be bonded have a roughness of less than one nanometer (preferably less than 0.5 nanometer), which contributes to a very good bonding, the starting support is prepared by gluing on the rigid solid support of a glass plate which is then optionally applied a thinning treatment bringing the thickness of the plate to a desired value, allowing and not having to manipulate the sheet separately when it has its final thickness, the glass sheet has a thickness at most equal to 100 microns, preferably at most equal to 50 microns, the plurality of components is manufactured in layer one-step thin film in which an active matrix of pixels is fabricated on the glass thin sheet, and a step of making a display layer over this active matrix of pixels, whereby after separation one obtains an active matrix screen, the active matrix of pixels is produced by forming thin-film components of the TFT type, which is well known to perform well and at low cost, the display layer is manufactured by forming organic electroluminescent components of the OLED type , what is also known to do well, in a high performance and low cost, is deposited by rolling an electrophoretic layer so as to obtain an electrophoretic screen, an LCD screen is made, - separating the glass sheet vis- to the solid rigid support by means of insertion of a blade, which allows a clear separation, without having to heat all as it can be done at room temperature, the glass sheet and the components are carried forward formed thereon on a flexible sheet of plastic material (which is known per se); alternatively, the glass sheet and the components formed thereon are deferred onto a flexible metal sheet.

The invention also relates to a screen-type device obtained by the aforementioned method, namely a flexible thin-film electronic device of the screen type comprising a plurality of thin-layer electronic components located on a glass support whose thickness gives it a significant flexibility, preferably at most equal to 100 microns, or even 50 microns.

It is aimed in particular at an active matrix screen comprising active matrices comprising components in thin layers on a glass sheet whose thickness gives it a significant flexibility, preferably at most equal to 100 microns, or even at most equal to 50 microns .

Thus, the object of the invention is to protect a device of the aforementioned type in which, advantageously, the plurality of components comprises a layer formed of an active matrix of pixels and a display layer covering the active matrix of pixels. . In other words, the flexible electronic device of the invention is advantageously an organic electroluminescent diode screen, or an electrophoretic screen or an LCD screen. Advantageously, the electronic device is such that the electronic components are designed so as to emit light through said glass sheet.

The invention finally proposes a starting support adapted to the manufacture of a flexible thin-film electronic device of the screen type comprising a rigid solid substrate and a glass sheet secured to this rigid solid substrate by a direct reversible bonding so as to get a removable interface.

The rigid substrate is advantageously made of glass, at least on the surface.

Objects, features and advantages of the invention will become apparent from the following description given by way of non-limiting illustrative example in which: FIG. 1 is a block diagram of a thin-film electronic device according to the invention; 2 is a block diagram of a starting support, FIG. 4 is a diagram of another subsequent step of the manufacture of the screen, FIG. 5 is a diagram of a separation step involved in the manufacture of the screen, on the support of FIG. of the screen, Figure 6 is a diagram showing the result of this separation step, and Figure 7 is a diagram showing the final result of the manufacture of the screen. The figures represent, as an example of a thin-film electronic device according to the invention, an active pixel array screen of the OLED type, and a method of manufacturing it. FIG. 1 thus represents a flexible active matrix OLED screen, light and robust.

In this example, the active matrix (i.e. the layer in which the components are made) is made with amorphous silicon; but it will be readily understood that the process of the invention is compatible with temperatures well above those involved in deposit formation

PECVD of amorphous silicon.

More specifically, this screen, designated under the general reference 10, comprises a final support 11, a thin layer 12 attached to this final support, here by means of an intermediate zone 13, two insulating layers 14 and 15 in which are made contacts 16, and an encapsulation layer 17 covering electroluminescent components 18A, 18B and 18C, and a protective layer 19. In practice, there is, between the layers 12 and 14, a metal gate and rear contacts that are not shown. According to an important characteristic of the invention, the layer 12 is a thin layer of glass, that is to say a layer of thickness at most equal to 100 microns, preferably at most equal to 50 microns, so as to that the flexibility of the assembly is defined by the flexibility of the support 11.

An advantage of the device of Figure 1 is that it could be manufactured by implementing thin film deposition techniques on a substrate at least superficially formed of glass, without it was necessary later to separate the components vis-à-vis this glass.

Figures 2 to 7 show how this screen 10 can be manufactured in accordance with the invention. This method of manufacturing a screen can be described briefly by the following steps:

- Manufacture of a starting substrate composed of a stack of a thin sheet of glass and a rigid sheet, advantageously also made of glass, both being temporarily secured by a reversible (molecular) direct bonding so as to form a removable interface; manufacturing, on this substrate, an active matrix of pixels, manufacturing, above the active matrix of pixels, a display layer, separation of the rigid glass support of the screen on a flexible support support if necessary. These various steps are detailed below.

1) Realization of a basic substrate

The base substrate is made from two glass plates 31 and 32 whose shape and size are of little importance, depending on the intended application for the final device. However, the thicknesses of these plates are chosen so as to satisfy several criteria: the overall thickness of these two plates is such that they can be handled together, typically at least on the order of 0.4 to 0.7 mm, for example for a surface of the order of 4 m ² , the bottom plate 31 has a sufficient thickness for this plate, solid, is rigid.

For example, two borosilicate glass plates, 100 or 200 mm in diameter, 0.7 mm thick and 0.2 nm in roughness (measured by AFM on fields of (1 x 1) μm ² ) are used. These plates are intended to be temporarily secured. For this purpose, their roughness is advantageously at most equal to the nanometer, preferably of the order or less than 0.5 nm, which is favorable to a good molecular bonding of the faces facing these plates 31 and 32. If necessary specific layers can be deposited to obtain the required surface roughness. This roughness can be chosen to make possible the subsequent disassembly at the bonding interface.

The bottom plate, whose function is to be rigid and withstand the following component manufacturing processes, can be performed in a wide variety of materials. However, it is advantageous that it be, as indicated above, also in glass, preferably in a glass of the same properties as that of the top plate in order to avoid thermal expansion problems, for example a standard borosilicate type glass of the LCD industry.

In practice, these plates are cleaned to remove particulate contamination, organic or metallic. This cleaning may be chemical type (wet or dry), thermal type, chemical mechanical polishing type or any other nature capable of effectively cleaning the facing surfaces intended to form a removable interface. In the case of wet chemical cleaning, two cleaning compositions may be used: H ₂ SO ₄ , H ₂ O ₂ , H ₂ O, or NH ₄ OH, H ₂ O ₂ , H ₂ O. are then, if necessary, rinsed with water and dried. The person skilled in the art knows how to adapt the cleaning method according to the particular case.

Advantageously, the surfaces to be bonded are at the end of cleaning of hydrophilic nature.

Once the surface treatment has been carried out, the two surfaces of the plates are brought into contact at their prepared faces to carry out the direct bonding.

The two plates thus glued can be annealed, if necessary, to increase the bonding energy. For example, annealing at 420 ^° C. is applied for 30 minutes. One of the two plates, here the top plate, is then thinned to the desired glass thickness for the final device, by a mechanical and / or chemical technique of any known type suitable. This step is optional if the plate considered immediately has the required thickness.

For example, one of the substrates is thinned to 100 μm or alternatively to 75 μm or to 64 μm.

The thickness of the thinned plate, here the upper plate 32, is such that, given the properties of the glass used, this plate has a flexibility compatible with the intended application for the finished product; this thickness is in practice at most equal to 100 microns and preferably at most equal to 50 microns; it is therefore correct to define the thinned upper plate 32 as being a thin sheet of glass. By comparison, the lower plate 31 is a rigid solid plate. The stack presented in FIG. 2 is then obtained, where the surface areas of the two plates affected by gluing, labeled 31A and 32A, together form a bonding interface 33.

Thanks to the provisions implemented for the preparation of surfaces, this interface is removable, that is to say reversible. It is within the abilities of those skilled in the art to draw on the teachings of the aforementioned document WO-02/084722 to control the bonding energy of this interface.

For example, the bonding energy is very low, of the order of 350 mJ / m ² . According to an alternative embodiment, the bonding energy is controlled by acting beforehand on the microroughness of the faces to be assembled. One layer of an oxide or of several oxides (for example SiO ₂ ), whose microroughness is adjusted, is deposited on one of the glass layers before bonding. Those skilled in the art can adjust the microroughness, by modifying the thickness of the deposited layer, and / or by using a specific chemical treatment (for example by etching with hydrofluoric acid HF). If the oxide used is SiO _2, the person skilled in the art will also be able to choose to apply a heat treatment or not to give the SiO ₂ layer the properties of thermal silica (see for example the article The bonding energy Semiconductor Wafer Bonding: Science, Technology and Applications VII, Bengtsson ed, The Electrochemical Society 2003, 49, presented at the Electrochemical Society Conference in Paris, May 2003).

In another form of implementation, the bonding energy is controlled by acting on the micro-roughness of the faces to be assembled, then by performing a cleaning as described above.

The base substrate 31-32 is then used as a standard glass plate for the manufacture of an active matrix with thin-film components, here of TFT type. It is understood that the presence of the removable interface does not substantially modify the mechanical properties of the stack, compared to a monobloc plate of the same thickness. Alternatively, it is of course possible to use for the bottom plate a material different from the glass but whose stack with the upper plate is capable of undergoing the same mechanical and thermal treatments as the stack 31-32: the skilled person can evaluate the characteristics required for such a stack (in particular the nature and the thicknesses of the materials to be retained as well as the associated thermal limitations).

2) Manufacture of the TFT active matrix

FIG. 3 represents a plate of active matrices after the realization of a network of TFT components corresponding to amorphous silicon pixels, in the so-called grid technology below.

Other technologies are of course possible (like the so-called grid technology). Similarly, the components may alternatively be the basis of other materials including polycrystalline silicon.

The conditions of realization can be exactly the same as for a manufacture on conventional glass substrate; in particular, the maximum temperature used can be the same (in general, 300 ^° C., for depositing the layers by the technique known as PECVD). This is made possible by the very nature (of the glass) of the layers of the base substrate and by the ability of the reversible bonding to hold these temperatures. In addition, as indicated, the total thickness of the base substrate is very close to that of a glass plate conventionally used in this type of treatment, 0.7 mm.

The perfect compatibility of treatments with the existing manufacturing lines is a considerable advantage of the invention, particularly with respect to processes requiring the presence of a plastic layer during the manufacture of TFTs (in the "EPLAR" process).

As we know, this network of thin-film components comprises:

A metal grid 41 deposited by any appropriate technique for deposition on the free surface of the glass sheet,

An insulating layer of gate 42, typically made of silicon nitride SiNx, Zones of amorphous silicon 44 deposited on the insulating layer (intrinsic and doped layer stack),

Contacts 43 deposited by any appropriate technique on the silicon layer and forming sources and metal drains,

An insulating passivation layer covering the insulating layer and the contacts, and

Pixel electrodes 46, of the ITO type, for example for an LCD screen, made on this passivation layer, in any appropriate known manner.

For an OLED display, the electrodes will be more like molybdenum or aluminum or any other conductive material allowing the injection of holes or electrons into the OLED.

Transverse strands, such as those identified 47 (these transverse strands are not all shown in the figures, for reasons of readability thereof), are provided in the insulating layers so as to establish the appropriate connections.

The next step is to make a display layer on this active matrix of TFT components.

3) Production of the OLED type screen

FIG. 4 shows the step of adding, on the pixel electrodes, localized layers comprising appropriate organic electroluminescent materials, in practice of Red (48A), Green (48B) and Blue (48C) color, so as to realize an OLED color screen. These localized layers may be, optionally, small molecule organic layers (which results in "OLED" type components) or polymer layers (which results in "PLED" type components). They can be deposited by evaporation, or by ink jet, or by spin coating type. For further details, reference can be made to the article "High efficiency phosphorescent OLEDs and their resolution with PoIy or amorphous TFTS", M. Hack et al., Eurodisplay 2002

Conference, Proc 21-24, Nice Oct. 2002. These localized layers are covered by a conductive layer forming a second electrode or against electrode, more precisely a cathode 49, which is here a continuous plane above the localized layers. This cathode cooperates with the electrodes 46 to form electroluminescent components emitting, depending on the material thus sandwiched, green, red or blue light.

These OLED components are covered with an encapsulation layer 50 which may be SiNx. In the example given, the emission of light is towards the bottom of the screen ("Bottom emission"), which was not possible with the SUFTLA or EPLAR methods. It is nevertheless possible, with an adaptation of the materials, to operate in emission upwards.

The screen formed by the superposition of the TFT components and OLED components is then covered by one or more plastic layers 51 which has a role of protection as well as handle for the subsequent handling of the structure. This layer is for example deposited by rolling (that is to say by unwinding this layer and pressing on the deposition surface).

The manufacture of the screen further comprises a step of connecting the drivers ("drivers") on the screen; this can be done at this stage. In fact, the product obtained at the end of this step comprises the screen to be produced as well as the solid rigid glass layer which facilitated the handling of the assembly during the various manufacturing steps.

It is then necessary to separate this rigid layer vis-à-vis the screen itself.

4) Separation

The separation step consists in separating the screen and the thin layer of thin glass from the rigid layer of thick glass.

The separation is at the location of the direct bonding area. It is advantageously carried out by the insertion of a blade at the locations indicated by arrows in FIG. 5. If the plastic encapsulation layer 50 is strong enough not to break during the separation, it is not useful to use, by gluing from above, a support handle as in the processes explained in the state of the art.

Figure 6 shows the result of this separation, where the original plates were glued. In the embodiment more particularly described, plates are thus separated, one of which is thinned to 75 μm or to 64 μm, without breaking the plate.

It is interesting to note that, because this separation results from the disassembly of the interface initially obtained by gluing, the surfaces exposed by this separation are of flatness and do not require heavy planarization and / or cleaning treatment. . They are therefore, in particular, transparent in the case of downward transmission ("bottom emission").

The screen is dissociated from the glass substrate which has allowed manipulation during the manufacturing steps. It is then possible to implant this screen at its service location.

5) Report

The screen is then transferred to a support 60 of any suitable material, given the application in question, for example a plastic support (see Figure 7); this support is for example polymer such as PET.

Advantageously, this support 60 will be laminated on the screen. It may be noted by comparison of Figures 1 and 7 that the product obtained is in accordance with the desired product. Zone 13, which is the surface area 32A of the plate 32 (see point 1 and FIG. 2), is recognized and which zone of this plate 32 is affected by the reversible bonding.

Fixing the screen, so its thin layer of glass, can be done by gluing.

If one chooses a support that is flexible, because of its nature and / or its thickness (for example with a rather small thickness in the range of 20 to 50 microns) then a flexible screen is obtained. Of course, the support may be more rigid, for example by choosing larger thicknesses between 200 and 700 microns; the screen is not particularly flexible, but it has the advantage of being light and robust compared to an identical screen made on a solid glass support, without separation.

It is thus understood that, the screen being, in the isolated state, flexible and flexible, it is according to its application that the skilled person will choose to retain one and / or the other of these properties.

Thus, the thin product obtained by the process of the invention may alternatively, depending on the requirements, be in particular carried on materials such as a thin metal, for example a stainless steel with a thickness advantageously of between 50.degree. at 200 microns, which allows to maintain the qualities of flexibility, and to improve the solidity and the thermal stability of the whole. It will be appreciated that, if the description has just been given about an OLED or PLED type screen, it is within the abilities of those skilled in the art to adapt the teachings mentioned in point 3 to other applications, such as the production of electrophoretic screens, LCD type screens or PDLC-type screens: for an electrophoretic screen: deposition, for example by rolling of an electrophoretic layer, for an LCD type screen, various technologies are possible (TN, PDLC, STN ...); those skilled in the art will be able to adapt the process accordingly. For TN technology: gluing a thin plate of colored filters (eg glass) and filling with liquid crystal (see Liquid Crystal Displays, Addressing Schemes and Electrooptical Effects for more details) , Ernst Lueder, Wiley Editor, June 2001).

Of course, the removable interface can be made not directly between the exposed faces of two glass plates, but also indirectly, between the bonding layers deposited on these faces to be secured.

It should be noted that the invention provides various advantages, in particular: when the thin sheet of glass is attached to a rigid plate of glass, the support thus produced is completely compatible with known TFT processes, hence a very moderate cost and transistors made at standard temperatures and therefore good qualities, the fact of ensuring the separation at the level of a removable interface allows an excellent control of the thickness of the residual thin layer, in particular to guarantee, if necessary, a determined level of flexibility, which makes it possible to control the performances obtained. , the method of the invention is substantially cheaper than the methods known under the designations of "SUFTLA" and "EPLAR", yet designed for similar applications, due to the fact that it is not necessary to provide equipment laser, a downward emission, or "bottom emission" (see Figures 1 to 7 and the description above), is possible for OLED screens, or for other rans, the method of the invention can be implemented without limitation as regards the dimensions of the device to achieve; it is thus possible to provide devices of several centimeters, or even several tens of centimeters in width and length.

Claims

A method of manufacturing a flexible thin-film electronic device of the screen type, comprising a plurality of thin-film components on a glass support, comprising steps according to which: a starting support is prepared comprising a rigid solid substrate ( 31) and a glass sheet (32) secured to this rigid solid substrate by reversible direct bonding so as to obtain a removable interface (33), the plurality of thin-layer components (41-49) are made on this sheet. of glass, the glass sheet, on which the plurality of thin-layer components have been made, is separated from the solid rigid substrate by dismounting the interface,

2. Method according to claim 1, characterized in that this sheet of glass and the plurality of thin-film components are transferred to a final support (60).

3. Method according to claim 1 or claim 2, characterized in that the starting support is prepared by reversibly bonding the glass sheet (32) to a rigid glass substrate (31).

4. Method according to any one of claims 1 to 3, characterized in that the reversible direct bonding is preceded by a preparation treatment adapted to render hydrophilic surfaces to be bonded.

5. Method according to any one of claims 1 to 4, characterized in that the surfaces to be bonded have a roughness of less than one nanometer.

6. Method according to claim 5, characterized in that the roughness of the surfaces to be bonded is less than 0.5 nanometer.

7. Method according to any one of claims 1 to 6, characterized in that the starting support is prepared by gluing on the rigid solid support of a glass plate to which a subsequent thinning treatment is then applied. the thickness of the plate to a desired value.

8. Method according to any one of claims 1 to 7, characterized in that the thin sheet of glass has a thickness at most equal to 100 microns.

9. The method of claim 8, characterized in that the thin sheet of glass has a thickness at most equal to 50 microns.

10. Method according to any one of claims 1 to 9, characterized in that the plurality of thin-layer components is manufactured in a step according to which an active matrix of pixels (41-47) is produced on the thin sheet of glass. and a step in which a display layer (48A-51) is fabricated over this active matrix of pixels, whereby after separation an active matrix screen is obtained.

11. The method of claim 10, characterized in that the active matrix of pixels is made by forming thin-film components of the TFT type.

12. The method of claim 10 or claim 11, characterized in that manufactures the display layer forming organic electroluminescent components OLED type.

13. Method according to any one of claims 1 to 11, characterized in that is deposited by rolling an electrophoretic layer so as to obtain an electrophoretic screen.

14. Method according to any one of claims 1 to 11, characterized in that an LCD screen is produced.

15. A method according to any one of claims 1 to 14, characterized in that the glass sheet is separated from rigid rigid support means by insertion of a blade.

16. A method according to any one of claims 1 to 15, characterized in that the sheet of glass and the components formed thereon is carried on a flexible sheet of plastic material.

17. A method according to any one of claims 1 to 15, characterized in that the glass sheet and the components formed thereon are carried on a flexible metal sheet.

18. A flexible screen-type electronic device comprising a plurality of thin-layer electronic components (16-18C) located on a support formed of a glass sheet (12) whose thickness, at most equal to 100 microns, confers on it significant flexibility.

19. Electronic device according to claim 18, characterized in that the glass sheet has a thickness at most equal to 50 microns.

20. An electronic device according to any one of claims 18 or 19, characterized in that the plurality of components comprises a layer formed of an active matrix of pixels and a display layer covering the active matrix of pixels.

21. Electronic device according to any one of claims 18 to 20, characterized in that it is an organic electroluminescent diode screen.

22. Device according to any one of claims 18 to 20, characterized in that it is an electrophoretic screen.

23. Device according to any one of claims 18 to 20, characterized in that it is an LCD type screen.

24. Electronic device according to any one of claims 18 to 23, characterized in that said electronic components (16-18C) are designed so as to emit light through said glass sheet.

25. Starting support adapted to the manufacture of a flexible thin-film electronic device of the screen type according to the method of any one of claims 1 to 17 comprising a rigid solid substrate (31) and a glass sheet (32) secured to this rigid solid substrate by reversible direct bonding so as to obtain a removable interface.

26. Support according to claim 25, characterized in that the rigid substrate is glass at least on the surface.