FR2936965A1 - Via realization method for fabrication of e.g. optical device, involves permitting localized projection of immiscible liquid material with forming material used for forming organic thin layer - Google Patents

Abstract

The method involves permitting localized projection of an immiscible liquid material (2) with a forming material for forming an organic thin layer (1). The thin layer is provided on a support (3). A via (4) is opened on the support, where the immiscible liquid material comprises metallic nanoparticles or Baytron(RTM: Registered polymeric material) type conductive polymers. The thin layer forming material is liquid or gel and selected from a group consisting of monomer material, oligomer material, polymer material, liquid molecule, polymer gel and nanoparticle loaded solution. Independent claims are also included for the following: (1) an electrical device comprising a via covered with an electrically conductive material (2) an optical device comprising a via covered with material having optical properties.

Description

TRAINING VIA THROUGH THIN LAYERS BY LOCALIZED EJECTION OF IMMISCIBLE LIQUID

FIELD OF THE INVENTION The field of the invention relates to the structuring of thin organic layers, liquid or gelled, in their entire thickness, and more specifically the production of via or interconnection holes passing through these thin layers.

Thus, the present invention relies on the use of printing techniques for locally ejecting an immiscible material with the material constituting the thin layer, capable of digging a hole therein.

There are many applications, especially in the manufacture of electronic and / or optical components.

PRIOR STATE OF THE TECHNIQUE

To produce devices in organic electronics (transistors, diodes, capacitors, thermistors, ...), it is imperative that the various layers that make up the components are localized and structured to avoid, in particular, short circuit or leakage of electric currents. . In addition, to be integrated in a circuit, the different basic devices must be able to communicate with each other, through interconnections. Furthermore, to make optical components by printing, it is necessary to be able to juxtapose, on a substrate, materials having different real and imaginary optical indices. It is therefore necessary to properly locate the materials relative to each other without them mixing. In the field of organic electronics, the realization of geometric patterns and via in a layer can be done using conventional methods of microelectronics, that is to say, photolithography steps. However, these methods remain expensive and their compatibility with commonly used organic materials remains limited. In addition, during the step of derisking, it often happens that the different layers of organic materials are peeled from each other.

A particular technique is described in the document Ma, ntysalo et al. (Electronic Components and Technology Conference, 89-94, 2001). This method is based on the use of photocurable materials. The layers are deposited one after the other, and thus the via is formed by localized deposition of the materials. This process is limited to photocurable materials. In addition, the resolution of the patterns is limited by the size of the drops ejected, and is at best 80 micrometers.

The publication of Kawase et al. (Adv., Mater 13 (21), 1601-05, 2001) describes an alternative method that uses inkjet printing technology. The organic material is deposited by liquid and then preferably annealed. The via is created by controlled ejection of solvent drops. This solvent is chosen for its effectiveness in dissolving the organic material locally. By ejecting the drops of solvent exactly in the same place, a via is digging little by little and simultaneously, a bead is created around the via. This bead is detrimental to the quality of the walk. In addition, this method is limited to materials that are free of crosslinking.

A last method identified in the field of organic electronics is that described in the publication of Sirringhaus et al. (Science 290 (5499), 2123-26, 2000). The substrate is covered with hydrophilic or hydrophobic zones, obtained from thin layers. Depending on the nature of the ink, it is preferentially located on one of the two zones. This method therefore uses a deposition of a thin layer of hydrophilic or hydrophobic material on the substrate, followed by patterning performed by photolithography techniques. It is therefore not very compatible with printing techniques.

In the field of optical components, document US 2004/0008319 exposed the possibility of modulating optical indices by juxtaposing drops of photopolymerizable materials having different optical indices. However, the difficulty of controlling the interactions between the drops and the substrate makes the process hazardous, the drops having a tendency to coalesce with each other.

WO 2006/013250 explains how to obtain optical components by filling micrometer sized cells with liquids with given optical properties. However, the precise filling of these cells and their sealing remain delicate because of the pollution generated during the manufacture of such components. SUMMARY OF THE INVENTION

There is therefore a clear need to develop easy and inexpensive methods for creating, in a controlled manner, via via thin films of a very diverse nature.

In the remainder of the description, via is meant a hole or passage entirely traversing the thin layer in which it is made. In practice, this via makes it possible to reach the support on which the thin layer is deposited and thus to establish a possible interconnection between the support and a material situated above the thin layer or deposited in the via.

Thus, the invention relates to a method for producing via via an organic thin layer comprising a localized projection step of a non-immiscible liquid material with the material constituting the thin layer.

The crossing of the thin layer can be done through a single projection. However, it may be necessary to repeat the projection step at the same location more than once, and more precisely the number of times required to cross the thin layer. The process according to the invention is based on the physical principle of phase separation, also known as demixing. The mixing incompatibility between the ejected liquid material, hereinafter called phase II, and the constituent material of the thin layer, hereinafter called phase I, results in their immiscibility. Due to the physical forces associated with phase separation, this second phase (II) repels the constituent material of phase I. Thus, the thin layer formed by the material of phase I is deformed. It should be noted that the material of phase II is not a solvent of phase I.5. The present invention focuses on the formation of via in thin films. This implies that the projection must be repeated at the same place to induce the digging of the thin layer to cross it. In other words and in a preferred embodiment according to which the thin layer rests on a support advantageously a substrate, the via formed at the end of the process according to the invention makes it possible to reach this support or substrate.

As already said, the thin film is organic in nature. In practice, this material constituting phase I is in liquid or advantageously gelled form. It is also advantageously produced by liquid printing, in particular by ink jet, microdispense, screen printing, flexography or heliography on a support, for example a solid substrate or a support itself covered with at least one other layer of ink. 'interest..

Thus, the materials commonly used for the production of thin films by printing and targeted by the present invention are advantageously polymers, molecules, or dispersions of nanoparticles, more precisely chosen from the following group: monomers or molecules in solution; liquid molecules at ambient temperature and pressure; - polymers in solution; polymer gels advantageously obtained by photopolymerization or thermopolymerization; oligomers in solution; - liquid monomers; - charged solutions in nanoparticles, in particular metallic.

A thin film targeted by the invention advantageously has a thickness of between 50 nanometers and 200 micrometers in its liquid or gelled state, ie at the time of projection. This implies that the via formed after the process have a depth within this range.

Furthermore and advantageously, the material constituting the thin layer has a viscosity of less than 300 cps. The viscosity values mentioned in the present application are determined using the Brookfield technique well known to those skilled in the art (ambient T, P = 1 atm). Regarding the material used to make the via in the thin layer, it has the essential property of being immiscible with the material of the thin layer. In other words, it has a mixing incompatibility with the constituent material of the thin layer. In addition, the localized projection of the material constituting the phase II is advantageously made using a microdispense head or an inkjet printing head. Preferably, this is a liquid ejected from the head in the form of drops. Thus, the projection of the immiscible material on the thin layer, preferably in the form of drops, causes the formation of cells which are hollow to form a via via.

Moreover, the viscosity of the materials in the presence, the degree of gelation of the constituent polymers of phase I, as well as the volume of phase II are as many as 20 parameters which make it possible to control the resolution of the patterns obtained.

By moving the layer and / or the projection device, it is possible to create via at different locations of the thin layer. The structure (especially the diameter) and the frequency of the via created in the thin layer can therefore be chosen and controlled. Thus, particularly as a function of the drop ejection step, it is possible to juxtapose the deformation zones and to produce various topologies. In a particular case, it is possible to juxtapose the projections so as to dig a trench in the thin layer. This case finds particular application in the formation of the source and drain of a transistor, the trench then corresponding to the transistor channel. If the immiscible liquid of phase II has a high value of vapor pressure (greater than or equal to 1 mmHg at Patm and Tambiante), it evaporates rapidly and then leaves a vacuum. It follows the creation of a via which has a topology characterized by the absence of redeposition on the upper part of the via. The upper part5 of the via has a slight shoulder. This can allow the passage of march of the metal layer which will eventually be deposited thereafter in and around the via.

Alternatively, if the ejected liquid contains metal nanoparticles (for example the Cabot ink ink AG-IJ-100-S1) or conducting polymers of the Baytron type (Pedot / Pss, HC Stark), it appears in the via, a deposit driver. This then promotes the resumption of contact between the upper electrode and lower electrode.

If the constituent liquid of phase II, with a low vapor pressure value (less than or equal to 1 mm Hg at atmospheric pressure and ambient temperature), does not evaporate and if the ejection operation is regularly carried out repeated on the support, the via are then filled by the constituent material of phase II. In this embodiment and in order to avoid the coalescence of the ejected drops, the constituent material of phase I is advantageously in the form of a gel.

As appropriate, it is possible to eject at different locations immiscible liquid materials of different nature, in particular having different real and imaginary optical indices.

In a particular embodiment, the phase II liquid is ejected onto a thin layer containing nanoparticle dispersions or onto a solution of Baytron type conductive polymers (PEDOT / PSS, HC Stark). In addition, the ejection is performed by juxtaposing series of drops. It is then possible to create the source and drain of a transistor. Drops which can be around 5 micrometers delimit the size of the channel of the transistor, which is a resolution much higher than that commonly obtained when printing conductive tracks by ink jet (about 50 micrometers). This particular method is also useful for structuring thin layers containing the materials necessary for forming the gate dielectric or the semiconductor.

More generally, the method which is the subject of the present invention finds applications in the realization of: electrical devices comprising a thin layer traversed by means covered by or filled with an electrically conductive material; optical devices comprising a thin layer traversed by via filled with a material having optical properties of interest.

EXEMPLARY EMBODIMENT OF THE INVENTION The manner in which the invention may be implemented and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments, given by way of non-limiting indication, in support of the appended figures. FIG. 1 schematically represents a sectional view of a thin layer 10 consisting of a dielectric and resting on a substrate, crossed by a via obtained by means of the method according to the invention. 2 schematically represents a sectional view of a thin layer consisting of a dielectric and resting on a substrate, through which a via according to the invention filled with a conductive deposit promoting the resumption of contact between the upper electrode 15; and the lower electrode. 3 schematically represents a sectional view of a thin layer consisting of a first material and resting on a substrate, through which a via according to the invention filled with the second material used for the localized projection. FIG. 4 schematizes the creation of the source and the drain of a transistor: the channel is formed by the projection of juxtaposed drops of an immiscible material (A) which is then evaporated (B).

Example 1: A commercial solution of CYTOP apolar low-K fluoropolymer is flexographically deposited on a flexible polyethylene naphthalate substrate (Teonex Q65 Dupont Teijin film, 3). The thickness of the layer is 20 microns before annealing and the viscosity of the materials that compose it is 100 cps. The sample is fed to the DMP 2818 dimatix inkjet machine equipped with a 10 picoliter printhead.

The drops of 1-butanol (1 to 50 drops) are ejected locally, by localization of via. After evaporation of the ejected and annealed liquid from the layer (1), we observe the formation of via (4), whose size, in this case the diameter, varies from 4 to 300 micrometers (Fig. 1). This is all the more important as the number of drops deposited per location is high.

Example 2

A commercial solution of CYTOP apolar low-K fluoropolymer is flexographically deposited on a flexible polyethylene naphthalate substrate (Teonex Q65 Dupont Teijin film, 3). The thickness of the layer is 20 microns before annealing and the viscosity of the materials that compose it is 100 cps. The sample is fed to the Asymtek machine equipped with a microdispense head.

A drop of water is ejected by each location of via. After evaporation of the drops of water and annealing of the layer (1), we observe the formation of via (4) whose size or diameter is 300 micrometers (Fig. 1).

Example 3: A commercial solution of CYTOP apolar low-K fluoropolymer is flexographically deposited on a flexible polyethylene naphthalate substrate (Teonex Q65 Dupont Teijin film, 3). The thickness of the layer is 15 microns and the viscosity of the materials that compose it is 100 cps. Without being annealed, the sample is fed to the dimatix inkjet machine DMP 2818 equipped with a 10 picoliter printhead. 10 to 100 drops of Cabot AG-II-G-100-Si ink, loaded with silver nanoparticles, are ejected locally for each via location. The Cabot AGIl-G-100-51 ink drops demix with the constituent materials of the Cytop fluoropolymer thin film.

After annealing the layer (1), we observe the formation of via (4) whose size or diameter varies from 10 to 300 micrometers. This is all the more important as the number of drops deposited per location is high. The inside of the via contains a metal deposit (2) which facilitates the resumption of contact between the upper electrodes (6) and the lower electrodes (5) (Fig. 2). Example 4

A commercial solution of Nissan Sunever polyimide SE-5291 is deposited by flexography on a flexible substrate of polyethylene naphthalate type (Teonex Q65 Dupont Teijin film, 3). Its thickness is 25 micrometers and the viscosity of the materials that compose it is 75 cps. Without being annealed, the sample is fed to the Dimatix DMP 2818 inkjet machine equipped with a 10 picoliter printhead.

1 to 20 drops of a mass mixture of 99.5% water and 0.5% Surfinol 480 (Air Product) are ejected locally. The drops of water demix with the polyimide layer. After annealing the layer (1), the formation of via (4) in the layer is observed (Fig. 1). The size or diameter of these via varies from 5 to 300 micrometers. This is all the more important as the number of drops deposited per location is high.

Example 5

A commercial solution of Nissan Sunever polyimide SE-5291 is deposited by flexography on a flexible substrate of polyethylene naphthalate type (Teonex Q65 Dupont Teijin film, 3). Its thickness is 25 micrometers and the viscosity of the materials that compose it is 75 cps. The sample is immediately fed, without intermediate annealing step, to the Altadrop inkjet machine (Altatech). The printer is equipped with a 60-micron microfab head.

1 to 20 drops of a fluoropentane derivative CT-Solv.100 (Asahi Glass) are ejected locally. The drops of fluoropentane demix with the monomer mixture. After evaporation of the fluoropentane and after annealing the layer at 120 ° C. for 60 minutes, the formation of via (4) in the layer (1) (Fig. 1) is observed. The size or diameter of these via varies from 10 to 100 micrometers. This is all the more important as the number of drops deposited per location is high. 930 Example 6:

The thin layer is made from the following mixture: ethyl hexyl acrylate 30% + nonyl acrylate 69% (monomer mixture); - 1% irgacure 651 (Ciba) (radical initiator).

The solution of the mixture is flexoprinted on polyethylene naphthalate PEN (Teonex Q65 Dupont Teijin film, 3). The thickness of the layer thus obtained is 15 microns and the viscosity of the materials that compose it is 25 cps. The sample is immediately fed, without intermediate annealing step, to the Altadrop inkjet machine (Altatech). The printer is equipped with a microfab head of 30 micrometers.

Drops of a mixture by weight of 99.5% water and 0.5% Surfinol 480 (Air Product) are ejected locally. The drops of water demix with the monomer mixture. After UV irradiation at 365 nanometers for 200 seconds at an energy of 7 mW / cm2 and after evaporation of the water by annealing, the formation of via (4) in the layer (1) (Fig. 1) is observed. Their size or diameter varies from 30 to 200 micrometers. This is all the more important as the number of drops deposited per location is high.

Example 7

The thin layer is made from the following mixture: ethyl hexyl acrylate 30% + nonyl acrylate 69% (monomer mixture); - 1% Irgacure 651 (Ciba) (radical initiator).

The solution of this monomer mixture is flexoprinted on a polyethylene naphthalate PEN substrate (Teonex Dupont Teijin film, 3). The layer is gelled by ultraviolet light irradiation at 365 nanometers for 5 seconds at an energy of 2 mW / cm 2. The thickness of the layer thus obtained is 12 micrometers. The substrate is immediately fed to the Altadrop Inkjet Printing Machine (Altatech). The printer is equipped with a 30 micrometer Microfab head. From 1 to 20 drops of a fluoropentane derivative CT-Solv.100 (Asahi Glass) are ejected locally. The drops of fluoropentane demix with the constituent materials of the layer. After evaporation of the fluorinated solvent CT-Solv.100 and after UV irradiation at 365 nanometers for 200 seconds at an energy of 7 mW / cm 2, the formation of via (4) in the layer (1) is observed (Fig. 1). Their size or diameter varies from 50 to 100 micrometers. This is all the more important as the number of drops deposited per location is high.

EXAMPLE 8 An experiment was carried out on a thin layer of 10 microns thick consisting of: 30% ethylhexyl acrylate + 65% nonylacrylate + 4% ethyleneglycol dimethacrylate (monomer mixture); - 1% Irgacure 651 (Ciba) (radical initiator).

The solution of this monomer mixture is flexoprinted on a PEN substrate (Teonex Dupont Teijin film, 3), previously coated with a polymer alignment layer such as the product Nissan Sunever. The layer is gelled by ultraviolet light irradiation at 365 nanometers for 5 seconds at an energy of 2 mW / cm 2. The sample is fed to the Dimatix DMP 2818 inkjet printer without an intermediate annealing step. The printer is equipped with a 10 picoliter head.

20 drops of liquid crystal TL205 (Merck) are ejected for the creation of each via.

After photopolymerization of the layer (1), a structure is observed which has a juxtaposition of via (4) filled with liquid crystal (2) (FIG 3). The diameter of the via is 100 micrometers. This component may have applications in the optical field and in that of the display.

Example 9

An experiment was performed on an AG-IJ-G-100-S1 silver ink thin film (CABOT) containing silver nanoparticles. The layer is ink-jet printed on a polyethylene naphthalate PEN substrate (Teonex Q65 Dupont Teijin film, 3). The printing equipment used is a dimatix inkjet machine DMP 2818, equipped with a 10 picoliter printhead. The thickness of the annealed front layer is 5 micrometers and the viscosity of the materials that compose it is 3 cps. The sample is immediately taken to the ALTADROP inkjet printing machine, equipped with a 30 micrometer Microfab head.

Drops of a derivative of fluoropentane CT-Solv.100 (Asahi Glass) are ejected so that they juxtapose when they are deposited on the substrate. The drops of fluoropentane demix with the constituent materials of silver ink AG-IJ-G-100-SI (1). After evaporation of the fluoropentane (2), and after annealing the layer at 120 ° C for 60 minutes, the formation of two parallel conductive lines is observed. They correspond to the source (7) and the drain (8) of the transistor (Figure 4). The space between the source and the drain corresponding to the channel (9) varies between 5 and 50 micrometers. The inter-electrode distance is all the more important as the number of drops deposited per location is high.

Claims (13)

REVENDICATIONS1. A method of producing via (4) passing through an organic thin layer (1) comprising a localized projection step of at least one liquid material (2) 5 immiscible with the material constituting the thin layer (1). 2. A method of producing through via an organic thin layer according to claim 1, characterized in that the projection is repeated at the same location the number of times necessary for the crossing of the thin layer (1). 3. A method for producing via via an organic thin film according to claim 1 or 2, characterized in that the thin layer (1) rests on a support (3) and in that the via (4) opens on said support ( 3). 15 4. A method for producing via via an organic thin film according to one of the preceding claims, characterized in that the material constituting the thin layer is in liquid or gelled form, and is advantageously in the following form: monomers, oligomers or solution molecules, solution polymers, liquid monomers or molecules, polymer gel, nanoparticle loaded solutions. 5. A method of producing through via an organic thin layer according to claim 4, characterized in that the thin layer (1) has a thickness of between 50 nanometers and 200 micrometers in its liquid state or gelled. 6. A method of making via via an organic thin film according to one of the preceding claims, characterized in that the material constituting the thin layer has a viscosity of less than 300 cps. 30 7. A method for producing via via an organic thin film according to one of the preceding claims, characterized in that the immiscible liquid material (2) is sprayed locally using a microdispense head or a head inkjet printing. 10 25 8. A method of producing via via an organic thin film according to one of the preceding claims, characterized in that the immiscible liquid material (2) undergoes evaporation after the projection step. 9. A method of producing through via an organic thin film according to claim 8, characterized in that, after evaporation of the immiscible liquid material (2), the via is covered with a metal layer. 10. A method for producing via via an organic thin film according to one of the preceding claims, characterized in that the immiscible liquid material (2) comprises metal nanoparticles or conductive polymers, which form a conductive deposit after evaporation of the liquid . 11. A method of producing via via an organic thin film according to one of the preceding claims, characterized in that after the step of spraying, the immiscible liquid material (2) and / or the material constituting the thin layer (1) are subjected to a polymerization step. 12. An electrical device comprising a thin layer (1) traversed by via (4) made using the method according to one of claims 1 to 11, said via (4) being covered or filled with a conductive material. electric. 13. Optical device comprising a thin layer (1) traversed by via (4) made using the method according to one of claims 1 to 12, said via (4) being filled with a material having properties optics of interest.