EP2111652A1

EP2111652A1 - Method for the transfer of structural data, and device therefor

Info

Publication number: EP2111652A1
Application number: EP08707976A
Authority: EP
Inventors: Peter Eckerle; Florian DÖTZ; Udo Lehmann; Hans-Georg Fercher
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-01-19
Filing date: 2008-01-18
Publication date: 2009-10-28
Also published as: US20100201038A1; WO2008087196A1

Abstract

The invention relates to a method for transferring structural data into a functional layer. In a first step of said method, the functional layer is made available on a support layer. In a second step, power is transmitted section by section into the functional layer through the support layer such that the physical and/or chemical properties of the functional layer are modified in the area of said section. The invention further relates to a device for carrying out said method.

Description

Method for transmitting structure information and device therefor

description

The present invention relates to a method for transferring structure information into a functional layer and a device therefor. Such a method is used, for example, in semiconductor technology.

At present, essentially two methods for transferring structure information into a functional layer are known. Thus, for example, WO 03/080285 discloses an apparatus and a method for laser structuring of functional polymers. Functional polymers are understood to mean an organic material which, in a semiconductor component, has a function, such as, for example. For example, conducting or not conducting is accomplished. For structuring pulsed laser light is directed to a photomask, wherein the mask image is reduced with a suitable optics and imaged onto the functional layer to be structured. The pulsed laser light leads to laser ablation, so that a corresponding structure is inscribed in the functional layer.

Apart from this lithography with laser light, it is also known to perform the structuring by continuous printing processes, such as. B. in DE 100 33 1 12 described.

However, the known laser ablation method has the disadvantage that the removed from the functional layers Abtrag is thrown into the laser light and therefore hinders a continuous further removal. Continuous use of the laser light is therefore not possible. In addition, care must be taken that the layer to be removed can absorb the laser light as completely as possible or is almost transparent to the laser, so that an underlying absorption layer can provide the energy transfer.

The choice of materials for the layer to be removed is thus very limited. In particular, when the layer to be removed is reflective, which is often necessary in particular in semiconductor technology, the laser lithography is disturbed, so that the structures do not have the often necessary accuracy. Furthermore, it may be possible that in order to remove reflective layers, the laser power must be increased very much, which increases the cost of the laser ablation process.

In previous laser ablation techniques using a mask, a pulsed laser beam is used. Before the laser beam reaches an area on the sub- Strat is focused, this is passed through an optical imaging unit with mask. In this case, the mask represents the motif to be ablated in an enlarged form. The imaging optics then carry out a projection of this mask image on a reduced scale on the substrate. With such techniques, a small area of, for example, about 20 × 20 mm ² can then be removed in one or more pulses. However, larger structures can not be produced in this way.

Based on this prior art, it is an object of the present invention to provide a method for transferring structural information into a functional layer, which manages with a low laser power, which can perform structuring very quickly and above all very precisely. Furthermore, the method should be able to be operated continuously and have no restriction with regard to the surface of the functional layer to be processed.

According to the invention, this object is achieved in that, in a first step, the functional layer is provided on a carrier layer and in a second step energy is transferred in sections through the carrier layer into the functional layer, thereby resulting in a change in the physical and / or chemical properties of the Functional layer in the range of this section comes.

The method according to the invention is used, for example, for the production of conductive structures, for example printed conductors on printed circuit boards or electrodes. It is also possible with the method according to the invention to structure other functional materials, for example semiconductors or dielectrics. In addition to the manufacture of electronic components, however, it is also possible to use the method for graphic applications in which an image is to be generated.

For the production of electrically conductive structures, electrically conductive materials are preferably used for the functional layer. Such materials are, for example, conductive polymers, preferably polythiophenes or polyanilines. To increase the conductivity, it is possible to add further electrically conductive substances to the conductive polymers. These are, for example, metal powders, carbon nanotubes, zinc oxide, etc. It is also possible to add additives which specifically influence the work function of charge carriers, so that they can easily pass into the energy bands of an adjacent semiconductor. This can be achieved, for example, by coating a conductor track serving as an electrode.

Furthermore, it is also possible to use for the functional layer, for example, an organic semiconductor material or a dielectric. The conductive polymers used for the functional layer are generally available commercially. The carrier layer to which the functional layer is applied is preferably made of a material which is permeable to the laser light used. Suitable carriers are in particular plastic films, for example PET films or polyimide films. For adhesion promotion and smoothing of the surface, the carrier film can be provided with a coating.

Instead of a carrier film, it is alternatively also possible to use a rigid carrier. The rigid support may be, for example, a rigid plate made of a transparent plastic or of glass.

Before the structure can be prepared by energy input from the functional layer, it is necessary to apply the functional layer on the carrier. The application of the functional layer to the support can be carried out using any coating method known to those skilled in the art. Usually, the material for the functional layer is applied in solution to the carrier. Any application known to a person skilled in the art is suitable for application. Such coating methods are, for example, common printing methods. Alternatively, however, it is also possible to apply the material for the functional layer by sublimation. If the stability of the functional layer is insufficient after application, the functional layer can be cured to avoid blurring of the structures. The curing of the functional layer is preferably carried out thermally or by UV radiation, wherein the preferred method depends on the sensitivity of the materials of the functional layer and the speed requirements in which the functional layer is to cure. It should be noted that curing by UV radiation is faster, but can lead to the destruction of sensitive materials.

The application of the functional layer and, if appropriate, drying and curing of the functional layer is preferably carried out in a process passage with the subsequent structuring.

The thickness of the functional layer is dependent on the nature of the material of the functional layer. When conductive polymers are used, thicknesses of 200 nm to 1000 nm are preferred. For use as semiconductors, thicknesses of about 100 to 300 nm and for dielectrics at 100 nm to 10,000 nm are preferred.

Because the energy is transmitted through the carrier layer, the removal of the functional layer takes place on the opposite side, so that there is no impairment of the beam path. It is therefore possible to operate the laser beam continuously. A change in the physical and / or chemical properties of the functional layer is understood to mean not only the partial removal of the functional layer. It is rather z. B. also possible, with the help of the by the carrier The energy transmitted through it will induce a phase transition or a chemical reaction in the functional layer. All that is essential is that the treatment layer, which is generally smooth and homogeneous before treatment, is structured after the treatment in some form, ie that some sections in chemical or physical form differ from other sections.

In a particularly preferred embodiment it is provided that the energy is transmitted through the carrier layer in an absorption layer, which is located between the carrier layer and functional layer, and is transferred from the absorption layer into the functional layer. In this case, the laser only has to be adapted to the absorption layer. The transmission and absorption properties of the functional layer are of subordinate importance, since the laser beam is already completely absorbed in the absorption layer and from there transfers the energy into the functional layer (essentially via heat conduction).

In general, the absorption layer contains an absorbent for the laser employed and a binder by which a uniform film is formed on the support surface. In addition, additives for adhesion promotion to the support and / or with respect to the functional layer, viscosity adjustment, as crosslinker for the binder or also for coloring may be contained in the absorption layer. It is also possible for additives to be present in the absorption layer which influence the dielectric or conductive properties of the absorption layer. The absorbent used must be matched to the laser used. This applies in particular to the use of organic or inorganic compounds which absorb specifically in the wavelength range of the laser radiation. Another suitable absorbent is carbon black, which absorbs nonspecifically over a wide range of wavelengths. The binder for the absorption layer must be selected so that the absorbent used remains bound in the binder. Since the absorption layer is also usually removed during structuring with the laser, it is not necessary for the binder to be stable with respect to the laser radiation. However, neighboring areas must not be damaged.

A further alternative embodiment provides that the energy transfer is selected such that the absorption layer and thus also the functional layer are completely removed in sections.

It is possible to fill the resulting recess with another material. Advantageously, the energy transfer takes place with the aid of a laser beam, which preferably has a wavelength between 150 and 3000 nm. In principle, any laser source is suitable for the method according to the invention. This also does not play Whether a pulsed or continuously operated laser is used. In order to produce a precise patterning to the functional layer, it is preferred that the power of the laser is selected to be less than 20 μJ per laser spot. This makes it possible to use an inexpensive system, which allows faster work than at a higher power. Due to the low power per laser point, an operating frequency up to the 100 MHz range is possible.

Alternatively, the energy transfer can also take place with the aid of an electron beam.

The structural information which is transferred into a functional layer is, in a particularly preferred application of the method according to the invention, an electronic circuit diagram or part of an electronic circuit diagram.

Of course, it is also possible that a plurality of separate functional layers are provided. In this case, each functional layer can also be assigned its own absorption layer, the absorption layers then advantageously having mutually different absorption spectra and the energy transfer taking place with the aid of light beams of different wavelengths. Thus, with the aid of a light beam having a fixed wavelength, a structure can be introduced into the first functional layer, while in another simultaneous or separate operation with a light beam of a wavelength deviating therefrom, a structure is introduced into the second functional layer.

In a further preferred embodiment it is provided that the energy transfer takes place without a mask, namely using a continuous laser beam, which is imaged by means of suitable optics on the desired surface.

The whole process according to the invention can be implemented continuously as a roll-to-roll process. In this case, a transparent to the laser beam band is used as a substrate, which is coated in a continuous process, first with the absorption layer and then with the functional layer. The band can be structured during its movement through the coating mechanism following the coating by means of a laser beam. On the one hand, it is possible to coat the strip in a first working step and first to wind it up on a roll. The coated, wound tape may optionally be stored temporarily. For structuring, the coated strip is fed to a functional unit in which structuring takes place in a second working step. However, it is preferable first to apply the functional layer to the band and then to directly form the structure by ablation. In this case, that does not apply Winding up after the application of the functional layer, since the job and the structuring are carried out in one work step.

According to the invention, the laser ablation takes place in a continuous step. For this purpose, the carrier layer formed as a transparent band with an absorption layer applied thereto, which has been coated with the functional layer, is penetrated by a laser beam which is focused on the absorption layer. The absorption layer is preferably optimized for the laser used. After passing through the transparent carrier tape, the energy of the laser beam is converted directly into heat in the absorption layer optimized for the laser without the laser beam having to penetrate the functional layer beforehand.

This type of laser structuring has the advantage that the functional layer does not have to be adapted to the laser beam used. Almost any materials can be used for the functional layer. Basically, the laser does not have to be adapted to the functional layer, so that less expensive laser units can be used.

In addition, the exposure is from behind, i. through the carrier layer, to increase the process speed, since the laser ablation is transported away from the laser and thus leads to no optical interference, as is the case in the known lithographic processes. In principle, it is advantageous for certain applications if a suction device or a blowing device is provided with the aid of which the laser removal can be removed. Of course, the laser ablation can also be removed in other ways. For example, it is possible to use a solvent for cleaning.

It should be mentioned at this point that according to the invention can be dispensed with the absorption layer, in which case the functional layer itself must be absorbent.

It has been found that the laser ablation can be made more effective in some applications, if the functional layer and / or the absorption layer contains solvents. The proportion of the solvent in the functional layer and / or the absorption layer is preferably in the range between 1 and 70% by weight. The sudden evaporation of the solvent by the energy transfer supports laser ablation.

The solvent can be supplied, for example, before the energy transfer of the relevant layer. In cases in which the functional layer and, if appropriate, the absorption layer are applied to the carrier layer with the aid of solvent. were brought, the energy transfer step can also be done before the solvent has evaporated completely out of the composite layer.

Further advantages, features and possible applications will become apparent from the following description of a preferred embodiment and the accompanying figures.

Show it:

FIG. 1 shows the schematic layer structure,

Figure 2 is a schematic representation of the method according to the invention and

Figure 3 is a schematic representation of a preferred embodiment of the method according to the invention.

FIG. 1 shows a schematic representation of the layer structure before structuring.

An absorption layer 2 is applied to a carrier layer 1, which may for example be formed as a transparent strip, which can be unwound from a roll. The absorption layer 2 contains at least one substance which absorbs incident laser light and converts it into heat. On the absorption layer 2, a functional layer 3 is applied. The functional layer 3 preferably contains electrically conductive materials, such as conductive polymers. According to the invention, the absorption layer 2 and the functional layer 3 are applied to the carrier layer 1 in a first step. The application of the absorption layer and the carrier layer takes place, for example, by a printing process known to those skilled in the art.

FIG. 2 shows a schematic representation of the ablation process.

A laser beam 5, which is controlled for example via an ROS unit (raster output scanner) (not shown here), is focused onto the absorption layer 2 by the carrier layer 1. The absorption layer 2 absorbs the laser light of the laser beam 5 and converts its energy into heat. As a result, the absorption layer 2 is heated so that it evaporates. As a result, the applied on the absorption layer 2 functional layer 3 is removed. The removed as laser ablation 4 of the support layer 1 parts of the absorption layer 2 and the functional layer 3 move away from the carrier layer 1. Since the laser beam 5 is focused on the absorption layer 2 by the carrier layer 1, the laser ablation 4, which is located in the Substantially moved in the same direction, in which also the laser beam 5 shows, the optical path of the laser beam 5 is not.

FIG. 3 schematically shows a preferred embodiment of the method according to the invention.

The inventive method is preferably carried out in a device that combines several process steps. For this purpose, the carrier layer 1, which is designed as a transparent band, is moved continuously by a roller 10 through the device. In the embodiment shown here, the carrier layer 1 formed as a transparent band is guided through a first coating unit which comprises a pressure roller 6 and a pressure roller 13. On the pressure roller 6, the material for the absorption layer is applied. This is transferred to the carrier layer 1 as soon as the carrier layer 1 is passed between the pressure roller 6 and the pressure roller 13. With the help of the pinch roller 13, the carrier layer 1 is pressed against the pressure roller 6.

In a first drying unit 1 1, which adjoins the first coating unit, the absorption layer 2 is dried.

In a second coating unit comprising a second pressure roller 7 and a second pressure roller 14, the functional layer 3 is applied to the absorption layer 2. The mode of operation of the second coating unit corresponds to the mode of operation of the first coating unit. Instead of the pressure roller 6, 7, against which the carrier layer 1 or absorption layer 2 to be coated is pressed with the aid of the pressure roller 13, 14, any other, known to the expert printing device for applying the absorption layer 2 and the functional layer 3 may be provided. For example, the application of the absorption layer 2 and the functional layer 3 can also take place by means of screen printing, indirect or direct gravure printing, flexographic printing, letterpress printing, pad printing, ink jet printing or any other printing process known to those skilled in the art.

The second coating unit may be followed by another drying unit, which is not shown here. In this second drying unit, the functional layer is dried.

The carrier layer 1 coated with the absorption layer 2 and the functional layer 3 is now fed to the actual laser ablation. The laser ablation comprises a laser source, not shown here, from which the laser beam 5 is emitted. The laser source further comprises a laser switching and deflection unit (ROS). Farther a suction device 12 is provided, with which the laser ablation 4 can be sucked off.

With the aid of the laser beam 5, the regions of the functional layer which are to be recessed are selectively removed together with the absorption layer 2, as shown in FIG. 2, from the carrier layer 1. The thus structured layer structure, comprising the carrier layer 1, the absorption layer 2 and the functional layer 3, can then be re-printed or provided with further layers, for example with the aid of further coating units, each comprising a pressure roller 8, 9 with corresponding pressure roller 15, 16 , In each case, a further drying unit 11 can be connected to the coating units. Instead of the coating units, each comprising a pressure roller 8, 9 and a pressure roller 15, 16, it is also possible to use any other, known in the art coating device. Alternatively, it is also possible to dispense with the further coating units comprising the pressure rollers 8, 9 and pressure rollers 15, 16. This is the case in particular if no further layers are to be applied after the ablation step.

After the structure has been worked out of the functional layer 3 with the aid of the laser beam 5 and the layer composite is optionally provided with further layers in the further coating units, it is wound up on a roll 17. In the form of this role, the layer composite can be transported to other processing stations.

LIST OF REFERENCES

1 carrier layer

2 absorption layer

3 functional layer

4 laser ablation

5 laser beam

6, 7, 8, 9 pressure roller

10 roll

1 1 drying unit

12 suction device

13, 14, 15, 16 pinch roller

17 roll

Claims

claims

1. A method for transferring structure information into a functional layer, wherein in a first step the functional layer is provided on a carrier layer and in a second step energy is transferred in sections through the carrier layer into the functional layer, thereby resulting in a change of the physical and / or or chemical properties of the functional layer in the range of this section comes.

2. The method according to claim 1, characterized in that the energy is transmitted through the carrier layer in an absorption layer, which is located between the carrier layer and functional layer, and is transferred from the absorption layer in the functional layer.

3. The method according to claim 2, characterized in that the energy transfer is selected so that the absorption layer is partially completely removed.

4. The method according to any one of claims 1 to 3, characterized in that the energy transfer takes place by means of a laser beam, which preferably has a wavelength between 150 and 3000 nm.

5. The method according to any one of claims 1 to 4, characterized in that the energy transfer takes place with the aid of an electron beam.

6. The method according to any one of claims 1 to 5, characterized in that the structure information is an electronic circuit diagram or parts thereof.

7. The method according to any one of claims 1 to 6, characterized in that at least two separate functional layers are provided.

8. The method according to any one of claims 1 to 7, characterized in that at least two absorption layers are provided, wherein the two absorption layers preferably have mutually different absorption spectra and the energy transfer takes place with the aid of light beams of different wavelengths.

9. The method according to any one of claims 1 to 8, characterized in that the functional layer is cleaned after the energy transfer step.

10. The method according to claim 9, characterized in that the ablation removed by the functional layer is sucked off or blown away or the functional layer is cleaned with the aid of a solvent.

1 1. A method according to any one of claims 2 to 10, characterized in that the absorption layer and / or the functional layer is supplied before the energy transfer step solvent.

12. Device for transferring structure information into a functional layer (3) with a supply device for supplying a carrier layer (1) provided with the functional layer (3) and an energy-emitting device, which is designed such that energy is introduced in sections into the functional layer (3 ), characterized in that the energy-emitting device is arranged in such a way that the energy can be released through the carrier layer (1) into the functional layer (3).

13. The apparatus according to claim 12, characterized in that as energy-emitting device, a laser (5) is provided.

H. Apparatus according to claim 12 or 13, characterized in that a plurality of lasers whose laser wavelengths are different, are provided.

15. Device according to one of claims 12 to 14, characterized in that a suction and / or blow-off device (12) for sucking off and / or for blowing off of the functional layer (3) and / or absorption layer (2) ablated material is provided ,

16. Device according to one of claims 12 to 15, characterized in that the supply device for supplying a with a functional layer (3) provided carrier layer (1) a feed for the carrier layer (1) and a device for applying the functional layer (3) and optionally the absorption layer (2).

17. The apparatus according to claim 16, characterized in that the means for applying the functional layer (3) and optionally the absorption layer (2) comprises a pressure roller (6, 7) and a pressure roller (13, 14).