WO2003074193A2

WO2003074193A2 - Method and device for the production of a surface coating by means of nir and uv aftertreatment

Info

Publication number: WO2003074193A2
Application number: PCT/EP2002/002248
Authority: WO
Inventors: Kai K. O. BÄR; Rainer Gaus; Rolf Wirth; Martin Schweizer
Original assignee: Advanced Photonics Technologies Ag
Priority date: 2002-03-01
Filing date: 2002-03-01
Publication date: 2003-09-12
Also published as: AU2002308228A8; AU2002308228A1; WO2003074193A3

Abstract

Disclosed is a method for producing a surface coating (101), which includes activation of an initial substance, particularly activation of monomers or a short-chain compound for forming polymers or a cross linkage, on the surface of a carrier (103) by shortwave electromagnetic radiation at invisible wavelengths. The initial substance is subjected to longer wave radiation by a second source of radiation (115) with high power density, particularly radiation in the near infrared range, essentially simultaneous to or immediately preceding radiation with the short electromagnetic waves of a first source of radiation (123).

Description

Method and device for producing a surface coating

description

The invention relates to a method and a device for producing a surface coating according to the preamble of claim 1 and claim 10.

Surface coating systems which contain a component which can be activated by high-energy electromagnetic radiation for curing or crosslinking have been known for a long time and are in practical use. These include, in particular, printing inks that can be activated or crosslinked or UV-curable furniture varnishes using ultraviolet light (UV). The use of photoresists that can be hardened with UV radiation or X-rays for the structure generation in highly integrated semiconductor circuits has also gained considerable technical importance.

Printing ink systems of this type are normally relatively low-viscosity solvent systems in order to enable easy application to the substrate and to largely avoid surface defects during application. From an environmental point of view, efforts are increasingly being made to use water-based systems, i. H. with the largest possible proportion of water in the

Solvent system. In these systems, the solvent must be present before or almost simultaneously with the activation of the hardenable or crosslinkable component - in modern systems a relatively large proportion of water - be removed from the applied layer.

In the case of UV-activatable or UV-curable systems, it is known that, by using a broadband radiation source which, in addition to UV radiation, also emits into the infrared range, the applied layer can be heated to evaporate the solvent. However, because of their broadband nature, such lamps are only of limited suitability for highly specific systems in which the provision of specific spectral components is important. In addition, they are not very energy efficient.

For the use of UV or X-ray-curable structuring systems in the semiconductor industry, additional heating of the carrier, that is to say especially of a semiconductor wafer, via a heating plate is known. However, problems can arise here in that the doping profile generated in the preceding steps with high precision changes undesirably in the semiconductor wafer or other undesirable thermal effects occur in the wafer.

The invention is therefore based on the object of providing an improved method and a corresponding device of the generic type which can in particular be optimally adapted to special requirements of modern coating systems and work with improved energy economy.

This task is done with regard to their. Method aspect solved by a method with the features of claim 1 and in terms of their device aspect by a device with the features of claim 10.

The invention includes the basic idea that radiation activation or cross-linking by short-wave coating systems to be processed on the one hand and electromagnetic evaporation of solvent components of the applied layer on the other hand with two separate irradiation devices.

As a result, a radiation source with an optimal emission spectrum can be selected for each of the existing subtasks and the generation and action of parts of the spectrum of the electromagnetic radiation that are not required for either process can be avoided. This in turn largely prevents possible harmful effects of such radiation components on the overall process. In addition, the energy efficiency of the process is fundamentally increased.

The invention further includes the idea of removing radiation in the near infrared range, in particular in the wavelength range between 0.8 μm and 1.5 μm, for removing the solvent component - in particular water or a mixture of water and organic solvents in aqueous systems use. This component of the spectrum of electromagnetic waves, also referred to as "NIR radiation", is particularly well absorbed by such systems, and their use therefore results in a particularly high energy efficiency of the overall process.

In a first preferred method, UV radiation is used as short-wave electromagnetic radiation in a manner known per se, the spectrum of which is suitably matched to the activation or crosslinking characteristics of the coating system. Depending on the system to be processed, mercury vapor lamps or lasers operating in the UV range, for example excimer lasers, can be used here. In another important embodiment, X-ray or gamma emitters are used as the source of short-wave electromagnetic radiation, for example for resist hardening in semiconductor technology.

In order to achieve the shortest possible process times, which are particularly advantageous with thermally sensitive substrates, the longer-wave radiation on the surface of the applied layer system preferably has a power density of more than 300 kW / m ² , especially more than 500 kW / m ² and also for special applications over 700 kW / m ² . This enables drying times of the coating of less than 10 s, especially 5 s or less and in selected systems even 3 s or less. With such short exposure times of the longer-wave electromagnetic radiation, there is no significant heat conduction into the depth of the carrier, so that the carrier remains relatively cold.

The coating material used in the method according to the invention is in particular one of the under

From an environmental point of view, preferred aqueous systems, that is to say an aqueous solution or dispersion, the solvent components - in particular water components - of which are essentially completely evaporated in a short time by the NIR radiation. Through a suitable choice of the power density and duration of treatment, a certain residual moisture of the layer for the treatment step with the short-wave radiation can be set if necessary. In economically particularly important applications, the systems mentioned are liquid lacquer or a printing ink with a UV-curable or crosslinking binder component. The above-mentioned application for the production of highly integrated circuits is a structuring resist that can be UV, X-ray or γ activated. The mentioned special advantages of the proposed method and the device for T-sensitive materials come, for example, in the production of printed products - in particular on paper, but also on textile substrates -, in the production of refined paper products by lamination or lacquer coating or in wood or plastic lacquering , in particular in furniture production or the manufacture of household items or vehicle interiors or the like, has an advantageous effect.

With the proposed method, known layer systems can be treated in layer thicknesses that are optimal for the respective application. This is in particular layer thicknesses of between 1 micron and 500 mm, with larger values more (eg. B. ^'furniture) for the lacquer coating of durable goods are used, while values in the lower region, in particular between 2 .mu.m and 50 .mu.m, for printing inks and temporary cover layers, for example in semiconductor technology, apply.

The above-mentioned special method aspects are also reflected in special configurations of the proposed device, so that it will not be discussed in detail again. A number of special device features should be pointed out below:

In an advantageous embodiment, the irradiation device for generating NIR radiation comprises at least one, but preferably a plurality of halogen lamps, which are operated in particular at a lamp temperature of over 2500 K, preferably over 2900 K. Elongated tubular halogen lamps of a type known per se are particularly suitable for the majority of the practically relevant applications, because with them a relatively wide - and by arranging several lamps in parallel next to each other also slightly longer - irradiation. can be generated with a sufficiently homogeneous power density distribution. For special applications, for example for carriers of small dimensions and / or with an essentially circular shape - the use of a halogen lamp designed approximately as a radio emitter can also be useful.

The NIR radiation source - in particular the halogen lamp or halogen lamps - is preferably assigned reflectors for concentrating or focusing the radiation on the support of the coating system to be treated. Depending on the desired shape of the radiation zone, the reflector or the reflectors have a partially elliptical, partially parabolic or essentially W-shaped cross section. Inexpensive manufacture of the proposed device in this embodiment is possible with reflectors which have a plurality of appropriately designed reflection surfaces for one halogen lamp each, in which several halogen lamps are therefore inserted.

In order to enable reliable operation of the device over a long period of use and to avoid undesired shifts in the radiation spectrum towards longer wavelengths, the reflectors are preferably actively cooled. This is done in a particularly simple manner by means of integrated fluid flow channels and a connected water cooling.

A further increase in the energy economy of the method is possible by using side or counter reflectors, the latter being particularly advantageous in the case of transparent or semi-transparent coating systems and supports. The arrangement of the radiation source with the assigned reflectors (also referred to as main reflectors) and the side or counter reflectors is preferably such that an essentially closed radiation space is formed in which almost no radiation losses occur. If the type of radiator used for the short-wave or high-energy radiation makes this appear advantageous, means for optical beam shaping are also assigned to these radiators. Conventional UV lamps are in particular also reflectors. With a suitable design of the overall system, the reflectors assigned to the NIR emitter or the NIR emitters can also serve as reflectors for the UV radiation for certain applications. In contrast, if a laser is used as the UV radiation source, a beam expansion (using a system known per se) can be useful.

When irradiating smaller objects, the system can be designed in a particularly simple manner in such a way that the carrier with the coating system as a whole lies in a radiation zone generated by the radiator (s) for the long-wave radiation and is briefly irradiated in a kind of "flash" process , This would be practical, for example, in semiconductor technology.

For larger and in particular for quasi-endless carriers, in particular furniture panels or paper webs in a printing process, the carrier of the coating system, on the other hand, passes through a fixed irradiation device which creates an irradiation zone with a predetermined contour, or the irradiation device is moved over the carrier. It goes without saying that in this embodiment of the method and the device, the carrier or the irradiation device has a drive, which can be adjusted in particular to an exact feed rate.

The proposed device preferably comprises at least one measuring sensor for detecting a physical size of the coating which is relevant for the process of removing the solvent from the coating, in particular a based smoothly working temperature sensor (especially a pyrometer element) and / or a moisture sensor and / or an optical measuring device for detecting the reflectivity or absorption capacity of the coating.

Using the measurement signals from this sensor or these sensors, the longer-wave radiation source can be controlled "manually" by means of a suitable radiation control device. In particular, the operating voltage of a halogen lamp as an NIR emitter and / or the distance between the emitter and the coating system can be controlled.

In a further preferred embodiment, the irradiation controller input is connected to the sensor or sensors and -the ^'includes a control device for operation of the device in a closed control loop.

Advantages and advantages of the invention result from the subclaims and the following description of two preferred exemplary embodiments with reference to the figures. Of these show:

Fig. 1 is a schematic longitudinal sectional view of a system for processing a with a UV-curing

Ink system printed paper web and

2 shows a sectional illustration of a device for resist treatment on semiconductor wafers in the context of an IC production process.

1 shows a printing ink drying and crosslinking path 100 for drying a fast-running paper web 103 provided with prints 101 made from a UV-curable printing ink. The prints 101 lie on passing the printing ink drying and crosslinking section 100 as a liquid, in particular aqueous, layer with a UV-crosslinkable binder component. As shown in the figure, they can be localized, but it can also be a layer of paint or lacquer covering the entire surface of paper web 103. The paper web 103 is transported by transport rollers under the printing ink drying and crosslinking line 100 through transport rollers 105. The drying and crosslinking section 100 comprises two basic components, namely an NIR drying module 107 with a drying control unit 109 and a UV crosslinking module 111.

The NIR drying module 107 consists of a one-piece solid Al reflector 113 with four internally polished reflector sections 113a with an approximately W-shaped cross section and four halogen filament lamps 115, each located in the center of a reflector section 113a, and is via cooling water pipes 117 connected to an external cooling device. A pyrometer element 119, which is embedded in the reflector block 113 and is connected to a measurement signal input of the drying control unit 109, detects the surface temperature of the paper web 103 or the imprints 101 in the drying method defined by the reflector 113 in cooperation with the halogen lamps 115. irradiation zone.

The operating voltage of the halogen lamps 115 is controlled as a function of the measurement signals of the pyrometer element 119 in such a way that the surface temperature on the paper web 103 is kept constant with high accuracy.

The UV crosslinking module 111 as the second component of the drying and crosslinking section 100 comprises a second Al reflector 121 with two reflector sections 121a with parabolic schematic cross section, in each of which a mercury vapor lamp 123 is seated as a UV radiation source.

In the direction of conveyance of the paper web indicated by the arrow, the freshly applied prints 101 first pass through the

Drying zone under the NIR drying module 107, where essentially all of the solvent components are evaporated, and then the crosslinking irradiation zone under the UV crosslinking module 111, where the remaining binder component is crosslinked.

2 shows a resist drying and curing device 200 for use in an ICE manufacturing process.

A plurality of semiconductor wafers 203 are deposited on a plate 201 and are covered with a liquid resist layer (not shown) with a UV-curable photoresist, which is applied by spinning in a constant, small thickness.

Guide rails 205 are attached above the plate 201, on which an irradiation arrangement 209 is displaceably suspended by an electric motor 207 at an adjustable speed. The irradiation arrangement 209 comprises an excimer laser 211 as a UV radiation source with a beam expansion device 213 for producing a substantially rectangular UV radiation zone covering the width of the plate 201.

The irradiation arrangement 209 further comprises a solid aluminum reflector 215 designed as an extruded profile, which is connected via cooling water lines 217 to a water cooling system (not shown) and has an approximately W-shaped cross section, and an elongated halogen filament lamp arranged in the center of the "W" 219th The halogen lamp 219 is assigned an irradiation control unit 221, which is connected via a control input to a pyrometer element 223 used for contactless temperature measurement. The halogen lamp 219, in cooperation with the Al reflector 215, generates an NIR irradiation zone on the plate 201 carrying the semiconductor wafers 203, which in the direction of movement of the irradiation arrangement 209 - symbolized by the arrow below the upper guide rail 205 - during the drying and curing step UV radiation zone leads ahead. In the NIR radiation zone, essentially all of the solvent components of the photoresist are evaporated by the NIR radiation of the halogen lamp irradiated with a high power density before the dried resist is cured in the UV radiation zone. The NIR radiation is controlled in the manner described above for the first exemplary embodiment.

The implementation of the invention is not limited to the examples and highlighted aspects described above, but is also possible in a variety of modifications that are within the scope of professional action.

LIST OF REFERENCE NUMBERS

100 ink drying and crosslinking line

101 Imprint 103 Paper web 105 Transport roller 107 NIR drying module

109 drying control unit

111 UV crosslinking module

113, 121; 215 AI reflector

113a, 121a reflector section 115; 219 halogen filament lamp 117; 217 cooling water pipe

119; 223 pyrometer element

123 mercury vapor lamp

200 resist drying and curing device 201 plate

203 semiconductor wafers

205 guide rail

207 electric motor

209 irradiation arrangement 211 excimer laser

213 beam expander

221 radiation control unit

Claims

claims

1. Process for producing a surface coating

(101) including an activation process of a starting material caused by short-wave electromagnetic radiation with wavelengths below the visible range, in particular the activation of monomers or a short-chain compound for the formation of polymers or for crosslinking, on the surface of a support (103; 203) , characterized in that the starting material substantially simultaneously and / or immediately before irradiation with the short-wave electromagnetic radiation from a first radiation source (123; 211) a longer-wave radiation from a second radiation source (115; 219) with high power density, in particular radiation in Area of the near infrared, is exposed.

2. The method according to claim 1, d a d u r c h g e k e n n z e i c h n e t that UV radiation is used as short-wave electromagnetic radiation.

3. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that X-ray or γ radiation is used as short-wave electromagnetic radiation.

4. The method according to any one of the preceding claims, characterized in that the longer-wave radiation has substantial portions in the wavelength range between 0.8 microns and 1.5 microns.

5. The method according to any one of the preceding claims, characterized in that the longer-wave radiation acts on the starting material with a power density of over 300 kW / m ² , in particular over 500 kW / m ² and even more specifically over 700 kW / m ² .

6. The method according to any one of the preceding claims, that the starting material is in solution, in particular an aqueous solution or dispersion, the solvent or water portion of which is essentially completely evaporated by the longer-wave radiation on the surface of the support.

7. The method according to claim β, d a d u r c h g e k e n n z e i c h n e t that a water-based liquid lacquer or a printing ink or a photoresist with a UV-curing or cross-linking component is used as the starting material.

8. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the starting material on the surface of the carrier as a layer with a thickness in the range between 1 microns and 500 microns, in particular between 2 microns and 50 microns, is present.

9. The method according to any one of the preceding claims, characterized in that a temperature-sensitive organic or biological material, in particular a plastic, wood material or paper, or semiconductor material, 'is used as the carrier (103; 203).

10. The method according to any one of the preceding claims, that the irradiation of the carrier or a surface area thereof with the short-wave and longer-wave

I radiation is carried out for a period of less than 10 s, in particular less than 6 s and more particularly less than 3 s.

11. The device (100; 200) for producing a surface coating including one caused by short-wave e- lectromagnetic radiation having wavelengths below the visible area activation process of a starting material, in particular the activation of mono e- ren or a short-chain compound ^'in the formation of Polymers or for crosslinking, on the surface of a support, characterized by

- a first radiation source (123; 211) for generating the short-wave radiation, - a second radiation source (115; 219) for generating longer-wave electromagnetic radiation with • high power density, in particular in the near infrared range,

- a holding and / or transport means (105; 201, 205, 207) for holding the carrier second in a generated by the first radiation source the first radiation zone and a ^'second radiation zone generated by the second radiation source or for transporting the carrier through the first and Radiation zone and - an irradiation control device (109; 221) for controlling the first and second radiation sources and / or the holding or transport device in such a way that the longer-wave radiation immediately before and / or essentially simultaneously with the short-wave radiation is applied to the surface of the carrier provided with the starting material.

12. The device according to claim 11,

I d a d u r c h g e k e n c e i c h n e t that the second radiation source (115; 219) has at least one, in particular elongated tubular, halogen filament lamp, which is operated at a lamp temperature of more than 2500 K, in particular more than 2900 K.

13. The apparatus of claim 12, so that the second radiation source has a plurality of elongated tubular halogen filament lamps (115), in particular arranged essentially parallel to one another.

14. Device according to one of claims 11 to 13, that the second radiation source is a mercury vapor lamp or a UV laser, in particular an excimer laser.

15. Device according to one of claims 11 to 14, characterized in that the first and / or second radiation source, in particular both radiation sources, the radiator spatially closely adjacent means for beam shaping (111, 113; 213, 215), in particular at least one reflector with part -Eliptical, partially parabolic or essentially W-shaped cross-section for forming the first or second radiation zone with or has a geometrically defined contour.

16. Device according to one of claims 11 to 15, so that the second radiation source has at least one spatially spaced additional reflector for concentrating the second radiation source.

Long-wave radiation diffusely scattered or reflected by the carrier or passed through the carrier is assigned to the second radiation zone.

17. Device according to one of claims 11 to 16, so that the first and / or second radiation zone essentially comprise the entire surface of the carrier (203) provided with the starting material.

18. Device according to one of claims 11 to 17, so that the first and / or second radiation zone successively sweep essentially the entire surface of the carrier (103) provided with the starting material.

19. Device according to one of claims 11 to 18, characterized by a, in particular non-contact, sensor (119; 223) for detecting a process-relevant physical size of the starting material on the surface of the carrier, in particular its temperature, moisture content and / or optical Characteristics.

20. The apparatus according to claim 19, characterized in that the one or more sensors (119; 223) with a data input or data inputs of the radiation control device (109; 221), in particular for forming a closed control circuit, is or are, wherein the first and / or second radiation source (115, 123; 211, 219) and / or holding or transport device (105; 201, 205, 207) is controlled as a function of the output signal of the sensor or sensors.

21. Device according to one of claims 11 to 20, a gas stream generating device for generating a gas stream directed in particular approximately parallel to the surface of the carrier for cooling the surface or removing evaporated solvent or dispersing agent.