WO2006037516A1

WO2006037516A1 - Apparatus for coating a band-shaped substrate

Info

Publication number: WO2006037516A1
Application number: PCT/EP2005/010411
Authority: WO
Inventors: Uwe Braun
Original assignee: Leybold Optics Gmbh
Priority date: 2004-10-01
Filing date: 2005-09-27
Publication date: 2006-04-13
Also published as: DE102004047938B4; DE102004047938A1

Abstract

The invention relates to an apparatus for coating a band-shaped substrate. Said apparatus comprises several evaporator crucibles which are made of a ceramic material, for example, and on the surface of which a metal is melted, for example. The longitudinal axis of said evaporator crucibles extends perpendicular to the direction of advancement of the band-shaped substrate. The substrate is coated evenly when the evaporator crucibles are placed in a specific manner relative to each other and to the substrate.

Description

Device for coating a band-shaped substrate

description

The invention relates to a device according to the preamble of claim 1. Substrates are provided for a variety of reasons with a single or multi-layered coating. One reason for the coating of substrates is to provide the surface of a body, which consists of a relatively soft material, with a hard coating. Examples of these are plastic spectacle lenses provided with an SiO ₂ layer or tools provided with a nitride layer. Other coatings serve to transmit or reflect certain wavelengths of light. Such coatings are used in architectural glass. Coatings can also serve to make plastic containers gas impermeable. Furthermore, plastic films are often provided with a metallic coating in order to be able to use them as a gas-tight packaging material, for example. The coating of the substrates can be done by sputtering, evaporation or other coating methods. The evaporation can be carried out by means of electron beams which strike the material to be evaporated. But it is also possible to evaporate material in a crucible or on a heated surface. The heated surface may be an evaporative boat heated inductively or by current flow. In order to prevent alloy formation between the material to be vaporized and a heated evaporator surface, it is known to place the melting point of the evaporator above the vaporization point of the material to be evaporated (GB 360 826). There is also known an apparatus for continuously steaming endless structures, such as tapes, threads and the like by means of preferably high-boiling metals, the metals being heated in a vessel made of coal, graphite or a semiconductor in a vessel formed as a vessel through which a heating current flows. DE 765 487 C). In another known device of the same type, the evaporator cross-section between different evaporator chambers is weakened (DE 970 246 C). With an embodiment of this device (see Fig. 6) it is achieved that a band, which is guided over the chambers, forms no strips of greater or lesser layer thickness aus¬. For this purpose, two rows of evaporator chambers are seen parallel to each other vorge¬, wherein the chambers, as seen from the side, adjacent to each other or overlapping are arranged. The evaporator chambers are recesses in the evaporator and are not individually energized. Rather, the entire evaporator is connected to voltage. In addition, a device for the continuous vapor deposition of strip-shaped substrates is known in which a plurality of evaporator boats are provided as evaporators, which are arranged perpendicular to the strip running direction and which are moved continuously and supplemented with source material (FR-A 2 052 433). , Furthermore, a device for the continuous vapor deposition of strip-shaped substrates is known, in which a multiplicity of evaporator boats are arranged at the same distance from one another and in the direction of strip travel and which can be heated by direct current passage (JP-A 01 219 157. In: Patents Abstracts of Japan, C-660, 29.11.1989, Vol. 13 / NO.536).

There is also known a device for the continuous coating of strip-shaped substrates with a multiplicity of evaporator boats, wherein the individual evaporator shuttles are arranged offset from each other and all evaporator boats jointly cover a narrow coating zone which extends transversely to the strip running direction (DE 40 27 034 Cl = EP 0 474 964 = US 5,242,500).

Also known is a device for coating a moving and flexible film which comprises a housing and means for evaporating coating material in the housing (GB 2 373 744 A). The evaporation means comprise at least one evaporator boat and a device for feeding two elongate elements of coating material onto the evaporator boat (GB 2 373 744 A). Finally, a vacuum evaporation device for metallizing strip-shaped substrates is also known, which has a plurality of evaporation sources, which are heated and supplied with a metal to be evaporated (WO 03/004 720 A1). This device has means which move the substrate over the evaporator source and means which supply a metal wire to the evaporator sources. Each of the evaporator sources in this case has two recesses which are aligned with each other in the direction in which the substrate moves, and each of the two recesses is supplied with an associated metal wire.

The object of the invention is to reduce the reciprocal interaction of different evaporator sources and thus to improve the uniformity of the band coating. This object is achieved according to the features of patent claim 1. The advantage achieved by the invention is, in particular, that the total Ver¬ steam block can be reduced because more evaporator boats fit on the same strip length. This applies to a large extent when the power is supplied from the underside of the evaporator boats.

An embodiment of the invention is illustrated in the drawings and is in

Described in more detail below. Show it:

Fig. 1 is a schematic diagram of a vacuum evaporation plant;

Fig. 2 is an enlarged detail of Fig. 1; 3 shows an evaporator boat in a first side view;

FIG. 4 shows the evaporator boat of FIG. 3 in a second side view; FIG. FIG. 5 shows an isolated evaporator boat from the plant according to FIG. 2; FIG. FIG. 6 two adjacent evaporator boats in the system according to FIG. 2; FIG. 7 shows an arrangement according to the invention of evaporator boats; 8 shows the simulation of an evaporator boat by means of two point sources;

Fig. 9 is a graph showing the film thickness distribution of a point source on a coated film;

10 is a graphical representation of the layer thickness distribution of a line source.

FIG. 1 shows a schematic side view of a vacuum chamber 1 in which a coating installation 2 is located. This coating installation 2 has an unwinding roll 3, a take-up roll 4 and a coating drum 5. The unwinding and winding rollers 3, 4 are mounted in uprights 6, 7. The corresponding stator of the coating drum 5 is not shown in the drawing. The unwinding roll 3 consists of a wound film 8, which is unwound to the take-up reel 4, wherein it nestles against the underside of the coating drum 5. Below the coating drum 5 can be seen two evaporator boats 9, 10, which are arranged on a table 11. Laterally next to the evaporator boats 9, 10 are wire dispenser 12, 13, the z. B. aluminum wires 14, 15 continuously on the surface of the evaporator boats 9, 10 push. Since the evaporator boats 9, 10 are heated, for example, by a current flowing through them, the ends of the aluminum wires 14, 15 evaporate, and the vaporized metal is deposited on the downward side of the film 8. The evaporator boats 9, 10 may be provided on its upper side with a recess. However, there are also Kermik evaporator boats with a flat surface. It can be seen here that a plurality of evaporator boats 9, 10, 16 to 23 offset from one another and with their longitudinal axis in the direction of movement of the film 8 are arranged. This staggered arrangement of the evaporator boats 9, 10, 16 to 23 is known from DE 40 27 034 C1. It can also be seen that one aluminum wire 14, 15, 24 to 31 is provided per evaporator boat 9, 10, 16 to 23, which is pushed in by the wire dispenser 12, 13 (FIG.

In Fig. 3, the evaporator boat 10 is shown in isolation and in a side view, with the longer side 32 can be seen with the side length 1. The shorter sides 33, 34 are connected to a DC or AC voltage source 35. Due to the DC or AC current flowing through the evaporator boat 10, the vaporizer boat 10 heats up such that the tip 36 of the aluminum wire melts. The molten aluminum spreads over the entire surface 37 of the flat surfaced evaporator boat 10 and vaporizes from that surface 37. The vaporizer lobe or lobes 38 thereby forming spreads outwardly and settles on the foil 8. It would spread with increasing distance to the evaporator boat if it were not hindered by the film 8. This film 8 is located at a distance a from the surface of the evaporator boat 10. The density of the particles forming the evaporator lobe or lobes 38 decreases towards the edge zones.

In Fig. 4, the same evaporator boat 10 as shown in Fig. 3, but with a plan view of the smaller side 34 with the width b. In this case, the film 8 moves into or out of the drawing plane. Here, too, the particle density decreases towards the edge zones. Fig. 5 shows the same evaporator boat 10 again in a view from above, d. H. in a view from the film 8 on the evaporator boat 10, wherein the film movement is indicated by an arrow 39. It can be seen here that the vaporization cloud 38 assumes an approximately elliptical shape in the height of the foil 8. Arranging several evaporator boats in the manner as shown in FIG. 1 of DE 40 27 034, i. parallel to each other and not offset, then overlap the adjacent evaporation clouds or lobes 38, resulting in an uneven coating on the substrate 8.

On the other hand, if the evaporator boats 9, 10 are arranged in the manner described by DE 40 27 034 C1 (FIG. 2), evaporation clouds 38 result, as shown in FIGS shows, ie the evaporation clouds can also have an overlap region 42 here. This cut or overlap region 42 produces stripes on the film 8, because the film 8 is subjected to approximately twice the amount of evaporation material in this region. However, as already mentioned, the particle density in the edge regions is lower than in the central regions, so that a doubling of the amount of evaporator material does not have to occur.

FIG. 7 shows an arrangement according to the invention of four evaporator boats 50 to 53, wherein two of these evaporator boats - the evaporator boats 50 and 51 - lie on a first straight line 54 that runs perpendicular to the running direction of the film 8. At a distance x from the straight line 54 and in the running direction of the film 8, a second straight line 55 runs parallel to the straight line 54, on which the two other evaporator boats 52, 53 are arranged.

The edges 56, 57, 58, 59 of the evaporator lobes 60 to 63 at the level of the film 8 overlap in this case in the static state, i. not moving film 8 not. The evaporator boats 50, 52 on the first straight line 54 have an overlapping area y with the evaporator boats 52, 53 on the second straight line 55 in the horizontal direction. This overlapping region y is selected such that, during dynamic operation, the lower coating of the film 8 produced by the edge regions of the evaporator lobes 60, 61 is compensated by the edge regions of the subsequent evaporator lobes 62, 63 in such a way that the coating of the coating in the central region of the coating Evaporator Keulen 60-69 corresponds.

As a comparison of FIGS. 2 and 7 shows, the distance x can be kept small in transverse evaporator boats. The values for x, y and a are adjusted in such a way that a uniform distribution of the deposited particles arises on the film 8. These values can be determined by experiments. If only two evaporator boats 50, 51 are provided on a straight line 54, the distance l-2y between them is fixed. If the evaporator boats 50, 52 are at different straight lines 54, 55, the distances x and y are determined. In Fig. 8, an evaporator boat 50 is indicated by dashed lines. In order to be able to calculate the layer thickness distribution of the material delivered by this evaporator boat 50 on a film, the evaporator boat 50 will be replaced by two point sources 70, 71, which are arranged symmetrically with respect to an imaginary center line 72. The distances of the point sources 70, 71 to the center line 72 are denoted by c, wherein in a model calculation a practical value for c is a distance of 25 mm. can be set. Taking, for example, a value of 180 mm for the distance a from the point sources 70, 71 to the strip 8, the result is a layer thickness distribution, as shown in FIGS. Physically, this layer thickness distribution is due to the fact that in a high-rate evaporation, the ascending vapor cloud or vapor lobe spread, since many atoms leave the surface of the evaporator 50 and thereby the free path length of the atoms decreases. As a consequence of this, the atoms collide with one another and change their direction of movement into spaces in which a free path length is still present, which results in a broadening of the vapor cloud or steam lobe. This effect occurs not only with an evaporator boat 50, but with all evaporator boats 50-53, so that in the areas where the evaporator lobes overlap between the evaporator boats 50-53, centers of high vapor densities can arise. Starting at a certain evaporation rate of the evaporator boats 50-53, these centers are even larger than the areas directly above the evaporator boat 50-53. On the substrate 8 then arise uneven coatings. Such an overlap of the steam lobes can be prevented if the evaporation rate is kept so low that the vapor density of adjacent steam lobes never becomes so great that zones with high vapor densities are formed between the evaporator boats 50-53 or if the steam lobes are geometrically so decrees that centers of high particle density do not arise even during high-rate evaporation. As evaporator boats, those with a smooth surface can be used which evaporate on its entire surface. However, evaporator boats with hollows can also be used. Ultimately, the decisive factor is not the geometry of the evaporator boats, but the geometry of the evaporator lobes, ie the geometry of the active evaporator zone on the evaporator boat. FIG. 9 shows the layer thickness distribution over a point source at 1 = d = 0. In the illustrated example, 1 = 200 mm, while d = 140 mm. The distribution of the Teilchen¬ density on a substrate at a distance of 180 mm from the evaporator boat 50 is indicated by means concentric rings.

In the outer ring 75, the layer thickness is 75% at 80% of the setpoint. The next inwardly directed ring 76 has a layer thickness which contributes 80% at 85% of the nominal value, while the further inwardly directed ring 77 has a layer thickness of 85% at 90% of the nominal value.

The next ring 78 indicates a layer thickness of 90% at 95% of the nominal value, while the inner circle 79 indicates a layer thickness of 95% at 100%. FIG. 10 shows the layer thickness distribution over a line source at d = 0. The distribution here is different from the point source because the point sources thought on the line influence each other. This results in a maximum at d = 1 = 0. With d growing from 1 = d = 0, the drop is steep because there are no more adjacent shuttles available. At d = 0, the drop with increasing 1 is not so strong, because at 1 = 10 mm further point and evaporator sources are present. The region 80 has a distribution of 50% -55%, while the region 81 has a distribution of 55% -60%. The ranges 82 to 90 have distributions of 60% - 65% and 65% - 70% and 70% - 75% and 75% - 80% and 80% - 85% and 85% - 90%, respectively. 90% - 95% and 95% - 100%, respectively.

Claims

claims

1. Apparatus for coating a belt-shaped substrate which moves perpendicular to the longitudinal direction of at least two evaporator sources, characterized gekennzeich¬ net, that the distance (a) between the band-shaped substrate (8) and the evaporator sources (50, 51 or 50 , 52) and the distance (l-2y or x) between the Verdampfer¬ sources (50, 51 or 50, 52) with each other is selected so that there is a uniform distribution of vaporized material on the substrate (8).

2. Apparatus according to claim 1, characterized in that at least two rows of evaporator sources (50, 51, 52, 53) arranged parallel to one another are provided which have a predeterminable distance x from one another in the running direction of the band-shaped substrate (8).

3. Apparatus according to claim 2, characterized in that the evaporator sources (50, 51, 52, 53) arranged in a row have a predeterminable distance (l-2y) from one another perpendicular to the running direction of the band-shaped substrate (8).

4. Apparatus according to claim 2, characterized in that arranged in a first row evaporator sources (50, 51) with the angeord¬ Neten in a second row evaporation sources (52, 53) perpendicular to the running direction of the band-shaped substrate in a predetermined range ( y) overlap.

5. Device according to claims 1 or 2, characterized in that the evaporator sources (50-53) have substantially rectangular evaporator surfaces, wherein the longitudinal axes of the evaporator sources (50-53) are aligned perpendicular to the running direction of the band-shaped substrate (8) , and that at least two evaporator devices arranged parallel to one another are provided, each with at least two evaporator sources (50, 51, 52, 53), the evaporator sources (52, 53) lying on a first line (54) being opposite to the first on a thereto second parallel line (55) lie¬ lowing evaporator sources (52, 53) perpendicular to the running direction of the band-shaped Sub¬ strates (8) are arranged offset from each other, wherein the offset is selected so that the evaporator sources (52, 53) the second straight line (55) coat those regions of the substrate (8) which are not coated by the evaporator sources (50, 51) on the first straight line (54).

6. Device according to one or more of the preceding claims, characterized gekenn¬ characterized in that the evaporator lobes (56-59) of the evaporator sources (50-53) in the plane of the band-shaped substrate (8) do not overlap.

7. Device according to one or more of the preceding claims, characterized gekenn¬ characterized in that overlap the evaporator lobes (56-59) of the evaporator sources (50-53) in the plane of the band-shaped substrate (8).

8. Device according to one or more of the preceding claims, characterized gekenn¬ characterized in that the evaporator sources (50-53) are evaporator boats.

9. Device according to one or more of the preceding claims, characterized gekenn¬ characterized in that the evaporator sources (50-53) are crucibles.