Process for producing organically modified oxide, oxynitride or nitride layers by vacuum deposition

Method for producing at least one organically-modified oxide, oxinitride or nitride layer by vacuum coating on a substrate through plasma-enhanced evaporation of evaporation material comprising nitride-forming evaporation material and one of oxide and suboxide evaporation material, wherein the at least one layer is deposited through plasma-enhanced, reactive high-rate evaporation of the evaporation material with use of gaseous monomers and a reactive gas including at least one of oxygen and nitrogen, and wherein the evaporation material, gaseous monomers, and reactive gas pass through a high-density plasma zone immediately in front of the substrate. A method for producing at least one organically-modified oxide, oxinitride or nitride layer by vacuum coating on a substrate through plasma-enhanced evaporation of one of oxide and suboxide evaporation material, wherein the at least one layer is deposited through plasma-enhanced, reactive high-rate evaporation of the evaporation material with use of gaseous monomers and a reactive gas including at least one of oxygen and nitrogen, and wherein the evaporation material, gaseous monomers, and reactive gas pass through a high-density plasma zone immediately in front of the substrate. Substrates with an organically-modified oxide, oxinitride or nitride layer, as produced by the methods, wherein the at least one layer deposited by plasma-enhanced, high-rate vapor deposition includes more than 50 wt% of inorganic molecules and less than 50 wt% of partially cross-linked organic molecules.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a method for producing organically-modified oxide, 
oxinitride or nitride layers on large areas through vacuum coating. 
Preferred applications of these layers are transparent barrier films for 
packaging materials and transparent corrosion-protective or anti-abrasion 
layers for window faces, mirrors, decorative surfaces, or facade coatings. 
2. Discussion of Background 
It is known to produce layers for these applications by varnishing with 
transparent varnish layers or laminating transparent plastic films. 
Although an adequate barrier or corrosion-protective effect can be 
obtained in many cases, the abrasion resistance is very low, and weather- 
and UV-resistance prove to be insufficient in outdoor applications. 
Much higher abrasion resistances and good barrier or corrosion-protective 
properties can be attained with a much lower material expenditure by the 
application of transparent oxide layers in a vacuum. Coating takes place 
by vapor-deposition, sputtering, or plasma CVD techniques (G. Kienel: 
"Vakuumbeschichtung [Vacuum Coating]",Vol. 5, VDI-Verlag, Duisseldorf, 
1993). However, inorganic oxide layers produced in this way have a much 
lower flexibility compared to organic layers produced by varnishing or 
laminating. This substantially impairs the initially very good properties 
of the vacuum-deposited oxide layers during use and further processing of 
the coated films, sheet metals, or plates. Particularly, subsequent 
stretching or deep-drawing of the coated materials is hardly possible. 
It has already been attempted to combine the high flexibility of organic 
coatings with the high abrasion and weather resistance of the oxide 
layers. Cited as an example are the so-called called "organically-modified 
ceramic layers" ("ORMOCER" layers), which are produced according to the 
Sol-Gel process and are to be applied similarly to varnish layers (R. 
Kasemann, H. Schmidt: New Journal of Chemistry, Vol. 18, 1994, No. 10, 
Page 1117). However, they require a layer thickness similar to those of 
customary varnish layers. Furthermore, although their resistance to 
abrasion and weather is better than that of varnish layers, it is not as 
good as that of thin vacuum-deposited oxide layers. 
Moreover, it is a known method to produce organic layers with an inorganic 
oxide component in a way that the organic layers are deposited by plasma 
polymerization in a vacuum, using organometallic or organosilicon vapors 
as monomers for the plasma polymerization, so that a concurrent oxygen 
admission results in the formation of both metallic oxide and silicon 
oxide molecules that will be incorporated into the growing organopolymeric 
layer (JP 2/99933). Depending on both the monomers and the proportion of 
oxygen used, the oxide component in the organic polymer layer may be 
varied. In this way, layers of greater or lesser hardness can be deposited 
that are characterized by both good abrasion resistance and good barrier 
and corrosion-protective properties. But a disadvantage of this method is 
that true-to-quality layers can be attained only at deposition rates of a 
few nanometers per second. Hence, this technique proves to be unsuitable 
for the economical coating of large areas. 
It is known to apply a layer comprising an inorganic component and an 
organic component to a substrate for improving gas imperviousness, with 
the organic component being non-uniformly distributed in the layer in the 
monomer state (EP 0 470 777 A2). The disadvantage of this method is that 
the layer is too brittle for further processing, and the vapor-deposition 
rates attainable with this method are too low. 
Also known is a method of ion-assisted vacuum coating, in which a plasma is 
used to generate ions. In this method, ions are accelerated toward the 
substrate through the application of alternatingly positive and negative 
voltage pulses, relative to the plasma, between the substrate and a 
coating source (DE 44 12 906 C1). A disadvantage is that the layers 
produced in this manner are too hard for subsequent processing of the 
coated substrate. 
It is known to produce oxide-polymer dispersion layers through simultaneous 
evaporation of polymers and metals with two evaporation sources (U.S. Pat. 
No. 4,048,349). This method is very costly, however, and, in addition, a 
subsequent thermal treatment must be performed for oxidation. 
SUMMARY OF THE INVENTION 
It is an object of the invention to create a method for the production of 
organically-modified oxide, oxinitride or nitride layers by vacuum coating 
that facilitates high deposition rates needed for coating of large areas 
and allows for the deposition of layers that, according to the intended 
application, are characterized either by good barrier properties, 
corrosion-protective properties or anti-abrasion properties, and possess a 
flexibility with which the good properties are sufficiently maintained 
during further processing and use in practice. Extensive homogeneity is 
intended to be attained over large areas. Moreover, it is an aim of the 
invention to produce a substrate with a coating that possesses the 
aforementioned properties. The substrates should be strip-shaped or 
sheet-type substrates of arbitrary material. 
An essential starting point of the method is the plasma-enhanced reactive 
deposition of oxide layers known per se, in which the required high 
deposition rates as well as the required hardness and abrasion resistance 
of the layers can be achieved. Surprisingly, it has been found that the 
additional admission of even small quantities of a suitable monomer into 
the vapor-deposition zone causes an unexpectedly distinct modification of 
the otherwise brittle oxide layers toward a higher flexibility, i.e., an 
increased ductility and bendability. In addition, a higher 
corrosion-protective effect and a better barrier effect against the 
diffusion of gases and vapors are attained. To attain prerequisite for 
attaining these effects it is important that the reactive gas and the 
monomers are introduced near the substrate and at a preferred direction 
toward the substrate site to be coated, and that--together with the 
evaporated, oxide- or nitride-forming elements--they pass through a plasma 
zone of high density immediately before they impact the substrate. The 
admission of reactive gas and monomers with a preferred direction toward 
the substrate minimizes unwanted scatter effects, and therefore ensures 
that the desired components of reactive gas and monomer molecules at the 
substrate surface are already obtained with relatively-low gas flows and 
total pressures. In this way, a higher packing density of the layer 
molecules is attained. The passage through this high-density plasma zone 
prior to impact at the substrate has a decisive influence on the layer 
structure and the resulting layer properties. 
Here the molecules and atoms of the evaporated oxide- or nitride-forming 
element, as well as the molecules of the reactive gas and the monomers, 
are excited, and partly ionized, such that they form a dense 
inorganic-organic molecular network in the growing layer. 
The same effect also occurs if, instead of the oxide- or nitride-forming 
elements such as silicon, aluminum or other reactive metals, their oxides 
or suboxides are evaporated, whereby the quantity of the admitted reactive 
gas can be reduced accordingly. This procedure is of particular advantage 
if the corresponding oxides/nitrides or suboxides/subnitrides are less 
expensive than the oxide- or nitride-forming elements themselves, such as 
silicon dioxide (quartz) compared to silicon. But in most cases, e.g., 
with aluminum, the oxide-forming elements are less expensive and easier to 
evaporate than the corresponding oxides or suboxides. 
For particular applications it may also be of advantage if the layer 
properties vary gradually over the layer thickness. With 
abrasion-resistant layers on plastic film, for instance, it is 
advantageous if the layers on the side facing the substrate are less hard, 
and therefore better matched to the plastic substrate, whereas it is 
desirable for the layer surface facing away from the substrate to have a 
greater hardness. Such a gradient layer structure can also be obtained if 
the substrates to be coated is moved over the vapor-deposition zone at a 
constant speed, and if the admission of either the reactive gas or 
monomers, or the center of the plasma zone, is not located in the center 
of the vapor-deposition zone but, with respect to the direction of 
substrate motion, closer to the beginning or end of the vapor-deposition 
zone. If these sites are arranged near the beginning of the 
vapor-deposition zone, they have a stronger influence on the layer side 
facing the substrate, whereas an arrangement near the end of the zone 
mainly influences the side facing away from the substrate, i.e., the layer 
surface. Generally, a larger reactive gas component yields a higher 
transparency and a greater hardness, but often also a lower flexibility, 
of the layer. On the other hand, a larger monomer component can increase 
the flexibility of the layer, although the hardness is somewhat reduced. 
Finally, an increase in plasma density can permit an enhancement of the 
hardness and adhesion strength of the layers, and also influence the 
transparency of the layers. Hence, the mean value as well as the local 
distribution of reactive gas, monomer and plasma density can be used to 
vary both the mean value and the gradient of the layer properties over the 
layer thickness within wide limits. The most favorable mean values and 
local distributions have to be determined experimentally in accordance 
with the application concerned. 
In accordance with one aspect, the present invention is directed to a 
method for producing at least one organically-modified oxide, oxinitride 
or nitride layer by vacuum coating on a substrate through plasma-enhanced 
evaporation of one of an oxide- and nitride-forming evaporation material, 
wherein the at least one layer is deposited through plasma-enhanced, 
reactive high-rate evaporation of the evaporation material with use of 
gaseous monomers and a reactive gas comprising at least one of oxygen and 
nitrogen, and wherein the evaporation material, gaseous monomers, and 
reactive gas pass through a high-density plasma zone immediately in front 
of the substrate. 
In accordance with another aspect, the present invention is directed to a 
method for producing at least one organically-modified oxide, oxinitride 
or nitride layer by vacuum coating on a substrate through plasma-enhanced 
evaporation of evaporation material comprising nitride-forming evaporation 
material and one of oxide and suboxide evaporation material, wherein the 
at least one layer is deposited through plasma-enhanced, reactive 
high-rate evaporation of the evaporation material with use of gaseous 
monomers and a reactive gas comprising at least one of oxygen and 
nitrogen, and wherein the evaporation material, gaseous monomers, and 
reactive gas pass through a high-density plasma zone immediately in front 
of the substrate. 
In still another aspect, the present invention is directed to a substrate 
with an organically-modified oxide, oxinitride or nitride layer, wherein 
the at least one layer deposited by plasma-enhanced, high-rate vapor 
deposition comprises more than 50 wt% of inorganic molecules and less than 
50 wt% of partially cross-linked organic molecules. 
In another aspect, the evaporation material, gaseous monomers, and reactive 
gas are directed toward the substrate. 
In still another aspect, the at least one layer is deposited at a coating 
rate of at least 10 nm/s. The coating rate may be 20 to 1000 nm/s. 
In yet another aspect, the high-density plasma zone has a density of at 
least 10.sup.9 cm.sup.-3. The high-density plasma zone may have a density 
of 10.sup.10 to 10.sup.12 cm.sup.-3. The high-density plasma zone may have 
a density of 10.sup.9 cm.sup.-3 to 10.sup.10 cm.sup.-3. 
In another aspect, the plasma-enhanced, reactive, high-rate evaporation is 
carried out by one of diffuse arc discharge, pulsed magnetron discharge, 
non-pulsed magnetron discharge, and electron cyclotron resonance (ECR) 
microwave discharge. 
In still another aspect, the evaporation material comprises one of metal 
and metal alloy. The evaporation material may also comprise one of silicon 
and aluminum. 
In another aspect, the gaseous monomers comprise at least one of 
polymerizable hydrocarbon, organometallic compound, organosilicon 
compound, and organofluorine compound. The gaseous monomers may comprise 
hexamethylene disiloxane. 
In another form, the substrate to be coated is uniformly moved over a 
vapor-deposition zone. The reactive gas may enter the vapor-deposition 
zone at one of a beginning, a center, and an end of the vapor-deposition 
zone with respect to the direction of substrate motion. The gaseous 
monomers may enter the vapor-deposition zone at one of a beginning, a 
center, and an end of the vapor-deposition zone with respect to the 
direction of substrate motion. The high-density plasma zone may be 
expanded, with respect to the direction of substrate motion, so that the 
high-density plasma zone is located at one of a beginning, an end, and 
nearly an entirety of the vapor-deposition zone. 
In another aspect, the at least one layer comprises more than 50 wt% of 
inorganic molecules. The at least one layer may comprise more than 80 wt% 
of inorganic molecules. 
In still another aspect, the inorganic molecules comprise one of an oxide, 
oxinitride, and nitride of one of silicon and metal. The metal may be 
aluminum. 
In yet another aspect, the partially cross-linked organic molecules 
comprise at least one of carbon, silicon, metal, and fluorine. 
In another aspect, a concentration of organic molecules in the at least one 
layer decreases from a layer side facing the substrate to a layer side 
facing away from the substrate. 
In yet another aspect, a concentration of at least one of oxygen and 
nitrogen in the at least one layer increases from a layer side facing the 
substrate to a layer side facing away from the substrate.

DETAILED DESCRIPTION 
The substrate 1 to be coated is a plastic film that is provided with a 
highly-reflective metal layer intended for large-area solar reflectors in 
solar power stations, and requires a highly-transparent, 
abrasion-resistant, corrosion-protective and weather-resistant protective 
layer. The substrate 1 to be coated is guided, at a constant speed, from a 
take-off reel 2 via a cooling drum 3 to an take-up reel 4. At a bottom 
side of the cooling drum 3, aluminum is evaporated as an oxide-forming 
element from a series of resistance-heated boat evaporators 5. To 
evaporate other oxide-forming elements such as titanium or zirconium, or 
for evaporating oxides or suboxides such as SiO.sub.2 or SiO, it is 
possible to employ electron-beam evaporators or other high-rate evaporator 
sources instead of the boat evaporators 5. Two magnetrons 7 that are 
pulsed at about 50 kHz in bipolar mode are used to generate the 
high-density plasma zone 6 immediately in front of the substrate. Arranged 
below the plasma zone 6 are two nozzle tubes 8, 9 for the admission of 
oxygen as reactive gas, and two nozzle tubes 10, 11 for the admission of 
the monomer hexamethylene disiloxane (HMDSO). The nozzle tubes 8, 9, 10, 
11 are directed toward the site to be coated on the substrate 1 to ensure 
reactive gas and monomer and the lowest possible pressure in the coating 
chamber. 
After setting the desired aluminum evaporation rate with the aid of the 
boat evaporators 5, and after setting the optimum plasma density in the 
plasma zone 6 as determined by preliminary tests, the oxygen flow through 
the nozzle tubes 8 and 9 is increased by equal amounts until an aluminum 
oxide layer having the required high transparency has been attained. The 
transparency of the deposited layer is measured with the aid of a 
reflection spectrometer 12. After that, the monomer flow through the 
nozzle tubes 10 and 11 is set at the optimum value determined by 
preliminary tests. In general, it proves to be suitable to set a higher 
flow through the nozzle tube 10 than in the nozzle tube 11. Often, the 
monomer admission will result in a reduced transparency of the deposited 
layer that can be largely compensated by a further oxygen admission. In 
the interest of substantial surface hardness of the layer, it is also 
suitable to admit the additional oxygen mainly through the nozzle tube 9.