Method and apparatus for thin film deposition on a substrate

The invention relates to a method for coating an elongated carrier with a thin film by vapor plasma coating in a vacuum container, in particular for the production of electrophotographic recording media, decorative objects and the like., In the vacuum container in an electric field, a plasma vapor containing the coating material generates and the carrier in the container is exposed to this plasma vapor. The vapor plasma coating is also referred to as glow discharge coating or sputtering. Electrophotographic recording media are to be understood as meaning electrophotographic films and plates, electrophotographic copying paper and optionally electrophotographic memories.

A development of the invention relates to a device for carrying out the method, with io a feed device for the carrier to be coated, a receiving device for receiving the coated carrier and a vacuum container in which an electric field glowing discharge conditions for a vapor plasma coating can be produced.

According to the known methods in known devices, it is basically possible either to accommodate the elongated carrier from the outset in its entirety in the vacuum tank 15 or to introduce this carrier through an inlet into the container and to lead out again via an outlet after the coating, so that each only a certain longitudinal region of the carrier is located in the container. The second embodiment has the advantage that it is possible to operate virtually continuously, whereas in the first embodiment after the final coating of the carrier the vacuum container is opened, a new carrier is used, the container has to be closed and evacuated, and then the glow-discharge conditions have to be readjusted.

The plasma vapor is generated between the anode and a cathode connected to the target, which consists of the material to be deposited or essential components thereof, in the latter case, other components of the material to be deposited, eg in gaseous form, can be introduced into the atmosphere 25 of the vacuum chamber so that they react with the pumped plasma to the anode and thus the carrier transported target material and are deposited together with this. So far, in principle, a single target is arranged opposite the anode. Especially in the case of electrophotographic recording media, a completely useful material is obtained practically only if the coating, ie the thin film, is as uniform as possible over the entire surface of the support in every 30 respects, whereby this uniformity affects both the film thickness and the material composition and the material properties, such as crystal size in a microcrystalline film to relate. It is therefore necessary to monitor and regulate the precipitation amounts and temperature gradients along the trajectory of the carrier, so that even deviations in the precipitation rate and morphological structure of the coating can be compensated. Here, 35 difficulties arise in that the carrier only once passes between the cathode and the target, so that a regulation must necessarily take place before the carrier has left the area of ​​the plasma cloud. To explain the problems encountered it should be noted that not only the exact conditions in the pressure chamber, so the electric field, the applied voltages and the composition of the plasma cloud determine the precipitation rate, and the temperature 40 is an essential factor, but that already This may cause unevenness in the deposited film, that the distance between the support and the target, eg due to the target wear, changes slightly mechanically or a shift of the plasma vapor cloud occurs. Changes in the distance can also occur due to the fact that it is not possible to keep the carrier guided by the plasma completely flat. If the carrier is guided over wheels or drums, then even slight eccentricities in the storage of these parts can lead to changes in distance from the target during the movement of the carrier. Delicate and flexible supports can form waves or bubbles. The migration of the plasma itself may be caused by the current density traveling along the displacement path of the carrier. The reason for this may be an uneven contact bearing of the target material, in which case the current will seek the paths of least resistance between the target and the carrier support through the plasma. Temperature changes in the pressure vessel affect both the local precipitation rate and the morphological structure in this area. It may then happen that islands of amorphous structure with diameters of up to 25 mm are obtained in intrinsically crystalline films and vice versa. Similarly, in crystalline and amorphous precipitates, the formation of appreciable

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Crystals undesirable. The crystals grow in areas where the carrier has been cooled inadequately. Similar errors occur due to waves or bubbles in the carrier. The possible throughput rate depends on the size and shape of the target, the deposition rate and the required thickness of the film to be deposited, which determines the rate of advance and the amount of time the support must be exposed to the vapor plasma. In order to obtain long exposure times at usable throughput rates, targets of very long length have hitherto been used. In particular, this method is used in the manufacture of capacitors. It is difficult to maintain sufficient uniformity in the important conditions since, for example, constant distances between the target and the carried-out carrier can hardly be maintained. An increase in the throughput rate would be practically possible only by increasing the current density, but reduces the uniformity of the coating and still leads to thinner coatings.

For the production of other coated materials, for example for the coating of support material with silver salt emulsions in the immersion process by chemical means, but also for the simple vacuum vapor deposition of articles, fabrics, etc., there are a number of devices. Here, however, other operating conditions prevail and, above all, even small changes in distance can not lead to such large changes in precipitation rate and material structure as in steam plasma coating.

A method of the aforementioned type is characterized according to the invention in that the container produces a plurality of plasma clouds which are successive in its basic shape and the carrier moving from a supply to a collection point in the container has a predetermined, predetermined, is guided in its basic form circular path, where only the radially outwardly facing surface of the support is exposed to the action of the plasma vapors of the successive clouds.

The basic idea of ​​the invention is that the likelihood that an occurring nonuniformity repeats itself in the same way in successive targets in the same relative position to the trajectory of the carrier is so small that it can practically be ruled out. Rather, in practice, minor irregularities will be compensated, so that a uniform coating is obtained. The setting of several smaller targets is of course much easier than the adjustment of a large target. Moreover, the rate of precipitation between successive targets can be monitored so that regulation can be made over the plasma clouds that still have to be traversed.

An elongated narrow beam can often be exposed to the plasma vapor of successive clouds as the carrier travels the web in multiple turns while continuing to travel from turn to turn, moving axially and circumferentially.

In this case, the path to be guided along the carrier, be determined by the fact that a series of adjacent turns is attached, which lie for the most part with the exception of the underlying winding areas parallel to each other on a cylinder jacket, wherein jeweüs in the underlying winding area between the end of and at the beginning of the next turn, a tail, serving as a transition, projecting from the cylinder jacket and preferably hanging loosely, is formed; such that during its movement in the circumferential and axial directions of a cylinder defined by the web, the carrier travels along the path from turn to turn.

A device according to the invention for carrying out the method is characterized in that provided in the outer wall and end walls having a container between the supply and receiving means for the carrier moved substantially in its longitudinal direction determining a circular or cylindrical path in their basic form guides, wherein this orbit one or more arcuate target electrodes for the glow-discharge coating are arranged.

As a guide, a drum may be provided, rest on the outer surface of turns of the wearer.

According to a preferred embodiment, the drum is rotatably driven by a drive means and the windings adjacent to the circumference of the drum are additionally hauled over a transport means in the axial direction of the drum over the length thereof, said transport means having two tubes which are spaced from each other with the surface of the drum cooperatively holding the carrier in turns close to the surface of the drum, in its lower part

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Gap but allow the formation of loosely hanging carrier loops, which are the tight-fitting

Connecting carrier turns.

The rotatable drum may itself be formed as an anode, and there is then provided a cathode consisting of a plurality of target electrodes, each target electrode on its side facing outwardly to the outside of the drum side of the material to be deposited material and the electrodes at a radial distance from the drum and are arranged at a circumferential distance from each other so that their sides pointing towards the drum define an at least partly cylindrical mantle, which has a larger diameter than the drum and is coaxial therewith and in the arcuate gaps between the electrodes and the drum, the plasma can be generated. Anode and cathode are in a high voltage circuit, which keeps the cathode at a high negative bias voltage with respect to the anode. For gap adjustment, the individual target electrodes can be radially adjustable relative to the drum.

According to a development, the drum contains near its surface conduction paths for a heat exchange fluid, which are connected via a line leading through the shaft with the outside of the pressure vessel and outside the container to a supply line can be connected.

In another embodiment, there is at least one turn around the drum in the guide path, the carrier being to a considerable extent engaged with the drum outside during steam plasma coating so as to be supported thereon and its backside shielded from the drum. Another way of temperature control is to provide the guides with a heat absorbing coating.

Further details and advantages of the subject invention will become apparent from the following description of the drawings.

For example, the subject of the invention is illustrated in the drawings. It shows: 1 shows a device according to the invention for the coating of an elongated carrier in the application process in side view, FIG. 2 shows a section through a device for continuous coating in a greatly simplified schematic representation, FIG. 3 again shows a section through a device for coating in the application process, 4 shows a section along the line 4-4 of Figure 3, Figure 5 on a greatly enlarged scale a partial section along the line 5-5 of Figure 2, 6 is a schematic plan view for explaining the operation of the device according to Figures 3 and 4, Figure 7 in a representation corresponding to Figure 3 representation a variant in which no longitudinal displacement of the turns is necessary, Figure 8 shows a cross section through the Device according to Fig.7 and Fig.9 again a plan view for explaining the operation of the device according to Figures 7 and 8.

At the beginning, some clarifications are made to facilitate the understanding of the specific description of the figures. Inter alia, and primarily, the illustrated apparatus according to the method of the present invention is intended to produce an electrophotographic recording medium similar to a photographic film. In order to avoid confusion, however, the term film is used subsequently only for the coating applied in the vapor plasma. As a carrier, a Kunststoffohe can be found with a thickness of 0.125 mm use. This is just an example.

Plasma means an ionized gas held in a constant field or in a radio-frequency alternating field and used to sputter atoms of a material from a cathode-targeting target (consumable cathode) onto a support. In steam plasma coating, a vacuum vessel is evacuated and then provided with a solution of an inert noble gas, eg argon, under low pressure. The container may be made of stainless steel or heat-resistant glass so that it does not react with the material or carrier to be coated. In the container, a target and a carrier holder are present as the cathode and anode, wherein the target with a target holder, for example by brazing, connected and the target holder is usually cooled by a suitable coolant for the purpose of setting a certain temperature. High voltage connections for target and anode respectively Carrier holders are available. By means of a cooling device, the carrier holder can be adjusted to a temperature which is usually different from the target temperature. So far, the carrier holder is usually carried out verstübar to exactly adjust the distance from the target. A vapor plasma coating in the DC field is usually used to process targets from a single conductor material.

For the fabrication of composite composite coatings, which may consist of three or four elements, a vapor plasma coating in the high frequency alternating field becomes necessary.

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If the vapor pressures of the individual elements in a composite target differ significantly from one another, the element with the highest vapor pressure can also be introduced into the vessel as gas. It comes to a reaction of flying from the target to the carrier

Atoms with the gas introduced, so that the surface coating is stoichiometrically correctly assembled. This particular process is called reactive sputtering.

The applied high-voltage field ionizes the noble gas, forming ions of a type that knock atoms out of the target. There are also secondary electrons, which only generate heat and are practically not used. The atoms beaten out of the target fly to the support resting on the anode and are deposited there. Cooling devices are used to compensate for the effect of the secondary electrons.

FIG. 1 illustrates, in a very simplified representation, a device 10 for applying a thin film layer in the insert process. A pressure vessel -12- is provided which is supported by a foot portion -14- secured to the floor. There are various mechanical, electrical and fluid connections with the interior of the container -12- provided for purposes to be described. To indicate the presence of such compounds, a mechanical housing or collar -18- has been provided which is provided in the central region of the container and which supports and protects the various connections. Various schematic representations of terminals have been drawn to lead out of terminal boxes -20 and 22- connected to collar -18- and out of a terminal box -24- at the end of box -12-. The connections, tubes or cables for making the various connections to the interior of the container -12- have been designated overall by the reference numeral -26-.

The container 12 is made of an inert material, with its shape and construction chosen to withstand high negative internal pressures. The container may be made of stainless steel, heat-resistant glass or other material having these properties.

Since the device -10- is intended primarily for a coating in the application process, both a carrier supply and a device for receiving the coated carrier inside the container -12- must be provided. It is necessary to open the container from time to time to remove the carrier subjected to the coating process and to supplement the supply of uncoated carrier. The left end of the container -12- of Fig.l is provided with a flange -28-, which cooperates with a removable closure -30-, so that a pressure-tight closure is achieved. All suitable quick fasteners can be used to hold the flanges close together. It is provided a rotatable drum, which is normally drivable -12- forth from the outside of the boiler. The construction -32- comprises a trolley -34- supported on rollers -35- so that this trolley can be moved on the ground from left to right. On the carriage -34- a motor -36- is arranged, which is connected to the drum, not shown in Fig.l by a hollow shaft, also not shown, which latter leads through a terminal housing -38-. The housing -38- is connected to the closure -30- and similarly carries connections, electrical connections, measuring and control wires, etc. After the closure of the closure -30- from the flange -28-, the entire closure -30- , the housing -38-, the inner drum and the associated devices are moved to the left, with the drum moves out of the container -12-.

Support -40- may contain controls and panels. With -42- are symbolically designated electrical connections that lead through the housing -38- to the drum or other inside the housing -12- lying connection.

In Fig.l and in the other figures, various compounds and connections are provided and shown, which lead out in the longitudinal or radial direction of the container -12-. These include electrical wires, coolant pipes, mechanical connections for target adjustment, instrument connections, couplings, etc. The explanation is simplified by the chosen representation. Normally, it is preferable to guide and support all connections and connections through the shutter -30- or its corresponding part in the other figures. It can, if so desired, the entire closure are removed, with he carries most of the interior design to the outside, so that adjustments, renewals of

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Targets, the splicing or winding new substrate strips on supply rolls, etc. can be made. This should be considered in the assessment of the various variants of execution which are still described.

FIG. 2 is a simplified schematic representation of a flow-through apparatus suitable for carrying out the method of the invention. In this case, a container - 52-- is provided, which is suitably constructed to withstand high negative internal pressures. The walls of the container can be made of stainless steel, heat-resistant glass or the like. be made. The left end of the container is open and provided with a closure -54-, which is equivalent to the closure -30- of Fig.l. The flange connection -56- corresponds to the flange connection -28- and fastening means are again provided which allow a rapid removal of the closure. However, since the continuous process is used, it will not be necessary for the device -50- to frequently remove the closure -54- from the container -52-. This is an advantageous embodiment, since the operating conditions for the vapor plasma inside the container -52- need not be destroyed each time and renewed when a new carrier stock is to be coated.

In Figure 2 is indicated by dashed lines a cylindrical drum -58-, which is connected to a shaft -60-, which is led out through the closure -54- via a pressure-tight, schematically indicated passage -62-. For clarification, it should be noted that the structural details of the component represented by a symbol, for example -62-, are not mentioned, since this_2Q Component can be formed in various ways. The essential requirement to be met by a pressure-tight passage through the container wall -52- or the closure -54- is that the pressure difference between the inside and the outside is maintained. Similarly, there are still requirements in terms of electrical insulation, impermeability to gases and liquids and the need, if necessary_2g To guide mechanical part through the wall or to drive rotating through the wall. The symbol -62- of Fig. 2 will be used in the same or slightly modified form in the various drawings.

The passage -62- of Figure 2 is needed to allow rotation of the shaft -60- from the outside of the container -52- lying area ago by means of a motor -64-, wherein ₃₀ the implementation can also serve to electrical lines, coolant lines and the like. through the interior of the shaft -60- to lead, which is preferably hollow. Symbolically, the grounding line -66- is a type of electrical conductor that passes through the passage -62- though within the shaft -60-.

In Figure 2, a spool is indicated on the left, the supply of an elongated carrier ₃₅ -70- which is to be coated inside the container. The carrier -70- may have a width of 35 mm and a thickness of a fraction of a millimeter. The edges may be perforated as in a conventional 35mm (35mm) film. The carrier -70- can be pre-masked, so that during the coating automatically over the length of the carrier -70- side by side image window defining frame arise. The edges can be made by orders of aluminum as well_4o pretreated to obtain a useful electrical connection in the handling of a carrier to be used in electrophotography. The carrier 70 may be made of any suitable plastic or synthetic resin film which remains stable at the conditions prevailing inside the container 52 and also at those conditions to which the carrier in the finished form of use is subjected.

_4S The support may be made of electrically insulating material, such as an organic polymer, one embodiment of which is flexible polyester.

The carrier -70- enters the container -52- via a pressure-tight passageway -72- which is also provided in the closure -54- and is guided, for example, over a roller 74, so that it engages with the cylindrical mantle surface of the drum. 58- comes into engagement. to_so Explanation, the carrier was drawn in four open turns -76- lying on the surface of the drum -58-, wherein the overall shape is helical, so that the carrier on the left on the drum -58- passes and on the right side of the drum surface - 58- leaves. This is a tortuous guide path that is essentially helical. The further leadership of the now

The carrier coated -78- is determined by a roller -80-, so that the carrier, by means of another pressure-tight outlet -82- in the end wall of the container -52-, reaches a receiving device, eg one of a motor -86 - driven coil -84--, can get. The feeder -68- and the receiver -84- may be parts of a continuous production line which extends over a much larger area than the area shown and in the course of which there are other suitable guiding and processing or treatment devices.

Preferably, the turns -76- are not opened, as shown, but guided so that the edges of successive turns engage each other so that a substantial number of support turns result on a drum. In this way, the carrier -70- is frequently and repeatedly exposed to the plasma vapor generated inside the container -52-.

Carrier -70- travels along the outer surface of drum 58 in a tortuous path which is helical in the apparatus of Figure 2. In addition to the rotation of the coils -76- caused by the rotation of the drum, axial movement also takes place, in this case from left to right. The carrier must simultaneously be pushed to the right or otherwise axially adjusted while performing the rotary motion. There are a variety of devices available to do this. Among other devices may be used, which are used in the winding of wires and yarn. Other suitable methods and devices for moving the coils may be used which impose movement on the coils -76- via outer straps or straps in a manner somewhat akin to winding paper strips against fixed cores in the manufacture of Pipes etc. is applied,

A sliding or periodic shifting of the windings over the surface of the drum is necessary when the tortuous guide path is helical, but in the following a device will be described in which it is not necessary to move or slide the windings.

In Fig. 2, to illustrate the conveyance required to move the turns to the right during rotation, a block -87- is shown, with arrows emanating from this block indicating the direction of the force exerted by it, as required to understand the turns to the right. Any suitable device may be used for this purpose. According to the invention, such a device may also comprise a construction which makes it necessary to modify the drum in order to enable the movement of the windings.

By -88- is meant a target which is either cylindrical or segmented and surrounds the drum at a distance such that a gap for generating the plasma vapor remains free. In a preferred embodiment, the target is energized from a high voltage source via respective conduits, generally designated -92-, which conducts conduits through the wall of the container -52- via another pressure-tight passageway -94- are. The tuners for Target -88 and Drum-58 are not shown. If the drum is grounded or has potential above ground and the target has a very high potential, which is negative, or is effectively negative, as a result of causing corresponding particle motions and collisions, then the target will be a dummy cathode act on an electric field created between the drum -58 and the target -88-. In some instances, the drum is biased to be negative by a few hundred volts with respect to ground potential, thereby somewhat reducing the overall effective field, but on the other hand providing advantages in elevating the dark gap formed upon discharge across the substrate surface becomes. This gives a harder deposit or coating with lower resistivity.

According to a known phenomenon caused by the ionization of an inert noble gas, such as argon, or the like from a reservoir. Is introduced via a pressure-tight passage -98- into the container -52-, ions which impinge on the target -88- and knock out of this atoms, which are subsequently abschleißend to the surface of the carrier -76- driven and these coat. A gas acting as a dopant can also be introduced via the pressure-tight passage or a replacement of used oxygen or another gas can be undertaken. Various targets consisting of oxides give off the oxygen faster than the meta-of the oxide.

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In Figure 2 are again electrical cooling or Meßverbindungen to the interior of the container -52- still

Devices for expelling secondary electrons from the gap -100- shown to keep the view as simple as possible.

Before a description of the remaining figures is continued in detail, the advantages of the construction described so far as well as the operation will be described in detail. As has been explained, the plasma contains a cloud of particles, that is, atoms of a substance to be deposited on the carrier. The cloud is generated by electrical means or by heaters. The difficulties encountered with the previously known constructions in generating a uniform plasma vapor cloud over the displacement length of the support are immaterial in the construction according to the invention, since it is provided according to the invention to suspend the support in many cases over the plasma vapor formed over the length of the target, thereby subjecting the support, for example, to FIG .2 to move from left to right. This results in a uniform coating in the form of a thin film on the exposed surfaces of the support -70-.

Moreover, the thickness of the coating can be easily adjusted and a relatively strong coating can be achieved over a short distance. If, in the embodiment according to FIG. 2, the carrier 70 was pulled out directly in the direction of the coated carrier 78, then the container would have to be formed many times longer in order to achieve the coating time which is obtained because of the winding path. Moreover, the target would have to be correspondingly longer, several connections and connections would be necessary and the device would be much more complicated because of the extra length. Such an additional length would by no means ensure a uniform coating and the throughput rate would be lower than in a construction according to the invention.

It should be understood that the carrier 70 may be provided with one or more coatings beforehand in other devices or throughputs by the device 110-.

Illustrated in FIGS. 3 and 4 is an embodiment of the device 110- which enables the application of a thin film layer to an elongate carrier in the deployment process. Although the device -110- was still illustrated in the sub-scheme, but much more details have been shown as in Fig.l and 2. A pressure vessel -112- has an end closure -114- which is hermetically connected to the left open end of the container -112- via schematically indicated brackets -116-. Container -112- and closure -114- are each provided with flanges which cooperate with the preferably designed as quick-acting fasteners -116-.

In the container -112- is a drum -118- stainless steel or the like. housed, which is rotated and supported by a shaft -120, the latter of which is guided via a pressure-tight passage -122- through the shutter -114-. As already mentioned, the symbol used to represent the passage -122- is not intended to be limiting and may mean any of a variety of passages involving the transmission of energy, motion, electrical power, signals, coolant, and the like. without affecting or changing the atmosphere inside the container. Preferably, here are the most passages and the power lines, etc. passed through the shutter -114-. The shaft -120- is driven by a suitable drive motor -124-, the speed of the motor being controlled as well as the other variables which determine the operating characteristics of the device -110-. Normally, the shaft is hollow and takes coolant lines -126-, electrical cables and the like. on. The coolant lines -126- lead in the illustrated embodiment inside the drum to cooling coils or bellows -128-,

The cooling devices -128- can be designed in the form of turns or according to FIG. 6 also as a chamber. In Figure 4, the cooling devices were characterized by cross-hatching. The coolant, which water or liquid nitrogen or the like. is circulated during operation to keep the carrier cool during the deposition of the thin coating. In fact, temperature, plasma pressure, electric field strength and other parameters are constantly monitored and controlled to achieve the best results, as will be described.

In the left portion of the chamber formed by the container -112- -130- a carrier stock is mounted, which consists in the embodiment of a coil -132-, suitably supported on a block -134-, wherein between coil and Bock a friction clutch -136-

- 9 No. 341335 or the like. may be provided to generate a restraining force thereon during unwinding of the carrier -70-. As in the embodiment of Figure 2, the carrier -70- is uncoated. It may be pre-masked or provided with a conductive edge strip for the purposes already mentioned. Carrier -70- runs in the direction of arrow -138- or is guided in that direction to lay around the surface of drum -118- in a plurality of close, juxtaposed turns. As shown in Fig. 3, the windings abut each other to form loops -140- so that a relatively large number of loops over the axial length of the drum -118- are obtained. This would also apply to the device -50- of Figure 2, where open loops have been shown for better explanation.

When the drum -118- rotates, then the loops -149- also rotate in helical ways and are displaced in the axial direction by means of a grinding device -187-, which in this embodiment corresponds to the component -87- according to FIG. During this traveling movement over the drum surface, the carrier is coated with a thin film and finally guided from the right end of the drum as a coated carrier -78- to a pickup which, for example, is formed as a coil -142-, on which the coated carrier can be wound. The spool -142- is mounted on a block -150- and is driven by a motor -152- which can be powered and controlled by the area outside the container -112- via lines -154-. The connection leading to the outside of the container -112- was not shown, but it is clear that this is again a connection through a pressure-tight passage.

As in the embodiment according to FIG. 1, the operation of the device -110- is terminated when the existing carrier stock -70- has been completely coated and is therefore present as a coated carrier -78-, with almost the entire carrier coming from the coil -132 - was wound on the bobbin -142-. Preferably, a sensor -155-, indicated symbolically, responds when the end of the carrier -70- has been reached and actuates, via a transmission line -157- guided by the shutter -114-, a control device -159- which controls the motor -124- and the device -110- shuts off. Then, a new coil can be used and the carrier end of this coil connected to the end of the old carrier -70-, eg be spliced, so that it is not necessary to re-introduce the carrier. The shutter -114- is then opened using the parts -116- and then the entire drum -118- is taken out with the spools -132 and 142- and the associated devices, these parts again on a carriage corresponding to the carriage -34- are mounted. The full spool -142- is replaced by an empty spool and a full spool -132- is attached to the coated spine to replace the now-empty spool on the spine -134-, with the beginning of the spool of the new spool at the end of it connecting to the drum-wound old carrier leading to coil -142-. Subsequently, the entire car -34- is moved forward again and the shutter -114- closed.

In the embodiment now described, the conditions required to create the vapor plasma within the chamber -130 must be reduced and rebuilt after the new entries of the new carrier. It would be more convenient to continuously guide the carrier through chamber 130 or to provide a pressure lock which allows the coil -132- and its support means to be connected to connect further carrier lengths without destroying the plasma vapor conditions. In this case, the coil -142- would have to be built so that it can hold a large supply of coated carrier -78-. In this case too, the feeler -155- would be very important.

In the interior of the container -112- is a target or, which may be more convenient in practice, a series of targets -156, 158 and 160- arranged. These targets are preferably in the form of cylindrical sectors which are aligned with and equidistant from the barrel -118 so that a cylindrical gap -162 between the targets -156, 158 and 160- and the barrel -118 - is formed. With regard to their mode of action, all three target sectors form a single target or a single cathode, which is why they are also referred to collectively below as target device -156 to 158-.

The target portions are normally formed of a metal back portion having a surface layer or laminate formed from the material to be spattered onto the exposed surface of the support wrapped around the drum. If the final product is an electrophoto- 10 no. 341335 graphic film with a thin film layer of n-type cadmium sulfide, then the thin film mounted in the device -110- is flexible, transparent, inorganic, photoelectric and electronically anisotropic. In the case of cadmium sulfide, the target surface may contain cadmium and the sulfur may be introduced as a dopant into the chamber -130-, the supply from a reservoir (not shown) via a shut -166- and via a pressure-tight passage -168- appropriate amounts can be made so that the precipitate takes place stoichiometrically correct. When the thin film is zinc indium sulfide, zinc and indium in alloyed form the support -164- and the sulfur is supplied in a gaseous state.

Each target sector is supported by suitable supports, eg hollow rods -170, 172 and 174-. Each holder is in communication with the associated target sector, wherein the sake of simplicity, the representation is made so that the implementation of the holder through the container wall via pressure-tight passages -176, 178 and 180- takes place. Preferably, the brackets are passed through the shutter -114-. The brackets are normally hollow in each case and take electrical lines, coolant or the like. on or form even electrical wiring for the operation of the devices. For example, as illustrated in connection with the support -172-, electrical wiring connections -182- or corresponding connections for various electrical devices inside the chamber -130-, so to operate the motor -152- or the tungsten lamp -184-, which will be described, provided. High-voltage lines -186- can also be provided in the same holder -172-. It should be understood that a preferred embodiment of the device of the present invention operates with a radiofrequency field of order kV in gap 162 so that the target portions must be at a high negative voltage relative to drum 118. The bracket -172- may also contain coolant lines -188- that are needed to keep the target compartment cool. The coolant may be liquid nitrogen or a lighter suitable material. Heat exchangers, tubes, hoses or the like. may be incorporated into or closely connected to target parts -156 to 160 and receive the coolant. None of these constructions has been further illustrated.

Since the target parts -156, 158 and 160- consume, it is necessary to be able to adjust them mechanically, wherein the adjustment means must also be provided in connection with the supports -170, 172 and 174-. The adjustment can be made by any suitable means, the adjustment means being indicated symbolically by the dashed line 190 in FIG. Similar connections, connections and mechanical adjusters are used with the other brackets, as indicated by -192 and 194-.

During operation of the device -110-, argon gas or other inert gas is supplied from a non-primed device via a shut-off device -196- which cooperates with a pressure-tight passageway. The argon gas is supplied after a fairly high vacuum has previously been produced. A vacuum pump that has not been primed is used, connected via a shut-off device 20000 and a pressure-tight feedthrough -202-. Typically, the chamber -130- is pumped down to a pressure of the order of 10 torr and the later fed argon raises the pressure in the chamber again to about * 2 x 10 torr. The main events within the chamber -130- take place primarily in the gap -162-. The radiofrequency field ionizes the argon atoms and results in bombardment of the support 164 by them. The atoms of the pad material -164- are knocked out and form a cloud which is driven toward the drum -118- by the negative potential. These atoms deposit on the surface of the drum, which of course is covered by the support 70, so that a coating builds up on the surface of the support. The back of the carrier is protected so that it rests directly on the surface of the drum. In addition to the cooling means -128- for the drum and the similar cooling means for the target parts -158 to 160-, in the device -110- still another type of cooling is used. During the presence of the plasma vapor, secondary electrons are also formed. These secondary electrons also impinge on the carrier and merely lead to unwanted heating of this carrier. In order to expel the secondary electrons from the gap -162-, a high field strength magnetic field reaching across the gap is applied, which is polarized so that the secondary electrons in the axial direction of the drum -118- are expelled from the gap. To generate the

- 11 No. 341335

Magnetic field permanent magnets are used. In Figure 3 is on the through the end wall of the container -112- via a pressure-tight passage -210- guided shaft -208- a permanent magnet -206- supported. Preferably, the cylindrical magnet 206 has longitudinal slots -212- to form the field and concentrate it with opposing pieces of glue 214 arranged coaxially and radially outwardly of the target portions -156, 158, and 160-. The magnet parts -214- are permanently magnetized and cooperate with fixed axially extending parts of the cylindrical magnet -206- along their length. The generated magnetic field is radially directed with respect to the gap -162.

As an example of the temperatures that occur, it should be noted that in a typical device, the target parts reach temperatures of 200 ° C + or - some C °. This requires cooling, for example by water or by another coolant. The support surface should have a temperature of the order of 80 ° C in order to achieve effective deposition and to maintain the integrity of the support -70- throughout the coating process.

During the mounting of the thin film on the support, shrinkage of the support will occur to some extent even if pretreated. In known coating devices shrinking led to difficult solvable problems. In the embodiment according to the invention, the shrinkage leads to a firmer contact of the support on the drum --118- or on the drum -58- according to FIG. As mentioned, when the tortuous path followed by the carrier is helical, it is necessary to translate or slide the coils axially over the surface of the drum. Heavy shrinkage can make this difficult to do, but if performance is possible, shrinkage helps to achieve a uniform coating because it prevents the formation of waves and blisters of the backing during the coating process.

An embodiment which avoids the difficulties resulting from the shrinkage and in which only the simplest means for advancing the windings are necessary, will be described in the following in connection with FIGS. 7, 8 and 9.

During operation of the device according to the invention, since the carrier 70 and also the thin film deposited thereon are transparent or at least to a very high degree translucent, the thermal radiation can be radiated from the target parts both through the thin film and through the carrier. which radiation can be reflected from the surface of the drum -118- into the carrier -70-. This leads to an increase in the heating of the carrier.

According to the invention, a thin surface, which is heat-absorbing, is preferably provided on the drum -118-. For example, if the drum is made of aluminum, then its surface could be anodized (FIG. 5) . With a stainless steel drum, any suitable black coating can be applied which absorbs the infrared rays passing through the support and transfers the heat to the cooling means -128-. In Fig. 5, the cooling device is shown as a chamber formed in drum -118-, with the support of greatly increased thickness drawn to show a thin film coating -222- formed on its surface. It should be understood that more than two thin films may be provided. The black coating should be stable for all conditions encountered in chamber -130-. Black nickel or other metal deposit plated on the drum -118- would be suitable for a stainless steel drum.

When the aimed end product forms an electrophotographic film comprising an electrically insulating plastic film as a support, a thin film layer of ohmic material which is electrically conductive in the natural state, and for example indium oxide in a thickness of 500 Å, and a photoelectric layer having a Thickness of about 4000 Å, then it is necessary to subject the support twice to the coating process to obtain the two coatings. Thus, it must be made clear that the carrier -70- of Figure 3, although it may be addressed as uncoated as far as the device -110-, previously provided with a thin film layer or even several such layers in another plasma evaporation may have been, as already mentioned.

To give some practical information regarding the device, it should be understood that a typical device -110- may have a power consumption of the order of 100 kW. The

- 12 No. 341335

Drum -118- will have a diameter of 1 meter (40 inches) and gap -162- will be about 2 inches.

The monitoring of the operating state is achieved by various sensors, which are arranged at different locations within the chamber -130-. Connections for electrical cables or cables for the transmission of signals are shown at -230, 232 and 234- in Fig. 4, each connection being shown passing through the wall of the container -112- via suitable pressure-tight bushings -236, 238 and 240- is performed. Preferably, all of these passages are provided in the shutter -114-. Some of the measurements to be made relate to the thickness of the thin film, pressure differences, temperatures of various parts, surfaces and components. Sensor lines can be accommodated in each of the supports -170, 172 or 174-, by the shaft -120- or the shaft -208- or by their own connections or cables that pass through the wall of the container --112-- or the closure -114- pass.

During sputtering, an electron charge builds up on the surface of the thin film layers. This building electron charge may also contain metastable neutral substances, slow electrons, argon atoms, etc. The presence of such a charge may adversely affect the deposition rate and the uniformity of the deposition, which is particularly the case when the constituent charge is localized, that is, restricted to certain areas. This charge can be easily and quickly removed by being neutralized by photons generated in the chamber. For this purpose, a tungsten filament lamp -184- is provided in an explosion-proof enclosure, which lamp remains on throughout the process. The charge reduction takes place continuously, so that there can be no charge increase.

Here's a lot to be said about the monitoring and control of the described method.

Some techniques of the method are known and other aspects are again peculiar to the particular type of coatings used to construct the electrophotographic film described above.

The temperature in tanks -12, 52 and 112- must be kept within narrow limits for best results. This is achieved by monitoring temperatures, gauges and instruments and passing on the information obtained to automatically regulate the temperatures. For example, in certain precipitated materials the crystalline structure becomes most uniform at 80 ° C, the crystals typically having a diameter of 0.1μ.

The plasma vapor pressure and the electric field strength determine the deposition rate. These are constantly monitored by appropriate meters and the information obtained is used to control the delivery of the noble gas and the vacuum pump or, generally, the pumping. Other measured variables are also measured and used for control purposes.

It is clear that a great deal of the technical knowledge and experience required in connection with a device of this kind was not presented or explained, since these empirical values ​​are based on conventional knowledge and can always be obtained by experts. Many refinements can be made. For example, the mechanical support of the drum and the cylindrical magnet can be refined, even if they are supported freely supported on their brackets in Figure 3. Supporting rings -249- disposed between the inside of the drum -118- and the outside of the cylindrical magnet -206- were shown. Such support means will bear against one or the other of the opposite parts, which then engage when telescopically telescoped.

A schematic representation of the drum -118- is shown in FIG. 6 with the supply spool -132- and the take-up spool -142- according to FIG. 3, which is essentially a top view. Block -87- extends the entire length of drum -118- to indicate that in this case the helical path of the carrier is helical and there is a need to translate loops -140- axially in the direction in which they travel would also normally be brought by the rotation of the drum over the entire length of the drum. For example, if a finger or other periodically-slipping member is attached to the left end of the drum as the winding shifter, then the force exerted by it must apply to all turns

- 13 No. 341335 of the drum -118- be transferred simultaneously to move them simultaneously with the supply of the carrier to the drum.

The path of the carrier -70- is indicated by the dashed line -244- and can be traced around the entire drum -118- due to the arrows drawn. For example, in the

Area 244-1 the first turn behind the drum and comes out at 244-2, goes around and down to start the second turn at 244-3, comes out at 244-4, etc. The short arrows -246- suggest the application of a force applied axially to the right on windings -140- by the winding device -87-.

The description thus far deals with all essential details in an easily understandable manner. The movement of the carrier in a tortuous path along the drum from one end to the other should be sufficiently clear in the context of those cases in which the trajectory is helical. However, it should be made clear that the practical embodiment of the embodiment described so far is much more complicated than it appears on the basis of the drawings and explanations. The main cause of such a complication is the turn-wrap device, generally designated -87-. This device is particularly affected since the drum surface is preferably perforated to allow for easy cooling and because longitudinal displacement of the support in the axial direction is not always practical. This is especially true in the case where the carrier is relatively thin and delicate. A practically cheaper and simpler training is described in connection with the Fig.7, 8 and 9 below.

In FIGS. 7, 8 and 9, where appropriate, the same reference numerals are used as have been done in connection with the device 110.

The device according to FIGS. 7 and 8 has been generally designated -250- and has been shown in an embodiment which, as in the case of FIGS. 3 and 4, provides for operation in the deployment method 25. The supply and take-up spools could also be provided on the outside of the device, which would then operate continuously.

The device -250- differs from the device -110- primarily by the construction of the means for shifting the windings. In practically all other areas, it is essentially the same. Accordingly, operation and mode of operation 30 as well as the structure of the overall system can be assumed to be described in connection with FIGS. 3 to 6.

The supply and take-up spools -132 and 142- are normally located closer to the bottom of the chamber -130- than in the embodiment of the device -110-. Moreover, the axes of these coils are substantially parallel to the axis of drum -118- so that the uncoated end -70- of the carrier and the coated end -78- are each guided in tracks which are normal to the axis of the drum. extending levels lie. The coils were mounted on a foot part -252- which can be hollow and can carry electrical leads to power the various motors, etc. For example, a leg -254- connected to the shutter -114- receives the ends of electrical leads -154- which are passed through a pressure lock -156-. The bobbin -132- will be provided with a braking device -136- and the bobbin -142- with a drive motor -152- which is supplied by the through the hollow foot part -252- leading connections -154-. Also in the device -250-, the turns -140- are tightly wrapped around the drum, but despite the tortuous overall guide path and the tortuous movement of the carrier, all turns on the drum are parallel to each other and normal to the axis of the drum -118-. The 45-turn slider -87- includes a device that guides a short portion of each turn in the lower portion of the drum -118- from one turn to the next turn.

The bottom of the drum -118- has two stainless steel rollers -258 and 260- in firm engagement, which rollers are rotatable. The pressure roller -258-, which is not visible in FIG. 7 but is shown on the left in FIG. 8 -> is an idling roller, but which is pressed firmly against the drum -118-. It is normally stored in a block or foot part which has not been illustrated in the drawings, but may correspond for instance to the foot part 262 which carries the left end of the roller 260. This foot part and those foot parts which hold the pressure roller are in the

Normally connected to the base -252-. The second roller -260- forms a leading role and

- 14 No. 341335 extends between the foot part --262-- and the roller drive -264-. She is stuck with the

Bottom of drum -118- engaged. It was spoken of a leading role, as it was from the

Drive is driven at such a speed that it tends to rotate faster than if it were driven directly by the drum -118-.

The uncoated carrier -70- is withdrawn from the spool -132- against the retention force of the device -136- and introduced on the inlet side between the roller -258- and the drum -118-. It runs exactly cylindrical around the drum, thus describing a rectilinear path that is coaxial with the drum. The two ends of this loop are in the axis of the drum normal plane. On the roller -260- this first turn of the carrier -70- enters the inlet gap between the roller -260- and the surface of the drum -118- and exits at the outlet gap.

At this point, a hanging loop, crease or bend is provided, designated -266- and hanging loosely between rollers -258 and 260-. It begins at the outlet gap between the roller -260- and the drum -118-, forms the loop and then enters the inlet gap between the roller -258- and the drum -118-, but here is at least the width of the carrier - 70- shifted so that it represents the beginning of a second turn around the drum. Thus, the loop is slightly cranked. But as it hangs loose and the carrier is quite flexible, this carrier follows without difficulty in the cranked offset position. It will be repeated that the first turn begins on the reel, passes around the reel and, after the passage of the reel 260, forms the first hanging loop 266 which begins at the end of the first turn and at the beginning of the second turn Swirl ends. Only the first loop was labeled -266-. The following loops were commonly designated -268-.

There are as many loops as there are turns -140- with each loop loosely hanging down and long enough to allow easy rotation of the carrier following the contour of the loop to the beginning of the next turn under the pressure roller He wanders.

The pressure roller -258- is pressed firmly against the drum -118- and restrains the carrier -70-, trying to pull the carrier firmly against the surface of the drum -118-. The leading roller -260- is driven at a slightly higher speed than would be necessary for a direct rotation transfer from the drum -118-, and thus tends to pull the carrier even more firmly against the surface of the drum -118-. Thus, each turn of the carrier is held snugly against the drum with the hanging loops falling loosely beneath the drum -118. The turn-to-turn shift is no longer required around the entire drum and along the entire drum length, but only needs to be done in the hanging loops, where it becomes a simple matter because of the loose guidance and flexibility of the wearer.

The last or nth turn of the now coated carrier -78- around the drum exits the discharge gap between the roller -260- and the drum -118- and is received directly on the take-up reel -142-. The take-up spool drive motor-152 -142 is provided with a corresponding means to keep this support stretched.

The rollers -258 and 260- may be cambered towards their longitudinal center to compensate for longitudinal bends and to keep the pressure against the drum everywhere sufficiently large to achieve a firm pressing of the turns to the drum. This is supported by the low shrinkage of the carrier. The loops are sized to extend a sufficient length, for example about 16 cm (six inches), for a drum of about 1 meter diameter, so that slight deviations do not remove so much from a loop it comes too close to the drum, so that in any case the twisting and shifting is possible. Slipping on the drum itself is virtually impossible. It can be assumed that the thin deposited film is so hard that the rollers -258 and 260- hardly scratch this film. Simple monitoring devices may be provided which respond to unusual shortenings of each of the loops and then shut down the device.

Reference is made to Fig. 9, which shows a simplified view to assist in explaining how the rollers -258, 260 and the hanging loops are used as means for

Moving the windings work.

- 15 No. 341335

The carrier -70- is withdrawn from the supply spool -132- and partially runs around the RoUe -258- at 140-1 to begin the first turn. It passes over the top and top of the drum at 140-2, up over the apex of the first turn, and then travels down and partially around the leading roller -260- at 140-3. Then the carrier forms⁵ the first hanging loop -266- which is crimped to the right as shown and again partially around the pressure roller -258-, as indicated at 140-4. Then it forms the second turn, moving on the web 140-5 and coming back down under the drum -118- and partially at 140-6 around the pre-roll -160-. Here, the second turn is completed, and now the second loop 268-2 is formed which extends so as to bring the support partially around the roller -258- in the area intended for the third turn. The third turn continues at 140-7 just past the pressure roller -258- and passes over the top of the drum at 140-8. The carrier re-runs around the bottom and at 140-9 partially around the roller -260-, after which it forms the third loop 268-3. This process continues until finally the last turn 140-10 has been formed and the now coated support -78- at 140-11 partially around the

Roll -260- and directly on the take-up spool -142- is performed.

Some remarks are also to be made regarding the construction of the target parts -88, 158- and so on. The actual parts may be plates, strips or even bars arranged in an arc shape so as to form something which in effect acts as a surface. If the target is made up of a plurality of rods, then its renewal is simple and economical, and it is also possible to arrange rods of different material side by side in any desired quantitative ratio to meet the requirements of coating with alloys, compounds and the like. to suffice. Accordingly, the reference to arcuate parts will also comprise bar rows, strips or plates arranged in an arc shape. When using

Rods may be hollow and lead in their interior a coolant.

Many details have not been explained in the above description, as they are in the state of

Technics are known. The exact mechanical and electrical components and their construction need not be explained to those skilled in the art. The number of carrier turns may be varied depending on the requirements of the devices, but may typically be 10 turns of about 1 meter in diameter. The engines and drive equipment must be

Requirements of the device in terms of performance, heat dissipation and dissipation, corrosion and lubrication, etc., meet. The electrical design must take into account the frequencies and voltages that occur and the current densities to be handled. For example, at least in the United States of America and many other countries, it is necessary for the targeting frequency to be 13.56 megahertz. This type of electrical energy must be over³⁵ special cables and connections are guided. It must also be taken into account the problems of shielding. Tuning capacitors for the targets and the drum for the adjustment to these frequencies should be provided.