DK149926B - sputtering - Google Patents

Description

o in 149926

This invention relates to a cathode atomizer of the kind set forth in the preamble of claim 1.

Such cathode atomizers are known from, for example, DE-OS 2,400,510. They comprise a pressure vessel s having at least one cathode measuring electrode as well as a flexible substrate (substrate) delivery device, e.g. polyester film, and a winding device for the coated substrate. Furthermore, suitable operating control and monitoring means are provided. The support is passed over a rotating anode over a spraying plasma which is formed in the container. The target electrode material is atomized in the direction of the anode. As the anode is covered with the substrate, the material is deposited as a coating on the substrate.

Auxiliary apparatus, supply means 15 and controls are provided for providing the ionizing gas and its mixed components and for monitoring and controlling the supply to the chamber, for supplying electrical energy to the apparatus and monitoring and control thereof and its effects, for control and measurement. speed, temperature and thickness of the deposit and many other parameters, to operate the substrate and its advance and monitoring and control of its voltage, etc.

It is also known to surround the atomization cathode with a shield and hold this shield at the same potential as the container and the atomizer chamber (DE-OS 2.115.590). In this way, the anode is at the same potential.

DE-OS 1,515,322 discloses a cathode atomizer, in which the anode is held at a potential different from a base electrode.

30 It has been found that the conditions for depositing certain materials, especially photoconductors on thin, flexible, translucent substrates, include, among others: (a) the anode must rotate; (b) the energy supplied must be coupled to the cathode; 35 the anode and the shield in the vessel by means of an electrical circuit or network where the cathode is at the maximum negative voltage, the screen is at ground potential 2

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149926 and the anode are at a potential that is also negative with respect to soil but to a much lesser extent than the cathode; (c) the cathode surface must be temperature controlled to prevent excessive heat loss during the cathode sputtering.

5 Certain other requirements of the apparatus make the attainment of the above conditions very difficult to provide, and these requirements include: (d) all supporting structures of the apparatus including the chamber walls shall be kept for earth potential for practical and safety reasons; (e) the ends of the drum shall be screened for; preventing excessive deposition thereon, and (f) the substrate-carrying portion or conveying means of the apparatus must be moved into and out of the chamber when the cathode atomization is to be initiated or completed, respectively.

SUMMARY OF THE INVENTION It is an object of the invention to design a cathode atomizer of the type initially referred to in such a way that the substrate can be applied to a small negative voltage. The stated object is achieved with a cathode sputtering apparatus of the kind specified in the preamble of claim 11 which according to the invention is peculiar to the design according to the characterizing part of claim 1.

Hereby the drum anode is obtained at a different potential than the surrounding atomization chamber and so that it operates at a small negative bias, which is especially advantageous for coating with certain photoconductive materials by high frequency atomization. Furthermore, it is an advantage that the described apparatus has a shield at the drum anode end.

The invention will now be explained in more detail with reference to the drawing, in which: 1 is a side view of a cathode atomizer according to the invention in closed condition; FIG. 2 shows the embodiment of FIG. 1 in the open state, FIG. 3 is a schematic sectional view of the plane 3-3 of FIG. 2 set 3

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Fig. 149926 in the indicated direction to illustrate the path of movement of a substrate on the transport arrangement; 4 is a schematic perspective view of the transport arrangement; FIG. 5 is a section through a portion of the chamber along line 5 5-5 of FIG. 2 in the direction indicated by the arrows; FIG. 6 is a perspective view of the embodiment of FIG. 5 shows the part of the chamber, FIG. 7 is a detailed section through the lower part of the drum anode of the apparatus of FIG. 1 to indicate the manner in which contact is made to the same; FIG. 8 is a block diagram of the electrical circuit of the cathode atomizer of FIG. 1, and FIG. 9 is a more or less schematic section through a modified apparatus.

15 The embodiment of FIG. 1 to 8, the cathode atomization apparatus as a whole is designated by reference numeral 10 and comprises a fixed foot or support frame 12 having rails along an upper edge, a housing 16 mounted on rollers or wheels 18 in engagement with the rail 14, a pressure vessel or a chamber 20, carried by the frame 12 by means of fixed stands 22, and various other parts to be described later. The housing 16 has a transport arrangement 24 mounted on its left end supported on a suitably projected subframe 26 which is attached to the forward wall 28 of the housing 16.

The wall 28 carries a circular sealing system 30, and the transport arrangement 24 and its subframe 26 are designed to be surrounded by the cylinder formed by a projection of the sealing system 30. The pressure chamber or container 20 is closed on all sides other than at the right end where a flange 32 is provided and arranged to seal against the abutment 30. In FIG. 1, the apparatus is shown in its closed state, with the cabinet 16 being rolled forward to the left thereby leading the transport arrangement 24 into the chamber or container 20, the assembly represented by the flange 32 and the sealing system 30 being hermetically rendered at using an appropriate packing and locking arrangement. In FIG. 2, the apparatus is shown in the open state, and the enclosure 16 and the chamber or container 20 are separated and provide access to the transport arrangement 24 and a support 5 supported thereon and to the interior of the chamber 20.

The depicted transport arrangement 24 does not show drive and control mechanisms contained in the cabinet 16, which are, for the most part, mounted on the back of the wall 28. Their more detailed construction is subject to wide variations, and such details are not relevant to the invention. , although they may be considered necessary for the operation of the device. The enclosure also contains all apparatus and all parts necessary for the operation of the entire apparatus, which include speed controls, drive mechanisms, pumps and ducts for operating heat exchange fluid, a large number of measuring instruments for temperatures, pressures, currents and voltages, etc. The outer wall of the cabinet 16 is, as shown, provided with a number of pushbuttons, measuring instruments, lamps and the like, but only in a symbolic way.

20 The chamber or container 20 is, as shown, provided with gas connection indicator 34 and 36, an electrical board 38, pipes and wires 40, electrical wires 42, push buttons, measuring instruments, etc. Viewing windows are indicated by 44.

All of these things are also symbolic. The apparatus requires considerable control and monitoring, as will be known to those skilled in the art, and the nature of the monitoring, operating and controlling apparatus will vary according to the needs of the apparatus.

Basically, for the operation of a cathode sputtering machine, there are necessities that must be provided, controlled, monitored and frequently recorded. There are phenomena that need to be measured and observed, and in short there are many parameters. High frequency energy must be provided to the targets, which requires adaptation and control circuits, wires and often cooling means. In the latter respect, the refrigerant for the target, since it is in the chamber or container 20, must be provided in the chamber and the refrigerant must be fed and stored.

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circulated. The chamber must be pumped out, which requires vacuum pumps with associated regulation, control and measurement, gases for ionization and background must be introduced, which requires regulation, control, measurement and proportioning.

It is believed that these parts necessary to achieve the functions of cathode sputtering are provided as described, and consequently there is no need to show them in more detail and describe them further.

The projected support frame 26 is shown in FIG. 2, but 10 is understood to provide support for the transport arrangement 24, although not shown in other figures. There is an outer plate 46 and with this associated supports 48, which are again connected to the wall 28 but within the boundaries of the plant 30. All of the rollers and drum to be described are mounted for rotation, either driven or free-running, between the plate 46 and the wall 28.

In FIG. 3 and 4, the transport arrangement 24 is shown, but without the bearings and supports shown, and also without the drive, clutch and braking mechanisms which can be used in connection with it, are shown, the latter elements as explained in the housing 16 being shown. The substrate to be coated is designated 50 and is shown to be transparent. In the preferred use of the apparatus, the substrate 50 forms the basis of an electrophotographic film which is sprayed onto inorganic coating. In that case, the substrate 50 is a synthetic resin sheet material, such as polyester having a thickness of approx. 0.12 to 0.25 mm. Several hundred meters of this material can easily be mounted on a spool or wheel and contained within the apparatus 10, atomizing 30 along its entire length. Such a coil or reel is shown at 52 and constitutes the supply within the apparatus. It is mounted on a shaft 54 which is preferably driven by an appropriate drive motor, but is controlled by a voltage coupling which receives feedback information from speed measuring and control devices, all contained in the housing 16.

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6 149926

The substrate strip 50 passes over a free-running roller 56 guiding the stretch to the drum 58 constituting the anode of the cathode atomizer 10. In FIG. 8, it is seen that the substrate 50 passes around the drum 58, which also rotates, 5 normally free-running, in the proximity of the dimensions 60 and 62, which are disposed at the bottom of the chamber or container 20, as will be described later, and then pass upwards. to another free-running roller 64, from which it is guided around a winding roller 66 driven from the interior of cabinet 16 by a suitable 10 drive motor. Since the diameters of the substrate rollers on the supply coil 52 and winding coil 66 vary inversely with each other during the cathode sputtering, and it is essential that the movement of the substrate 50 relative to the dimensions is uniformly and carefully controlled, an appropriate variable drive must therefore be provided.

Measurements 60 and 62 are shown in FIG. 5, 6 and 8. The chamber or container 20 is in the form of a cylindrical shell 68 with an end bell 70 coupled to the conduit 36. All of the chamber or container 20 parts are made of stainless steel and are held for earth potential for safety reasons.

It is relatively simple to make the container of this material rather than to make it of glass or other insulating material. Measurements 60 and 62 are mounted in measurement units 72 and 74, each consisting of a metal screen 76, 25 mechanically mounted on the bottom of the shell 68 by means of brackets 78 and cooled by refrigerant circulating through the walls of the screen 76. The wiring for the refrigerant is passed through the shell 68 by means of housings which also provide passage for electrical coupling elements for coupling the targets to the energy supply. The location of the targets relative to the drum 58 can be set when the targets are consumed. An adjustable structure in which such an adjustment can be obtained may be contained in the housings 80 or may be provided by settings on the brackets 78, 35. Each target 62 is formed by a plurality of plates or plates, as shown at 82 in FIG. 6, and which is cemented to a suitable metal baking sheet, usually stainless steel. The faces of the target plates 82 facing the drum 58 may be flat or curved. They are generally arranged to form a cylindrical surface coaxial with the drum 58 when in a position adjacent to the targets and the apparatus is closed. Each of the targets 60 and 62 is spaced apart from its screen 76, leaving a gap surrounding the target itself. Background gas is introduced into the space behind each target by means of conduits 84 which pass through the wall of shell 68 and project from the spaces around the targets to bathe the surface of the targets.

The target plaques are preferably formed of sintered elements of the material to be atomized.

Between the measuring units there is a stand 86 carrying 15 one or a collection of brush or tow contacts 88. These are coupled to a portion of the electrical power supply circuit by means of electrical wires passing through the shell 68, as will be explained later. These contacts are preferably mounted with resilient carrier springs pushing them to the right in FIG. 2 and 7. Like dimensions 60 and 62, they must be insulated from shell 68.

Before describing the design details of the drum 58, the operation of the energy supply circuit used by the apparatus 10 must be described. Referring to FIG. 8th

25 The construction of the drum 58 will be better understood when the energy supply circuit is known.

In FIG. 8, the energy supply to the apparatus 10 is shown in its most basic schematic form. A high voltage energy source is shown to the left as a block 90. The source 90 30 is coupled to the apparatus 10 by means of one adaptation network 92 shown with two output lines 94 and 96. The highest voltage, e.g. of the order of 3000 volts at a frequency of 13.56 MHz occurs on line 94 and is passed to targets 60 and 62 and acts as a voltage relative to 35 ground. Line 96 is at ground potential. All screens in the apparatus 10, represented here alone by the drum 58, 8 and screen 76 and the drum screens, are at ground potential, but not the drum itself. The output of the adaptation network 92 is led to a voltage divider which, in the example shown, consists of two impedances Z1 and Z2 coupled across wires 94 and 96. In practice, these capacitors and part of the voltage divider can take into account parasitic capacitance paths. that may have any bearing on the current frequency. The wires may be high frequency waveguides, a coaxial cable, shielded wires, etc.

10 The voltage is divided according to the two reactances of Z1 and Z2 respectively. Drum 58 is connected to terminal 100 between impedances Z1 and Z2 by means of a conduit 98. In order for the drum 58 to rotate, the previously described contacts 88 are provided to enable the drum to be held at a potential different from ground. The electronic effect of the cathode sputtering in the apparatus 10 is as a diode, so that an effective unidirectional effect occurs. The cathodes are targets 60 and 62. and these are kept at a very high negative voltage, which in the given example is -3000 volts. This is in relation to earth which constitutes the maximum positive voltage of the plant, corresponding to zero volts.

In general, the anode is at ground potential and the substrate is laid on it. Here, only the shielding is at 25 ground potential. The anode is the drum 58, and it is held at a voltage which is also below ground potential, but not at a value as high as targets 60 and 62. In the practical example, the voltage at the drum is kept at a value about 50 volts or less, i.e. -50 volts. This is achieved by appropriately designing the voltage divider string Z1 and Z2 and other parts of the circuit, as is well known to those skilled in the art.

The drum 58 must rotate and be made of metal so that it can be easily manufactured and will have 35 the strength necessary to meet the requirements of the cathode sputtering apparatus, it must be stored during use Λ 9 149926

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of mechanically durable bearings, shafts and supports, and further, at least its outer layer must be at a voltage different from that of its surroundings. Another requirement for the drum is that its outer layer must be subjected to temperature control by means of heat exchange fluids. Thus, in the practical embodiment of the invention, it has been considered necessary to heat the outer layer of the drum with the aid of oil to keep it at a temperature of approx. 150 ° C.

All of these requirements are met using the 10 shown in FIG. 7. The body of the drum 58 is formed by an inner metal cylinder 102 by welded end flanges or rings 104. Metal end caps or plates 106 are secured to the cylinder 102 by spaced circumferential screws 108. An outer coaxial metal cylinder 110 forms the outer peripheral layer. of the drum 58 and welded to a telescopically arranged coaxial metal cylinder 112 to form a chamber between these cylinders 114. The cylinders 110 and 112 are connected by metal rings 116 welded to each of them 20 and if the left metallic end is free as shown.

The chamber 114 contains the heat exchange fluid 118 either in the form of substance which fills the entire chamber, or by means of windings not shown wrapped around the interior of the chamber. These are connected to the hollow shaft 122 (Fig. 4) by appropriate wires, such as shown at 120, by which they are connected to a source of such liquid. The wires are shown at 120 '. Since the liquid is normally oil or an insulating liquid, there is no problem in providing an insulating coupling or insulating couplings for conduits 120 or 120 'such that the layer 110 is electrically insulated from the rest of the drum 58, shaft 122, etc.

The rings 116 and plates 106 are radially spaced apart to provide an annular gap 35 at each end of the drum 58 as shown at 124. A cylinder 126 of polytetrafluoroethylene or other stable insulating material is formed by machining and is disposed between the cylinder 102 and the cylinder 112. Its ends are machined to a smaller thickness than its body so as to form shoulders 128 and 130. The resulting axial ends 132 have thereby the same thickness as the annular space 124, and the cylinder 126's axial length is made identical to the overall length of the drum 58 such that it aligns with the outer ends of the plates 106 and rings 116.

Thus, a composite cylindrical element is provided, the outer layer 110 of which is insulated from the rest of the drum 58. The drum is held together by a plurality of screws 134 passing through washers 136 of the same insulating material and spaced apart from each other along the periphery of the ends of the drum. The discs 136 are inserted into deep recesses 138 which are drilled into the ends of the drum 58 and a portion of each recess resides in a plate 106, a ring 116 and an axial end 132.

In this way, the parts are locked against relative peripheral movement, in addition to the washers 136 and screws 134 holding it together.

The ring 116 at the left end of the drum 58 is arranged in such a way that, when the apparatus 10 is in the closed state, the contacts 88 touch and slide on it, thereby establishing electrical contact therewith.

The ends of the drum 58 are shielded as shown at 140, 142, 144 to prevent material cathode atomization on other 25 parts of the drum as the substrate 50 is passed around the lower portion of the layer 110 and is coated here. The plasma representing the cathode sputtering is indicated at 146. Such shielding is carried by the wall 28 and the subframe 46, e.g. by coupling the connections shown in FIG. 2, 3 and 4 with 147 30 designated consoles. It can be seen from FIG. 7, that the shielding elements 140, 142 and 144 are near the ends of the drum 58 leaving a passage for the substrate strip 50 and providing an opening allowing the contacts 88 to slide on the ring 116. Said shield elements 35 lie on ground potential and touch nowhere the drum layer 110.

An altered embodiment of the apparatus according to the invention, which is particularly useful for smaller projects, is shown in FIG. The cathode atomizer 200 comprises a chamber 210 having a cover member 212 intended to abut and lock in place on a flange 214 of the chamber 210. Sealing is provided by a seal 216 located between the flange 214. and a flange 218. The cover member carries a supply coil 220 and a winding coil 222 mounted on shafts 224 and 226. The shafts are driven by motors 228 and 230, 10, respectively, controlled from the exterior of the apparatus 200.

Cover element 212 carries a coupling 232 into which a drum 236 is suspended. The drum is in this case metal and the entire drum is insulated from the chamber 210 and the cover element 212 by suitable insulation provided in the coupling 232. It is mounted on a shaft 238 passing through the coupling 232 and driven by a motor 240 mounted on top of cover element 212. A chain and a sprocket as shown at 242 provide the coupling to shaft 238 without shorting the drum to ground. Appropriate 2Q insulation for this is provided. A ring 244 on the shaft 238 is electrically coupled to the drum 236 and is insulated from all other parts of the apparatus 200. An electrical connection 246 to contacts 248 corresponds to line 98 and contacts 88 of FIG. 8th

The drum is hollow and has a hollow center channel 250 which forms coaxial chambers 252 and 254 which are connected to a tube 256 running around the layer 258 of the drum 236 in its interior. Heat exchange fluid enters and circulates by means of chambers 252 and 254. At the top, it is seen where a suitable coupling can be attached to allow rotation of shaft 259 using pivotable fluid couplings. These are not shown.

The target 260 of this apparatus 200 is a simple plate of photoconductive material mounted on a holder 262 coupled by means of the element 264 through the wall of the chamber 210 to a source of high voltage radio frequency 266. It is not necessary to show the circuit of FIG. 8, assumed to be 149926

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12 is used in conjunction with apparatus 200.

There are screens 268, 270 and 272 on ground potential adjacent to the drum 236, the drum carrier on the shaft 238 and the target 260. The cathode atomization plasma is produced 5 in the same way as with the apparatus 10 using a suitable high frequency energy and a suitable background gas which is allowed e.g. . by means of conduit 274 in the gap 276 between the layer 258 of the drum 236 and the front of the target 260.

Claims (11)

A cathode atomizer comprising: (a) a metallic container (20 and 210, respectively) closed with a metallic closure (28 and 212); and (b) at least one in the container's inner target (60.62 and 260, respectively) and a a drum anode (58 and 236, respectively) having a metallic outer layer (110 and 258, respectively), the drum anode being pivotally mounted to the closure relative to the at least one target when the closure is in its closing position; c) a conveyor arrangement (24) for feeding a flexible substrate (50) over the drum anode through the atomization plasma formed between the at least one target and the drum anode, and d) a controllable high frequency electrical source (90) associated with the drum anode and at least one target, characterized in that e) closed (28 and 212, respectively) and the container (20 and 210, respectively, held at the same potential as a screen (at least one target (60.62 and 260, respectively)) (76,140,142,144 and 20,268,270,272, respectively), (58 and 236, respectively) relative to closed (28 and 212, respectively) ) and the container (20, respectively). 210) electrically insulated metallic outer layers (110 and 258, respectively) are applied a voltage different from the voltage of the screen. A cathode atomizer according to claim 1, characterized in that at least one target (60.62 and 260, respectively) is applied to a negative voltage of about 3000 V, while the metallic outer layer (110 and 258) of the drum anode (58 and 36, respectively) is applied. has a negative bias of about 50 V. Cathode sputtering apparatus according to claim 1 or 2, characterized in that the metallic outer layer (110) of the drum anode is supported by an inner, grounded and in relation to this electrically insulated drum body (102, 104, 106). Cathode atomizer according to claim 3, characterized in that the inner drum body (102,104,106) U9926 0 is attached to the closure (28) and is grounded therethrough, thereby providing an annular space between the inner drum body and the metallic outer layer for insulation. (124). Cathode sputtering apparatus according to claim 3 or 4, characterized in that the inner drum body (102, 104, 106) and the metallic outer layer (110) consist of metal cylinders which are separated by an insulating material (126) between them and which form an insulating material. compound 10 cylindrical unit. Cathode atomizer according to claim 1 or 2, characterized in that the drum anode (236) is fixed to the closure (212) by means of an insulating coupling (232) such that the drum anode is rotatably mounted on the closure but is electrically insulated from the closure . Cathode sputtering apparatus according to claims 1-6, characterized in that a metal ring (116) 20 is provided for applying a voltage different from the voltage of the screen to the outer layer (110 or 258) of the drum anode (58). associated with the metallic outer layer, as well as one with this cooperating tow contact (88 and 248, respectively). Cathode atomizer according to claim 7, characterized in that the metal ring is formed as a concentric contact ring (116) arranged on the end surface of the drum anode (58). Cathode atomizer according to claim 7 or 8, characterized in that the metal ring (116) and the associated contacts (88) are located within the container (20) when the closure (28) is in its closing position. A cathode atomizer according to claim 7, characterized in that the towing ring (244) and the associated contacts (248) are arranged outside the container (210) and also in the open position of the closure (212) forms an interconnected electrical connection. Cathode sputtering apparatus according to claims 1-10, characterized in that the drum anode (58 and 236, respectively)