Cathode sputtering apparatus

© Start of patent term: 1977 11 15 Longest possible duration:

© Issued on: 1978 07 25 © inventor:

© Dependency: '© Pamphlets considered to delineate the state of the art:

AT 344 501

- 2 No. 344501

General field of the invention is the coating of material by sputtering, ie

Glimmlichtentladungsbeschichtung and a device that is used in sputtering technology.

In particular, the invention is concerned with sputtering devices in which the anode is rotatable and a flexible carrier intended to receive the materials to be deposited, in particular photoelectric materials, is passed over the anode.

Devices of the subject type have a pressure vessel in which mounted at least one cathodic target and a rotatable anode is rotatably mounted, wherein a supply of flexible support, such as polyester film, is housed in the container and the container also receives a collecting device for the coated carrier. Suitable control and regulating devices for the operation of the device are also provided. The carrier is arranged to be passed over the anode, and a plasma generating the coating is produced in the container. The material making up the target is sputtered onto the anode, but it deposits as a coating on the support because it is carried by the surface of the anode.

Auxiliaries, feeders, and controllers are provided to bring the ionizing gas and components together and to monitor and control the loading of the chamber. Other auxiliary equipment is provided for the supply of electrical energy and for its monitoring and control and for monitoring and controlling its effects. Appropriate facilities are used to control and monitor the temperature, the strength of the deposits and many other parameters, including the drive of the carrier on his leadership and the monitoring and control of its tensile stress, etc. are used.

It has been found that among the depositions of certain materials, in particular photoelectric materials, on thin, flexible, transparent substrates, inter alia, the following deposition conditions are essential:

a) The anode should be rotatable.

b) The supplied energy is applied to the cathode, the anode and the shield in the container in an electrical circuit or network in which the cathode at the maximum negative voltage, the shield at ground potential and the anode also at a potential negative to ground but much lower than that of the cathode.

c) The surface of the anode should be monitored in temperature to avoid disproportionately high heat losses during the sputtering process.

Various other conditions and requirements of the devices make it very difficult to effectively meet the above conditions. This includes that the

d) the entire support structure of the device including the container walls must be kept at ground potential for practical and safety reasons,

e) the ends of the drum must be shielded to avoid excess deposits there and

f) it becomes necessary to insert the support and transport device of the device for the carrier into the chamber and to remove it from the chamber when the sputtering process is terminated.

The latter requirement is usually then strictly observed if larger quantities of coated carrier to be produced in the sputtering device, which of course takes up much space and becomes unwieldy. According to a proposed solution to this problem, the supporting structure for the carrier is mounted on a carriage with a majority of the control and measuring devices and the chamber with all its auxiliary devices mounted on a fixed support. In this case, the targets are located inside the container and also the high voltage terminals are associated with the chamber. This also applies to the associated control devices and

Instruments, but it is not taken into account that the anode must differ on one of the earth potential / the voltage must be maintained.

Accordingly, the invention relates to an apparatus for producing coatings, in particular of photoelectric material, on a flexible carrier by sputtering (glow-discharge coating), with a container in which at least one target is mounted and which has a closure, on which a rotatable drum anode is mounted , which in befindlichem in the closed position

- 3 No. 344501

Closure in a coating position relative to the target can be brought, wherein a transport device in the container leads the flexible carrier through the anode and through the resulting between the target and anode coating plasma, to generate it with closed shutter, grounded target and a grounded anode shielding a high-frequency electrical energy supplying Energy source via an electrical connection circuit with the target, the anode and the shield is connectable, wherein this device is characterized essentially by the fact that closure and container are formed metallic and held at the same potential as the shield, the drum anode has a body which is metallically connected to the shutter and has a metallic outer skin insulated from it and in the closure contacts isolated are mounted, which establish the electrical connection with the outer skin of the drum when the shutter is closed, wherein the drum anode is held at a voltage different from the shield and the target.

Further details and advantages of the subject invention will become apparent from the description of the drawings. For example, the subject of the invention is illustrated in the drawings. It shows: Fig.l sputtering device according to the invention in its closed position in side view, with various connections to external devices were fragmentarily drawn to indicate that such external devices are connected to the sputtering, Fig.2 in Fig.l corresponding representation, the sputtering device in the open state, 3 shows schematically a view according to the line III-III of Figure 2, wherein only the path of movement of the carrier has been shown, 5 is a partial section through the container along the line 5-5 of Figure 2, Figure 6 about the same area of ​​the container as in Figure 5 in the partial diagram, Fig. 7 shows a detailed section through the lower part of the drum anode of the device according to FIG. 1, from which it can be seen how the contact is produced, 8 in the block diagram, the electrical circuits of the sputtering device according to Fig.l and Figure 9 shows a partial section in a schematic representation by a modified apparatus.

In the following two practical embodiments of the subject invention will be described. One of them is suitable for commercial sputtering of coatings on relatively wide strips of polyester film and the other for low and slow production rates or experimental work and spatters coatings on narrow strips. The sizes of the two sputtering devices are considerably different. There are also differences in the length of the strips of material that can be coated without having to open the device. In one embodiment, the strip is on the order of about 50 cm and in the other version about 10 cm wide.

First of all, the larger and more complicated apparatus is dealt with in detail, although it operates according to principles and is also constructed according to principles which are also observed for the smaller apparatus.

The sputtering apparatus of Figs. 1-8 has been generally designated -10- and includes a fixed base or frame construction -12-- with support rails -14- at the top, a composite box -16- on rollers or wheels -18- engaging the rails -14-, a pressure vessel or pressure chamber -20- supported by the frame -12- by fixed supports -22- and various other parts and construction elements to be described. The box -16- carries on its left side a transport means -24-, which is supported on a front wall -28- of the box -16- connected projecting support frame -26-.

The wall -28- carries a circular sealing seat -30-. The conveyor -24- and the support frame -26- are dimensioned and arranged to lie in the cylinder defined by the projection of the seal seat. The pressure chamber or the pressure vessel -20- is closed on all sides except for its right end. In the area of ​​this end, a flange -32- is provided, which is intended for the tight engagement with the seal seat -30-. In the closed position of the device shown in Fig.l the box -16-- has been adjusted to the left, so that the transport device -24- inserted into the chamber and by the flange -32-, the seal seat -30- and by suitable Sealing and locking devices made certain termination connection hermetically.

-4Nr. 344501

In Fig.2, the apparatus is illustrated in its open position, in which the box -16 and the chamber or container -20- are separated so that the transport means -24- as well as the material carried by it and the interior of the chamber -20- are accessible.

The transport device shown does not show drive and control devices, since these are mounted in box -16- and for the most part at the rear of the wall -28-. The exact design of these parts can be subject to various variants, the details of which are not the subject of the invention, although it must be assumed that these devices are necessary for the operation of the device. Box 16 also includes appropriate apparatus and constructions for the overall operation of the apparatus, including speed controllers, drive means, pumps and conduits for a heat exchange fluid, a large number of temperature, pressure, current, voltage, etc. meters. On the outer wall of the box -16- many snaps, gauges, lamps, etc. were indicated.

The chamber or container -20- has gas connections -34 and 36-, an electrical control panel -38-, pipes and connections -40-, electrical connections -42-, pushbuttons, meters, etc., viewing windows -44- were also shown. All these parts should only show the overall impression. The device -10- requires appropriate monitoring and control known to those skilled in the art, the nature of the measurements, the operation and the control means will vary with the requirements of the device.

In principle, certain conditions for the operation of a sputtering device exist that must be adjusted, controlled and often stored. There are phenomena that need to be measured and monitored. The parameters to be observed are manifold. High-frequency electrical energy must be supplied to the targets, for which connection and control circuits, lines and often cooling devices are necessary. With regard to the latter, it should be noted that the target coolant must be introduced into the chamber because the targets are in the chamber or reservoir -20-. The coolant must be taken up and circulated. The container must be pumped out for operation so that vacuum pumps with associated regulation, control and measuring devices are required. Gases for the ionization and underground gas must be added, for which regulation, control and measuring devices as well as the ratio of the devices defining the gases become necessary again. It is believed that the devices performing these functions are present in the sputtering apparatus described, and it is therefore not necessary to present and describe these devices in greater detail.

The cantilevered support frame -26- has been illustrated only in Fig. 2, but it is of course, although not shown, in the devices according to the other drawings as a support for the conveyor -24- present. With him an outer plate -46- is present, which is connected via rods -48- with the wall -28- within the seal seat -30- in connection. All to be described rollers and the drum are rotatable, such as self-propelled or running, between the plate -46- and the wall -28- arranged.

In Figs. 3 and 4 the transport means -24- is shown but with the supports and mounting parts and the drive, coupling and braking means omitted which can be used with it and, as explained, in the box -16- can be accommodated. The support -50-- to be coated was displayed transparently. In the preferred use of the device, the support -50- forms the basis of an electrophotographic film having sputtered inorganic coatings. In this case, the carrier -50- is a synthetic resin film, eg polyester, which is about 0.12 to 0.25 mm thick. Several 100 m of this material can be mounted on a spool or wheel and fed into the device -10- where they are coated over their entire length. Such a coil has been shown and forms the carrier within the device. It is mounted on a shaft 54, preferably driven by a drive motor, but undergoes control by a voltage clutch receiving feedback information from speed measuring devices and controllers included in box -16-.

The carrier strip -50- travels over a follower roller -56- which leads it onto a drum -58- which forms the anode of the sputtering device -10-. From Figure 8 it can be seen that the carrier -50- is guided around the likewise rotating, normally revolving drum -58- while approaching the targets -60 and 62-, which, as will be described, at the bottom of the container

- 5 No. 344501 are arranged, and then moves up to another idler pulley -64-, from which it is guided to the take-up roller -66-, which is driven by suitable drive motors from the inside of the box -16--. Since the diameter of the carrier roll on the supply spool -52- or on the take-up spool -66- change in the opposite direction during the sputtering process and on the other hand

Adjustment speed of the carrier -50- must be uniform relative to the targets, it is necessary to precisely regulate this speed and provide suitable variable drives for the carrier.

Targets -60 and 62- are illustrated in FIGS. 5, 6 and 8. The chamber or container -20- has the shape of a cylindrical shell -68- with an end bell -70-, which connects to the line -36-. All these parts of the chamber or container are formed of stainless steel and are kept at ground potential for safety reasons. The manufacture of the container from this material is relatively simple compared to manufacture from glass or other insulating material. The targets -60 and 62- are mounted in target carriers -72 and 74-- which have metal shields -76- which are mounted to the bottom of the shell by means of the clamps -78-- and through which through the Walls of the shields -76- circulating coolant to be cooled. The lines and connections for the coolant are led through housing -80- through the shell -68-, which housing also allow the passage of the electrical connection elements, which serve to connect the targets to the power source. The positions of the targets relative to the drum -58- are adjustable with the consumption of the targets. This setting can be made via adjusting devices in the housings -80- or by means of the clamps -78-.

Each target 62 consists of a plurality of plates or plates, best seen in FIG. 6, cemented on a suitable metal sub-base, typically stainless steel. The facing the drum surfaces of the target plates may be flat or curved in the arc. They are generally arranged to define a cylindrical surface which, when the apparatus is closed, is coaxial with the drum axis when the drum is placed adjacent to the targets. Each target -60 and 62- is spaced from its shield -76- so as to form an enclosed gap. With the help of the tubes -84-- underground gas can be introduced into the cavity behind each target so that it passes through the wall of the shell -68- and exits the gaps around the targets and rinses their surface. Preferably, the

Target plates formed as sintered parts from the material to be sputtered.

Arranged between the target components is a stator -86- carrying one or more brush or sliding contacts -88-. These lead to a part of the electrical supply circuit and are connected for this purpose with in a manner to be described by the shell -68-- led leads. Preferably, these contacts are to be mounted with elastic support springs, which, as shown in Figures 2 and 7, they push to the right. They must be isolated from the shell as well as the targets -60 and 62-. The construction details of the drum -58- are initially skipped to describe the operation of the energy supply used in the device -10-. For the explanation of the supply circuit, reference is made to FIG. The construction of the drum -58- can be better explained by understanding the supply circuit.

According to Figure 8, the power supply of the device is shown in the block diagram. On the left in block -90- a high voltage source is illustrated. This high voltage source -90- is connected to the device -10- via a network -92- which has two lines -94 and 96- for the output. The highest voltage, for example of the order of 3000 V and a frequency of 13.56 MHz, appears on the line -94- and is applied to the targets -60 and 62- where it appears as a voltage to ground. The line -96- is at ground potential. The total shielding of the device -10- (indicated here only by the -58 drum, shields -76 and drum shields) is at ground potential, but the drum itself is not. Thus, the output of the terminal network -92- is supplied to a voltage divider, which in this simple example two lines -94 and 96- connecting impedances Z₁ and Z₂ having.

Capacitors may be provided in the practice of practice, and a portion of the voltage divider may account for parasitic capacitance paths which may have some significance at that frequency. The leads may be high frequency fittings, coaxial cables, shielded wires, etc.

- 6 No. 344501

The voltage is adjusted according to the reactances of the two impedances and Z₂ divided. The drum -58- is connected via a line -98- to the tap -100- between the two impedances and Z₂ connected. To allow rotation of the drum -58-, use is made of the previously described contacts -88- by means of which the drum can be held at a voltage which does not correspond to the earth potential. The electronic effect in the sputtering process in the device -10- is that of a diode, so that an effective rectification takes place. The cathodes are the targets -60 and 62- which are kept at a very high negative voltage, in the example -3000V. This voltage indication below the ground potential means that the highest positive voltage in the system is zero V.

Normally, the anode is at ground potential and the carrier is placed on top of it. In the current embodiment, only the shield is at ground potential. The drum -58- represents the anode and is also maintained at a voltage below ground, but not to the same extent as targets -60 and 62-. In the practical example, the voltage on the drum was kept at a value of about 50 V or below below ground potential. This was done by a corresponding measurement and design of the voltage divider Z_t and Z₂ and other parts of the circle. The specialist in high frequency understands the nature and nature of the connection circuit.

The drum -58- should be able to rotate, be made of metal, so that it can be easily made and has the necessary strength for the needs of the sputtering device. It is necessary to mount the drum using mechanically durable bearings, shafts and supports, and further it is necessary to maintain at least the outer skin of the drum at a voltage deviating from the environment. Further requirements of the drum are that its outer skin should be suitable for temperature control by means of heat exchange fluids. In a practical realization of the invention, it has been found necessary to heat the outer skin of the drum by means of oil to keep it at a temperature of about 150 ° C.

All these requirements are met in the use of the drum of Figure 7. The body of the drum -58- consists of an inner metal cylinder -102- with welded Endflansehen or rings -104-. The metal end caps or disks -106- are connected to the cylinder -102- via the circumferential bolts -108-. An outer coaxial metal cylinder -110- forms the peripheral skin of the drum -58- and is welded to a coaxially telescopically arranged metal cylinder -112- smaller diameter, so that between them a chamber -114- arises. Cylinders -110 and 112- are connected by metal end-rings -116- at both ends, and the left metallic end remains exposed as shown.

The chamber -114- takes the heat exchange fluid -118- either in the filled state, so that the entire chamber is filled by this liquid or in line spirals inside the chamber (not shown). The liquid is connected via suitable connecting lines or connections -120- with the hollow shaft -122-, so that the connection is made to a supply. Corresponding leads -120'- have been indicated. Since the liquid is normally oil or another insulating liquid, there are no problems with the application of insulating couplings for the compounds -120 or 120'-, so that the skin is removed from the rest of the drum. the shaft -122- etc. remains electrically isolated.

The rings -116- and the disks -106- are arranged at a radial distance, so that at each end of the drum -58- a radial gap or annular gap -124- remains free. A cylinder -126- of polytetrafluoroethylene or other stable insulating material is formed, for example, by machining and mounted between cylinders -102 and 112-. Its ends are worked to a smaller thickness than the rest of its body, so that shoulders -128 and 130- arise. The resulting axial ends -132- are brought to a thickness that corresponds to that of the annular gap -124-. The length of the cylinder -126- corresponds exactly to the total length of the drum -58-, so that the cylinder -126- terminates with the outer ends of the disks -106- and the rings -116-. This results in a composite cylinder part whose outer skin is -110- isolated from the rest of the drum -58-. The drum is held together by a plurality of screws which are guided by bushes or seals of the same insulating material and distributed circumferentially about the ends of the drum. The rifles -136- are in deep recesses

- 7 No. 344501-138-, which are drilled in the outer ends of the drum -58-, each recess extending in one piece through a -106, a -116 and axial end -132-. To this

Way, the clamped by the bushes -136- and screws -134- in the axial direction

Parts additionally locked against relative adjustments in the circumferential direction.

The ring -116- at the left end of the drum -58- is mounted so that, when the device is closed, the contacts -88- can engage and rub over it so that the electrical contact is made.

As shown, shields -140, 142, 144- are provided for the ends of the drum to prevent material from being deposited on other parts of the drum while the carrier -50- travels around the underside of the skin -110- and there is coated. The plasma accompanying the sputtering process was illustrated by -146-. The shield is supported by the wall 28 and the support frame 46, for example via connection clips -147- according to FIGS. 2, 3 and 4. FIG. From Figure 7, it should be apparent that the shields -140, 142 and 144- let the drum ends but allow the passage of the carrier strip -50- and leave open an opening which allows the contacts -88- to ring - 116 - to grind. These shields are at earth potential and do not touch the drum skin at any point.

An embodiment of the subject invention, which is particularly suitable for small projects, has been illustrated in Figure 9. The sputtering apparatus has a chamber -210- with a shutter -212-- which is adapted for engagement with a flange -214- of the chamber -210- and lockable in place. A package -216- between flanges -214 and 218- is sealed.

The cover carries a supply spool -220 and a take-up spool -222-- mounted on shafts -224 and 226--, respectively. The shafts are driven by motors -228 and 230-, respectively, which are controlled from the outside of the device.

The cover -212- carries a coupling -232-, on which the drum -236- is hung up. In this case, the drum is made of metal and is insulated in its entirety from the chamber -210- and the cover -212- by a suitable insulation in the coupling -232-. It is mounted on a shaft -238- guided by the clutch --232- and mounted on top of the cover -212-. A chain and chain carrier -242- make the coupling with the shaft -238-, without shorting the drum to ground. For this purpose suitable insulation is provided. A ring -244- on the shaft -238- is electrically connected to the drum -236- and insulated from all other parts of the device -200. The electrical connection -246- with the contacts -248- corresponds to the line -98- and the contacts -88- of Figure 8.

The drum is hollow and has a central hollow conduit -250-- such that coaxial chambers -252 and 254- are formed which connect to a pipe -256- leading inside the skin of the drum -236-. A heat exchange fluid may enter and circulate through chambers -252 and 254-. At the top of the illustration, one can see where appropriate couplings are mounted to allow rotation of the shaft -250- using rotary fluid couplings. This need not be explained in detail.

In this device 200- the target -260- is a simple disc of photoelectric material mounted in a holder 262-- which extends across the wall -210 of the chamber -210- with a radiofrequency AC voltage supplying supply unit -266- is connected. It is assumed that the supply device shown in FIG. 8 is also used in connection with the device 200.

In addition to the drum -236 of the tumble on the shaft -238- and the target -260- shieldings -268, 270 and 272-- held at ground potential are provided. In the same way as with the device -10-, plasma is generated for the sputtering process by the use of suitable high-frequency energy and a suitable background gas, which in the exemplary embodiment via a line -274- in the gap -276- between the skin -258- of the drum -236- and the top of the target is headed -260-.

- 8 No. 344501