Shutter system for gap-free shielding of a coating source, and associated method

Abstract

The invention discloses a shutter system consisting of a shutter for shielding a coating source in a vacuum system, wherein the shutter is configured such that it can be slid in front of the coating source; and a method which is carried out by means of the shutter system according to the invention. The problem of the invention of specifying an arrangement for a shutter system, by means of which the coating source can be optimally shielded, in order to completely prevent both cross-contaminations and undesired coatings on a substrate to be coated, is solved by a shutter system in which the shutter can be positioned above the coating source by means of a rotary and / or pivoting and / or folding / tilting movement, and the shutter is configured to carry out an additional relative movement with respect to the coating source, and / or the coating source is configured to carry out an additional relative movement with respect to the shutter, wherein the shutter covers the coating source in a sealing and gap-free manner.

Description

[0001] Shutter system for gap-free shielding of a coating source and associated method

[0002] The invention relates to a shutter system comprising a shutter for shielding a coating source in a vacuum system, wherein the shutter is designed to be pushed in front of the coating source.

[0003] The invention also relates to a method which is carried out by means of the shutter system according to the invention.

[0004] Sputtering is a coating technique from the group of PVD (physical vapor deposition) processes. Sputtering, also known as cathode sputtering, is a physical process in which atoms are released from a solid, the so-called target, by bombardment with high-energy (noble gas) ions and pass into the gas phase. Depending on the materials used, as well as the desired layer properties and deposition rates, various sputtering technologies are employed.

[0005] In the field of coating technology, sputtering is used to atomize a material, which then deposits on a substrate and forms a solid layer. To achieve a defined layer thickness when coating, especially when sputtering, various materials onto a substrate, shutter systems are used to control the material flow onto the substrates to be coated and to protect the target from foreign coating.

[0006] Sputtering takes place in a coating system under vacuum conditions. Depending on the sputtering variant used (DC sputtering, RF sputtering, magnetron sputtering, ion beam sputtering, reactive sputtering, etc.), a voltage is applied between two electrodes and a working gas is admitted into the gas space. Impact ionization of the atoms of the working gas used, e.g. argon, creates a plasma in the gas space. The target usually forms the negative electrode and a process chamber or the substrate to be coated usually forms the positively charged electrode. In magnetron sputtering, an additional magnetic field is arranged behind the cathode plate. In reactive sputtering, one or more reactive gases are added to the inert working gas (argon). The gases react with the sputtered layer atoms on the target in the vacuum chamber or on the substrate to form new materials.In ion beam sputtering, a beam of noble gas ions (argon, krypton, xenon) is directed from an ion source onto the target - atomization occurs due to the incoming ion beam.

[0007] To ensure a stable sputtering process, the coating system is switched on, i.e. the voltage is applied to the electrodes, the plasma is ignited, and the desired operating power is set and reached for a stable process. Only then is the shutter opened to begin coating the substrates. Beforehand, the coating source is shielded by a shutter. To ensure that the plasma is ignited, there must be a gap of a few millimeters between the coating source and the shutter. Typically, a metal sheet is swung sideways in front of the coating source as a shutter to prevent any material from the coating source from accidentally getting onto the substrates to be coated.An undesired material flow, so-called cross contamination, onto the substrates and the surroundings of the coating source is most effectively prevented if the distance between the sheet and the coating source is as small as possible and the coating source is thus optimally shielded from the substrates.

[0008] Particularly in arrangements of multiple coating sources within a coating or process chamber, mutual coating of the coating sources (targets) can occur due to cross-contamination if the coating sources cannot be completely sealed. This often makes it necessary to remove the contaminated targets by sputtering, also known as free sputtering, before the actual coating process of the substrates in order to maintain and guarantee the quality of the coating materials. This reduces both the coating quality and material utilization as well as the productivity of the coating arrangement.

[0009] To date, the shutter plates used have been pushed or pivoted in front of the coating source at a distance of around 1 to 4 mm. However, this distance cannot guarantee completely enclosed shielding of the coating source. This distance is necessary for sputtering in a coating source. Smaller, i.e. closer distances cannot be achieved in practice, as they usually lead to friction between the shutter plate and the coating source. This friction effect causes many unwanted particles, which can lead to additional contamination of the coated substrates. This usually leads to massive loss of quality of the layer, such as detachment of the layers from the substrate and even scrap.

[0010] From WO 2021 / 091890 A1 a shutter mechanism is known in which a shutter is connected to an actuator via a coupling system in such a way that the shutter can be moved in a compound movement from an open position to a closed position over a coating source. The actuator only carries out a linear movement along a translation axis, whereby a grooved curve converts a linear movement of the shutter into a tilting movement and then back into a final linear movement until the shutter encloses the sputter source. The shutter first carries out a linear movement along the translation axis of the actuator, then a rotational movement, e.g. by 90°, to the translation axis of the actuator and finally a linear movement again along the translation axis of the actuator.The disadvantage is that these movements cannot be controlled separately and independently of one another. Firstly, they are predetermined by the grooved curve, and secondly, fine adjustment of the shutter using the actuator is only possible to a very limited extent. Particularly when using a pneumatic actuator, keeping the shutter in an intermediate position, e.g., for initial or pre-sputtering processes, i.e., a few millimeters above the sputter source, according to the solution described in WO 2021 / 091890 A1, is not possible without additional technical devices and can only be reproduced with imprecise accuracy.

[0011] Due to the fact that in the solution described in WO 2021 / 091890 A1, the shutter's rotation axis is not parallel to the longitudinal axis of the coating source, a detrimental curvature of the gas plasma can occur during the opening and closing of the shutter, as the angle between the target and shutter surfaces changes. This can also result in undesirable coating of the chamber interior or the coating source itself.

[0012] Another disadvantage is that the actuator in WO 2021 / 091890 A1 is arranged with the grooved cam within the vacuum chamber. The mechanical stress on the coupling system and the associated friction in the grooved cam can lead to abrasion, which is undesirable in a coating system with high purity requirements. Maintenance and / or repair of the shutter control is also significantly more complex, as this can only be performed when the vacuum chamber is ventilated.

[0013] It is therefore an object of the invention to provide an arrangement for a shutter system by means of which the coating source can be optimally shielded in order to completely prevent both cross-contamination and unwanted coatings on a substrate to be coated. A compact arrangement should be aimed for. The arrangement should be low-maintenance and require little effort for repair measures. The shutter system should be able to be positioned precisely in any required and desired position.

[0014] The object is achieved by a shutter system according to the independent arrangement claim 1. The shutter system consists of a shutter for shielding a coating source in a vacuum system, wherein the shutter is designed to be pushed in front of the coating source. According to the invention, the shutter can be positioned above the coating source by means of a rotating and / or pivoting and / or folding or tilting movement and the shutter is designed to carry out an additional relative movement to the coating source and / or the coating source is designed to carry out an additional relative movement to the shutter, wherein the shutter covers the coating source in a sealing and gap-free manner.

[0015] A sealing and gap-free covering means the complete shielding of the coating source from the rest of the process chamber, so that any cross-contamination of the coating source as well as unwanted coatings on the substrate to be coated are prevented.

[0016] It is advantageous that the shutter of the shutter system is not only pivoted, rotated, folded or tilted over the coating source according to a first degree of freedom, but the shutter or the coating source are moved in a sealing manner relative to one another according to a second degree of freedom by a relative movement between the shutter and the coating source. Either the shutter executes a lifting movement in the direction of the coating source or the coating source executes a lifting movement in the direction of the shutter, so that the shutter and the coating source are positioned in a sealing manner, i.e. completely closed, on one another. This does not create particles due to friction between the shutter plate and the coating source, as occurs when the shutter is simply pivoted over the coating source.When the shutter is closed, there is no longer a gap, which prevents contamination of the target material by operating other sources in the same arrangement.

[0017] The shutter can be positioned above the coating source, for example, by rotating it around an axis or by pivoting it sideways toward the coating source. Only then does the relative movement or lifting movement between the shutter and the coating source occur. Both movements can be performed independently of each other, allowing the shutter to be positioned in any required or desired position. The gas plasma is not deflected by the shutter's movements.

[0018] The proposed solution enables a significantly more compact arrangement of different coating sources in a parallel and / or co-coating arrangement (e.g., sputtering arrangement), as cross-contamination of the coating sources is prevented. A large overhang of the shutter plates is no longer necessary.

[0019] In one embodiment of the shutter system according to the invention, the relative movement between the shutter and the coating source is achieved by means of bellows or ring seals and / or sliding bushings. This minimizes mechanical wear within the vacuum chamber. Contamination due to abrasion or mechanical friction does not occur.

[0020] The relative movement between the shutter and the coating source is achieved by means of a reciprocating motion, which is carried out either by the shutter or by the coating source. Implementing the relative movement via the shutter system is usually the simpler method due to its mechanical feasibility. Implementing the relative movement via the coating source is used when a single aperture is shared by multiple coating sources (e.g., pinhole apertures).

[0021] In another embodiment of the shutter system according to the invention, the distance between the coating source and the shutter is adjustable. This has the advantage that the necessary gap between the coating source and the shutter can be adjusted at the start of the process for igniting the plasma during the sputtering process, and during the actual coating process, especially with multiple coating sources, each coating source can be optimally shielded and sealed. This is made possible by the separately controllable and independently executable movements of the shutter system.

[0022] Shielding is further optimized if, in a further embodiment of the shutter system according to the invention, the shutter has a bent edge. Due to the bent edge, the shutter acts like a kind of hood over the coating source, so that cross-contamination can be completely prevented.

[0023] In a further embodiment of the shutter system according to the invention, the shutter and the coating source have a round, oval, rectangular, or polygonal shape. This allows the shutter to be adapted to the shape of the coating source to be covered in order to optimally seal it. Due to the independently executable movements (rotation and / or pivoting and / or folding or tilting movement, as well as the additional relative movement) of the shutter, the shutter system according to the invention can also be easily adapted to any coating source.

[0024] In one embodiment of the shutter system according to the invention, the coating source is a sputter target.

[0025] In another embodiment of the inventive

[0026] Shuttersystems the coating source is an electron beam evaporator.

[0027] In a further embodiment of the shutter system according to the invention, the coating source is a boat and / or reversible evaporator.

[0028] In a further embodiment of the shutter system according to the invention, the coating source is an effusion cell. An effusion cell is a device for evaporating the coating source materials in molecular beam epitaxy or in the production of thin films in ultra-high and high vacuum. It consists of a crucible (usually, but not exclusively, made of pyrolytic boron nitride (PBN)) in which the coating source material is stored in solid form. The crucible is actively heated until the material evaporates and is then deposited on the substrate.

[0029] Thus, the shutter system according to the invention can be used for any coating source with a directed particle stream. Effective prevention of cross-contamination of the coating source and contamination of a substrate to be coated is thus possible in a simple and compact manner.

[0030] The object is also achieved by a method according to the invention according to the independent method claim 10. The method comprises the following steps, wherein the method is carried out with the shutter system according to the invention according to the arrangement claims:

[0031] When the coating source is switched off, the shutter closes the coating source sealingly. Before the coating source is switched on, a distance of 1 to 4 mm is set between the shutter and the coating source by a relative movement of the shutter and the coating source. As soon as stable process parameters have been established, the shutter is opened by a rotating and / or pivoting and / or folding or tilting movement. The shutter remains open during substrate coating and only after substrate coating has been completed is the shutter pivoted or pushed or folded / tilted over the coating source and the coating source is closed again by a relative movement between the coating source and the shutter, sealingly and gap-free. The control of the shutter system according to the invention allows the shutter to be held in any required and desired position.

[0032] In the following, the invention will be explained in more detail using exemplary embodiments. The accompanying drawings show

[0033] Fig. 1: A cross-sectional view of a shutter system according to the invention with a coating source (a sputter target); the shutter is located in various positions above the coating source;

[0034] Fig. 2 Shutter system according to the invention with a cranked edge in a coating system a) with a closed, gap-free shutter, b) with an open shutter.

[0035] Figure 1 shows an embodiment of the shutter system according to the invention in an arrangement with a coating source 1 in different positions of the shutter 2 during a coating process. When the coating source 1 is switched off, the shutter 2 seals off the coating source 1. Before switching on the coating source 1, in particular when igniting the plasma during sputtering, a relative movement 4 of the shutter 2 and the coating source

[0036] 1, a distance 7 of 1 to 4 mm is set between the shutter 2 and the coating source 1. As soon as stable process parameters have been established, the shutter 2 is fully opened by a rotating and / or pivoting and / or folding or tilting movement 5. The shutter

[0037] 2 remains open during the substrate coating and only after the substrate coating has been completed is the shutter 2 pivoted or pushed or folded / tilted 5 over the coating source 1 and the coating source 1 is closed again in a sealing and gap-free manner by means of a relative movement 4 between the coating source 1 and the shutter 2. This means that either the shutter 2 moves towards the coating source 1 via a linear stroke movement 4 or the coating source 1 is moved towards the shutter 2 by a stroke movement 4.

[0038] The advantage of the shutter system according to the invention is that the shutter completely seals the coating sources 1. No cross-contamination or unwanted parasitic coatings occur on the substrate. The shutter system's control system is located outside the vacuum chamber, so that abrasion caused by mechanical components within the vacuum chamber is reduced to a minimum.

[0039] With the shutter system according to the invention, existing systems can be easily retrofitted in order to be able to take advantage of the aforementioned advantages.

[0040] Figure 2 shows the shutter system according to the invention in a

[0041] Process chamber 9. In Figure 2a, the shutter 2 is positioned sealingly and gap-free over the coating source 1. No coating material from the sputter target 10 can enter the process chamber 9 or onto the substrate 8. The bent edge 3 of the shutter 2 enables a gap-free arrangement that is completely sealed off from the process chamber.

[0042] Figure 2b shows the same arrangement as in Figure 2a, except that the shutter has been turned, pivoted, or folded / tilted to the side so that the substrate 8 can now be coated. To open the shutter 2, either the shutter 2 or the coating source 1 performs a linear lifting movement 4, i.e. either the shutter 2 moves away from the coating source 1 or the coating source 1 moves away from the shutter 2 and is then folded / tilted, turned, or pivoted 5 to the side.

[0043] List of reference symbols 1 Coating source

[0044] 2 shutters

[0045] 3 Cranked edge

[0046] 4 Relative movement between shutter and coating source, lifting movement 5 Rotating and / or panning and / or folding / tilting movement

[0047] 6 Ring seal or sliding bushing or bellows

[0048] 7 Distance between shutter and coating source

[0049] 8 Substrat

[0050] 9 Process chamber 10 Target

Claims

Claims: A shutter system comprising a shutter (2) for shielding a coating source (1) in a vacuum system, wherein the shutter (2) is designed to be slid in front of the coating source (1), characterized in that the shutter (2) can be positioned above the coating source (1) by means of a rotary and / or pivoting and / or folding / tilting movement (5), and the shutter (2) is designed to perform an additional relative movement (4) to the coating source (1), and / or the coating source (1) is designed to perform an additional relative movement (4) to the shutter (2), wherein the shutter (2) covers the coating source (1) in a sealing and gap-free manner. A shutter system according to claim 1, characterized in that the relative movement (4) between the shutter (2) and the coating source (1) is formed by means of bellows or ring seals and / or sliding feedthroughs (6).Shutter system according to claim 1 or 2, characterized in that a distance (7) between the coating source (1) and the shutter (2) is adjustable. Shutter system according to claim 1, characterized in that the shutter (2) has a... has a bent edge (3). Shutter system according to claim 1, characterized in that the shutter (2) and the coating source (1) have a round, oval, rectangular, or polygonal shape. Shutter system according to claim 1, characterized in that the coating source (1) is a sputter target (10). Shutter system according to claim 1, characterized in that the coating source (1) is an electron beam evaporator. Shutter system according to claim 1, characterized in that the coating source (1) is a boat and / or rotary evaporator. Shutter system according to claim 1, characterized in that the coating source (1) is an effusion cell. Method for shielding a coating source (1) with a shutter system according to claims 1 to 9, characterized in that - when the coating source (2) is switched off, the shutter (2) seals the coating source (1) in a sealing manner, - that before switching on the coating source (1) a distance (7) of 1 to 4 mm is set between the shutter (2) and the coating source (1) by a relative movement (4) of the shutter (2) and / or the coating source (1) to each other, - that as soon as stable process parameters have been established, the shutter (2) is opened, - that the shutter (2) during substrate coating (8) remains open, - that after completion of the substrate coating (8) the shutter (2) is pivoted or pushed or folded or tilted (5) over the coating source (1) and the coating source (1) is sealed again by means of a relative movement (4) between coating source (1) and shutter (2) in a gap-free manner.

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