Shutter system for tightly shielding a coating source and corresponding method - Patents.com

Abstract

The present invention discloses a shutter system for shielding a coating source in a vacuum device, the shutter being configured to be slidable in front of the coating source, as well as a method implemented by the shutter system according to the invention. The problem of the present invention to provide an apparatus for a shutter system, which allows optimal shielding of the coating source, and thus completely prevents cross-contamination and undesired coating of the substrate to be coated, is solved by a shutter system, in which the shutter can be positioned to cover the coating source by means of a pivoting movement and / or a swiveling movement and / or a folding / tilting movement, and the shutter is configured to perform an additional relative movement with respect to the coating source and / or the coating source is configured to perform an additional relative movement with respect to the shutter, in which case the shutter covers the coating source in a tight seal.

Description

[Technical field]

[0001] The present invention relates to a shutter system comprising a shutter for shielding a coating source in a vacuum device, the shutter being configured to be slidable in front of the coating source.

[0002] The invention also relates to a method implemented by a shutter system according to the invention.

[0003] Sputtering is a coating technique from the group of PVD (physical vapour deposition) methods. Sputtering, also called cathodic scattering, is a physical process in which atoms are ejected from a solid, the so-called target, into the gas phase by bombardment with energetic (noble gas) ions. Depending on the material used and the envisaged film properties and deposition rate, different sputtering techniques are used.

[0004] That is, in the field of coating technology, sputtering is used to scatter materials, which are then deposited on a substrate to form a solid film. When coating a substrate with various materials, especially when sputtering, a shutter system is used to obtain a desired film thickness, which allows to control the flow rate of material to the substrate to be coated and to protect the target from inappropriate coating.

[0005] Sputtering is carried out under vacuum conditions in a coating apparatus. Depending on the sputtering mode used (DC sputtering, radio frequency sputtering, magnetron sputtering, ion beam sputtering, reactive sputtering, etc.), a voltage is applied between the two electrodes and a working gas is introduced into the gas chamber. A plasma is formed in the gas chamber by bombardment ionization of atoms of the working gas used, for example argon. The target usually forms the negative pole, the treatment chamber or the substrate to be coated usually forms the positively charged electrode. In the case of magnetron sputtering, an additional magnetic field is arranged behind the cathode plate. In the case of reactive sputtering, one or more reactive gases are added to the inert working gas (argon). The gas reacts with the scattered film atoms at the target or substrate in the vacuum chamber to form new material. In the case of ion beam sputtering, a beam of noble gas ions (argon, krypton, xenon) is guided from an ion source towards the target, where scattering is caused by the incident ion beam.

[0006] For a stable sputtering process, the coating device is switched on, i.e., a voltage is applied to the electrodes, the plasma is ignited, and the desired operating power for a stable process is adjusted and started. Only then is the shutter opened, which starts the coating of the substrate. The coating source is first shielded by the shutter. To ensure the ignition of the plasma, a gap of several millimeters must exist between the coating source and the shutter. Generally, a metal sheet as the shutter is laterally pivoted in front of the coating source, so that material cannot reach the substrate to be coated in an inconvenient manner from the coating source.

[0007] When the distance of the metal sheet to the coating source is minimal and the coating source is thus optimally shielded from the substrate, undesired material flows onto the substrate and into the surroundings of the coating source, so-called cross-contamination, are most effectively prevented.

[0008] In particular, if several coating sources are arranged in a coating or processing chamber, the inability to completely close the coating sources can result in mutual coating of the coating sources (targets) due to cross-contamination, which often requires the contaminated targets to be removed again by sputtering, also called removal sputtering, before the actual coating process of the substrate, in order to maintain and guarantee the quality of the coating material. This reduces the quality of the coating and the utilization rate of the materials as well as the productivity of the coating device.

[0009] Conventionally used shutter plates are slid or pivoted in front of the coating source with a distance of about 1-4 mm. This distance, however, cannot guarantee a completely closed shielding of the coating source. However, this distance is necessary for the sputtering of the coating source. In practical configurations, smaller, i.e. shorter, distances cannot be realized, since such distances generally cause friction between the shutter plate and the coating source. This friction effect causes a large number of undesirable particles that can lead to additional contamination of the coated substrate. This usually leads to a large loss of film quality, such as peeling of the film from the substrate or the production of defective products.

[0010] In the shutter mechanism known from WO 2021 / 091890, the shutter is connected to an actuator via a coupling system, so that the shutter can be moved in a combined motion from an open position to a closed position covering the coating source. In this case, the actuator only performs a linear motion along a translation axis, which is converted into a tilting motion via a grooved cam and then converted into a final linear motion again until the shutter surrounds the sputter source. The shutter first performs a linear motion along the translation axis of the actuator, then a pivoting motion, for example by 90° relative to the translation axis of the actuator, and finally a linear motion again along the translation axis of the actuator. The disadvantage is that these motions cannot be controlled separately and independently of one another, since on the one hand they are set by a grooved cam and on the other hand only a very limited fine adjustment of the shutter by the actuator is possible. Fixing the shutter in an intermediate position, for example for the sputtering process or pre-sputtering process, i.e. a few millimeters above the sputtering source, is not possible without additional technical equipment in the configuration described in WO 2021 / 091890 and can only be reproduced inaccurately, especially when pneumatic actuators are used.

[0011] Due to the fact that in the configuration described in WO 2021 / 091890 the axis of rotation of the shutter is not parallel to the longitudinal axis of the coating source, furthermore, during the opening and closing pivoting of the shutter, undesirable curvature of the gas plasma may occur, since the angle between the target surface and the shutter surface changes, which may additionally result in undesirable coating of the inside of the chamber or of the coating source itself.

[0012] It is also disadvantageous that in WO 2021 / 091890 the actuator is arranged in the vacuum chamber together with the grooved cam. The mechanical load of friction in the coupling system and the associated grooved cam can lead to undesirable wear in coating systems with high purity requirements. Maintenance and / or repair of the shutter control device is therefore also significantly more laborious, since maintenance and / or repair can only be carried out when the vacuum chamber is vented.

[0013] The object of the present invention is therefore to provide an arrangement for a shutter system, which allows optimal shielding of the coating source, so that cross-contamination and undesired coating on the substrate to be coated are completely prevented. A compact arrangement is desirable. The arrangement should be easy to maintain and require minimal effort in the event of repair measures. The shutter system should be precisely positionable in any required desired position.

[0014] This problem is solved by a shutter system according to claim 1. The shutter system consists of a shutter which shields a coating source in a vacuum device, the shutter being slidably configured in front of the coating source. According to the invention, the shutter can be positioned to cover the coating source by means of a rotating and / or pivoting and / or folding or tilting movement, and the shutter is configured to perform an additional relative movement with respect to the coating source and / or the coating source is configured to perform an additional relative movement with respect to the shutter, the shutter covering the coating source in a tight seal manner.

[0015] By tightly sealed, it is meant that the coating source is completely shielded from the rest of the processing chamber, thereby preventing any cross-contamination of the coating source and unwanted coating of the substrate being coated.

[0016] Advantageously, the shutter of the shutter system is not only pivoted or rotated or folded or tilted to cover the coating source based on a first degree of freedom, but the shutter or the coating source is also moved to seal against each other based on a second degree of freedom by a relative movement between the shutter and the coating source. The shutter performs a stroke movement in the direction of the coating source or the coating source performs a stroke movement in the direction of the shutter, so that the shutter and the coating source are positioned to seal against each other, i.e. completely closed. In this case, no particles are generated due to friction between the shutter plate and the coating source, such as in a pure pivoting of the shutter to cover the coating source. When the shutter is closed, there is no longer a gap, which prevents contamination of the target material due to the operation of another source in the same device.

[0017] The shutter can be positioned to cover the coating source, for example by a pivoting movement about an axis or by a pivoting movement by moving laterally towards the coating source. Only then does a relative movement or stroke movement take place between the shutter and the coating source. Both movements can be performed independently of one another, so that the shutter can be positioned in any required and desired position. No deflection of the gas plasma takes place by the movement of the shutter.

[0018] The proposed configuration allows for a significantly more compact arrangement of different coating sources in parallel and / or joint coating systems (e.g. sputter systems), since cross-contamination of the coating sources is prevented. Large overhangs of the shutter plate are no longer necessary.

[0019] In one configuration of the shutter system according to the invention, the relative movement between the shutter and the coating source is achieved via a bellows or ring seal and / or a sliding feedthrough. This reduces mechanical wear in the vacuum chamber to a minimum. No contamination due to wear or mechanical friction occurs.

[0020] The relative movement between the shutter and the coating source is achieved through a stroke motion performed by the shutter or by the coating source. The implementation of the relative movement by the shutter system is generally a relatively simple method since it can be realized mechanically. The implementation of the relative movement by the coating source is applied when one shield plate is shared by multiple coating sources (e.g., a shield plate with holes).

[0021] In one further 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 when starting the plasma ignition process in the sputtering process, the required gap between the coating source and the shutter can be adjusted and, in particular, in the actual coating process with multiple coating sources, each coating source can be shielded in an optimal manner. This is made possible by the movements of the shutter system, which can be controlled separately and carried out independently of one another.

[0022] In one further configuration of the shutter system according to the invention, the shielding is further significantly optimized if the shutter has curved edges, which allow the shutter to act as a sort of hood over the coating source, thus completely preventing cross-contamination.

[0023] In one alternative configuration of the shutter system according to the invention, the shutter and the coating source have a circular or elliptical or rectangular or polygonal shape, which allows the shutter to be adapted to the shape of the coating source to be coated, which allows the coating source to be optimally sealed. Due to the independently operable movement processes of the shutter (rotating and / or pivoting and / or folding or tilting movements, as well as additional relative movements), the shutter system according to the invention can be adapted very simply to any coating source as well.

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

[0025] In one alternative configuration of the shutter system according to the invention, the coating source is an electron beam evaporator.

[0026] In one alternative configuration of the shutter system according to the invention, the coating source is a boat type evaporator and / or a spiral type evaporator.

[0027] In one further configuration of the shutter system according to the invention, the coating source is an effusion cell. An effusion cell is a device for depositing coating source material in molecular beam epitaxy or for producing thin films in ultra-high and high vacuum. An effusion cell consists of a crucible (usually but not exclusively made of pyrolytic boron nitride (PBN)) in which the coating source material is embedded in solid form. The crucible is actively heated until the material evaporates, which is then lowered onto a substrate.

[0028] In other words, the shutter system according to the invention can be used with any coating source with a directed particle flow, making it possible in a simple and compact way to effectively prevent cross-contamination of the coating source and contamination of the substrate to be coated.

[0029] The problem is also solved by the method according to the invention as defined in the independent method claim 10. The method comprises the following steps, in which case the method is implemented by the shutter system according to the invention as defined in the apparatus claim. When the coating source is switched off, the shutter seals the coating source. Before switching on the coating source, a distance of 1-4 mm is adjusted between the shutter and the coating source by a relative movement of the shutter and the coating source relative to one another. As soon as stable process parameters have been adjusted, the shutter is opened by a rotating movement and / or a pivoting movement and / or a folding or tilting movement. The shutter remains open during the coating of the substrate, and only after the end of the coating of the substrate is the shutter pivoted or slid or folded / tilted over the coating source, which is again tightly sealed by a relative movement between the coating source and the shutter. By controlling the shutter system according to the invention, it is possible to hold the shutter in any required and desired position.

[0030] The present invention will be described in more detail below with reference to examples. [Brief description of the drawings]

[0031] [Figure 1a] 1 shows a cross-sectional view of a shutter system according to the invention with a coating source (sputter target), the shutters being located at different positions above the coating source. [Figure 1b]1 shows a cross-sectional view of a shutter system according to the invention with a coating source (sputter target), the shutters being located at different positions above the coating source. [Figure 1c] 1 shows a cross-sectional view of a shutter system according to the invention with a coating source (sputter target), the shutters being located at different positions above the coating source. [Figure 1d] 1 shows a cross-sectional view of a shutter system according to the invention with a coating source (sputter target), the shutters being located at different positions above the coating source. [Diagram 2] 1 shows a shutter system according to the invention with curved edges in a coating apparatus in a) tightly closed state and b) open state. FIG.

[0032] In FIG. 1 an embodiment of the shutter system according to the invention in an apparatus with a coating source 1 is shown with different positions of the shutter 2 during the coating process. When the coating source 1 is switched off, the shutter 2 seals it off. Before switching on the coating source 1, in particular when igniting a plasma during sputtering, a distance 7 of 1-4 mm is adjusted between the shutter 2 and the coating source 1 by a relative movement 4 between them. As soon as stable process parameters have been adjusted, the shutter 2 is fully opened by a rotating and / or pivoting and / or folding or tilting movement 5. The shutter 2 remains open during the substrate coating, and only after the end of the substrate coating is the shutter 2 again pivoted or slid or folded / tilted 5 over the coating source 1, and the coating source 1 is again tightly sealed by the relative movement 4 between the coating source 1 and the shutter 2. That is, the shutter 2 moves towards the coating source 1 via a linear stroke motion 4 , or the coating source 1 approaches the shutter 2 via a stroke motion 4 .

[0033] The advantage of the shutter system according to the invention is seen in that the shutter completely seals the coating source 1. No cross-contamination or unwanted parasitic coatings occur on the substrate. The controls of the shutter system are located outside the vacuum chamber, so wear from mechanical components inside the vacuum chamber is reduced to a minimum.

[0034] The shutter system according to the invention can be easily retrofitted to existing equipment so as to be able to take advantage of the above mentioned advantages.

[0035] In Fig. 2 a shutter system according to the invention is shown in a process chamber 9. In Fig. 2a the shutter 2 is positioned so as to tightly seal over the coating source 1. No coating material of the sputter target 10 can reach the process chamber 9 or the substrate 8. Due to the curved edge 3 of the shutter 2 a completely closed device with respect to the process chamber can be realised.

[0036] In Figure 2b the same apparatus as shown in Figure 2a is shown, but only the shutter has been rotated or pivoted or folded / tilted laterally so that a substrate 8 can now be coated. To open the shutter 2, either the shutter 2 or the coating source 1 performs a linear stroke movement 4, i.e. 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 laterally, rotated or pivoted 5. [Explanation of symbols]

[0037] 1. Coating Source 2 Shutter 3 Curved Edges 4. Relative movement between the shutter and the coating source, stroke motion 5 Rotating and / or swiveling and / or folding / tilting movements 6 Ring seal or sliding feedthrough or bellows 7. Distance between shutter and coating source 8 Substrate 9 Processing Room 10. Target

Claims

1. A shutter system comprising a shutter (2) for shielding a coating source (1) in a vacuum device, the shutter (2) being slidably formed in front of the coating source (1), 1. A shutter system, characterized in that the shutter (2) can be positioned to cover the coating source (1) by a rotating and / or pivoting and / or folding / tilting movement (5), and the shutter (2) is configured to perform an additional relative movement (4) with respect to the coating source (1) and / or the coating source (1) is configured to perform an additional relative movement (4) with respect to the shutter (2), the shutter (2) covering the coating source (1) in a tight seal.

2. 2. The shutter system according to claim 1, wherein the relative movement (4) between the shutter (2) and the coating source (1) is formed via a bellows or ring seal and / or a sliding feedthrough (6).

3. 3. The shutter system according to claim 1, further comprising an adjustable distance (7) between the coating source (1) and the shutter (2).

4. 2. The shutter system according to claim 1, wherein the shutter (2) has a curved edge (3).

5. 2. The shutter system of claim 1, wherein the shutter (2) and the coating source (1) have a circular or elliptical or rectangular or polygonal shape.

6. The shutter system of claim 1 , wherein the coating source (1) is a sputter target (10).

7. The shutter system of claim 1 , wherein the coating source (1) is an electron beam evaporator.

8. The shutter system according to claim 1 , wherein the coating source (1) is a boat type evaporator and / or a spiral type evaporator.

9. The shutter system of claim 1, wherein the coating source (1) is an effusion cell.

10. A method for shielding a coating source (1) by means of a shutter system according to claims 1 to 9, comprising the steps of: When the coating source (1) is switched off, a shutter (2) closes off the coating source (1), Before switching on the coating source (1), a distance (7) of 1 to 4 mm is adjusted between the shutter (2) and the coating source (1) by a relative movement (4) of the shutter (2) and / or the coating source (1), As soon as stable process parameters are adjusted, the shutter (2) is opened, The shutter (2) remains open during the coating of the substrate (8), After the coating of the substrate (8) is finished, the shutter (2) is pivoted, slid, folded or tilted (5) over the coating source (1), which is again tightly sealed by the relative movement (4) between the coating source (1) and the shutter (2). A method comprising:

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