Filters for plasma plumes

Abstract

To provide a filter for filtering particles from a plasma plume.SOLUTION: A filter includes a housing 2, at least one primary blade and an exhaust passage 5. The housing includes two passage openings 14 forming a passage for passing at least a part of a plasma plume through the housing. The primary blade parallel to the center line of the passage and arranged at a distance separated from a rotation axis 16 separated from the center line of the passage can rotate around the rotation axis and has a contact surface facing the rotational direction for contacting the plasma plume. The exhaust passage is connected to an exhaust port arranged in the wall part of the housing, and a line extended to be orthogonal to both the center line 15 of the passage and a line 22 extended from the rotation axis and passing the center line of the passage and the orbit of the primary blade in the radial direction extends through the exhaust port.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a filter for filtering particles from a plasma plume.

[0002] The filter according to the present invention comprises: a housing and at least one primary blade; the housing has two passage openings disposed in a wall of the housing and forming a passage for passing at least a portion of the plasma plume through the housing; the passageway extends from one side of the housing to an opposite side of the housing; the at least one primary blade is disposed at a distance from an axis of rotation parallel to and spaced apart from a centerline of the passageway and rotatable about the axis of rotation; the trajectory of the at least one primary blade intersects the passageway; The at least one primary blade has a rotationally oriented contact surface for contacting the plasma plume. [Background technology]

[0003] Such filters are known, for example, from EP 2 410 074. When a plasma plume is generated by directing a laser pulse at a target material, a plasma of the target material leaves the surface of the target. Since a large amount of energy is input into the target material, a large amount of heat is generated locally. The heat generates particles that detach from the target material. Such unwanted particles follow the plasma plume and deposit on the substrate if no filtering is applied. As a result, the layer obtained on the substrate has a suboptimal quality. It is therefore desirable to filter the unwanted particles from the plasma plume so that only the plasma deposits on the substrate.

[0004] EP 2410074 discloses a filter for filtering particles from a plasma plume, comprising a cage-like housing. The housing has a closed top surface and a closed bottom surface spaced from the top surface by struts arranged around the periphery, resulting in open sides. Both the top and bottom surfaces have passages forming a passage for the passage of at least a portion of the plasma plume. A rotatable disk of rotatable vanes is arranged inside the housing. The vanes rotate simultaneously with the generation of the plasma plume, typically by pulsating a laser onto a target material. The rotatable disk of vanes sweeps the trailing edge of the plasma plume as it passes through the passage.

[0005] In EP 2410074 it is suggested that a rotatable disk or vane captures the unwanted particles in the plasma plume. This may be partially correct. However, the applicant has found that in order to optimize such a filtering device it is better to consider the unwanted particles as essentially behaving like marbles and to simply bounce them off the rotatable disk or vane and disperse them in space. In the filter described in EP 2410074 a housing with an open structure is used so that the unwanted particles are simply bounced off the outside of the filter housing, where a substrate is typically placed and on which the unwanted particles are deposited as before.

[0006] If the housing described in EP 2 410 074 is simply closed, the particles will bounce off the rotating disk or vanes, some of which will be carried along with the new plasma plume as it passes through the passage and reach the substrate, thus degrading the filtering properties. Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to reduce or even eliminate the aforementioned disadvantages and to provide a filter with improved filtering of particles from a plasma plume. [Means for solving the problem]

[0008] This object is achieved by the invention with a filter as described above, characterized by an outlet passage leading to an outlet arranged in the wall of the housing, through which a centerline of the passage and a line extending from the axis of rotation and perpendicular to both the centerline of the passage and to a radial line through the orbit of the at least one primary blade extend.

[0009] The filter according to the invention is provided with an exhaust passage along which the particles can be exhausted, and the contact surface of the at least one primary blade more reliably directs the particles towards the exhaust passage and the outlet of the housing as the primary blade passes through the cloud of particles trailing the plasma plume.

[0010] In a preferred embodiment of the filter according to the invention, the cord lines of the radial cross section of the contact surface make an angle with the axis of rotation greater than 0°, preferably greater than 15°. The cord lines are arranged such that the contact surface trails more particles closer to the source of the plasma plume than further away from the source, so that the fastest particles are captured by the part of the contact surface farther from the source, while slower or lagging particles in the plasma plume are more likely to be captured by the more trailing end of the contact surface.

[0011] In a further preferred embodiment of the filter according to the invention, the cord lines in the axial cross section of the contact surface make an angle greater than 0°, preferably greater than 15°, with a radial line extending from the axis of rotation through the inner edge of the axial cross section of the contact surface.

[0012] The angle relative to the radial line allows the particles to be directed towards the outlet. More preferably, the angle of the chord line of the axial cross section of the contact surface varies along the radial direction. When the plasma plume is generated at the target surface, the plasma and unwanted particles will leave in all directions so that the expanding plasma plume grows. The varying angle better allows for different directions of the particles.

[0013] In a further preferred embodiment of the filter according to the invention, the contact surface is a concave surface facing in the direction of rotation of the at least one primary blade.

[0014] If only flat surfaces were used on the blades, the particles would be further dispersed by the expanding plasma plume when they impacted the flat surfaces. The concave surface allows for a more focused direction of the particles and allows them to be expelled along the exhaust path. To this end, the concave surface has a direction that changes both radially and axially.

[0015] Generally, when angles greater than 0° are defined, such angles are considered to be within the range of 0° and 180°, while angles less than 0° are considered to be within the range of 0° and -180°. Thus, for example, an angle of -5° should not be considered as an angle greater than 0°, as adding 360° makes it equal to 355°.

[0016] It will be apparent to one skilled in the art that the shape of the concave surface will depend on process parameters such as the velocity of the plasma plume, the particles trailing the plasma plume, and the rotational speed of the blades.

[0017] A preferred embodiment of the filter according to the invention further comprises a disk rotatably arranged in the housing, the axis of rotation of the disk being coincident with the axis of rotation of the at least one primary blade, the at least one passage opening being arranged in the disk at a distance from the axis of rotation corresponding to the distance from the axis of rotation to the centerline of the passage, the at least one primary blade being arranged in an upper part of the disk adjacent to the at least one passage opening of the disk and following the at least one passage opening of the disk when seen in the direction of rotation of the disk.

[0018] The rotating disk provides a shutter for the passageway so that after the passage of the plasma plume the passageway is closed and particles that need to be filtered from the plasma plume can be swept towards the exhaust by the at least one primary blade.

[0019] In another embodiment of the filter according to the invention, the axis of rotation of the disk may be parallel to and spaced apart from the axis of rotation of at least one primary blade, provided that there is an overlap between the primary blade and the passage opening of the disk when viewed in the direction of the axis of rotation.

[0020] In a further preferred embodiment of the filter according to the invention, a cylindrical wall is arranged on the disk concentrically with the axis of rotation, at least one primary blade being connected to the outside of the cylindrical wall.

[0021] The cylindrical wall provides a radially inner boundary and the housing provides a radially outer boundary so that the particles are more confined after the passage is closed. The cylindrical wall and the housing wall can also help redirect the particles towards the outlet if they are bounced off the primary blade in the wrong direction.

[0022] Yet another embodiment of the filter according to the present invention further comprises a secondary blade rotatable about the axis of rotation and positioned to follow each of the at least one primary blade.

[0023] By placing a secondary blade behind each primary blade, particles that are not captured by the primary blades can also be captured by the secondary blades. This is particularly relevant for particles that are relatively slow or delayed with respect to the generation of the plasma and follow the plasma plume a relatively large distance. These particles have not yet reached the passageway when the primary blade passes through it. Thus, these particles enter the passageway behind the primary blade but before the secondary blade. The secondary blades deflect the slow or delayed particles towards the exhaust.

[0024] Preferably, the angle between the longitudinal axis of the at least one primary blade and a radial line extending from the axis of rotation to the base end of the at least one primary blade is less than the angle between the longitudinal axis of each secondary blade trailing the at least one primary blade and a radial line extending from the axis of rotation to the base end of the secondary blade.

[0025] The secondary blade is located immediately behind the primary blade and repels particles that are substantially slower than those repelled by the primary blade, so the angle of the secondary blade typically needs to be different to direct the slower particles towards the exhaust.

[0026] In yet another embodiment of the filter according to the invention, a plurality of auxiliary blades are arranged at a distance from the axis of rotation and rotatable about said axis of rotation, the plurality of auxiliary blades being distributed at a distance from the at least one primary blade along the trajectory.

[0027] A fan is provided within the housing by providing a number of auxiliary blades, the fan urging the remaining particles towards the exhaust passage.

[0028] A preferred embodiment of the filter according to the present invention further comprises an auxiliary discharge passage leading to an auxiliary discharge port arranged in the wall of the housing, and suction means for generating a pressure difference between the rotating shaft and the auxiliary discharge passage.

[0029] By creating a pressure difference between the axis of rotation, i.e. the center of the housing, and the auxiliary discharge, a flow is induced towards the discharge, which is favourable for maintaining pressure within the housing. The flow can be designed by providing inlets radially inside the blades. [Brief description of the drawings]

[0030] These and other features of the present invention will be explained in conjunction with the accompanying drawings.

[0031] [Figure 1] FIG. 1 is a schematic perspective view of an embodiment of a filter according to the present invention, showing the filter disposed in a PLD device. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a perspective view of a vaned disk in the filter of FIG. [Figure 4] FIG. 4 is a cross-sectional plan view of a filter according to the present invention, the filter being in a first state. [Diagram 5] FIG. 5 is a cross-sectional plan view of a filter according to the present invention, the filter being in a second position. [Figure 6A] FIG. 6A is an enlarged axial plan view of the primary blade having the concave surface shown in FIG. [Figure 6B] FIG. 6B is an enlarged radial cross-sectional view of the primary blade having a concave surface shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Fig. 1 is a schematic diagram of a first embodiment of a filter according to the present invention. Filter 1 includes a housing 2 having a passage opening 3 provided in an upper portion and a passage opening 4 (see Fig. 2) provided in a lower portion. Housing 2 is provided with a discharge passage 5 and an auxiliary discharge passage 6.

[0033] A target material 7 is disposed above the passage opening 3 of the filter 1. When the target material 7 is irradiated with a pulsed laser beam 8, a plasma plume 9 is generated. This plasma plume 9 enters through the passage opening 3, where unwanted particles are filtered out. As a result, the filtered plasma plume 10 leaves the filter 1 through the passage opening 4. The filtered plasma plume 10 is then deposited on a substrate 11.

[0034] As shown in Figure 2, a disk 12 is rotatably disposed within the housing 2 of the filter 1. A primary blade 13 having a concave surface is provided on the upper portion of the disk 12 adjacent to a passage opening 14. The passage opening 14 allows the plasma plume 9 to pass when aligned with the passage openings 3, 4 of the housing 2 to form a passageway having a centerline 15.

[0035] As the plasma plume 9 passes through the formed passageway, the primary blade 13 having a concave surface passes through the last part of the plasma plume 9 and deflects unwanted particles in the direction D towards the exhaust outlet and the exhaust passage 5 leading to the exhaust outlet.

[0036] 3 is a perspective view of a disk 12 rotatably arranged around a rotation axis 16 in the housing 2 of the filter 1. The disk 12 is provided with two passage openings 14 arranged opposite each other. A primary blade 13 having a concave surface trails each passage opening 14. A secondary blade 17 is arranged immediately behind each primary blade 13 to deflect particles towards the discharge channel 5 that are too slow to collide with the primary blades 13. Furthermore, a number of auxiliary blades 18 are arranged on the top of the disk 12.

[0037] Radially inwardly disposed from the primary blade 13, secondary blade 17 and auxiliary blade 18 is a cylindrical wall 19. The cylindrical wall 19, together with the housing 2, provides a more restricted space for the unwanted particles of the plasma plume 9.

[0038] 4 is a plan cross-sectional view of the filter 1 of the present invention. The housing 2 has an outlet 20 to which the outlet passage 5 is connected. The outlet 20 is disposed on a line 21 that extends perpendicular to both the center line 15 of the passage and a radial line 22 that extends from the axis of rotation 16 and passes through the center line 15 of the passage.

[0039] The housing 2 also has an auxiliary discharge port 23 to which the auxiliary discharge passage 6 is connected. The auxiliary discharge port 23 is disposed on a line 24 that extends perpendicular to both the center line 15 of the passage and a radial line 22 that extends from the rotation axis 16 and passes through the center line 15 of the passage.

[0040] Figure 5 is again a plan cross-sectional view of the filter 1 of the present invention. From this figure it is clear that a radial line 25 extending from the axis of rotation 16 to the proximal end of the primary blade 13 makes an angle α1 with a longitudinal axis 26 of the primary blade 13. A radial line 27 extending from the axis of rotation 16 to the proximal end of the secondary blade 17 makes an angle α2 with a longitudinal axis 28 of the secondary blade 17. A radial line 29 extending from the axis of rotation 16 to the proximal end of the auxiliary blade 18 makes an angle α2 with a longitudinal axis 28 of the auxiliary blade 18. 50 It makes an angle α3 with

[0041] As already mentioned above, the primary blade 13 bundles particles from the plasma plume 9 that strike the primary blade 13 towards the exhaust port 20 and the exhaust passage 5. 51 Furthermore, a pressure difference is generated between the center of the filter 1 around the rotation axis 16 and the auxiliary discharge passage 6. The pressure difference generates an air flow L that flows from the center toward the outside of the housing 2 in order to maintain the pressure inside the housing.

[0042] Figures 6A and 6B are an enlarged axial plan view and an enlarged radial cross-sectional view of the primary blade 13 having the concave surface shown in Figure 5. The concave surface 13 is curved from the lower edge 30 to the upper edge 31 of the concave surface 13 and is also curved in the radial direction.

[0043] The cord line 32 of the lower edge 30 makes an angle α1 with a radial line 33 that intersects with the innermost edge of the cord line 32. The cord line 35 of the upper edge 31 makes an angle β2 with a radial line 34 that intersects with the innermost edge of the cord line 35. Both angles α1 and β2 are greater than 0°, and preferably greater than 15°.

[0044] 6B is a cross-sectional view of the concave surface 13 seen from the radial direction. The cord line 36 makes an angle β3 with the axis of rotation 16. Also, this angle β3 is greater than 0°, preferably greater than 15°.

Claims

1. 1. A filter for filtering particles from a plasma plume, comprising: The filter comprises a housing and at least one primary blade; the housing has two passage openings disposed in a wall of the housing and forming a passage for passing at least a portion of the plasma plume through the housing; the passageway extends from one side of the housing to an opposite side of the housing; the at least one primary blade is spaced apart from an axis of rotation parallel to and spaced apart from a centerline of the passageway and rotatable about the axis of rotation; the trajectory of the at least one primary blade intersects the passageway; the at least one primary blade has a rotationally oriented contact surface for contacting the plasma plume; a discharge passage is provided which leads to a discharge port disposed in a wall of the housing; A filter, wherein a line extending from the axis of rotation and perpendicular to both the centerline of the passageway and a radial line through an orbit of the at least one primary blade extends through the outlet.

2. 2. The filter of claim 1, wherein a cord line in a radial cross section of the contact surface forms an angle greater than 0[deg.] with respect to the axis of rotation.

3. 3. A filter as claimed in claim 1 or claim 2, wherein a cord line in an axial cross section of the contact surface forms an angle of greater than 0° with a radial line extending from the axis of rotation through an inner edge of the axial cross section of the contact surface.

4. The filter of any one of claims 1 to 3, wherein the contact surface is a concave surface facing in the direction of rotation of the at least one primary blade.

5. The rotation axis is the rotation axis of the at least one primary blade, a disk rotatably disposed within the housing; the axis of rotation of the disk coincides with the axis of rotation of the at least one primary blade; at least one passageway is disposed in the disk at a distance from the axis of rotation of the disk corresponding to a distance from a centerline of the passageway to the axis of rotation of the at least one primary blade; the at least one primary blade is disposed at an upper portion of the disk adjacent to the at least one passage opening of the disk and following the at least one passage opening of the disk when viewed in the direction of rotation of the disk; A filter according to any one of claims 1 to 4.

6. A cylindrical wall is disposed on the disk concentrically with the axis of rotation; the at least one primary blade is connected to an exterior of the cylindrical wall; 6. The filter of claim 5.

7. A filter according to any preceding claim, further comprising a secondary blade arranged to be rotatable about the axis of rotation.

8. 8. The filter of claim 7, wherein an angle between a longitudinal axis of the at least one primary blade and a radial line extending from the axis of rotation to a proximal end of the at least one primary blade is less than an angle between a longitudinal axis of the secondary blade trailing each of the at least one primary blade and a radial line extending from the axis of rotation to a proximal end of the secondary blade.

9. A plurality of auxiliary blades are disposed at a distance from the rotation axis and rotatably about the rotation axis; the plurality of auxiliary blades are distributed along the trajectory at a distance from the at least one primary blade; A filter according to any one of the preceding claims.

10. an auxiliary exhaust passage leading to an auxiliary exhaust port disposed in a wall of the housing; a suction means for generating a pressure difference between the rotating shaft and the auxiliary discharge passage; The filter of claim 9 further comprising:

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