Method for Pulsed Laser Deposition

Abstract

The invention relates to a method for pulsed laser deposition including the steps of: providing a target and a substrate facing the target; irradiating a spot on the target with a pulsed laser beam to generate a plasma plume of target material and depositing the plasma plume on the substrate; and smoothing the surface structure of the spot on the target prior to irradiating the spot with a pulsed laser beam.

Claims

1. A method for pulsed laser deposition, comprising: providing a target and a substrate facing the target; irradiating a spot on the target with a pulsed laser beam to generate a plasma plume of target material and depositing the plasma plume on the substrate; and smoothing a surface structure of the spot on the target prior to irradiating the spot with a pulsed laser beam.

2. The method according to claim 1, further comprising: moving the target with the smoothed spot under the pulsed laser beam for the smoothed spot to be irradiated.

3. The method according to claim 1, wherein the smoothing step comprises a heating step, wherein at least an upper layer of the surface structure of the spot is melted with an energy beam wherein energy of the energy beam is below a plasma generation threshold.

4. The method according to claim 3, wherein at least the upper layer is allowed to solidify before the spot is irradiated with the pulsed laser beam.

5. The method according to claim 3, wherein the smoothing step comprises a particle bombardment treatment of the surface structure of the spot on the target in order to remove adhering particles.

6. The method according to claim 5, wherein the particle bombardment treatment step and the heat treatment are executed one after the other.

7. The method according to claim 1, wherein after the smoothing step, the target is moved to position the spot of the target with the smoothed surface structure under the incident pulsed laser beam.

8. The method according to claim 1, wherein the target is moved and wherein a displacement speed of the target, the smoothing of the spot on the target, and the irradiating of the spot is controlled such that the smoothed spot of the target arrives at the moment the pulsed laser irradiates the target.

9. The method according to claim 1, wherein the smoothing step is repeated after one or more irradiating steps for the same spot on the target.

10. The method according to claim 3, wherein the energy beam comprises a laser beam.

11. The method according to claim 8, wherein moving the target comprises rotating or translating the target.

12. The method according to claim 2, wherein the smoothing step comprises a heating step, wherein at least an upper layer of the surface structure of the spot is melted with an energy beam wherein energy of the energy beam is below a plasma generation threshold.

13. The method according to claim 12, wherein at least the upper layer is allowed to solidify before the spot is irradiated with the pulsed laser beam.

14. The method according to claim 1, wherein the smoothing step comprises a particle bombardment treatment of the surface structure of the spot on the target in order to remove adhering particles.

15. The method according to claim 2, wherein the smoothing step comprises a particle bombardment treatment of the surface structure of the spot on the target in order to remove adhering particles.

16. The method according to claim 4, wherein the smoothing step comprises a particle bombardment treatment of the surface structure of the spot on the target in order to remove adhering particles.

17. The method according to claim 2, wherein after the smoothing step, the target is moved to position the spot of the target with the smoothed surface structure under the incident pulsed laser beam.

18. The method according to claim 5, wherein after the smoothing step, the target is moved to position the spot of the target with the smoothed surface structure under the incident pulsed laser beam.

19. The method according to claim 2, wherein the target is moved and wherein a displacement speed of the target, the smoothing of the spot on the target, and the irradiating of the spot is controlled such that the smoothed spot of the target arrives at the moment the pulsed laser irradiates the target.

20. The method according to claim 2, wherein the smoothing step is repeated after one or more irradiating steps for the same spot on the target.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] These and other features of the invention will be elucidated in conjunction with the accompanying drawings.

[0035] FIG. 1 shows a schematic view of an embodiment of the method according to the invention.

[0036] FIGS. 2A-2D show enlarged cross sectional views of the surface structure of the target in different stages of the method according to the invention.

DESCRIPTION OF THE INVENTION

[0037] FIG. 1 shows a disc of target material 1, which is rotated at a desired rotational speed. Above and partially overlapping, when seen in the direction of the rotation axis, is a substrate 2 arranged, which is also rotated, such that the full surface of the substrate can be provided with a layer of target material.

[0038] FIG. 1 shows the same spot 3 on the target 1 after different time intervals. The different time intervals of the same spot 3 have been indicated with the letters A-D.

[0039] The spot 3A has been ablated by a previous irradiation by a laser beam 4 and has a surface structure as depicted in FIG. 2A. The spot 3A has a surface structure with a number of cones 5, cracks 6 and adhered particles 7.

[0040] Due to the rotation of the target 1, the spot 3 is positioned underneath a particle bombardment device 8, such as an ion beam, electron beam or photon beam, which fires a plurality of particles onto the surface of the spot 3 to remove the particles 7.

[0041] As depicted in FIG. 2B, the spot 3 has been cleaned from the adhered particles 7, but still has the cones 5 and cracks 6.

[0042] By further rotation of the target 1, the spot 3 is positioned underneath a second pulsed laser beam 9 or other means to heat the target material of the spot 3, such that at least an upper layer of the surface structure of the spot 3 is melted. After solidification, the spot 3 has a smooth surface structure without cones 5 or cracks 6, as is depicted in FIG. 2C.

[0043] Then finally, the spot 3 is moved further by rotation of the target 1 underneath the pulsed laser 4, such that a plasma plume 10 is generated by the irradiation of the pulsed laser 4 on the target 1 at the zone 3. As can be seen in FIG. 2D, the generation of the plasma plume 10 makes the surface structure irregular again up to the structure as depicted in FIG. 2A. Be repeating the smoothing steps the surface structure of zone 3 can be smoothed again.