Electron cyclotron rotation (ECR)-enhanced hollow cathode plasma source (HCPS)
Techniques are disclosed for an electron cyclotron rotation (ECR)-enhanced hollow cathode plasma source (HCPS). A cylindrical magnet is placed around the neck of a hollow cathode under the influence of an RF field. A plasma gas is introduced in the hollow cathode that undergoes phase transition to a plasma containing free electrons and gas ions. The magnetic field of the magnet causes ECR that confines free electrons to a narrow spiraling beam traveling down the body of the hollow cathode. Unlike traditional methods, the present ECR-enhanced design confines the electrons and ions to a narrow path away from the walls of the cathode. The high-density, stable plasma is available at the distal end of the hollow cathode. A multicavity design utilizes multiple cavities with multiple aligned magnets in a single reactor suitable for various processes including, PECVD, PEALD, ALE, etc.
1. A hollow cathode plasma source (HCPS) comprising:
(a) one or more cylindrical and aligned magnets around each of corresponding one or more hollow cathodes;
(b) a gas flown through a neck of said each of corresponding one or more hollow cathodes;
(c) a radio frequency (RF) field present around said each of corresponding one or more hollow cathodes, said RF field causing said gas to undergo a phase transition to a plasma containing free electrons and gas ions;
(d) said free electrons traveling in a spiraling beam down a body of said each of corresponding one or more hollow cathodes; and
(e) said spiraling beam confined by electron cyclotron rotation (ECR) caused by each of said one or more cylindrical and aligned magnets;
wherein said plasma is produced at a distal end of said each of corresponding one or more hollow cathodes.
2. The HCPS of claim 1 , wherein a frequency of said RF field is substantially 13.56 Megahertz (MHz).
3. The HCPS of claim 1 , wherein said each of corresponding one or more hollow cathodes is bottle-shaped.
4. The HCPS of claim 1 , wherein a cyclotron radius of said free electrons in said each of corresponding one or more hollow cathodes is approximately 1.8 microns.
5. The HCPS of claim 1 , wherein said distal end of said each of corresponding one or more hollow cathodes transmits said plasma through a corresponding output hole located on a bottom of a showerhead placed above a process volume.
6. The HCPS of claim 5 , wherein said one or more cylindrical and aligned magnets are cooled by an arrangement comprising a thermally conducting ceramic plate, a cooling plate and water.
7. The HCPS of claim 6 , wherein said showerhead also contains pinholes for injecting one or more process gases in said process volume.
8. The HCPS of claim 7 , wherein said process volume is used for depositing one or more plasma enhanced chemical vapor deposition (PECVD) films on a substrate located below said showerhead.
9. The HCPS of claim 7 , wherein said process volume is used for depositing one or more atomically sized plasma enhanced atomic layer deposition (PEALD) films on a substrate located below said showerhead.
10. The HCPS of claim 7 , wherein said process volume is used for performing atomic layer etching (ALE) on a substrate located below said showerhead.
11. A method comprising the steps of:
(a) placing one or more cylindrical and aligned magnets around each of corresponding one or more hollow cathodes;
(b) flowing a gas through a neck of said each of corresponding one or more hollow cathodes;
(c) producing a radio frequency (RF) field around said each of corresponding one or more hollow cathodes, said RF field causing said gas to undergo a phase transition to a plasma containing free electrons and gas ions;
(d) said free electrons traveling in a spiraling beam down a body of said each of corresponding one or more hollow cathodes;
(e) confining said spiraling beam by electron cyclotron rotation (ECR) caused by each of said one or more cylindrical and aligned magnets; and
(f) producing said plasma at a distal end of said each of corresponding one or more hollow cathodes.
12. The method of claim 11 , establishing said RF field at a frequency of substantially 13.56 Megahertz (MHz).
13. The method of claim 11 , providing said each of corresponding one or more hollow cathodes to be bottle-shaped.
14. The method of claim 11 , providing a cyclotron radius of said free electrons in said each of corresponding one or more hollow cathodes to be approximately 1.8 microns.
15. The method of claim 11 , transmitting said plasma from said distal end of said each of corresponding one or more hollow cathodes through a corresponding output hole located on a bottom of a showerhead placed above a process volume.
16. The method of claim 15 , cooling said one or more cylindrical and aligned magnets by an arrangement containing a thermally conductive ceramic plate, a cooling plate and water.
17. The method of claim 15 , further providing pinholes in said showerhead for injecting one or more process gases in said process volume from a trap volume.
18. The method of claim 17 , depositing one or more plasma enhanced chemical vapor deposition (PECVD) films on a substrate located in said process volume below said showerhead.
19. The method of claim 17 , depositing one or more atomically sized plasma enhanced atomic layer deposition (PEALD) films on a substrate located in said process volume below said showerhead.
20. The method of claim 17 , performing atomic layer etching (ALE) on a substrate located in said process volume below said showerhead.