Method and apparatus for ion milling

• US 10,017,847 B2
• Filed: 06/12/2008
• Issued: 07/10/2018
• Est. Priority Date: 03/05/2007
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Luten, Henry A., Neuman, George A., Olesen, Niels Alfred
• Primary Examiner(s): BRAYTON, JOHN JOSEPH
• Application Number:
  US12/138,206
• Publication Number:
  US 20080302657A1
• Time in Patent Office: 3,680 Days
• Field of Search: 20429812, 20429816, 20429819, 20429836, 20419234, 31511101, 31511111, 31511121, 31511131, 31511141, 31511151, 31511161, 31511171, 31511181, 31511191, 3133591, 3133601, 3133621, 3133631, 3133611, 216 66, 1563454, 335210, 335211, 335212, 335213, 335214, 438712, 438961, 438FOR 117, 438FOR 44, 118723 FI
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/185 by cathodic sputtering
• CPC Class Codes: C23C 14/5833 Ion beam bombardment
• CPC Class Codes: C23C 14/5873 Removal of material
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor

Abstract

The present invention relates to methods and apparatus for ion milling, and more particularly relates to methods and apparatus for smoothing a surface using ion milling.

Claims

1. An anode layer ion source having a central axis and comprising:

an inner cathode;

an outer cathode disposed around said inner cathode with a gap therebetween, said gap defining a loop having a straight portion joined with a turn portion;

an anode disposed as a ring along a perimeter of said inner cathode and proximate said gap between said outer and inner cathodes; and

at least one magnet proximate said inner cathode,

wherein said inner and outer cathodes and said anode are adapted to form, in response to a voltage applied therebetween, an electric field, said electric field having a direction with a component that lies in the same plane along the entire loop and that continuously changes along the turn portion of the loop such that the trajectories of electrons moving along the straight portion of the loop change to follow the turn portion of the loop when the electrons reach the turn portion of the loop, thereby reducing electron loss at said turn portion, and

wherein said at least one magnet is arranged to provide at least a portion of a magnetic field having a direction that changes along the turn portion of the loop, said direction of the magnetic field being different from the direction of the trajectories of the electrons at least at the turn portion of the loop.

2. The anode layer ion source of claim 1, wherein said anode includes a closed-loop facet oblique to said central axis.

3. The anode layer ion source of claim 2, wherein a normal to said closed-loop facet forms an angle of at least about 30 degrees with said central axis.

4. The anode layer ion source of claim 2, wherein a normal to said closed-loop facet forms an angle of at least about 45 degrees with said central axis.

5. The anode layer ion source of claim 2, wherein a normal to said closed-loop facet forms an angle of at least about 60 degrees with said central axis.

6. The anode layer ion source of claim 2, wherein a normal to said closed-loop facet forms an angle of at least about 15 degrees with said central axis.

7. The anode layer ion source of claim 1, further comprising

a magnet component under the inner cathode, and wherein said inner and outer cathodes are configured to form a component of magnetic field that is directed to cause electrons moving along the straight portion of said loop change their trajectories and turn into the turn portion of said loop and that causes reduction of electron loss upon such turning into said turn portion.

8. The anode layer ion source of claim 1, further comprising

a first set of magnets disposed under the inner cathode, and

a second set of magnets placed under the outer cathode around a perimeter of a turning portion of said loop, and

wherein said inner and outer cathodes are configured to form a component of magnetic field that is directed to cause electrons moving along the straight portion of said loop change their trajectories and turn into the turn portion of said loop and that causes reduction of electron loss upon such turning into said turn portion.

9. The anode layer ion source of claim 1, wherein the magnetic field has magnetic flux in the gap of at least about 2600 gauss.

20. The anode layer ion source of claim 1, and further comprising

a first set of magnets disposed under the inner cathode, and

a second set of magnets disposed under the outer cathode outside and around a perimeter of said loop to form a magnetic field having a component that is directed to cause electrons moving along a straight portion of said loop change their trajectories and turn into a turn portion of said loop and that causes reduction of electron loss upon such turning into said turn portion.

21. The anode layer ion source of claim 1, further comprising a set of threadless dowel pins positioned to electrically insulate said anode from a body of said anode layer ion source thereby minimizing a volume occupied by said anode layer ion source, said set of threadless dowel pins including first dowel pins and second dowel pins, a first dowel pin being adapted to restrain said anode in a first direction substantially perpendicular to said backplate and in a second direction substantially along said backplate, a second dowel pin being adapted to restrain said anode in a third direction substantially perpendicular to the second direction.

10. An anode layer ion source comprising:

a plurality of pairs of cathodes, cathodes in each pair having a gap therebetween, said gap defining a corresponding planar loop containing straight portions joined by turn portions;

a plurality of anodes respectively corresponding to the plurality of pairs of cathodes, each anode being disposed as a ring along a perimeter of a cathode in a corresponding pair of cathodes near a corresponding gap;

at least one magnet proximate a cathode of each pair of cathodes,

wherein, by tuning magnetic field strength of said at least one magnet around at least a portion of said turn portions to form, in response to voltages applied respectively between pairs of cathodes and corresponding anodes and a magnetic field formed across said gaps, electrons in said gaps are caused to travel along corresponding planar loops; and

a back plate extending along a plurality of planar loops and corresponding to said plurality of pairs of cathodes, the back plate defining a magnetic backplane common to said plurality of pairs of cathodes,

wherein said tuning magnetic field strength of said at least one magnet includes at least one of;

having a different magnetic field strength or direction at said turn portion than said straight portion; and

rotating a magnetic field at said turn portion, such that said magnetic field at said turn portion is different than at said straight portion,

wherein an anode from the plurality of anodes is electrically insulated from a body of the anode layer ion source with a set of threadless dowel pins including first dowel pins and second dowel pins, and

wherein a first dowel pin is adapted to support said anode in a first direction substantially perpendicular to said back plate and in a second direction substantially along said back plate, and a second dowel pin is adapted to support said anode in a third direction substantially perpendicular to the second direction such as to minimize a volume occupied by said anode layer ion source.

11. The anode layer ion source of claim 10 and further comprising magnetic components forming said magnetic field, and wherein said plurality of pairs of cathodes and said plurality of respectively corresponding anodes are configured such as to form corresponding electric fields having electric field components that are directed to cause electrons moving along the straight portions of said planar loops change their trajectories and turn into the turn portions of said planar loops and that are directed to cause reduction of electron loss upon such turning into said turn portions.

12. The anode layer ion source of claim 10, wherein an anode from the plurality of anodes contains a closed-loop facet that is oblique to a central axis of the ion source, and

wherein the strength of a magnetic flux in a gap corresponding to a pair of cathodes is at least about 2600 gauss.

22. The anode layer ion source of claim 10, wherein the first and second dowel pins are located to minimize movement of said anode relative to said cathode and back plate.

13. An anode layer ion source comprising:

an inner cathode;

an outer cathode disposed around said inner cathode with a gap therebetween defining a loop having straight portions joined by turn portions and a loop plane;

an anode disposed below said gap between said cathodes,

a first row of magnets under the inner cathode and defining a magnetic field traversing said gap; and

a second row of magnets disposed under the outer cathode outside and around a perimeter of said loop, the first and second row of magnets configured to form a magnetic field having a magnetic flux in the gap;

wherein said inner and outer cathodes and said anode are adapted by tuning magnetic field strength of at least one of said first row of magnets and said second row of magnets to form, in response to a voltage applied therebetween,

a) an electric field having a component that is directed to cause electrons moving along a straight portion of said loop change their trajectories and turn into a turn portion of said loop, and

b) a magnetic field having a vector that is inclined, with respect to said loop plane, at a first angle in a straight portion of the loop and at a second angle in a turn portion of the loop, the first and second angles being different

wherein said tuning magnetic field strength of said at least one magnet includes at least one of;

having a different magnetic field strength or direction at said turn portion than said straight portion; and

rotating a magnetic field at said turn portion, such that said magnetic field at said turn portion is different than at said straight portion.

14. The anode layer ion source of claim 13, wherein the magnetic flux is at least about 5000 gauss.

15. The anode layer ion source of claim 14, wherein the magnetic flux is at least about 7500 gauss.

16. The anode layer ion source of claim 13, wherein the magnetic flux is at least about 2600 gauss at both turning portions of said loop.

17. The anode layer ion source of claim 13, wherein the magnetic flux is at least about 2600 gauss at substantially all locations along said loop.

18. The anode layer ion source of claim 13, wherein the magnetic flux is greater at either of the turning portions of said loop than at straight portions of said loop.

19. The anode layer ion source of claim 13, wherein the first angle is smaller than the second angle.