Magnetron and target producing an extended plasma region in a sputter reactor

• US 6,251,242 B1
• Filed: 01/21/2000
• Issued: 06/26/2001
• Est. Priority Date: 01/21/2000
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Fu, Jianming, Gopalraja, Praburam
• Primary Examiner(s): Huff, Mark F.
• Assistant Examiner(s): CHACKO DAVIS, DABORAH
• Application Number:
  US09/490,026
• Time in Patent Office: 522 Days
• Field of Search: 204/298.19, 204/298.2, 204/298.21, 204/298.22, 204/298.16, 204/298.17, 204/298.18, 204/298.12, 204/192.12, 204/298.08
• US Class Current: 204/298.19
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence
• CPC Class Codes: H01J 37/3405 Magnetron sputtering
• CPC Class Codes: H01J 37/3423 Shape
• CPC Class Codes: H01J 37/3455 Movable magnets
• CPC Class Codes: H01J 37/3458 Electromagnets in particular for cathodic sputtering apparatus electromagnets in general H01F7/06
• CPC Class Codes: H01L 21/2855 by physical means, e.g. sputtering, evaporation H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric

Abstract

A target and magnetron for a plasma sputter reactor. The target has an annular trough facing the wafer to be sputter coated. Various types of magnetic means positioned around the trough create a magnetic field supporting a plasma extending over a large volume of the trough. For example, the magnetic means may include magnets disposed on one side within a radially inner wall of the trough and on another side outside of a radially outer wall of the trough to create a magnetic field extending across the trough, to thereby support a high-density plasma extending from the top to the bottom of the trough. The large plasma volume increases the probability that the sputtered metal atoms will become ionized. The magnetic means may include a magnetic coil, may include additional magnets in back of the trough top wall to increase sputtering there, and may include confinement magnets near the bottom of the trough sidewalls. The magnets in back of the top wall may have an outer magnet surrounding an inner magnet of the opposite polarity. The high aspect ratio of the trough also reduces asymmetry in coating the sidewalls of a deep hole at the edge of the wafer.

Claims

1. A magnetron plasma sputter reactor, comprising:

a plasma chamber arranged about a central axis and configured to accommodate a substrate to be sputter coated;

a target around said central axis and having at least one annular vault disposed on a first side of said target facing said substrate and a well disposed on a back side of said target inside said vault, said vault having an annular inner sidewall, an opposed annular outer sidewall, and a top wall, an aspect ratio of a depth of said vault to a width of said vault being at least 1;

2, said target being configured to received electrical power to create a plasma within said plasma chamber; and

magnetic means disposed at least partially in said well to create a magnetic field having magnetic field lines extending from said inner sidewall to said outer sidewall.

2. The reactor of claim 1, wherein said magnetic means includes permanent magnets.

3. The reactor of claim 1, wherein said magnetic means includes an inductive coil.

4. The reactor of claim 1, where said magnetic means are disposed partially radially outside of said outer sidewall.

5. The reactor of claim 4, wherein said magnetic means are disposed partially above said top wall.

6. The reactor of claim 5, wherein the magnetic means disposed partially above said top wall includes a first magnetic pole of a first polarity and a second magnetic pole of a second polarity opposed to said first polarity and surrounding said first magnetic pole.

7. The reactor of claim 1, wherein said ratio is at least 1:

1.

8. The reactor of claim 7, wherein said magnetic means includes permanent magnets disposed at least partially radially outside of said inner and outer sidewalls from said vault.

9. The reactor of claim 1, wherein said target extends through said vault and to within an area radially inward of said inner sidewall continuously with at least a homogeneous surface portion facing said substrate.

30. The sputter target of claim 9, wherein said radial width is at least 10 cm.

10. A magnetron plasma sputter reactor, comprising:

a plasma chamber arranged about a central axis and configured to accommodate a substrate to be sputter coated;

a target around said central axis and having at least one annular vault disposed on a first side of said target facing said substrate, said vault having a width in a radial direction with respect to said central axis, said target being configured to receive electrical power to create a plasma within said plasma chamber;

a first permanent magnet of a first magnetic polarity along said axis arranged in back of said vault at a first radial distance from said central axis; and

a second permanent magnet of a second magnetic polarity opposite said first polarity disposed in back of said vault at a second radial position from said central axis;

wherein a difference of said first and second radial positions is between 50% and 150% of said width of said vault.

11. The sputter reactor of claim 10, wherein said difference is between 50% and 100% of said width, and said first and second magnets are positioned to create a magnetic flux penetrating a roof of said vault.

12. The sputter reactor of claim 10, wherein said difference is between 100% and 150% of said width, and said first and second magnets are positioned to create a magnetic flux penetrating both sidewalls of said vault.

13. A magnetron plasma sputter reactor, comprising:

a plasma chamber arranged about a central axis and configured to accommodate a substrate to be sputter coated;

a target arranged about said central axis and having at least one annular vault on a first side of said target facing said substrate, a central one of said vaults having an inner vertically extending annular sidewall enclosing a well accessible from a second side of said target and an outer vertically extending annular sidewall opposite said inner side wall, said target being continuous on said first side of said target within said inner sidewall;

a first permanent magnet of a first magnetic polarity disposed in said well and producing a first magnetic field in said vault; and

a second permanent magnet of a second magnetic polarity opposite said first magnetic polarity disposed radially outwardly of said outer sidewall and producing a second magnetic field in said vault.

14. The reactor of claim 13, wherein said second magnet extends only partially around a circumference of said outer sidewall.

15. The reactor of claim 14, wherein said second magnet extends circumferentially around said outer sidewall over an angle of between 20°

to 90°

.

16. The reactor of claim 14, further comprising a motor rotating at least said second magnet about said central axis.

17. The reactor of claim 13, wherein said first and second magnets are magnetized substantially parallel to said central axis and further comprising a magnetic yoke including two arms disposed on respective sides of a back yoke magnetically coupling said two arms.

18. The reactor of claim 13, wherein said central one of said vaults has an aspect ratio of at least 1:

2.

19. The reactor of claim 18, wherein said aspect ratio is at least 1:

1.

20. A magnetron plasma sputter reactor, comprising:

a plasma chamber arranged about a central axis and configured to accommodate a substrate to be sputter coated;

a target arranged about said central axis and having at least one annular vault on a first side of said target facing said substrate, a central one of said vaults having an inner vertically extending annular sidewall enclosing a well accessible from a second side of said target and an outer vertically extending annular sidewall opposite said inner side wall, said target being continuous on said first side of said target within said inner sidewall;

a first paramagnetic material disposed in said well and producing a first magnetic field in said vault;

a second paramagnetic material disposed radially outwardly of said outer sidewall and producing a second magnetic field in said vault;

first and second permanent magnets of opposite magnetic polarities magnetically coupled to said first and second materials on sides of the inner and outer sidewalls opposite said substrate.

21. A magnetron plasma sputter reactor, comprising:

a plasma chamber arranged about a vertically extending central axis and configured to accommodate a substrate to be sputter coated;

a target arranged about said central axis and an annular vault on a first side of said target facing said substrate, said vault having an inner vertically extending annular sidewall enclosing a well accessible from a second side of said target, an outer vertically extending annular sidewall opposite said inner side wall, and a roof connecting said inner and outer sidewalls on a side of said vault opposite said substrate;

a first magnetic pole of a first magnetic polarity disposed in said well;

a second magnetic pole of a second magnetic polarity opposite said first magnetic polarity disposed outside of said outer sidewall and magnetically coupled to said first magnetic pole;

a third magnetic pole of a third, vertical magnetic polarity disposed over said roof; and

a fourth magnetic pole of a fourth, vertical magnetic polarity opposite said third magnetic polarity disposed over said roof and surrounding and magnetically coupled to said third magnetic pole;

wherein said third and fourth magnetic poles at any one time extend only partially around said central axis.

22. The reactor of claim 21, wherein said third and fourth magnetic poles are rotated about said central axis.

23. The reactor of claim 22, wherein said first and second magnetic poles are annularly shaped about and extend around said central axis.

24. The reactor of claim 23, wherein said first and second magnetic poles do not rotate.

25. The reactor of claim 21, wherein said first, second, third, and fourth magnetic poles include respective permanent magnets.

26. The reactor of claim 21, wherein said third magnetic pole overlies only said roof.

27. A sputter target adapted for use with a magnetron sputter reactor, being composed on a least a portion of a first side thereof of a material to be sputtered, and being shaped to have an annular vault on said first side having an aspect ratio of at least 1:

2 and surrounding a central axis, a well on a second side of said target surrounded by and separated from said vault by an inner sidewall, an outer sidewall forming a radially outermost portion of said vault, a roof connecting said inner and outer sidewalls, an outer flange extending radially outwardly from an end of said outer sidewall opposite said roof for being sealed to a vacuum chamber of said reactor, and a cylindrical knob extending from a juncture of said flange and said outer sidewall away from said roof.

28. The target of claim 27, wherein said aspect ratio is at least 1:

1.

29. A sputter target adapted for use with a magnetron sputter reactor, being composed of at least a portion of a first side thereof of a material to be sputtered, and being shaped to have an annular vault on said first side having an aspect ratio of at least 1:

2 and surrounding a central axis and a radial width of at least 5 cm.

31. A magnetron plasma sputter reactor, comprising:

a plasma chamber arranged about a central axis and configured to accommodate a substrate to be sputter coated;

a target around said central axis and having an annular vault disposed on a first side of said target facing said substrate, said vault having a substantially tubular inner sidewall and a substantially tubular outer sidewall both extending substantially in parallel to said central axis and a roof connecting ends of said sidewall opposite said substrate, said target being configured to receive electrical power to create a plasma within said plasma chamber;

a permanent first magnet of a first magnetic polarity along said central axis arranged in back of said roof; and

a permanent second magnet of a second magnetic polarity opposite said first magnetic polarity, surrounding said first magnet, arranged in back of said roof, and not extending at any one time completely around said central axis.

32. The reactor of claim 31, wherein said first and second magnets are rotatable about said central axis.

33. The reactor of claim 31, wherein said first and second magnets are substantially circularly symmetric about an axis passing through said roof.

34. The reactor of claim 31, further comprising third and fourth magnets of opposed magnetic polarities along said central axis arranged respectively in back of said inner and outer sidewalls opposite said vault.

35. The reactor of claim 34, wherein said first and second magnets are rotatable about said central axis.