Integrated process for copper via filling using a magnetron and target producing highly energetic ions

• US 6,277,249 B1
• Filed: 03/02/2000
• Issued: 08/21/2001
• Est. Priority Date: 01/21/2000
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Dixit, Girish, Wang, Wei D., Xu, Zheng, Fu, Jianming, Gopalraja, Praburam, Chen, Fusen, Sinha, Ashok K., Athreya, Sankaram
• Primary Examiner(s): Huff, Mark F.
• Assistant Examiner(s): CHACKO DAVIS, DABORAH
• Application Number:
  US09/518,180
• Time in Patent Office: 537 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, 204/192.15, 204/192.17
• US Class Current: 204/192.12
• 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 37/342 Hollow targets
• 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 21/76805 the opening being a via or contact hole penetrating the underlying conductor
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76844 Bottomless liners
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76865 Selective removal of parts of the layer H01L21/76844 takes precedence
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 2221/1089 Stacks of seed layers

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. An integrated copper via filling process includes a first step of highly ionized sputter deposition of copper, a second step of more neutral, lower-energy sputter deposition of copper to complete the seed layer, and electroplating copper into the hole to complete the metallization.

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, 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 polarization positioned in back of one sidewall of said vault; and

a second permanent magnet of a second magnetic polarization opposite said first polarization disposed in back of another sidewall of said vault.

2. The sputter reactor of claim 1, further comprising:

a third magnet of a third magnetic polarization positioned in back of a roof of said vault;

a fourth magnet of a fourth magnetic polarization opposite said third magnetic polarization positioned in back of said roof of said vault and substantially surrounding said third magnet; and

a support rotating about said central axis and supporting said third and fourth magnets.

3. The sputter reactor of claim 2, wherein said first and second magnets are annular.

4. The sputter reactor of claim 3, wherein said support supports said first and second magnets.

5. The sputter reactor of claim 2, wherein said first and second magnets are fully annular about said central axis and wherein said third and fourth magnets are rotated about said central axis.

6. The sputter reactor of claim 2, wherein said fourth magnet has a higher total magnetic flux than does said third magnet.

7. The sputter reactor of claim 2, wherein said third and fourth magnets extend only partially around said central axis.

8. The sputter reactor of claim 7, wherein said composition comprises copper.

9. The sputter reactor of claim 1, wherein said first and second magnets have substantially same lengths.

10. The sputter reactor of claim 1, wherein said first and second magnets have differing lengths.

11. The sputter reactor of claim 1, wherein one of the first and second magnets closer to said central axis is shorter than the other of the first and second magnets.

12. The sputter reactor of claim 1, wherein at least one of the first and second magnets is rotatable about said central axis.

13. The sputter reactor of claim 1, wherein said vault has an aspect ratio of a depth thereof to said width of at least 1:

2.

14. The sputter reactor of claim 13, wherein said aspect ratio is at least 1:

1.

15. The sputter reactor of claim 1, wherein said sidewalls extend substantially parallel to said central axis.

16. A high-energy sputtering method comprising:

placing a magnetron in back of a copper target included in one side of a chamber;

biasing said copper target with a first level of a DC power to excite a plasma to sputter said target;

biasing a pedestal holding a substrate to a second level of a negative DC bias;

maintaining a pressure in said chamber to a third level of a pressure;

wherein said first and second levels are large enough and said third level small enough to cause a distribution of energies of copper ions in said plasma to have a peak energy in a range of 50 to 300 eV.

17. The method of claim 16, wherein a ratio of argon ions to copper ions in said plasma is 0.2 or less.

18. The sputter reactor of claim 16, further comprising rotating said magnetron in back of said copper target.

19. A magnetron sputter reactor, comprising:

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

a sputtering target disposed about said central axis and having an annular vault disposed on a first side of said target facing said substrate and extending around said central axis, said vault having an inner sidewall and an outer sidewall extending substantially in parallel to said central axis and a roof between said inner and outer sidewalls, a ratio of a depth of said vault to a width of said vault in a radial direction with respect said central axis being at least 1;

2, said target being configured to receive electrical power to support a plasma within said plasma chamber;

a first permanent magnet of a first magnetic polarity positioned in back of said inner sidewall; and

a second permanent magnet of a second magnetic polarity opposite said first magnetic polarity positioned in back of said outer sidewall.

20. The sputter reactor of claim 19, wherein said first and second magnets are annular about said central axis.

21. The sputter reactor of claim 19, further comprising:

a third magnet of a third magnetic polarity positioned in back of said roof of said vault;

a fourth magnet of a fourth magnetic polarity opposite said third magnetic polarity positioned in back of said roof of said vault and surrounding said third magnet; and

a support rotatable about said central axis and supporting said third and fourth magnets.

22. The sputter reactor of claim 21, wherein said first and second magnets are annular about said central axis.

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

a first magnet of a first magnetic polarization positioned in back of one sidewall of said vault; and

a second magnet of a second magnetic polarization opposite said first polarization disposed in back of another sidewall of said vault.

24. The sputter reactor of claim 23, further comprising:

a third magnet of a third magnetic polarization positioned in back of a roof of said vault;

a fourth magnet of a fourth magnetic polarization opposite said third magnetic polarization positioned in back of said roof of said vault and substantially surrounding said third magnet; and

a support rotating about said central axis and supporting said third and fourth magnets.

25. The sputter reactor of claim 24, wherein said first and second magnets are annular.

26. The sputter reactor of claim 25, wherein said support supports said first and second magnets.

27. The sputter reactor of claim 24, wherein said third and fourth magnets extend only partially around said central axis.