Pulsed sputtering with a small rotating magnetron

• US 6,413,382 B1
• Filed: 11/03/2000
• Issued: 07/02/2002
• Est. Priority Date: 11/03/2000
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Wang, Wei, Xu, Zheng, Fu, Jianming, Gopalraja, Praburam
• Primary Examiner(s): VerSteeg, Steven H.
• Application Number:
  US09/705,324
• Time in Patent Office: 606 Days
• Field of Search: 204/192.12, 204/298.08, 204/298.17, 204/298.2, 204/298.22
• US Class Current: 204/192.12
• CPC Class Codes: H01J 37/3408 Planar magnetron sputtering
• CPC Class Codes: H01J 37/3444 Associated circuits
• CPC Class Codes: H01J 37/3455 Movable magnets

Abstract

A magnetron sputter reactor having a target that is pulsed with a duty cycle of less than 10% and preferably less than 1% and further having a small magnetron of area less than 20% of the target area rotating about the target center, whereby a very high plasma density is produced during the pulse adjacent to the area of the magnetron. The power pulsing frequency needs to be desynchronized from the rotation frequency so that the magnetron does not overlie the same area of the magnetron during different pulses. Advantageously, the power pulses are delivered above a DC background level sufficient to continue to excite the plasma so that no ignition is required for each pulse.

Claims

1. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target;

a magnetron having an area of less than 20% of the area of the target and being rotatable about a back of said target; and

a power supply connected to said target and delivering pulses of power of negative voltage with a duty cycle of less than 10%.

2. The reactor of claim 1, wherein said duty cycle is less than 1%.

3. The reactor of claim 1, wherein said pulses have a power pulse width of no more than 1ms.

4. The reactor of claim 3, wherein said pulse width is no more than 200 μ

s.

5. The reactor of claim 1, wherein said magnetron comprises a closed outer pole of one magnetic polarity surrounding an inner pole of a second magnetic polarity.

6. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target;

a magnetron having an area of less than 20% of the area of the target and being rotatable about a back of said target; and

a power supply connected to said target and delivering pulses of power with a duty cycle of less than 10%;

wherein said power supply delivers said pulses braving a peak power level rising from a background power level, whereby power delivered from said power supply does not fill below a finite level between said pulses, whereby a plasma is continuously maintained in said reactor between said pulses.

7. The reactor of claim 6, wherein a ratio of said peak power level to said finite level is at least 10.

8. The reactor of claim 7, wherein said ratio is at least 100.

9. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target;

a magnetron positioned at a back of said target;

an adjustable DC power supply connected to said target delivering a selected negative DC voltage;

a pulsed power supply connected in parallel with said adjustable DC power supply and delivering pulses of negative voltage with a duty cycle of less than 10%; and

a motor for rotating said magnetron at a rotation frequency and wherein said power supply delivers said pulses at a repetition frequency, wherein said rotation frequency is desynchronized from said repetition frequency such that said pulses are delivered at respective times at which said magnetron is respectively positioned at at least ten different angular positions at said back of said target.

10. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target;

a magnetron positioned at a back of said target;

an adjustable DC power supply connected to said target delivering a selected negative DC voltage; and

a pulsed power supply connected in parallel with said adjustable DC power supply and delivering pulses of negative voltage with a duty cycle of less than 10%.

11. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target;

a magnetron positioned at a back of said target;

an adjustable DC power supply connected to said target delivering a selected negative DC voltage; and

a pulsed power supply connected in parallel with said adjustable DC power supply and delivering pulses of negative voltage with a duty cycle of less than 1%.

12. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target;

a magnetron positioned at a back of said target;

an adjustable DC power supply connected to said target delivering a selected negative DC voltage; and

a pulsed power supply connected in parallel with said adjustable DC power supply and delivering pulses of negative voltage with a duty cycle of less than 10%;

wherein said adjustable DC power supply is effective at igniting and maintaining a plasma in said plasma sputter reactor without use of said pulsed power supply.

13. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target;

a magnetron positioned at a back of said target, wherein said magnetron is rotatable about a central axis of said target and has an area of no more than 20% of that of said target;

an adjustable DC power supply connected to said target delivering a selected negative DC voltage; and

a pulsed power supply connected in parallel with said adjustable DC power supply and delivering pulses of negative voltage with a duty cycle of less than 10%.

14. A method of operating a sputter reactor, comprising the steps of:

rotating a magnetron about the back of a target of the reactor, said back being on an opposite side of said target than a front thereof facing a substrate to be sputter coated, said magnetron having an area of no more than 20% of an area of said target; and

applying pulses of power of negative voltage to said target to excite a plasma in said reactor, said pulses having a duty cycle of less than 10%.

15. The method of claim 14, wherein said duty cycle is less than 1%.

16. The method of claim 14, wherein said pulses comprises substantially DC power during said pulses.

17. A method of operating a sputter reactor, comprising the steps of

rotating a magnetron about the back of a target of the reactor, said back being on an opposite side of said target than a front thereof facing a substrate to be sputter coated, said magnetron having an area of no more than 20% of an area of said target;

applying pulses of power to said target to excite a plasma in said reactor, said pulses having a duty cycle of less than 10%; and

applying at least a minimum level of power to said target between said pulses sufficient to maintain said plasma in a chamber of said sputter reactor between said pulses.

18. The method of claim 17,

wherein said step of applying pulses applies a peak level of power to said target; and

wherein said step of applying at least a minimum level of power applies a background level; and

wherein a ratio of said peak level to said background level is at least 10.

19. The method of claim 18, wherein said ratio is at least 100.

20. The method of claim 19, wherein said ratio is at least 1000.

21. A multi-step sputtering process performed in a sputter reactor including a pulsed power supply delivering a sequence of pulses at a duty cycle to a target, said process comprising the steps of:

a first step of delivering said pulses at a first duty cycle to said target to irradiate a substrate with particles sputtered from said target; and

a second step of delivering said pulses at a second duty cycle different from said first duty to said target to irradiate said substrate with particles sputtered from said target;

wherein at least one of said duty cycles is less than 10%.

22. The process of claim 21, wherein said at least one of said duty cycles is less than 1%.

23. The process of claim 21, wherein said first duty cycle is less than said second duty cycle.

24. The process of claim 21, further comprising, during said first and second steps, rotating about a central axis of said target a magnetron having an area of no more than 20% of that of said target.

25. The process of claim 21, wherein said pulsed power supply is limited by the energy in each of said pulses.

26. A pulsed magnetron sputter reactor, comprising:

a plasma sputter reactor having a target and a pedestal for supporting a substrate to be sputter deposited in opposition to said target and an anode with respect to a cathode of said target;

a magnetron rotatable about a back of said target; and

a power supply connected to said target and delivering pulses to said target of power of negative voltage with respect to said anode and having a duty cycle of less than 10%.

27. A method of operating a sputter reactor, comprising the steps of:

rotating a magnetron about the back of a target of the reactor, said back being on an opposite side of said target than a front thereof facing a substrate to be sputter coated, said reactor having an anode with respect to a cathode of said target; and

applying to said target pulses of power of negative power with respect to said anode target to excite a plasma in said reactor, said pulses having a duty cycle of less than 10%.