Apparatus for sputtering and a method of fabricating a metallization structure

1. A method of depositing a metallization structure, comprising:

providing a substrate,

depositing a TaN layer by providing a target formed at least in part from tantalum to be sputtered onto the substrate, the depositing of the TaN layer comprising supplying a sputtering gas comprising nitrogen and inert gas, applying a power supply between an anode and a cathode in a plurality of first pulses, and applying a magnetic field adjacent to a surface of the target, the cathode including the target, the first pulses being supplied with a frequency in the range 10 Hz to 1000 Hz and a duty cycle of between 0.01% and 20% and producing a current density of between 0.1 A/cm 2 and 10 A/cm 2 on the target,

during each of the first pulses of the power supply, reactively sputtering tantalum from the target onto the substrate to form a TaN seed layer, the TaN seed layer having a thickness in a range from about 0.2 nm to less than about 1 nm, and

depositing a Ta layer onto the TaN seed layer by providing a magnetic field adjacent to the surface of the target, the depositing of the Ta Layer comprising supplying an inert sputtering gas, applying the power supply between an anode and a cathode in a plurality of second pulses, applying a magnetic field adjacent to a surface of the target, applying a high-frequency signal to a pedestal supporting the substrate to generate a self-bias field adjacent to the substrate, and, during each of the second pulses of the power supply, depositing tantalum from the target onto the TaN seed layer to form the Ta layer, the cathode including the target, the pulses being applied with a frequency in the range 10 Hz to 1000 Hz and a duty cycle of between 0.01% and 20% and producing a current density of between 0.1 A/cm 2 and 10 A/cm 2 on the target,

wherein the high-frequency signal is not applied to the pedestal during the forming of the TaN seed layer and is applied to the pedestal during the depositing of the Ta layer onto the TaN seed layer.

2. The method according to claim 1 , wherein

to deposit the Ta layer onto the TaN layer, the power supply is applied between the anode and cathode before the high-frequency signal first is applied to the pedestal.

3. The method according to claim 1 , wherein

said high-frequency signal is synchronized with said second pulses of said power supply.

4. The method according to claim 1 , wherein

during deposition of the Ta layer, the high-frequency signal is initiated before each of the second pulses of the power supply is applied between the anode and the cathode, maintained while the power supply is applied between the anode and the cathode and for a period of time after each of the second pulses of power supply between the anode and the cathode is terminated, and terminated only after expiration of a period of time after each of the second pulses of power supply between the anode and the cathode is terminated.

5. The method according to claim 1 , wherein

the high-frequency signal has a frequency within a range of about 1 MHz to about 70 MHz.

6. The method according to claim 1 , wherein

the frequency of the first and second pulses of the power supplied between the anode and the cathode to deposit the TaN layer and/or the Ta layer is between 200 Hz and 600 Hz.

7. The method according to claim 1 , wherein

the substrate is a silicon wafer.

8. The method according to claim 1 , wherein

the substrate includes at least one via and inner surfaces of the via are coated with the TaN layer and the Ta layer.

9. The method according to claim 8 , wherein

the via has an aspect ratio of at least 10:1.

10. The method according to claim 8 , wherein

the via extends through a body of the substrate.

11. The method according to claim 8 , wherein

the via forms a portion of a rewiring structure arranged on a planar surface of the substrate.

12. The method according to claim 1 , wherein

the tantalum layer has a body centered cubic crystal structure.

13. The method according to claim 1 , further comprising cooling the substrate during deposition of the TaN seed layer and/or the tantalum layer.

14. The method according to claim 13 , wherein

a gas flow is applied to a rear of the substrate to provide cooling of the substrate.

15. The method according to claim 1 , wherein

the pulse repetition frequency, the duration, deposition time, or any combination thereof is adjusted to deposit the TaN layer with a thickness of less than 5 nm or less than 1 nm or around 0.2 nm.

16. The method according to claim 1 , further comprising depositing copper onto the Ta layer.

17. A method of operating an apparatus to fabricate a metallization structure, the method comprising:

supporting a substrate during sputtering via a pedestal,

providing a magnetic field adjacent to a surface of a target formed at least in part from tantalum to be sputtered onto the substrate via a magnetic assembly,

applying a power supply between an anode and a cathode in a plurality of pulses via a first power supply, the cathode including the target, the pulses having a frequency in the range 10 Hz to 1000 Hz, a duty cycle of between 0.01% and 20% and producing a current density of between 0.1 A/cm 2 and 10 A/cm 2 on the target, and

applying a high-frequency signal to the pedestal supporting the substrate via a second power source electrically connected to the pedestal to generate a self bias field adjacent the substrate,

wherein, to fabricate the metallization structure, the high-frequency signal is not applied to the pedestal during deposition of a TaN seed layer, and the high-frequency signal is applied to the pedestal during deposition of a tantalum layer onto the TaN seed layer, the TaN seed layer having a thickness in a range from about 0.2 nm to less than about 1 nm.

18. The method according to claim 17 , wherein

to deposit the Ta layer onto the TaN layer, the first power supply is applied between the anode and cathode before the high-frequency signal first is applied to the pedestal.

19. The method according to claim 17 , wherein

the high-frequency signal is synchronized with the pulses of the first power supply.

20. The method according to claim 17 , wherein

during deposition of the Ta layer, the high-frequency signal is initiated before each of the pulses of the first power supply is applied between the anode and the cathode, maintained while the first power supply is applied between the anode and the cathode and for a period of time after each of the pulses of first power supply between the anode and the cathode is terminated, and the high-frequency signal is terminated only after expiration of a period of time after each of the pulses of the first power supply between the anode and the cathode is terminated.

21. The method according to claim 17 , wherein

the high-frequency signal has a frequency within a range of about 1 MHz to about 70 MHz.

22. The method according to claim 17 , wherein

the pulses of the first power supply have a frequency in the range 200 Hz to 600 Hz.

23. The method according to claim 17 , wherein

an alpha-tantalum layer is deposited onto the TaN seed layer.

24. The method according to claim 17 , wherein

the substrate is cooled during deposition of the TaN seed layer and/or the Ta layer.

25. The method according to claim 17 , wherein

the first power supply is a DC power supply and the pulses applied between the anode and the cathode are of a DC voltage.