Stable high rate reactive sputtering

• US 6,537,428 B1
• Filed: 09/02/1999
• Issued: 03/25/2003
• Est. Priority Date: 09/02/1999
• Status: Expired due to Fees

• Current Assignee: Veeco Instruments Incorporated
• Original Assignee: Veeco Instruments Incorporated
• Inventors: Xiong, Wei, Gupta, Subhadra
• Primary Examiner(s): Huff, Mark F.
• Assistant Examiner(s): CHACKO DAVIS, DABORAH
• Application Number:
  US09/389,861
• Time in Patent Office: 1,300 Days
• Field of Search: 204/192.13, 204/192.15, 204/298.03, 204/298.08, 204/298.07, 204/192.22, 204/192.23, 204/192.26
• US Class Current: 204/192.13
• CPC Class Codes: C23C 14/0036 Reactive sputtering
• CPC Class Codes: C23C 14/0094 in transition mode
• CPC Class Codes: C23C 14/54 Controlling or regulating the coating process
• CPC Class Codes: H01J 37/34 operating with cathodic sputtering H01J37/36 takes precedence ; methods of cathodic sputtering C23C14/34
• CPC Class Codes: H01J 37/3444 Associated circuits

Abstract

A method and apparatus for monitoring and controlling reactive sputter deposition, particularly useful for depositing insulating compounds (e.g., metal-oxides, metal-nitrides, etc.). For a given nominal cathode power level, target material, and source gases, the power supplied to the cathode (target) is controlled to stabilize the cathode (target) voltage at a specified value or within a specified range corresponding to a partial pressure or relative flow rate value or range of the reactive gas. Such an operating point or range, characterized by a specified voltage value or range and corresponding reactive gas relative-flow/partial-pressure value or range, may be determined empirically based on measuring the cathode voltage as a function of reactive gas relative-flow/partial-pressure for the given nominal power. This relationship is typically a hysteresis curve, and preferably the operation point is selected at or near the hysteresis transition edge to provide high rate deposition of high quality films, including insulating or dielectric films using a metallic target.

Claims

1. A method for controlling a sputter deposition process involving reaction between a reactive species and a material included in a target acting as a cathode, said method comprising the steps of:

establishing a reactive sputter deposition process at an approximate operating point corresponding to an approximate cathode voltage of said cathode, a given flow rate or partial pressure of a reactive gas, and a given power supplied to said cathode, wherein said approximate operating point corresponds to a transition region between a low slope metal mode and a low slope compound mode of a hysteresis curve that represents the voltage of said cathode as a function of the flow rate or partial pressure of said reactive gas for said given power supplied to said cathode; and

stabilizing the reactive sputter deposition at said approximate operating point by adjusting the power supplied to said cathode to maintain said approximate cathode voltage of said cathode.

2. The method according to claim 1, wherein said target is electrically conducting and a compound formed from the reaction is electrically non-conducting.

3. The method according to claim 1, wherein the sputter deposition of a compound onto a substrate is at a rate at least about 50% of a rate of deposition of the target in a metal mode corresponding to operating without the presence of said reactive gas at substantially the same power conditions.

4. The method according to claim 1, wherein said target is a material selected from the group consisting of aluminum, titanium, tantalum, zinc, hafnium, zirconium, chromium, silicon and mixtures thereof.

5. The method according to claim 1, wherein said compound is selected from the group consisting of oxides, nitrides, carbides, sulfides, fluorides, chlorides, borides, and mixtures thereof.

6. The method according to claim 1, wherein said approximate cathode voltage and said approximate flow rate or partial pressure of the reactive gas or reactive species are selected to provide desired characteristics of a film formed by said reactive sputter deposition.

7. The method according to claim 1, wherein said power supplied to the cathode is non-pulsed, direct current power, or pulsed power, or RF power.

8. The method according to claim 1, wherein said step of establishing reactive sputter deposition includes initially stabilizing the reactive sputter deposition process conditions by establishing said approximate flow rate or partial pressure of the reactive gas;

and applying an initial power determined according to said operating point.

9. A method for controlling a sputter deposition process involving reaction between a reactive species and a material included in a target acting as a cathode, said method comprising the steps of:

initiating a reactive sputter deposition process at a given flow rate or partial pressure of the reactive species; and

stabilizing the voltage of said cathode at an approximate cathode voltage by adjusting the given power supplied to the cathode to balance the arrival and removal rate of said reactive species at the target, wherein said given flow rate or partial pressure of the reactive species, said approximate cathode voltage, and said given power correspond to a transition region between a low slope metal mode and a low slope compound mode of a hysteresis curve that represents the voltage of said cathode as a function of the flow rate or partial pressure of said reactive species for said given power supplied to said cathode.

10. A reactive sputter deposition apparatus, comprising:

a vacuum chamber;

an anode;

a reactive gas source that provides a reactive gas into the vacuum chamber, the reactive gas characterized by a given partial pressure in the chamber or given flow rate into the chamber;

a target as a cathode in the vacuum chamber and including a material to be combined with reactive species corresponding to the reactive gas to form a compound;

a power source electrically coupled to said target such that said target may be selectively powered by the power source to excite the reactive gas to generate the reactive species that combine with the material of the target to form the compound;

a control device that senses a signal representative of the voltage at said cathode and provides a control signal to said power source such that the power supplied to the cathode is adjusted to stabilize the cathode voltage at an approximate voltage, wherein said approximate voltage and said given flow rate or given partial pressure of the reactive gas correspond to a transition region between a low slope metal mode and a low slope compound mode of a hysteresis curve that represents the cathode voltage as a function of the flow rate or partial pressure of the reactive gas at a given power supplied by said power source to the cathode.

11. The reactive sputter deposition apparatus according to claim 10, wherein said target is electrically conducting and said compound is electrically non-conducting.

12. The reactive sputter deposition apparatus according to claim 10, wherein the deposition of said compound onto a substrate is at a rate at least about 50% of a rate of deposition of the target in a metal mode corresponding to operating without the presence of said reactive gas at substantially the same power conditions.

13. The reactive sputter deposition apparatus according to claim 10, wherein said power source is a non-pulsed, direct current power source.

14. A reactive sputter deposition apparatus, comprising:

a vacuum chamber;

an anode;

a reactive gas source that provides a reactive gas into the vacuum chamber, the reactive gas characterized by a given partial pressure in the chamber or given relative flow rate into the chamber;

a target as a cathode in the vacuum chamber and including a material to be combined with reactive species corresponding to the reactive gas to form a compound;

a power source electrically coupled to said target such that said target may be selectively powered by the power source;

a control device that senses a signal representative of the voltage at said cathode and provides a control signal to said power source such that the power supplied to the cathode is adjusted to balance the arrival and removal rate of said reactive species at the target to stabilize deposition of the compound on a transition region between a low slope metal mode and a low slope compound mode of a hysteresis curve that represents the voltage of said cathode as a function of the flow rate or partial pressure of said reactive species at a given power supplied to said cathode.

15. A reactive sputter deposition apparatus, comprising:

a vacuum chamber;

an anode;

a reactive gas source that provides a reactive gas into the vacuum chamber, the reactive gas characterized by a given partial pressure in the chamber or given relative flow rate into the chamber;

a target as a cathode in the vacuum chamber and including a material to be combined with reactive species that correspond to the reactive gas to form a compound;

a power source electrically coupled to said target such that said target may be selectively powered by the power source;

means for controlling the power source to stabilize deposition of the compound on a transition region between a low slope metal mode and a low slope compound mode of a hysteresis curve that represents the voltage of said cathode as a function of the flow rate or partial pressure of said reactive species at a given power supplied to said cathode.

16. The reactive sputtering apparatus according to claim 15, wherein said means for controlling the power source senses a signal representative of the voltage at said cathode and provides a control signal to said power source such that the power supplied to the cathode is adjusted to balance the arrival and removal rate of said reactive species at the target.

17. The reactive sputtering apparatus according to claim 15, wherein said means for controlling the power source senses a signal representative of the voltage at said cathode and provides a control signal to said power source such that the power supplied to the cathode is adjusted to stabilize the cathode voltage of said cathode.

18. A method for controlling a sputter deposition process involving reaction between a reactive gas and a material included in a target acting as a cathode, said method comprising the steps:

sensing a signal representative of a sputter parameter that is rapidly or directly responsive to power supplied to the cathode; and

stablizing the sputter parameter by controlling the power supplied to the cathode based on the deviation between the sensed signal representative of the sputter parameter and a signal representative of the desired approximate value or range of the sputter parameter to stabalize deposition on a transition region between a low slope metal mode and a low slope compound mode of a hysteresis curve that represents the voltage of said cathode as a function of the flow rate or partial pressure of said reactive species at a given power supplied to said cathode.

19. The method according to claim 18, wherein said sputter parameter is cathode voltage.