Near-Substrate Supplemental Plasma Density Generation with Low Bias Voltage within Inductively Coupled Plasma Processing Chamber

• US 20180204708A1
• Filed: 01/17/2017
• Published: 07/19/2018
• Est. Priority Date: 01/17/2017
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Tan, Zhongkui, Zhang, Yiting, Fu, Qian, Xu, Qing, Wu, Ying, Sriraman, Saravanapriyan, Paterson, Alex
• Granted Patent: US 10,242,845 B2
• Time in Patent Office: Days
• CPC Class Codes: C23C 16/0245 by etching with a plasma
• CPC Class Codes: H01J 2237/332 Coating
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/3211 Antennas, e.g. particular shapes of coils
• CPC Class Codes: H01J 37/32119 Windows
• CPC Class Codes: H01J 37/32165 Plural frequencies
• CPC Class Codes: H01J 37/32715 Workpiece holder
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H05H 1/4652 using inductive coupling means, e.g. coils

Abstract

A substrate is positioned on a substrate support structure within a plasma processing volume of an inductively coupled plasma processing chamber. A first radiofrequency signal is supplied from a first radiofrequency signal generator to a coil disposed outside of the plasma processing volume to generate a plasma in exposure to the substrate. A second radiofrequency signal is supplied from a second radiofrequency signal generator to an electrode within the substrate support structure. The first and second radiofrequency signal generators are controlled independent of each other. The second radiofrequency signal has a frequency greater than or equal to about 27 megaHertz. The second radiofrequency signal generates supplemental plasma density at a level of the substrate within the plasma processing volume while generating a bias voltage of less than about 200 volts at the level of the substrate.

Claims

1. A method for operating an inductively coupled plasma processing chamber, comprising:

positioning a substrate on a substrate support structure within a plasma processing volume of the inductively coupled plasma processing chamber;

supplying a first radiofrequency signal from a first radiofrequency signal generator to a coil disposed outside of the plasma processing volume of the inductively coupled plasma processing chamber, the first radiofrequency signal generating a plasma in exposure to the substrate; and

supplying a second radiofrequency signal from a second radiofrequency signal generator to an electrode within the substrate support structure simultaneously with supplying of the first radiofrequency signal from the first radiofrequency signal generator to the coil, the first and second radiofrequency signal generators controlled independent of each other, the second radiofrequency signal having a frequency greater than or equal to about 27 megaHertz, the second radiofrequency signal generating supplemental plasma density at a level of the substrate within the plasma processing volume, the second radiofrequency signal generating a bias voltage of less than about 200 volts at the level of the substrate.

2. The method as recited in claim 1, wherein the first radiofrequency signal is supplied at a frequency within a range extending from about 10 megaHertz to about 15 megaHertz, and wherein the first radiofrequency signal is supplied at a power within a range extending from about 1 kiloWatt to about 4 kiloWatts.

3. The method as recited in claim 1, wherein the second radiofrequency signal is supplied at a frequency within a range extending from about 27 megaHertz to about 140 megaHertz, and wherein the second radiofrequency signal is supplied at a power within a range extending from about 5 Watts to about 1 kiloWatt.

4. The method as recited in claim 1, wherein the second radiofrequency signal is supplied at a frequency of about 27 megaHertz, and wherein the second radiofrequency signal is supplied at a power within a range extending from about 5 Watts to about 1 kiloWatt.

5. The method as recited in claim 1, wherein the second radiofrequency signal is supplied at a frequency of about 60 megaHertz, and wherein the second radiofrequency signal is supplied at a power within a range extending from about 5 Watts to about 1 kiloWatt.

6. The method as recited in claim 1, wherein the coil includes multiple independently controllable radial zones, the method further comprising controlling radiofrequency signals supplied to the multiple independently controllable radial zones of the coil to compensate for a perturbation in plasma density profile across the substrate caused by the supplemental plasma density generated at the level of the substrate by the second radiofrequency signal.

7. The method as recited in claim 1, further comprising:

supplying a third radiofrequency signal from a third radiofrequency signal generator to the electrode within the substrate support structure in accordance with a process recipe performed on the substrate, the first and second and third radiofrequency signal generators controlled independent of each other, the third radiofrequency signal having a frequency within a range extending from about 100 kiloHertz to about 15 megaHertz, the third radiofrequency signal supplied at a power within a range extending from about 5 Watts to about 6 kiloWatts, the third radiofrequency signal generating a bias voltage greater than about 200 volts at the level of the substrate.

8. The method as recited in claim 7, wherein the first radiofrequency signal is supplied at a frequency within a range extending from about 10 megaHertz to about 15 megaHertz, and wherein the first radiofrequency signal is supplied at a power within a range extending from about 1 kiloWatt to about 4 kiloWatts, and

wherein the second radiofrequency signal is supplied at a frequency within a range extending from about 27 megaHertz to about 140 megaHertz, and wherein the second radiofrequency signal is supplied at a power within a range extending from about 5 Watts to about 1 kiloWatt.

9. The method as recited in claim 8, wherein the third radiofrequency signal has a frequency of about 13.56 megaHertz.

10. The method as recited in claim 7, wherein the third radiofrequency signal is supplied from the third radiofrequency signal generator to the electrode within the substrate support structure during directional ion-based processing of the substrate, and wherein the third radiofrequency signal is not supplied from the third radiofrequency signal generator to the electrode within the substrate support structure during isotropic processing of the substrate.

11. The method as recited in claim 7, further comprising:

supplying a fourth radiofrequency signal from a fourth radiofrequency signal generator to the electrode within the substrate support structure in accordance with the process recipe performed on the substrate, the first and second and third and fourth radiofrequency signal generators controlled independent of each other, the fourth radiofrequency signal having a frequency within a range extending from about 100 kiloHertz to about 1 megaHertz, the fourth radiofrequency signal supplied at a power within a range extending from about 5 Watts to about 6 kiloWatts, the fourth radiofrequency signal controlling a directionality of ions at the level of the substrate.

12. The method as recited in claim 11, wherein the first radiofrequency signal is supplied at a frequency within a range extending from about 10 megaHertz to about 15 megaHertz, and wherein the first radiofrequency signal is supplied at a power within a range extending from about 1 kiloWatt to about 4 kiloWatts, and

wherein the second radiofrequency signal is supplied at a frequency within a range extending from about 27 megaHertz to about 140 megaHertz, and wherein the second radiofrequency signal is supplied at a power within a range extending from about 5 Watts to about 1 kiloWatt.

13. The method as recited in claim 12, wherein the third radiofrequency signal has a frequency of about 13.56 megaHertz, and wherein the fourth radiofrequency signal has a frequency of about 1 megaHertz.

14. The method as recited in claim 13, wherein the second radiofrequency signal has a frequency of about 60 megaHertz.

15. The method as recited in claim 13, wherein the second radiofrequency signal has a frequency of about 27 megaHertz.

16. An inductively coupled plasma processing system, comprising:

a chamber enclosing a plasma processing volume, the chamber having an upper window structure;

a coil disposed outside the chamber at location to allow for transmission of radiofrequency signals from the coil through the upper window structure into the plasma processing volume;

a substrate support structure disposed within the chamber, the substrate support structure configured to hold a substrate in exposure to the plasma processing volume;

an electrode disposed within the substrate support structure;

a first radiofrequency signal generator connected to supply a first radiofrequency signal to the coil; and

a second radiofrequency signal generator connected to supply a second radiofrequency signal to the electrode within the substrate support structure, the second radiofrequency signal generator independently controllable relative to the first radiofrequency signal generator, the second radiofrequency signal having a frequency greater than or equal to about 27 megaHertz, the second radiofrequency signal defined to generate supplemental plasma density at a level of the substrate when present upon the substrate support structure, the second radiofrequency signal generating a bias voltage of less than about 200 volts at the level of the substrate when present upon the substrate support structure.

17. The inductively coupled plasma processing system as recited in claim 16, wherein the first radiofrequency signal generator is configured to generate the first radiofrequency signal at a frequency within a range extending from about 10 megaHertz to about 15 megaHertz, and at a power within a range extending from about 1 kiloWatt to about 4 kiloWatts, and

wherein the second radiofrequency signal generator is configured to generate the second radiofrequency signal at a frequency within a range extending from about 27 megaHertz to about 140 megaHertz, and at a power within a range extending from about 5 Watts to about 1 kiloWatt.

18. The inductively coupled plasma processing system as recited in claim 17, further comprising:

a third radiofrequency signal generator connected to supply a third radiofrequency signal to the electrode within the substrate support structure, the third radiofrequency signal generator independently controllable relative to the first and second radiofrequency signal generators, the third radiofrequency signal having a frequency within a range extending from about 100 kiloHertz to about 15 megaHertz, the third radiofrequency signal supplied at a power within a range extending from about 5 Watts to about 6 kiloWatts, the third radiofrequency signal generating a bias voltage greater than about 200 volts at the level of the substrate when present upon the substrate support structure.

19. The inductively coupled plasma processing system as recited in claim 18, further comprising:

a fourth radiofrequency signal generator connected to supply a fourth radiofrequency signal to the electrode within the substrate support structure, the fourth radiofrequency signal generator independently controllable relative to the first and second and third radiofrequency signal generators, the fourth radiofrequency signal having a frequency within a range extending from about 100 kiloHertz to about 1 megaHertz, the fourth radiofrequency signal supplied at a power within a range extending from about 5 Watts to about 6 kiloWatts, the fourth radiofrequency signal controlling a directionality of ions at the level of the substrate when present upon the substrate support structure.

20. The inductively coupled plasma processing system as recited in claim 16, wherein the coil includes multiple independently controllable radial zones, the inductively coupled plasma processing system including a control system configured to control radiofrequency signals supplied to the multiple independently controllable radial zones of the coil to compensate for a perturbation in plasma density profile across the substrate caused by the supplemental plasma density generated at the level of the substrate by the second radiofrequency signal when the substrate is present upon the substrate support structure.