Systems and methods for reverse pulsing

• US 9,583,357 B1
• Filed: 04/26/2016
• Issued: 02/28/2017
• Est. Priority Date: 08/05/2015
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Long, Maolin, Tan, Zhongkui, Wu, Ying, Fu, Qian, Paterson, Alex, Drewery, John
• Primary Examiner(s): Ahmed, Shamim
• Application Number:
  US15/139,045
• Publication Number:
  US 20170040176A1
• Time in Patent Office: 308 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32128 using particular waveforms, e.g. polarised waves
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing
• CPC Class Codes: H01J 37/32183 Matching circuits
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/32577 Electrical connecting means
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

Systems and methods for reverse pulsing are described. One of the methods includes receiving a digital signal having a first state and a second state. The method further includes generating a transformer coupled plasma (TCP) radio frequency (RF) pulsed signal having a high state when the digital signal is in the first state and having a low state when the digital signal is in the second state. The method includes providing the TCP RF pulsed signal to one or more coils of a plasma chamber, generating a bias RF pulsed signal having a low state when the digital signal is in the first state and having a high state when the digital signal is in the second state, and providing the bias RF pulsed signal to a chuck of the plasma chamber.

Claims

1. A method comprising:

generating a first radio frequency (RF) pulsed signal to have a high state and a low state, wherein the high state of the first RF pulsed signal has a greater amount of power than the low state of the first RF pulsed signal;

providing the first RF pulsed signal to a top coil electrode associated with a plasma chamber;

generating a second RF pulsed signal to have a low state for a first time period during which the first RF pulsed signal is in the high state and to have a high state for a second time period during which the first RF pulsed signal is in the low state, wherein the high state of the second RF pulsed signal has a greater amount of power than the low state of the second RF pulsed signal, wherein generating the second RF pulsed signal includes;

transitioning the second RF pulsed signal from the low state to the high state at a time of transition of the first RF pulsed signal from the high state to the low state; and

transitioning the second RF pulsed signal from the high state to the low state at a time of transition of the first RF pulsed signal from the low state to the high state,

wherein said transitioning the second RF pulsed signal from the low state to the high state at the time of transition of the first RF pulsed signal from the high state to the low state is performed during a conductor etch to control directionality of ions within plasma and to reduce a temperature of electrons within the plasma;

providing the second RF pulsed signal to a bottom electrode of the plasma chamber.

2. The method of claim 1, wherein the top coil electrode is one or more RF coils, and the bottom electrode is a chuck of the plasma chamber.

3. The method of claim 1, wherein the high state of the second RF pulsed signal and the low state of the first RF pulsed signal act to decrease the temperature of the electrons in the plasma chamber, such that the decrease in the temperature assists in enhancing a directionality of the ions in the plasma chamber.

4. The method of claim 1,

wherein generating the first RF pulsed signal comprises:

transitioning the first RF pulsed signal from the high state to the low state within a predetermined amount of time from a transition of a digital signal from a first state to a second state; and

transitioning the first RF pulsed signal from the low state to the high state within a predetermined amount of time from a transition of the digital signal from the second state to the first state,

wherein generating the second RF pulsed signal comprises;

transitioning the second RF pulsed signal from the low state to the high state within a predetermined amount of time from the transition of the digital signal from the first state to the second state; and

transitioning the second RF pulsed signal from the high state to the low state within a predetermined amount of time from the transition of the digital signal from the second state to the first state.

5. The method of claim 1, wherein generating the first RF pulsed signal comprises:

transitioning the first RF pulsed signal from the high state to the low state at a time of a transition of a digital signal from a first state to a second state; and

transitioning the first RF pulsed signal from the low state to the high state at a time of a transition of the digital signal from the second state to the first state.

6. The method of claim 5, wherein generating the second RF pulsed signal comprises:

transitioning the second RF pulsed signal from the low state to the high state at the time of the transition of the digital signal from the first state to the second state; and

transitioning the second RF pulsed signal from the high state to the low state at the time of the transition of the digital signal from the second state to the first state.

7. The method of claim 1, wherein the first RF pulsed signal has zero power during the low state of the first RF pulsed signal and a positive amount of power during the high state of the first RF pulsed signal.

8. The method of claim 7, wherein the second RF pulsed signal has zero power during the low state of the second RF pulsed signal and a positive amount of power during the high state of the second RF pulsed signal.

9. The method of claim 1, wherein the first RF pulsed signal has a positive amount of power during the high state of the first RF pulsed signal and a positive amount of power during the low state of the first RF pulsed signal.

10. The method of claim 9, wherein the second RF pulsed signal has a positive amount of power during the high state of the second RF pulsed signal and a positive amount of power during the low state of the second RF pulsed signal.

11. The method of claim 1, further comprising:

synchronizing a transition of the first RF pulsed signal with a digital signal; and

synchronizing a transition of the second RF pulsed signal with the digital signal,

wherein the digital signal is generated by a clock source, wherein the clock source is located within an RF generator.

12. The method of claim 1, further comprising:

synchronizing a transition of first RF pulsed signal with a digital signal; and

synchronizing a transition of the second RF pulsed signal with the digital signal,

wherein the digital signal is generated by a clock source, wherein the clock source is located within a host system coupled to an RF generator.

13. The method of claim 1, further comprising:

synchronizing a transition of first RF pulsed signal with a digital signal; and

synchronizing a transition of the second RF pulsed signal with the digital signal.

14. A method comprising:

receiving a digital signal periodically transitioning between a first state and a second state; and

providing a first radio frequency (RF) pulsed signal to a top coil electrode associated with a plasma chamber and a second RF pulsed signal to a bottom electrode of the plasma chamber, wherein said providing the first RF pulsed signal includes synchronizing based on the digital signal a high state of the first RF pulsed signal with a low state of the second RF pulsed signal and a low state of the first RF pulsed signal with a high state of the second RF pulsed signal, wherein synchronizing based on the digital signal includes transitioning the second RF pulsed signal from the low state to the high state at a time of transition of the first RF pulsed signal from the high state to the low state and transitioning the second RF pulsed signal from the high state to the low state at a time of transition of the first RF pulsed signal from the low state to the high state, wherein said transitioning the second RF pulsed signal from the low state to the high state at the time of transition of the first RF pulsed signal from the high state to the low state is performed during a conductor etch to control directionality of ions within plasma and to reduce a temperature of electrons within the plasma, wherein the high state of the first RF pulsed signal has a greater amount of power than the low state of the first RF pulsed signal, wherein the high state of the second RF pulsed signal has a greater amount of power than the low state of the second RF pulsed signal.

15. The method of claim 14, wherein providing the first RF pulsed signal occurs is performed while providing the second RF pulsed signal such that the ions generated in the plasma chamber are influenced to have increased vertical directionality towards a chuck to process an etch operation of high aspect ratio features.

16. The method of claim 14, wherein said synchronizing based on the digital signal comprises:

transitioning the first RF pulsed signal from the high state of the first RF pulsed signal to the low state of the first RF pulsed signal when the digital signal transitions from the first state to the second state;

transitioning the first RF pulsed signal from the low state of the first RF pulsed signal to the high state of the first RF pulsed signal when the digital signal transitions from the second state to the first state;

transitioning the second RF pulsed signal from the high state of the second RF pulsed signal to the low state of the second RF pulsed signal when the digital signal transitions from the second state to the first state; and

transitioning the second RF pulsed signal from the low state of the second RF pulsed signal to the high state of the second RF pulsed signal when the digital signal transitions from the first state to the second state.

17. The method of claim 14, wherein the first RF pulsed signal is in the high state when the second RF pulsed signal is in the low state and the first RF pulsed signal is in the low state when the second RF pulsed signal is in the high state.

18. The method of claim 14, wherein the digital signal is a clock signal.