Systems and Methods for Reverse Pulsing

• US 20170372912A1
• Filed: 09/11/2017
• Published: 12/28/2017
• 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
• Granted Patent: US 11,798,785 B2
• Time in Patent Office: Days
• 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 system comprising:

a first radio frequency (RF) generator configured to generate a first radio frequency (RF) pulsed signal having 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;

a plasma chamber coupled to the first RF generator, wherein the plasma chamber is associated with a top coil electrode and has a bottom electrode,

wherein the first RF generator is configured to generate the first RF pulsed signal for supply to the top coil electrode; and

a second RF generator coupled to the bottom electrode, wherein the second RF generator is configured to generate a second RF pulsed signal having a low state for a first time period during which the first RF pulsed signal is in the high state, wherein the second RF pulsed signal has 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 to generate the second RF pulsed signal, the second RF generator is configured to;

transition 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,

transition 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,

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

2. The system 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 system 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 the directionality of the ions in the plasma chamber.

4. The system of claim 1,

wherein to generate the first RF pulsed signal, the first RF generator is configured to:

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

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

wherein to generate the second RF pulsed signal, the second RF generator is configured to;

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

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

5. The system of claim 1,

wherein to generate the first RF pulsed signal, the first RF generator is configured to:

transition 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

transition 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 system of claim 5, wherein to generate the second RF pulsed signal, the second RF generator is configured to:

transition 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

transition 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 system 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 system 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 system 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 system 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 system of claim 1,

wherein the first RF generator is configured to synchronize a transition of the first RF signal with a transition of a digital signal,

wherein the second RF generator is configured to synchronize a transition of the second RF signal with the transition of the digital signal.

12. A system comprising:

a first radio frequency (RF) generator configured to receive a digital signal periodically transitioning between a first state and a second state;

a first match circuit coupled to the first RF generator;

a plasma chamber associated with a top coil electrode and having a bottom electrode, wherein the top coil electrode is coupled to the first match circuit;

wherein the first RF generator is configured to provide a first RF pulsed signal to the first match circuit;

a second RF generator;

a second match circuit coupled to the second RF generator, wherein the second match circuit is coupled to the bottom electrode,

wherein the second RF generator is configured to receive the digital signal and provide a second RF pulsed signal to the second match circuit,

wherein to provide the second RF pulsed signal, the second RF generator is configured to;

synchronize based on the digital signal a low state of the second RF pulsed signal with a high state of the first RF pulsed signal and a high state of the second RF pulsed signal with a low state of the first RF pulsed signal, wherein to synchronize, the second RF generator is configured to;

transition 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 transition 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 the transition of 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.

13. The system of claim 12, wherein the first RF generator is configured to provide the first RF pulsed signal and the second RF generator is configured to provide the second RF pulsed signal such that the ions generated in the plasma chamber are influenced to have increased vertical directionality towards the bottom electrode to process an etch operation of high aspect ratio features.

14. The system of claim 12, wherein to provide the first RF pulsed signal, the first RF generator is configured to synchronize the first RF pulsed signal based on the digital signal, wherein to synchronize the first RF pulsed signal, the first RF generator is configured to:

transition 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;

transition 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.

15. The system of claim 14, wherein to synchronize the second RF pulsed signal, the second RF generator is configured to

transition 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

transition 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.

16. The system of claim 12, 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.

17. The system of claim 12, wherein the digital signal is a clock signal.

18. A system comprising:

a host computer system configured to generate a digital signal;

a first radio frequency (RF) generator coupled to the host computer system to receive the digital signal, wherein upon receiving the digital signal, the first RF generator is configured to generate a first radio frequency (RF) pulsed signal having 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;

a plasma chamber coupled to the first RF generator, wherein the plasma chamber is associated with a top electrode and has a bottom electrode,

wherein the first RF generator is configured to generate the first RF pulsed signal to provide to the top electrode; and

a second RF generator coupled to the host computer system to receive the digital signal, wherein the second RF generator is coupled to the bottom electrode, wherein upon receiving the digital signal, the second RF generator is configured to generate a second RF pulsed signal having a low state for a first time period during which the first RF pulsed signal is in the high state, wherein the second RF pulsed signal has 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 to generate the second RF pulsed signal, the second RF generator is configured to;

transition 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,

transition 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,

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

wherein the second RF generator is configured to generate the second RF pulsed signal to send to the bottom electrode of the plasma chamber.

19. The system of claim 18, wherein the top electrode is one or more RF coils, and the bottom electrode is a chuck of the plasma chamber.

20. The system of claim 18, 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 the directionality of the ions in the plasma chamber.