SOFT PULSING

• US 20140305589A1
• Filed: 04/23/2014
• Published: 10/16/2014
• Est. Priority Date: 02/22/2012
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Valcore, John C. Jr.
• Granted Patent: US 10,157,729 B2
• Time in Patent Office: Days
• US Class Current: 156/345.24
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32183 Matching circuits
• CPC Class Codes: H01J 37/32568 Relative arrangement or disposition of electrodes; moving means
• CPC Class Codes: H01J 37/32816 Pressure
• CPC Class Codes: H01J 37/32981 Gas analysis
• CPC Class Codes: H01J 37/3299 Feedback systems

Abstract

Systems and methods for soft pulsing are described. One of the systems includes a master radiofrequency (RF) generator for generating a first portion of a master RF signal during a first state and a second portion of the master RF signal during a second state. The master RF signal is a sinusoidal signal. The system further includes an impedance matching circuit coupled to the master RF generator via an RF cable to modify the master RF signal to generate a modified RF signal and a plasma chamber coupled to the impedance matching circuit via an RF transmission line. The plasma chamber is used for generating plasma based on the modified RF signal. A statistical measure of the first portion has a positive or a

Claims

1. A plasma system comprising:

a master radiofrequency (RF) generator for generating a first portion of a master RF signal during a first state and a second portion of the master RF signal during a second state, wherein the master RF signal is a sinusoidal signal;

an impedance matching circuit coupled to the master RF generator via an RF cable to modify the master RF signal to generate a modified RF signal; and

a plasma chamber coupled to the impedance matching circuit via an RF transmission line, the plasma chamber for generating plasma based on the modified RF signal,

wherein a statistical measure of the first portion has a positive or a negative slope.

2. The plasma system of claim 1, further comprising a slave RF generator for receiving a first portion of a digital pulsed signal during the first state from the master RF generator and a second portion of the digital pulsed signal during the second state from the master RF generator, the slave RF generator for generating a first portion of a slave RF signal during the first state and a second portion of the slave RF signal during the second state,

wherein the slave signal is a sinusoidal signal,

wherein a statistical measure of the first portion of the slave RF signal has a positive slope or a negative slope.

3. The plasma system of claim 2, wherein the statistical measure of the first portion of the slave RF signal has the positive slope during at least a portion of a time in which the statistical measure of the first portion of the master RF signal has the positive slope.

4. The plasma system of claim 2, wherein the statistical measure of the first portion of the slave RF signal has the negative slope during at least a portion of a time in which the statistical measure of the first portion of the master RF signal has the negative slope.

5. The plasma system of claim 1, wherein the master RF signal has frequency and power.

6. The plasma system of claim 1, further comprising:

a gap control system coupled to the master RF generator for generating a first portion of a gap signal during the first state and a second portion of the gap signal during the second state,

wherein the plasma chamber includes a chuck and an upper electrode facing the chuck,

the gap control system further coupled to the upper electrode of the plasma chamber via a motor for changing a gap between the upper electrode and the chuck,

wherein the gap signal has a positive slope or a negative slope.

7. The plasma system of claim 6, wherein the gap control system includes a gap sensor, the gap sensor for determining an amount of the gap between the upper electrode and the chuck.

8. The plasma system of claim 7, further comprising:

a host controller for generating a pulsed signal; and

a phase delay circuit coupled to the host controller for delaying a phase of the pulsed signal based on the amount of the gap, the host controller coupled to the master RF generator via the phase delay circuit.

9. The plasma system of claim 1, further comprising:

a pressure control system coupled to the master RF generator for generating a first portion of a pressure signal during the first state and a second portion of the pressure signal during the second state,

wherein the plasma chamber includes a plurality of confinement rings,

the pressure control system further coupled to the confinement rings via a motor for changing pressure within the plasma chamber,

wherein the first portion of the pressure signal has a positive slope or a negative slope.

10. The plasma system of claim 9, wherein the pressure control system includes a pressure sensor, the pressure sensor for determining an amount of the pressure in the plasma chamber.

11. The plasma system of claim 10, further comprising:

a host controller for generating a pulsed signal; and

a phase delay circuit coupled to the host controller for delaying a phase of the pulsed signal based on the amount of the pressure, the host controller coupled to the master RF generator via the phase delay circuit.

12. The plasma system of claim 1, further comprising:

a flow control system coupled to the master RF generator for generating a first portion of a flow signal during the first state and a second portion of the flow signal during the second state,

the flow control system further coupled to a valve via a motor for controlling a flow rate of a gas to the plasma chamber,

wherein the first portion of the flow signal has a positive slope or a negative slope.

13. The plasma system of claim 12, wherein the flow control system includes a flow sensor, the flow sensor for determining an amount of a flow of one or more gases within the plasma chamber.

14. The plasma system of claim 13, further comprising:

a host controller for generating a pulsed signal; and

a phase delay circuit coupled to the host controller for delaying a phase of the pulsed signal based on the amount of the flow, the host controller coupled to the master RF generator via the phase delay circuit.

15. The plasma system of claim 1, wherein the first state is a high state and the second state is a low state.

16. The plasma system of claim 1, wherein the first state is opposite to the second state.

17. The plasma system of claim 1, wherein the impedance matching circuit modifies the master RF signal by matching an impedance of a load coupled to the impedance matching circuit with that of a source coupled to the impedance matching circuit.

18. The plasma system of claim 1, wherein the statistical measure includes a root mean square value, or a mean value, or a median value, or a peak-to-peak amplitude, or a zero-to-peak amplitude, or a combination thereof.

19. The plasma system of claim 1, wherein each of the positive slope and the negative slope is non-zero and finite.

20. A method comprising:

generating a first portion of a master radiofrequency (RF) signal during a first state and a second portion of the master RF signal during a second state;

matching an impedance of a load with a source based on the master RF signal to produce a modified RF signal, the source including an RF generator and an RF cable, the load including an RF transmission line and a plasma chamber;

receiving the modified RF signal to generate plasma within the plasma chamber,

wherein a statistical measure of the first portion has a positive or a negative slope.

21. The method of claim 20, wherein the statistical measure includes a root mean square value, or a mean value, or a median value, or a peak-to-peak amplitude, or a zero-to- peak amplitude, or a combination thereof.

22. A plasma system comprising:

a first radiofrequency (RF) generator for generating a first portion of a first RF signal during a first state and a second portion of the first RF signal during a second state, wherein the first RF signal is a sinusoidal signal,

wherein the first RF generator is coupled to an impedance matching circuit that is coupled to a plasma chamber,

wherein a statistical measure of the first portion of the first RF signal has a positive slope or a negative slope.

23. The plasma system of claim 22, further comprising:

a second RF generator for generating a first portion of a second RF signal during the first state and a second portion of the second RF signal during the second state, wherein the second RF signal is a sinusoidal signal,

wherein the second RF generator via an RF cable is coupled to the impedance matching circuit; and

wherein a statistical measure of the first portion of the second RF signal has a positive slope or a negative slope.