Direct Current Pulsing Plasma Systems

• US 20170250056A1
• Filed: 12/02/2016
• Published: 08/31/2017
• Est. Priority Date: 02/29/2016
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Boswell, Roderick W., Gottscho, Richard Alan
• Granted Patent: US 9,966,231 B2
• Time in Patent Office: Days
• 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 37/32091 the radio frequency energy being capacitively coupled to the plasma
• 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: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A plasma processing system is provided that includes a chamber having a lower electrode coupled to a substrate support and an upper electrode coupled to ground. The plasma processing system having a plasma processing volume that is defined between the upper electrode and the lower electrode. A direct current (DC) to direct current (DC) converter is provided to receive at an input a DC voltage input and supply at an output an amplified DC voltage signal that includes a radio frequency (RF) component. The DC voltage input follows a pulsing pattern that is digitally programmable. The output of the DC to DC convertor is connected to the lower electrode of the chamber. A controller is interfaced with the DC to DC converter to set the pulsing pattern. In one example, the DC to DC converter uses one of a bipolar or non-bipolar DC voltage supply and a RF generator is driven by a DC voltage supply. The RF generator is configured to produce a frequency ripple that defines the RF component.

Claims

1. A plasma processing system, comprising,

a chamber having a lower electrode coupled to a substrate support and an upper electrode coupled to ground, a plasma processing volume is defined between the upper electrode and the lower electrode;

a direct current (DC) to direct current (DC) converter configured to receive at an input a DC voltage input and supply at an output an amplified DC voltage signal that includes a radio frequency (RF) component, the DC voltage input follows a pulsing pattern that is digitally programmable, the output of the DC to DC convertor is connected to the lower electrode of the chamber; and

a controller being interfaced with the DC to DC converter to set the pulsing pattern.

2. The plasma processing system of claim 1, wherein the DC to DC converter includes,

a DC voltage supply, and

a RF generator that is driven by the bipolar DC voltage supply, the RF generator producing a frequency of the RF component.

3. The plasma processing system of claim 2, wherein the DC to DC converter includes,

a resonant circuit that is configured to multiply the DC input voltage;

and

a rectifier circuit that receives the multiplied DC input voltage and the RF component to produce the amplified DC voltage signal that includes the RF component.

4. The plasma processing system of claim 3, further comprising,

a ripple control being interfaced with the controller, the ripple control configured to dynamically adjust the rectifier circuit to modify an amplitude of the frequency component.

5. The plasma processing system of claim 4, wherein the dynamic adjustment of the rectifier circuit enables settings of higher or lower amplitudes during each active pulse of the pulsing pattern.

6. The plasma processing system of claim 5, wherein the active pulse is one of a positive pulse of the amplified DC voltage signal or a negative pulse of the amplified DC voltage signal.

7. The plasma processing system of claim 1, wherein the RF component is supplied to a positive pulse of the amplified DC voltage signal or a negative pulse of the amplified DC voltage signal, and wherein no RF component is supplied during an off pulse of the amplified DC voltage signal.

8. The plasma processing system of claim 1, wherein the controller is coupled to a power control that provides the pulsing pattern, wherein the pulse pattern is digitally programmable to set one or more of voltage amplitude of the DC voltage input, a polarity of the DC voltage input, a rise and decay time of the DC voltage input, a width and delay of the DC voltage input, or combination of two or more thereof.

9. The plasma processing system of claim 1, wherein a process recipe is configured to set a programming for the pulse pattern, the programming being applied by the controller by digital programming to the DC to DC converter.

10. The plasma processing system of claim 2, wherein the voltage supply and RF generator include field effect transistors (FETs) that are driven by a gate driver and supplied the DC voltage input.

11. The plasma processing system of claim 3, wherein the resonant circuit is defined from resistive values, inductive values, and capacitive values, which define a quality factor Q, the quality factor Q providing an amplification for the amplified DC voltage signal.

12. The plasma processing system of claim 3, wherein the rectifier circuit defines at least part of a diode bridge.

13. The plasma processing system of claim 12, wherein circuits of the diode bridge being adjustable in response to a ripple control signal, the ripple control signal acting to adjust an amplitude of the frequency component during a positive pulse of the pulsing pattern.

14. The plasma processing system of claim 9, wherein the programming for the pulse pattern defines a frequency of the DC voltage input and a frequency of the RF component.

15. The plasma processing system of claim 14, wherein the frequency of the DC voltage input is less than about 1 MHz, and the frequency of the RF component is selected from one of 2 MHz, 13.56 MHz, 27 MHz, 60 MHz, or 80 MHz.

16. The plasma processing system of claim 14, wherein the frequency of the DC voltage input is 400 KHz or less and the frequency of the RF component is selected from one of 2 MHz, 13.56 MHz, 27 MHz, 60 MHz, or 80 MHz, wherein the chamber is configured for producing a capacitively coupled plasma (CCP) source between the lower electrode and the upper electrode, the CCP source being used for etching a material from a substrate when disposed on the substrate support of the chamber.

17. The plasma processing system of claim 16, wherein the DC to DC converter is one of a plurality of DC to DC converters connected to the lower electrode, wherein each of the plurality of DC to DC converters is configured to produce an amount of power and the plurality of DC to DC converters are combined to produce a sum of the amount of power from the plurality of DC to DC converters.

18. The plasma processing system of claim 16, wherein the pulsing pattern is selected from one of (i) an alternating positive and negative pulse, (ii) a positive pulse, an off period, and a negative pulse, (iii), a positive pulse, an off period, and a negative pulse, wherein a magnitude of the positive pulse and the negative pulse vary, (iv) a positive pulse, an off period, and a positive pulse, (v) a positive pulse, an adjustable off period, and another positive pulse and then repeat, (vi), a varying width positive or negative pulse that repeats, (vii), a positive predefined pulse width with a predefined pulse amplitude, followed by an off period, and then a repeat of the positive predefined pulse width with the predefined pulse amplitude;

(viii) a negative predefined pulse width with a predefined pulse amplitude, followed by an off period, and then a repeat of the negative predefined pulse width with the predefined pulse amplitude;

or (ix) a positive pulse having a predefined amplitude and width, followed by an off period or a negative pulse having a predefined amplitude and width, or (x) a combination of two or more thereof.

19. A plasma processing system, comprising,

a chamber having a lower electrode coupled to a substrate support and an upper electrode coupled to ground, a plasma processing volume is defined between the upper electrode and the lower electrode;

a first direct current (DC) to direct current (DC) converter configured to receive at an input a positive DC voltage input and supply at an output a positive amplified DC voltage signal that includes a radio frequency (RF) component, the positive DC voltage input follows a pulsing pattern that is digitally programmable, the output of the DC to DC convertor is connected to the lower electrode of the chamber;

a second direct current (DC) to direct current (DC) converter configured to receive at an input a negative DC voltage input and supply at an output a negative amplified DC voltage signal that includes a radio frequency (RF) component, the negative DC voltage input follows a pulsing pattern that is digitally programmable, the output of the DC to DC convertor is connected to the lower electrode of the chamber;

a controller being interfaced with the first and second DC to DC converters to set the pulsing pattern, wherein positive pulses of the pulsing pattern are provided by the first DC to DC converter and negative pulses of the pulsing pattern are provided by the second DC to DC converter.

20. The plasma processing system of claim 19, wherein each of the first and second DC to DC converters includes,

a DC voltage supply, and

a RF generator that is driven by the DC voltage supply, the RF generator producing a frequency of the RF component;

a resonant circuit that is configured to multiply the positive or negative DC input voltages; and

a rectifier circuit that receives the multiplied positive or negative DC input voltages and the RF component to produce the amplified positive or negative DC voltage signals that includes the RF component.

21. The plasma processing system of claim 20, further comprising,

a ripple control being interfaced with the controller, the ripple control configured to dynamically adjust the rectifier circuit of the first DC to DC converter to modify an amplitude of the frequency component.

22. The plasma processing system of claim 21, wherein the dynamic adjustment of the rectifier circuit enables settings of higher or lower amplitudes during each active pulse of the pulsing pattern.

23. The plasma processing system of claim 19, wherein the frequency of the positive and negative DC voltage input is 400 KHz or less and the frequency of the RF component is selected from one of 2 MHz, 13.56 MHz, 27 MHz, 60 MHz, or 80 MHz, wherein the chamber is configured for producing a capacitively coupled plasma (CCP) source between the lower electrode and the upper electrode, the CCP source being used for etching a material from a substrate when disposed on the substrate support of the chamber.

24. The plasma processing system of claim 19, wherein the pulsing pattern is selected from one of (i) an alternating positive and negative pulse, (ii) a positive pulse, an off period, and a negative pulse, (iii), a positive pulse, an off period, and a negative pulse, wherein a magnitude of the positive pulse and the negative pulse vary, (iv) a positive pulse, an off period, and a positive pulse, (v) a positive pulse, an adjustable off period, and another positive pulse and then repeat, (vi), a varying width positive or negative pulse that repeats, (vii), a positive predefined pulse width with a predefined pulse amplitude, followed by an off period, and then a repeat of the positive predefined pulse width with the predefined pulse amplitude;

(viii) a negative predefined pulse width with a predefined pulse amplitude, followed by an off period, and then a repeat of the negative predefined pulse width with the predefined pulse amplitude;

or (ix) a positive pulse having a predefined amplitude and width, followed by an off period or a negative pulse having a predefined amplitude and width, or (x) a combination of two or more thereof.

25. A method for processing a substrate using a capacitively coupled plasma (CCP) chamber driven by a DC to DC converter, comprising,

providing the chamber having a lower electrode coupled to a substrate support and an upper electrode coupled to ground, a plasma processing volume is defined between the upper electrode and the lower electrode;

providing a direct current (DC) voltage input based on a pulsing pattern, the pulsing pattern being defined by a digital program;

generating a radio frequency (RF) component using the DC input voltage;

amplifying the DC input voltage that includes the RF component; and

rectifying the RF component to produce an amplified DC voltage signal that includes the RF component, the amplified DC voltage signal that includes the RF component being supplied to the lower electrode of the chamber;

wherein the pulsing pattern that is defined by the digital program defines a frequency of the amplified DC voltage signal and a frequency of the RF component, the frequency of the amplified DC voltage defines positive or negative pulses, and pulse widths and amplitudes of the positive or negative pulses.

26. The method of claim 25, wherein the frequency of the DC voltage input is 400 KHz or less and the frequency of the RF component is selected from one of 2 MHz, 13.56 MHz, 27 MHz, 60 MHz, or 80 MHz, the CCP chamber used for etching a material from a substrate when disposed on the substrate support of the chamber.

27. The method of claim 25, further comprising,

providing a ripple control to dynamically adjust an amplitude of the RF component during a positive pulse of the pulsing pattern.

28. The method of claim 27, wherein the dynamic adjustment of the amplitude occurs during one or more phases of the positive pulse of the pulsing pattern.

29. The method of claim 25, wherein digital program that defines the pulse pattern set one or more of voltage amplitude of the DC voltage input, a polarity of the DC voltage input, a rise and decay time of the DC voltage input, a width and delay of the DC voltage input, or combination of two or more thereof.

30. The method of claim 29, wherein the pulsing pattern is selected from one of (i) an alternating positive and negative pulse, (ii) a positive pulse, an off period, and a negative pulse, (iii), a positive pulse, an off period, and a negative pulse, wherein a magnitude of the positive pulse and the negative pulse vary, (iv) a positive pulse, an off period, and a positive pulse, (v) a positive pulse, an adjustable off period, and another positive pulse and then repeat, (vi), a varying width positive or negative pulse that repeats, (vii), a positive predefined pulse width with a predefined pulse amplitude, followed by an off period, and then a repeat of the positive predefined pulse width with the predefined pulse amplitude;

(viii) a negative predefined pulse width with a predefined pulse amplitude, followed by an off period, and then a repeat of the negative predefined pulse width with the predefined pulse amplitude;

or (ix) a positive pulse having a predefined amplitude and width, followed by an off period or a negative pulse having a predefined amplitude and width, or (x) a combination of two or more thereof.