Creating ion energy distribution functions (IEDF)

• US 10,685,807 B2
• Filed: 05/07/2019
• Issued: 06/16/2020
• Est. Priority Date: 12/12/2016
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Dorf, Leonid, Koh, Travis, Luere, Olivier, Joubert, Olivier, Kraus, Philip A., Dhindsa, Rajinder, Rogers, James
• Primary Examiner(s): Vanore, David A
• Application Number:
  US16/405,377
• Publication Number:
  US 20190259562A1
• Time in Patent Office: 406 Days
• Field of Search: 21912141, 21912143, 25049221, 438706, 438710, 438712, 438714, 438720
• CPC Class Codes: H01J 37/08 Ion sources; Ion guns
• CPC Class Codes: H01J 37/248 Components associated with high voltage supply means for measuring the high voltage per se G01R15/00
• CPC Class Codes: H01J 37/32577 Electrical connecting means
• CPC Class Codes: H01J 37/32706 Polarising the substrate
• CPC Class Codes: H01J 37/32715 Workpiece holder

Abstract

Systems and methods for creating arbitrarily-shaped ion energy distribution functions using shaped-pulse-bias. In an embodiment, a method includes applying a positive jump voltage to an electrode of a process chamber to neutralize a wafer surface, applying a negative jump voltage to the electrode to set a wafer voltage, and modulating the amplitude of the wafer voltage to produce a predetermined number of pulses to determine an ion energy distribution function. In another embodiment a method includes applying a positive jump voltage to an electrode of a process chamber to neutralize a wafer surface, applying a negative jump voltage to the electrode to set a wafer voltage, and applying a ramp voltage to the electrode that overcompensates for ion current on the wafer or applying a ramp voltage to the electrode that undercompensates for ion current on the wafer.

Claims

1. A method, comprising:

applying a negative jump voltage to an electrode of a process chamber to set a wafer voltage for a wafer;

modulating the wafer voltage at different amplitudes;

producing a relative number of pulses at each of the different amplitudes; and

determining a relative ion fraction at an ion energy corresponding to at least one of the different amplitudes based on a number of pulses produced at the at least one of the different amplitudes.

2. The method of claim 1, comprising:

applying a positive jump voltage to the electrode of the process chamber to neutralize a surface of the wafer.

3. The method of claim 2, wherein the positive jump voltage is applied to the electrode of the process chamber prior to applying the negative jump voltage.

4. The method of claim 1, wherein the modulation of the amplitude of the wafer voltage controls a feature profile of a resulting ion energy distribution function.

5. The method of claim 1, wherein the amplitude of the wafer voltage is modulated to create a desired ion energy distribution function.

6. The method of claim 5, wherein the desired ion energy distribution function is created to induce a specific bias voltage waveform on the wafer.

7. The method of claim 1, comprising:

modulating the wafer voltage at different points in time to create an ion energy distribution function having more than one energy peak.

8. The method of claim 7, wherein an ion fraction for each of the energy peaks is determined by a number of pulses produced during a respective modulation of the wafer voltage at the different points in time.

9. A method comprising:

applying a positive jump voltage to an electrode of a process chamber to neutralize a surface of a wafer;

applying a negative jump voltage to the electrode to set a wafer voltage for the wafer; and

applying a voltage ramp to the electrode that has a more negative slope than is required to maintain a constant voltage on the wafer.

10. The method of claim 9, wherein a minimum voltage and a maximum voltage of a current induced on the wafer determine a width of a resulting ion energy distribution function.

11. The method of claim 9, comprising:

adjusting a slope of the ramp voltage to create a desired ion energy distribution function.

12. The method of claim 11, wherein the desired ion energy distribution function is created to induce a specific bias voltage waveform on the wafer.

13. A method comprising:

applying a positive jump voltage to an electrode of a process chamber to neutralize a surface of a wafer;

applying a negative jump voltage to the electrode to set a wafer voltage for the wafer; and

applying a ramp voltage to the electrode that has a less negative slope than is required to maintain a constant voltage on the wafer.

14. The method of claim 13, wherein a minimum voltage and a maximum voltage of a current induced on the wafer determine a width of a resulting ion energy distribution function.

15. The method of claim 13, comprising:

adjusting a slope of the ramp voltage to create a desired ion energy distribution function.

16. The method of claim 15, wherein the desired ion energy distribution function is created to induce a specific bias voltage wave form on the wafer.