SYSTEMS AND METHODS FOR CONTROLLING A VOLTAGE WAVEFORM AT A SUBSTRATE DURING PLASMA PROCESSING

• US 20170358431A1
• Filed: 06/08/2017
• Published: 12/14/2017
• Est. Priority Date: 06/13/2016
• Status: Active Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: DORF, LEONID, ROGERS, JAMES HUGH, LUERE, OLIVIER, KOH, TRAVIS, DHINDSA, RAJINDER, SRINIVASAN, SUNIL
• Application Number:
  US15/618,082
• Publication Number:
  US 20170358431A1
• Time in Patent Office: Days
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing
• CPC Class Codes: H01J 37/32706 Polarising the substrate
• CPC Class Codes: H01J 37/32715 Workpiece holder
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/3299 Feedback systems

Abstract

Systems and methods for controlling a voltage waveform at a substrate during plasma processing include applying a shaped pulse bias waveform to a substrate support, the substrate support including an electrostatic chuck, a chucking pole, a substrate support surface and an electrode separated from the substrate support surface by a layer of dielectric material. The systems and methods further include capturing a voltage representative of a voltage at a substrate positioned on the substrate support surface and iteratively adjusting the shaped pulse bias waveform based on the captured signal. In a plasma processing system a thickness and a composition of a layer of dielectric material separating the electrode and the substrate support surface can be selected such that a capacitance between the electrode and the substrate support surface is at least an order of magnitude greater than a capacitance between the substrate support surface and a plasma surface.

Claims

1. A method for controlling a voltage waveform at a substrate during plasma processing in a plasma processing chamber, comprising:

applying a shaped pulse bias waveform to a substrate support within the plasma processing chamber, the substrate support including an electrostatic chuck, a chucking pole, a substrate support surface and an electrode;

capturing a signal representative of a voltage at a substrate positioned on the substrate support surface; and

iteratively adjusting the shaped pulse bias waveform based on the captured signal.

2. The method of claim 1, comprising:

capturing the signal representative of a voltage at the substrate using a conductive lead in contact with at least a portion of the substrate.

3. The method of claim 1, wherein the substrate support includes a ring of conductive material disposed above the electrode which senses a signal representative of a voltage at the substrate and the signal representative of a voltage at the substrate is captured using at least one of a conductive lead in contact with at least a portion of the ring of conductive material or a coupling circuit proximate the ring of conductive material.

4. The method of claim 1, comprising:

capturing the signal representative of a voltage at the substrate using a coupling circuit proximate the substrate.

5. The method of claim 1, wherein the iteratively adjusting comprises evaluating the captured signal representative of the voltage at the substrate and generating, in response to the evaluation, a control signal to be applied to a bias supply to adjust the shaped pulse bias waveform to maintain the voltage at the substrate constant or within a tolerance of a predetermined voltage level.

6. The method of claim 1, comprising:

applying the shaped pulse bias waveform to the electrode of the substrate support.

7. The method of claim 1, comprising:

applying the shaped pulse bias waveform to the chucking pole.

8. A plasma processing system, comprising:

a substrate support defining a surface for supporting a substrate to be processed, the substrate support including an electrostatic chuck, a chucking pole, and an electrode;

a sensor capturing a signal representative of a voltage at a substrate positioned on the substrate support surface;

a bias supply providing a shaped pulse bias waveform to the substrate support; and

a controller receiving the captured signal from the sensor and generating a control signal to be communicated to the bias supply to adjust the shaped pulse bias waveform based on the captured signal.

9. The plasma processing system of claim 8, wherein the sensor comprises a conductive lead in contact with at least a portion of the substrate.

10. The plasma processing system of claim 8, wherein the sensor comprises a ring of conductive material disposed above the electrode.

11. The plasma processing system of claim 10, comprising a conductive lead in contact with at least a portion of the ring of conductive material.

12. The plasma processing system of claim 10, comprising a coupling circuit proximate the ring of conductive material to deliver the captured signal to the controller.

13. The plasma processing system of claim 8, wherein the sensor comprises a coupling circuit proximate the substrate.

14. The plasma processing system of claim 8, wherein the shaped pulse bias waveform is applied to the electrode of the substrate support.

15. The plasma processing system of claim 8, wherein the shaped pulse bias waveform is applied to the chucking pole of the substrate support.

16. A plasma processing system, comprising:

a substrate support, the substrate support including an electrostatic chuck, a chucking pole, and an electrode and defining a surface to support a substrate to be processed, wherein the electrode is separated from the substrate support surface by a layer of dielectric material;

a plasma, disposed above the substrate support surface; and

a shaped pulse bias waveform generator to apply a shaped pulse bias waveform to the electrode,

wherein a thickness and a composition of the layer of dielectric material is selected such that a capacitance of the dielectric layer between the electrode and the substrate support surface is at least an order of magnitude greater than a capacitance between the substrate support surface and the plasma.

17. The plasma processing system of claim 16, wherein the dielectric layer comprises aluminum nitride having a thickness of about three to five millimeters.

18. The plasma processing system of claim 16, wherein the shaped pulse bias waveform is applied to the electrode of the substrate support.

19. The plasma processing system of claim 16, wherein the shaped pulse bias waveform is applied to the chucking pole of the substrate support.

20. The plasma processing system of claim 16, comprising a coupling circuit for coupling the shaped pulse bias waveform and a clamping voltage to the substrate support.