RF-biased capacitively-coupled electrostatic (RFB-CCE) probe arrangement for characterizing a film in a plasma processing chamber

• US 8,164,353 B2
• Filed: 07/07/2009
• Issued: 04/24/2012
• Est. Priority Date: 07/07/2008
• Status: Expired due to Fees

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Booth, Jean-Paul, Albarede, Luc, Keil, Douglas, Kim, Jung
• Primary Examiner(s): NGUYEN, HOAI AN D
• Application Number:
  US12/498,955
• Publication Number:
  US 20100007362A1
• Time in Patent Office: 1,022 Days
• Field of Search: 324/686, 324/658, 324/649, 324/600, 324/715, 324/713, 324/522, 324/76.69, 324/555, 324/76.11, 324/762.01, 702/1, 702/57, 702/64, 702/127, 340/660, 340/664, 361/79, 361/86, 361/87
• US Class Current: 324/686
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part

Abstract

A method for characterizing deposited film on a substrate within a processing chamber during processing is provided. The method includes determining voltage-current characteristic for a probe head when measuring capacitor is set at a first capacitance value. The method also includes applying RF train to the probe head when measuring capacitor is set at a capacitance value greater than first capacitance value. The method further includes providing an initial resistance value and an initial capacitance value for the deposited film. The method yet also includes employing initial resistance value, initial capacitance value, and voltage-current characteristic to generate simulated voltage-time curve. The method yet further includes determining measured voltage-time curve, which represents potential drop across the deposited film for one RF train. The method more over includes comparing the two curves. If the difference is less than predefined threshold, employ initial resistance value and initial capacitance for characterizing the deposited film.

Claims

1. A method for characterizing a deposited film on a substrate within a processing chamber of a plasma processing system during substrate processing, comprising:

determining a voltage-current characteristic for a probe head, wherein a measuring capacitor is set at a first capacitance value;

applying a radio frequency (RF) train to said probe head, thereby causing said measuring capacitor to be charged, wherein said measuring capacitor is set at a second capacitance value, said second capacitance value being greater than said first capacitance value;

providing an initial resistance value for said deposited film and an initial capacitance value for said deposited film;

employing said initial resistance value, said initial capacitance value, and said voltage-current characteristic to generate a first simulated voltage-time curve;

determining a first measured voltage-time curve, said first measured voltage-time curve representing a potential drop across said deposited film for one RF train; and

comparing said first simulated voltage-time curve to said first measured voltage-time curve, wherein if a difference between said first simulated voltage-time curve and said first measured voltage-time curve is less than a predefined threshold, employing said initial resistance value and said initial capacitance for characterizing said deposited film.

2. The method of claim 1 further including

if said difference between said first simulated voltage-time curve and said first measured voltage-time curve is greater than said predefined threshold, applying a non-linear least square curve algorithm to generate a second resistance value and a second capacitance value;

employing said second resistance value, said second capacitance value, and said voltage-current characteristic to generate a second simulated voltage-time curve; and

determining a second measured voltage-time curve; and

comparing said second simulated voltage-time curve to said second measured voltage-time curve, wherein

if a difference between said second simulated voltage-time curve and said second measured voltage-time curve is less than said predefined threshold, employing said second resistance value and said second capacitance for characterizing said deposited film, and

if said difference between said second simulated voltage-time curve and said second measured voltage-time curve is greater than said predefined threshold, applying said non-linear least square curve algorithm to generate a third resistance value and a third capacitance value.

3. The method of claim 2 further including calculating a simulated voltage-time curve and a measured voltage-time curve and comparing said simulated voltage-time curve against said measured voltage-time curve until a difference between said simulated voltage-time curve and said measured voltage-time curve is less than said predefined threshold.

4. The method of claim 3 wherein said voltage-current characteristic is generated by

measuring potential across said measuring capacitor to determine a potential rate of change, and

measuring current across said measuring capacitor to determine a rate of capacitor current discharge.

5. The method of claim 4 wherein said initial resistance value and said initial capacitance value are empirically calculated.

6. The method of claim 4 wherein said initial resistance value and said initial capacitance value are theoretically determined.

7. The method of claim 4 wherein a resistance value of said deposited film is related to chemical composition of said deposited film, said resistance value is a function of film resistivity, distance, and cross-area of said probe head.

8. The method of claim 4 wherein a capacitance value of said deposited film is related to at least thickness of said deposited film and relative dielectric permittivity, said capacitance value being a function of permittivity of free space, relative permittivity of film dielectric material, surface area of said probe head, and film thickness.

9. The method of claim 1 wherein said measuring capacitor is a switchable capacitor arrangement with multiple capacitors, wherein each capacitor of said multiple capacitors has a different capacitance value.

10. An article of manufacture comprising a program storage medium having computer readable code embodied therein, said computer readable code being configured for characterizing a deposited film on a substrate within a processing chamber of a plasma processing system during substrate processing, comprising:

code for determining a voltage-current characteristic for a probe head, wherein a measuring capacitor is set at a first capacitance value;

code for applying a radio frequency (RF) train to said probe head, thereby causing said measuring capacitor to be charged, wherein said measuring capacitor is set at a second capacitance value, said second capacitance value being greater than said first capacitance value;

code for providing an initial resistance value for said deposited film and an initial capacitance value for said deposited film;

code for employing said initial resistance value, said initial capacitance value, and said voltage-current characteristic to generate a first simulated voltage-time curve;

code for determining a first measured voltage-time curve, said first measured voltage-time curve representing a potential drop across said deposited film for one RF train; and

code for comparing said first simulated voltage-time curve to said first measured voltage-time curve, wherein if a difference between said first simulated voltage-time curve and said first measured voltage-time curve is less than a predefined threshold, code for employing said initial resistance value and said initial capacitance for characterizing said deposited film.

11. The article of manufacture of claim 10 further including

if said difference between said first simulated voltage-time curve and said first measured voltage-time curve is greater than said predefined threshold, code for applying a non-linear-least square curve algorithm to generate a second resistance value and a second capacitance value;

code for employing said second resistance value, said second capacitance value, and said voltage-current characteristic to generate a second simulated voltage-time curve; and

code for determining a second measured voltage-time curve; and

code for comparing said second simulated voltage-time curve to said second measured voltage-time curve, wherein

if a difference between said second simulated voltage-time curve and said second measured voltage-time curve is less than said predefined threshold, code for employing said second resistance value and said second capacitance for characterizing said deposited film, and

if said difference between said second simulated voltage-time curve and said second measured voltage-time curve is greater than said predefined threshold, code for applying said non-linear least square curve algorithm to generate a third resistance value and a third capacitance value.

12. The article of manufacture of claim 11 further including code for calculating a simulated voltage-time curve and a measured voltage-time curve and code for comparing said simulated voltage-time curve against said measured voltage-time curve until a difference between said simulated voltage-rime curve and said measured voltage-time curve is less than said predefined threshold.

13. The article of manufacture of claim 12 wherein said voltage-current characteristic is generated by

code for measuring potential across said measuring capacitor to determine a potential rate of change, and

code for measuring current across said measuring capacitor to determine a rate of capacitor current discharge.

14. The article of manufacture of claim 13 wherein said initial resistance value and said initial capacitance value are empirically calculated.

15. The article of manufacture of claim 13 wherein a resistance value of said deposited film is related to chemical composition of said deposited film, said resistance value is a function of film resistivity, distance, and cross-area of said probe head.

16. The article of manufacture of claim 13 wherein a capacitance value of said deposited film is related to at least thickness of said deposited film and relative dielectric permittivity, said capacitance value being a function of permittivity of free space, relative permittivity of film dielectric material, surface area of said probe head, and film thickness.

17. The article of manufacture of claim 10 wherein said measuring capacitor is a switchable capacitor arrangement with multiple capacitors, wherein each capacitor of said multiple capacitors has a different capacitance value.

18. An arrangement for characterizing a deposited film within a processing chamber of a plasma processing system during substrate processing, comprising:

a probe arrangement, wherein said probe arrangement is configured for at least measuring one plasma processing parameter, said probe arrangement including

a plasma-facing sensor made of a conductive material, and

a measuring capacitor configured to be switched between two or more values, wherein said plasma-facing sensor is coupled to a first plate of said measuring capacitor;

a radio frequency (RF) voltage source, said RF voltage source being coupled to a second plate of said measuring capacitor, wherein said RF voltage source is configured to provide RF oscillation trains to said plasma-facing sensor;

a resistor-capacitor circuit, wherein said resistor-capacitor circuit includes a resistor in parallel with a capacitor;

a current measurement device, said current measurement device being disposed in series between said measuring capacitor and said RF voltage source, wherein said current measurement device is configured to detect said measuring capacitor current discharge rate;

a voltage measurement device disposed between said first plate of said measuring capacitor and ground, wherein said voltage measurement device is configured for measuring potential of said plasma-facing sensor; and

a signal processor, wherein said signal processor is configured for analyzing said current discharge rate and said potential of said plasma-facing sensor to determine a voltage-current characteristic for said plasma-facing sensor.

19. The arrangement of claim 18 wherein said plasma-facing sensor is disposed on a chamber wall of said processing chamber and is substantially co-planar with said chamber wall.

20. The arrangement of claim 18 wherein said plasma-facing sensor is a radio frequency-biased (RFB) capacitively-coupled electrostatic (CCE) probe head.