Method and apparatus for improved plasma processing uniformity

• US 7,164,236 B2
• Filed: 03/05/2004
• Issued: 01/16/2007
• Est. Priority Date: 08/08/2000
• Status: Expired due to Term

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Tsukamoto, Yuji, Mitrovic, Andrej S., Strang, Eric J., Parsons, Richard, Quon, Bill H., Sirkis, Murray D.
• Primary Examiner(s): Lee; Wilson
• Application Number:
  US10/793,253
• Publication Number:
  US 20040168770A1
• Time in Patent Office: 1,047 Days
• Field of Search: 118/723.E, 118/723.MP, 118/723.AN, 118/723.I, 118/682, 204/298.08, 204/298.34, 204/192.12, 315/111.01, 315/111.81, 315/111.91, 156/643.1, 156/345.37, 156/345.53, 156/345.28, 156/345.44
• US Class Current: 315/111.01
• CPC Class Codes: H01J 37/32009 Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources plasma generation in general H05H1/24
• 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 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32532 Electrodes
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

A method and apparatus for generating and controlling a plasma (130) formed in a capacitively coupled plasma system (100) having a plasma electrode (140) and a bias electrode in the form of a workpiece support member (170), wherein the plasma electrode is unitary and has multiple regions (R_i) defined by a plurality of RF power feed lines (156) and the RF power delivered thereto. The electrode regions may also be defined as electrode segments (420) separated by insulators (426). A set of process parameters A={n, τ_i, Φ_i, P_i, S; L_i} is defined; wherein n is the number of RF feed lines connected to the electrode upper surface at locations L_i, τ_i is the on-time of the RF power for the i^th RF feed line, Φ_i is the phase of the i^th RF feed line relative to a select one of the other RF feed lines, P_i is the RF power delivered to the electrode through the i^th RF feed line at location L_i, and S is the sequencing of RF power to the electrode through the RF feed lines. One or more of these parameters are adjusted so that operation of the plasma system results in a workpiece (176) being processed with a desired amount or degree of process uniformity.

Claims

1. A method of determining a set of optimum plasma process parameters A*={n*, τ

_i*, Φ

_i*, P_i*, S*;

L_i*} for plasma processing, with a high degree of uniformity, a workpiece in a plasma reactor chamber having an electrode with an upper surface as part of a plasma reactor system, wherein n is the number of RF feed lines connected to the electrode upper surface at locations L_i, τ

_i is the on-time of the RF power for the i^th RF feed line, Φ

_i is the phase of the i^th RF feed line relative to a select one of the other RF feed lines, P_i is the RF power delivered to the electrode to location L_i through the i^th RF feed line, and S is the sequencing of RF power to the electrode through the RF feed lines, the method comprising the steps of;

a) setting initial values for process parameters n, τ

_i, Φ

_i, P_i, and S; and

b) processing one or more workpieces while varying one or more of said process parameters to determine the optimized set of process parameters A*={n*, τ

_i*, Φ

_i*, P_i*, S*} that achieve a process non-uniformity less than a predetermined standard, including use of at least one of a linear or a non-linear processing model as a basis for varying at least one of the process parameters.

2. A method according to claim 1, wherein said step b) includes the steps of:

i) forming a first plasma within the reactor chamber having characteristics corresponding to said process parameters and processing a first workpiece for a predetermined process time;

ii) measuring the workpiece process uniformity; and

iii) comparing the workpiece process uniformity to a predetermined standard.

3. A method according to claim 2, wherein said step b) further includes the step of:

iv) reducing the workpiece process non-uniformity by changing at least one of said process parameters and repeating said steps i) through iii) using one of said first workpiece and a workpiece other than said first workpiece, until the workpiece process non-uniformity is less than said predetermined standard.

4. A method according to claim 1, wherein in said steps a) and b), the locations L_i of the RF feed lines are parameters in the set A of process parameters that are varied.

5. A method according to claim 1, wherein the initial process parameter values are determined with the assistance of computer modeling.

6. A method according to claim 1, wherein said step b) includes use of a linear processing model as a basis for varying at least one of the process parameters.

7. A method according to claim 1, wherein said step b) includes use of a non-linear processing model as a basis for varying at least one of the process parameters.

8. A method according to claim 1, wherein said step b) includes providing RF power P_i to a plurality of electrode segments in a multi-segment electrode by multiplexing RF power via RF power multiplexing.

9. A method according to claim 8, wherein said RF power multiplexing is accomplished by programming a control system electrically connected to a plurality of RF power supplies and electronically controlling the activation of the RF power supplies.

10. A method according to claim 1, wherein said step b) involves providing RF power P_i to a unitary electrode via RF power multiplexing.

11. A method of processing a workpiece to be processed according to claim 1, further including the steps, after said step b), of:

c) providing the workpiece to be processed in the reactor chamber;

d) forming an optimized plasma with the process chamber using the set of optimized process parameters determined in said step b); and

e) processing the workpiece to be processed with the optimized plasma.

12. A method of determining a set of optimum plasma process parameters A*={n*, τ

_i*, Φ

_i*, P_i*, S*;

L_i*} for plasma processing, with a desired degree of uniformity, a workpiece in a plasma reactor chamber having an electrode with an upper surface as part of a plasma reactor system, wherein n is the number of RF feed lines connected to the electrode upper surface at locations L_i, τ

_i is the on-time of the RF power for the i^th RF feed line, Φ

_i is the phase of the i^th RF feed line relative to a select one of the other RF feed lines, P_i is the RF power delivered to the electrode to location L_i through the i^th RF feed line, and S is the sequencing of RF power to the electrode through the RF feed lines, the method comprising the steps of;

a) setting initial values for process parameters n, τ

_i, Φ

_i, P_i, and S; and

b) processing one or more workpieces while varying one or more of said process parameters to determine the optimized set of process parameters A*={n*, τ

_i*, Φ

_i*, P_i*, S*} that achieve a desired process uniformity, including use of at least one of a linear or a non-linear processing model as a basis for varying at least one of the process parameters.

13. A method according to claim 12, wherein said step b) includes the steps of:

i) forming a first plasma within the reactor chamber having characteristics corresponding to said process parameters and processing a first workpiece for a predetermined process time;

ii) measuring the workpiece process uniformity; and

iii) comparing the workpiece process uniformity to a predetermined standard.

14. A method according to claim 12, wherein said step b) further includes the step of:

iv) reducing the workpiece process non-uniformity by changing at least one of said process parameters and repeating said steps i) through iii) using one of said first workpiece and a workpiece other than said first workpiece, until the workpiece process non-uniformity is less than said predetermined standard.

15. A method of processing a workpiece to be processed according to claim 12, further including the steps, after said step b), of:

c) providing the workpiece to be processed in the reactor chamber;

d) forming an optimized plasma with the process chamber using the set of optimized process parameters determined in said step b); and

e) processing the workpiece to be processed with the optimized plasma.