METHODS FOR AUTOMATICALLY CHARACTERIZING A PLASMA

• US 20090322342A1
• Filed: 06/02/2009
• Published: 12/31/2009
• Est. Priority Date: 06/26/2008
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Thorgrimsson, Christopher, Booth, Jean-Paul, Keil, Douglas
• Granted Patent: US 8,849,585 B2
• Time in Patent Office: Days
• US Class Current: 324/464
• CPC Class Codes: H01J 2237/244 Detection characterized by the detecting means
• CPC Class Codes: H01J 2237/24564 Measurements of electric or magnetic variables, e.g. voltage, current, frequency
• CPC Class Codes: H01J 2237/327 Arrangements for generating the plasma
• 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 37/32926 Software, data control or modelling
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32954 Electron temperature measurement
• CPC Class Codes: H01L 21/263 with high-energy radiation H01L21/261 takes precedence

Abstract

A method for automatically characterizing plasma during substrate processing is provided. The method includes collecting a set of process data, which includes at least data about current and voltage. The method also includes identifying a relevancy range for the set of process data, wherein the relevancy range includes a subset of the set of process data. The method further includes determining a set of seed values. The method yet also includes employing the relevancy range and the set of seed values to perform curve-fitting, wherein the curve-fitting enables the plasma to be automatically characterized.

Claims

1. A method for automatically characterizing plasma during substrate processing, comprising:

collecting a set of process data, said set of process data including at least data about current and voltage;

identifying a relevancy range for said set of process data, wherein said relevancy range including a subset of said set of process data;

determining a set of seed values; and

employing said relevancy range and said set of seed values to perform curve-fitting, wherein said curve-fitting enables said plasma to be automatically characterized.

2. The method of claim 1 wherein said relevancy range for said set of process data is identified for said set of process data collected after each radio frequency (RF) charge.

3. The method of claim 2 wherein said identifying said relevancy range includes at least one of

calculating a peak of a first derivative of said set of process data, and

determining a percentage decay point, said percentage decay point representing a level below an original data value, wherein said relevancy range is between said original data value and said percentage decay point.

4. The method of claim 3 wherein said identifying, said relevancy range further includes identifying an inflection point, wherein said relevancy range is represented by a range between said original data value and said inflection point, said inflection point being a first derivative of said current values between said percentage decay point and a second decay point, said second decay point being between said original data value and said percentage decay point.

5. The method of claim 4 wherein said set of seed values includes at least one of a slope, an electron temperature, an ion saturation value, and a floating voltage potential.

6. The method of claim 5 wherein said determining said set of seed values includes determining an ion saturation interval, wherein said ion saturation interval pertains to an interval from said original data value to said second decay point.

7. The method of claim 6 wherein said slope is determined by performing a linear regression of said ion saturation interval.

8. The method of claim 7 wherein said ion saturation value is determined by averaging data values within said ion saturation interval.

9. The method of claim 8 wherein said electron temperature is determined by taking a first derivative of data collected at said inflection point.

10. The method of claim 9 wherein said floating voltage potential is determined by averaging voltage data collected from an initial floating voltage potential point to a data point before a second RF charge.

11. An article of manufacture comprising a program storage medium having computer readable code embodied therein, said computer readable code being configured for automatically characterizing plasma during substrate processing, comprising:

code for collecting a set of process data, said set of process data including at least data about current and voltage;

code for identifying a relevancy range for said set of process data, wherein said relevancy range including a subset of said set of process data;

code for determining a set of seed values; and

code for employing said relevancy range and said set of seed values to perform curve-fitting, wherein said curve-fitting enables said plasma to be automatically characterized.

12. The article of manufacture of claim 11 wherein said relevancy range for said set of process data is identified for said set of process data collected after each radio frequency (RF) charge.

13. The article of manufacture of claim 12 wherein said code for identifying said relevancy range includes at least one of

code for calculating a peak of a first derivative of said set of process data, and

code for determining a percentage decay point, said percentage decay point represents a level below an original data value, wherein said relevancy range is between said original data value and said percentage decay point.

14. The article of manufacture of claim 13 wherein said code for identifying said relevancy range further includes code for identifying an inflection point, wherein said relevancy range is represented by a range between said original data value and said inflection point, said inflection point being a first derivative of said current values between said percentage decay point and a second decay point, said second decay point being between said original data value and said percentage decay point.

15. The article of manufacture of claim 14 wherein said set of seed values includes at least one of a slope, an electron temperature, an ion saturation value, and a floating voltage potential.

16. The article of manufacture of claim 15 wherein said code for determining said set of seed values includes code for determining an ion saturation interval, wherein said ion saturation interval refers to an interval from said original data value to said second decay point.

17. The article of manufacture of claim 16 wherein code for determining said slope includes code for performing a linear regression of said ion saturation interval.

18. The article of manufacture of claim 17 wherein code for determining said ion saturation value includes code for averaging data values within said ion saturation interval.

19. The article of manufacture of claim 18 wherein code for determining said electron temperature includes code for taking a first derivative of data collected at said inflection point.

20. The article of manufacture of claim 19 wherein code for determining said floating voltage potential includes code for averaging voltage data collected from an initial floating voltage potential point to a data point before a second RF charge.