Methods and systems for monitoring state of plasma chamber

• US 20080278721A1
• Filed: 05/07/2008
• Published: 11/13/2008
• Est. Priority Date: 05/10/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Yong-Jin, Bai, Keun-Hee
• Granted Patent: US 7,705,973 B2
• Time in Patent Office: Days
• US Class Current: 356/311
• CPC Class Codes: G01J 3/443 Emission spectrometry
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32972 Spectral analysis

Abstract

Provided are methods and systems for monitoring a state of a plasma chamber. In the method, an optical characteristic of plasma generated in a plasma chamber including a window is measured in a predetermined measurement wavelength band. A process status index (PSI) is extracted from the measured optical characteristic. A state of the plasma chamber is evaluated by analyzing the extracted PSI. The optical characteristic of the plasma is measured in the predetermined measurement wavelength band in which a transmittance of light passing through the window is substantially independent of a wavelength of the light.

Claims

1. A method of monitoring a plasma chamber, comprising:

measuring an optical characteristic of plasma in a predetermined measurement wavelength band, the plasma being generated in the plasma chamber including a window;

extracting a process status index (PSI) from the measured optical characteristic; and

evaluating a state of the plasma chamber by analyzing the extracted PSI,

wherein the optical characteristic of the plasma is measured in the predetermined measurement wavelength band in which a transmittance of light passing through the window is substantially independent of a wavelength of the light.

2. The method of claim 1, wherein the optical characteristic of the plasma is measured in the predetermined measurement wavelength band in which a transmittance of light passing through the window varies in a range from about 1% to about 20% according to a wavelength of the light.

3. The method of claim 1, wherein the measuring of the optical characteristic comprises measuring light emitted from the plasma chamber, the light having a wavelength in a range from about 900 nm to about 1700 nm.

4. The method of claim 1, wherein the measuring of the optical characteristic comprises measuring a spectral characteristic of light emitted from the plasma chamber in a range of wavelength from about 600 nm to about 3000 nm.

5. The method of claim 1, wherein the predetermined measurement wavelength band is a band in which a transmittance variation of light passing through the window is substantially independent of a thickness of a by-product deposited on the window.

6. The method of claim 1, wherein the extracting of the PSI comprises performing an inner product of data of the optical characteristic and wavelength-weight data, wherein the wavelength-weight data are obtained by principal component analysis (PCA) or multi-way principal component analysis (MPCA).

7. The method of claim 6, wherein the extracting of the PSI further comprises normalizing intensity values of light measured in the predetermined measurement wavelength band based on an intensity value of light measured at a predetermined reference wavelength, prior to the performing of the inner product.

8. The method of claim 1, wherein the evaluating of the state of the plasma chamber comprises comparing the PSI with PSI trend data to provide information about a variation trend of the PSI with respect to time.

9. The method of claim 8, wherein the evaluating of the state of the plasma chamber further comprises transmitting a signal to an operator to inform the operator of a process error when a difference between the PSI and the PSI trend data is equal to or greater than a predetermined critical value.

10. The method of claim 9, wherein the evaluating of the state of the plasma chamber comprises disregarding a variation of the PSI caused by an intended process condition change by evaluating the variation of the PSI using condition-result data providing information about a relationship between process condition changes and variations of the PSI.

11. A system for monitoring a plasma chamber, comprising:

a measurement unit configured to measure light emitted from the plasma chamber through a window of the plasma chamber in a predetermined measurement wavelength band;

a process status index (PSI) extraction part configured to extract a PSI from an optical characteristic of the light; and

a status decision part configured to evaluate a state of the plasma chamber by analyzing the extracted PSI,

wherein the predetermined measurement wavelength band is a band in which a transmittance of light passing through the window is substantially independent of a wavelength of the light.

12. The system of claim 11, wherein the predetermined measurement wavelength band is a band in which a transmittance of light passing through the window varies in a range from about 1% to about 20% according to a wavelength of the light.

13. The system of claim 12, wherein the predetermined measurement wavelength band ranges from about 900 nm to about 1700 nm.

14. The system of claim 11, wherein the predetermined measurement wavelength band ranges from about 600 nm to about 3000 nm.

15. The system of claim 11, wherein the predetermined measurement wavelength band is a band in which a transmittance variation of light passing through the window is substantially independent of a thickness of a by-product deposited on the window.

16. The system of claim 11, wherein the PSI extraction part comprises a first processing part configured to convert intensity values of light measured in the predetermined measurement wavelength band into ratios to an intensity value of light measured at a predetermined reference wavelength.

17. The system of claim 16, wherein the PSI extraction part further comprises a second processing unit configured to calculate an inner product of wavelength-weight data and intensity values of light measured in the measurement wavelength band, wherein the wavelength-weight data are data obtained by principal component analysis (PCA) or multi-way principal component analysis (MPCA) for assigning different weights to the measured intensity values according to wavelength.

18. The system of claim 11, wherein the status decision part is configured to evaluate the state of the plasma chamber by comparing the PSI with PSI trend data providing information about a variation trend of the PSI with respect to time.

19. The system of claim 18, further comprising a user interface configured to transmit a signal to an operator to inform the operator of a process error when a difference between the PSI and the PSI trend data is equal to or greater than a predetermined critical value.

20. The system of claim 19, wherein the status decision part is configured to disregard a variation of the PSI caused by an intended process condition change by evaluating the variation of the PSI using condition-result data providing information about a relationship between process condition changes and variations of the PSI.