PLASMA PROCESSING APPARATUS, PLASMA PROCESSING METHOD AND PLASMA PROCESSING ANALYSIS METHOD

• US 20160225681A1
• Filed: 08/12/2015
• Published: 08/04/2016
• Est. Priority Date: 01/30/2015
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: ASAKURA, Ryoji, TAMAKI, Kenji, SHIRAISHI, Daisuke, KAGOSHIMA, Akira, INOUE, Satomi
• Granted Patent: US 10,408,762 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 21/68 using high frequency electric fields
• CPC Class Codes: H01J 37/32926 Software, data control or modelling
• CPC Class Codes: H01J 37/32972 Spectral analysis
• CPC Class Codes: H01J 37/3299 Feedback systems
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring

Abstract

A plasma processing apparatus, plasma processing method, and plasma processing analysis method in which a suitable combination of wavelength, time interval, and etching condition parameter for control to change etching conditions is determined among wavelengths, time intervals, and changeable parameters for spectroscopic measurement data in order to ensure stable etching conditions. Specifically, a regression equation which represents the correlation between emission intensity and etching result at a wavelength and a time interval is obtained for each of two or more combinations of wavelength, time interval, and etching condition parameter. Furthermore, for each of the combinations, the amount of change is calculated from the regression equation when the value set for the etching condition parameter is changed. Among the combinations, the combination for which the amount of change is the smallest is determined as the combination of wavelength, time interval, and changed etching condition parameter to be used for control.

Claims

1. A plasma processing apparatus which performs plasma processing on a specimen under APC as control to suppress fluctuations in plasma processing by feedback control or feedforward control and has an analysis unit to find a suitable combination for the APC of emission wavelength, time interval for the emission wavelength, and a parameter for the plasma processing,

wherein the analysis unit performs:

obtaining a first regression equation representing correlation between emission intensity and plasma processing result from temporal change data of the plasma processing;

obtaining a second regression equation representing correlation between emission intensity and plasma processing result by changing the parameter; and

finding a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the APC based on a coefficient of correlation of the first regression equation, and a difference between a gradient of the first regression equation and a gradient of the second regression equation.

2. The plasma processing apparatus according to claim 1, wherein the parameter is provided in plurality.

3. The plasma processing apparatus according to claim 1, wherein the analysis unit further calculates a weighted sum of residual of the first regression equation and residual of the second regression equation and finds a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the APC, based on the coefficient of correlation, the difference, and the weighted sum.

4. The plasma processing apparatus according to claim 1, wherein the analysis unit calculates a difference correction value, using estimation error of the second regression equation as square average of residual of the second regression equation divided by dispersion on a horizontal axis for the difference, and finds a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the APC.

5. A plasma processing apparatus which performs plasma processing on a specimen under APC as control to suppress fluctuations in plasma processing by feedback control or feedforward control and is connected with an analysis unit to find a suitable combination for the APC of emission wavelength, time interval for the emission wavelength, and a parameter for the plasma processing,

wherein the analysis unit performs:

obtaining a first regression equation representing correlation between emission intensity and plasma processing result, from temporal change data of the plasma processing;

obtaining a second regression equation representing correlation between emission intensity and plasma processing result is obtained by changing the parameter; and

finding a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing suitable for the APC based on a coefficient of correlation of the first regression equation, and a difference between a gradient of the first regression equation and a gradient of the second regression equation.

6. The plasma processing apparatus according to claim 5, wherein the parameter is provided in plurality.

7. The plasma processing apparatus according to claim 5, wherein the analysis unit further calculates a weighted sum of residual of the first regression equation and residual of the second regression equation and finds a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the APC, based on the coefficient of correlation, the difference, and the weighted sum.

8. The plasma processing apparatus according to claim 5, wherein the analysis unit calculates a difference correction value, using estimation error of the second regression equation as square average of residual of the second regression equation divided by dispersion on a horizontal axis for the difference, and finds a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the APC.

9. A plasma processing method using a plasma processing apparatus which performs plasma processing on a specimen under APC as control to suppress fluctuations in plasma processing by feedback control or feedforward control and has an analysis unit to find a suitable combination for the APC of emission wavelength, time interval for the emission wavelength, and a parameter for the plasma processing, the method comprising the steps of:

obtaining a first regression equation representing correlation between emission intensity and plasma processing result from temporal change data of the plasma processing by using the analysis unit;

obtaining a second regression equation representing correlation between emission intensity and plasma processing result by changing the parameter by using the analysis unit;

finding a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the APC, based on a coefficient of correlation of the first regression equation, and a difference between a gradient of the first regression equation and a gradient of the second regression equation by using the analysis unit; and

performing plasma processing by using the plasma processing apparatus on the specimen under the APC which uses the combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing found by the analysis unit.

10. An analysis unit which finds a combination of wavelength, time interval for the wavelength, and a parameter for plasma processing which is suitable for control to suppress fluctuations in the plasma processing by feedback control or feedforward control,

wherein a first regression equation representing correlation between emission intensity and plasma processing result is obtained from temporal change data of the plasma processing,

wherein a second regression equation representing correlation between emission intensity and plasma processing result is obtained by changing the parameter, and

wherein a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the control is found based on a coefficient of correlation of the first regression equation, and a difference between a gradient of the first regression equation and a gradient of the second regression equation.

11. An analysis method which finds a combination of wavelength, time interval for the wavelength, and a parameter for plasma processing which is suitable for control to suppress fluctuations in the plasma processing by feedback control or feedforward control, comprising the steps of:

obtaining a first regression equation representing correlation between emission intensity and plasma processing result from temporal change data of the plasma processing;

obtaining a second regression equation representing correlation between emission intensity and plasma processing result by changing the parameter; and

finding a combination of wavelength, time interval for the wavelength, and a parameter for the plasma processing which is suitable for the control, based on a coefficient of correlation of the first regression equation, and a difference between a gradient of the first regression equation and a gradient of the second regression equation.