Etch stage measurement system

• US 8,173,451 B1
• Filed: 02/16/2011
• Issued: 05/08/2012
• Est. Priority Date: 02/16/2011
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Tian, Xinkang, Madriaga, Manuel
• Primary Examiner(s): Ahmadi, Mohsen
• Application Number:
  US13/028,960
• Time in Patent Office: 447 Days
• Field of Search: 257/E21.002, 257/E21.521, 257/E21.528, 257/E21.529
• US Class Current: 438/14
• CPC Class Codes: H01J 37/32917 Plasma diagnostics
• CPC Class Codes: H01J 37/32963 End-point detection

Abstract

Provided is a system for measuring an etch stage of an etch process involving one or more layers in a substrate, the etch stage measurement system configured to meet two or more etch stage measurement objectives. The system includes an etch process tool, the etch process tool having an etch chamber, a controller, and process parameters. The etch process tool is coupled to two or more optical metrology devices and at least one etch sensor device measuring an etch process parameter with high correlation to the etch stage. The processor is coupled to the etch process tool and is configured to extract an etch measurement value using a correlation of etch stage measurements to actual etch stage data and etch stage measurement obtained from the two or more metrology devices and the at least one etch process sensor device.

Claims

1. A system for measuring etch stage of an etch process of one or more layers on a substrate, the etch stage measurement configured to meet two or more etch stage measurement objectives, the system comprising:

an etch process tool configured to etch the one or more layers on the substrate, the etch process tool having an etch chamber, a controller, and one or more etch process parameters;

a first optical metrology device coupled to the etch process tool, the first optical metrology device configured to measure electromagnetic energy from the etch chamber;

a second optical metrology device coupled to the etch process tool, the second optical metrology device configured to illuminate the substrate in one or more sites and measure the diffraction signals from the one or more sites; and

a processor coupled to the etch process tool, the first optical metrology device, and the second optical metrology device, the processor configured to develop a correlation algorithm of the etch stage measurements to actual etch stage data, extract an etch measurement value using etch stage measurements from the first and second optical metrology devices and the correlation of measured electromagnetic energy from the first and second optical metrology devices to actual etch stage data, if calculated two or more etch stage measurement objectives compared to a set two or more etch stage measurement objectives are not met, modify first and second optical metrology devices, refine the correlation algorithm, and/or enhance the etch stage measurement by adjusting for noise in the measured electromagnetic energy, and iterate developing the correlation algorithm, extracting the etch measurement value, comparing the calculated two or more etch stage measurement objectives to the set two or more etch stage measurement, and modifying the first and/or the second optical metrology devices, refining the correlation algorithm, and/or enhancing the etch stage measurement by adjusting for noise in the measured electromagnetic energy objectives until the two or more etch stage measurement objectives are met,

wherein refining the correlation algorithm comprises using non-linear functional relationships between the electromagnetic energy measurements and the actual etch stage measurement data,

wherein the non-linear functional relationships include arbitrary functions, composite functions, and least squares fit solutions wherein least squares fit can include nonlinear fitting methods, searching parameter space methods, grid search methods, gradient search methods, expansion methods, and Marquardt methods.

2. The system of claim 1 wherein the two or more etch stage measurement objectives comprise an accuracy objective and a measurement and extraction time (MAET) objective.

3. The system of claim 1 wherein the two or more etch stage measurement objectives include an accuracy objective of 0.95 or better and a MAET objective of 6 milliseconds or less.

4. The system of claim 1 wherein the first optical metrology device includes a spectrometer disposed to measure the intensity of light from the etch chamber.

5. The system of claim 1 wherein the second optical metrology device includes at least one interferometer or reflectometer disposed above the etch chamber so as to allow transmission of an illumination beam and detection of a diffraction beam using a viewport.

6. The system of claim 1 wherein the second optical metrology device includes a plurality of interferometers or reflectometers, the interferometers or reflectometers disposed above the etch chamber so as to allow transmission of a plurality of illumination beams and detection of a plurality of diffraction beams.

7. The system of claim 6 wherein the second optical metrology device includes 5 to 9 interferometers or reflectometers.

8. The system of claim 6 wherein the plurality of illumination beams includes a spectroscopic beam with wavelengths in a range of 120 to 190 nanometers.

9. The system of claim 6 wherein the plurality of illumination beams includes a spectroscopic beam with wavelengths in a range of 170 to 190 nanometers or 120-1000 nanometers.

10. The system of claim 6 wherein the plurality of illumination beams includes a monochromatic beam with a wavelength in a range of 120 to 1000 nanometers.

11. The system of claim 6 wherein angle of incidence of the plurality of illumination beams to the substrate is from 1 to 10 degrees or substantially 0 degree.

12. The system of claim 1 wherein the extracted etch measurement value is percent completion of the etch process.

13. The system of claim 1 wherein the two or more etch stage measurement objectives include accuracy of 0.95 or better, a MAET objective of 6 milliseconds or less, and repeatability coefficients of two or more measurements of 0.95 or better.

14. The system of claim 1 wherein the extracted etch measurement value is the depth of the etched layer or the percent completion of the etch process according to a recipe of the etch process.

15. The system of claim 1 wherein modifying the selected two or more optical metrology devices comprises adjusting optical components of the selected two or more optical metrology devices.

16. The system of claim 1 wherein modifying the selected two or more optical metrology devices comprises replacing optical components of the selected two or more optical metrology devices or installing a new optical metrology device.

17. A system for measuring etch stage of an etch process of one or more layers on a substrate, the etch stage measurement configured to meet two or more etch stage measurement objectives, the system comprising:

an etch process tool configured to etch the one or more layers on the substrate, the etch process tool having an etch chamber, a controller, and one or more process parameters;

a first optical metrology device coupled to the etch process tool, the first optical metrology device configured to measure electromagnetic energy from the etch chamber;

a second optical metrology device coupled to the etch process tool, the second optical metrology device configured to illuminate the substrate in one or more sites and measure the diffraction signals from the one or more sites;

an etch sensor device coupled to the etch process tool, the etch sensor device configured to measure a process parameter with high correlation to the etch process and

a processor coupled to the etch process tool, the first optical metrology device, and the second optical metrology device, the processor configured to develop a correlation algorithm of the measured electromagnetic energy from the first and second optical metrology devices and the measured process parameter from the etch sensor device to actual etch stage data, extract an etch measurement value using electromagnetic energy measurements from the first and second optical metrology devices and the correlation of etch stage measurements to actual etch stage data, if calculated two or more etch stage measurement objectives compared to a set two or more etch stage measurement objectives are not met, modify first and second optical metrology devices, refine the correlation algorithm, and/or enhance the etch stage measurements by adjusting for noise in the measured electromagnetic energy, and iterate developing the correlation algorithm, extracting the etch measurement value, comparing the calculated two or more etch stage measurement objectives to the set two or more etch stage measurement, and modifying the first and second optical metrology devices, refining the correlation algorithm, and/or enhancing the etch stage measurements by adjusting for noise in the measured electromagnetic energy objectives until the two or more etch stage measurement objectives are met,

wherein the first optical metrology device includes a spectrometer disposed to measure the intensity of light from the etch chamber; and

the second optical metrology device includes a plurality of interferometers or reflectometers, the interferometers or reflectometers disposed above the etch chamber so as to allow transmission of a plurality of illumination beams and detection of a plurality of diffraction beams using two or more spectrometers.