Pump and probe type second harmonic generation metrology

• US 10,613,131 B2
• Filed: 01/29/2018
• Issued: 04/07/2020
• Est. Priority Date: 04/17/2014
• Status: Active Grant

• Current Assignee: Femtometrix Inc
• Original Assignee: Femtometrix Inc
• Inventors: Koldiaev, Viktor, Kryger, Marc, Changala, John
• Primary Examiner(s): Ayub, Hina F
• Application Number:
  US15/882,433
• Publication Number:
  US 20180299497A1
• Time in Patent Office: 799 Days
• CPC Class Codes: G01N 21/636 using an arrangement of pump beam and probe beam; using the measurement of optical non-linear properties; non-linear optics per se G02F1/35
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 27/00 Investigating or analysing materials by the use of electric, electrochemical, or magnetic means G01N3/00 – G01N25/00 take precedence; measurement or testing of electric or magnetic variables or of electric or magnetic properties of materials G01R
• CPC Class Codes: G01R 29/24 Arrangements for measuring quantities of charge
• CPC Class Codes: G01R 31/2601 Apparatus or methods therefor G01R31/2607, G01R31/2642 take precedence
• CPC Class Codes: G01R 31/2656 using non-ionising electromagnetic radiation, e.g. optical radiation
• CPC Class Codes: G01R 31/2831 Testing of materials or semi-finished products, e.g. semiconductor wafers or substrates G01R31/318511 takes precedence; testing during manufacture H01L22/00
• CPC Class Codes: G01R 31/308 using non-ionising electromagnetic radiation, e.g. optical radiation investigating or analysing materials by the use of optical means G01N21/00; image analysis G06T7/00
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

Various approaches to can be used to interrogate a surface such as a surface of a layered semiconductor structure on a semiconductor wafer. Certain approaches employ Second Harmonic Generation and in some cases may utilize pump and probe radiation. Other approaches involve determining current flow from a sample illuminated with radiation.

Claims

1. A method of optical interrogation comprising:

applying pumping radiation across an entire semiconductor wafer using a pump optical source;

providing probing radiation to a first location on the wafer using a probe optical source;

raster scanning the probing radiation or the wafer;

providing probing radiation to a second location on the wafer using the probe optical source;

detecting a Second Harmonic Generation (SHG) effect signal at the first and second locations generated by at least one of the pumping radiation and the probing radiation using an optical detector; and

a) obtaining the SHG effect signal less than 10 seconds after applying at least one of the pumping radiation and the probing radiation at the first or second locations or b) varying a wavelength of the pumping radiation to detect a region wherein the SHG effect signal suddenly changes in slope to determine a threshold injection carrier energy.

2. The method of claim 1, further comprising applying the pumping radiation and the probing radiation with a variable time offset relative to one another to enable determination of one or more material parameters, the variable time offset being associated with energy of at least one of the probing radiation or the pumping radiation.

3. The method of claim 1, comprising:

a) obtaining the SHG effect signal within less than 10 seconds after applying at least one of;

the pumping radiation and the probing radiation, and b) applying the pumping and probing radiation with a variable time offset relative to one another to enable determination of material parameters not otherwise attainable with application of probing radiation only or pumping and probing radiation without the variable time offset.

4. The method of claim 1, comprising:

a) obtaining the SHG effect signal within less than 10 seconds after applying at least one of the pumping radiation and the probing radiation, b) applying the pumping and probing radiation with a variable time offset relative to one another to enable determination of material parameters, and c) varying a wavelength of the pumping radiation to detect a region wherein the SHG effect signal suddenly changes in slope to determine threshold injection carrier energy.

5. The method of claim 1, comprising:

a) obtaining the SHG effect signal within less than 10 seconds after applying at least one of;

the pumping radiation and the probing radiation and b) varying a wavelength of the pumping radiation to detect a region wherein the SHG effect signal suddenly changes in slope to determine threshold injection carrier energy.

6. The method of claim 1, comprising:

a) applying the pumping and probing radiation with a variable time offset relative to one another to enable determination of material parameters, and b) varying a wavelength of the pumping radiation to detect a region wherein the SHG effect signal suddenly changes in slope to determine threshold injection carrier energy.

7. The method of any of claims 1, wherein the SHG effect signal is obtained in less than 6 seconds after applying at least one of the pumping radiation and the probing radiation.

8. The method of any of claims 1, wherein the SHG effect signal is obtained in less than 1 second after applying at least one of the pumping radiation and the probing radiation.

9. The method of any of claims 1, wherein the SHG effect signal is obtained in less than 10 nanoseconds after applying at least one of the pumping radiation and the probing radiation.

10. The method of claim 1, wherein the pumping radiation has an average optical power greater than about 100 mW.

11. The method of claim 1, wherein the pumping radiation has an average optical power less than about 10 W.

12. The method of claim 1, wherein the pumping radiation has a wavelength between about 80 nm and about 1000 nm.

13. The method of claim 1, wherein the probing radiation has an average optical power less than about 150 mW.

14. The method of claim 1, wherein the probing radiation has a peak optical power greater than about 10 kW.

15. The method of claim 1, wherein the probing radiation has a peak optical power less than about 1 GW.

16. The method of claim 1, wherein the probing radiation has a wavelength between about 100 nm to 2000 nm.

17. The method of claim 1, wherein the pump optical source comprises a UV flash lamp.

18. The method of claim 1, wherein the pump optical source comprises a pulsed laser.

19. The method of claim 1, wherein the SHG effect signal is obtained less than 10 seconds after applying at least one of the pumping radiation and the probing radiation.

20. The method of claim 1, wherein the wavelength of the pumping radiation is varied to detect a region wherein the SHG effect signal suddenly changes in slope to the threshold injection carrier energy.

21. A method of optical interrogation comprising:

applying pumping radiation from a pump optical source across an entire semiconductor wafer;

applying probing radiation from a probing optical source to a first location on the wafer;

raster scanning the probing radiation or the wafer;

applying probing radiation from the probing optical source to a second location on the wafer;

detecting a Second Harmonic Generation (SHG) effect signal generated by at least one of the pumping radiation and the probing radiation at the first and second locations using an optical detector;

varying a wavelength of the pumping radiation; and

determining a characteristic of the detected Second Harmonic Generation (SHG) effect signal in the presence of at least one of the pumping and probing radiation.

22. A method of optical interrogation comprising:

applying pumping radiation energy from a pump optical source across an entire semiconductor wafer;

applying probing radiation energy from a probing optical source to a first location on the wafer;

raster scanning the probing radiation energy or the wafer;

applying probing radiation energy from the probing optical source to a second location on the wafer;

detecting a Second Harmonic Generation (SHG) effect signal at the first and second locations using an optical detector;

varying energy of the pump radiation; and

identifying an inflection point in the SHG effect signal associated with a threshold injection carrier energy.