Field-biased second harmonic generation metrology

• US 10,663,504 B2
• Filed: 10/31/2017
• Issued: 05/26/2020
• 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): Koval, Melissa J
• Assistant Examiner(s): McDonnough, Courtney G
• Application Number:
  US15/799,594
• Publication Number:
  US 20180217192A1
• Time in Patent Office: 938 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 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. Decay constants can be measured to provide information regarding the sample. Additionally, electric and/or magnetic field biases can be applied to the sample to provide additional information.

Claims

1. A system for optically interrogating a surface of a sample while applying a bias to said sample, said system comprising:

a first optical source configured to emit probing radiation, said first optical source disposed so as to direct said probing radiation onto said surface of said sample;

a first contact electrical probe configured to form electrical contact with said sample;

a second capacitively coupled probe configured to capacitively couple with said sample without touching said surface of said sample;

a power supply configured to apply said bias to said sample via said first contact electrical probe and said second capacitively coupled probe;

an optical detector configured to detect second harmonic generated light from the sample; and

processing electronics configured to determine a characteristic of the detected second harmonic generated light.

2. The system of claim 1, wherein said first contact electrical probe comprises a backside contact.

3. The system of claim 1, wherein said first contact electrical probe comprises a galvanic contact with a bulk or substrate layer of the sample.

4. The system of claim 1, wherein said first contact electrical probe comprises a conductive chuck.

5. The system of claim 1, wherein said sample comprises a wafer and said first contact electrical probe comprises a conductive chuck for holding said wafer.

6. The system of claim 1, wherein said second contact electrical probe comprises a ring, disc or plate.

7. The system of claim 1, wherein said second contact electrical probe is spaced apart from said sample by 1 to 2 mm.

8. The system of claim 1, wherein the second capacitively coupled probe is spaced apart from said surface of the sample by a gap.

9. A system for optically interrogating a surface of a sample while applying a magnetic field to said sample, said system comprising:

a first optical source configured to emit probing radiation, said first optical source disposed so as to direct said probing radiation onto said surface of said sample;

a magnetic field source disposed with respect to the sample to generate a magnetic field through the sample, wherein the generated magnetic field induces an electrical potential between two surfaces of the sample;

an optical detector configured to detect second harmonic generated light from the sample; and

processing electronics configured to determine a characteristic of the detected second harmonic generated light.

10. The system of claim 9, wherein said magnetic field source comprises one or more coils electrically connected to a power supply and disposed with respect to the sample such that application of a current through the coil generates a magnetic field through the sample.

11. The system of claim 10, wherein said one or more coils is a single coil.

12. The system of claim 10, wherein said one or more coils comprises a plurality of coils.

13. The system of claim 10, wherein said power supply comprises an AC power supply such that AC current is applied to said one or more coils thereby producing an alternating magnetic field through said sample.

14. The system of claim 10, wherein said power supply comprises an DC power supply such that DC current is applied to said one or more coils thereby producing a constant magnetic field through said sample.

15. The system of claim 10, further comprising a chuck, said one or more coils disposed in said chuck.

16. The system of claim 15, wherein the chuck comprises a surface parallel to the sample configured to support said sample thereon, and the one or more coils are oriented parallel to the surface of the chuck.

17. A method of optical interrogation of a sample having a top side and a bottom side, the method comprising:

applying probing radiation from a probing optical source to a surface of the sample;

producing a voltage across at least a portion of the sample without contacting the top side of the sample;

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

determining a characteristic of the detected Second Harmonic Generation (SHG) effect signal in the presence of said voltage.

18. The method of claim 17, wherein producing said voltage comprises using a capacitively coupled electrode disposed with respect to the sample and capacitively coupled to at least a portion of said sample.

19. The method of claim 18, wherein said capacitively coupled electrode comprises a ring, disc or plate with an opening for said probing radiation to pass to said sample.

20. The method of claim 17, wherein producing said voltage comprises using a magnetic field to induce an electric field across at least a portion of the sample.

21. The method of claim 20, wherein said magnetic field comprises a changing magnetic field (dB/dt).

22. The method of claim 20, wherein using a magnetic field comprise applying a current through coils to generate a magnetic field.

23. The method of claim 18, further comprising providing a gap between the capacitively coupled electrode and the top side of the sample.