FIELD-BIASED SECOND HARMONIC GENERATION METROLOGY
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.
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 coupled 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 .- 27 . (canceled)
28 . 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;
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.
29 . The system of claim 28 , 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
30 . The system of claim 29 , wherein said one or more coils is a single coil.
31 . The system of claim 29 , wherein said one or more coils comprises a plurality of coils.
32 . The system of claim 28 , 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.
33 . The system of claim 28 , 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.
34 . The system of claim 28 , further comprising a chuck, said one or more coils disposed in said chuck.
35 .- 46 . (canceled)
47 . 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 the 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.
48 . The method of claim 47 , wherein producing said voltage comprises using an capacitively coupled electrode disposed with respect to the sample and capacitively coupled to at least a portion of said sample.
49 . The method of claim 47 , said capacitively coupled electrode comprises a ring, disc or plate with an opening for said probing radiation to pass to said sample.
50 . The method of claim 47 , wherein producing said voltage comprises using a magnetic field to induce an electric field across at least a portion of the sample.
51 . The method of claims 50 , wherein said magnetic field comprises a changing magnetic field (dB/dt).
52 . The method of claim 47 , wherein using a magnetic field comprise applying a current through coils to generate a magnetic field.
53 .- 94 . (canceled)