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 inducing an electric field across at least a portion of 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;
an optical detector configured to detect second harmonic generated light from the sample;
processing electronics configured to determine a characteristic of the detected second harmonic generated light; and
a magnetic source configured to apply a magnetic field to said sample to induce an electric field across at least a portion of said sample by induction in addition to any electric field produced by said probing radiation.
2. The system of claim 1 , wherein said magnetic source comprises one or more coils and a source of current electrically connected to said one or more coils.
3. The system of claim 1 , wherein said magnetic source comprises a permanent magnet.
4. The system of claim 1 , wherein said magnetic source comprises an electro-magnet disposed in proximity to said sample to apply a magnetic field thereto.
5. The system of claim 4 , wherein said electro-magnet is configured to apply a changing magnetic field to said sample.
6. The system of claim 1 , wherein said probing radiation is synchronized with said electric field.
7. The system of claim 1 , wherein said processing electronics is configured for gating in synchronization with said electric field.
8. The system of claim 1 , wherein said electric field is varied.
9. The system of claim 1 , wherein said electric field is modulated.
10. The system of claim 1 , wherein said electric field is alternating.