CHARGE DECAY MEASUREMENT SYSTEMS AND METHODS

摘要

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. 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.

主权项

1. A system for characterizing a sample, the system comprising:
a first optical path configured to propagate an interrogating optical beam to the sample, the interrogating beam comprising a plurality of optical pulses, two consecutive pulses of the interrogating beam being spaced apart by a period (T), the period (T) corresponding to a repetition rate of the interrogating optical beam, said interrogating optical beam generating second harmonic generated light from the sample; an optical pump source outputting pump radiation; a detector configured to sample intensities of the generated second harmonic light at at least two temporally separated sample times, the two sample times occurring after charging the sample at a sample site by optically pumping; a controllable optical delay system configured to introduce a variable time delay (Δ) between at least one pulse from the interrogating beam and a reference time with respect to said charging the sample, the variable time delay Δ being shorter than the period (T) of the pulses from the interrogating beam, said controllable optical delay system configured to vary and control the duration of the time delay; and a processing and control module configured to obtain a characteristic of the sample based on intensities of said second harmonic generated light at the at least two sample times.