Randomness of channel dopant distribution in metal-oxide-semiconductor field-effect transistor (MOSFET) structures was analyzed by laserassisted atom probe tomography. Three-dimensional dopant distributions of boron and arsenic atoms in MOSFET channels which define the threshold voltage were obtained with nearly atomic scale resolution. In order to achieve highly statistical precision, about 130 million atoms were detected in the channel region. We found that the distribution of boron atoms was consistent with a random solid solution in a matrix. Meanwhile, the arsenic atom distribution is slightly deviated from the random distribution, implying the possibility of arsenic cluster formation.
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