Characterization of vacancy-type defects in semiconductor device materials by means of positron annihilation

The principle of positron annihilation method is outlined. Positron annihilation method can detect, with good sensitivity, vacancy-type defects in crystalline and amorphous materials. It detects the defects using the phenomenon that the electron momentum distribution and electron density in vacancies are different from at interstitial sites. Detectable defect size is from about a single atom vacancy size to sub-nm, and it also can estimate the depth distribution of the voids. As the application of positron annihilation, following items are introduced: (1) detection of photoactive vacancy-type defects in gallium nitride deposited on a Si substrate, (2) detection of vacancy-type defects in the plating copper in plating copper wiring / low dielectric constant material structure, and (3) correlation between residual impurities and vacancy-type defects, and evaluation results of their annealing behavior. (A.O.)