Impact of Cation Vacancies on Leakage Current on TiN/ZrO2/TiN Capacitors Studied by Positron Annihilation

TiN/ZrO2/TiN capacitors were characterized using XRD, STEM, EDX, and monoenergetic positron beams. For an as-deposited ZrO2 layer, an interlayer was formed in the layer. After post-deposition annealing at 550°C, the width of the interlayer expanded. The major vacancy-type defects in the ZrO2 layer were determined to be a Zr-vacancy coupled with oxygen vacancies by the positron annihilation technique. After annealing, the size of these vacancies increased. The presence of the cation vacancies and their complexes in the ZrO2 layer suggests that not only oxygen vacancies but also such defects play a role in the defect formation of the ZrO2 layer and affect its electrical properties.