Leakage Current Improvement of Doped and Bilayer High-k for MIM Capacitor

Abstract

High-k dielectrics like Ta 2 O 5 , TiO 2 etc. should overcome high leakage current due to the low energy band-gap property for applying to the future DRAM device below 50 nm design rule beyond. Various techniques including metal doping and bi-layer scheme were studied to improve the leakage current of I-V characteristics. The leakage current of Dy or Zr doped TiO 2 could be improved depending on the doping concentration. Nb doping in Ta 2 O 5 could increase the dielectric constant within the appropriate level of leakage current at the operation voltage. Bi-layer scheme of high-k dielectrics like HfO 2 -TiO 2 or ZrO 2 -TiO 2 also applied to reduce the leakage current with the high work function Ru electrode. Combination of high work function Ru as a top electrode with the bottom TiN electrode could reduce the leakage current by increasing band offset at the interface between the highk and the electrode.

Study of Metal–Dielectric Interface for Improving Electrical Properties and Reliability of DRAM Capacitor

“…The present study covers not only high-k defects but also the role of the interface between the high-k dielectric and the metal electrodes. The excellent electrical performance of TiN-insulator-TiN (TIT) capacitors has already been demonstrated; [5][6][7] however, some problems have been observed, such as an abnormal current density increase at a negative biasing voltage in stress-induced leakage current (SILC) measurements, as shown in Figure 1a. This degradation of current density could be explained using the hole-induced breakdown model.…”