High performance metal–insulator–metal capacitors with atomic vapor deposited HfO2 dielectrics

Thin HfO2 films were grown as high-k dielectrics for Metal–Insulator–Metal applications by Atomic Vapor Deposition on 8 inch TiN/Si substrates using pure tetrakis(ethylmethylamido)hafnium precursor. Influence of deposition temperature (320–400 °C) and process pressure (2–10 mbar) on the structural and electrical properties of HfO2 was investigated. X-ray diffraction analysis showed that HfO2 layers, grown at 320 °C were amorphous, while at 400 °C the films crystallized in cubic phase. Electrical properties, such as capacitance density, capacitance–voltage linearity, dielectric constant, leakage current density and breakdown voltage are also affected by the deposition temperature. Finally, TiN/HfO2/TiN stacks, integrated in the Back-End-of-Line process, possess 3 times higher capacitance density compared to standard TiN/Si3N4/TiN capacitors. Good step coverage (> 90%) is achieved on structured wafers with aspect ratio of 2 when HfO2 layers are deposited at 320 °C and 4 mbar.