Remarkably High Dielectric Constant and Capacitance Density by Ni/ZrO2/TiN Using Nanosecond Laser and Surface Plasma Effect.

Abstract

Rapid thermal annealing (RTA) has been widely used in semiconductor device processing. However, the rise time of RTA, limited to the millisecond (ms) range, is unsuitable for advanced nanometer-scale electronic devices. Using sub-energy bandgap (E_G) 532 nm ultra-fast 15 nanosecond (ns) pulsed laser annealing, a record-high dielectric constant (high-κ) of 67.8 and a capacitance density of 75 fF/μm² at -0.2 V were achieved in Ni/ZrO₂/TiN capacitors. According to heat source and diffusion equations, the surface temperature of TiN can reach as high as 870 °C at a laser energy density of 16.2 J/cm², effectively annealing the ZrO₂ material. These record-breaking results are enabled by a novel annealing method-the surface plasma effect generated on the TiN metal. This is because the 2.3 eV (532 nm) pulsed laser energy is significantly lower than the 5.0-5.8 eV energy bandgap (E_G) of ZrO₂, making it unabsorbable by the ZrO₂ dielectric. X-ray diffraction analysis reveals that the large κ value and capacitance density are attributed to the enhanced crystallinity of the cubic-phase ZrO₂, which is improved through laser annealing. This advancement is critical for monolithic three-dimensional device integration in the backend of advanced integrated circuits.