5.1 Å EOT and low leakage TiN/Al2O3/Hf0.5Zr0.5O2/Al2O3/TiN heterostructure for DRAM capacitor

Further scaling of dynamic random-access memory (DRAM) faces critical challenges because of the lack of materials with both high dielectric constant and low leakage. In this work, engineering Hf1-xZrxO2 (HZO) films to the morphotropic phase boundary (MPB) and inserting Al2O3 interface layers with a wide bandgap are utilized to overcome this bottleneck. By tuning Zr composition and the woken-up process, the ratio of tetragonal and orthorhombic phases is manipulated to achieve the desired high dielectric constant MPB state. On this basis, Al2O3 ultrathin layers are inserted to further enhance the dielectric constant as well as reduce the leakage current. As a result, a high dielectric constant of similar to 46.7 (equivalent oxide thickness similar to 5.1A degrees) and low leakage current density (<10(-7) A/cm(2) at +/- 0.5 V) are achieved in TiN/Al2O3 (0.2 nm)/Hf0.5Zr0.5O2 (5.6 nm)/Al2O3 (0.3 nm)/TiN capacitors. Furthermore, long dielectric breakdown time of the heterostructure confirms its application potential. These results are useful for developing next generation DRAM capacitor devices. Published under an exclusive license by AIP Publishing.

Automated summary

By engineering Hf1-xZrxO2 (HZO) films and inserting Al2O3 interface layers, the challenge of obtaining both high dielectric constant and low leakage for dynamic random-access memory (DRAM) is overcome. The results show that the TiN/Al2O3 (0.2 nm)/Hf0.5Zr0.5O2 (5.6 nm)/Al2O3 (0.3 nm)/TiN capacitors achieve a high dielectric constant of about 46.7 and low leakage current density, with the added benefit of long dielectric breakdown time, making them suitable for next generation DRAM capacitor devices.