Ferroelectricity Enhancement in Hf0.5Zr0.5O2 Based Tri-Layer Capacitors at Low-Temperature (350 °C) Annealing Process

The use of additional dielectric (DE) layers such as Al2O3, ZrO2, HfO2and Ta2O5with Hf0.5Zr0.5O2(HZO) ferroelectric (FE) layer, namely bi-layer systems are drawing much attention in the recent past due to enhanced FE properties and their applications in memory technology. However, HZO based tri-layer capacitors with various DE layers are not yet reported. The present paper demonstrates the enhanced FE properties of MFM tri- layer capacitors were found at low temperature (350 °C) using rapid thermal annealing (RTA) process. Various tri-layer capacitors were fabricated by changing top dielectric layers such as TiO2, ZrO2and SiO2(thickness of 10Å) while keeping FE HZO (100Å) and bottom HfO2DE layer (10Å) as constant and traditional P-E curves for all those tri-layer (DE/FE/DE) capacitors were observed. Among all the tri-layer capacitors, highest remanent polarization ( Pr~ 16.6 μC/cm2) was observed for the TiO2top DE at 350 °C. The addition of top DE layers induced strain in the FE film due to their different thermal expansion coefficients and as a resulting in enhancing o-phase. The demonstration of excellent ferroelectric property by the as fabricated metal-ferroelectric-metal (MFM) capacitors with crystallization temperature as low as 350 °C can be of significant importance in sensor and display applications.