Low Operation Voltage, High-Temperature Reliable, and High-Yield BEOL Integrated Hf₀.₅Zr₀.₅O₂ Ferroelectric Memory Arrays

Emerging embedded nonvolatile memory (eNVM) based on hafnium oxide ferroelectric materials has shown great advantages such as high reliability, high speed, good scalability, and CMOS process compatibility. Here, a 2T2C structure ferroelectric memory (FRAM) is proposed based on the 180-nm CMOS technology and a TiN/Hf <tex-math notation="LaTeX">0.5</tex-math> Zr <tex-math notation="LaTeX">0.5</tex-math> O <tex-math notation="LaTeX">₂</tex-math> /TiN ferroelectric capacitor. The device exhibits great ferroelectric properties with the remnant polarization (2P <tex-math notation="LaTeX">ᵣ)</tex-math> of 30 <tex-math notation="LaTeX">μ</tex-math> C/cm <tex-math notation="LaTeX">²</tex-math> under a low operation voltage of 2 V. Also, it shows great high-temperature endurance and retention properties, which has no obvious degradation after 10 <tex-math notation="LaTeX">¹⁰</tex-math> cycles pulses and 10 <tex-math notation="LaTeX">⁴</tex-math> s under 175 <tex-math notation="LaTeX">∘</tex-math> C. In addition, a 2-Mb capacity memory chip with 16 <tex-math notation="LaTeX">×</tex-math> 128 kb subarrays using the 2T2C structure and separated word lines (WLs) was fabricated. The wafer can maintain a high yield of 98.28% after baking for 30 h at 175 <tex-math notation="LaTeX">∘</tex-math> C, which shows great reliability in the chip level.