Triple-Level Cell FeRAM With Wake-Up Free HfO 2 /ZrO 2 Superlattice Using Bilayer ALD Temperature Stacks

A bilayer superlattice (SL) Hf_xZr_1-xO₂ (HZO) stack is developed to combine the high endurance of low-temperature ALD (LTD) with the strong polarization benefits of high-temperature ALD (HTD). The optimized 5-nm HTD-SL/5-nm LTD-SL (HLTD) configuration demonstrates wake-up-free switching and suppressed fatigue. The resulting FeCAPs enable 3-bit/cell functionality with eight well-separated and stable polarization states sustained beyond 10⁸ cycles. These findings indicate that the proposed bilayer SL-HZO architecture holds strong potential for high-density embedded FeRAM applications.