Integration of Novel Capacitor Structure for High Density FeRAM With Barrier Metal TiAlN and (Bi,La)₄Ti₃O₁₂

Abstract

16M 1T1C ferroelectric random access memory was successfully integrated by newly proposed scheme named Recessed Open Barrier (ROB) structure with planar Pt/BLT/Pt/IrOx/Ir stacked capacitor. In conventional barrier metal scheme which bottom electrode was stacked, oxygen diffused through the bottom electrode interface formed during MTP structure integration, and oxidized the edge of barrier metal resulting compressive stress. The failure was accelerated by free oxygen diffusion as the stress built up to make the bottom electrode pop-up. In this paper, the barrier metal TiAlN was recessed and refilled by ALD Al₂O₃ after bottom electrode patterning. By this novel structure, oxidation resistance was greatly improved, because oxygen diffusion path to BM was much longer than conventional scheme. The contact resistance of storage node was below 10 kΩ/plug after all the thermal budget relevant to BLT capacitor.

Keywords:

• FeRAM
• barrier metal
• recessed open barrier
• alumina