Integration of Split Word Line Ferroelectric Memories Using Etch Stopping Layers and Multi-Layer Etching Technology

概要

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Split word line ferroelectric random access memories (SAVE FeRAMs) were fabricated using etch stopping layers and multi-layer etching technology. As the SWL FeRAM does not use a common CP line, the operation speed can be enhanced and the decrease of remnant polarization of non-selected cell capacitors can be prevented in write/read operation. The cell capacitors were composed of Pt electrodes and the sol-get derived Pb(Zr,Ti)O_3 films. The ferroelectric capacitors were formed by etching a metal-ferroelectric-metal (MFM) and a metal-ferroelectric (MF) using Ru and Ti masks with a good etch selectivity, which could simplify the etching process. The etch stopping layers of RuO_2 and TiO_2 were introduced to solve the over-etching problem of BPSG. The degradation of the ferroelectric capacitors due to etching process and interlayer dielectric (ILD) deposition process was almost recovered by annealing in oxygen. Memory operation was confirmed in the 2T/2C SWL FeRAM with the capacitor area down to 16 μm^2.
社団法人電子情報通信学会の論文
1999-07-23