Highly Stable Etch Stopper Technology for 0.25 μm 1 Transistor 1 Capacitor (1T1C) 32 Mega-Bit Ferroelectric Random Access Memory (FRAM)

概要

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Since current 32 Mb high-density ferroelectric random access memory (FRAM) shows very narrow sensing window, it is strongly desired to improve the sensing widow for generating a reliable high yield. In this paper, we propose a TiAlN oxygen stopping layer for enhancing the diffusion barrier layer, which makes it possible to reduce the bottom stack height from 180 nm to 90 nm, resulting in the increase of effective cell area and cell charge. In addition to the enhanced diffusion barrier, we developed a stable PE-SiN etch stopper for replacing Ir noble metal etch stopper that has strong stress variation and eventually deteriorates the cell charge distribution. By using TiAlN oxygen stopping layer and PE-SiN etch stopper, the 32 Mb FRAM device shows very wide sensing window of 100 fC, which guarantees a reliable high yield.
2003-04-15