A corrugated capacitor cell (CCC) for megabit dynamic MOS memories

Abstract

A new dRAM cell named "CCC" (Corrugated Capacitor Cell) has been successfully developed based on the one-device cell concept. This CCC is characterized by an etched-moat storage-capacitor extended into the substrate, resulting in an almost independent increase in storage capacitance without cell size enlargement. A typical value of 45 fF has been obtained with 4 × 8 µm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> CCC having a 2.5-µm deep moat and a capacitor insulator equivalent to 15 nm SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> in thickness. A signal of 200 mV is realized in 32 kbit dRAM operation with a folded-bit line arrangement having 128 bit identical CCC's. The CCC concept is promising for generations of 1 Mbit dRAM's and beyond.