A corrugated capacitor cell (CCC)

Abstract

A new MOS dynamic random access memory (dRAM) cell named "CCC" has been successfully developed based on a one-device cell concept. This CCC is characterized by an etched-moat storage-capacitor extended into the substrate, resulting in almost independent increase in storage capacitance C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</inf> of its cell size. A typical C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</inf> value of 60 fF has been obtained with 3 × 7 µm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> CCC having a 4-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. The CCC is discussed in terms of its capacitance characteristics, dRAM operation with unit 32-Kbit array, some limiting factor to its closer packing, and future considerations.