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IBM Journal of Research and Development  
Volume 21, Number 5, Page 402 (1977)
Nontopical Issue
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Analysis of the Merged Charge Memory (MCM) Cell

by H.-S. Lee
This paper describes a new MOS dynamic RAM (Random-Access Memory) cell which utilizes a merged surface charge transistor structure. The merged charge memory (MCM) cell uses a polysilicon electrode as both a bit sense line and common plate for a column of storage capacitors. The MCM structure is self-aligned, contactless and free of closely spaced p-n junctions. Its spatial density approaches the conceptual limit of the intersection formed by two orthogonal lines or 4W2 where W is the minimum geometry feature. The cell area utilization efficiency is improved because of this simplicity. Preliminary experimental results and ASTAP simulations based on the charge control equivalent circuit for a dynamic potential well are described. Implications for chip design constraints are discussed, and the advantages and limitations of MCM are highlighted where appropriate.
Related Subjects: Circuit and device technology; Memory (computer) design and technology; Physics, solid state