Analysis of the merged charge memory (MCM) cell

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.

[1]  A.F. Tasch,et al.  The charge-coupled RAM cell concept , 1976, IEEE Transactions on Electron Devices.

[2]  R.A. Haken.  Supply charge isolation—A simple surface potential equilibration charge-injection technique for charge-coupled devices , 1976, IEEE Transactions on Electron Devices.

[3]  Carver A. Mead,et al.  Push clocks: a new approach to charge‐coupled devices clocking , 1973 .

[4]  Hwang Soo Lee,et al.  Merged charge memory (MCM)—A new random access cell , 1976 .

[5]  M. F. Tompsett,et al.  Charge Transfer Devices , 1972 .

[6]  William E. Engeler,et al.  Intracell charge-transfer structures for signal processing , 1974 .

[7]  William E. Engeler,et al.  A surface-charge random-access memory system , 1972 .

[8]  H. S. Lee.  An analysis of the threshold voltage for short-channel IGFET's , 1973 .

[9]  G. E. Smith,et al.  Charge coupled semiconductor devices , 1970, Bell Syst. Tech. J..

[10]  Carver A. Mead,et al.  Charge transfer in overlapping gate charge-coupled devices , 1973 .

[11]  M. Tompsett.  Surface potential equilibration method of setting charge in charge-coupled devices , 1975, IEEE Transactions on Electron Devices.

[12]  R.R. Troutman.  Hot electron emission from a semiconductor under low-level avalanche multiplication , 1976, 1976 International Electron Devices Meeting.

[13]  L. G. Heller,et al.  Charge-control method of charge-coupled device transfer analysis , 1972 .

[14]  L. G. Heller,et al.  High sensitivity charge-transfer sense amplifier , 1975 .

[15]  C. N. Berglund,et al.  Incomplete transfer in charge-transfer devices , 1973 .