ABSTRACT
The basis entity in a semiconductor memory is a cell in which a bit of information is stored. Static random access memories (SRAM) employs six or four transistors in each cell and the dynamic RAM (DRAM) uses a single transistor, called access transistor, and a small value capacitor, called storage capacitor. Early-stage DRAM cell was a simple entity with a planar metal-oxide-semiconductor field-effect transistor and a planar capacitor fabricated side by side. Most of the early and middle-age advancements in DRAM fabrication were done on bulk silicon substrate. With the reduction in minimum feature size, cost of silicon on insulator technology became comparable to the bulk silicon technology, with the added advantage of lesser parasitic capacitance. Dramatic reduction in cell size and complexity was achieved in a one-transistor DRAM cell, though at the expense of certain cell properties. The sense amplifiers used with DRAMs are generally different from sense amplifiers used with SRAMs and ROMs.
