ABSTRACT
Without the ability to store information for later use, the flexibility of semiconductors is massively constrained. As a result, memory circuit design is of significant focus, and a variety of both circuit design approaches and materials research have been applied to the problem in the search for ever-improving density and access time. The flexibility associated with nonvolatile memory has historically been traded against performance, resulting in a robust demand for both volatile and nonvolatile memory technologies. To achieve high density, digital memory components are constructed from CMOS FET devices as opposed to bipolar device structures. The basis of any memory technology is the storage cell itself. The cell typically represents the vast percentage of silicon area in memory chips as well as in embedded memory macros, and the supporting peripheral circuitry is constructed to match the dimensions and shape of the cell array. The cell structure varies with the priorities applied to specific applications, and the reasoning behind each structure will be discussed along with the various types of memories.
