Method of fabricating random access memory device

Abstract

A dynamic random access memory is fabricated on a monolithic chip of semiconductor material. The memory is formed of an array of memory cells controlled for reading and writing by word and bit lines which are selectively connected to the cells. Each cell is a single field effect transistor structure having improved electrical charge storage capability. The improved charge storage capability of each cell is provided by an electrical capacitance structure uniquely arranged and formed as an integral portion of the field effect transistor structure. The gate electrode of each field effect transistor structure is connected to a predetermined one of said word lines. The drain of each field effect transistor is connected to a predetermined one of said bit lines. The source of each field effect transistor structure is integrally connected to and forms a portion of the uniquely arranged electrical capacitance structure of the field effect transistor structure. The electrical capacitance or storage node structure of each cell has increased electrical charge storage capacity and may be considered as a single capacitor. The single (storage) capacitor of each cell is provided between the source of the field effect transistor, a source of reference potential (reference plane) and the monolithic semiconductor substrate on which the memory is fabricated. The arrangement of the memory cells, the structure and material of each of the memory cells, and a method of fabricating the entire memory is disclosed. Also disclosed is an improved field effect transistor structure and process for fabricating same. The process of fabrication, cell arrangement and the improved storage node of each memory cell, as structurally fabricated and uniquely arranged, provides a monolithic memory having improved density and operating characteristics.