Patent ReferencesShadow ram cell having a shallow trench eeprom Method of making shadow RAM cell having a shallow trench EEPROM Three-dimensional direct-write EEPROM arrays and fabrication methods Non-volatile random access memory cell constructed of silicon carbide Process for forming a polysilicon electrode in a trench Low voltage EEPROM/NVRAM transistors and making method Method of making trench EPROM simultaneously with forming a DRAM cell Patent #: 5930619 InventorApplicationNo. 394093 filed on 09/13/1999US Classes:438/259, Including forming gate electrode in trench or recess in substrate257/E21.693, For vertical channel (EPO)257/E27.103, Electrically programmable ROM (EPO)438/270, Gate electrode in trench or recess in semiconductor substrate438/589Recessed into semiconductor substrateExaminersPrimary: Phan, TrongAttorney, Agent or FirmInternational ClassH01L 021/824.7AbstractA non-volatile random access memory (NVRAM) cell and method of fabrication thereof. Pairs of NVRAM cells, each including three FETs stacked in a NAND-like structure are formed vertically in silicon pillars. Source devices at the bottom of the pillar selectively provide ground to one of the cells. A floating gate extends upward from the source device's gate line. A control gate plate extending between adjacent pillars selectively provides a programming voltage to the control gate. Both the source gate and the control gate are capacitively coupled through silicon rich oxide to the floating gate. Polysilicon plugs between silicon pillars are word line gates for cells in adjacent pillars. A diffusion at the top of each pillar is a bit line contact for both cells at the pillar. Each pair of cells on a pillar are on a common bit line and a common word line. The word line, control gate and source gate line select individual cells in the pair. | |