Contact-free floating-gate memory array with silicided buried bitlines and with single-step-defined floating gates

摘要

A contact-free floating-gate non-volatile memory cell array and process with silicided NSAG bitlines and with source/drain regions buried beneath relatively thick silicon oxide. The bitlines have a relatively small resistance, eliminating the need for parallel metallic conductors with numerous bitline contacts. The array has relatively small bitline capacitance and may be constructed having relatively small dimensions. Isolation between bitlines is by thick field oxide. Wordlines may be formed from silicided polycrystalline or other material with low resistivity. Coupling of programming and erasing voltages to the floating gate is improved by extending the gates over the thick field oxide and perhaps by using an insulator with relatively high dielectric constant between the control gate and the floating gate. The sides of the floating gates are defined with a single patterning step. The resulting structure is a dense cross-point array of programmable memory cells.