Extraction of the coupling coefficients for the top-floating-gate (TFG) flash EEPROM cell

A novel measurement technique utilising a new test structure is applied to the existing subthreshold methodology to extract coupling coefficients of the Top-Floating-Gate (TFG) cell. The TFG cell is unique in structure and operation in comparison with current NVM devices. It is designed with the FG surrounding the CG which greatly enhances the gate coupling ratio (/spl alpha//sub cg/) allowing a small area cell and avoiding the use of expensive z-direction extensions unlike the industry standard stacked-gate approach. This work quantifies this benefit for the area efficient TFG cell design.