Memory mechanism in floating si‐gate tunnel injection mis structure

By analyzing the writing characteristics of the poly‐Si floating‐gate tunnel injection MIS as a nonvolatile memory device, the memory charge storage site and its density will become clear. A memory diode is fabricated in which the first oxide thickness ∼30Å, the undoped poly‐Si floating gate thickness ∼260Å and the second oxide thickness ∼260Å. Measurement of the flat‐band shift based on constant capacitance tracing method and measurement of the writing charge are conducted simultaneously. Results show that the writing charge centroid on the floating gate varies with the writing time. The memory charge storage sites are seen as the trap states in the poly‐Si so that the charge centroid shift is controlled by the charge‐discharge time constant of the traps. Also the trapping state density is estimated to be 8.3 × 1017 cm‐3.