A new ultra high density 1F1R MLC flash contact RRAM

A new ultra high-density memory is firstly demonstrated by combining contact random access memory (CRRAM) with flash memory cell as a 1F1R structure. This study reports the first time of processing CRRAM in advanced 50nm flash memory process. The combination of CRRAM and flash cell to form a single Multi-Level Cell (MLC) memory directly doubles the storage capacity without area penalty. The TiON-based resistive film is sandwiched by a tiny tungsten contact plug as a top electrode and source n+ region as a bottom electrode. The new 1F1R MLC memory is successfully realized by two combined storage mechanisms: the contact resistive film switching between HRS and LRS states and the floating gate operating between high and low V_TH states. Besides, its excellent reliability of high endurance, stable data retention, and read and program disturb immunity further support this new 1F1R MLC Flash Contact RRAM to be a very promising candidate for high-density NVM applications beyond floating gate solutions.