Improvement of RRAM device performance through on-chip resistors

Abstract

Research in non-volatile memories (NVM) has intensified in the past few years due to the ever increasing demand for information storage and the near ubiquity of handheld electronics. Resistive memory is a leading contender in this NVM market due to its high endurance, random accessibility, scalability and low programming voltage. The addition of an external series resistor or imposing current compliance is often used to limit the current through RRAM devices and to prevent "over-programming" and stuck-at-one (SA1) errors. Here, we demonstrate that utilizing an external series resistor is not efficient in preventing over-programming and an on-chip resistor is more desirable. Poly-silicon bottom electrode based devices (with the poly-silicon electrode acting like an on-chip resistor) and metal bottom electrode devices were fabricated and tested. The presence of the on-chip resistor is shown to enhance the endurance of the RRAM device. This technique of including an on-chip resistor prevents stored current discharge through the device as the device transitions from a high resistance to a low resistance state. A SPICE simulation is also employed to illustrate the benefit of this approach.