Temperature Impact on Reliability and Manufacturing of Embedded HfOx-Based RRAM: a Novel Pre-coding Method for Bypassing Soldering Reflow

This paper proposes a novel pre-coding method that enables bypassing the soldering reflow issue in resistive memory devices called RRAM. This method is based on the difference between forming and set voltages distributions to discriminate virgin memory cells from those in which data were pre-coded before the soldering step. This procedure enables data recovery through the application of a voltage pulse over the whole memory array. This method, demonstrated on bipolar HfO2-based resistive elements, can be extended to all RRAM devices that exhibit a significant margin between forming and set voltages distributions. Soldering reflow issue & pre-coding technique In few microcontrollers applications (i.e. security smartcard, firmware or subset of OS storage or end-customer code with typical dimension of 0.5 MB), writing a code at wafer level, before packaging and soldering, is mandatory to guarantee data confidentiality. During soldering, non-volatile memory arrays are thermally stressed at about 260°