Thermal Budget Reduction for Back-end Compatibility and Control of Resistance Switching Mechanism (Unipolar to Bipolar) in Pr_1-xCa_xMnO₃ (PCMO) RRAM

Abstract

A low thermal budget process for back-end compatible PCMO based RRAM cell is essential for 3D stacked memory. In this paper, we investigate two strategies to engineer low thermal budget processing for bipolar switching - (i) deposition engineering i.e. based on deposition temperature and oxygen partial pressure, (ii) post deposition anneal i.e. based on inert anneal of room temperature deposited PCMO film.. We demonstrate that both deposition and anneal shows a transition temperature above which bipolar switching is realized. Oxygen partial pressure is a key deposition process parameter. As oxygen partial pressure is reduced memory window increases, however beyond an optimal O2 partial pressure, unipolar switching is observed. Inert anneal is more effective in thermal budget reduction as N2/550°C/2min anneal has same memory performance as 650°C/2hour deposition process.

Effect of Morphological Change on Unipolar and Bipolar Switching Characteristics in Pr0.7Ca0.3MnO3 Based RRAM

“…BRS has been explored extensively in PCMO with reactive top electrode [4][5][6][7]. Unipolar PCMO RRAM has been demonstrated recently [8][9][10]. We have recently reported control of URS vs. BRS in PCMO, based on the PLD process conditions i.e.…”

“…p O2 and T, based on DC sweep. Low thermal budget based BRS was also demonstrated by RTA (Rapid Thermal Anneal) of room temperature deposited samples [8]. However, materials origin of URS vs. BRS needs to be investigated.…”