Physics / mechanism
Memristors are two-terminal passive devices whose resistance depends on the history of current or voltage applied — resistance is non-volatile state. The dominant physical mechanisms are filamentary conductive-bridge RAM (CBRAM, ionic metal migration) and valence-change memory (VCM, oxygen vacancy filament modulation), plus phase-change and ferroelectric variants. Key parameters: switching speed (sub-10 ns demonstrated), endurance (10⁶–10⁸ cycles for HfOₓ VCM), retention (>10 years at 85 °C), on/off ratio (10²–10⁴), and multi-level cell (MLC) programmability (3–4 bits/cell demonstrated in research). State of the art: TSMC and GlobalFoundries both offer embedded RRAM (1T1R) in 22–28 nm nodes for MCU/IoT NVM; crossbar arrays at 4 F² density are production-feasible. The fundamental appeal is CMOS back-end integration — no new fab infrastructure required beyond dielectric stack tuning.
Competitive landscape
The primary NVM competitors are embedded Flash (eFlash) and embedded MRAM (STT-MRAM). eFlash is mature but hits a wall below 28 nm due to tunnel oxide scaling. STT-MRAM offers faster write and better endurance but higher write current density and process complexity. PCM (phase-change) competes for storage-class memory at higher density. Neuromorphic-specific competition comes from SRAM-based analog compute-in-memory and ferroelectric FETs (FeFETs). CBRAM trails VCM on endurance; VCM trails PCM on MLC precision.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.