As embedded flash hits a physical and economic scaling wall below 22nm, a new on-chip memory is needed. Ilan Sever of WeeBit Nano joins to explain how Resistive RAM (ReRAM) is positioned to become the new standard by offering a low-cost, high-endurance alternative. Ilan details how ReRAM's simple back-end-of-line integration, automotive qualification, and future applications in AI in-memory compute create a compelling replacement for the incumbent technology.
"In geometries below 28 or 22 nanometer, flash reached its physical limit, actually. So physically you cannot implement embedded flash anymore and the industry had been looking for alternative technologies for a few decades now."
— Ilan Sever, WeeBit Nano
Key Takeaways:
- The inflection point for on-chip memory is physical. Embedded flash cannot scale below the 28/22nm node because its floating gate becomes too small to reliably hold charge.
- The economic problem with eFlash is its 25-30% cost increase, a result of adding 8-10 extra masks to a standard CMOS process—a non-starter for cost-sensitive MCUs.
- ReRAM's manufacturing advantage is its simplicity. It's built in the back-end-of-line (BEOL) metal layers, adding only two masks and not interfering with the sensitive transistors below.
- The physics are different: ReRAM isn't storing charge, it's changing resistance by using voltage to form or dissolve a conductive filament of oxygen vacancies in a dielectric.
- Automotive qualification is the key market validation. WeeBit's ReRAM is qualified for the AEC-Q100 standard and demonstrates 100,000 write cycles—10x that of typical eFlash.
- The business model isn't just a recipe; it's a full IP module with the bit cell, analog circuits, digital logic, and programming algorithms, which is what SoC designers actually need.
- Beyond replacing flash, ReRAM (as a memristor) is a foundational technology for future in-memory compute (IMC) AI accelerators that perform calculations inside the memory to save power.
Chapters:
0:00 The Overlooked Memory
4:15 The eFlash Scaling Wall
6:03 Four Uses of NVM
23:19 The Cost of eFlash
27:29 Introducing ReRAM
32:25 How ReRAM Works
37:12 Fab-Friendly Materials
42:14 Automotive Qualification
44:30 The Vertically Integrated IP Model
51:13 Future: In-Memory Compute
54:19 Innovation Story: Self-Trimming
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