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by aidenn0 3980 days ago
I'd like to see a source for the "similar density to DRAM" my understanding is that it's an 8F2 footprint, and scaling it down to small process nodes is still problematic, even with spin-torque transfer.

All that being said, there are people who make the exact same claims about RRAM as you quote for MRAM, which 3d-xpoint appears to be.

Also note that you can buy MRAM parts right now, which are replacements for battery-backed SRAM, and are more radiation resistant than SRAM. Densities are fairly low though.

2 comments

> my understanding is that it's an 8F2 footprint

Where does that come from? From everything I've read is that its structure is fairly analogous to DRAM, "simply" replacing the capacitor with the magnetic tunnel junction, which has its component layers stacked vertically, thus not really taking up any extra space.

> scaling it down to small process nodes is still problematic, even with spin-torque transfer.

yeah, that's the main gist I'm getting too from following the news.

> people who make the exact same claims about RRAM as you quote for MRAM, which 3d-xpoint appears to be.

At least the xpoint incarnation still seems to be slower than DRAM according to that article, while MRAM is being offered as SRAM/battery-backed DRAM drop-in replacement.

>> my understanding is that it's an 8F2 footprint

> Where does that come from? From everything I've read is that its structure is fairly analogous to DRAM, "simply" replacing the capacitor with the magnetic tunnel junction, which has its component layers stacked vertically, thus not really taking up any extra space.

I did some searching; older references show an 8-12F2 size, for e.g. the Everspin parts. Grandis claims a 6F2 size which is indeed comparable to DRAM.

>> people who make the exact same claims about RRAM as you quote for MRAM, which 3d-xpoint appears to be.

> At least the xpoint incarnation still seems to be slower than DRAM according to that article, while MRAM is being offered as SRAM/battery-backed DRAM drop-in replacement.

Right, the product they are claiming they will manufacture next year is slower than DRAM and less dense than flash. (Frustratingly I couldn't find a reference for if they are talking about latency or throughput when they say "slower"; it makes a big difference for which applications will be hurt by the performance mismatch).

However, there doesn't appear (yet) to be a fundamental reason why resistive ram must always be slower than DRAM, nor a fundamental reason why they couldn't do MLC tricks with it, so you can't say all RRAM will be slower than DRAM and less dense than NAND.

Fair point, perhaps I should have phrased it more as a technology with similar applications. I find it interesting that there are parts available now, albeit made on a 180nm process apparently.