From the twitter thread, someone said it was fabbed by TSMC at 40nm.
I wonder, with the cutting edge moving to smaller and smaller processes (5nm, etc)... how much of the older/larger capacity can be reused? Meaning, are we about to see a ton of cheaper chips like this RP2040 that are using older/slower/obsolete fab capacity? Or is the same equipment able to be used across a family of process sizes?
In other words, once TSMC has X amount of capacity on 40nm, is that capacity always around and fixed to 40nm? If so, I imagine that creating new chips that don't need to be super fast will just become super cheap.
Microcontrollers being on larger processes like this is nothing new. As you mention, it's a way to keep using older fabs, but that's not the only reason.
40nm offers tons of performance for microcontrollers and the die area can still be reasonably small. You tend to want to have lots of variants of microcontrollers for different applications, so mask costs matter. And you tend not to want exotic, very low core voltages and do want high voltage tolerances and strong drivers on the IOs, which mean relatively big geometry-- no matter what your minimum feature size is.
Also, sleep power consumption is important, so low leakage is nice, which is easier to get on large geometry.
40nm is a quite recent move for MCUs, and the mainstream majority can still be anywhere in between 90nm, and 180nm.
Only very few, top of the line MCUs ventured to 40nm, like ESP32 which had no other option because of WiFi eating gates, or ST's MCUs with 3D accelerator on board.
Problem for MCUs is that MCU specific features start to cost too much more in IP, design time, yields, and fab service cost below 90nm. Things like embedded flash, per-model mask memory, SRAM, non-CMOS cells, RF, and other analogue circuitry.
Below 28nm conventional eFlash, and many other things stop scaling, and only proprietary solutions are on the table at the moment.
BayBal, since you're an expert in Semi, I wonder if you can fill in the blanks?
EbenUpton(Raspberry Pi's CEO) , on Twitter:"We get ~20k die per wafer""
A Tsmc 40nm wafer costs about $2300.
How much do you estimate the full chip manufacturing cost for this would be ?
I wonder, because Eben Upton talked about "business model hacking" in regards to this chip, so they may want to do some interesting stuff in the mcu market.
> BayBal, since you're an expert in Semi, I wonder if you can fill in the blanks?
An expert? Ahahh, I never even had formal education in the field, just been trying to enter it, and start studies in it for a few years.
My only real experience with ICs was with a company developing a fancy synchronous rectifier chip what was capable of doing few more tricks with the output waveform besides rectification, and that was mostly just hanging around, and doing complete trivialities like routing, or minimal layout wiggling. I was more useful there as a coffee porter.
> How much do you estimate the full chip manufacturing cost for this would be ?
I don't know how many wafers they buy. I don't know whether they ordered masks from TSMC, or somebody else. I don't know how short they want lead times to be. I don't know if they want to have any device inspection provided. I don't know if they have any agreements on repeated runs, or a flexible capacity purchase. I don't know if they order test, and packaging from TSMC.
From a man who was on Allwinner's original A10 chip team, I heard that the most bare bones 65nm run without mask cost, inspection, or packaging was possible at 1k wafers at $2400-$2500 in 2013-2014 by paying cash 1y in advance.
Today, I'm not even sure if clients are even allowed to, or can order masks on the side these days for latest processes.
The universal advice I heard is that you don't get into 300mm game without at least $10m, or better $20m if you have a brand new, untested design.
The manufacturing cost is tiny. It's .2cm squared, so at 0.05 defects per cm^2, you expect to lose about 0.2% to defects. So-- die manufacturing costs are 2300/(20000*.996) == around 11 cents.
Small run packaging, along with distribution costs, etc, will dominate.
The real cost is amortization of R&D and mask costs.
Don't forget software costs. Raspberry Pi foundation is known for excellent software and Pico seems to be intended that way too.
And that's money well spent, I think. If I'm a hobbyist and am planning on using a grand total of three microcontroller boards, than paying $2 x 3 for "blue pill boards", and then spending hours and hours debugging some obscure problem... that doesn't look like all that great of a deal, compared to paying $5 x 3 and making some use of polished examples and a nice build system:
The fab will eventually be upgraded. I design semiconductors and I have worked at two companies that had their own fabs (I didn't work in the fab)
Back in 1997 the new technology was 0.25 micron (250nm) but we still operated fabs at 0.35, 0.6, 0.8, and 1 micron. I believe these 4 lines operated at 6 different factories.
The next year we shut down the 1 micron fab. The building itself still had all the air filtering and cleanroom facilities. The old equipment (steppers, testers) was removed and new equipment for 0.18 micron was installed. I think this took about a year. At the end we still had 6 factories but the building that used to have all the old stuff was now the cutting edge fab.
Usually the equipment is rented, and returned to the owners.
I spent 4 years in Taiwan working for OSE, a semiconductor packaging company (cutting up silicon wafers, bonding wires onto them, and putting them into little plastic SD cards or RAM chips labelled "Made in Taiwan").
The pick & place machines and ovens weren't owned by OSE - they were on a 30-year lease from other companies in Japan, Germany, etc.
Software updates would void the warranty/lease conditions. One of my tasks was to write a program to measure yields for factory monitoring. This meant figuring out how to use SQL on Windows 2000, with no .NET framework or additional libraries.
My guess is that when the equipment is too old, the original owners either take them back for salvaging, or sell off the pieces as scrap. I went to many scrapyards in Kaohsiung though, and found many treasures like $10 bicycles or old consumer gadgets, but no factory-level machines.
Older processes available for cheap are not a new thing. They do indeed stay around until TSMC decide they're no longer worth running. It's not always cheaper as a larger process wastes more wafer.
I believe Eben Upton mentioned in a Twitter thread somewhere that they were getting thousands of chips off each wafer at the current node size? Only had to order like 20 or 40 wafers for the first production run, something like that.
Microelectronics cutting edge has been moving to smaller processes for the past 70 years. This is nothing new. If anything, the progress has slowed down.
Some fabs get closed down/rebuilt for a different process, some stay and produce parts that don't benefit from higher densities. Last I checked some ICs still get produced in 0.35 um processes. You don't need billions of transistors for an opamp.
I’d just like a documentary about fabs. It seems like an insane secret world of some of the most expensive places on earth. I’d love to know what they do with old ones etc.
This chip is very small and it does not benefit in any possible way from more advanced technological process. And using more advanced process means additional drawbacks and cost increases.
I really hope they do. I just bought a little ESP32 board, and while I'm having fun with it, it's a bummer that it's using an oddball ISA (xtensa). I really want to build for it in rust, but the xtensa llvm and rust forks are beta-ish quality, and there's no working wifi driver yet.
With the RP2040 based on ARM, rust should work on it after someone works up a peripheral support crate, which shouldn't be too hard if the RPi Foundation releases SVD files.
I have a bunch of these. I use them for prototyping before I put together a PCB design but they are fully functional if you want to build a product on them.
All eternity really. Even eighties era equipment is still being bought, and resold. Quite a number of early nineties fabs still work producing pretty much same things for 30 years straight.
I wonder, with the cutting edge moving to smaller and smaller processes (5nm, etc)... how much of the older/larger capacity can be reused? Meaning, are we about to see a ton of cheaper chips like this RP2040 that are using older/slower/obsolete fab capacity? Or is the same equipment able to be used across a family of process sizes?
In other words, once TSMC has X amount of capacity on 40nm, is that capacity always around and fixed to 40nm? If so, I imagine that creating new chips that don't need to be super fast will just become super cheap.