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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

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.

TorKlingberg 6y ago
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.
- geerlingguy 6y ago
  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.
avian 6y ago
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.
swalsh 6y ago
For how long is the equipment for these fabs amortized?
- baybal2 6y ago
  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.
  - VectorLock 6y ago
    Its easy to forget the long tail of smaller ICs these will get use out of for generations.
- monocasa 6y ago
  Not long, around five years after full production.
mlyle 6y ago
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.
- baybal2 6y ago
  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.
  - petra 6y ago
    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.
    - zeckalpha 6y ago
      In the docs they described the naming convention for the processor, which suggests there are more under development
baybal2 6y ago
> how much of the older/larger capacity can be reused? Not only reused, but expanded, and improved over the years. So more than 100% of the original. The biggest surprise of the last few years was the growth in really, really old 200mm fab capacity (late eighties, early nineties tech.)
lizknope 6y ago
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.
- bobsmooth 6y ago
  What happens to the old equipment? Scrap?
  - peterburkimsher 6y ago
    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.
lmilcin 6y ago
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.
- teruakohatu 6y ago
  I think it is safe to say they will come out with a WiFi version. The 40nm will be beneficial then.
  - kelnos 6y ago
    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.
    - lmilcin 6y ago
      I don't understand this fascination with RP2040. You want Rust to work on ARM? There is a huge selection of easy microcontrollers and boards. Large boards, small boards, wifi, ethernet, usb, arduino compatible, anything you want. https://www.st.com/en/ecosystems/stm32-nucleo.html https://www.st.com/en/ecosystems/stm32-nucleo.html 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.
JohnJamesRambo 6y ago
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.

TorKlingberg 6y ago

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.

geerlingguy 6y ago
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.

avian 6y ago

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.

swalsh 6y ago

For how long is the equipment for these fabs amortized?

baybal2 6y ago
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.
- VectorLock 6y ago
  Its easy to forget the long tail of smaller ICs these will get use out of for generations.
monocasa 6y ago
Not long, around five years after full production.

mlyle 6y ago

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.

baybal2 6y ago
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.
- petra 6y ago
  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.
  - zeckalpha 6y ago
    In the docs they described the naming convention for the processor, which suggests there are more under development

baybal2 6y ago

> how much of the older/larger capacity can be reused? Not only reused, but expanded, and improved over the years. So more than 100% of the original. The biggest surprise of the last few years was the growth in really, really old 200mm fab capacity (late eighties, early nineties tech.)

lizknope 6y ago

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.

bobsmooth 6y ago
What happens to the old equipment? Scrap?
- peterburkimsher 6y ago
  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.

lmilcin 6y ago

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.

teruakohatu 6y ago
I think it is safe to say they will come out with a WiFi version. The 40nm will be beneficial then.
- kelnos 6y ago
  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.
  - lmilcin 6y ago
    I don't understand this fascination with RP2040. You want Rust to work on ARM? There is a huge selection of easy microcontrollers and boards. Large boards, small boards, wifi, ethernet, usb, arduino compatible, anything you want. https://www.st.com/en/ecosystems/stm32-nucleo.html https://www.st.com/en/ecosystems/stm32-nucleo.html 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.

JohnJamesRambo 6y ago

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.