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How to make a CPU – a simple picture-based explanation

blog.robertelder.org

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Re: How to make a CPU – a simple picture-based explanation

#81

Post by nynx »

GhettoComputers wrote: post #78
nynx wrote: post #54

It'd be really awesome if microprocessors, even at a low-end process node like 130 nm, could be made with room-sized machines or smaller. There's a lot of space for companies wanted to manufacture their own MCUs, for instance, without relying on massive supply chains. I think this'll happen at some point, as silicon manufacturing hits final roadblocks and becomes increasingly commoditized, but it'd be nice if it were…

The author misleads you with a point I brought up, it is not possible without globaliziation providing essential raw materials components that have no replacement unless that is your local environment. Spruce Pine has silicon that gives the US microchip supremacy that has dominated for the entire duration of manufacturing. It will never be commoditized that you can take off the shelf raw materials from anywhere local…

I don't think it's inherent that doped silicon will stay the dominant microelectronics substrate and I think it's plausible that people will find new ways to grow it that don't require excellent raw materials.

Re: How to make a CPU – a simple picture-based explanation

#82

Post by robbiep »

GhettoComputers wrote: post #67
kayson wrote: post #24

Circuit designer here - feel free to ask any questions about the manufacturing process, design etc. Having a thorough understanding of the process, I thought this was hilarious. But if you really want to understand the process, it's pretty terrible. It spends 10 steps on making a wafer, and then the bulk of the actual process is condensed to 16.

Can you talk about if the US has microchip supremacy due to raw materials from Spuce Pine's pure silicon, and if there are any sources that are almost as good or being used instead? Is it almost like De Beer's diamond monopoly? Do you use any countries or specific factories that do better refinement or are the raw materials directly shipped to the manufacturing country? What do you make from the wafers usually? Are c…

I’d never heard of Spruce Pine, interesting. I wasn’t able to read the wired article but another article said it wasn’t the silica/silicon that’s the world-beater there though, it’s the quartz for use in crucibles etc?

Also - does the US really have microchip supremacy? The highest tech fabs are non-us (Samsung and TSMC)

Re: How to make a CPU – a simple picture-based explanation

#83

Post by bullen »

kayson wrote: post #24

Circuit designer here - feel free to ask any questions about the manufacturing process, design etc. Having a thorough understanding of the process, I thought this was hilarious. But if you really want to understand the process, it's pretty terrible. It spends 10 steps on making a wafer, and then the bulk of the actual process is condensed to 16.

Have you ever used https://www.fossi-foundation.org?

If I had the skills I would immediately investigate how to couple a RISC-V CPU with some open GPU on that platform!

Re: How to make a CPU – a simple picture-based explanation

#84

Post by gautamcgoel »

kayson wrote: post #24

Circuit designer here - feel free to ask any questions about the manufacturing process, design etc. Having a thorough understanding of the process, I thought this was hilarious. But if you really want to understand the process, it's pretty terrible. It spends 10 steps on making a wafer, and then the bulk of the actual process is condensed to 16.

Suppose I want to make a custom ASIC with 20B transistors. I have a lot of money to spend but no semiconductor experience. How do I go about hiring good chip designers? How much $ should I realistically expect to spend on design, verification, and fabrication, respectively? I've heard $20M is the ballpark for a mask on a leading edge node. What is the marginal cost per CPU?

Re: How to make a CPU – a simple picture-based explanation

#85

Post by shhsshs »

capableweb wrote: post #29

I recall there being a game mentioned somewhere here on HN, where you start with basic logic gates (I think), and you build up a fundamental CPU at the end of the game, using the parts you discovered along the way. Problem is, I don't remember what the game is called, and no amount of searching seems to help me. Anyone know what it was called?

- Turing Complete (2-dimensional circuit building, mission-based): https://store.steampowered.com/app/1444480/Turing_Complete/

- NandGame (2-dimensional circuit building, mission-based): https://nandgame.com/

- Logic World (3-dimensional circuit building, no missions/goals yet): https://store.steampowered.com/app/1054340/Logic_World/

Re: How to make a CPU – a simple picture-based explanation

#86

Post by wrycoder »

GhettoComputers wrote: post #60
wrycoder wrote: post #55

Earlier quoted context omitted.

He’s explaining, as crudely as possible, what’s going on in the semiconductor industry as a whole. Even Shenzen and TSMC are only small parts of it. High purity polysilicon is still produced by zone refining.

Yes it is refined and doped, my point is that he leaves out the sourcing of essential materials that you don't refine but must get that is already pure, it has to be purer than any random silicon its like saying just get any sand that people will assume comes from beaches for construction when its essential that they are not worn or have rounded edges, except this is so specialized that it must come from one mine in…

The BBC article is referring to high purity quartz, not silicon. It is used to make a quartz crucible - a large cup - of that high purity quartz. It’s essential that the crucible not contaminate the polysilicon.

(A note in passing: the semi industry doesn’t use hyperpure silicon. They use a lesser grade and add epitaxial layers.)

The crucible can stand the high temperature of molten silicon. The purified polycrystalline silicon is melted in the crucible. Then a single crystal ‘seed’ is dipped in the molten silicon and slowly withdrawn, while rotating. That’s how you make a high purity single crystal silicon ingot.

Before it’s zone refined, the poly is synthesized by reducing high purity silane gas (SiH4), which was in turn produced from quartz sand.

It would be interesting to know if the industry is still using natural quartz crucibles - the latest wafer size is now 450 mm - nearly 18 inches. Maybe someone else here can comment whether the traditional pulling process will be used at 450 mm.

Re: How to make a CPU – a simple picture-based explanation

#87

Post by kayson »

7373737373 wrote: post #75
kayson wrote: post #24

Circuit designer here - feel free to ask any questions about the manufacturing process, design etc. Having a thorough understanding of the process, I thought this was hilarious. But if you really want to understand the process, it's pretty terrible. It spends 10 steps on making a wafer, and then the bulk of the actual process is condensed to 16.

Do you think chips in the 10k-100k transistor range will some day be able to be produced by hobbyists? Or are the chemicals simply too dangerous and machines too expensive to be affordable at that scale?

No, I don't think so. But it's not because of the chemicals or machines. There's not really any demand for it. Most hobbyist "ICs" are fully digital and can already be realized on an FPGA. For simpler applications, you can probably program a microcontroller to do what you want.

Integrated circuits are appealing to industry because they're integrated - they can be smaller and they reduce cost (long term; still need the upfront investment). These are important things for many products, especially in RF, but they aren't really driving factors for hobbyists.

That being said, people are trying! http://sam.zeloof.xyz/second-ic/

Re: How to make a CPU – a simple picture-based explanation

#89

Post by kayson »

bullen wrote: post #83
kayson wrote: post #24

Circuit designer here - feel free to ask any questions about the manufacturing process, design etc. Having a thorough understanding of the process, I thought this was hilarious. But if you really want to understand the process, it's pretty terrible. It spends 10 steps on making a wafer, and then the bulk of the actual process is condensed to 16.

Have you ever used https://www.fossi-foundation.org ? If I had the skills I would immediately investigate how to couple a RISC-V CPU with some open GPU on that platform!

With most open source hardware efforts, like this, it's not really so much circuit design as it is just code. All of the open source efforts I've seen revolve around digital circuits, which are written in some kind of RTL and turned into an actual circuit by completely automatic processes. It's still great, and I fully support them, but there's a massive amount of non-digital that's crucial to getting these systems up and running. Not to mention that even if you have an open source CPU RTL, for example, you'll need access to a closed-source and often NDA-blocked PDK (process development kit), fabrication company, etc. I remember seeing some efforts at open sourcing the PDK part as well, but remember being unimpressed.

Re: How to make a CPU – a simple picture-based explanation

#90

Post by 7373737373 »

kayson wrote: post #87
7373737373 wrote: post #75

Earlier quoted context omitted.

Do you think chips in the 10k-100k transistor range will some day be able to be produced by hobbyists? Or are the chemicals simply too dangerous and machines too expensive to be affordable at that scale?

No, I don't think so. But it's not because of the chemicals or machines. There's not really any demand for it. Most hobbyist "ICs" are fully digital and can already be realized on an FPGA. For simpler applications, you can probably program a microcontroller to do what you want. Integrated circuits are appealing to industry because they're integrated - they can be smaller and they reduce cost (long term; still need th…

Yeah, I saw and am amazed by his work, which made me wonder whether chip manufacturing could get as streamlined, compact and mainstream as 3d printing is today!
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