New Transistor Structures At 3nm/2nm • Hacker News Board

Re: New Transistor Structures At 3nm/2nm

#51

Post by marcosdumay » Mon, Jan 25, 2021, 8:14 PM UTC

algorithm314 wrote: post #24

tryptophan wrote: post #11

Earlier quoted context omitted.

Smaller distance -> lower resistance -> less heat -> higher clocks/more stuff per clock allowed with same amount of heat produced -> higher performance.

No smaller dimensions -> thinner wires -> higher resistance per length.

A chip is not composed of cylindrical wires.

Smaller dimensions means you can set a smaller length for the wire.

As you can see on the diagram on this article, there is a large push into increasing the height of the transistors. That has being going on for more than a decade.

About the width, a finer process means you can keep the width of the most critical transistors the same, but can also trade it off into less width (and performance) where it is less important.

So, overall, smaller dimensions leads to lower resistances. You can trade some of the gain for density, but you'll always get some lower resistance.

Re: New Transistor Structures At 3nm/2nm

#52

Post by ben_w » Mon, Jan 25, 2021, 8:19 PM UTC

adwn wrote: post #48

SpaceRaccoon wrote: post #40

Earlier quoted context omitted.

And the "electric signal" is an electromagnetic wave- also known as light. Nowhere did they imply the speed of light in a vacuum, the speed of light in copper is an equally valid interpretation.

> And the "electric signal" is an electromagnetic wave- also known as light. No, it's not. If it were, you'd have photons moving through your copper wire, which would be quite the sensation! A moving electron does create a change in the electromagnetic field, however, so maybe that's where your confusion stems from?

More charitably, charge carriers do move much more slowly than the electric field they transmit[0], and while you’re correct that the time-varying electric field in a processor is not light (nor even a radio wave), if the chips were much larger or much higher frequency the chips and buses would risk becoming antennas and having all the problems that would bring — 5 Ghz ~= 6cm wavelength [1] ~= 3cm half-wave dipole.

[0] https://en.m.wikipedia.org/wiki/Speed_of_electricity

[1] http://www.wolframalpha.com/input/?i=c%2F5ghz

Edit: if the chips were much larger. Smaller chips can go faster without becoming antennae.

Re: New Transistor Structures At 3nm/2nm

#53

Post by mlindner » Mon, Jan 25, 2021, 8:20 PM UTC

Hacker news comment sections on articles about semiconductors always seems to be full of people talking authoritatively about things they clearly don't understand. And this is all visible to someone who only majored in computer engineering and got basic training in transistors and logic design who's day job is now in software. I can only imagine the people who actually know transistors cringing in here (and thus avoid commenting).

Re: New Transistor Structures At 3nm/2nm

#54

Post by deeeeplearning » Mon, Jan 25, 2021, 8:31 PM UTC

mlindner wrote: post #53

Hacker news comment sections on articles about semiconductors always seems to be full of people talking authoritatively about things they clearly don't understand. And this is all visible to someone who only majored in computer engineering and got basic training in transistors and logic design who's day job is now in software. I can only imagine the people who actually know transistors cringing in here (and thus avoi…

Gell-Man Amnesia might interest you.

"Briefly stated, the Gell-Mann Amnesia effect is as follows. You open the newspaper to an article on some subject you know well. In Murray’s case, physics. In mine, show business. You read the article and see the journalist has absolutely no understanding of either the facts or the issues. Often, the article is so wrong it actually presents the story backward—reversing cause and effect. I call these the “wet streets cause rain” stories. Paper’s full of them.

In any case, you read with exasperation or amusement the multiple errors in a story, and then turn the page to national or international affairs, and read as if the rest of the newspaper was somehow more accurate about Palestine than the baloney you just read. You turn the page, and forget what you know.”

Re: New Transistor Structures At 3nm/2nm

#55

Post by Gravityloss » Mon, Jan 25, 2021, 8:48 PM UTC

adwn wrote: post #26

t-writescode wrote: post #22

Earlier quoted context omitted.

It's crazy to think about if you've never thought about this, but the speed of light is a bottleneck for processors. When we get smaller devices, there's literally less distance that needs to be traversed, so more can be done!

> the speed of light is a bottleneck for processors It's not the speed of light [in a vacuum], but electric signal propagation speed in copper.

An electric signal in a wire can't travel faster than the speed of light.

Re: New Transistor Structures At 3nm/2nm

#56

Post by systemvoltage » Mon, Jan 25, 2021, 8:55 PM UTC

tryptophan wrote: post #11

everdrive wrote: post #10

What is the benefit of smaller transistors? Serious question. Why does it matter if I have 7nm vs. 5nm vs. anything else?

Smaller distance -> lower resistance -> less heat -> higher clocks/more stuff per clock allowed with same amount of heat produced -> higher performance.

None of these reasons are as important as transistor count / mm^2. If you can shrink die size in half, you can effectively reduce its cost by half as well. Processing wafers through 400 steps in the fab and its capacity is limited by how many useful chips you can build on a given 300mm wafer.

Re: New Transistor Structures At 3nm/2nm

#57

Post by baybal2 » Mon, Jan 25, 2021, 9:12 PM UTC

tryptophan wrote: post #11

everdrive wrote: post #10

What is the benefit of smaller transistors? Serious question. Why does it matter if I have 7nm vs. 5nm vs. anything else?

Smaller distance -> lower resistance -> less heat -> higher clocks/more stuff per clock allowed with same amount of heat produced -> higher performance.

> Smaller distance -> lower resistance -> less heat -> higher clocks

Smaller distance -> lower capacitance -> higher clocks

Re: New Transistor Structures At 3nm/2nm

#58

Post by mrRandomGuy » Mon, Jan 25, 2021, 9:13 PM UTC

mlindner wrote: post #53

Hacker news comment sections on articles about semiconductors always seems to be full of people talking authoritatively about things they clearly don't understand. And this is all visible to someone who only majored in computer engineering and got basic training in transistors and logic design who's day job is now in software. I can only imagine the people who actually know transistors cringing in here (and thus avoi…

You can expand this astute observation to _many_ things other than semiconductors around these parts

Re: New Transistor Structures At 3nm/2nm

#59

Post by MayeulC » Mon, Jan 25, 2021, 9:19 PM UTC

mlindner wrote: post #53

Hacker news comment sections on articles about semiconductors always seems to be full of people talking authoritatively about things they clearly don't understand. And this is all visible to someone who only majored in computer engineering and got basic training in transistors and logic design who's day job is now in software. I can only imagine the people who actually know transistors cringing in here (and thus avoi…

I tend to disagree; while some comments seem to be clearly wrong, mistakes tend to be pointed out by other commenters, and you can always check bios. It's a bit riskier on stories that don't stay on the front page, I'll grant you that.

And there can be a bit of Dunning-Kruger if you work in a related field too.

Re: New Transistor Structures At 3nm/2nm

#60

Post by mrfusion » Mon, Jan 25, 2021, 9:21 PM UTC

mlindner wrote: post #53

Hacker news comment sections on articles about semiconductors always seems to be full of people talking authoritatively about things they clearly don't understand. And this is all visible to someone who only majored in computer engineering and got basic training in transistors and logic design who's day job is now in software. I can only imagine the people who actually know transistors cringing in here (and thus avoi…

It’s not just articles about semi conductors ... you just happen to have some knowledge in that area so you notice it.

You’ve just discovered another instance of the gellman amnesia effect.