Name: ムーアの法則を次のレベルに押し上げる極限物理学 (The Extreme Physics Pushing Moore’s Law to the Next Level)
Uploaded: 2021-01-14T10:20:37.000Z
Duration: 11 min 52 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

We’re suiting up to take you inside a clean room that’s building an engineering marvel

that’ll push the entire electronics industry to the next frontier. They're both amazing

machines and scary machines. There's an enormous amount of complexity with them. There's an

enormous number of things that can potentially go wrong. It's something that you don't necessarily

sleep well at night, just having the machine on your floor. It’s about the size of a

school bus, weighing over 180,000 kilograms, with over 100,000 parts, and 3,000 interlocking

cables. Pop the hood and you’ll see lasers shooting tiny droplets of tin, generating

plasma that’ll get collected and reflected by a series of mirrors, to then etch nanoscale

patterns onto chips that’ll eventually go into your next cell phone. And after 30 years

of innovations in physics, chemistry, and material science, it’s about ready for its debut.

An integrated circuit, or chip, is one of the biggest innovations of the 20th

century. It launched a technological revolution, created Silicon Valley, and everyone’s got

one in their pocket. But if you zoomed in on one of those chips, I mean, really zoomed

in, you’d find a highly complex, nanoscale sized city that’s expertly designed to send

information back and forth. Semiconductor lithography is the ultimate alchemy, turning

sand into gold. You start with the silicon wafer. You add insulators, add something called

a gate which you apply a voltage to it, and it turns on or off the flow of electrons.

That's the little switch that's sort of does the zero to one's that you always hear about

You build up a sequence of layers. The network, the streets and buildings

that you need in order to make these transistors and interconnect those transistors.

At the end you can turn that into something that has substantially more value than a bucket

of sand. At big tech conferences, chip manufacturers will announce they’ve hit impossibly small

new milestones, like 22nm then 14nm and 10nm designs. That means they’ve found a way

to shrink the size and increase the number of features on a chip, which ultimately improves

the overall processing power. This is what’s been driving the semiconductor industry - a

drumbeat called Moore’s Law. Moore's Law is an expectation. It's not a natural law. It's

an expectation that we innovate at a pace of roughly doubling the density every two

years. All of those things allow us to offer better products, allow us to offer cheaper

products with the same capability and that in turn drives the demand for the overall

industry. That means that we've got to be able to cram in, more and more functionality

per square millimeter on a chip. All the designs and  streets and everything have to be smaller

and smaller in dimensions. Moore's Law has been predicted to be dying for a long time

and yet it never is. Because each generation of engineers knows it's their expectation

to keep working on it, to keep going at a certain pace. The core technique at the heart

of this expectation is called photolithography. It’s a chip manufacturing process that’s similar

to darkroom photography, but instead of a negative for a picture, they’re using something called

a mask or reticle to expose a geometric print. It's basically a projection system where we have

a light source, a mask or reticle, which is the blueprint, then the wafer. And we have

to manage the light on the way through to get a perfect reproduction of that pattern

on a silicon wafer. That enables you to build all of the billions of transistors that you

need in order to make a functional chip. The light sources are lasers, created from a mixture

of gases, like carbon dioxide or argon fluoride. When excited by an electric current, the gas

molecules will emit laser radiation that are then tuned to a specific wavelength that imprints

the chip design. There’s a drive to get the light source to shorter and shorter wavelengths,

because the shorter it gets, the more transistors you can cram onto a chip. In terms of the

electromagnetic spectrum, what we can see visibly is about 400 and 650 nanometers. The

chip industry’s gone from 365 nm wavelengths to 248 nanometers to something called argon

fluoride immersion. So argon fluoride refers to a wavelength, 193 nanometers.

ultraviolet laser light source. The industry tried to go to 157 nanometer light, and that

failed after companies had invested hundreds of millions of dollars in it. The field then had

to invent new technical tricks for the systems in use today. They actually put water

in between the bottom lens element and the wafer, because the wavelength of light in

water is quite a bit shorter. When I first heard about it, I thought it was just crazy.

You're going to get water all over the stages, and the electronics inside the tool. There

was some very clever engineering that allowed them to contain that water in a little puddle

as the wafer is going back and forth at about 700 millimeters a second.

But that turns out to be coming near the end of

its ability to produce even finer and finer features. So to keep Moore’s Law on track

without breaking the laws of physics, chip manufacturers have been racing to bring this

technology online: Extreme Ultraviolet Lithography. It takes the wavelength of light

from 193 nanometers down to 13.5. The jump is much larger than what we would normally

do. And that's partly because it's more of a disruptive technology. The first academic

work on EUV was done in 1986, when I was still an undergraduate in college. Through my whole

career, we've been hearing that EUV was coming. There was so many fundamental problems with

using these soft x-ray wave lengths for a lithography tool. We're down to the point

where the amount of variation can be measured in atoms. And so you have to work very hard

to have a control of those dimensions. And that is where ASML comes in. ASML is the

most important tech company you've never heard of. We build the big machines that make small

chips. EUV was a massive step for us to undertake. Not only did we need to have an entirely new

scanner because we had to work in a vacuum and at wavelengths where you need to have

only reflective optics which required a huge amount of innovation. But we also needed

a new light source as well. In fact, it's the first time ever, that we've needed to

change the light source and huge elements of the scanner design at the same time. But

for this story, we’re just going to focus on the lasers. Here’s how they work in

the machine. The source of the light is a tiny little droplet of tin. They're smaller

than the diameter of a human hair in which we fire across the vessel and then we intercept

those with a pulsed laser beam of very high power. And I have to hit it with an accuracy

of just a few microns even though it's traveling at, let me say at the speed in excess of the speed limit.

It forms a plasma that emits EUV light. There's a collector mirror that collects that light

and sends it into the scanner. Then there are four mirrors that essentially shape that

light into a slit that bounces off the reticle. You will see a reticle stage doing this, and a

wafer stage doing this. And what is happening is step and scan. Which basically means we

continue to reproduce that particular pattern over and over again. Just to give you a sense

of the mechanical complexity even, the wafer stage itself is something like 200 kilograms

in weight and yet it's able to accelerate faster than a fighter jet.

The thing that probably had people the most skeptical was, getting the power on the source up. When we

started out we didn't generate the power that we wanted and we struggled at the beginning

to understand why. Every year it was slipping out, and the actual power we were getting

was stuck around very low levels, impractical levels. We continued to dive into looking

more fundamentally at the basic plasma physics. What were we missing? It was around about

2015 where we finally unlocked the secret. It's all about exactly controlling how you

deliver that energy to the droplet and then how you would deliver it to the tin afterwards.

It becomes very critical in pushing that conversion efficiency up. You don't just need to hit

the tin droplet with one laser pulse but, in fact, two. The first of those pulses, shapes

the target in a way that enables us to get this high conversion efficiency and then the

second pulse of course, generates that very hot plasma that we need for generating 13.5

nanometers at high power. Once we crested that, it became, I wouldn't say easy, but

at least we saw the path and we were able to make changes to the system and we could

see the immediate benefit. We actually still do