# Why It Was Almost Impossible To Make Transistors Less Than 10 nm

Source: https://www.youtube.com/watch?v=MiUHjLxm3V0
Recap page: https://rapidrecap.app/video/MiUHjLxm3V0
Generated: 2025-12-31T16:06:01.219+00:00

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## Quick Overview

The creation of Extreme Ultraviolet (EUV) lithography machines, which enable feature sizes down to 8nm and beyond, was nearly impossible due to fundamental physics challenges, primarily the lack of sufficiently powerful EUV light sources and the inability to create mirrors smooth enough to reflect the necessary short-wavelength light, necessitating the development of complex, multi-layered mirrors (like those using Molybdenum and Silicon) and high-power laser-produced plasma sources (like those achieving 100W power) to continue shrinking transistors as predicted by Moore's Law.

**Key Points:**
- Moore's Law faced a critical challenge around the late 1990s/early 2000s because traditional light sources (like 193nm UV) could no longer print features as small as 90nm, leading to the industry shifting focus to EUV lithography.
- The key technical hurdle for EUV was finding a source powerful enough: early experimental sources produced only about 10W of EUV power, while commercial viability required over 100W (with some aiming for 150W).
- The early X-ray lithography work by Kinoshita and his team (1980s) proved the concept using multilayer mirrors made of Tungsten and Carbon, which reflected around 6% of the light at the required 13.5nm wavelength.
- ASML's high-NA EUV machines overcome the Rayleigh equation limits by using projection optics with numerical apertures (NA) exceeding 1.0 (up to 0.55 for low-NA, later higher) and employing complex mirror systems (like those from Zeiss) to precisely focus the light.
- The EUV light source (Laser Produced Plasma) requires extremely high energy pulses (e.g., 15 mJ) hitting a tin droplet traveling at high speed (50,000 droplets per second) to generate the necessary 13.5nm light, which is then collected by specialized mirrors.
- The extreme precision required for these systems is highlighted by the need for mirror surface roughness less than 0.1 nanometers, far smoother than a playing card, and the environment must be extremely clean (ASML fabs allow only 10 particles/m³ of 0.1-micron particles, compared to 10,000 in operating rooms).
- Despite early skepticism and funding setbacks (like the DOE ending funding for the National EUV Lithography Program in 1996), collaborative efforts, including EUV LLC, led to the development and commercialization of EUV lithography, exemplified by the ASML Twinscan NXE:3300B system.

![Screenshot at 1:01: 400:ASML's EUV machine schematic showing the complex path of the EUV light through the illuminator optics, projection system, and reticle stage.](https://ss.rapidrecap.app/screens/MiUHjLxm3V0/00-01-01.jpg)

**Context:** The video explains the immense scientific and engineering challenges overcome to develop Extreme Ultraviolet (EUV) lithography, the technology required to continue shrinking transistors on computer chips beyond the limits of traditional deep ultraviolet (DUV) lithography, as predicted by Moore's Law. The narrative covers the historical context, starting with early X-ray lithography experiments in the 1980s by Hiroo Kinoshita, the subsequent industry consortium (EUV LLC) formed to pursue EUV, the critical role of ASML in developing the necessary light source and optics, and the extreme precision required at every stage of the process.

## Detailed Analysis

The video explains that the continuation of Moore's Law, which previously saw transistor density double every 18-24 months, stalled around 2005 due to the physical limitations of light sources, specifically the inability of 193nm light to print features smaller than 90nm. The solution became Extreme Ultraviolet (EUV) lithography, using light with a wavelength around 13.5nm. Early X-ray lithography by Hiroo Kinoshita in the 1980s showed promise using multilayer mirrors (Tungsten/Silicon) reflecting about 6% of the light. The central challenge for EUV was creating a source powerful enough; early experimental sources produced only about 10W, while the industry needed over 100W, eventually reaching 11W on an early test stand and eventually aiming for 150W. The successful EUV system relies on complex optics (like those developed by Zeiss) and the ASML EUV source, which vaporizes a tin droplet with a laser pulse to create a plasma emitting 13.5nm light. This light is reflected by multilayer mirrors (like Mo/Si or Mo/Be, the latter offering higher reflectivity but being toxic) and focused onto the wafer. The precision required is staggering: features must be printed with sub-nanometer accuracy, and the cleanroom environment must be 1000 times cleaner than a hospital operating room (ASML requires 10 particles/m³ vs. 10,000 in an OR). Despite early skepticism and industry funding issues (like the US government cutting off funding for the National EUV Lithography Program in 1996), collaboration, including ASML and EUV LLC (formed by Intel, Samsung, TSMC, etc.), led to commercialization, with the first commercial machines shipping around 2012 and producing yields that continued to push Moore's Law forward.

### Historical Context

- Moore's Law faced a slow-down around 2005 as 193nm lithography hit physical limits
- Early X-ray lithography research by Hiroo Kinoshita in 1980s utilized multilayer mirrors (W/Si) reflecting ~6% of 13.5nm light
- US government funding for the National EUV Lithography Program ended in 1996, forcing industry collaboration via EUV LLC.

### EUV Source Technology

- The source uses a laser pulse to vaporize tin droplets (30µm diameter, 50,000 per second) into plasma that emits 13.5nm EUV light
- Early test stands achieved 10W, but commercial viability required over 100W (ultimately reaching 11W, then 100W+ in later tests).

### Optics and Precision

- The High-NA EUV machine uses a complex mirror system (like Zeiss's mirrors) to precisely focus the light
- The numerical aperture (NA) increased from 0.33 to 0.55 and beyond to shrink feature sizes down to 8nm and smaller features.

### The Process

- Light passes through a reticle, is reflected by multiple mirrors (including the collector mirror that must be extremely smooth, <1nm roughness), and projected onto the photoresist-coated wafer.

### Physical Constraints

- The process must maintain extreme cleanliness (ASML cleanrooms have 10 particles/m³ vs. 10,000 in ORs) and manage high-g forces (>20g's) on the reticle stage.

### Industry Adoption

- Despite early skepticism, the industry (Intel, Samsung, TSMC) invested billions ($4.1B from Intel alone in 2012) to fund ASML's development, leading to commercial machines by 2012 and onward.

![Screenshot at 1:01: 400:ASML's EUV machine schematic showing the complex path of the EUV light through the illuminator optics, projection system, and reticle stage.](https://ss.rapidrecap.app/screens/MiUHjLxm3V0/00-01-01.jpg)
![Screenshot at 0:00: A microchip component resting on a fingertip to illustrate the small scale of modern electronics.](https://ss.rapidrecap.app/screens/MiUHjLxm3V0/00-00-00.jpg)
![Screenshot at 0:35: 45:A chart illustrating Moore's Law, showing feature size decreasing as lithography wavelength progresses from 1cm to 23nm.](https://ss.rapidrecap.app/screens/MiUHjLxm3V0/00-00-35.jpg)
![Screenshot at 1:01: 01:ASML's NXE:3300B EUV lithography machine, highlighting its massive size and complexity.](https://ss.rapidrecap.app/screens/MiUHjLxm3V0/00-01-01.jpg)
![Screenshot at 49:56: A comparison of particle counts: ASML cleanrooms \(10 particles/m³\) vs. Operating rooms \(10,000 particles/m³\) for 0.1-micron particles.](https://ss.rapidrecap.app/screens/MiUHjLxm3V0/00-49-56.jpg)