Silicon has driven the global technology boom for nearly 50 years. Now we have squeezed every drop of its usefulness. The microprocessor manufacturing technology we rely on is reaching serious limits. By 2005, the current methods will no longer be effective. Chip manufacturers have no choice but to find new ways to put more transistors on top of the silicon.
Type Extreme Ultraviolet Lithography (EUVL). This technology is expected to maintain the importance of silicon until the end of this century.
The current industry standard is Deep UV Lithography. It works just like a photo. The light is focused through the lens and a circuit pattern is engraved on the silicon wafer. Manufacturers are concerned that this will not continue. Physics intervenes.
Using extreme ultraviolet (EUV) light to etch transistors changes everything. The resulting microprocessor could be 100 times faster than today’s best chips. Memory recording takes the same leap forward. This article describes the current lithography technology and how EUVL will replace it starting around 2007.
Make chips
To understand the revolution, it is necessary to understand the current situation. Microprocessors or computer chips are made using photolithography. In particular, we can now create chips inside computers using deep UV lithography.
Lithography is basically physical photography. Cameras use light to record images on film. In the manufacture of chips, light is used to transfer images to the substrate. In this case, the substrate is silicon.
The process starts with a mask. Think of it as a template for circuit designs. Light shines through this mask. It then passes through a series of optical lenses. These lenses reduce the image. A small image is projected onto a silicon or semiconductor plate.
The disc is coated with a liquid plastic called photoresist. Sensitive to light. The mask is placed on the disc. When light hits the silicon, it hardens the photoresist in the exposed areas. Unexposed photoresist remains viscous. The chemicals wash away the dirt. All that remains is the cured photoresist and exposed silicon.
The secret of power is the size of the wavelength. The shorter the wavelength, the smaller the property. More transistors can be fed to the wafer. More transistors means faster and more efficient microprocessors.
Let’s compare Intel Pentium 4 and Pentium 3. Pentium 4 contains 42 million transistors. Pentium 3’s capacity is only 28 million. The higher the density, the higher the speed.
Since 2001, deep UV lithography uses a wavelength of 240 nanometers. A nanometer is a billionth of a meter. Current technology will fail as manufacturers move towards 100 nm wavelengths.
Why? Glass lenses absorb shorter wavelengths. Light never reaches the silicon. Circuit pattern is not created. The disk remains empty.
This is where EUVL comes into play. Glass lenses have been replaced with mirrors. Mirrors reflect light without absorbing it. This ensures that the pattern transfers correctly.
The next generation chips are at least five times more efficient than the chips made in 2001. But there is another driving force behind this change.
Moore’s Law
Gordon Moore had a vision. More than 35 years ago, he predicted that the transistor density of a microprocessor would double every 18 months. We call it Moore’s Law. This has been the case for decades. Computers are getting faster and faster. less. Stronger.
But by 2001, the industry was struggling.
Experts believe that deep ultraviolet (DUV) lithography reached its physical limits around 2004-2005. Without new processes, the law will be broken. The narration stops. This industry needs a miracle.
That miracle is EUV lithography.
If deep UV technology fails, chipmakers will move to extreme UV technology. This change is expected to extend Moore’s Law for another 10 years. target? 2007 Introduced 10 GHz microprocessor.
Let’s think about the basic state. In May 2001, Intel’s fastest Pentium 4 processor operated at a frequency of 2.4 GHz. 10 gigahertz is a big leap. It’s not just about speed. It’s about survival in a shrinking world.
“EUV lithography allows us to create chips with feature sizes small enough to support 10 GHz clock speeds. However, that is not always possible.”
– Don Sweeney, EUV Lithography Program Director, Lawrence Livermore National Laboratory
The bottleneck is scale. Deep ultraviolet light can shape circuits up to 100 nanometers in size. It’s the ceiling. EUV can decrease even further.
“We need to make integrated circuits down to 30 nanometers,” Sweeney said. “With EUV lithography, it is clearly possible.”
Less functionality means more transistors per chip. The more transistors, the higher the clock speed. The calculation is easy. Not so in technology.
Battle for EUVL access
Those who control technology control the future.
In April 2001, a consortium called EUV LLC launched the first prototype of a full-scale EUV lithography machine. This is a difficult task.
EUV LLC is more than just a company. This is a league of giants.
- Intel
-AMD - IBM
- Micron
- Infineon
- Motorola
The competitors collaborated with three DOE research facilities. This group is collectively known as the Virtual National Laboratories. This includes:
-Sandia National Laboratories
– Lawrence Livermore National Laboratory
– Lawrence Berkeley National Laboratory
Why cooperate? The costs are prohibitive for individual companies. The stakes are too high. But the reward is there.
The main benefit of joining an alliance is priority. Members have first access to new technology. If you don’t participate, you’re stuck with the old DUV process. Eventually you will fall behind.
The race for 10 GHz processors is on. And it all starts with light.
The core of extreme ultraviolet lithography (EUVL) begins by targeting a xenon gas stream with a laser. The laser heats the gas until it becomes a plasma. The electrons are removed and the plasma emits 13 nm of light. This wavelength is too short for the human eye to detect.
The light enters the condenser. The condenser collects light and directs it to the mask. The mask is not glass. It’s a mirror. Absorbers is applied to certain parts of the mirror to block light. The other mirror reflects it. This creates a pattern on one layer of the computer chip.
Physical principles of miniaturization
The pattern is reflected from 4–6 multilayer mirrors. These mirrors reduce the size of the image and focus it on the silicon wafer. Each mirror bends the light slightly. It works like a camera lens, but with a mirror instead of glass.
Wavelength is everything. The shorter the wavelength, the better the image. Consider taking still photos. Image quality depends on many factors. The first is the wavelength of light. The shorter the better. This is a natural law.
Before EUVL, things were simpler. In 2001, deep UV lithography used 248 nanometers of light. By May 2001, some manufacturers began to switch to 193 nm light. EUVL uses 13 nm of light. The shorter the wavelength, the clearer the pattern on the wafer. The sharper the pattern, the faster the microprocessor.
Vacuum mirror coating
This process takes place in a vacuum. Air absorbs these short wavelengths. There is no room for ambient gas.
The mirror is coated with molybdenum and silicon. This coating reflects almost 70% of 13.4 nm EUV light. The remaining 30% is absorbed. Without this coating, the light would disappear before reaching the wafer.
“When you take a photo of something, the quality of the photo is determined by many factors… and the first factor is the wavelength of light you used to take the photo.” — Sweeney
The mirror should be almost perfect. Small defects in the coating can compromise the optical geometry. Variations in printed circuit patterns. The chip is not working properly.
[Related articles: How semiconductors work, How microprocessors work, CPU quiz, How computers work, How cameras work, How lasers work, How lithography works, Can computer chips be air-conditioned?]
[Other links: EUVL: Imagining the Future, Keeping Moore’s Law “More”, Extreme Ultraviolet (EUV) Lithography, Intel: How Chips Are Made, “Scientific American”: Getting More from Moore’s Law]
