Why are lithography machines used to manufacture chips so expensive?

From Quartz to Wafer: Preparing the Raw Materials

First, quartz is crushed, ground, and heated to form a 200 kg monocrystalline silicon ingot. This ingot is sliced into wafers less than 1mm thick and then polished until their surface smoothness reaches 0.1 nanometers. These become the wafers—the base material for chips. A pack of 25 wafers is sent into the fab. Each wafer can produce about 230 chips, each the size of a fingernail, and goes through thousands of steps, the most important of which happen inside the lithography machine. The lithography machine is as large as two buses stacked on top of each other and is packed with precision instruments.

The Precision of Lithography Machines

Engineers begin by printing each layer’s intricate transistor layout onto a photomask. These circuit lines are thinner than one ten-thousandth of a human hair. The finer the lines, the smaller the transistors and the more that can fit on a single chip—boosting its performance. Laser etching was once used but fell short in precision. Now, Extreme Ultraviolet (EUV) light is used. Since EUV light doesn’t exist in nature, it must be created artificially.

Generation and Use of EUV Light

Inside a vacuum chamber, an intense laser beam—15 times more powerful than metal-cutting lasers—is fired at molten tin droplets. The droplets vaporize into plasma, emitting EUV light. This light is then collected and reflected onto the wafer to etch circuits. The precision is akin to an astronaut on the moon hitting someone’s fingertip on Earth with a laser beam. Additionally, EUV light is easily absorbed, so it cannot be directed with glass lenses and instead requires specially coated mirrors. A vacuum is also necessary because air itself would absorb the light.

Precision Control and Mirror Systems in Lithography

To accurately direct EUV light onto wafers, lithography machines use an extremely complex mirror system. Because EUV light cannot pass through air or glass, traditional lenses are useless. Instead, multi-layered mirrors with atomic-level smoothness—tolerances of just a few angstroms—are used. Alignment precision? Imagine hitting a coin on the moon from Earth with a laser—that’s the level of accuracy required.

After exposure, wafers undergo etching, ion implantation, film deposition, and chemical mechanical polishing. These must occur in ultra-clean rooms—tens of thousands of times cleaner than an operating room. A single dust particle larger than 0.1 microns could ruin an entire chip.

Image Source: ASML Official Website

The Multi-layered Structure of Chips

Each chip contains hundreds of circuit layers. Every layer must align perfectly with the one below it—with an alignment error margin of only a few nanometers. Imagine stacking hundreds of patterns precisely within the width of a single human hair. Each one must be perfectly in place.

Purity Inspection

Materials used in manufacturing must be of exceptional purity. Photoresist, etching fluids, dopant gases, and others require “8-nines” purity—99.999999%. Even the slightest impurity could ruin an entire batch. To detect such defects, fabs are equipped with sophisticated tools capable of identifying flaws smaller than viruses. Each wafer undergoes over a thousand steps across two to three months, and even one mistake could waste all that effort. That’s why IC packaging and testing is the final, crucial process before delivering finished chips.

Conclusion

Chipmaking is not about crafting a small object—it’s a grand integration of physics, chemistry, materials science, optics, mechanics, software, and thermodynamics. This is why lithography machines are so expensive, and why chips aren’t costly because of their size—but because of the challenge.

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