In the world of semiconductor production, things get smaller all the time. The industry's most famous precept is Gordon Moore's 1975 prediction that the number of transistors squeezed onto a single integrated circuit would continue to double every two years.

It may have been a self-fulfilling prophecy, but Moore's law has proved a surprisingly reliable measure of the industry's evolution. That evolution has led to the development of mind-bogglingly complex devices. The main processor for Microsoft's latest Xbox One X games console, for example, incorporates seven billion transistors on a 359-square-milimeter silicon die. That's 19.5 million transistors per square millimeter. Chip manufacturer Intel has developed chips that it says have 100 million transistors per square millimeter.

Building such intricate devices requires mastery of a host of highly sophisticated techniques and technologies, from materials science to statistical process control. But all modern semiconductor manufacturing processes rely on one major process to create precise features at microscopic scale: photolithography.

Photolithography is simple in principle. A silicon wafer is cleaned, treated and coated with a material know as photoresist. Ultraviolet light is then projected via a mask to create a precise pattern of features on the surface of the photoresist. That light causes a chemical change that allows some parts of the photoresist to be dissolved away with a special developer solution. The surface of the wafer is then etched with liquid or plasma to create the desired features.

The practice, of course, is far more complicated. The manufacture of a complete integrated circuit requires multiple photolithographic steps. The patterns etched onto the wafers must be precisely aligned and perfectly formed. And as the features required on modern chips are just a handful of atoms across, the technology necessary to achieve the required accuracy at production volumes is extraordinarily sophisticated.

The majority of the world's semiconductor makers go to one place for photolithography equipment: Netherlands-based ASML. The 35-year-old firm has an estimated 80 percent market share in the segment. "Our machines drive the shrink of feature sizes that enables the growth of the industry," says Yolanda van Norden, Senior Director of Supply Chain Management Logistic Service Operations at the company.

ASML's day-to-day work involves cutting-edge science and engineering research. Some 85 percent of the company's 16,500 employees are graduates and more than half of them are qualified to master's degree level or higher. The company spends EUR1.1 billion a year on R&D — 16 percent of its turnover — and holds more than 10,000 patents worldwide.

Taken to extremes

Today, a significant part of that R&D work is focused on the commercialization of a new generation of lithography machines that use extreme ultraviolet (EUV) light in their operation. The new technology is required because the features of the latest chip generations are so small that conventional UV wavelengths can no longer provide sufficient definition. The barriers to its commercialization have been formidable, however.

EUV systems have to operate in a vacuum, for example, and the beams of ultra-short-wavelength light they use are extremely difficult to manage using conventional mirrors and lenses. After more than a decade of research and development in its own labs, ASML has now supplied EUV machines to a number of customers around the world. Volume production of chips using the new machines is expected to begin in 2018/2019.

ASML is not just a research-driven business, however. The best ideas are of little use to the industry if they can't be incorporated into reliable machines. That involves a high level of manufacturing expertise - and highly sophisticated supply chains. ASML built around 160 machines in 2016. While assembly and testing is conducted at the company's headquarters in Veldhoven, the vast majority of the components that make up its machines come from a network of 600 suppliers spread across the world.

Almost every machine we've ever built is still working today. And we have to ensure those machines keep running, and upgrade and adapt them as our customers' processes evolve.Yolanda van Norden
IMMERSIVE SCIENCE: ASML uses a process called immersion lithography in the manufacture of its semiconductors.

Coordinating the supply chains that support its manufacturing activities is an operation of considerable complexity. ASML has to ensure that the thousands of parts, subassemblies and modules that make up its machines arrive in time to enable their assembly. Then,once they’ve been thoroughly tested, the huge, delicate machines need to be partially dismantled for shipping to the end customer. ASML’s latest, largest machines require 20 trucks to transport and fill the holds of three Boeing cargo aircraft, says van Norden. Every stage of the logistics process has to be managed with great care to prevent shocks or temperature extremes that could damage their components.

The biggest supply chain challenges, however, arise once machines are in operation at customer sites. “Almost every machine we’ve ever built is still working today,” says van Norden. “And we have to ensure those machines keep running, and upgrade and adapt them as our customers’ processes evolve.”

Looking after its fleet of equipment in operation at customer sites requires sophisticated service logistics capabilities. “The requirements of our customers change over time,” explains van Norden. “When they introduce a new technology, the focus is on the performance of the process. Later it’s all about output and speed, and finally it’s about reliability and cost.” The eye-watering cost of a chip plant – a modern semiconductor fabrication facility can cost anything between $3 and $10 billion to build – means manufacturers need to keep their production lines running at full capacity to recoup their investment. They don’t want to wait any longer than necessary for spare parts when things go wrong.

For ASML, looking after its machines is further complicated because, while the company’s main operations are in Europe, its customers are concentrated in Asia and the U.S. “Our customers expect spare parts inventories to be held close to their plants, so equipment suppliers like us need warehouses and service engineers in those locations,” says van Norden. And ASML’s parts warehouses aren’t just storage facilities, they often include their own cleanroom facilities to allow components to be assembled and prepared prior to delivery to customers.

Continuous improvement

ASML's support for its customers isn't just about keeping machines running, however. Its customers also need those machines to continually evolve as new technologies become available and their own processes and requirements change. That means ASML is continually re-engineering its equipment, adapting and improving machines that may have been in service for many years. "We manage around 6,000 engineering change orders every year," says van Norden. "That means we need significant flexibility from our suppliers, and we need to be able to drive innovation through the supply chain to our customers." Overall, that effort involves 2,000 field engineers and 150,000 parts shipments every year.

For van Norden, who moved into her current role after many years in procurement, ASML's supply chain provides a uniquely broad perspective on the whole of the company's activities. "In the supply chain, you are in the center of your organization," she says. "You get a close-up view of product development, you get to see what's happening at supplier factories and customer sites. I'd advise anyone who really wants to understand a complex business to spend a couple of years working in the supply chain function, it really is a great learning curve." —  Jonathan Ward

Published: April 2018

Images: ASML