Cleaning optics for  Water Steppers

In 1993, no WASTE systems received an urgent call from ASM Lithography’s development department in the Netherlands. They faced a critical issue with the lenses in their wafer steppers. Imagine these lenses as a complex telephoto lens assembly, consisting of 28 carefully balanced glass components. Each lens plays a vital role in achieving the high-resolution imaging of intricate electric circuits printed on silicon wafers. After exposure, the wafers undergo a meticulous development and etching process, repeated around 28 to 36 times. This method is essential for fabricating memory chips and processors, which are built like skyscrapers with multiple precisely linked levels.

However, despite being treated with ultra-pure helium, the lenses became contaminated with an oil film, causing production to plummet and resulting in a high rejection rate of chips. ASM Lithography found itself on the brink of bankruptcy.

To resolve the crisis, the defective lenses had to be removed and replaced—a painstaking process since the lenses were sensitive to vibrations, which could disrupt their delicate balance. Rebalancing alone took three months! Meanwhile, a team of about 40 specialists at Carl Zeiss in Oberkochen was working tirelessly to find a solution.

The breakthrough came unexpectedly simple: flushing the lenses with ozone gas. This “simple” operation had a dramatic and immediate impact. The lenses performed even better than before, surpassing the quality that Carl Zeiss could achieve! No longer did they need to transport defective lenses around the world.

Contamination had gradually decreased the transmission rate by up to 40%. Thanks to the ozone treatment, a lens valued at 2 million euros was revitalized, breathing new life into it. This method was first implemented at Micron Technology in BOISI the U.S., where 35 machines were struggling to meet specifications. Once management authorized the cleaning of a single machine using this new method, the results astonished everyone. The management declared, "I want all those wafer steppers cleaned—critical and non-critical!"

Despite uncertainties about guarantees and unforeseen future effects, management insisted that all units undergo this ozone treatment. The following year, Micron became the most efficient semiconductor manufacturer in the world.

The ozone treatment resulted in at least four significant improvements: a minimum of 30% faster exposure time, 30% better transmission, 30% less product failure, and 30% better resolution. The impact on microprocessor pricing was profound.

Thanks to the innovations driven by ASM Lithography, they remain leaders in the field. The gas quality has since evolved, now utilizing a smarter method with oxygen.

Without this technological advancement, our digital landscape would be unrecognizable. The semiconductor industry—and indeed, the modern world—owes a great deal to this pivotal breakthrough.

Epilogue ASML project.

Without the application of this technology, the world would look completely different. We wouldn’t have smartphones, powerful computers, or even modern medical equipment. This breakthrough is not just a step forward; it is the crucial development that has transformed the semiconductor industry. It’s almost unimaginable to think about what our daily lives would be like without the innovations that emerged from this revolutionary technology. We would be stuck in an era of limited possibilities, where progress stagnates and connectivity is lacking. The impact cannot be underestimated; this technology has laid the foundations for the digital world as we know it today.