Stepper

The stepper revolutionized semiconductor manufacturing by solving a fundamental problem: as chip features shrank, the optical systems required to print them became impossibly expensive if applied to entire wafers. The solution was elegantly economical—reduce a circuit pattern onto one chip at a time, then step to the next position and repeat.

GCA Corporation introduced the DSW 4800 in 1978, the first commercially successful wafer stepper. The system used 10x reduction optics and a Zeiss lens with 0.28 numerical aperture to project circuit patterns onto 10mm × 10mm fields. A laser interferometer controlled the wafer stage with nanometer precision, allowing alignment between the mask and wafer. The list price was $450,000—a fortune, but dramatically cheaper than full-wafer exposure systems with equivalent resolution.

The development traced to IBM's empirical work proving that reduction stepping could achieve the overlay accuracy that chip manufacturing demanded. GCA's stepper was publicly introduced at the European Microcircuit Engineering conference in Paris in September 1977, with the beta unit going to IBM. The technology worked: steppers demonstrated much lower defect rates and significantly better overlay performance than Perkin-Elmer's projection aligners, which had dominated the previous generation.

But the path from innovation to market dominance was not linear. Initial throughput was low—around 60 four-inch wafers per hour—compared to projection aligners. The 256K DRAM generation would prove the decisive moment. When feature sizes crossed below one micron, only steppers could deliver the resolution. The technology that seemed like an expensive niche tool became the only viable option.

GCA's triumph was brief. In 1980, Nikon introduced the NSR-1010G, the first commercial stepper in Japan, with higher-resolution optics. Japanese competition intensified. By the late 1980s, Nikon and Canon had captured the market. GCA's operations were dissolved in 1993 when General Signal could not find a buyer. The intellectual property eventually transferred through Integrated Solutions to Ultratech. The steppers that GCA invented to print microprocessors were manufactured by competitors using descendants of GCA's own technology.