Photomask projection aligner

The photomask projection aligner revolutionized semiconductor manufacturing by eliminating contact between mask and wafer—a change that literally made the modern integrated circuit industry possible. Before 1973, photomasks touched wafers during exposure, causing defects that limited yields to around 10%. Perkin-Elmer's Micralign changed everything.

The adjacent possible required precision optics and alignment systems. Contact aligners worked by pressing photomasks directly against silicon wafers, transferring circuit patterns through photolithography. But contact meant contamination: particles trapped between mask and wafer created defects, and repeated use damaged expensive masks. The industry desperately needed separation.

Perkin-Elmer introduced the Micralign in 1973—the first production projection aligner. Instead of touching the wafer, the mask was held entirely separate, and the circuit pattern was projected through a complex optical system. The Chip History Center later noted that this invention 'literally made the modern IC industry.'

The technical challenges were formidable. The optical system had to project images at one-to-one magnification with sub-micron precision across the entire wafer. Alignment between successive mask layers required positioning accuracy that seemed impossible for industrial equipment. But the benefits were transformative: yields improved from perhaps 10% to about 70%, driving chip prices down dramatically.

Canon followed in 1973 with the PLA-300, Japan's first contact mask aligner, while continuing to develop projection systems. But the next revolution was already brewing. In 1975, IBM's Wilczynski demonstrated step-and-repeat printing—exposing chips one at a time rather than the whole wafer, using 10:1 reduction optics.

GCA commercialized this approach in 1978 with the DSW 4800, the first wafer stepper. The stepper's resolution wasn't better than advanced projection aligners, and productivity was worse. But defect density dropped dramatically: 1-micron dust on a 10:1 reduction reticle became only 0.1 microns on the wafer—invisible rather than fatal.

Path dependence shaped the competitive landscape. Nikon released the NSR-1010G stepper in 1980, achieving 1-micron resolution with 5x reduction instead of 10x. This higher resolution knocked GCA from leadership. GCA's decline culminated in dissolution by 1993, its intellectual property eventually acquired by Ultratech in 1998. Japanese and eventually Dutch (ASML) companies would dominate the lithography industry that Perkin-Elmer's 1973 innovation had transformed.