The Chip Patterning Machines That Will Shape Computing’s Next Act
upstart writes:
When we talk about computing these days, we tend to talk about software and the engineers who write it. But we wouldn't be anywhere without the hardware and the physical sciences that have enabled it to be created-disciplines like optics, materials science, and mechanical engineering. It's thanks to advances in these areas that we can fabricate the chips on which all the 1s and 0s of the digital world reside. Without them, modern computing would have been impossible.
Semiconductor lithography, the manufacturing process responsible for producing computer chips, has 70-year-old roots. Its origin story is as simple as today's process is complex: the technology got its start in the mid-1950s, when a physicist named Jay Lathrop turned the lens in his microscope upside down.
Lathrop, who died last year at age 95, is scarcely remembered today. But the lithography process he and his lab partner patented in 1957 transformed the world. Steady improvement in lithographic methods has produced ever-smaller circuitry and previously unimaginable quantities of computing power, transforming entire industries and our daily lives.
[...] Lathrop named the process photolithography-printing with light-and he and Nall filed for a patent. They delivered a paper on the topic at the annual International Electron Devices Meeting in 1957, and the Army awarded him a $25,000 prize for the invention. Lathrop bought his family a new station wagon with the money.
[...] But the approach wasn't practical as chip features got still smaller. By the late 1970s, scanners began to be replaced with steppers, machines that moved light in discrete steps across a wafer. The challenge with a stepper was to move the light with micron-scale precision, so that each flash was perfectly aligned with the chip. GCA, a Boston-based firm that had its origins in spy balloons, devised the first stepper tool, reportedly on the advice of Texas Instruments executive Morris Chang-later the founder of TSMC, which is today the world's largest chipmaker.
[...] The decline of America's lithography industry coincided with a dramatic leap forward in the field's technological complexity. Visible light-which has a wavelength of several hundred nanometers-was by the 1980s too broad a brush with which to paint the smallest transistors. So the industry shifted to using new chemicals like krypton fluoride and argon fluoride to create deep ultraviolet light, with wavelengths as low as 193 nanometers. By the early 2000s, after this ultraviolet light itself proved too blunt a tool, lithography machines were created that could shoot light through water, creating a sharper angle of refraction and thereby allowing more precision. Then, after this "immersion" lithography proved insufficient for the finest features on a chip, lithographers began using multi-patterning, applying multiple layers of lithography on top of one another to produce yet more precise patterns on silicon.
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