In 1955 Jules Andrus and Walter L. Bond at Bell Labs began adapting existing photolithographic (also called photoengraving) techniques developed for making patterns on printed circuit boards to produce much finer, more intricate designs on silicon in wafers using Frosch and Derick's silicon-dioxide layer. (1955 Milestone) After applying a photosensitive coating or "resist" on the layer and exposing the desired pattern on this coating through an optical mask, precise window areas were defined in the layer and opened by chemical etching where unexposed resist had been washed away. Impurities were diffused through these openings into the underlying silicon to establish the zones of n-type and p-type silicon needed in semiconductor devices.
In an early attempt to miniaturize electronic circuits in 1957, Jay Lathrop and James Nall of the U.S. Army's Diamond Ordnance Fuse Laboratories in Maryland patented photolithographic techniques used to deposit thin-film metal strips about 200 micrometers wide to connect discrete transistors on a ceramic substrate. They also used these techniques to etch holes in silicon dioxide to fabricate diode arrays. In 1959 Lathrop joined Texas Instruments, working for Jack Kilby, and Nall went to Fairchild Semiconductor.
Following up on this pioneering work, Jay Last and Robert Noyce built one of the first "step-and-repeat" cameras at Fairchild in 1958 to make many silicon identical transistors on a single wafer using photolithography. In 1961 the David W. Mann division of GCA Corporation was the first firm to make commercial step and repeat mask reduction devices (photo-repeaters). Photolithography remains an essential step in semiconductor manufacturing today, with feature sizes below 0.1 micrometer becoming commonplace.
Andrus, Jules. "Fabrication of Semiconductor Devices," U.S. Patent No. 3,122,817 (Filed August 15, 1957. Issued March 3, 1964)
Andrus, J. and Bond, W. L. "Photoengraving in Transistor Fabrication," in F. J. Biondi et al, eds., Transistor Technology, Vol. III (Princeton, NJ: D. Van Nostrand, 1958) pp. 151-162.
Lathrop. Jay W. and Nall, James R. "Semiconductor Construction," U. S. Patent No. 2,890,395 (Filed October 31, 1957. Issued June 9, 1959)
Nall, J. R. and Lathrop, J. W. "Photolithographic Fabrication Techniques for Transistors Which Are an Integral Part of a Printed Circuit," IEEE Transactions on Electron Devices, Vol. 5, No. 2 (April 1958), p. 117.
Prugh, T.A., Nall, J.R., Doctor, N.J. "The DOFL Microelectronics Program" Proceedings of the IRE, Vol. 47, Issue 5 (May 1959) pp. 882-894.
Lathrop, Jay W. (DOFL, TI) an oral history (2009) Transcript in process
Noyce, Robert. Electrical Engineer, an oral history interview conducted in 1975 by Michael Wolff, IEEE History Center, Rutgers University, New Brunswick, NJ, USA.
Lathrop, Jay W. Electrical Engineer, an oral history conducted in 1996 by David Morton, IEEE History Center, Rutgers University, New Brunswick, NJ, USA.
Henderson, Rebecca "Of Life Cycles Real and Imaginary: The Unexpectedly Long Old Age of Optical Lithography" Research Policy, 1995, Vol. 24, pp 631-643.
Burbank, Daniel P. "The Near Impossibility of Making a Microchip," American Heritage of Invention & Technology, Vol. 15, No. 2 (Fall 1999) pp. 44-51.