chip graffiti
n. Artwork, initials, or some other non-functional design etched into the upper metallic layers of a silicon chip.
Examples
1999
Moose Boy turned up on a Motorola RF integrated circuit designed for the Nokia 5190 handset. For years, chip designers tucked such tiny drawings in unused space on the prototype, the master from which others are produced. In these days of compressed production cycles, smaller circuits, overworked engineers, and more automated production, however, chip graffiti has become a dying art.
—Mike Dolan, “Chip Fab,” Wired, November 01, 1999
1999 (earliest)
Remember the story last year that a version of Intel Corp's Pentium chip had escaped from the plant with the words "bill sux" inscribed on it and released onto the market for use in tens of thousands of PCs? That story ultimately turned out to be a hoax (CI No 3,464), and the picture of the supposed graffiti that was widely passed around the net was thought to have been faked using Adobe PhotoShop. Now, however, there is a web site of real chip graffiti, available at the "silicon zoo" section of the Molecular Expressions site (http://micro.magnet.fsu.edu/galleria/index.html).
—“Chips from the clean room are covered in graffiti,” Computergram International, February 12, 1999
Notes
The above Wired article also mentions that a company called Chipworks maintains a gallery of chip graffiti (which it calls silicon art).