The 1 µm process refers to the manufacturing technology that came into use at leading semiconductor manufacturers from the second half of the 1980s onward. It is the last node whose designation is still commonly written in micrometers.
Exposure changed from the g-line at 435.83 nm to the i-line of the mercury-vapor lamp at 365.01 nm. According to the Rayleigh criterion, a shorter wavelength directly provides higher resolution without requiring a fundamental change in the optical principle – at the cost of lower light output and therefore longer exposure times.
At a channel length of around one micrometer, the hot-carrier effect becomes a problem: the electric field strength at the drain becomes so high that individual electrons gain enough energy to enter the gate oxide. They become trapped there, shift the threshold voltage and cause the transistor characteristics to drift over its operating lifetime. The solution is the lightly doped drain (LDD): an additional, more lightly doped region between the channel and drain that spreads the electric field over a greater distance. It is formed using oxide or nitride spacers on the sides of the gate.
At this node, CMOS is the rule rather than the exception. Wafer diameter increases to 150 mm.
Processors manufactured in 1 µm (selection):
- Intel 80386 (later manufacturing generations)
- Intel 80486 (1989), exceeding one million transistors for the first time