During the early 1990s, half-micron lithography was demonstrated in 16
Mb DRAM fabrication. Utilization of this capability for CMOS logic dev
ices within IBM followed with a trio of programs, each with different
performance, density, feature list, and schedule. The first version me
lded 3.3/3.6-V 16Mb DRAM MOSFET devices with an improved version of an
existing dense, planar, reliable multilevel backend-of-line (BEOL) me
tallization and wiring technology. Since it was built directly from ex
isting technologies, it was released quite quickly. A 3.3-V follow-on
technology was added several months later. This logic offering added a
local interconnect and a faster device. A second follow-on achieved g
reater speed improvement, calling upon a 2.5-V power supply and very t
ight channel-length control to obtain performances 50% above previous-
generation standards, at lower power.