IEEE Solid-State Circuits Magazine - Spring 2016 - 21

memory density advanced in lockstep.
New operating systems and applications demanded more memory as well
as CPU cycles. The attractiveness of
DRAM technology brought new corporate and even governmental players into the marketplace. Cycles of
oversupply (brought about by overinvestment) and undersupply (as applications expanded to catch up) led to
dramatic price swings and periods
of industry profitability and loss. In
this difficult environment, companies
flourished and failed, and the 40-some
players in the mid-1980s eventually
dwindled to the three main DRAM manufacturers in the market today. One
of these early manufacturers-entering the early DRAM fray in 1978-had
its humble origins in the basement
of a dental office just off Cole Road
in Boise, Idaho. That company was
Micron Technology.
Early volatility in the DRAM business instilled a tenacious will to survive in this little DRAM manufacturer.
Early on, Micron adopted a strategy
of using state-of-the-art tools to fabricate high-volume, current-density
components, giving the company an
economic advantage over those competitors that left their high-volume
designs on older processes as they
pursued higher-density, leading-edge
parts (Figure 8).
In December 1983, the young
Micron company celebrated a milestone: shipping over one million 64-K
memory devices. Today, a single NAND
flash chip contains more memory bits
than Micron's entire shipments in
December of 1983.
Volatility in the DRAM industry
continued, with players exiting the
market during each downturn and
making rampant investments during
the upturns. Governments encouraged and subsidized entrants into
the markets-and bailed out debtridden companies as needed. During one of these downturns in 1998,
one of the biggest players, Texas
Instruments (TI), decided to throw in
the towel on DRAM manufacturing.
Eventually TI would structure a deal
with Micron to transfer its world-

Figure 8: A current-registered DRAM module. (Photo courtesy of Micron Technology, Inc.)

wide DRAM operations to Micron.
Thus, in a single deal, Boise-centered Micron was transformed into
a global semiconductor company,
with fabrication plants in the United
States, Japan, Singapore, and Italy.
The acquisition of TI's DRAM
business became the template for
Micron's survival and expansion
over the next 15 years. In 2002,
Toshiba would exit the commodity DRAM business, turning it over
to Micron. The demise of Qimonda
would present similar opportunities
for Micron. When Elpida faltered in
2013, Micron again stepped in.
As the number of DRAM players
has shrunk, the applications for
DRAM have expanded, and devices
have become specialized (Figure 9).

Figure 9: Hybrid memory cube devices
based on DRAM technology. (Photo courtesy of Micron Technology, Inc.)

firmware storage, it didn't find its
way into the memory hierarchy of
computing platforms in a big way.

Mercury tube delay lines gave way to metal
wire delay lines, which used the propagation
of a torsional wave down the wire as the
storage medium.
Low-power, high-performance, lowlatency directions multiplied by
numerous packaging technologies
have expanded the portfolios of
the DRAM manufacturers, making
for a very diverse US$40+ billion
industry [8].

Flash Forward
In the early 1980s, Dr. Fujio Masouka
of Toshiba developed a new type of
memory; it still relied on trapping
charge, but it trapped this charge
where it wouldn't drain away when
power was lost. This memory was
termed "flash" memory. While NOR
flash was rapidly adopted for use as

In fact, most often the contents of
flash memory were moved first to
DRAM, where CPU execution time
was much faster.
The "killer application" for flash
memories evolved in the mid-2000s
as NAND flash emerged, offering nonvolatility at a price per bit roughly
one-quarter that of DRAM (at that
time). Not suitable for use as main
memory by a CPU due to its high error
rate and limited endurance, NAND
flash was the perfect storage media to
replace small, low-density hard drives
in mobile, battery-operated products
(Figure 10). The killer application that
NAND enabled? The smartphone.

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Table of Contents for the Digital Edition of IEEE Solid-State Circuits Magazine - Spring 2016