Press release

Renesas Electronics Develops Low-Power Technology for Embedded Flash Memory Based on SOTB™ Process to Enable Energy Harvesting and Eliminate Need for Batteries

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Renesas Electronics Corporation (TSE: 6723), a premier supplier of
advanced semiconductor solutions, today announced the development of new
low-power technology for use in embedded flash memory based on a 65
nanometer (nm) SOTB™ (Silicon On Thin Buried Oxide) process. Available
with 1.5 MB capacity, it is the world’s first embedded 2T-MONOS (2
Transistors-Metal Oxide Nitride Oxide Silicon) flash memory based on
65nm SOTB technology (Note 1). With the addition of a new circuit
technology that reduces the power consumption of the peripheral circuits
on flash memory, Renesas achieves read energy as low as 0.22 picojoules
per bit (pJ/bit) at an operating frequency of 64 MHz – among the world’s
lowest levels for embedded flash memory on an MCU. The newly developed
low-power technology for peripheral circuits comprises circuit
technology that (1) reduces energy consumption when sensing data in
memory and (2) reduces the amount of transmission energy consumed when
read data is transmitted to an external destination. Together, these
advances substantially reduce energy consumption when reading data from
the memory.

Renesas presented these results on June 12 at the 2019 Symposia
on VLSI Technology and Circuits
in Kyoto, Japan, June 9-14, 2019.

The new SOTB-based technology has already been implemented in the
Renesas R7F0E embedded controller, which is intended specifically for
energy harvesting applications. Renesas’ exclusive SOTB process
technology dramatically reduces power consumption in both the active and
standby states. Power consumption in these two states had previously
been a tradeoff: Lower power consumption in one generally meant higher
power consumption in the other. The new technology substantially reduces
power consumption when reading data from the flash memory. In contrast
to non-SOTB 2T-MONOS flash memory, which requires a memory read current
of about 50 µA/MHz, the read current is reduced to a mere approximately
6 µA/MHz. This is equivalent to a read energy level of 0.22 pJ/bit, one
of the lowest levels for embedded flash memory on an MCU. The new
technology also contributes greatly to the achievement of a low-active
read current of 20 µA/MHz on the R7F0E, among the best in the industry.

Key Features of the Newly Developed Embedded Flash Memory Technology:

Low-power 2T-MONOS flash memory ideally suited to the SOTB process

The 2T-MONOS embedded flash memory using the SOTB process has a
two-transistor structure comprising electrically isolated elements.
Unlike a single-transistor structure, there is no need for negative
voltage during read operation, and this reduces power consumption when
reading data. In addition, compared with other memory processes, MONOS
uses fewer masks during the production process, and it is possible to
store data with a discrete charge-trapping scheme. This enables low
power consumption and high rewrite reliability without increasing the
production cost.

Sense amplifier circuit and regulator circuit technology for
ultra-low energy consumption

Most of the energy consumption during memory read operations occurs
during sensing operation to identify data and transmit operation to
output the identified data to an external destination. To address the
former, a single-ended sense amplifier substantially reduces the bit
line pre-charge energy during sensing operation, employing a new
charge-transfer technology that boosts pre-charging speed and energy
efficiency. In addition, a newly developed regulator circuit technology
uses leak monitoring to perform optimal intermittent control of the
sense amplifier’s reference voltage which consumes energy in a constant
manner. These advances make it possible to speed up sensing operation
while substantially reducing energy consumption.

Circuit technology that dramatically cuts data transmission energy

One characteristic of the SOTB process is minimal variation in the
transistor threshold (Vth), and the newly developed circuit technology
takes advantage of this to achieve data transmission using an extremely
small voltage amplitude. This advance results in a substantial decrease
in the transmission energy consumed when read data transmitted to an
external destination.

By helping to make endpoint devices more intelligent, Renesas is
accelerating the trend toward a “smart society.” Renesas considers
energy harvesting systems, which do not need batteries and therefore
never require battery replacement, to be an essential step toward this
goal, and plans to continue developing technology that will help to
realize an environmentally friendly smart society.

(Note 1) MONOS: Metal-oxide-nitride-oxide-silicon. Renesas has achieved
a substantial track record with MONOS technology over the past 20 years
in EEPROM, secure MCU, and other products. The MONOS technology is used
in the embedded flash memory of Renesas MCUs.

About Renesas Electronics Corporation

Renesas Electronics Corporation (TSE:
) delivers trusted embedded design innovation with complete
semiconductor solutions that enable billions of connected, intelligent
devices to enhance the way people work and live. A global
leader in microcontrollers, analog, power, and SoC products, Renesas
provides comprehensive solutions for a broad range of automotive,
industrial, home electronics, office automation, and information
communication technology applications that help shape a limitless
future. Learn more at

(Remarks). SOTB is a trademark of Renesas Electronics Corporation. All
names of products or services mentioned in this press release are
trademarks or registered trademarks of their respective owners.