Power semiconductors are the key to restoring Japan's semiconductor industry

Japan's semiconductor industry began in the 1950s. By the 1980s, the country's reputation for manufacturing semiconductors had become firmly established all around the world, however, the industry began taking a downward dive with the 1986 Arrangement between the Government of Japan and Government of the United States of America concerning Trade in Semiconductor Products, and has been stagnant since the 2000s. Meanwhile, with the COVID-19 pandemic, unstable world affairs and other factors having an impact, economic security risk is high. In order to keep up with rapid digitalization and carbon-neutral goals, the importance of semiconductors and information processing technology is greater than ever.

Semiconductors play a crucial role in digitalization and information technology. As such, in May 2022 the Japanese government added semiconductors to the list of designated Specified Critical Products in the Economic Security Promotion Bill. This list comprises a total of 11 items which have been designated as key to economic security. Regarding semiconductors, the Ministry of Economy, Trade and Industry (METI) allocated 368.6 billion yen in the second supplementary budget for FY2022, and in the supplementary budget for FY2023, 1,545 billion yen was allocated for subsidies to boost semiconductor production capacity. In other words, nearly 2 trillion yen has been injected in the semiconductor industry over the past two years.

Semiconductors include the widely-known microcontrollers, memories, and so on, but one device garnering attention as the key to realizing a carbon-neutral society and restoring Japan's semiconductor industry is the "power semiconductor." In the power semiconductor market, Japan is one of the three major players along with the U.S. and Europe, with a global market share of around 26%, therefore its presence is certainly not small.
Incidentally, Mitsubishi Electric remains the top Japanese company, accounting for about 30% of the abovementioned approximately 26% (METI's "Semiconductor and Digital Industry Strategy" June 2023). In light of this fact, we spoke with Mr. Koichiro Noguchi of Mitsubishi Electric Power Device Works about these "power semiconductors" that are the focus of so much attention.

What are power semiconductors anyway?

There are two types of materials: conductors, which conduct electricity, such as metals, and insulators, which do not conduct electricity, such as rubber and wood. A "semiconductor" is a material that either conducts or does not conduct electricity depending on conditions such as the application of voltage, light, or heat.

We all use power semiconductors everyday

Power semiconductors are used in many everyday things, including household appliances such as air conditioners and refrigerators, as well as railway vehicles, hybrid/electric vehicles, and elevators. They are also used in places we don't often see, such as industrial robots used in factories, medical devices, solar and wind power generation, and power distribution equipment.

1. *1A module is a power semiconductor that combines multiple power semiconductors into a single package.
2. *2FY2021 results, based on Mitsubishi Electric's research

Mitsubishi Electric's power semiconductors are also very compatible with vehicles. For example, the first power semiconductor to be equipped in a Japanese-made hybrid car was manufactured by Mitsubishi Electric. Since then, the company's power semiconductors have been equipped in other hybrid and electric vehicles (EVs).

Also, there are two main usages for power semiconductors in railway vehicles. The first is to operate the motor, just in the same way as for EVs. The second is in a device that supplies power for the railway car's air conditioning, lighting and so on. Power brought into the car from the power lines need to be converted to a voltage and frequency suited to actual use, and power semiconductors are used to perform this conversion. Mitsubishi Electric has worked on many railway vehicles in Japan and our power semiconductors are used in these.

Strengths of Mitsubishi Electric's power semiconductors

Mitsubishi Electric first began developing power semiconductors in the 1950s. In 1958, the company developed Japan's first semiconductor for power (i.e. power semiconductor), therefore it has a long history of equipping semiconductors in electric engines and is today known as one of the leading power semiconductor companies.

SiC (silicon carbide) as an alternative power semiconductor material to Si (silicon)

In power modules, semiconductor chips are fabricated on a thin, flat disc called a wafer, multiple chips are fitted, metal wires are attached, and then everything is packaged and sold as a single module. Currently, most wafers are made of Si (silicon), but power semiconductors use a material called SiC (silicon carbide).

1. *3SiC-MOSFET module with built-in SBD "FMF800DC-66BEW." Compared with Si power module "CM600DA-66X."

How do SiC power semiconductors affect the devices in which they are installed?

The strengths of Mitsubishi Electric's SiC power semiconductors include the essential compound semiconductor technology, chip technology, and module technology, as well as rich market achievement based on these technologies.

Mitsubishi Electric began developing SiC power semiconductors in the early 1990s. In 2010, the company released "Kirigamine," the world's first room air conditioning unit using a SiC power semiconductor. In 2015, it has also developed a main circuit system using the "full SiC power module^*8" for the Tokaido bullet train line. It was the world's first run test using a full SiC power module, and in July 2020, the bullet train N700S commenced operation fitted with this module.

1. *8A power semiconductor that uses SiC for both the transistor and diode parts.

1. *9In elements with withstand voltage performance of 1500 V or higher; based on Mitsubishi Electric's research as of the PR announcement on September 30, 2019.

SiC power semiconductors promising to be a driving force for GX

In July 2022, the Green Transformation (GX) Implementation Council, chaired by Prime Minister Kishida, was formed, and in February 2011, the Cabinet approved the Basic Policy for GX Realization. GX represents a major shift from the fossil energy-centered industrial and social structure that has been mainstream since the Industrial Revolution to a clean energy-centered one. SiC power semiconductors are absolutely indispensable in order to achieve GX in a sustainable way. In addition, METI established new energy conservation standards for residential air conditioners in 2022, which call for up to 35% increase in energy consumption efficiency during cooling by 2027. For this reason, attention is bound to gather around SiC power semiconductors in this domain too.