Ultrapure water is water from which impurities have been removed to the utmost limit.

Ordinary water contains

・Minerals

・Fine particles

・Bacteria

・Organic matter, and more.

In semiconductor manufacturing, all of these become impurities.

Therefore, in ultrapure water,

・Ions

・Particles

・Organic matter

・Microorganisms, and more

are removed to the utmost limit.

In semiconductor manufacturing, hundreds of process steps are performed on a single wafer.

A cleaning step is always inserted after each process.

Reasons:

・Removing fine particles

・Removing chemicals

・Cleaning the surface

If cleaning is insufficient, it leads to

・Defects

・Short circuits

・Lower yield.

Leading-edge semiconductor factories use a very large amount of water.

Example:

Large fab → tens of thousands of tons per day

This is comparable to the water use of a medium-sized city.

For this reason, regions with abundant water resources are advantageous as factory locations.

Taiwan is the center of the semiconductor industry.

It is home to many semiconductor factories, including TSMC’s.

However, Taiwan is a region prone to water shortages.

During droughts, measures such as

・Restrictions on industrial water

・Emergency transport of water

have been taken in the past.

Water reuse is advancing in semiconductor factories.

Examples:

・Wastewater recovery

・Retreatment

・Reuse

Some leading-edge factories aim for a water recycling rate of 80% or more.

Ultrapure water is produced through multiple processes.

Main processes:

・Filtration

・Ion exchange

・Reverse osmosis (RO)

・Ultraviolet treatment

These produce water of extremely high purity.

Ultrapure water requires constant quality control.

The reason is that

even trace contamination can lead to

・Device defects

・Lower yield.

For this reason,

・Real-time water quality monitoring

・Particle measurement

and other measures are carried out.

Water resources are important when choosing a location for a semiconductor factory.

Requirements:

・A stable water supply

・High-quality water sources

・Water treatment infrastructure

For this reason, building factories in water-scarce regions can be difficult.

Japan has relatively abundant water resources.

This gives it favorable conditions for semiconductor manufacturing.

Examples:

・TSMC’s Kumamoto factory

・Rapidus in Hokkaido

Water resources are important infrastructure for the semiconductor industry.

Semiconductor companies are also working to reduce water use.

Examples:

・More efficient cleaning processes

・Water recycling

・New cleaning technologies

The aim is both environmental responsiveness and cost reduction.

Demand for semiconductors will continue to increase.

For this reason, water issues will become an important challenge for the semiconductor industry.

Going forward,

・Reducing water use

・Reusing water

・Managing water resources

will become important.

・Semiconductor manufacturing uses large amounts of ultrapure water

・Wafer cleaning is an important process

・Leading-edge factories use tens of thousands of tons of water per day

・Water shortage problems have occurred in Taiwan

・Water recycling technology is advancing

・Water resources affect factory location

1.Why is ultrapure water needed in semiconductor manufacturing?

2.What are the main processes in which semiconductor factories use large amounts of water?

3.Why do water resources affect the location of semiconductor factories?

 

Column Supervisor: Koji Kakumoto (President, OTIS Co., Ltd.)

After studying abroad and working in planning and development at a trading company, he joined OTIS Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as President, working to drive business growth and strengthen the organization.

 

This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.