In the chip manufacturing industry, there has always been a saying of "a piece of silicon, eight tons of water", is the water consumption of chip manufacturing really that big?
This is indeed true, and this water is not your average water! So how much water will be used?
Let's take a look at the water consumption of a typical chip manufacturing company. According to some publicly available data and reports from Intel, MediaTek, Samsung and other companies, their water consumption is as high as tens of millions to hundreds of millions of liters per day.
Samsung, for example, consumes 4 million to 5 million liters of water per day at its chip factory in Gyeonggi Province, South Korea, which is equivalent to the daily water consumption of 15,000 to 20,000 households. TSMC, on the other hand, needs to use 100,000 tons of ultrapure water every day to wash chips!
What is this water used for?
In fact, a large amount of water is required in multiple stages of chip manufacturing, such as wafer cleaning, etching, and film production.
Taking wafer cleaning as an example, it can be said that it is the most water-intensive part of the chip manufacturing process. The main purpose of wafer cleaning is to remove various contaminants generated by the wafer surface during processing to ensure the cleanliness of the wafer surface.
The reason for this is that wafer cleaning is not just one cleaning, but pre-cleaning, in which case the wafer is soaked in deionized water and cleaned with an ultrasonic cleaner or spray device to remove dissolvable organic matter and large particles of impurities on the wafer surface.
This is followed by a primary cleaning, which effectively removes both organic and inorganic matter from the surface. This is followed by post-processing, which also uses rinsing and deionized water immersion.
This is only one of the links in chip manufacturing, and then etching, in order to ensure the effect of etching, it is necessary to prevent the equipment from overheating, and the way to prevent overheating is to connect the external process cooling water.
However, the temperature of the medium used in the etching process must also be controlled, if the temperature of the medium is too high or unstable, it will lead to unstable etching quality and defective products, and the solution is to use process cooling water to control the temperature.
Water is also required for the film growth process, where some chemical solutions are used. Ultrapure water is also required for the preparation and use of these solutions.
In order to ensure the quality and performance of the film, the purity and stability of the chemical solution need to be ensured, so ultrapure water is the basis of choice.
Of course, the ultrapure water mentioned here is not ordinary water, and it requires a rigorous preparation process to obtain ultrapure water.
What is ultrapure water for chip manufacturing?
Pure water is actually a kind of specially treated water, which is divided into primary, secondary, tertiary pure water and ultrapure water according to different indicators.
The conductivity of tertiary pure water is usually less than 50 μS/cm (25°C), and a certain amount of dissolved solids and organic matter is allowed in the water, and there may be a high content of microorganisms, but this water is only suitable for general cleaning and industrial use.
The conductivity requirements for secondary pure water are a little higher, typically less than 10 μS/cm (25°C). The presence of lower levels of dissolved solids and organics in the water allows for the presence of moderate levels of microorganisms, but is also only suitable for general laboratory, cleaning, cooling, etc.
The conductivity of primary pure water is very strict, usually less than 1.0 μS/cm (25°C). The dissolved solids, organic matter, and microbial content in the water are very low. This water can be used in the electronics industry, pharmaceuticals, cosmetics production, etc., which are all fields with high water quality requirements.
Ultrapure water, as the name suggests, is a more demanding type of water, which is a highly pure water that has been deionized, degassed, and de-microbialized.
In terms of conductivity, it is required to be less than 0.055 μS/cm (25°C)! Dissolved solids, organic matter, and microorganisms are required to be completely free, and there are almost no impurities in this water except for water molecules, that is, water that has almost all atoms except oxygen and hydrogen removed.
And this water is used in large quantities in chip manufacturing.
Because the requirements of the manufacturing process are more complex, several processes such as pretreatment, reverse osmosis, ion-exchange, EDI system, polishing resin and terminal ultrafiltration are required. Moreover, it is necessary to control the parameters of each link, such as pressure, temperature, flow rate, etc., in order to maintain the quality and yield of ultrapure water.
Therefore, the chip plant usually adopts the central water supply system, which uses a set of devices to complete the preparation of ultrapure water, and then disperses the supply to the terminal that needs water.
And when this "pure" water passes through the processing equipment, his mission is also completed, and it becomes wastewater.
Wastewater from chip manufacturing companies
Because a variety of reagents, gases, and chemicals are used in the manufacturing process, the composition of the wastewater after production is quite complex.
For example, cleaning and etching plants generate acid and alkaline wastewater. Chemical vapor deposition and photoresist stripping processes produce wastewater with large amounts of organic solvents, such as acetone, methanol, ethanol, etc., which are biotoxic and difficult to biodegrade.
The coating and grinding process also produces heavy metal wastewater, which contains heavy metal ions such as copper, nickel, chromium, and lead. These heavy metal ions can be adsorbed and accumulated in living organisms, which is not only harmful to humans and marine organisms, but also accumulates over time.
Because of the complexity of the whole process, the wastewater may also contain other harmful components, such as fluoride, chloride, inorganic salts, etc.
Therefore, the wastewater generated after chip manufacturing must be treated reasonably and properly.
Generally, the pretreatment stage is carried out first: the suspended solids, oil and some precipitable substances in the wastewater are mainly removed. After that, the pH value is neutralized, and the pH value of the water is adjusted to a moderate level by using the acid-base neutralization reaction.
For heavy metal ions, they need to be precipitated and then eliminated with some sedimentation agent, or they need to be adsorbed and exchanged in wastewater with specific resins.
Organic wastewater can use microorganisms to degrade organic matter or completely decompose organic pollutants by generating strong oxidants.
Of course, in order to improve the appearance of wastewater, activated carbon adsorption, chemical oxidation, etc. will be used to effectively decolorize wastewater. Finally, it is ensured that the wastewater meets the discharge standards required by the local requirements.
Other challenges facing the chip industry in China
Of course, the large water consumption in chip manufacturing enterprises is only the tip of the iceberg of the problems faced by their development process.
In recent years, the production of chips in mainland China has been growing. From January to February 2024, the output of chips in mainland China reached 70.42 billion, a year-on-year increase of 59%, setting a new historical growth record.
However, despite the increase in production, the self-sufficiency rate of chips on the mainland is still low. The mainland government has set a goal of completing chip self-sufficiency by 2025, so that the self-sufficiency rate of domestic chips will reach 70%.
It is estimated that by 2027, the share of China's chip production capacity in mature processes will increase significantly from 30% in 2023 to more than 39%, which means that we have also entered the fast lane in the chip field.
The upstream participants in the mainland chip industry chain mainly include suppliers of raw materials such as silicon wafers, photoresists, and CMP polishing slurries. As we all know, due to the import restrictions and technical blockade of mainland chips in foreign markets, the mainland chip industry is facing considerable challenges in the supply chain.
The demand for talents in the smart chip industry is huge, but there is a certain gap in the supply of talents. This also puts forward the training requirements for professional specialties in the field of chip R&D for our education, so as to strengthen R&D and innovation, improve our independent innovation capabilities, and enhance the overall soft power.
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