January 29, 2022

CHICAGO PIXELS

SEMICONDUCTOR RESEARCH CENTER

Pursuing the Ultimate – A Sunresin Perspective on Purity

In nature, substances appear in the form of mixtures. This rule applies to our most common, simple, and indispensable sunlight, air, and water. The sunlight splits into seven colors namely violet, indigo, blue, green, yellow, orange, and red. Air is mainly composed of nitrogen, oxygen, argon, carbon dioxide and some other substances. The water we consume in our life also dissolves many ions such as calcium, magnesium, sodium, potassium, carbonate, bicarbonate, sulfate, and chloride ions.

However, in industrial applications, we only need and use a specific property of a specific substance, that leads to the need to separate the specific components from the mixtures. In order to maximize the use of the specific component, the rule is simple, that’s basically “The Purer The Better”. Therefore, the development history of industrial civilization is accompanied by the progress of separation and purification technologies.

The wave of new technological revolutions set off in the second half of the 20th century is changing human life in unprecedented ways. Among them, the most noticeable are information technology and modern biotechnology, whose rapid development has led to much higher requirements for the separation technologies.

In the semiconductor industry, there is the so-called “Moore’s Law”, according to which the number of transistors in a dense integrated circuit (IC) doubles about every two years, and the performance of the processor will also be doubled. In other words, for the same function to be realized, the space is reduced by half. Due to the continuous improvement of the precision of “lithography”, the component density and circuit density on the silicon chip have been greatly improved. With the increase in density, more stringent requirements have been placed on the material performance as the bearer of integrated circuits or chip space. This improvement of material properties is by improving purity. For the tens of billions of transistors on a chip the size of a fingernail, any small purity defect may lead to irregular heat dissipation, conductivity, or short circuits that mean disasters for the chip.

The purity of electronic grade polysilicon is required to reach 99.999999999%. Higher purity means more complicated production and refining processes. The 11N purity is equivalent to the total impurity of the weight of a 1 Euro coin in 5,000 tons of electronic grade polysilicon.

In the chip manufacturing process, it is necessary to constantly rinse with water. The water used is not pure, but “Ultra-Pure Water“, with a resistivity close to the limit value of 18.3 MΩ*cm (25°C). Except for water molecules, almost no impurities, bacteria, viruses, chlorinated dioxins or other organic substances are allowed. Of course, the mineral elements the human body needs are also unacceptable. The impurity content of Ultrapure Water is controlled at the ppb (Parts Per Billion) level. In chip manufacturing, impurities in the water may contaminate the chips during the washing process, so the control of impurities in the water is very, very strict.

Over the past 30 years, biotechnology, represented by genetic engineering, has achieved rapid development and has also put forward an urgent need for optimization of its downstream process, that is, the separation and purification technology of biotechnology products.

Different from traditional chemical separation and purification, the separation and purification of biotechnology products has the following characteristics:

(1) The separation object has specific biological activity, and the separation and purification process may be inactivated due to improper process design.

(2) The separation object often exists in a dilute solution containing many impurities with very similar properties, adding to the difficulty.

(3) From the perspective of hygiene and safety, genetic engineering products for treatment have extremely high purity and identity requirements, high requirements for the removal rate of harmful impurities, and stricter requirements for separation equipment and separation media.

In addition, the development of high techs in materials science, environmental science, resources and new energy has also put forward higher and higher requirements for purity. For example, silicon tetrachloride required in the production of optical fibers has high purity requirements, in which the content of hydrogen-containing compounds is required to be less than 4×10-6, and the content of metal ions is required to be less than 2×10-9.

There is an important concept in economics, margin, meaning “the last one added.” Marginal cost is the added cost of producing one more product. Marginal revenue is the revenue added by producing one more product. Due to the “law of diminishing marginal returns”, when the production volume reaches a certain level, if it continues to increase, the return per product will gradually decrease. Similarly, this time also corresponds to the increase in marginal cost, that is, if one more product is produced, the cost per product will gradually rise. Therefore, under the conditions of a perfectly competitive market, when the marginal cost and the marginal revenue are equal, the output is the optimal output. The benefit from this output is the maximum benefit, and at the same time, it is also when the cost is the lowest.

Based on this, we put forward a concept of “marginal purity”, that is, the last little increase in the purity of the material greatly improves its value, and sometimes even completely changes the physical properties of the material, which also determines its commercial value. In other words, the number of 9 in the purity of 99.9999…% and the size of N in the impurity content a×10-n determine its value. For example, high-purity gallium is metallic gallium with purity higher than 99.999% and total impurity content lower than 10-5. According to the purity, it can be divided into 5N (purity of 5 9s, that is, 99.999%), 6N, 7N, and 8N. High-purity gallium is the key basic raw material for the production of semiconductor materials. Among the four grades of products, 6N and 7N products account for more applications. 6N high-purity gallium is mainly used in the fields of LED lighting and photovoltaic cells, and 7N high-purity gallium is mainly used In the field of integrated circuits and microelectronics. One more 9, and the applications are completely different.

Separation has played a key and decisive role in production costs and product quality in many applications. According to statistics, for a typical chemical enterprise, the investment in the separation process generally accounts for 1/3 of the total investment. In the production process of some genetic engineering products, the cost of separation and purification accounts for as much as 90% of the total production cost. (according to Zhu Jiawen and Wu Yanyang, “Separation Engineering”).

There are various methods and technologies for separation and purification, and the adsorption technology that Sunresin is engaged in is one of them. Modern industry, information technology, life sciences, environmental protection, and new energy sciences have increasingly higher requirements for purity and a broad downstream application space, making the Sunresin Technology a pioneer in the innovation of separation technologies globally.

Sunresin, driving the innovation.

submitted by /u/sunresin
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