TOKYO OHKA KOGYO CO., LTD. (TOK) provides chemical products, such as photoresist, and equipment for semiconductors and displays.

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Environmental Activities

Corporate Social Responsibility

Promotion of recycling, managing chemical substances,
and approaches toward energy saving.

Creating New Environment Value through Business Activities

As introduced in the Special Feature (pages 30–31), TOK continues to contribute to solutions for the worsening problem of climate change through the stable supply of g-Line and i-Line photoresists for power semiconductors, for which it has the world’s top share*1. Recently, the Company has focused on the following R&D projects to provide new environmental value in the future.

*1 Share of sales volume for 2017 (Source: Fuji Keizai’s “Whole View of Photo-functional Material and Product Market 2018”)

Development of “Chemical Looping” Energy Recycling Systems

The Company recycles some of the organic solvent effluents generated in its manufacturing processes, and combusts and detoxifies resinous residues before emitting them. Now we are focusing on developing a chemical looping system for reducing the SOx and NOx generated in this process and recovering the CO2. Currently, we are promoting joint research with research institutions such as universities into SOx/NOx reduction and CO2 recovery. Going forward, we will work on conversion to renewable energy and CO2 conversion (turning CO2 into other chemical substances to make it harmless) in relation to the system.

Development of High-heat-resistant Photoresists for Next-generation Power Semiconductors

The power semiconductor market is projected*2 to grow at an average annual rate of 6.7% through 2025 and reach $29.9 billion by 2025, a figure that is roughly 1.7 times higher than 2017. SiC (silicon carbide) power semiconductors, regarded as a leading next-generation power semiconductor, greatly improve the electric power efficiency of electric vehicles, solar power generation and power sources of industrial machinery, and are expected*2 to see a compound annual growth rate of 30% and reach $2.5 billion by 2025, or about 8.2 times larger than in 2017. SiC power semicon­ductors are currently produced using conventional i-Line photoresists with lithography, etching, and high-temperature treatment processes. In this field, TOK is developing high-heat-resistant photoresists that will reduce the number of production processes and increase pattern precision. By combining high-heat-resistant resins with conventional i-Line photoresist technologies, this product features both high heat resistance and high resolutions. With this product, TOK will be able to contribute more to solutions for climate change through next-generation power semiconductors.

*2 Source: Yano Research Institute “Survey on Global Power Semiconductor Market (2018),” published on January 15, 2019

Black Resist

Color filters are essential to the operation of color LCDs. The filter has four colors: red, green, blue and a black matrix. Chrome is normally used to form the black matrix. However, we have eliminated chrome, which is a source of pollution, by replacing it with a black resist.

We have positioned the black resist as one of our strategic products and continue to work on developing black resist products.

Structure of a color filter

*The black matrix is the black border of the lattice containing red, green and blue squares. This black matrix is used to produce an image with greater contrast.

Spinless®

Normally, an LCD glass substrate is coated using the spin process, a method in which centrifugal force is used to apply photoresist evenly to a substrate. In this process, a substrate must be spun at high speed after a drop of photoresist is placed in the center. However, much of the photoresist simply flies off the substrate and is lost. Additionally, spinning substrates consumes a lot of electric power. Another problem is the growing size of these substrates, which makes them more difficult to spin.

To solve these problems, we developed the Spinless® coating technology. Instead of spinning substrates, this technique applies a uniform coating of photoresist by scanning the substrate surface with a slit nozzle. Only the necessary amount of photoresist is applied. For example, this technology cuts the amount of photoresist used on 5-generation glass substrates, which measure 1,100mm 1,250mm, by more than 60%, and cleaning and rinsing solution use is down by 90%, with extremely low power consumption.

*Spinless®: Registered trademark in Japan, No. 4,731,631

The TR130000 S Spinless® coating machine for 8-generation glass substrates

The TR130000 S Spinless® coating machine for 8-generation glass substrates

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