With a market share of up to 90%, Japan continues to develop EUV photoresist

Latest update time：2021-08-31 10:23

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In the field of photoresist, Japan is the world's leading manufacturer, especially in EUV photoresist, where their market share is as high as 90%, but they do not seem to be slowing down.

According to a recent report by Nikkei, Fujifilm Holdings and Sumitomo Chemical will begin supplying materials for next-generation chip manufacturing as early as 2021, which will help smartphones and other devices move toward smaller and more energy-efficient trends. The report further stated that Fujifilm is investing 4.5 billion yen (42.6 million U.S. dollars) to equip its production plant in Shizuoka Prefecture, southwest of Tokyo, and will start mass production as early as next year. The company said that using this product, there is less residue, resulting in fewer defective chips.

Meanwhile, Sumitomo Chemical will provide a full range of photoresist production capabilities from development to production for a plant in Osaka by fiscal 2022. Due to its strong market, the company has already reached a tentative agreement to supply products to large manufacturers.

Shin-Etsu Chemical set up a factory in Taiwan to serve TSMC?

The latest report from Nikkei News pointed out that Japan's Shin-Etsu Chemical Co., Ltd. will spend about 30 billion yen (US$285 million) to increase the production capacity of photoresist, an important material for semiconductor factories, by 20%, and will produce it in Taiwan for the first time to expand supply for the production of advanced chips.

Shin-Etsu Chemical will invest in new equipment in Japan and Taiwan to produce photoresist, the material used to form circuit patterns on silicon wafers.

Shin-Etsu Chemical, Japan's leading maker of photoresists, is increasing production capacity as competition in the semiconductor materials sector intensifies and demand for chips used in 5G devices, data centers and other applications grows.

Nikkei reported that Shin-Etsu Chemical's Yunlin plant in Taiwan will be the first to add new production capacity from around February 2021. At that time, Shin-Etsu Chemical will begin producing this photoresist suitable for advanced extreme ultraviolet (EUV) lithography technology in Taiwan. In the past, this material was only produced in Japan. Shin-Etsu Chemical hopes that this move will meet the rising demand of customers such as TSMC.

In Japan, new equipment at Shin-Etsu Chemical's plant in Naoetsu, Niigata Prefecture, is scheduled to start operation in February 2022. Production capacity in Taiwan will increase by 50%, and the Naoetsu plant will increase by 20%, while the number of employees will also be expanded.

Shin-Etsu Chemical will also increase production for customers in South Korea, mainland China and other markets.

Other major Japanese photoresist manufacturers, including JSR and Tokyo Ohka Kogyo, also produce EUV photoresists both in Japan and overseas, while Sumitomo Chemical and Fujifilm are preparing to enter this field.

Further reading: What is photoresist?

Photoresist is one of the key materials for fine pattern processing in microelectronics technology. It is a light-sensitive mixed liquid composed of three main components: photosensitive resin, sensitizer and solvent. The required fine pattern is transferred from the mask to the pattern transfer medium on the substrate to be processed through photochemical reaction, exposure, development, etching and other processes. Exposure is through the irradiation or radiation of exposure sources such as ultraviolet light, electron beam, excimer laser beam, X-ray, ion beam, etc., so that the solubility of the photoresist changes.

According to the application field, photoresists mainly include four categories: printed circuit board (PCB) photoresist special chemicals (photoinitiators and resins), liquid crystal display (LCD) photoresist photoinitiators, semiconductor photoresist photoinitiators and other purpose photoresists. This article mainly discusses semiconductor photoresists.

Photoresist has been a core semiconductor material since it was invented in 1959. It was subsequently improved and applied to the manufacture of PCB boards, and in the 1990s, it was applied to the processing and manufacturing of flat panel displays. The final application areas include consumer electronics, home appliances, automotive communications, etc.

The photolithography process accounts for about 35% of the total chip manufacturing cost and takes 40% to 60% of the entire chip process, making it the most core process in semiconductor manufacturing.

Taking semiconductor photoresist as an example, in the photolithography process, the photoresist is evenly coated on the substrate. After processes such as exposure (changing the solubility of the photoresist), development (using the developer to dissolve the soluble part of the modified photoresist) and etching, the pattern on the mask is transferred to the substrate, forming a geometric figure that completely corresponds to the mask.

Photolithography technology continues to develop with the improvement of IC integration. In order to meet the higher requirements of integrated circuits for density and integration, semiconductor photoresists have continuously shortened the exposure wavelength to improve the ultimate resolution. The world's chip technology level has now entered the micro-nano level. The wavelength of photoresists has gradually increased from ultraviolet broad spectrum to g-line (436nm), i-line (365nm), KrF (248nm), ArF (193nm), F2 (157nm), and the most advanced EUV (<13.5nm) line level.

At present, the main photoresists used in the semiconductor market include g-line, i-line, KrF, and ArF. Among them, g-line and i-line photoresists are the most widely used in the market. The core technologies of KrF and ArF photoresists are basically monopolized by Japanese and American companies.

Photoresist not only has the characteristics of high purity requirements and complex processes, but also requires the corresponding lithography machine to be paired and debugged. Generally, a chip needs to undergo 10 to 50 lithography processes during the manufacturing process. Due to different substrates, different resolution requirements, different etching methods, etc., different lithography processes have different specific requirements for photoresists. Even for similar lithography processes, different manufacturers will have different requirements.

There are many types of photoresists for different application requirements, and these differences are mainly achieved by adjusting the photoresist formula. Therefore, adjusting the photoresist formula to meet differentiated application requirements is the core technology of photoresist manufacturers.

In addition, since the photolithography processing resolution is directly related to the chip feature size, and the performance of the photoresist is related to the size of the photolithography resolution, the interference and diffraction effects of light limit the photolithography resolution. The photolithography resolution is related to the exposure wavelength, numerical aperture and process coefficient.

The exposure wavelength of photoresist has moved from broad spectrum ultraviolet to g-line → i-line → KrF → ArF → EUV (13.5nm). As the exposure wavelength shortens, the ultimate resolution that photoresist can achieve continues to increase, the circuit pattern obtained by photolithography has better precision, and the corresponding photoresist price is also higher.

The design of the photolithography optical path is conducive to further improving the numerical aperture. With the development of technology, the numerical aperture has developed from 0.35 to greater than 1. The development of related technologies has also made the performance requirements of photoresists and their supporting products more stringent.

The process factor changes from 0.8 to 0.4, and its value is related to the product quality of the photoresist. Combined with technologies such as double mask and double etching, the existing photolithography technology enables us to complete 10nm process photolithography with 193nm laser.

In order to achieve 7nm and 5nm processes, traditional lithography technology has encountered bottlenecks, and EUV (13.5nm) lithography technology is about to emerge. TSMC and Samsung are also making arrangements in related fields. The EUV lithography optical path is based on reflection design, which is different from the refraction of the previous generation. The photoresist required is mainly inorganic photoresist, such as metal oxide photoresist.

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