Technology overview: Sapphire is a crystal created by melting aluminum oxide at temperature higher than 2,100˚C followed by being grown as a single crystal. Up until now, industrial use of sapphire was limited to LED field; however, application fields have been expanded and diversified due to improvement in manufacture technique and cost reduction by entrance of new manufacturers. Among various methods of growing sapphire, Kyropoulos method has an advantage of producing high-quality crystal, better for large caliber; however, process of seeding that induces initial crystallization by contacting seed crystals to surface of melted material must be performed. This process has to be conducted following an instruction manual strictly by a highly skilled engineer who has obtained work technique for a long period of time, which may be considered as a disadvantage. Since it is highly dependent on engineer and manual, the yield has not been stable, thereby posing difficulty in increasing production capacity. The problem triggered the development of key components for auto-seeding.

Core technologies of auto-seeding, which are the measurement of temperature and surface image of melted material, driving module automation and development of linking program, were developed and applied to growth furnace of sapphire. Through application of auto- seeding technology to existing process, sapphire production has been standardized, thereby contributing to stabilization of production yield rate. Therefore, the production is expected to grow more than 200% compared to the previous production when a Kyropoulos grower equipped with the developed technology is installed in mass-production line.

Industrialization: The iPhone by Apple, the smartphone manufacturer, uses sapphire for marketing of premium-quality phone, and major cell phone companies of China have also introduced products with application of sapphire front glass, targeting the large market of China. Furthermore, based on rapidly growing distribution rate of smartphones, China has aggressively engaged in investment for production facility of sapphire single crystal. Kyropoulos equipment applied with auto-seeding technology developed by DKAZTEC Co., Ltd. was acknowledged with its stable yield, large quantity productivity and low production cost, accomplishing sales in scale of KRW 14 billion to a Chinese company. In addition, large sapphire with excellence in optical quality was manufactured, and sapphire window used for defense was produced, which successfully internalized the material highly dependent on foreign countries. Through establishment of the foundation for the domestic field of sapphire and development of the technology, global competitiveness and leadership were secured.

Problem-solving in industrialization: Since the manual seeding previously used implemented the best decisions through multilateral interpretation on the situation based on various information, it posed a problem that was highly dependent on skills and experiences of engineers. In order to automate the process, the development was proceeded separately for a vision system that acts as human eyes, algorithm acting as brain, and driving module part acting as human arms. Errors created from the process of development were interpreted in a simple sense. For example, contamination created from evaporation of melted material and deformation of internal material by high temperature causes a problem of interfering with the vision system; however, the problem was solved with the development of the multichannel system. In addition, for performance of components in driving module (e.g. precision of pulling transfer distance, repeatability, weight accuracy, etc.) and reproducibility of initial form of the grown crystal, reliabilities of materials were obtained through the authorized testing institutes (utilized as statistical figures). As a result, reproducibility could be obtained by characteristics of highly repetitive motion, and the process stabilization was achieved based on the result. In particular, growth furnace of high-quality sapphire was applied with auto-seeding system, thereby preparing a foundation for improvement of the sapphire industry to higher level.

Technology developer: DKAZTEC Co., Ltd. / +82-61-460-5800 / www.dkaztec.co.kr

Kyropoulos growth equipment applied with the developed key components of auto-seeding

/  Analysis image (Captured) of auto-seeding

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