With semiconductor-device geometry shrinking and becoming more complex, conventional aqueous cleaning/drying of semiconductor surfaces tends to collapse high-aspect-ratio nano-structures due to the surface tension of rinsing water. This is one of the most significant problems in leading-edge semiconductor manufacturing. Some current problems in the most advanced semiconductor surface cleaning and several possible solutions to overcome the shortcomings of water-based cleaning will be described and discussed with special emphasis on non-aqueous or dry wafer-surface cleaning technologies to prevent the pattern collapse problem. While semiconductor device geometry will scale down to 5-nm and below in the near future, completely different materials and device structures will be introduced in the semiconductor-device manufacturing. Larger diameter (450-mm) silicon wafers will also be employed in the future. There will be more research challenges and opportunities in developing innovative semiconductor surface cleaning and conditioning technologies for these future applications.
Semiconductor cleaning is a very important process in integrated circuit manufacturing, and the removal of high dose ion implanted photoresist is a big challenge in semiconductor cleaning owing to their carbonized crust layer generated on and near the surface of the photoresist layer. Microbubbles are a promising candidate in single wafer spin cleaning process for the removal of the crust generated photoresist without any substrate loss. And the bubbles are gas bodies less than 50 micrometer in diameter and shrink underwater due to the rapid dissolution of the interior gas. It has been demonstrated that the bubbles can generate free radicals during the collapsing process under water through the dispersion of the elevated energy accumulated as the surface electricity during the collapsing process of microbubble. In this article the author introduces the fundamental properties of microbubble and their several examples relating to semiconductor cleaning.
Ultrapurewater is essentially used in wet processes of semiconductor manufacturing in order to rinse out impurities on wafers and to prepare chemical solutions for wafer cleaning. The quality requirement for the ultrapurewater is getting higher along with the advance of semiconductor devices. The quality load map with analytical control items, purification facilities and production system of the ultrapurewater are overviewed. The achievements in the technologies of reducing a trace amount of fine particles and metal impurities, which would particularly cause yield reductions by the wafer contaminations, are described. In addition, the recent works on hydrogen peroxide in the ultrapurewater is described as well.
Recently, large scale superconducting cavity systems are applied for large accelerators around the world, such as SuperKEKB, SNS, CEBAF and so on. And the huge accelerator of ILC of 40 km long linear collider is planed. The superconducting cavity has a simple structure which is surrounded by the superconducting material of niobium to store the high RF field with small heat loss. The preparation of inner surface of the cavity is the most important issue for the high field and the stable operation of superconducting cavity.
Vacuum vapor washing+vacuum drying process and vacuum ultrasonic washing process are major process in vacuum washing. Both process are usually adopted in hydrocarbon base washing machine. The latter is adopted in water base washing machine.