Papers by Keyword: Semiconductor Fabrication

Abstract: A hydrostatic bearing using ionic liquid (IL) has been developed to float semiconductor wafers in a high vacuum chamber. In semiconductor manufacturing, it is important to suppress overheating of wafers and maintain a constant temperature distribution. This method aims to achieve uniform temperature distribution by supplying IL from the backside of the wafer to float it, thereby without mechanical contact. However, since there are no examples of wafers levitated by hydrostatic bearings using IL in a high-vacuum environment, the effect of circulating IL to the vacuum conditions such as vacuum pressure and outgassing were investigated in this study. Experimental results showed that the developed prototype machine was capable of maintaining a stable ultrahigh-vacuum of 10^-5 Pa and supplying sufficient pressure to levitate wafers even when 100 ml of IL was circulated.

Abstract: In semiconductor fabrications, batch processing devices (BPD) are mainly used for oxidation, diffusion, deposition and performance test operations. To optimize scheduling solutions of non-identical semiconductor BPDs where existing multi-products and different due dates, a heuristic scheduling method based on Particle swarm optimization (PSO) and weighted cost rate (WCR) is proposed for minimizing the objective of the earliness/tardiness(E/T) penalties. The two-level heuristic scheduling algorithm is developed. Experiment results indicate that the proposed algorithm is valid and practical. Compared with the previous heuristic scheduling algorithms, it is more efficient in improving the weighted earliness/tardiness performance.