Paper PS-ThP23
Impact of Charge Separation Grid Design on Wafer Level Device Performance in an Advanced Plasma Asher

Thursday, October 22, 2015, 6:00 pm, Room Hall 3

Tradition plasma asher design depends on the grid, or baffle between source and wafer to separate ionized species from activated neutral so more activated neutral is preferred to reach wafer surface to react with photoresist. However, the more you separate the neutral species, the lower the ash rate in general due to loss mechanism during the separation process. In addition, the grid design also controls the ash rate uniformity and affects many other critical device parameters to the final device wafer performance. Therefore, it is extremely important to choose the correct design to the right process application. This paper discussed the impact of advanced plasma asher grid design on the device performance in process uniformity and device response. It is found that grid materials are critical to reduce the ionized species to reach the wafer surface with the conductive grounded grid to be the best for ionized species separation. In addition, the conductive grounded double grid design can not only have better particle and defect performance but also remove any possible UV impact on device from strong UV generated from high ash rate high power recipes. This has contributed to better yield in the production environment down to 10nm technology node.