23 August 2000 Why single-machine processing overlay error still fails: reticle interference effect and our solution on IC foundry fab
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Abstract
Processing two consequent layers on the same exposure tool had long time been considered to be the terminated solution for overlay control by photolithography process engineers. Such measure would take advantage of excluding Lens distortion contribution to overlay performance and lead to only mask error, alignment accuracy, stage accuracy consume the overlay main budget. But in practice, large overlay error still could be observed even single machine run on scanner that could not be tolerable by current device requirement. How come. Reticle interference effect with alignment laser beam had been demonstrated to dominate such large overlay error contribution. Solutions to control and eliminate this effect on CI foundry fab were also presented. An advanced feedforward/feedback control system would compensate such error in advance. Also ARC coating on mask quartz side that would eliminate the interference effect will be mentioned and proved to be effective way for better overlay control performance.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
H. M. Sheng, Chen-Cheng Kuoe, L. G. Terng, Dong S. Cheng, Yung H. Liao, Joseph Guo, "Why single-machine processing overlay error still fails: reticle interference effect and our solution on IC foundry fab", Proc. SPIE 4182, Process Control and Diagnostics, (23 August 2000); doi: 10.1117/12.410069; https://doi.org/10.1117/12.410069
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