Improved overlay measurement of CMP processed layers

Jeong-Ho Yeo; Jeong-Lim Nam; Seok-Hwan Oh; Joo-Tae Moon; Young-Bum Koh; Nigel P. Smith; Andrew M.C. Smout

doi:10.1117/12.240095

21 May 1996 Improved overlay measurement of CMP processed layers

Jeong-Ho Yeo, Jeong-Lim Nam, Seok-Hwan Oh, Joo-Tae Moon, Young-Bum Koh, Nigel P. Smith, Andrew M.C. Smout

Proceedings Volume 2725, Metrology, Inspection, and Process Control for Microlithography X; (1996) https://doi.org/10.1117/12.240095
Event: SPIE's 1996 International Symposium on Microlithography, 1996, Santa Clara, CA, United States

Abstract

We report the results of an investigation into the quality of overlay data obtained from a chemical-mechanical polish (CMP) process. The limiting step height for standard bright field optical imaging is examined and found to be less than 200 angstrom. Tool repeatability improvements are demonstrated using a mixture of imaging system modifications and image processing techniques. Using these it is possible to achieve very repeatable data. Good tool precision is insufficient evidence of good data quality as the process can distort the target so that it does not accurately measure the stepper overlay error. We report an examination of data quality obtained using different target designs and both with and without an additional etch- back step to enhance the contrast of the image being measured. Several different techniques have been applied to determine whether the data is accurate. We conclude that bar and frame type targets give much more accurate results than traditional box styles. In addition the tool performance is also improved by using the same target designs. With this choice of target design accurate data is obtained and meaningful correction of stepper errors becomes possible.

Citation Download Citation

Jeong-Ho Yeo, Jeong-Lim Nam, Seok-Hwan Oh, Joo-Tae Moon, Young-Bum Koh, Nigel P. Smith, and Andrew M.C. Smout "Improved overlay measurement of CMP processed layers", Proc. SPIE 2725, Metrology, Inspection, and Process Control for Microlithography X, (21 May 1996); https://doi.org/10.1117/12.240095

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