Clean focus, dose and CD metrology for CD uniformity improvement

Honggoo Lee; Sangjun Han; Minhyung Hong; Seungyoung Kim; Jieun Lee; DongYoung Lee; Eungryong Oh; Ahlin Choi; Nakyoon Kim; John C. Robinson; Markus Mengel; Rovira Pablo; Sungchul Yoo; Raphael Getin; Dongsub Choi; Sanghuck Jeon

doi:10.1117/12.2299976

13 March 2018 Clean focus, dose and CD metrology for CD uniformity improvement

Honggoo Lee , Sangjun Han, Minhyung Hong, Seungyoung Kim, Jieun Lee, DongYoung Lee, Eungryong Oh, Ahlin Choi, Nakyoon Kim, John C. Robinson, Markus Mengel , Rovira Pablo , Sungchul Yoo, Raphael Getin, Dongsub Choi, Sanghuck Jeon

Author Affiliations +

Proceedings Volume 10585, Metrology, Inspection, and Process Control for Microlithography XXXII; 105852A (2018) https://doi.org/10.1117/12.2299976
Event: SPIE Advanced Lithography, 2018, San Jose, California, United States

Abstract

Lithography process control solutions require more exacting capabilities as the semiconductor industry goes forward to the 1x nm node DRAM device manufacturing. In order to continue scaling down the device feature sizes, critical dimension (CD) uniformity requires continuous improvement to meet the required CD error budget. In this study we investigate using optical measurement technology to improve over CD-SEM methods in focus, dose, and CD. One of the key challenges is measuring scanner focus of device patterns. There are focus measurement methods based on specially designed marks on scribe-line, however, one issue of this approach is that it will report focus of scribe line which is potentially different from that of the real device pattern. In addition, scribe-line marks require additional design and troubleshooting steps that add complexity. In this study, we investigated focus measurement directly on the device pattern. Dose control is typically based on using the linear correlation behavior between dose and CD. The noise of CD measurement, based on CD-SEM for example, will not only impact the accuracy, but also will make it difficult to monitor dose signature on product wafers. In this study we will report the direct dose metrology result using an optical metrology system which especially enhances the DUV spectral coverage to improve the signal to noise ratio. CD-SEM is often used to measure CD after the lithography step. This measurement approach has the advantage of easy recipe setup as well as the flexibility to measure critical feature dimensions, however, we observe that CD-SEM metrology has limitations. In this study, we demonstrate within-field CD uniformity improvement through the extraction of clean scanner slit and scan CD behavior by using optical metrology.

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Honggoo Lee , Sangjun Han, Minhyung Hong, Seungyoung Kim, Jieun Lee, DongYoung Lee, Eungryong Oh, Ahlin Choi, Nakyoon Kim, John C. Robinson, Markus Mengel , Rovira Pablo , Sungchul Yoo, Raphael Getin, Dongsub Choi, and Sanghuck Jeon "Clean focus, dose and CD metrology for CD uniformity improvement", Proc. SPIE 10585, Metrology, Inspection, and Process Control for Microlithography XXXII, 105852A (13 March 2018); https://doi.org/10.1117/12.2299976

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KEYWORDS

Semiconducting wafers

Metrology

Critical dimension metrology

Scanners

Modulation

Process control

Finite element methods

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