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Proceedings Paper

OCD study of critical dimension and line-shape control of shallow-trench-isolation structures
Author(s): Ye Feng; Xiaodong Zhang; Beverly Cheung; Zhuan Liu; Mita Isao; Manabu Hayashi
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Paper Abstract

Shallow-Trench-Isolation (STI), as one of the primary techniques for device isolation in complementary metal-oxide semiconductor (CMOS), requires accurate and precise CD and line-shape control during wafer process. Thus, the measurement of the critical dimensions after lithography and after formation of the STI structure is extremely important for process control. Currently used SEM technologies are either destructive or incapable of identifying the profile features. The necessary averaging of CD-SEM measurements to compensate for its large error diminishes its usage in automatic process control. In this paper we use the Optical Critical Dimension (OCD) technique to study focus exposure matrix (FEM) wafers of photoresist patterns and STI structures and compare the results with CD-SEM measurements. OCD measurement is performed with normal-incidence polarized reflectometry. Rigorous Coupled-Wave Analysis (RCWA) is combined with real-time regression to provide CD and profile parameters with excellent sensitivity to sub-50 nm grating lines. Thus, non-destructive and fast real-time measurements are easily accomplished during wafer processing. Optimization of STI model parameters is discussed. The critical dimensions of 121 dies extracted by OCD exhibit excellent correlation with those obtained by CD-SEM, with R-squared as high as 0.995 on STI wafers.

Paper Details

Date Published: 24 May 2004
PDF: 10 pages
Proc. SPIE 5375, Metrology, Inspection, and Process Control for Microlithography XVIII, (24 May 2004); doi: 10.1117/12.536582
Show Author Affiliations
Ye Feng, Nanometrics, Inc. (United States)
Xiaodong Zhang, Nanometrics, Inc. (United States)
Beverly Cheung, Nanometrics, Inc. (United States)
Zhuan Liu, Nanometrics, Inc. (United States)
Mita Isao, Semiconductor Leading Edge Technologies, Inc. (Japan)
Manabu Hayashi, Semiconductor Leading Edge Technologies, Inc. (Japan)

Published in SPIE Proceedings Vol. 5375:
Metrology, Inspection, and Process Control for Microlithography XVIII
Richard M. Silver, Editor(s)

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