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Proceedings Paper

Influence of semiconductor manufacturing process variation on device parameter measurement for angular scatterometry
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Paper Abstract

The influence of semiconductor manufacturing process variation on device parameter measurements for angular scatterometry was studied. Process variations, e.g, temperature and pressure variation of poly deposition, are considered to affect the optical properties of the deposition layer, and hence cause inaccurate model-based scatterometry measurements. This study investigates measurement error of device parameters if the optical properties change but the model stays for the same in angular scatterometry. A series of diffracted signatures was generated whose optical properties change slightly but keep the same structure. This work measured n (refractive index) and k (extinction index) of materials on wafer from the nominal process condition. Then, n and k are used to create a comparison library. The comparison library fixes all parameters other than varying CD (critical dimension) parameter. When poly layer n changes, the scattering signatures also change. The inaccuracy of CD measurement could be evaluated by comparing varying signatures due to optical properties change to the nominal process condition. An optimal structure design and feature region selection algorithm was developed to reduce errors introduced by these process variations to CD measurement. For angular scatterometry, the reflectance at some scan angles performs lower sensitivity to the optical parameters variation than the reflectance at other scan angles. By determining which scan angles contain less sensitivity and further optimize target design within the process variation range, the influence of process variation on device parameter measurement and the number of measurements used in the inversion process can be reduced. By using 65nm and 45nm as design rules, optimized grating structure with most sensitivity to CD measurement and the least influence on poly refractive index variation were obtained. The optimized grating structures are suitable for inline semiconductor process control of CD measurement for scatterometry.

Paper Details

Date Published: 24 March 2006
PDF: 9 pages
Proc. SPIE 6152, Metrology, Inspection, and Process Control for Microlithography XX, 61521J (24 March 2006); doi: 10.1117/12.655995
Show Author Affiliations
Shih-Chun Wang, Industrial Technology Research Institute (Taiwan)
Yi-Sha Ku, Industrial Technology Research Institute (Taiwan)
Deh-Ming Shyu, Industrial Technology Research Institute (Taiwan)
Chun-Hung Ko, Industrial Technology Research Institute (Taiwan)
Nigel Smith, Accent Optical Technology (Taiwan)

Published in SPIE Proceedings Vol. 6152:
Metrology, Inspection, and Process Control for Microlithography XX
Chas N. Archie, Editor(s)

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