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Proceedings Paper

Metrology of deep trench structures in DRAM using FTIR reflectance spectrum
Author(s): Chuanwei Zhang; Shiyuan Liu; Tielin Shi
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Paper Abstract

The demand for advanced DRAM technologies with smaller ground rules lead to new challenges for online metrology of high aspect-ratio deep trench structure. In addition to common metrology methods like ellipsometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM), the use of further measurement techniques are needed for advanced node technology. This paper proposes a technique for metrology of critical dimension (CD) of deep trenches formed as capacitors in advanced dynamic random access memory (DRAM) using Fourier-transform infrared (FTIR) reflectance spectrometry. This technique is based on a fast but accurate modeling of the complex periodic deep trench structure, which is represented as a multilayer thin film stack with a combination of homogeneous layers on the silicon substrate using effective medium approximation approach. The metrology problem is solved by an artificial neural network (ANN) and Levenberg-Marquardt (LM) combined algorithm to find the values of the modeling parameters which should produce a best fit to the given measured spectrum. This technique is validated by simulation of extracting geometry parameter of actual DRAM trench structures, and demonstrated to be an adequate approach for the determination of the structure parameters.

Paper Details

Date Published: 3 February 2009
PDF: 8 pages
Proc. SPIE 7160, 2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications, 716017 (3 February 2009); doi: 10.1117/12.808080
Show Author Affiliations
Chuanwei Zhang, Huazhong Univ. of Science and Technology (China)
Shiyuan Liu, Huazhong Univ. of Science and Technology (China)
Tielin Shi, Huazhong Univ. of Science and Technology (China)


Published in SPIE Proceedings Vol. 7160:
2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications

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