Paper
29 August 2005 Sub-0.1 μm optical track width measurement
Author Affiliations +
Abstract
In this paper, we will describe a technique that combines a common path scanning optical interferometer with artificial neural networks (ANN), to perform track width measurements that are significantly beyond the capability of conventional optical systems. Artificial neural networks have been used for many different applications. In the present case, ANNs are trained using profiles of known samples obtained from the scanning interferometer. They are then applied to tracks that have not previously been exposed to the networks. This paper will discuss the impacts of various ANN configurations, and the processing of the input signal on the training of the network. The profiles of the samples, which are used as the inputs to the ANNs, are obtained with a common path scanning optical interferometer. It provides extremely repeatable measurements, with very high signal to noise ratio, both are essential for the working of the ANNs. The characteristics of the system will be described. A number of samples with line widths ranging from 60nm-3μm have been measured to test the system. The system can measure line widths down to 60nm with a standard deviation of 3nm using optical wavelength of 633nm and a system numerical aperture of 0.3. These results will be presented in detail along with a discussion of the potential of this technique.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Richard J. Smith, Chung W. See, Mike G. Somekh, and Andrew Yacoot "Sub-0.1 μm optical track width measurement", Proc. SPIE 5858, Nano- and Micro-Metrology, 58580M (29 August 2005); https://doi.org/10.1117/12.611999
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KEYWORDS
Artificial neural networks

Interferometers

Optical tracking

Objectives

Fourier transforms

Signal to noise ratio

Optical testing

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