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Method for using an extinction coefficient to determine film grain size

IP.com Disclosure Number: IPCOM000019837D
Publication Date: 2003-Oct-01
Document File: 2 page(s) / 111K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for using an extinction coefficient to determine film grain size. Benefits include improved performance.

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Method for using an extinction coefficient to determine film grain size

Disclosed is a method for using an extinction coefficient to determine film grain size. Benefits include improved performance.

Background

         Conventional metrology enables the extinction coefficient, k, to support variations in film properties. However, a correlation to grain size was not known. Additionally, conventional metrology does not monitor the value of k at critical wavelengths to maximize the sensitivity to the grain size.

General description

         The disclosed method uses an extinction coefficient to determine film grain size. The extinction coefficient, k, of a film in the ultraviolet (UV) portion of the spectrum is very sensitive to the grain size of the film. Using k to determine the grain size is much faster than using standard metrology techniques, such as x-ray diffraction. The disclosed method enables the monitoring of the grain size during standard optical thickness measurements performed for thickness process control.

Advantages

         The disclosed method provides advantages, including:

•         Improved performance due to the improved control of film grain size

Detailed description

         The optical index, n, and extinction, k, of a material are determined by the dipolar and resonant interaction of electromagnetism (EM) with the material. The critical points are caused by the resonant effect. The observed two critical points of Si can be correlated with the crystallinity of Si (see Figures 1 and 2).

         The n an...