Characterizing Thin Films Using X-Ray Reflectometry

Table of Content

Introduction
STOE Thin Film Attachment
Experimental Procedure and Results

Introduction

The interference and reflection characteristics of thin films are affected by their properties. Ellipsometry and reflectometry are the most commonly used methods for measurement of these characteristics.

STOE Thin Film Attachment

Using the total scattering technique, the STOE thin film attachment determines the amount of X-ray radiation reflected from a thin film. With the STOE thin film attachment, the thickness of layers can be analyzed on the nanometer scale. For instance, it is possible to analyze single- and multilayer semiconductor process films.

STOE’s evaluation program, Layer, allows specifying up to six layers in a stack of films on a substrate and a buffer. Different types of substrate materials and films can be handled, including dielectric, metallic, crystalline or amorphous semiconductors. In reflectometry analyses, the result quality is strongly influenced by the misalignment of the sample. In order to ensure accurate alignment, STOE has specially designed a reflectometry sample holder.

Experimental Procedure and Results

A STOE Stadi MP diffractometer (Figure 1) featuring a scintillation counter as point detector has been used for data collection using Cu Kα1 radiation. A quasi-parallel beam is directed at the sample space using the focusing position. The adjustment blade suppresses undesirable parts of the beam by acting as a slit.

Figure 1. The STOE Stadi MP diffractometer

A silicon wafer coated with tantalum and polycrystalline silicon has been used as the sample. The program Layer, a component of the WinXPOW software suite, has been used to analyze the resulting data. Figure 2 and Table 1 present the study results.

Figure 2. Reflectometry measurement results

Table 1. Study results

polySi – Ta – Si(111): Measurement on Stadi MP
Last gof: 0.0288 after 53 cycles
Layer 1 (ploy Si)
Chemical composition: Si
Layer thickness: 1076.00 Å
Layer density: 2.330 g/cm3
Buffer-layer (Tantal)
Chemical composition: Ta
Layer thickness: 162.00 Å
Layer density: 16.650 g/cm3
Substrate (Si(111))
Chemical composition: Si
Layer density: 2.330 g/cm3

This information has been sourced, reviewed and adapted from materials provided by STOE.

For more information on this source, please visit STOE.

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