X-ray diagnostics of plasma deposited thin layers.
H. Wulff, Institute for Chemistry, Greifswald University, Germany
Abstract
The deposition of films by plasma techniques and the plasma treatment of solid surfaces are
well known and widely used methods. In order to understand the complexities involved in film
formation it is necessary to take a close look at the deposition region. This is usually the
substrate area that is subjected to plasma radiation and, in particular, to fluxes of energetic
and reactive charged and neutral particles in various excited states. Therefore, results of
detailed plasma diagnostics have to correlate with film properties.
Of particular interest is the analysis of film properties in the nanometer range. X-ray methods
can give a range of interesting information about how plasma deposition techniques
and plasma parameters influence deposited films and surface layers. Grazing incidence x-
ray diffractometry (GIXD) and x-ray reflectometry (XR) have been introduced as well
suited tools for investigations of plasma deposited thin layers. These x-ray methods
have a number of advantages compared to other commonly used techniques They are nondestructive techniques, therefore a sample can be reused an can be measured with
other techniques such as x-ray photoelectron spectroscopy (XPS), or atomic force
microscopy (AFM). A usable combination of GIXD and XR requires that the film thickness
does not exceed the upper physical absorption limit for the reflectometry measurements.
If this condition is fulfilled a combination of GIXD and XR can give a range of interesting
information about chemical, physical and crystallographic properties of thin films.
Conclusions can be drawn how plasma deposition techniques and plasma
parameters influence the film growth.
In this chapter
- the basic principles of GIXD and XR were introduced,
- the efficiency of these x-ray methods will be discussed in comparison with other
surface analysis methods
- examples will presented in consideration to
phase analysis of thin films
The most frequently used and the most important problem in the film
analysis is to prove the existence of a desired phase after film deposition or to
find out which phase or phases were formed
the influence of plasma parameters of film properties
gas composition, gas pressure, plasma power, substrate voltage can
influence chemical as well as physical properties of plasma deposited films.
The effect of oxygen flows and negative substrate voltages on film formation
process of ITO layers deposited by a dc magnetron will be presented
defect structure analysis of deposited films
Additional energy flux to growing films due to ion energy caused by different
substrate potentials can influence film properties observed in x-ray data.
plasma chemical reactions in the surface layers
Chemical reactive plasmas can form new compounds in the surface range. By
means of a combination of XR and GIXD the whole kinetic process of the
aluminium oxidation in a microwave plasma can be investigated and will be
presented here.
the influence of cluster size on cluster melting point
Fundamental physical interest on clusters arises due to their reduced size.
Connections between cluster size and melting behaviour investigated by insitu GIXD were discussed.
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