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Marker studies of the solid state formation of CrSi2 on Pd2Si
Author(s)
Mars, Johan André
Date Issued
1998
Type
Thesis
Publisher
Peninsula Technikon
Abstract
The chemical system, Si < >1 Pd 1Cr, was investigated to study the formation of
CrSil on polycrystalline PdlSi, formed on Si<IOO> and epitaxial PdlSi formed on
Si<lll>. To ascertain the reaction mechanism during the formation, tantalum was used as
an inert marker, since it does not participate in the reaction and is readily measured by
Rutherford Backscattering Spectrometry (RBS). This investigation was performed in two
parts. In the first part, the tantalum was inserted in the PdlSi layer to determine which species;
palladium or silicon diffuses during CrSil formation. In the second part, the marker
was inserted in the CrSiI layer to determine whether chromium or silicon moves. In addition,
the effect of marker thickness on the growth of CrSiI was investigated.
The samples were prepared by electron gun evaporation in vacuum, the elements
being deposited on the particular silicon substrates. This was followed by the thermal
treatment of the samples at temperatures of 400,425,450,475,500 and 550°C. Normal
and dynamic Rutherford backscattering spectrometry was used to characterize the thin film
structures.
If the marker, when inserted in the PdISi layer, should move towards the
PdISi I CrSil interface then, the formation of CrSil would be due to the dissociation of
Pd2Si. In this case PdlSi dissociates into Pd and Si and the Si diffuses to the interface of
CrSi2 and Cr to form CrSil, whereas the Pd diffuses to the Si < > I Pd2Si interface to regrow
PdISi. However, if the marker position remains constant with respect to the Pd2Si
layer it can be concluded that the formation of CrSiI is due to the movement of Si from the
substrate to the interface of CrSi2 and Cr to form CrSiI. If the marker when inserted in the
CrSi2 should move towards the sample surface then the chromium diffuses to the interface
ofCrSi1 and PdlSi to react with the silicon, forming CrSi2 .
CrSil on polycrystalline PdlSi, formed on Si<IOO> and epitaxial PdlSi formed on
Si<lll>. To ascertain the reaction mechanism during the formation, tantalum was used as
an inert marker, since it does not participate in the reaction and is readily measured by
Rutherford Backscattering Spectrometry (RBS). This investigation was performed in two
parts. In the first part, the tantalum was inserted in the PdlSi layer to determine which species;
palladium or silicon diffuses during CrSil formation. In the second part, the marker
was inserted in the CrSiI layer to determine whether chromium or silicon moves. In addition,
the effect of marker thickness on the growth of CrSiI was investigated.
The samples were prepared by electron gun evaporation in vacuum, the elements
being deposited on the particular silicon substrates. This was followed by the thermal
treatment of the samples at temperatures of 400,425,450,475,500 and 550°C. Normal
and dynamic Rutherford backscattering spectrometry was used to characterize the thin film
structures.
If the marker, when inserted in the PdISi layer, should move towards the
PdISi I CrSil interface then, the formation of CrSil would be due to the dissociation of
Pd2Si. In this case PdlSi dissociates into Pd and Si and the Si diffuses to the interface of
CrSi2 and Cr to form CrSil, whereas the Pd diffuses to the Si < > I Pd2Si interface to regrow
PdISi. However, if the marker position remains constant with respect to the Pd2Si
layer it can be concluded that the formation of CrSiI is due to the movement of Si from the
substrate to the interface of CrSi2 and Cr to form CrSiI. If the marker when inserted in the
CrSi2 should move towards the sample surface then the chromium diffuses to the interface
ofCrSi1 and PdlSi to react with the silicon, forming CrSi2 .
Additional information
Thesis (MTech (Science))--Peninsula Technikon, Cape Town, 1998
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