Here, gold tin solder layers are analyzed by GD-OES
[16] (glow discharge optical emission spectroscopy). This
method ablades the metallization by glow discharge and
the optical emission is measured by spectroscopy. Hence,
even measurement of composition profiles is possible.
The relative measurement accuracy is 1% for the gold
concentration and 10% for the depth information if
appropriate calibration standards are used. A typical
profile measured on cosputtered gold tin alloy is shown in
Fig 3. It shows a gold rich surface and a very
homogeneous composition profile in the bulk. The gold
rich surface could be caused by the fact that the shutter of
the gold target is closed after the one of the tin target. But
a gold rich surface is in contrast to the literature [17]
where the segregation of tin to the surface is described.