  Low-angle cross sections are produced inside an Auger microprobe using the
equipped depth profile ion sputter gun. Simply the sample is partly covered by
a mask. Utilizing the edge of this mask the sample is sputtered with ions. Due
to the shading of the mask a cross section is produced in the sample. The slope
of this cross section is considerably shallower than given by the geometrical
setup. This is attributed to self-alignment effects, which are due to missing
sputter cascades in the transition area between sputtered and shaded sample
regions and a chamfering of the mask edge. These self-alignment effects are
studied here using a 104.6 nm thick SiO2 layer thermally grown on a Si
substrate. In this study on one hand for a fixed ion impact angle of 15.8{\deg}
as function of the sputter time several in-situ low-angle cross sections were
produced. This way slope angles between an ultimate low slope angle of
0.014{\deg} and 0.085{\deg} were achieved. On the other hand for a fixed
sputter time the ion impact angle was varied between 14.8{\deg}and 70.8{\deg}.
For these samples cross section slope angles between 0.031{\deg}and
0.32{\deg}are observed. These results demonstrate the distinct slope flatting
of in-situ cross sectioning.
