Anodic Behavior - Electrochemistry of Silicon and Its Oxide - page 211

found to follow the rate of change in thickness of the oxide film and it reaches a
maximum when the rate of change in thickness is the largest. 855,862,950 Figure 5.56 shows
that the rate of thickness change of the oxide film has a maximum coinciding with the
generation current peak and a minimum coinciding with the maximum of the dissolu-
tion rate during a period of current. 950 The amplitude of oxide thickness oscillation
depends on solution composition and potential. 948,950 Figure 5.57 shows the minimum
and maximum oxide thicknesses as a function of potential; both increase with increas-
ing potential but the maximum thickness increases more than the minimum thickness.
Other properties of the anodic oxide also oscillate. It is found that the current
peak, corresponding to the maximum oxide growth rate, is accompanied by a decrease
in the density of the oxide film indicating the oxide film at the current peak is of
lower quality than that at the current valley. 408,950 The variation of the density of the
oxide formed at different times during a period of oscillation in turn results in the
variation of the etching rate of the oxide as shown in Fig. 5.56. 950 Such a change of
oxide property is also shown in the etch rate variation in the direction normal to
the oxide film as shown in Fig. 4.27. Compressive stress is found to develop in the
oxide during oscillation with the maximum stress associated with the potential maxi-
mum. 122 The effective dissolution valence, about 4, is also found to oscillate along