  Amorphous hydrogenated silicon nitride
($\textit{a}$-SiN$_\mathrm{\textit{x}}$:H) thin films irradiated with 100 MeV
Ni$^{7+}$ results in the formation of continuous ion track structures at the
lower fluence of $5\times{10^{12}}$ ions/cm$^2$ whereas at higher fluence of
$1\times{10^{14}}$ ions/cm$^2$ the track structures fragment into discontinuous
ion track like structures . The observation of the discontinuous ion track like
structures at the high fluence of $1\times{10^{14}}$ ions/cm$^2$ shows clearly
that higher fluence irradiation may not always lead to dissolution of the
microstructure formed at lower fluence. The results are understood on the basis
of a dynamic electronic energy loss (S$_{e}$) in the course of irradiation
resulting from the out-diffusion of hydrogen from the films and a continuous
increase in density of $\textit{a}$-SiN$_\mathrm{\textit{x}}$:H films.
