  We study surface and bulk properties of porous films produced by a model in
which particles incide perpendicularly to a substrate, interact with deposited
neighbors in its trajectory, and aggregate laterally with probability of order
$a$ at each position. The model generalizes ballistic-like models by allowing
attachment to particles below the outer surface. For small values of $a$, a
crossover from uncorrelated deposition (UD) to correlated growth is observed.
Simulations are performed in 1+1 and 2+1 dimensions. Extrapolation of effective
exponents and comparison of roughness distributions confirm Kardar-Parisi-Zhang
roughening of the outer surface for $a>0$. A scaling approach for small $a$
predicts crossover times as $a^{-2/3}$ and local height fluctuations as
$a^{-1/3}$ at the crossover, independently of substrate dimension. These
relations are different from all previously studied models with crossovers from
UD to correlated growth due to subsurface aggregation, which reduces scaling
exponents. The same approach predicts the porosity and average pore height
scaling as $a^{1/3}$ and $a^{-1/3}$, respectively, in good agreement with
simulation results in 1+1 and 2+1 dimensions. These results may be useful to
modeling samples with desired porosity and long pores.
