  For infinite (bulk) quantum fluids of particles interacting via pairwise
sufficiently smooth interactions, the Wigner-Kirkwood formalism provides a
semiclassical expansion of the Boltzmann density in configuration space in even
powers of the thermal de Broglie wavelength $\lambda$. This result permits one
to generate an analogous $\lambda$-expansion for the bulk free energy and
many-body densities. The present paper brings a technically nontrivial
generalization of the Wigner-Kirkwood technique to semi-infinite quantum
fluids, constrained by a plane hard wall impenetrable to particles. In contrast
to the bulk case, the resulting Boltzmann density involves also
position-dependent terms of type $\exp(-2x^2/\lambda^2)$ ($x$ denotes the
distance from the wall boundary) which are non-analytic in $\lambda$. Under
some condition, the analyticity in $\lambda$ is restored by integrating the
Boltzmann density over configuration space; however, in contrast to the bulk
free energy, the semiclassical expansion of the surface part of the free energy
(surface tension) contains odd powers of $\lambda$, too. Explicit expressions
for the leading quantum corrections in the presence of the boundary are given
for the one-body and two-body densities. As model systems for explicit
calculations, we use Coulomb fluids, in particular the one-component plasma
defined in the $\nu$-dimensional (integer $\nu\ge 2$) space.
