  We describe the use of laser-enhanced etching of fused silica in order to
build multi-layer ion traps. This technique offers high precision of both
machining and alignment of adjacent wafers. As examples of designs taking
advantage of this possibility, we describe traps for realizing two key elements
of scaling trapped ion systems. The first is a trap for a cavity-QED interface
between single ions and photons, in which the fabrication allows shapes that
provide good electro-static shielding of the ion from charge build-up on the
mirror surfaces. The second incorporates two X-junctions allowing
two-dimensional shuttling of ions. Here we are able to investigate designs
which explore a trade-off between pseudo-potential barriers and confinement at
the junction center. In both cases we illustrate the design constraints arising
from the fabrication.
