  We report on the realization of micropillars with site-controlled quantum
dots (SCQDs) in the active layer. The SCQDs are grown via the buried stressor
approach which allows for the positioned growth and device integration of a
controllable number of QDs with high optical quality. This concept is very
powerful as the number and the position of SCQDs in the cavity can be
simultaneously controlled by the design of the buried stressor. The fabricated
micropillars exhibit a high degree of position control for the QDs above the
buried stressor and $Q$-factors of up to 12000 at an emission wavelength around
930 nm. We experimentally analyze and numerically model the cavity $Q$-factor,
the mode volume, the Purcell factor and the photon-extraction efficiency as a
function of the aperture diameter of the buried stressor. Exploiting these SCQD
micropillars, we experimentally observe the Purcell enhancement in the
single-QD regime with $F_P$ = 4.3 $\pm$ 0.3.
