  We investigate numerically spherically symmetric collapse of a scalar field
in the semi-classical approximation. We first verify that our code reproduces
the critical phenomena (the Choptuik effect) in the classical limit and black
hole evaporation in the semi classical limit. We then investigate the effect of
evaporation on the critical behavior. The introduction of the Planck length by
the quantum theory suggests that the classical critical phenomena, which is
based on a self similar structure, will disappear. Our results show that when
quantum effects are not strong enough, critical behavior is observed. In the
intermediate regime, evaporation is equivalent to a decrease of the initial
amplitude. It doesn't change the echoing structure of near critical solutions.
In the regime where black hole masses are low and the quantum effects are
large, the semi classical approximation breaks down and has no physical
meaning.
