  We study a non-Anderson disorder driven quantum phase transition in a
semi-infinite Dirac semimetal with a flat boundary. The conformally invariant
boundary conditions, which include those that are time-reversal invariant, lead
to nodal-like surface states on the boundary. In this case the boundary becomes
metallic at a critical disorder that is weaker than that for the
semimetal-diffusive metal transition in the bulk. The latter transition takes
place in the presence of a metallic surface; in the language of surface
critical phenomena this corresponds to the so-called extraordinary transition.
The lines of the surface and the extraordinary transitions meet at the special
transition point. To elucidate universal properties at different transitions on
the phase diagram, we employ renormalization group methods and compute the
corresponding surface critical exponents using $\varepsilon$-expansion.
