  We theoretically study the current-induced spin torque in antiferromagnetic
tunnel junctions, composed of two semi-infinite antiferromagnetic layers
separated by a tunnel barrier, in both clean and disordered regimes. We find
that the torque enabling the electrical manipulation of the N\'eel
antiferromagnetic order parameter is out of plane $\sim {\bf n}\times{\bf p}$,
while the torque competing with the antiferromagnetic exchange is in-plane
$\sim {\bf n}\times({\bf p}\times{\bf n})$. Here, ${\bf { p}}$ and ${\bf { n}}$
are the N\'eel order parameter direction of the reference and free layers,
respectively. Their bias dependence shows similar behavior as in ferromagnetic
tunnel junctions, the in-plane torque being mostly linear in bias while the
out-of-plane torque is quadratic. Most importantly, we find that the spin
transfer torque in antiferromagnetic tunnel junctions is much more robust
against disorder than in antiferromagnetic metallic spin-valves due to the
tunneling nature of spin transport.
