In this work the capability of pulsed ruby laser and multiscan electron beam techniques in the formation of Al-Si ohmic contacts on shallow (0.3 μm) junctions has been investigated. To measure the contact resistivity, properly designed test patterns have been employed, whereas to evaluate the junction leakage induced by the Al-Si interaction during sintering, the diode reverse current has been tested.
Laser beam annealing gives rise to scattered values of contact resistivity, ranging from 10-4 to 5 × 10-3 ohm-cm2 without any clear dependence on the energy used. The corresponding diode reverse currents were higher than those of the unannealed specimens by about three orders of magnitude.
E-beam annealing achieves contact resistivities on the order of 10-5 ohm-cm2 typical of conventional thermal treatment, with a parallel increase in the reverse current by only one order of magnitude.
These results indicate electron-beam annealing as a promising technique in the realization of Al-Si ohmic contacts for VLSI technology.