The Influence of Tungsten Contact Filling on Junction Quality and Contact Resistance

In this paper the benificial effect of tungsten contact filling is described for two aspects of modern VLSI technology. First, aluminium spiking through thin TiW barrier layers is effectively prevented by W-plugs. This results in lower diode leakage currents, both for N
⁺
an d P
⁺
junctions. Second, the contact resistance to N
⁺
and P
⁺
junctions is lower when W contact filling is used. This effect becomes more pronounced as the diameter of the contacts decreases. It is concluded that W contact filling is needed to guarantee low leakage currents and low contact resistances.