Surface Protection During Plasma Hydrogenation for Acceptor Passivation in InP.

Various dielectric and metallic films were examined as H-permeable surface protection layers on InP during H sub 2 or D sub 2 plasma exposure for passivation of acceptors in the InP. Plasma deposited SiN sub x, SiO sub 2, and a-Si(H) films ranging in thickness from 85 to 225angstroms were used to protect p-InP during D sub 2 plasma exposure at 250C. Optimum protective layer thickness were determined by a trade-off between the effectiveness of the layer to prevent P loss from the wafer surface and the ability to diffuse atomic H or D at a rate greater than or equal to that in the underlying InP. SIMS and capacitance-voltage depth profiling were used to determine the extent of D in-diffusion and acceptor passivation respectively. Sputter deposited W and e-beam evaporated Ti films ~100angstroms thick were also evaluated.