Characterization of residual implant damage by generation time technique

The quality of an implanted layer was characterized using non-contact generation lifetime. This technique does not require fabrication of any junction devices or MOS capacitors. The generation lifetime is measured by monitoring the surface voltage decay during collapsing of the deep depletion created by a pulse of corona charge placed on the wafer surface. The voltage decay, measured with the vibrating Kelvin probe, is due to the generation of minority carriers similar to the capacitance transient measurement of generation lifetime in MOS capacitors. Residual implant damage is manifested by faster generation rate and therefore faster voltage decay rate. Generation lifetime is measured versus implant energy and annealing temperature.The corona based generation lifetime technique yields additional useful parameter namely dopant concentration. The dopant concentration is calculated from the breakdown voltage and is determined by the implant distribution and depletion width at breakdown conditions.

► Generation lifetime is suitable to characterize the quality of silicon surface layer.
► Residual implant damage is quantified using generation time technique.
► Measurements are done using non-contact corona – Kelvin approach.
► Generation lifetime and doping concentration are obtained from a voltage decay.
► Measurement depth is less than 1 μm from the surface.