Nanosecond Laser Annealing for Phosphorous Activation in Ultra-Thin Implanted Silicon-On-Insulator Substrates

In this work it is shown that laser annealing can be used for electrical activation of phosphorus implanted in extremely thin SOI structures. We characterized crystallinity, surface morphology, dopant diffusion and activation as a function of the laser energy density. It is evidenced that pulsed laser annealing (wavelength: 308 nm and pulse duration: 160 ns) allows the perfect crystal recovery of the implanted silicon layers. An optimum was found for a fluence (0.85 J/cm
²
for the blanket SOI wafers used here) for which a perfect mono-crystalline SOI layer is obtained. Moreover, sheet resistance evolution shows that very high activation rates, comparable to those obtained by rapid thermal processing or solid phase epitaxial regrowth, can be achieved. The impact of multi-pulse (2 or 5 cumulated pulses) annealing as well as the use of shorter pulses (80 ns) is investigated.