Low Thermal Budget Activation of B in Si

Abstract

Advanced devices may today require implantation and annealing steps after the metallic interconnection realization. Depending on the application, a thin p-doped layer has to be formed after wafer bonding. The issue, in such a case, is to correctly anneal the Boron implanted layer without degrading the buried devices and interconnections which lies at a depth around 3pim below the surface. Here, we propose to study different way to anneal this thin p-doped layer. Low energy and low dose implantations are performed without reaching the amorphisation threshold. Long thermal annealing at 400°C (RTP) and UV laser annealing are investigated through sheet resistance, thermal wave, SIMS or TEM. On one hand, a significant activation is obtained with RTP at temperature as low as 400°C and that Boron is activated with a better activation rate with B+ than with BF2+. On the other hand, we achieve a much better activation with laser annealing as compared to RTP regardless of the implantation conditions.

Investigation of Excimer Laser Annealing of Si using Photoluminescence at Room Temperature

“…Besides the formation of shallow junctions, laser annealing can be used for applications such as recristallization of poly or amorphous silicon [3]- [4] or all applications where heat has to be confined at the surface to preserve the integrity of any buried devices [5]. For the confinement of the heat near the silicon surface, the most appropriate tool is the excimer laser (X=308nm) where most of the radiation is absorbed in less than 100nm in depth.…”