The effect of 3D patterns on the heating of silicon substrates was investigated theoretically and experimentally. As energy sources RTA systems based on radiant heating (i.e. lamp-based) and on conduction heating (wafer placed in very close proximity to hot surfaces) were applied. The 3D patterns were trenches with dimensions 150-450nm wide, and 400nm deep. In case of lamp-based systems with heat-up rates of 75°C/s within-die temperature variations of 10-20°C were observed. In case of conduction-based systems with heat-up rates up to 900°C/s the impact of the 3D structures was negligible. Both types of systems were modeled, and a reasonable correlation with the experimental data was found.

Laser annealing can be used for applications that require confinement of heat on the top surface in order to preserve the integrity of buried structures. To confine heat near the silicon surface, the most appropriate tool is UV laser. Here, two excimer lasers with different characteristics were used to anneal boron in silicon. The first one has pulse duration of about 180ns and the second one of about 20ns in scanning mode. Regarding the crystal damage characterization, we report that room temperature photoluminescence (RT-PL) is a powerful and non-destructive technique to monitor crystal damage evolution. In order to investigate the effect of a surface oxide on laser annealing, samples with different (1, 20 and 150 nm-thick) surface oxide layers have been annealed. From RT-PL data, the crystal quality is found to improve with increasing laser power density. However the presence of the oxide layer leads to sudden degradation of the PL response for laser energy densities exceeding the melting threshold of Si.

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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.

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