Phosphorus activation in silicon: To deglaze or not to deglaze, that is the question

Extremely efficient phosphorus drive-in into a high resistivity (100) Si substrate is achieved by an advanced doping technology, providing precise control over the amount of electrically active impurity dopants that are introduced into the semiconductor. A phosphorus δ-layer on deglazed and not deglazed silicon surfaces is formed by means of polystyrene homopolymers terminated with a P containing moiety. The P atoms from the δ-layer are injected into the Si substrate by a standard high temperature annealing in a rapid thermal processing (RTP) machine, operating at 1200 °C for 5 s. Depth distribution of the P atoms upon the drive-in procedure is investigated by ToF-SIMS analysis, highlighting the effective capability to inject the dopant impurities into the semiconductor substrate. Room temperature Hall measurements in van der Pauw configuration are performed as a function of the processing conditions to investigate the activation rates (ηa) of injected P atoms. Remarkably, depending on the surface characteristic before the grafting of the phosphorus terminated polymers, significantly different ηa values are attained. More precisely ηa ∼80% are achieved in the case of not deglazed Si surfaces. Conversely ηa ∼100% are measured in the case of deglazed Si surfaces, providing a clear evidence of a full activation of the dopant impurities injected into the silicon substrate. These experimental results path the way to the development of a mild and efficient technology for the doping of semiconductors.