CNR ExploRA

Articolo in rivista, 2023, ENG, 10.1016/j.mssp.2023.107691

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

Gianluca Barin a b, Gabriele Seguini a, Riccardo Chiarcos c, Viviana Maria Ospina c, Michele Laus c, Cristina Lenardi b, Michele Perego a

CNR-IMM, Unit of Agrate Brianza, Via C. Olivetti 2, I-20864, Agrate Brianza, Italy b Università degli Studi di Milano, Via Celoria 16, I-20133, Milano, Italy c Università del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, I-15121, Alessandria, Italy

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 ?-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 ?-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 (?a) of injected P atoms. Remarkably, depending on the surface characteristic before the grafting of the phosphorus terminated polymers, significantly different ?a values are attained. More precisely ?a ~80% are achieved in the case of not deglazed Si surfaces. Conversely ?a ~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.

Materials science in semiconductor processing