Silicon wafer oxygenation from SiO2 layers for radiation hard detectors

Radiation produces lattice damage in silicon by displacing the atoms from t heir original positions and thereby generating the corresponding defects. A s a result, new states are created in the semiconductorforbidden band gap, negatively affecting the electrical performance of the devices, Endurance t o radiation can be improved by having a high oxygen concentration in the si licon. For detector fabrication, high resistivity silicon is also needed, t hus float zone wafers are preferred; however, this kind of material exhibit s a low oxygen concentration. Although different ways to incorporate oxygen in float zone silicon have been proposed, all of them imply modifications during the ingot growth. Thermal diffusion from SiO2 layers on polished waf ers is an interesting alternative to improve their oxygen content. Differen t thermal processes aimed at obtaining oxygen enriched silicon for the fabr ication of radiation hard detectors have been tested. Attention has also be en paid to carbon introduction during processing since, high concentrations of this element has been proved deleterious. (C) 2000 Elsevier Science Ltd . All rights reserved.