Buried spongy‐like layers in silicon implanted with He⁺, annealed and treated in D⁺ plasma

Abstract

Implantation of silicon with He+ ions (energy 300 keV, dose 5×1015 cm–2) and subsequent processing of Si:He structures at high temperature (HT) up to 1270 K under Ar hydrostatic pressure (HP) up to 1.2 GPa results in a creation of spongy‐like buried layer at the projected range of He ions, which is about 1.4 μm depth. Upon subsequent treatment of Si:He structures at 573 K in deuterium plasma under 3×102 Pa, deuterium is accumulated with concentrations up to about 1019 cm–3 at two different well pronounced local regions: (i) subsurface region with the width of about 0.5 μm and (ii) region‐around the projected range of He ions. As follows from TEM, X‐Ray and SIMS measurements, microstructure of nano‐structured spongy‐like layer and D concentration are dependent on HT, HP and processing time. It is established that further annealing of plasma treated Si:He,D at 723 K under 105 Pa/1.1 GPa for 1 h leads to a release of deuterium from both mentioned above local regions of the Si:He,D structures. It is concluded that spongy‐like buried layer created by He+ implantation can be used for gettering / accumulation of deuterium, which can be of interest for ion cut based technology. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

MicroRaman studies of implantation‐induced amorphization of Si and subsequent regrowth under high‐pressure and high‐temperature treatment

“…Note that we did not observe any Raman evidence for the formation of buried spongy‐like (porous) layers at post‐implantation HT–HP treatment similar to those reported in Refs. 6–10 for H + , He + , and N + ‐implanted Si. Evidently, in our case of self‐implanted silicon, the SPER imperfections related to the implantation‐induced alien atoms are not revealed.…”

“…The presence of impurities is known to produce different effect on the SPER kinetics: group‐III and group‐V dopants enhance SPER rate while impurities like H, N, C, and O retard the regrowth process (3 and references therein). Implantation or co‐implantation of silicon with hydrogen, helium, or nitrogen ions followed by appropriate high‐temperature and high‐pressure (HT–HP) treatment can lead to the formation of a buried spongy (porous‐like) layer in Si, its depth being of the order of the projected range of the implanted ions R p 6–10. The formation of pores in Si:H, Si:He, or Si:N is related to imperfect SPER of amorphous Si formed due to the implantation and to a creation of gas (e.g., H 2 )‐filled bubbles.…”

Deuterium accumulation within nano‐structured layers in Si:He upon plasma treatment

“…As it has been stated for self-implanted silicon (Si:Si), buried defect areas, produced by heavy implantation of Cz-Si with Si + , may getter / accumulate hydrogen [1]. Similar accumulation has been stated for Cz-Si implanted with hydrogen or He + (Si:He) and processed at high temperature (HT) under enhanced hydrostatic pressure (HP) [2].…”

“…2). The plasma treatment of Si:He processed at HT-HP results also in a strong deuterium accumulation at the near-R p region [2].…”