Research on the radiation hardened SOI devices with single-step Si ion implantation

Silicon-on-insulator（SOI） devices are sensitive to the total ionizing dose effect due to the existence of buried oxide.In this paper,an extra single-step Si ion implantation into buried oxide layer prior to the normal complementary metal–oxide–semiconductor transistor（CMOS） process is used to harden the SOI wafer.The top-Si quality of the hardened SOI wafer is confirmed to be good enough for device manufacturing through various characterization methods.The radiation experiments show that the total ionizing dose tolerance of the Si implanted SOI device is improved significantly.The metastable electron traps introduced by Si implantation is also investigated by electrical stress.The results show that these traps are very instable,and electrons will tunnel into or out of the metastable electron traps quickly after hot-electroninjection or hot-hole-injection.

Effect of copper ion implantation on corrosion morphology and corrosion behavior of LaFe_(11.6)Si_(1.4) alloy

The morphology analysis and electrochemical method were used to study the corrosion behavior of LaFe11.6Si1.4 alloy of copper ion implantation. X-ray photoelectron spectroscopy （XPS） and atomic emission spectroscopy （AES） research results showed that a 15 nm-thick oxide film was formed on the surface of sample, and the copper content reached the highest value at 60 nm with a normal distribution. Immersion experiments indicated that the corrosion happened in the copper-poor zone firstly and a galvanic connection was formed among different zones on the surface due to the inhomogeneous distribution of copper. Electrochemical experiment results showed that the corrosion was serious when the ion acceleration voltage increased, and the high acceleration could reduce the thermodynamic performance of corrosion of LaFe11.6Si1.4 alloy.

Planar nucleation and crystallization in the annealing process of ion implanted silicon

According to thermodynamic and kinetic theory,considering the variation of bulk free energy and superficial energy after nucleation as well as the migration of atoms,we study systematically the planar nucleation and crystallization that relate to two possible transition mechanisms in the annealing process of ion implanted S i：（1） liquid/solid transition：the critical nucleation work is equal to half the increased superficial energy and inversely proportional to the supercoolingΔT.Compared with bulk nucleation,the radius of the critical nucleus decreases by half,and the nucleation rate attains its maximum at T = Tm/2.（2） amorphous/crystalline transition：the atoms contained in the critical nucleus and situated on its surface,as well as critical nucleation work,are all directly proportional to the height of the nucleus,and the nucleation barrier is equal to half the superficial energy too.In addition,we take SiGe semiconductor as a specific example for calculation;a value of 0.03 eV/atom is obtained for the elastic strain energy,and a more reasonable result can be gotten after taking into account its effect on transition Finally,we reach the following conclusion as a result of the calculation：for the annealing of ion implanted Si,no matter what the transition method is—liquid or solid planar nucleation—the recrystallization process is actually carried out layer by layer on the crystal substrate,and the probability of forming a＂rod-like＂nucleus is much larger than that of a＂plate-like＂nucleus.