Damage accumulation in Si during high-dose self-ion implantation

Abstract

Accumulation and annealing of damage in Si implanted with self-ions to high doses were investigated using a combination of grazing incidence diffuse x-ray scattering, high-resolution x-ray diffraction scans, and transmission electron microscopy. During implantation at 100°C, small vacancy and interstitial clusters formed at low doses, but their concentrations saturated after a dose of Ϸ3 ϫ 10 14 cm −2. The concentration of Frenkel defects at this stage of the implantation was Ϸ1 ϫ 10 −3. At doses above 1 ϫ 10 15 cm −2 , the concentration of implanted interstitial atoms began to exceed the Frenkel pair concentration, causing the interstitial clusters to grow, and by Ϸ3 ϫ 10 15 cm −2 , these clusters formed dislocation loops. Kinematical analysis of the rocking curves illustrated that at doses above 1 ϫ 10 15 cm −2 the "plus one" model was well obeyed, with one interstitial atom being added to the dislocation loops for every implanted Si atom. Measurements of Huang scattering during isochronal annealing showed that annealing was substantial below 700°C for the specimens irradiated to lower doses, but that little annealing occurred in the other samples owing to the large imbalance between interstitial and vacancy defects. Between 700 and 900°C a large increase in the size of the interstitial clusters was observed, particularly in the low-dose samples. Above 900°C, the interstitial clusters annealed.

On the microstructure of Si coimplanted with H+ and He+ ions at moderate energies

“…20 For medium and heavy ions implantation, such individual effects are clearer due to the reasonable spatial separation between vacancy, ion, and interstitial profiles. [20][21][22] In the case of light ions as H + and He + , the closer location of damage and ion profiles renders a more intricate system. The approach adopted here to get an insight on the physical origin of strain is to first identify its characteristic depth-distribution.…”

Nonlinear effects in defect production by atomic and molecular ion implantation

“…Saturation behavior of damage is characteristic of irradiated materials, where recombination reactions occur. 43 For silicon irradiated at room temperatures, the fluence required for saturation exceeds that required for amorphization; therefore, the as-implanted damage increases without saturation with increasing defect concentration. 19 However, for elevated temperature as in the present case, the saturation concentration is reduced.…”

Formation of Ultra-Shallow Junctions

“…Interstitial supersaturation results from the clustering of this one excess interstitial per implanted ion and not the entire distribution of implant-generated interstitials. This is popularly known as the þ1 model (Zhong et al, 2004).…”

“…Higher moment distributions such as Pearson-IV distribution (Zhong et al, 2004) are used to simulate experimental implanted profiles more accurately. These distributions and models tend to fail for heavier dopant ions and low energies, conditions that are inescapable for fabrication of USJs.…”