The role of defect excesses in damage formation in Si during ion implantation at elevated temperature

Damage accumulation in neon-implanted silicon with fluences ranging from 5 ϫ 10 14 to 5 ϫ 10 16 Ne cm −2 has been studied in detail. As-implanted and annealed samples were investigated by Rutherford backscattering spectrometry under channeling conditions and by transmission electron microscopy in order to quantify and characterize the lattice damage. Wavelength dispersive spectrometry was used to obtain the relative neon content stored in the matrix. Implantation at room temperature leads to the amorphization of the silicon while a high density of nanosized bubbles is observed all along the ion distribution, forming a uniform and continuous layer for implantation temperatures higher than 250°C. Clusters of interstitial defects are also present in the deeper part of the layer corresponding to the end of range of ions. After annealing, the samples implanted at temperatures below 250°C present a polycrystalline structure with blisters at the surface while in the other samples coarsening of bubbles occurs and nanocavities are formed together with extended defects identified as ͕311͖ defects. The results are discussed in comparison to the case of helium-implanted silicon and in the light of radiation-enhanced diffusion.

Section: Damage Accumulationmentioning

confidence: 99%

Damage accumulation in neon implanted silicon

Oliviero

Peripolli

Amaral

et al. 2006

“…However, above this temperature the crystalline-toamorphous transformation does not take place, irrespective of the dose. 1,2 High dose implantation at elevated temperatures has been used to synthesize a variety of compounds in silicon including silicon dioxide, silicon nitride and metal silicide buried layers. 3 Ion implantation at high temperatures provides the possibility of exploring damage-related phenomena at very high doses (Ͼ10 17 cm Ϫ2 ).…”

Section: Introductionmentioning

confidence: 99%

Damage accumulation in Si crystal during ion implantation at elevated temperatures: Evidence of chemical effects

Souza

Suprun-Belevich

Boudinov

et al. 2000

Damage in Si induced by irradiation with various light/medium mass ions at elevated temperatures and high doses (у3ϫ10 16 cm Ϫ2 ) was studied using Rutherford backscattering spectroscopy, cross-section transmission electron microscopy, and high resolution x-ray diffraction. The results obtained have shown that there is a marked variation in the damage accumulation for different ion species. For O ϩ and N ϩ ions a distinct layer with a low level of damage presenting negative strain is formed at the surface. It has been found that the magnitude of the strain does not correlate with the energy deposited in the collision cascades. In the cases of Ne ϩ and Mg ϩ implantation, a low damage accumulation occurs near the surface but no negative strain is formed. In contrast to the N ϩ and O ϩ cases, with the increase of the Ne ϩ or Mg ϩ dose (Ͼ1ϫ10 17 cm Ϫ2 ) the damage profile stretches almost to the crystal surface. It is proposed that in addition to the mechanism of spatial separation of Frenkel pairs taking place in the collision cascades, the ability of the implanted ions to form precipitates and complexes with Si atoms noticeably influences the damage formation during implantation at elevated temperatures.

“…In contrast to c-Si samples implanted with O ϩ , N ϩ , or Si ϩ at elevated temperatures, where a negatively strained layer is formed near the surface, 3,5,14 in the samples implanted with Ne ϩ only a positive strain is observed. In the case of Ne ϩ implantation, the ballistic mechanisms which produce an excess concentration of vacancies near the sample surface also take place.…”

Section: Discussionmentioning

confidence: 78%

“…2 It was previously demonstrated that implantation of c-Si with Si ϩ or O ϩ at elevated temperatures leads to formation of two distinct layers: a dislocation free near-surface layer, which presents mechanical strain of contraction, and a highly dislocated layer located around the region of the end of range of the ions. [3][4][5] This double layer structure appears to be formed due to a spatial separation of point defects formed from the Frenkel pairs in collision cascades. 6 The spatial separation of vacancies and self-interstitials results from the nonzero momentum component of the recoiled Si atoms in the beam incidence direction.…”

Section: Introductionmentioning

confidence: 99%

Strain development and damage accumulation during neon ion implantation into silicon at elevated temperatures

Cima

Boudinov

Souza

et al. 2000

The development of mechanical strain and accumulation of damage in silicon single crystals implanted with Ne ions to doses in the range of 0.1-1.0 ϫ10 17 cm Ϫ2 at temperatures from 200 to 600°C were investigated employing Rutherford backscattering spectrometry, high resolution x-ray diffraction ͑HRXRD͒ analysis and cross section transmission electron microscopy ͑XTEM͒. Two distinct layers have been found in the implanted material: A near-surface layer (Ͻ 0.2 m thick͒ where no extended defects are observed and a buried layer (Ϸ0.5 m thick͒ containing a dense array of dislocation loops and defect clusters. XTEM analysis revealed a distribution of small spherical cavities presumably filled with Ne, with a diameter Ͻ4 nm, extending along the entire depth of the implanted layer. HRXRD studies showed the presence of a positive strain ͑of expansion͒, irrespective of the implanted dose and temperature. The findings are discussed in terms of the proposed model which assumes that vacancy-type defects are consumed during the formation of Ne bubbles.