Impact of the end of range damage from low energy Ge preamorphizing implants on the thermal stability of shallow boron profiles
- SWAMP Center, Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States)
A fundamental understanding of the effect of scaling amorphous layers on the thermal stability of active concentrations is required for the formation of ultrashallow junctions. A study on the influence of boron on the evolution of the end of range defects for samples containing shallow amorphous layers formed by low energy germanium implants is conducted. Czochralski grown (100) silicon wafers are preamorphized with 1x10{sup 15} cm{sup -2}, 10 keV Ge{sup +} and subsequently implanted with 1x10{sup 15} cm{sup -2}, 1 keV B{sup +} such that high boron levels are attained in the end of range region. A sequence of anneals are performed at 750 deg. C, under nitrogen ambient for times ranging from 1 s to 6 h and the end of range defect evolution is imaged via plan-view transmission electron microscopy (TEM). Defect analyses are conducted utilizing quantitative TEM which indicates substantial differences in the defect evolution for samples with boron in the end of range. The extended defects observed are very unstable and undergo a fast dissolution. In contrast, stable defects are observed in the experimental control in which the evolution follows an Ostwald ripening behavior. Secondary ion mass spectroscopy analyses confirm the ephemeral nature of the defects observed and also demonstrates drastic reductions in interstitial supersaturation. In addition, uphill-type diffusion is observed to occur for a short time frame, which emphasizes a transient interstitial supersaturation. Correlation of this data with sheet resistance and active dose measurements conducted on a Hall measurement system strongly indicates the formation of boron interstitial clusters. The high boron concentrations and supersaturation levels attained at the anneal temperature enables the cluster formation. An estimate of the boron concentrations trapped in the clusters is determined from the active dose obtained from the Hall measurements and indicates concentrations much higher than those available in the end of range. This suggests an interstitial migration from the end of range to regions of higher boron levels. Since the end of range is in the vicinity of the highly doped layer it is not isolated from the strain effects induced by the high initial activation levels. Hence it is proposed that the tensile strain stimulates the interstitial migration from the end of range to the boron-doped layer. Consequently, the end of range defects dissolve as the interstitial supersaturation falls below levels required to sustain their evolution.
- OSTI ID:
- 20662142
- Journal Information:
- Journal of Applied Physics, Vol. 96, Issue 9; Other Information: DOI: 10.1063/1.1776624; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fluorine-enhanced boron diffusion in germanium-preamorphized silicon
Vacancy engineering by optimized laser irradiation in boron-implanted, preamorphized silicon substrate
Related Subjects
ANNEALING
BORON
CRYSTAL GROWTH
DOPED MATERIALS
EVOLUTION
GERMANIUM
GERMANIUM IONS
INTERSTITIALS
ION IMPLANTATION
ION MICROPROBE ANALYSIS
KEV RANGE 01-10
MASS SPECTROSCOPY
NITROGEN
SEMICONDUCTOR MATERIALS
SILICON
SUPERSATURATION
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 1000-4000 K
TIME DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY